Staph/Strep/Bacterial Meningitis – Flashcards
Unlock all answers in this set
Unlock answersquestion
| General staphylocci characteristics |
answer
|
question
| Protein A |
answer
Protein A is a major cell component of S. auerus; anti-phagocytic; latex agglutination assay is diagnostic.
Protein A binds nonspecifically to Fc region of particular isotypes of IgG. |
question
| How is teichoic acid used by S. aureus? |
answer
| Attachment to fibronectin-coated surfaces; inflammation |
question
| How is catalase used? Who is susceptible? |
answer
| differentiate staph from strep; Chronic granulomatous disease |
question
| How is coagulase used? |
answer
| differentiate staph aureus from other staph |
question
| TSST |
answer
| Staph exotoxin; superAg; induces TNF and IL-1; causes shock, fever, rash desquamation of skin, diarrhea (Food poisoning+diarrhea) |
question
| Staph Enterotoxins (SEs) |
answer
| resistant to boiling, emesis and diarrhea |
question
| Exfoliative toxins |
answer
| staph exotoxins; proteases breakdown bonds between keratinocytes -desmoglein-1 no longer maintains Keratin-Keratin attachment; SSSS, scarlet fever, bullous impetigo. |
question
| Labs to dx S. aureus |
answer
| Gram, beta-hemolytic on BAP with golden color (coag negative staph are white); Coagulase and Protein A used to identify in RLAT |
question
| Clinical manifestations of Staph infections |
answer
| Cutaneous - Boils (furuncles), carbuncles, folliculitis, styes, paronychia, bullous impetigo, SSSS; Burns/wounds- nearly all wounds are staph or P.aeruginosa, polymicrobic UTI - s. sapro ascends; Pneumonia 2ndary to viral RT- consider in CF patients due to immunocompromised Bact/Sept, osteomyelitis (MCCO), pyelonephritis, endocarditis, meningitis - usually spread from a skin infection; StahphTSS Food Poisoning -intoxication not infection, 2-6hr onset, violent vomiting |
question
| Tx of Staph |
answer
|
question
| Staph epidermidis - General characteristics |
answer
| Coag-negative;low virulence; MCCO prosthetic heart valve infection; Meth resistance = difficult to treat; MCCO nosocomial bacteremia. |
question
| Where do S. epidermidis infections occur |
answer
|
question
| S. saprophyticus profile |
answer
| Coag negative; normal flora, esp skin and periurethral community acquired UTI, distant 2nd to E. coli among outpatient UTI; S/S of uncomplicated cystitis - suprapubic pain, dysuria (burn), frequency/urgency, bacteuria (greater than 10^5, if < consider STI) |
question
| Streptococcus - general profile |
answer
| Gram + catatase negative; high maintenance growth requirements, but does well on BAP |
question
| Lancefield carbo antigen |
answer
| part of cell wall of strep; All pyogenics are typable, not all types are pyogenic; S. pyo is GAS; S. agalactiae is GBS; E.feacalis, E.faecium are GDS; S. pneumoniae = non-typable alpha-hemolytic (viridans is also non-typable alpha) |
question
| Strep capsules |
answer
| S. pneumonia - mulitple carbo types s.pyogenes - hyaluronic acid; GBS - several contain sialic acid (vaccines in trial) |
question
| Strep hemolysins |
answer
| Beta - complete, GAS, GBS, others Alpha -incomplete (greening), s. pneumonia, viridans Non- GDS are non-hemolytic |
question
| Source of strep infections |
answer
| Humans; endogenous and exogenous. |
question
| S. pyogenes (GAS) - virulence factors |
answer
| Fimbriae/fibrillae composed of M Protein + LTA; strep pyrogenic exotoxins (SPEs); hemolysins- SLO; hemolytic enzymes |
question
| S.pyo M protein and LTA |
answer
| Strep virulence factor; strongly antiphagocytic; anti-M abs protect against strep but multiple types exist; cross react with human heart tissue - possible contributor to ARhF; LTA is adhesin associated with M. |
question
| Streptcoccal pyrogenic exotoxins (SPE) |
answer
|
question
| S.pyo diagnostic for ARhF |
answer
| SLO - anti-SLO abs is diagnostic for ARF; |
question
| Lab dx of strep pyogenes (GAS) |
answer
| Beta-hemolytic, G+cocci in chains, Catalase negative, Bacitracin sensitive (B-BRAS) ; Definitive lab dx- lancefield (GAS) RADT |
question
| where is S.pyo reservoir? |
answer
| Pharnyx and Skin |
question
| Non-invasive GAS diseases |
answer
| Pharyngitis. ScarletFever. Skin infections -impetigo, erysipelas, cellulitis |
question
| Invasive GAS |
answer
| Septicemia, Toxic Strep Syndrome, necrotizing fasciitis and myositis |
question
| Non-suppurative diseases from strep |
answer
| ARhF, Acute Glomerulonephritis (AGN), E. nodosum |
question
| More about ARhF |
answer
| 2-3wks post strep throat, not skin; Dx is strengthened by proven strep throat, high anti-SLO titer; prompt abx (Pen V) for strep throat can prevent |
question
| More about AGN |
answer
| follow strep pharyngitis or strep skin infection, immune complex disease |
question
| S. agalactiae (GBS) characteristics |
answer
| Beta-hemolytic, bacitracin resistant (B-BRAS), antiphagocytic capsules contain sialic acid, colonize vagina during pregnancy |
question
| GBS virulence |
answer
| antiphagocytic capsules, if mother makes Ab neonate is protected; Chance of neonatal infection increases with prematurity and prolonged labor. Culture mom @ wk 35-37 and administer intrapartum Abx (Pen/Amp) |
