USMLE Step 1 First Aid 2015 Microbiology – Flashcards
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Gram-positive Spherical (coccus)
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Staphylococcus Streptococcus
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Gram-positive Rod (bacillus)
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Bacillus Clostridium Corynebacterium Gardnerella (gram variable) Lactobacillus Listeria Mycobacterium (acid fast) Propionibacterium
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Gram-negative Sperical (coccus)
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Moraxella catarrhalis Neisseria
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Gram-negative Enteric Rod (bacillus)
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Bacteroides Campylobacter E. coli Enterobacter Helicobacter Klebsiella Proteus Pseudomonas Salmonella Serratia Shigella Vibrio Yersinia
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Gram-negative Respiratory Rod (bacillus)
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Bordetella Haemophilus (pleomorphic) Legionella (silver stain)
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Gram-negative Zoonotic Rod (bacillus)
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Bartonella Brucella Francisella Pasteurella
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Gram-positive Branching filamentous
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Actinomyces Nocardia (weakly acid fast)
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Gram-negative Pleomorphic
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Chlamydiae (Giemsa) Rickettsiae (Giemsa)
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Gram-negative Spiral (Spirochetes)
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Borrelia (Giemsa) Leptospira Treponema
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Gram-negative No cell wall
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Mycoplasma, Ureaplasma (contain sterols, which do not Gram stain)
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Gram stain limitations
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These Microbes May Lack Real Color. Treponema (too thin to be visualized). Dark-field microscopy or fluorescent antibody staining Mycobacteria (high lipid content; mycolic acids in cell wall detected by carbolfuchsin in acid- fast stain). Mycoplasma (no cell wall). Legionella pneumophila (primarily intracellular). Silver stain Rickettsia (intracellular parasite). Chlamydia (intracellular parasite; lacks classic peptidoglycan because of low muramic acid).
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Giemsa
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Certain Bugs Really Try my Patience. Chlamydia Borrelia Rickettsia Trypanosomes Plasmodium
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PAS (periodic acid-Schiff)
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PASs the sugar. Stains glycogen, mucopolysaccharides; used to diagnose Whipple disease (Tropheryma whipplei).
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Ziehl-Neelsen (carbol fuchsin)
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Acid-fast bacteria (Nocardia, Mycobacteria) Protozoa (Cryptosporidium oocysts) Alternative is auramine-rhodamine stain for screening (inexpensive, more sensitive but less specific).
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India ink
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Cryptococcus neoformans (mucicarmine can also be used to stain thick polysaccharide capsule red)
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Silver stain
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Fungi (e.g., Pneumocystis) Legionella Helicobacter pylori
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Media used for isolation, H. influenzae
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Chocolate agar
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Media used for isolation, N. gonorrhoeae, N. meningitidis
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Thayer-Martin agar
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Media used for isolation, B. pertussis
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Bordet-Gengou agar (Bordet for Bordetella) Regan-Lowe medium
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Media used for isolation, C. diphtheriae
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Tellurite agar, Löffler medium
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Media used for isolation, M. tuberculosis
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Löwenstein-Jensen agar
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Media used for isolation, M. pneumoniae
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Eaton agar
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Media used for isolation, Lactose-fermenting enterics
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MacConkey agar
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Media used for isolation, E. coli
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Eosin-methylene blue (EMB) agar
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Media used for isolation, Legionella
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Charcoal yeast extract agar buffered with cysteine and iron
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Media used for isolation, Fungi
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Sabouraud agar
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Media contents, Chocolate agar
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Factors V (NAD+) and X (hematin)
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Media contents, Thayer-Martin agar
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Vancomycin (inhibits gram-positive organisms), Trimethoprim, Colistin (inhibits gram-negative organisms except Neisseria), and Nystatin (inhibits fungi) Very Typically Cultures Neisseria
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Media contents, Bordet-Gengou agar Regan-Lowe medium
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Potato Charcoal, blood, and antibiotic
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Media contents, Eaton agar
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Requires cholesterol
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Media contents, MacConkey agar
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Fermentation produces acid, causing colonies to turn pink
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Media contents, Eosin-methylene blue (EMB) agar
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Colonies with green metallic sheen
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Aerobes, Examples
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Nagging Pests Must Breathe. Nocardia Pseudomonas aeruginosa and MycoBacterium tuberculosis Bacillus
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Anaerobes, Examples
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Anaerobes Frankly Can't Breathe Air. Fusobacterium Clostridium Bacteroides Actinomyces
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Anaerobes
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They lack catalase and/or superoxide dismutase and are thus susceptible to oxidative damage. Generally foul smelling (short-chain fatty acids), are difficult to culture, and produce gas in tissue (CO2 and H2). Anaerobes are normal flora in GI tract, typically pathogenic elsewhere. AminO2glycosides are ineffective against anaerobes because these antibiotics require O2 to enter into bacterial cell.
