IUSM Micro Core – Flashcards
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Unlock answersGram Positive envelope |
Peptidoglycan-B-linked NAG/NAM; protection/strength Teichoic Acids-glycerol Phosphate or ribitol phosphate polymer; promotes adhesion to epithelium Lipoteichoic acids-polyglycerol phosphate; holds together PM and PG; promotes adhesion plasma membrane |
Gram Negative Envelope |
Outer Membrane (lipopolysaccharide; OM proteins (porins/porin-like proteins)); Â peptidoglycan; Â periplasmic space; plasma membrane OM proteins involved in hydrolysis, antibiotic inactivation, adhesion, chemotaxis, transport Outer leaflet has LPS (endotoxin) PG in inter membrane space Gives bug negative overall charge for evasion of complement and phagocytosis |
Peptidoglycan Synthesis |
In cytosol, sequential addition of amino acids to UDP-NAM to form NAM-pentapeptide. (requires ATP) In inner leaflet, UMP is released leaving a di-P linkage; NAM pentapeptide is now attached to bactoprenol (membrane bound lipid like carrier); NAG is added to complex as well as amino acids; Complex crosses membrane; This disaccharide unit is attached to the end of the growing chain; transpeptidases crosslink adjacent glycan chains to form single NAM-NAG chain |
Gram Stain Procedure |
Stain purple with crystal violet/iodine Decolorization Counterstain with Safranin (red) |
Ribosomes |
70S (2 subunits of 50S and 30S) |
endospores |
All spores are Gram + rods Exosporium, spore coat, cortex, core Dipicolinic Acid is unique to spores and aids in resistance Sterilize in autoclave 120 > 20 minutes70% EtOH, 10% bleach, water |
mesosomes |
an organelle of bacteria that appears as an invagination of the plasma membrane and functions in DNA replication and cell division |
Proinflammatory effects of PG |
Fixes complement, drives PRR activation and TNF production |
Biofilm |
an organized community of microbial cells that has a capsule/slime layer over the entire population |
Capsule |
Hydrophillic network of polysaccharides Called slime layer if amorphous |
Functional types of pili |
Common or Somatic: attach to epithelial cells  Sex-only one per cell; involved in gene transfer  Composed of pilin which form a tube with a small hollow core |
Flagella |
Rotating helical structures anchored to PM for locomotion Monotrichous (at one pole) Lophotrichous->1 at a pole Amphitrichous-at both poles Peritrichous-all around the bacteria Has basal body in which central rod rotates; hook like joint, and flagellin filament |
Chemotaxis |
molecular mechanisms of directed movement |
General Secretory Pathway |
Sec proteins serve as chaperones ATP dependent Gram +/- |
Type 1 secretion |
Extends across both membranes Proteins exported w/o use of GSP ATP dependent No chaperones |
Type 2 secretion |
From periplasm into ECM ATP dependent Only provides second step for proteins already found in periplasm using sec proteins of GSP and Tat proteins |
Type V secretion |
Uses GSP or Tat Transports across outer membrane UNIQUE: ATP INDEPENDENT Similar to Type 2 |
Type III secretion |
Extends across both membranes has syringe like apparatus directly injects proteins across a 3rd membrane (toxins into host cells) Utilizes a chaperone and is ATP Dependent Notable use in Yersenia pestis (bubonic plague) |
Type IV Secretion |
Extends across both membranes ATP dependent Syringe like apparatus (like Type III) but can transport protein AND DNA (toxins and plasmids) |
Acid Fast Stain |
waxy material in outer wall of Mycobacterium (tb and leprae) and Nocardia species Stain with Carbol fuschin dye/destain with acid alcohol Acid fast wall is rich in mycolic acids which resist lysozyme and leads to fastidious slow growing bacteria |
Acid Fast Components |
Mycolic acids/polypeptides in outer layer consisting of free lipids, glycolipids and peptidoglycolipids Surface proteins are species specific Also, cord factor, trehalose mycolates and sulfolipids, arabinogalactan, lipoarainomannan, arabinomannan and Wax D |
LPS endotoxin |
Binds CD14 to drive toxic shock sydrome, a cytokine storm of IL I and TNF-alpha that induces fever and can lead to MTOF and death Comprised of Lipid A, core polysaccharide and O side chain; Lipd A contains glucosamine and is highly toxic; core polysacch is fairly conserved; O side chain is major surface antigen that shows most variability LPS assembly uses bactoprenol carrier |
Quarum sensing |
mechanism bacteria use to monitor own population and growth phase |
Highly Reactive Oxygen Species |
H2O2 and O2- Bacteria use catalase and superoxide dismutase to counteract these; bacteria that lack these enzymes are likely anaerobic |
Pathogenicity Islands |
organization of genes associated with pathogenesis; located in genomic DNA which is fundamentally different than rest of the genome |
Mechanisms of genetic diversity |
Mutation Recombination Transposition Genetic Exchange |
Antigenic Variation |
recombination used for this; mechanism for immune evasion and ability to change surface antigens; Â |
Homologous Recombination |
Donor and host DNA must have large regions of sequence that are similar or identical; recipient cell must make enzymes to replace segments of DNA such as RecA |
Site Specific Recombination |
Used by viruses to get into host genomre; limited DNA similarity; donor enzymes recognize unique DNA sequences |
Transposition |
