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Staph/Strep/Bacterial Meningitis
Covering bugs for Assessment 4
65
Microbiology
Professional
08/22/2010

Additional Microbiology Flashcards

 


 

Cards

Term
General staphylocci characteristics
Definition
  • Gram +
  • catalase +
  • clusters
  • mainly extracellular
Term
Protein A
Definition

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.

Term
How is teichoic acid used by S. aureus?
Definition
Attachment to fibronectin-coated surfaces; inflammation
Term
How is catalase used? Who is susceptible?
Definition
differentiate staph from strep; Chronic granulomatous disease
Term
How is coagulase used?
Definition
differentiate staph aureus from other staph
Term
TSST
Definition
Staph exotoxin; superAg; induces TNF and IL-1; causes shock, fever, rash desquamation of skin, diarrhea (Food poisoning+diarrhea)
Term
Staph Enterotoxins (SEs)
Definition
resistant to boiling, emesis and diarrhea
Term
Exfoliative toxins
Definition
staph exotoxins; proteases breakdown bonds between keratinocytes -desmoglein-1 no longer maintains Keratin-Keratin attachment; SSSS, scarlet fever, bullous impetigo.
Term
Labs to dx S. aureus
Definition
Gram, beta-hemolytic on BAP with golden color (coag negative staph are white);

Coagulase and Protein A used to identify in RLAT
Term
Clinical manifestations of Staph infections
Definition
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
Term
Tx of Staph
Definition
  • Meth/naf/ox if sensitive
  • MRSA=IV Vanc, linezolid, synercid, daptomycin
  • Penicillin is not effective
  • Sensitivity testing is important
Term
Staph epidermidis - General characteristics
Definition
Coag-negative;low virulence; MCCO prosthetic heart valve infection;

Meth resistance = difficult to treat;

MCCO nosocomial bacteremia.
Term
Where do S. epidermidis infections occur
Definition
  • foreign bodies (prostheses, IV cath, shunts - MCCO these infections d/t slime layer)
  • only slime layers infect prostheses
Term
S. saprophyticus profile
Definition
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)
Term
Streptococcus - general profile
Definition
Gram + catatase negative; high maintenance growth requirements, but does well on BAP
Term
Lancefield carbo antigen
Definition
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)
Term
Strep capsules
Definition
S. pneumonia - mulitple carbo types

s.pyogenes - hyaluronic acid;

GBS - several contain sialic acid (vaccines in trial)
Term
Strep hemolysins
Definition
Beta - complete, GAS, GBS, others