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Aerobes
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Use an O2-dependent system to generate ATP. Reactivation of M. tuberculosis (e.g., after immunocompromise or TNF-α inhibitor use) has a predilection for the apices of the lung, which have the highest Po2.
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Obligate intracellular, Examples
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Rickettsia, CHlamydia, COxiella. Rely on host ATP.
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Facultative intracellular, Examples
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Some Nasty Bugs May Live FacultativeLY. Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis.
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Encapsulated bacteria, Examples
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Streptococcus pneumoniae, Haemophilus influenzae type B, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumoniae, and group B Strep.
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Urease-positive organisms, Examples
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CHuck Norris hates PUNKSS. Cryptococcus, H. pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus.
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Catalase-positive organisms, Examples
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Cats Need PLACESS Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staphylococci, Serratia.
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Encapsulated bacteria vaccines, Examples
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Pneumococcal vaccine: PCV (pneumococcal conjugate vaccine, i.e., Prevnar); PPSV (pneumococcal polysaccharide vaccine with no conjugated protein, i.e., Pneumovax) H. influenzae type B (conjugate vaccine) Meningococcal vaccine (conjugate vaccine)
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Encapsulated bacteria
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Their capsules serve as an antiphagocytic virulence factor. Capsule + protein conjugate serves as an antigen in vaccines. Are opsonized, and then cleared by spleen. Asplenics have decr. opsonizing ability and thus incr. risk for severe infections. Give S. pneumoniae, H. influenzae, N. meningitidis vaccines.
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Encapsulated bacteria vaccines
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Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, enhancing immunogenicity by promoting T-cell activation and subsequent class switching. A polysaccharide antigen alone cannot be presented to T cells.
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Catalase-positive organisms
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Catalase degrades H2O2 into H2O and bubbles of O2 A before it can be converted to microbicidal products by the enzyme myeloperoxidase. People with chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with certain catalase ⊕ organisms.
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Pigment-producing bacteria
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Actinomyces israelii—yellow "sulfur" granules, which are composed of filaments of bacteria. S. aureus—yellow pigment. Pseudomonas aeruginosa—blue-green pigment. Serratia marcescens—red pigment.
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Bacterial virulence factors
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Protein A IgA protease M protein These promote evasion of host immune response.
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Protein A
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Binds Fc region of IgG. Prevents opsonization and phagocytosis. Expressed by S. aureus.
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IgA protease
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Enzyme that cleaves IgA. Secreted by S. pneumoniae, H. influenzae type B, and Neisseria (SHiN) in order to colonize respiratory mucosa.
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M protein
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Helps prevent phagocytosis. Expressed by group A streptococci. Shares similar epitopes to human cellular proteins (molecular mimicry); possibly underlies the autoimmune response seen in acute rheumatic fever.
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Type III secretion system
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Also known as "injectisome." Needle-like protein appendage facilitating direct delivery of toxins from certain gram-negative bacteria (e.g., Pseudomonas, Salmonella, Shigella, E. coli) to eukaryotic host cell.
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Peptidoglycan, Function
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Gives rigid support, protects against osmotic pressure.
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Peptidoglycan, Chemical composition
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Sugar backbone with peptide side chains cross-linked by transpeptidase.
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Cell wall, Function
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Major surface antigen.
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Cell wall, Chemical composition
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Peptidoglycan for support. Lipoteichoic acid induces TNF and IL-1.
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Outer membrane (gram negatives), Function
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Site of endotoxin (lipopolysaccharide [LPS]); major surface antigen.
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Outer membrane (gram negatives), Chemical composition
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Lipid A induces TNF and IL-1; O polysaccharide is the antigen.
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Plasma membrane, Function
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Site of oxidative and transport enzymes.