genetic unit that can modulate its own relocation using Transposase and the 2 elements: insertion sequences and transposons; IS-use unzymes for site-specific recombination and have inverted repeats and direct repeats; only genes involved in transposition are encouded here Transposons: Have more enzymes that are involved in antibiotic resistance, toxins, etc. and transposition may be replicative |
Genetic Exchange |
Transfer of genetic material from donor to recipient cell; Uses Transformation, Transduction, or Conjugation |
Transformation |
Source of DNA is cell free. Uptake regulated by host cell and is called competence |
Conjugation |
Direct interaction between 2 bacteria with transfer of a plasmid (conjugative plasmid has genes to drive own transfer; non-conjugative lack these genes); Can occur between different species; varies between Gram +/- ; many plasmids carry virulence genes |
Gram + Conjugation |
Often transfer antimicrobial resistance, pili, adhesion, and toxin genes; can be pheromone dependent |
Gram - Conjugation |
F factor was first plasmid identified to modulate transfer of different chromosomal genes; Plasmid DNA is cut and a single strand passes thru Type IV secretion bridge; complimentary strands formed resulting in dsDNA plasmid in each cell; R plasmid encodes resistance genes, encode transposons that carry resistance |
Transduction |
transfer of genetic material is via a virus, a bacteriophage, and can be viral or viral/bacterial; Can be generalized or specialized; genes transferred can be toxins, virulence factors, enzymes, etc. Exogenote DNA is injected into host; Can be lytic (causes cell lysis) or lysogenic (passive replication without killing cell) |
Measurement of Anti-microbial Activity |
Diffusion tests (Kirby Bauer and E test) Macro dilution (test tubes) Microdilution (plates) Determine Min. Inhibitory comcentration or minimum bactericidal concentration |
B-lactams |
Block Cell Wall synthesis Penicillins, cephalosporins, monobactam, carbapenems Inhibit transpeptidation and activate autocatalytic enzymes (NOTE: Gram- bacteria make B-lactamases) |
B-lactamase inhibitors |
clavulanic acid, sulbactam, tazobactan |
Penicillins |
Natural Pen G & V Penicillinase -resistant: Oxacillin, nafcillin, cloxacillin, methicillin Amino Penicillins: ampicillin, amoxacillin Anti-pseudomonas: ticarcillin Extended spectrum: pepercillin |
1st Generation Cephalosporins |
cephalexin, cefazolin for non-life threatening infections/surgical prophylaxis |
2nd Generation Cephalosporins |
cefuroxime, cefoxitin Increased activity against Gram-, more resistant to B-lactamases |
3rd generation cephalosporins |
ceftriaxone, cefoperazone broad spectrum; CNS penetration |
4th generation cephalosporins |
cefepime broadest spectrum of activity against Gram +/- |
Monobactam |
Aztreonam Resistant to B-lactamases Effective against Gram- but NOT Gram + |
Carbapenems |
imipenem, meropenem, ertapenem resistant to most b-lactamases used for Gram+/- TOXIC |
Non-B-lactams |
Vancomycin, Bacitracin, others |
Vancomycin |
glycopeptide AB, blocks transglycosylation Kills Gram + (especially pen-resistant Staph) Some bacteria have Van-A for resistance |
Bacitracin |
Blocks dephosphorylation of bactoprenol Kills Gram + Administered topically |
Other non-B-lactams |
Cycloserine: D-alanine analog blocks cell wall synthesis Isoniazid: inhibits mycolic acid synthesis Ethambutol: inhibits arabinogalactan synthesis Ethionamide: inhibits mycolic acid synthesis |
Polymyxins |
Disrupt plasma membrane Bactericidal against Gram- |
Daptomycin |
Cubicin bactericidal lipopeptide depolarizes membrane Use against Gram + cocci |
Antimetabolite Antibiotics |
Sulfonamides (Sulfmethoxazole, dapsone): inhibits PAPA incorporation into dihydropteroic acid so inhibits folate synthesis; Bacteriostatic against Gram+/- but a lot of resistance so now used for UTI's from E.coli. Allergies common Trimethoprim (inhibits dihydrofolate reductase) Two are used synergistically against aerobes, Gram +/- cocci, bacilli |
Quinolones and Fluoroquinolones |
Inhibit DNA gyrase and DNA synthesis Ciprofloxacin, moxifloxicin, gatifloxicin Bactericidal against aerobes and fac. aerobes |
Rifamycins |
Inhibits DNA synthesis by inhibiting RNA polymerase rifampin, rifabutin, rifaximin Bactericidal for Gram +/some - Uses: mycobacterium tb, and prophylaxis for N. meningitis, and H. influenza type B |
Nitroimidazole |
metronidazole, tinidazole Damages DNA, not an inhibitor of synthesis Kills anaerobic bacteria, fungi, parasites Given with B-lactam to broaden spectrum |
Aminoglycoside AB |
streptomycin, gentamicin, amikacin Binds 30S, blocks initiation uses against aerobes TOXIC resistance slowly develops |
Tetracyclines |
tetracycline, doxycycline, tigercycline Binds 30S, stops elongation Bacteriostatic against some Gram + and Gram - rods and cocci, aerobes and anaerobes, cell wall deficient TOXIC to bones and teeth, GI Resistance via efflux; resistant to one, resistant to all |
Chloramphenicol |
Binds 50S, inhibits peptide bond formation Bacteriostatic against some Gram +/- TOXIC-aplastic anemia; bone marrow transplant needed |
Macrolides |
erythromycin, azithromycin, telithromycin Binds 50S, blocks translocation and/or inhibits peptide bond formation Bacteriostatic against some Gram +/- and some intracellular pathogens Resistance to one, resistance to all |
Lincosamides |
clindamycin Binds 50S, inhibits peptide bond formation Bacteriostatic against Gram+/- |
Mupirosin |
topical for gram + cocci inhibits synthesis of isoleucyl-tRNA |
Synercid |
Quinupristin+Dalfopristin FDA approved to treat vancomycin resistant E. faecium; also effective against vano-resistant staph; Binds 30S |