Alpha -incomplete (greening), s. pneumonia, viridans

Non- GDS are non-hemolytic
Term
Source of strep infections
Definition
Humans; endogenous and exogenous.
Term
S. pyogenes (GAS) - virulence factors
Definition
Fimbriae/fibrillae composed of M Protein + LTA; strep pyrogenic exotoxins (SPEs); hemolysins- SLO; hemolytic enzymes
Term
S.pyo M protein and LTA
Definition
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.
Term
Streptcoccal pyrogenic exotoxins (SPE)
Definition
  • Pyrogens/superAgs
  • Scarlet fever
  • STSS
  • Necrotizing fasciitis/myositis
  • SPEs are FERST
Term
S.pyo diagnostic for ARhF
Definition
SLO - anti-SLO abs is diagnostic for ARF;
Term
Lab dx of strep pyogenes (GAS)
Definition
Beta-hemolytic, G+cocci in chains, Catalase negative, Bacitracin sensitive (B-BRAS) ; Definitive lab dx- lancefield (GAS) RADT
Term
where is S.pyo reservoir?
Definition
Pharnyx and Skin
Term
Non-invasive GAS diseases
Definition
Pharyngitis. ScarletFever. Skin infections -impetigo, erysipelas, cellulitis
Term
Invasive GAS
Definition
Septicemia, Toxic Strep Syndrome, necrotizing fasciitis and myositis
Term
Non-suppurative diseases from strep
Definition
ARhF, Acute Glomerulonephritis (AGN), E. nodosum
Term
More about ARhF
Definition
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
Term
More about AGN
Definition
follow strep pharyngitis or strep skin infection, immune complex disease
Term
S. agalactiae (GBS) characteristics
Definition
Beta-hemolytic, bacitracin resistant (B-BRAS), antiphagocytic capsules contain sialic acid, colonize vagina during pregnancy
Term
GBS virulence
Definition
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)
Term
Lab Dx of GBS
Definition
RADT for GBS
Term
GBS Diseases
Definition
Neonate sepsis, menigitis, respiratory disease; Soft tissue infections, septicemia, endocarditis in compromised adults (diabetics, AIDS, cardiodisease, immunocompromised)
Term
Enterococcus - Class and characteristics
Definition
GDS, bile-esculin +, NaCl tolerant, opportunistic endogenous source of infection, Pen/Ceph natural resistance, some strains are VRE. One of the most resistant bugs.
Term
Opportunistic disease from Enteroccocus
Definition
Nosocomial UTI or septicemia, Subacute endocarditis (SBE), esp valvular heart disease
Term
Vancomycin Facts
Definition
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
Term
How to treat VancR strains for Enterococcus
Definition
IV Linezolid, Synercid, daptomycin
Term
Viridans characteristics
Definition
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
Term
S. pneumoniae characteristics
Definition
Non-groupable alpha hemolytic; lancet shaped diplococci, Optochin-sensitive, bile soluble (OVPRS-distinguish Strep pneumo from viridans);
Term
S. pneumoniae virulence
Definition
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
Term
S. pneumoniae Lab dx
Definition
Culture sputum, blood CSF (Ab sensitivity needed); gram stain of above, RADTs
Term
S. Pneumonia Diseases -
Definition
  • MOPS!!!
  • Meningitis (MCCO bacterial meningitis in adults/children)
  • Pneumonia,
  • URTI (Otitis media, sinusitis)
Term
Risk factors of S. pneumoniae pneumonia
Definition
  • Viral infections (flu, milder RTI),
  • Chronic pulmonary disease,
  • splenic disorders (sickle cell, diabetics),
  • EtOH abuse
Term
Classic pneumoccal pneumonia
Definition
Single rigor (shaking chill) rusty sputum, pleuritic pain, fever, lobar pneumonia/consolidation on CXR, lungs fill with fluid due to immune rxn
Term
Treatment for pneumoccocal pneumonia
Definition
AbxR is a consideration - order sensitivities for all isolates; Penicillin or ceftriaxone; If PenR use fluoroquinone (ie levofloxacin, fluoroquinone
Term
Bugs that cause AOM
Definition
S. pneumoniae, H. influenzae, M. catarrhalis
Term
Meningitis symptoms
Definition
headache, neck stiffness, fever, vomiting, photophobia, irritability, neuro dysfunction
Term
CSF Fluid in meningitis
Definition
usually associated with large #s of PMN, decreased glc, increased protein
Term
Identification of bacterial agent causing meningitis
Definition
  • Gram stain CSF,
  • Culture CSF and Blood (CAP/BAP)
  • sensitivities
Term
Treatment of pneumococcal meningitis
Definition
Pen/Ceph resisitance common in Memphis;Tx with Ceph+Vanc combo
Term
Pneumococcal meningitis vaccine
Definition
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
Term
Neisseria meningitidis - general
Definition
Gram negative, kidney bean, oxidase positive, diplococci
Term
Neisseria meningitidis - virulence
Definition
Polysaccharide capsule is antiphagocytic and basis for polvalent vaccine; C6 deficiency is a risk
Term
Neisseria meningitidis (meningococcal) diseases
Definition
  • Meningitis to bacteremia
  • Petechial to frankly purpuric skin rash in meningococcemia
  • meningococcemia is rare and deadly
Term
Meningococcal disease Tx
Definition
Pen, ceftoxamine, ceftriaxone; only minor resistance problems
Term
Meningococcal prophy
Definition
Vaccine but not for Group B serotype, reccomended for all children @ 11-12yrs; Abx prophy (Cifprofloxacin or Rifampin)
Term
H. influenzae - general
Definition
disease/infection mirrors S. pneumo; Small non-motile G- rod; grows on CAP, not BAP
Term
H. influenzae - disease
Definition
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
Term
H. influenzae -tx and prevention of disease
Definition
3rd gen CEPH with dex prior to abx; Conjugated type b vaccine is part of infant-childhood vaccination series
Term
Listeria monocytogenes - general
Definition
facultative intracellular parasite; infects mucosal epithelial cells and non immune macs/monos; Foodborne- meats/cheeses, uncommon but high mortality
Term
Listeria monocytogenes - diseases
Definition
Infections resemble flu, preggers 20x more likely; Bacteremia,meningitis in compromised and neonates
Term
Tx of bacterial meningitis
Definition
  • 3rd gen ceph, add ampicillin if listeria is suspected.
  • If resistant S. pneumo (MCCO) is possible add vanc.
Term
Panton-Valentine leukocidin
Definition
Cytolytic toxin used by Staph aureus; found in most  community acquired MRSA
Term
Review of bacterial heart infections
Definition
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.
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