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Plasma membrane, Chemical composition
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Phospholipid bilayer.
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Ribosome, Function
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Protein synthesis.
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Ribosome, Chemical composition
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50S and 30S subunits.
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Periplasm, Function
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Space between the cytoplasmic membrane and outer membrane in gram-negative bacteria.
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Periplasm, Chemical composition
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Contains many hydrolytic enzymes, including β-lactamases.
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Pilus/fimbria, Function
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Mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation.
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Pilus/fimbria, Chemical composition
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Glycoprotein.
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Flagellum, Function
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Motility.
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Flagellum, Chemical composition
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Protein.
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Spore, Function
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Resistant to dehydration, heat, and chemicals.
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Spore, Chemical composition
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Keratin-like coat; dipicolinic acid; peptidoglycan.
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Plasmid, Function
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Contains a variety of genes for antibiotic resistance, enzymes, and toxins.
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Plasmid, Chemical composition
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DNA.
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Capsule, Function
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Protects against phagocytosis.
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Capsule, Chemical composition
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Organized, discrete polysaccharide layer (except Bacillus anthracis, which contains d-glutamate).
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Glycocalyx, Function
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Mediates adherence to surfaces, especially foreign surfaces (e.g., indwelling catheters).
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Glycocalyx, Chemical composition
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Loose network of polysaccharides.
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Endotoxin, Source
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Outer cell membrane of most gram-negative bacteria
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Endotoxin, Secreted from Cell
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No
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Endotoxin, Chemistry
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Lipopolysaccharide (structural part of bacteria; released when lysed)
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Endotoxin, Location of Genes
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Bacterial chromosome
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Endotoxin, Toxicity
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Low (fatal dose on the order of hundreds of micrograms)
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Endotoxin, Clinical effects
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Fever, shock (hypotension), DIC
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Endotoxin, Mode of Action
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Induces TNF, IL-1, and IL-6
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Endotoxin, Antigenicity
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Poorly antigenic
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Endotoxin, Vaccines
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No toxoids formed and no vaccine available
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Endotoxin, Heat-stability
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Stable at 100°C for 1 hr
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Endotoxin, Typical diseases
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Meningococcemia; sepsis by gram-negative rods
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Exotoxin, Source
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Certain species of gram-positive and gram-negative bacteria
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Exotoxin, Chemistry
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Polypeptide
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Exotoxin, Location of Genes
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Plasmid or bacteriophage
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Exotoxin, Toxicity
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High (fatal dose on the order of 1 μg)
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Exotoxin, Clinical effects
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Various effects
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Exotoxin, Mode of action
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Various effects
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Exotoxin, Antigenicity
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Induces high-titer antibodies called antitoxins
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Exotoxin, Vaccines
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Toxoids used as vaccines
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Exotoxin, Heat-stability
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Destroyed rapidly at 60°C (except staphylococcal enterotoxin)
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ExotoxinTypical diseases
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Tetanus, botulism, diphtheria
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Exotoxin, Secreted from Cell
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Yes
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Exotoxins that Inhibit protein synthesis
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Diphteria toxin Exotoxin A Shiga toxin (ST) Shiga-like toxin (SLT)
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Exotoxins that Increase fluid secretion
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Heat-labile toxin Heat-stable toxin Edema toxin Cholera toxin
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Exotoxins that Inhibit phagocytic ability
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Pertussis toxin