Linezolid |
an oxazolidinone Binds 50S site Treats VREF, MRSA, MSSA |
Miscellaneous Antimicrobials |
Methenamine and Nitrofurantoin (UTI's) Pyrazinamide (Mycobacterium) |
Antiseptic |
Used to reduce the number of microbes on skin surfaces ex) alcohols, iodophors, chlorhexidine, PCMX, triclosan |
Disinfectant |
high level disinfectants used for items involved with invasive procedures that can't withstand sterilization ex) glutaraldehyde, hydrogen peroxide, peracetic acid, chlorine Intermediate level cleans surfaces without spores ex) alcohols, iodophores Low level for blood pressure cuffs, etc ex) quaternary ammonium |
Disinfectant Survivors |
Alcohols: spores, some viruses and fungi halogens: some spores aldehydes: bacteriostatic at low conc phenols: spores, some viruses gases: cationic detergents: iodines: must clean off organic matter chlorhexidine: kills slowly hexachlorphene: only kills Gram + ; |
Major skin inhabitants |
S. epidermidis, Micrococcus sp., Corynebacterium sp., P. acnes |
minor skin inhabitants |
yeasts, S. aureus, Lactobacillus sp. |
Nose and nasopharynx inhabitants |
Major: S. epidermidis, Corynebacterium sp., ; Minor: S. aureus, Haemophilus sp., Streptococcus sp., Branhamella sp |
Mouth inhabitants |
Major: S. mitis, S. sanguis, S. salivarius, S. mutans (plaques and caries) ; Other: S. epidermidis, peptostreptococcus sp., Lactobacillus sp, Treponema sp. Actinomyces sp. Bacteroides sp., Fusobacterium sp., Veillonella sp |
Oropharynx Inhabitants |
Same as mouth plus Corynebacterium sp. |
Stomach inhabitants |
H. pylori |
Jejunum normal flora |
Corynebacterium sp., Lactobacillus sp., Enterococcus sp. |
Ileum Normal Flora |
Distal: Candida albicans, Enterobacteriaceae, Gram-anaerobes |
Large intestine Natural flora |
Strict anaerobes: Bacteroides sp., Fusobacterium sp., Eubacterium sp., Peptostreptococcus sp., Bifidobacterium sp., Minor: Enterococcus sp., Staphylococcus sp., Enterobacteriaceae, C. albicans |
Genitourinary Tract Normal flora |
Urethra sterile except distal part which has flora like skin Vagina, cervix: Lactobacillus sp., Bacteriodes sp., Corynebacterium sp., Sp. epidermidis, Enterococcus sp. ; In carriers: C. albicans, T. vaginalis |
Relapse |
When the underlying pathogen is activated and re-emerges to cause disease (ex. HSV) |
Recrudescence |
underlying pathogen persists but without causing apparent disease (HIV) |
Disease prevalance |
total number of cases in a population |
Incidence |
the number of new cases of a disease in a defined period of time |
Virulence Factors |
Pili/Fimbriae: adherence; resist phagocytosis Capsules/slime layers: resist phagocytosis; inhibit C3b deposition Exotoxins: AB (diptheria), non-AB(pore forming LLO), ; |
Actinomyces israellii |
Gram+, filamentous, fac/strict anaerobes inhabit mucosal surfaces Infection: pyogenic abscesses connected by sinus tracts; "sulfur granules" form in tissues; opp. infections; cervicofacial infections most common (assoc w poor oral hygiene or trauma) Control: penicillin, tetracycline, macrolide |
Nocardia asteroides |
Gram+, filamentous, partially acid fast, aerobic, fragment, common in soil Infections: survive/replicate in macrophages; cause exogenous bronchopulmonary infections in immunocompromised that disseminates to CNS; also cause primary cutaneous and lymphocutaneous infections and brain abscess Control: TMP-SMX, 3rd gen ceph. |
Peptostreptococcus/Streptococcus |
Gram+ cocci, anaerobes, non-spore forming, no cytochromes; predisposing conditions, proinflammatory cell walls Infections: brain abscess, pulmonary infection, intra-abdominal infection, female pelvic inf, skin and soft tissue infections Control: penicillin, clindamycin, imipenem |
Bacteroidese fragilis |
Gram-rods, anaerobes, non-spore forming, lack cytochromes 60% of intra-abdominal infections and 70% of anaerobic bacteremias enterotoxin Infections: brain, oral, URT, dental, sinuses, LRT, female genital tract inf., ; Control: drain, debride, metronidazole, clindamycin, chloramphenicol, imipenem |
Prevotella, Porphromonas, Fusobacterium |
Gram-rods, anaerobes, non-spore forming, lack cytochromes capsule, adhesins, enzymes=virulence factors ; Infections: brain, oral, URT, dental, sinuses, LRT, female genital tract inf., ; Control: drain, debride, metronidazole, clindamycin, chloramphenicol, imipenem |
Propionibacterium acnes |
Gram+ rods, anaerobes, non-spore forming, lack cytochromes Infections: associated with acne ; |
Bacillus |
gram+ rods, endospore-formers, common soil inhabitants, facultative anaerobes, catalase + |
B. anthracis |
Non-motile, Gram+rods, endospores, fac anaerobes, catalase + Virulence factors: zoonosis, polyglutamic acid capsule; toxins(PA-EF (calmodulin-dep adenylate cyclase to increase intracellular cAMP), PA-LF(protease that induces apoptosis/disrupts endothelial barrier Infections: Sx associated with toxin/route of entry; intestinal, inhalation, cutaneous all assoc w/ toxemia ; Control: Vaccine, penicillin, oxycycline, quinolone |
B. cereus |
Gram+rods, endospores, fac anaerobes, catalase+, motile Virulence factors: Heat labile (HL) and heat stable(HS) enterotoxins, cereolysin, lectithinase Infections: emetic (HS toxin) and diarrheal (HL toxin) diseases (food borne); other: bacteremia, pneumonia, ophthalmitis, osteomyelitis Control: proper food storage, supportive care, serious infections use Vancomycin or clindamycin |
B. subtilis |
Gram+rods, spores, fac anaerobes, catalase + ; emetic gastroenteritis, sepsis |
B. licheniformis |