question
| Lab Dx of GBS |
answer
| RADT for GBS |
question
| GBS Diseases |
answer
| Neonate sepsis, menigitis, respiratory disease; Soft tissue infections, septicemia, endocarditis in compromised adults (diabetics, AIDS, cardiodisease, immunocompromised) |
question
| Enterococcus - Class and characteristics |
answer
| GDS, bile-esculin +, NaCl tolerant, opportunistic endogenous source of infection, Pen/Ceph natural resistance, some strains are VRE. One of the most resistant bugs. |
question
| Opportunistic disease from Enteroccocus |
answer
| Nosocomial UTI or septicemia, Subacute endocarditis (SBE), esp valvular heart disease |
question
| Vancomycin Facts |
answer
| Inhibit peptidoglycan crosslink, Gram+ only, Resistance in staph is from Enterococcus but VRSA is rare; Tx entero infections, serious MRSA, pneumoccocal meningitis when PenR is prevalent (empiric prior to known sensitivity), C. difficile |
question
| How to treat VancR strains for Enterococcus |
answer
| IV Linezolid, Synercid, daptomycin |
question
| Viridans characteristics |
answer
| Nontypable, Alpha hemolytic strep, normal in pharyngeal/oral, opportunist, leading cause of SBE (look for damaged valves), Prophy Abx if damaged valves, murmurs for dental procedures; S. mutans has slimy sucrose capsule that attaches to teeth |
question
| S. pneumoniae characteristics |
answer
| Non-groupable alpha hemolytic; lancet shaped diplococci, Optochin-sensitive, bile soluble (OVPRS-distinguish Strep pneumo from viridans); |
question
| S. pneumoniae virulence |
answer
| Capsule (80 types) - anti-phagocytic, abs are protective, RATDs detect capsule Ag in sputum, CSF, blood, urine; Pneumolysin; surface protein; C-substance-binds CRP > synthesis of acute phase reactants |
question
| S. pneumoniae Lab dx |
answer
| Culture sputum, blood CSF (Ab sensitivity needed); gram stain of above, RADTs |
question
| S. Pneumonia Diseases - |
answer
|
question
| Risk factors of S. pneumoniae pneumonia |
answer
|
question
| Classic pneumoccal pneumonia |
answer
| Single rigor (shaking chill) rusty sputum, pleuritic pain, fever, lobar pneumonia/consolidation on CXR, lungs fill with fluid due to immune rxn |
question
| Treatment for pneumoccocal pneumonia |
answer
| AbxR is a consideration - order sensitivities for all isolates; Penicillin or ceftriaxone; If PenR use fluoroquinone (ie levofloxacin, fluoroquinone |
question
| Bugs that cause AOM |
answer
| S. pneumoniae, H. influenzae, M. catarrhalis |
question
| Meningitis symptoms |
answer
| headache, neck stiffness, fever, vomiting, photophobia, irritability, neuro dysfunction |
question
| CSF Fluid in meningitis |
answer
| usually associated with large #s of PMN, decreased glc, increased protein |
question
| Identification of bacterial agent causing meningitis |
answer
|
question
| Treatment of pneumococcal meningitis |
answer
| Pen/Ceph resisitance common in Memphis;Tx with Ceph+Vanc combo |
question
| Pneumococcal meningitis vaccine |
answer
| Pneumovax (multivalent, not conjugated, 23capsule types) - over 65, high risk, 5-7yrs resistance; Prevnar - safe and $$$$, abs seen in children @ 2 mos (young!), anamnestic response |
question
| Neisseria meningitidis - general |
answer
| Gram negative, kidney bean, oxidase positive, diplococci |
question
| Neisseria meningitidis - virulence |
answer
| Polysaccharide capsule is antiphagocytic and basis for polvalent vaccine; C6 deficiency is a risk |
question
| Neisseria meningitidis (meningococcal) diseases |
answer
|
question
| Meningococcal disease Tx |
answer
| Pen, ceftoxamine, ceftriaxone; only minor resistance problems |
question
| Meningococcal prophy |
answer
| Vaccine but not for Group B serotype, reccomended for all children @ 11-12yrs; Abx prophy (Cifprofloxacin or Rifampin) |
question
| H. influenzae - general |
answer
| disease/infection mirrors S. pneumo; Small non-motile G- rod; grows on CAP, not BAP |
question
| H. influenzae - disease |
answer
| Encapsultated (type b and f)- severe, systemic disease; HIB is invasive, polyribotol capsule is antiphagocytic; Unencapsulated strains - chronic resp disease in elderly, sinusitis, Otitis media, conjunctivitis in kids/infants. Peumonia also possible |
question
| H. influenzae -tx and prevention of disease |
answer
| 3rd gen CEPH with dex prior to abx; Conjugated type b vaccine is part of infant-childhood vaccination series |
question
| Listeria monocytogenes - general |
answer
| facultative intracellular parasite; infects mucosal epithelial cells and non immune macs/monos; Foodborne- meats/cheeses, uncommon but high mortality |
question
| Listeria monocytogenes - diseases |
answer
| Infections resemble flu, preggers 20x more likely; Bacteremia,meningitis in compromised and neonates |
question
| Tx of bacterial meningitis |
answer
|
question
| Panton-Valentine leukocidin |
answer
| Cytolytic toxin used by Staph aureus; found in most community acquired MRSA |
question
| Review of bacterial heart infections |
answer
| Aureus= ACUTE bacterial endocarditis; Virdans (S. mutans) & GDS (entero) = SBE. Virdans is leading cause of SBE ARhF is caused by S. Pyogenes and can lead to bacterial endocarditis by damaging valves. |