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Exotoxins that Inhibit release of neurotransmitter
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Tetanospasmin Botulinum toxin
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Exotoxins that Lyse cell membranes
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Alpha toxin Streptolysin O
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Superantigens causing shock
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TSST-1 Exotoxin A
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Endotoxin (especially lipid A) activates
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Macropages -> Il-1: Fever -> TNF-α: Fever, Hypotension -> Nitric oxide: Hypotension Complement -> C3a: Hypotension, Edema -> C5a: Neutrophil chemotaxis Tissue factor -> Coagulation cascade: DIC
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Genes for the following 5 bacterial toxins are encoded in a lysogenic phage
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ShigA-like toxin Botulinum toxin (certain strains) Cholera toxin Diphtheria toxin Erythrogenic toxin of Streptococcus pyogenes
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Gram ⊕ Catalase ⊕ Coagulase ⊕
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S. aureus
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α-hemolytic bacteria
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Form green ring around colonies on blood agar. Streptococcus pneumoniae Viridans streptococci
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Gram ⊕ Catalase ⊕ Coagulase (-) Novobiocin ⊕ Urease ⊕
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S. epidermidis
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Gram ⊕ Catalase ⊕ Coagulase (-) Novobiocin (-) Urease ⊕
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S. saprophyticus
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Gram ⊕ Catalase (-) Optochin sensitive, Encapsulated, IgA protease, Lancet-shaped, α-hemolytic
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S. pneumoniae
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Gram ⊕ Catalase (-) Optochin resistant, α-hemolytic
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Viridans group Strepptococci
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Gram ⊕ Catalase (-) Bacitracin sensitive, β-hemolytic, pyrrolidonyl arylamidase (PYR) ⊕, M Protein
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Group A - S. pyogenes
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Gram ⊕ Catalase (-) Bacitracin resistant, β-hemolytic
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Group B - S. agalactiae
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Gram ⊕ Catalase (-) Growth in bile, not 6.5% NaCl
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Nonenterococcus (S. bovis)
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Gram ⊕ Catalase (-) Growth in bile and 6.5% NaCl
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Enterococcus (S. faecalis)
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β-hemolytic bacteria
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Form clear area of hemolysis on blood agar. Staphylococcus aureus Streptococcus pyogenes—group A strep Streptococcus agalactiae—group B strep Listeria monocytogenes (tumbling motility, meningitis in newborns, unpasteurized milk)
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Gram ⊕ Catalase ⊕ Urease ⊕, Aerobe, Acid fast
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Nocardia
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Pneumococcus is associated with
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"rusty" sputum, sepsis in sickle cell disease and splenectomy.
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Pharyngitis can result in
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rheumatic "phever" and glomerulonephritis.
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Impetigo more commonly precedes
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glomerulonephritis than pharyngitis.
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Scarlet fever
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scarlet rash with sandpaper-like texture strawberry tongue circumoral pallor subsequent desquamation
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Streptococcus agalactiae (group B streptococci), Treatment in pregnancy
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Screen pregnant women at 35-37 weeks of gestation. Patients with ⊕ culture receive intrapartum penicillin prophylaxis.
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Lancefield grouping is based on
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differences in the C carbohydrate on the bacterial cell wall. Variable hemolysis.
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Corynebacterium diphtheriae, Diagnosis
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Gram-positive rods with metachromatic (blue and red) granules and ⊕ Elek test for toxin. Black colonies on cystine-tellurite agar.
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Spore-forming bacteria
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Bacillus anthracis: Anthrax Bacillus cereus: Food poisoning Clostridium botulinum: Botulism Clostridium difficile: Antibiotic-associated colitis Clostridium perfringens: Gas gangrene Clostridium tetani: Tetanus Coxiella burnetii: Q fever
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C. tetani, Prevention and Treatment
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Prevent with tetanus vaccine. Treat with antitoxin +/− vaccine booster, diazepam (for muscle spasms).
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C. botulinum, Treatment
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Treat with antitoxin.
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C. difficile, Treatment
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Metronidazole or oral vancomycin. For recurrent cases, consider repeating prior regimen, fidaxomicin, or fecal microbiota transplant.
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Listeria monocytogenes, Treatment
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Treatment: gastroenteritis is usually self limited; ampicillin in infants, immunocompromised, and the elderly as empirical treatment of meningitis.
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Actinomyces, Treatment
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Penicillin
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Nocardia, Treatment
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Sulfonamides
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M. avium-intracellulare , Prophylaxis
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Prophylaxis with azithromycin when CD4+ count < 50 cells/mm3.
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Leprosy (Hansen disease), Treatment
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Treatment: dapsone and rifampin for tuberculoid form; clofazimine is added for lepromatous form.