Gram +rods, spores, fac anaerobes, catalase+ ; diarrheal gastroenteritis |
Bordetella pertussis and B. parapertussis |
Gram-coccobacilli, aerobe, capsule, pili Virulence factors: human reservoir, aerosol transmission, LPS, capsule, sol PG, pertussis toxin, invasive adenylate cyclase, adhesins (pertactin, filamentous hemagglutinin, pili, pertussis toxin, type 3 secretion Infections: pertussis in children, persistent cough in adults Control: vaccine, macrolide |
genus Borrelia |
Motile, microaerophilic, Gram-spirochete, no LPS, pro-inflammatory lipoprotein in OM, changes antigenic strux, zoonotic diseases, difficult to culture |
B. recurrentis |
Motile, microaerophilic, Gram-spirochete, no LPS, pro-inflammatory lipoprotein in OM, changes antigenic strux, zoonotic diseases, difficult to culture lice vector, humans only host Virulence: highly invasive, intracellular growth Infections: relapsing fever Control: avoid vectors, tetracyclines, macrolides |
B. hermsii |
Motile, microaerophilic, Gram-spirochete, no LPS, pro-inflammatory lipoprotein in OM, changes antigenic strux, zoonotic diseases, difficult to culture tick vector, rodents, small mammals are natural hosts Virulence: highly invasive, intracellular growth Infections: relapsing fever Control: avoid vectors, tetracyclines, macrolides |
B. burgdorferi |
Motile, microaerophilic, Gram-spirochete, no LPS, pro-inflammatory lipoprotein in OM, changes antigenic strux, zoonotic diseases, difficult to culture ; Virulence: highly invasive, tick vector, mice, deer, ; birds are resevoir; adhesins, Infections: Lyme disease (early localized-erythema chronicum migrans); (early disseminated-secondary skin lesions, facial nerve palsy, meningitis, carditis); late disease (arthritis) Control: avoid vectors; vaccine, doxycycline, amoxicillin, cefuroxime, cetriaxomne for serious infection |
Brucella melitensis (biovars or species melitensis, abortus, suis, canis) |
Gram-, non-motile coccobacilli, aerobe, catalase +, oxidase +, urease+ Virulence factors: animal resevoir,, transmit by direct contact or ingestion; LPS, fac. intracellular pathogen Infections: brucellosis, sepsis, granulomas or abscesses in reticuloendothelial tissue (LN, bone marrow, spleen, liver) Control: doxycycline+rifampin |
Campylobacter |
Gram-, curved bacilli, microaerophilic, motile at 37C, oxidase and catalase+ |
C. fetus and venerealis |
Gram-, curved bacilli, microaerophilic, motile at 37C, oxidase and catalase+ grows at 25C but not 42C Virulence factors: zoonotic with many animal reservoirs, transmit by direct contact, food, water; LPS, capsule (S protein that inhibits C3b binding) Infections: common in immune compromised , sepsis following gastroenteritis Control: avoid undercooked food/contaminated water, tetracyclines, macrolides, quinolones |
C. jejuni |
Gram-, curved bacilli, microaerophilic, motile at 37C, oxidase and catalase+ Grows at 42 NOT 25C Virulence factors: many animal reservoirs (esp food animals), transmit by contaminated food/water; LPS, invasive, enterotoxin?,, cytotoxin? Infections: leading cause of bacterial food-borne gastroenteritis (inflammatory), disseminated disease in immunocompromised; secondary complication with GBS and arthritis Control: avoid undercooked food or contaminated water tetracyclines, macrolides, quinolones |
genera Chlamydia and Chlamydophila |
strict intracellular bacteria, 2 form-life cycle: elementary bodies(infectious form) and reticulate bodies (replicative form); Gram- like envelope w/o PG |
Chlamydia trachomatis |
strict intracellular bacteria, 2 form-life cycle: elementary bodies(infectious form) and reticulate bodies (replicative form); Gram- like envelope w/o PG Virulence: intracellular pathogen, human reservoir, transmission route depends on dyndrome Infections: Trachoma (seros A, B, Ba, C; transmitted by direct contact or flies, keratitis); inclusion conjunctivitis (seros B,Ba,D-K; transmitted by direct contact), STD (seros B,Ba,D-K; urethritis, cervicitis; PID, epididymitis, prostatitis), lymphogranuloma venereum (seros L1-3, STD) Control: doxycycline or macrolides |
Chlamydophila psittaci |
strict intracellular bacteria, 2 form-life cycle: elementary bodies(infectious form) and reticulate bodies (replicative form); Gram- like envelope w/o PG Virulence: intracellular pathogen, bird reservoir, transmit by bite or inhalation Infections: atypical pneumonia Control: tetracyclines |
Chlamydophila pneumoniae |
strict intracellular bacteria, 2 form-life cycle: elementary bodies(infectious form) and reticulate bodies (replicative form); Gram- like envelope w/o PG Virulence: intracellular pathogen, human reservoir, transmit by aerosols Infections: (long incubation pd) pneumonia, bronchitis, sinusitis, pharyngitis, atherosclerosis Control: tetracyclines or macrolides |
Clostridium perfringens |
Gram+rods, strict anaerobes, spores, soil and GIT inhabitant histotoxic, aerotolerant and non-motile, 5 strains based on exotoxin profile (A-E); target hemolysis associated with alpha and theta toxins Virulence: exotoxins, alpha (most impt) and beta toxin (enteritis necroticans); enterotoxin Superantigen, heat labile; infection initiated by traumatic entry of endospores or inoculation of ischemic tissue or consumption of contaminated food (gastroenteritis) Infections: most assoc with A; sepsis, intra-abdominal, biliary tract, genital, pleuropulmonary, cellulits, fascitis, myonecrosis, gastroenteritis; (food poisoning from A), enteritis necroticans (C strain) Control: debridement + penicillin, clindamycin or metronidazole |
Other histotoxic Clostridia |
C. septicum (myonecrosis, neutropenic colitis) C. novyi, Csordellii, C. histolyticum (myonecrosis) C. difficile |
Clostridium difficile |
Gram+rods, strict anaerobes, spores, soil inhabitant; Virulence: human reservoir, survival of spores in hospitals, adhesins, enterotoxin (toxin A); cytotoxin (toxin B) Infections: self limiting diarrhea, pseudomembranous enterocolitis (antibiotic assoc/non-assoc) Control: Vancomycin or metronidazole |
Clostridium tetani |
Gram+rods, strict anaerobes, spores, soil inhabitant very oxygen sensitive, motile Virulence: traumatic entry of endospores, tetanolysin (hemolysin), tetanospasmin (neurotoxin) Infections: tetanus (spastic paralysis); generalized, localized, cephalic, neonatal Control: vaccine, would management, TIG, Td, penicillin or metronidazole |
Clostridium botulinum |
Gram+rods, strict anaerobes, spores, soil inhabitant motile, very resistant endospores Virulence: strain classification: group 1 (proteolytic, neurotoxins A,B, or F), group II (non-proteolytic, toxins B,E, or F) Infections: food, wound, infant botulism Control: anti-toxin (A,B,E), penicillin or metronidazole |
Corynebacterium diphtheriae |
Gram+pleomorphic bacillus, aerobe, black colonies on tellurite agar Virulence: human reservoir, transmit by respiratory droplets; diphtheria toxin (ADP-ribosylates EF2 and inhibits protein synthesis) Infections: signs and symptoms related to toxin (myocarditis, neuritis); cutaneous and pharyngeal Control: vaccine (DPT, Tdap); anti-toxin (only from CDC) + penicillin, macrolide, or tetracycline |
family Enterobacteriaceae |
enteric bacteria; ;25 genera; Gram- bacilli; oxidase -, facultative anaerobes; common inhabitants of GIT; serological typing based on O-polysacch antigens of LPS, K (capsular) antigens, and H (flagellar) antigens |
E. Coli |
enterobacter; lactose fermented Virulence: animal and human reservoir; transmit by contaminated food/water, direct contact, fecal-oral; adhesins, type III secretion, quorum sensing, cytotoxins, LPS, enterotoxins, capsule/biofilm Infections: GIT/non-GIT Control: avoid contaminated food/water/animals; symptomatic, TMP-SMX, quinolone, azithromycin or rifaxmin (no antibiotics for EHEC) |
E. Coli non-GIT infections and control |
UTI (adhesins, cytotoxin, LPS; TMP-SMX, floroquinolone, azithromycin Pneumonia (LPS; 3rd gen ceph.+aminoglycoside) Sepsis (LPS; 3rd gen ceph+aminoglycoside) Meningitis (neonatal; LPS, K1 strains; 3rd gen ceph+aminoglycoside) |
E.coli GIT infections |
EPEC (bundle-forming pili, type 3 secretion, intimin-mediated attachment; loss of microvilli in sm intestine/ absorption inhibited; infant diarrhea) ETEC (adhere to sm intestine via pili, secret HL toxin +/or HS enterotoxins; fluid and electrolyte loss; traveler's diarrhea) EIEC (attaches and invades lg intestine; absorption inhibited; inflammatory diarrhea that is watery to bloody; adult infection) EHEC (adheres to lg intestine epithelial cells via pili; spreads cell to cell via actin tails; secrete Shiga-like toxins I & II; absorption inhibited; watery diarrhea; O157:H7 & SLT-II causes hemolytic uremic syndrome) EAggEC/EAEC (adheres in stacked-brick pattern known as the aggregative adherence, non-inflam diarrhea) |
Klebsiella pneumoniae |
Enterobacter; non-motile; capsule Virulence: animal reservoir; transmit by aerosol; LPS, capsule Infections: lobar pneumonia; UTI, sepsis, meningitis Control: 3rd gen ceph+aminoglycoside Other species: K. Oxytoca, pneumoniae spp ozaenae, pneumoniae spp rhinoscleromatis |
Proteus mirabilis and P. vulgaris |
Enterobacter; swarming motility; urease pos, H2S produced Virulence: animal reservoir; transmit by direct contact; LPS, motility, urease Infections: UTI, stones (in compromised: pneumonia and sepsis) Control: 3rd gen ceph + aminoglycoside for life-threatening infections; quinolone, ampicillin, or amoxicillin for UTI |
Shigella sonnei other species: S. dysenteriae, flexneri, boydii) |
enterobacter; non-motile, no lactose fermentation, no H2S produced Virulence: human reservoir; transmit by direct contact, perrson-to-person, food or water; adherence, LPS, type III secretion, intracellular growth; Shiga toxin actin tails mediate cell to cell spread Infections: inflammatory diarrhea that is watery or classic dysentery Control: avoid contaminated food/water; quinolone, TMP-SMX, or rifaximin |
Salmonella enterica (serotypes choleraesuis, paratyphi, enteritidis, typhimurium, newport, heidelberg) |
enterobacter; motile, no lactose ferm; produces H2S; Virulence: human (typhi and paratyphi) and numerous animal reservoirs; transmit by direct contact, person to person, food or water; adherence, LPS, type III secretion; intracellular growth, actin rearrangement Infections: typhoid fever, inflammatory diarrhea that is watery and mucoid; sepsis Control: vaccine for typoid fever; avoid contaminated food/water; quinolone or TMP-SMX for GIT, ceftriaxone or chloramphemicol for sepsi |
Other Enterobacteriaceae |
Enterobacter, Serratia, Citrobacter Infections: nosocomial UTI & sepsis in immunocompromised Increased AB resistance from R-plasmid spread within whole family |
Francisella tularensis |
Gram-, pleomorphic coccobacillus, aerobe, catalase +, oxidase-, requires cysteine for growth, capsule Virulence: many animal reservoirs (esp rabbits); transmit via ticks, biting flies, direct, ingestion, or inhalation; LPS, capsule, fac. intracellular pathogen; very infectious Infections: (zoonosis) ulceroglandular, glandular, oculoglandular, pharyngeal, typhoidal, pneumonic Control: avoid infected animals; doxycycline, quinolone or gentamicin |