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Gram (-) Dipplococci, Glucose fermenter, Maltose fermenter
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N. meningitidis
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Gram (-) Dipplococci, Glucose fermenter, Maltose nonfermenter
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N. gonorrhoeae
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Gram (-) Catalase (+) Oxidase (+) Urease (+) comma shaped, creates alkaline environment
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Helicobacter pylori
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Gram (-) Oxidase (+) , comma or s-shaped, grows at 42°C
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Campylobacter jejuni
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Gram (-) Oxidase (+) , comma shaped, grows in alkaline media
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Vibrio cholerae
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Gram (-) Rods, Lactose nonfermenter, Catalase (+) Oxidase (+) Aerobe
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Pseudomonas
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Gram (-) Rods, Lactose nonfermenter, Oxidase (-) Facultative intracellular, Encapsulated,
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Salmonella
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Gram (-) Rods, Lactose nonfermenter, Oxidase (-) Urease (+)
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Proteus
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Gram (-) Rods, Lactose nonfermenter, Oxidase (-)
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Shigella Yersinia
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Gram (-) Rods, Lactose fermenter, Encapsulated
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E. coli
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Gram (-) Rods, Lactose fermenter, Encapsulated, Urease (+)
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Klebsiella
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Gram (-) Rods, Lactose fermenter, Catalase (+)
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Serratia
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Gram (-) Rods, slow Lactose fermenter
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Citrobacter Serratia
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Gram (-) Rods, fast Lactose fermenter
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E. coli Klebsiella Enterobacter
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Gram (-) "coccoid" rods, Encapsulated
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Haemophilus influenzae
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Gram (-) "coccoid" rods
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Pasteurella—animal bites Brucella—brucellosis Bordetella pertussis
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Gram negative stains
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pink
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Gram positive stains
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purple/blue
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Gonococci, Treatment
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ceftriaxone + (azithromycin or doxycycline) for possible chlamydial coinfection
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Meningococci, Treatment
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ceftriaxone or penicillin G
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Haemophilus influenzae, Treatment
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Treat mucosal infections with amoxicillin +/− clavulanate. Treat meningitis with ceftriaxone. Rifampin prophylaxis for close contacts.
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Legionella pneumophila, Treatment
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macrolide or quinolone
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Pseudomonas aeruginosa, Treatment
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Depending on source and severity, treatment may include: Extended-spectrum β-lactams (e.g., piperacillin, ticarcillin, cefepime) Carbapenems (e.g., imipenem, meropenem) Monobactams (e.g., aztreonam) Fluoroquinolones (e.g., ciprofloxacin) Aminoglycosides (e.g., gentamicin, tobramycin) For multidrug-resistant strains: colistin, polymyxin B
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Gonococci, Prevention
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Condoms decr. sexual transmission. Erythromycin ointment prevents neonatal transmission
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Meningococci, Prevention
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Rifampin, ciprofloxacin, or ceftriaxone prophylaxis in close contacts
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Fecal-oral transmission through person- to-person contact or via ingestion of poultry, meat, unpasteurized milk. Contact with infected animals (dogs, cats, pigs) is also a risk factor.
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Campylobacter jejuni
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Dark red "currant jelly" sputum (blood/mucus).
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Klebsiella
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Produces pyocyanin and has a grape-like odor.
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Pseudomonas
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Pseudomonas typical in
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Burn victims
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Ecthyma gangrenosum
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Rapidly progressive, necrotic cutaneous lesion B caused by Pseudomonas bacteremia. Typically seen in immunocompromised patients.
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E. coli virulence factors:
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Fimbriae: Cystitis, Pyelonephritis K capsule: pneumonia, neonatal meningitis LPS endotoxin: septic shock
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Common antecedent to Guillain-Barré syndrome and reactive arthritis.
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Campylobacter jejuni
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Hot tub folliculitis
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Pseudomonas
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Prompt oral rehydration is necessary.
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Vibrio cholera, Treatment
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Vibrio cholera, Treatment
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Prompt oral rehydration is necessary.
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Pet feces (e.g., puppies), contaminated milk, or pork.
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Yersinia enterocolitica
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Poultry, eggs, pets, and turtles (reptiles) are common sources
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Salmonella spp.
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Shigella in order of decreasing severity
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S. dysenteriae S. flexneri S. boydii S. sonnei
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Typhoid fever, Symptoms
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Rose spots on abdomen constipation abdominal pain fever
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Typhoid fever, Treatment
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ceftriaxone or fluoroquinolone
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H. pylori, Treatment
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triple therapy: proton pump inhibitor + clarithromycin + amoxicillin (or metronidazole if penicillin allergy).
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Lyme disease, Treatment
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doxycycline, ceftriaxone.
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broad-based ataxia, ⊕ Romberg, Charcot joint, stroke without hypertension.