Haemophilus influenzae |
Gram- coccobacilli, fac anaerobe, catalase + requires hematin (X factor) & NAD or NADP (V factor) for growth, capsule (a-f) Virulence: human reservoir, aerosol transmission; LOS, capsule, OM proteins (adherence, invasion, intracellular growth), sol PG, IgA peptidase Infections: pharyngitis, sinusitis, pneumonia, bronchitis, otitis media, conjunctivitis, epiglottis, sepsis, meningitis (rare w/ vaccine) Control: vaccine; cefuroxime, ceftriaxone, amox for non-life threatening; rifampin prophylaxis |
Other Haemophilus |
non-typable/unencapsulated H. influenzae (assoc with otitis media, pneumonia, sinusitis, neonatal & post partum sepsis; treat with macrolide, TMP-SMX, quinolone) H. aphrophilus (assoc w endocarditis; treat w macrolide or quinolone) H. ducreyi (STD; chancroid, treat w macrolide) |
Helicobacter pylori |
Gram- spiral rod, microaerophilic, motile at 37C, urease, oxidase and catalase+ Virulence: human reservoir; transmit via fecal/oral or direct contact; LPS, urease, acid inhibitory protein, motility, mucinase, cytotoxin, adhesins (hemagglutin, sialic acid-binding protein, Lewis blood group adhesin) Infections: chronic gastritis leading to peptic ulcers; predisposes to carcinoma Control: macrolide or tetracycline+metronidazole+ bismuth subsalicylate+proton pump inhibitor |
Legionella pneumophila |
Characteristics: gram neg rod, aerobe, catalase pos, oxidase neg, hydrolyzes hippurate, motile, fastidious (requires high cysteine and iron levels), facultative psychro-thermophile Virulence factors: aquatic environment the natural reservoir (parasitizes amoebas and ciliated protozoans); transmission by aerosols (point-source); LPS (OM blebs), type II & IV secretion, intracellular growth (internalized by coiling phagocytosis), pili, Th1 response needed Infections: Pontiac fever (high attack rate, self limiting febrile disease), Legionnaires’ disease (low attack rate, predisposing condition, bronchopneumonia with dry cough that becomes productive; GIT, CNS, and kidneys may be involved) Control: macrolide, quinolone, or doxycycline |
Leptospira interrogans |
Characteristics: gram-negative tightly coiled spirochete, hook shaped at one or both ends; motile, aerobe Virulence factors: many animals are reservoirs; usually transmitted to humans by direct contact with contaminated water; LPS, invasive, intracellular growth Infections: anicteric leptospirosis (mild syndrome to systemic disease involving aseptic meningitis); icteric leptospirosis (Weil’s disease) with liver and kidney failure and vascular collapse Control: macrolide, doxycycline, or ceftriaxone |
Listeria monocytogenes |
Characteristics: gram + bacillus, fac anaerobe, catalase pos, oxidase neg, fac psychrophile, hydrolyzes esculin, motile at room temp Virulence factors: zoonotic, widespread in nature, many foods contaminated; transmitted by ingestion, transplacental (in utero), vaginal; facultative intracellular pathogen (Th1 needed to recover), lysteriolysin, internalin, actin tails, Act A Infections: pregnancy (sepsis, infection of fetus), neonatal (early and late onset diseases), adults (meningitis and sepsis most important; also gastroenteritis) Control: avoid processed meats; sulfameth-trimeth prophylaxis; treat with beta-lactam or betalactam+ aminoglycoside |
Pasteurella multocida |
Pasteurella multocida Characteristics: gram neg coccobacilli, facultative anaerobe, catalase pos, oxidase pos, encapsulated Virulence factors: found in the mouth of domestic animals (cats); transmission by bite; LPS, capsule Infections: cellulitis, sepsis Control: penicillin, tetracycline, or amoxicillin/clavulanic acid |
Moraxella catarrhalis |
Characteristics: gram neg diplococcus, aerobe, oxidase pos, catalase pos, grows on most media (not fastidious) Virulence factors: human reservoir (5-50% colonization); aerosol transmission; LOS (no somatic Opolysacch), adhesins (pili and OM proteins), Infections: important cause of otitis media, sinusitis, bronchitis, pneumonia Control: cefaclor, marcrolides, quinolones, trimeth-sulfameth |
Bartonella henselae |
Characteristics: gram neg rod Infections: cat scratch disease; bacillary angiomatosis in immunocompromised Control: rifampin, quinolone, or azithromycin |
genus Mycobacterium |
(gram-positive cytology with high glycolipid [mycolic acids, arabinogalactan, lipoarabinomannan] content in cell wall responsible for acid-fast staining, proinflammatory activities, and resistance to detergents and disinfectants; most slow growing and form serpentine cords; aerobic) |
M. tuberculosis |
Characteristics: produces niacin Virulence factors: human reservoir; aerosol transmission (prolonged contact needed); facultative intracellular pathogen (Th1 needed to control infection but also responsible for tissue damage); wall gycolipids promote resistance to intracellular killing, inhibit interferon-activation of macrophages, grows in the cytoplasm, and stimulate cell-mediated inflammatory injury Infections: Primary TB (first exposure), Secondary TB (reactivation), Progressive primary and secondary TB, and Miliary TB (disseminated disease involving the bone marrow, nodes, CNS, etc); infection converts to PPD+ Control: vaccine (limited use in USA); rifampin, isoniazid, pyrazinamide, ethambutol first-line drugs NOTE: M. bovis causes similar disease. It doesn’t produce niacin and many animals serve as reservoirs; transmission by ingestion.
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M. leprae |
Characteristics: intracellular bacterium (no growth on lab media) Virulence factors: human and armadillo reservoirs; transmission by nasal secretions; intracellular pathogen (Th1 needed but also mediates tissue damage), proinflammatory wall, phenolic glycolipid capsule, phenolase Infections: Hansen’s disease (leprosy): chronic disease of skin, peripheral nerves, & URT; tuberculoid (paucibacillary), borderline, lepromatous (multibacillary); infection converts to lepromin+ Control: dapsone + rifampin |
Other mycobacteria |
M. kansasii, M. marinum, M. scrofulaceum, M. ulcerans, M. fortuitum, M. avium, intracellulare many reservoirs (soil, water, etc); localized to disseminated infections ( cause disseminated disease in AIDS) treatment depends on species |
genera Mycoplasma and Ureaplasma |
(no cell wall results in pleomorphic morphology; have sterols in plasma membrane and require exogenous sterols for growth; smallest free-living procaryotes; all extracellular pathogens; membrane induces inflammation) |
M. genitalium |
Characteristics: prefers anaerobic growth Virulence factors: human reservoir; transmission by direct contact Infections: urethritis (prominent cause of NGU in men and women), cervicitis, and PID Control: doxycycline or quinolone |
M. pneumoniae |
Characteristics: aerobic Virulence factors: human reservoir; transmission by aerosols; adheres to cilitated epithelial cells (kills them with cytotoxic membrane and H 2O2), induces cytokines (IL-1, 6 & TNF) and inflammatory infiltrate Infections: pneumonia, tracheobronchitis, pharyngitis, otitis, Stevens-Johnson syndrome Control: doxycycline or azithromycin |
genus Neisseria |
(gram-negative, oxidase-positive diplococci; fastidious, requires extra CO 2; poor survival on environmental surfaces; human reservoir; high turnover of envelope components (LOS and PG) during growth)
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Neisseria meningitidis |
Virulence factors: aerosol transmission; LOS (blebs, no somatic O-polysacch), capsule (12 serogroups with B, C, and Y most common; A associated with epidemics), adhesins (OM proteins & pili), sol PG, IgA peptidase Infections: sepsis, meningitis, Waterhouse-Friderichsen syndrome Control: Vaccine; penicillin, chloramphenicol, or ceftriaxone |
N. gonorrhoeae |
Virulence factors: sexual transmission (neonatal infection in utero or during birth); LOS (blebs, no somatic O-polysacch), adhesins (OM proteins [Por mediates complement resistance and intracellular survival, Opa associated with attachment] pili [pili antiphagocytic]), sol PG, beta-lactamase, IgA peptidase Infections: urethritis in men, urethritis and cervicitis in women (~30% symptomatic); PID, disseminated gonococcal infection (arthritis w/ or w/o skin lesions), gonococcal opthalmia Control: ceftriaxone or cefixime + doxycycline or azithromycin if Chlamydia infection suspected |
Pseudomonas aeruginosa |
Characteristics: gram negative rod, aerobic (anaerobic with nitrate), motile, oxidase & catalase pos, nonfermenter, wide temp range, nutritionally versatile, fluorescein pigment (pyocyanin) produced by most Virulence factors: many environmental reservoirs (including hospitals); transmission by direct contact, food, water; LPS, pili, capsule or biofilm, proteases, cytotoxin, heat stable and labile hemolysins, exotoxin A, exoenzyme (exotoxin) S, Type III secretion, quorum sensing, antibiotic resistance Infections: mostly opportunistic and nosocomial; endocarditis, respiratory tract infections, pneumonia in cystic fibrosis, sepsis (ecthyma gangrenosum), meningitis, otitis, keratitis, bone and joint infections, UTI, skin (burn infections, generalized folliculitis) Control: aminoglycoside + anti-Pseudomonas beta-lactam |
Acinetobacter sp. |
Infections: (colonizes many moist environments) nosocomial pneumonia, sepsis, and soft tissue infections Control: a carbapenem or ampicillin-sulbactam (resistance is an issue)
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Burkholderia cepacia |
Infections: RT infections in cystic fibrosis, catheter-associated UTI & sepsis Control: trimeth-sulfmeth |
Stenotrophomonas maltophilia |
Infections: nosocomial sepsis, meningitis, UTI, wound infections Control: trimeth-sulfmeth
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Rickettsia rickettsii |
Characteristics: gram neg coccobacilli, strict intracellular pathogen, grows in cytoplasm of host cells, utilizes host ATP, NAD, and intermediates Virulence factors: animal reservoir; transmission by hard ticks (wood or dog; tick progeny infected); strict intracellular pathogen, weak endotoxin, phospholipase A destroys host membranes, actin tails mediate cell to cell spread Infections: RMSF (vasculitis, rash) Control: avoid tick contact; doxycycline or chloramphenicol |
Rickettsia prowazekii |
louse borne or epidemic typhus; human louse transmission/ rash |
Ehrlichia chaffeensis |
Characteristics: gram negative cytology, no peptidoglycan or LPS, intracellular pathogen (grows in phagosome=morula), life cycle involves reticulate and elementary - like bodies Virulence factors: animal reservoir; transmission by tick; strict intracellular pathogen of monocytes; immune response (gamma-interferon and activation of macrophages) associated with pathology Infections: human monocytic ehrlichiosis Control: avoid tick contact; doxycycline |
Anaplasma phagocytophilum |
Characteristics: similar to Ehrlichia Virulence factors: animal reservoir; transmission by tick; strict intracellular pathogen of myeloid precursors (neutrophils); pathogenesis related to immune response Infections: human granulocytic anaplasmosis (formerly human granulocytic ehrlichiosis) Control: avoid tick contact; doxycycline |
Coxiella burnetii |
Characteristics: gram negative pleomorphic bacillus that produces resistant endospore-like structures; obligate intracellular pathogen Virulence factors: animal reservoir; transmission by tick to animals, to humans by inhalation or ingestion; strict intracellular pathogen of reticuloendothelial cells; antigenic variation of LPS during infection Infections: Q-fever (acute febrile disease, atypical pneumonia most common; chronic with subacute endocarditis, hepatitis, CNS, and/or pulmonary involvement) Control: doxycycline
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genus Staphylococcus |
(gram-positive cocci that grow in clusters; facultative anaerobes, catalase positive, salt-tolerant) |
Staph aureus |
Characteristics: coagulase positive, ferments mannitol Virulence factors: human reservoir (carriers); transmission by direct contact; capsule and biofilm, quorum sensing; alpha, beta, delta, gamma-toxins; leukocidin (panton-Valentine); enterotoxins (super antigens), pyrogenic exotoxins (TSST-1), exfoliatins (super antigens), facultative intracellular parasite, proinflammatory cell wall components (induces IL1, TNF alpha), beta-lactamases, cell wall-bound adhesion molecules (fibrinogen, collagen, & fibronectin-binding proteins), Protein A, extracellular hydrolases Infections: folliculitis, furuncle, carbuncle, cellulitis, impetigo, scalded skin syndrome, sepsis, endocarditis, pneumonia, osteomyelitis, septic arthritis, purulent meningitis, food poisoning, toxic shock Control: hand washing; mupirocin, clindamycin for MRSA, beta-lactam (e.g. oxacillin, nafcillin) w/ or w/o aminoglycoside, or vancomycin; |