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3° syphilis, signs
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Gummas (chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis, "general paresis"), Argyll Robertson pupil
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3° syphilis, Symptoms
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3° syphilis, Symptoms
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Gummas (chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis, "general paresis"), Argyll Robertson pupil
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VDRL test
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VDRL detects nonspecific antibody that reacts with beef cardiolipin. Inexpensive, widely available test for syphilis, quantitative, sensitive but not specific.
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VDRL false positives
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Viral infection (mono, hepatitis) Drugs Rheumatic fever Lupus and leprosy
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Jarisch-Herxheimer reaction
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Flu-like syndrome (fever, chills, headache, myalgia) after antibiotics are started; due to killed bacteria (usually spirochetes) releasing endotoxins.
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Zoonotic bacteria Anaplasma spp.
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Anaplasmosis Ixodes ticks (live on deer and mice)
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Zoonotic bacteria Bartonella spp.
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Cat scratch disease, bacillary angiomatosis Cat scratch
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Zoonotic bacteria Borrelia burgdorferi
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Lyme disease Ixodes ticks (live on deer and mice)
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Zoonotic bacteria Borrelia recurrentis
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Relapsing fever Louse (recurrent due to variable surface antigens)
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Zoonotic bacteria Brucella spp.
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Brucellosis/undulant fever Unpasteurized dairy
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Zoonotic bacteria Campylobacter
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Bloody diarrhea Puppies, livestock (fecal-oral, ingestion of undercooked meat), unpasteurized milk, poultry, cats, dogs, pigs
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Zoonotic bacteria Chlamydophila psittaci
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Psittacosis Parrots, other birds
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Zoonotic bacteria Coxiella burnetii
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Q fever Aerosols of cattle/sheep amniotic fluid
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Zoonotic bacteria Ehrlichia chaffeensis
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Ehrlichiosis Ambylomma (Lone Star tick)
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Zoonotic bacteria Leptospira spp.
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Leptospirosis Animal urine
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Zoonotic bacteria Francisella tularensis
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Tularemia Ticks, rabbits, deer fly
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Zoonotic bacteria Mycobacterium leprae
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Leprosy Humans with lepromatous leprosy; armadillo (rare)
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Zoonotic bacteria Pasteurella multocida
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Cellulitis, osteomyelitis Animal bite, cats, dogs
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Zoonotic bacteria Rickettsia prowazekii
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Epidemic typhus Louse
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Zoonotic bacteria Rickettsia rickettsii
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Rocky Mountain spotted fever Dermacentor (dog tick) Fleas
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Zoonotic bacteria Rickettsia typhi
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Endemic typhus Fleas
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Zoonotic bacteria Salmonella
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Diarrhea (which may be bloody), vomiting, fever, abdominal cramps Reptiles and poultry
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Zoonotic bacteria Yersinia pestis
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Plague Fleas (rats and prairie dogs are reservoirs)
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Clue cells
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Gardnerella vaginalis, Vaginosis
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Amine whiff test
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mixing discharge of vaginosis with 10% KOH enhances fishy odor.
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Vaginosis, Treatment
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metronidazole or clindamycin
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Palms and soles rash is seen in
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Coxsackievirus A infection (hand, foot, and mouth disease), Rocky Mountain spotted fever 2° Syphilis (you drive CARS using your palms and soles).
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disease occurs primarily in the South Atlantic states, especially North Carolina.
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Rocky Mountain spotted fever
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Rash typically starts at wrists and ankles and then spreads to trunk, palms, and soles.
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Rocky Mountain spotted fever
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Typhus, Rash
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Rash starts centrally and spreads out, sparing palms and soles.
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Ehrlichiosis
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Ehrlichia, vector is tick. Monocytes with morulae (berry-like inclusions) in cytoplasm.
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Anaplasmosis
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Anaplasma, vector is tick. Granulocytes with morulae in cytoplasm.
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Treatment for all: Rocky Mountain spotted fever Typhus Ehrlichiosis Anaplasmosis Q fever
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Doxycycline
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Chlamydiae, Treatment
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azithromycin (favored because one- time treatment) or doxycycline.
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Lymphogranuloma venereum, Treatment
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doxycycline
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Mycoplasma pneumoniae, Treatment
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macrolides, doxycycline, or fluoroquinolone (penicillin ineffective since Mycoplasma have no cell wall).