Staph. epidermidis |
Characteristics: coagulase negative Virulence factors: human reservoir, commensal and pathogenic strains; transmission by direct contact; biofilm, quorum sensing, proinflammatory cell wall components (induces IL1, TNF alpha), alpha and delta toxins, beta-lactamases Infections: neonatal bacteremia, nosocomial bacteremia, prosthetic devise infection, surgical infections, infections associated with peritoneal dialysis, urinary tract infection Control: hand washing; beta-lactams, vancomycin+rifampin or gentamicin |
Staph. saprophyticus |
Characteristics: resistant to novobiocin, coagulase negative Virulence factors: human reservoir; transmission by direct contact; specific adherence to urinary tract epithelial cells; proinflammatory cell wall components Infections: community-acquired UTI (mostly women) Control: trimeth-sulfmeth, quinolone, amox+clavulanic acid |
genus Streptococcus and Enterococcus |
(gram-positive cocci occurring in pairs and/or chains; facultative anaerobes; ferment lactic acid; catalase negative; alpha, beta, or gamma-hemolysis) |
Streptococcus pyogenes |
Characteristics: grows in chains, Group A carbohydrate, beta-hemolytic, sensitive to bacitracin Virulence factors: human reservoir; transmission by aerosols, food, water and direct contact; M-proteins, fimbriae, proinflammatory cell wall components, hyaluronic acid capsule, Streptolysin O & S, Streptococcal pyrogenic exotoxins (super antigens), intracellular invasion, adhesins (LTA, Protein F, fibrinogen binding protein, collagen binding protein, plasmin binding protein), C5a peptidase Infections: pharyngitis, scarlet fever, streptococcal toxic shock syndrome, impetigo, cellulitis, erysipela, necrotizing fasciitis, puerperal sepsis, rheumatic fever (antigenic mimicry), postinfectious glomerulonephritis Control: penicillin, macrolide, penicillin+clindamycin for invasive disease |
S. agalactiae |
Characteristics: grows in chains, Group B carb, weakly beta-hemolytic or gamma hemolytic, hydrolyzes hippurate, posituve CAMP test Virulence factors: human reservoir; transmitted by direct contact, person to person, transplacental; proinflammatory wall components, capsule, intracellular invasion, C5a peptidase Infections: neonatal infections (early and late onset); adult infections (sepsis, meningitis, respiratory and urinary tracts) Control: hand washing, hospital control policies; penicillin, vancomycin, penicillin or ampicillin+aminoglycoside
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Viridans strep: |
S. mutans, mitis, sanguis Characteristics: alpha or gamma hemolytic; most lack group antigen Virulence factors: proinflammatory wall components, adhesins Infections: inhabit oral cavity & tooth surfaces; most infections endogenous; associated with dental caries ( S. mutans) and endocarditis |
S. bovis group |
Characteristics: Group D carb Virulence factors: animal reservoir or endogenous source (GIT); transmitted by contaminated food or water; proinflammatory wall components Infections: endocarditis, bacteremia (assoc. with GI malignancy) Control: penicillin |
S. pneumoniae |
Characteristics: grows in pairs, optochin sensitive, large capsule Virulence factors: human reservoir; transmitted by aerosols or endogenous; capsule, proinflammatory wall components, adhesins (capsule, choline-binding protein, neuraminidase), pneumococcal surface protein A & C, autolysin, pneomolysin O, hyaluronate lyase, antibiotic resistance Infections: pneumonia, otitis media, meningitis, sinusitis Control: Vaccines (adult & child); CAP: macrolide, quinolone (e.g. gemifloxacin, moxafloxacin), ceftriaxone, cefotaxime; OM, sinusitis: amox+clav; Invasive disease: vanco+ceftriaxone or cefotaxime |
Enterococcus faecalis and faecium |
Characteristics: grows in chains, Group D carbohydrate, hydrolyze esculin, tolerates high salt and bile concentrations Virulence factors: endogenous (GIT & vagina) or nosocomial source; transmitted by direct contact or person to person; proinflammatory wall components, adhesins, cytolysin (bacteriocin), antibiotic resistance Infections: catheter-associated UTI, sepsis, endocarditis Control: hand washing, vancomycin, vanco + aminoglyside, quinupristin/dalfopristin, linezolid, |
Treponema pallidum (ssp pallidum) |
Characteristics: thin gram negative spirochete (special microscopy needed to observe), microaerophilic, motile, no growth on lab media, cardiolipin in OM Virulence factors: human reservoir; sexual transmission; highly invasive, intracellular growth, hyaluronidase, OM proteins associated with adherence, fibronectin coats outer membrane (antiphagocytic); tissue damage associated with immune/inflammatory response Infections: Syphilis (primary, secondary, latent, tertiary, congenital) Control: penicillin or doxycycline |
genus Vibrio |
(curved gram-negative bacilli, inhabit marine environments, motile by single polar flagellum, facultative anaerobes, oxidase positive) |
Vibrio cholerae |
Characteristics: killed by stomach acid; only seotypes O1 and O139 are associated with cholera Virulence factors: transmission by food or water; pili, cholera toxin (increases intracellular cAMP) Infections: noninflammatory watery diarrhea (potentially life threatening) Control: avoid contaminated food/water; tetracycline or erythromycin; rehydration |
V. parahaemolyticus |
Characteristics: halophilic Virulence factors: transmission by food or water; LPS, pili, cytotoxin/hemolysin (has enterotoxin activity) Infections: noninflammatory watery diarrhea to inflammatory dysentery-like gastroenteritis Control: avoid raw or undercooked seafood; doxycycline or ciprofloxacin |
V. vulnifcus |
Characteristics: halophilic Virulence factors: transmission by food or water; LPS, pili, proteases, cytotoxin, antiphagocytic capsule (resistance to complement) Infections: wound infections (rapidly progressive cellulitis), invasive gastroenteritis, sepsis Control: avoid raw or undercooked seafood; doxycycline or ciprofloxacin |
genus Yersinia |
(zoonotic, gram negative coccobacilli, facultative anaerobes; common virulence factors: LPS, facultative intracellular parasite, type III secretion, yadA gene products (adhesins and antiphagocytic proteins), yop/lcr gene products (OM proteins, toxic secreted proteins), V and W antigens (intracellular growth)) |
Yersinia pestis |
Characteristics: bipolar staining, capsule (fraction 1 antigen) Virulence factors: animal reservoir; transmission by flea bite or aerosols; antiphagocytic capsule (fraction 1 Ag) Infections: bubonic, pneumonic, septicemic plague Control: vaccine; gentamycin or doxycycline |