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X-ray looks worse than patient.
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Mycoplasma pneumoniae
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High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs.
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Mycoplasma pneumoniae
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More common in patients < 30 years old:
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Mycoplasma pneumoniae
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Frequent outbreaks in military recruits and prisons.
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Mycoplasma pneumoniae
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Cell wall lacks classic peptidoglycan (due to reduced muramic acid), rendering β-lactam antibiotics less effective.
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Chlamydiae
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Systemic mycoses
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fluconazole or itraconazole for local infection; amphotericin B for systemic infection
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Can mimic TB (granuloma formation):
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Systemic mycoses
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Mississippi and Ohio River valleys.
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Histoplasmosis
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Histoplasmosis, Topography
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Mississippi and Ohio River valleys.
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Bird or bat droppings.
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Histoplasmosis
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Histoplasmosis, Histology
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Macrophage filled with Histoplasma (smaller than RBC)
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States east of Mississippi River and Central America.
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Blastomycosis
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Blastomycosis, Topography
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States east of Mississippi River and Central America.
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Blastomycosis, Histology
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Broad-base budding (same size as RBC)
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Southwestern United States, California.
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Coccidioidomycosis
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Coccidioidomycosis, Topography
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Southwestern United States, California.
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Coccidioidomycosis, Histology
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Spherule (much larger than RBC) filled with endospores
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Case rate incr. after earthquake
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Coccidioidomycosis
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Latin America.
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Paracoccidioidomycosis, Topography
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Paracoccidioidomycosis, Topography
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Latin America.
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Paracoccidioidomycosis, Histology
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Budding yeast with "captain's wheel" formation (much larger than RBC)
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Tinea capitis, Associations
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lymphadenopathy alopecia scaling
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Tinea corporis, Can be aquired from
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contact with an infected cat or dog.
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Tinea pedis Three varieties:
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Interdigital - most common Moccasin distribution Vesicular type
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Tinea versicolor, Cause
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Malassezia spp. (Pityrosporum spp.), a yeast-like fungus (not a dermatophyte despite being called tinea).
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Tinea versicolor, Treatment
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topical and/or oral antifungal medications, selenium sulfide.
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Candida albicans, Treatment
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topical azole for vaginal; nystatin, fluconazole, or caspofungin for oral/ esophageal; fluconazole, caspofungin, or amphotericin B for systemic.
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Aspergillus fungiatus, Histology
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Septate hyphae that branch at 45° angle. Conidiophore with radiating chains of spores.
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Candida albicans, Histology
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Pseudohyphae and budding yeasts at 20°C. Germ tubes at 37°C.
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Septate hyphae that branch at 45° angle. Conidiophore with radiating chains of spores.
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Aspergillus fungiatus, Histology
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Pseudohyphae and budding yeasts at 20°C. Germ tubes at 37°C.
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Candida albicans, Histology
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Aflatoxin is produced by: Aflatoxin is associated with:
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Aspergillus species HCC
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Cryptococcus neoformans, Histology
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5-10 μm yeasts with wide capsular halos and unequal budding in india ink
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5-10 μm yeasts with wide capsular halos and unequal budding in india ink
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Cryptococcus neoformans, Histology
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Found in soil, pigeon droppings.
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Cryptococcus neoformans
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"Soap bubble" lesions in brain.
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Cryptococcus neoformans
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Disease mostly in ketoacidotic diabetic and/or neutropenic patients (e.g., leukemia)
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Mucormycosis
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Mucormycosis, Treatment
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surgical debridement, amphotericin B.
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Pneumocystis jirovecii, Treatment
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TMP-SMX, pentamidine, dapsone (prophylaxis only), atovaquone (prophylaxis only). Start prophylaxis when CD4+ count drops to < 200 cells/mm3 in HIV patients.
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Diffuse, bilateral ground-glass opacities on CXR/CT A . Diagnosed by lung biopsy or lavage. Disc-shaped yeast forms on methenamine silver stain of lung tissue
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Pneumocystis jirovecii
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Dimorphic, cigar-shaped budding yeast that lives on vegetation
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Pneumocystis jirovecii
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Sporothrix schenckii, Treatment
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itraconazole or potassium iodide.
