Bacteria Gram Positive Flashcards
Identifying Staphylococci (catalase +)
Of Coagulase negative:
NOvobiocin -Saprophyticus is Resistant’ Epidermidis is sensitive : On the office “staph” retreat, there was NO StRESs.
Identifying Streptococci (catalse -)
Optochin-Viridians is Resistant; Pneumo is Sensitive: OVRPS
Bacitricin-Group B strep is Resistant; group A is Sensitive. B-BRAS
a-hemolytic bacteria
- Agar: green ring around colonies on blood agar
- Strep pneumo: (catalase - optochin sensitive)
- Viridians (catalase - optochin resistant
b-hemolytic bacteria
- Agar- clear area of hemolysis on blood agar
1) Staph aureus-catalse/coagulase+
2) Strep pyogenes-group A strep; ctatalse- bacitracin sensitive
3) Strep agalactiaegroup B strep; catalse - bacitracin resistant
4) Listeria monocytogenes-tumbling motility,meningitis of newborn, unpasteurized milk
Staph aureus
-Class: gram +, cocci in clusters; protein A; coag +
-Mode:?; bacteria or toxin
-Causes:
-Inflammatory disease- skin infections, organ abscess, pneumonia (often post flu), endocarditis, septic arthritis, osteo
-Toxin mediated disease- TSST-1-scalded skin, rapid onset food poisoning (enterotoxin)
-MRSA-serious nosocomial and CA infections. resistance to pen/nafcillin=altered penicillin binding protein
-Other: commonly nares (protein A)
-Know toxin mechanisms; difference from strep pyogenes TSS
Food poisoning - ingestion of preformed toxin within 2-6 hrs. HeAt stable.
Staph Epi
Class: cocci,clusters,catalase+, coag - ;
Medium: NOVOBIOCIN sensitive
Mode:?
Causes: Prosthetic devices, IV catheters bc of biofilms. –Normal skin flora; contaminates Bcx
Staph saprophyticus
Class: cocci, clusters,catalase+, coag -
Medium: NOVOBIOCIN RES
Causes: 2nd most common, uncomplex UTI in young F (1st is E. Coli)
Strep pneumo
Class: cocci, chains, catalase- ; a-hemolytic
“M.O.P.S are Most OPtochin sensitive”; Lancet shaped, Gram+, diplococci, Encapsulated, IgA protease (know function)
-Mode?
-Causes: Meningitis.Otitis media .Pneumonia. Sinusitis
Other:*Rusty sputum,sickle cell/ splenectomy sepsis, No virulence w/o capsule
Viridians group strep
Class: cocci, chains, catalase-; a-hemolytic, Medium: optochin res
Causes:
Oral flora->dental caries = Strep Mutans (“viridians live in mouth bc not afraid of ‘opto-CHIN”)
Subacute bacterial endocarditis-> damaged valve-Strep sanguinis (“sanguinis=blood=heart)
Strep pyogenes
Class: Group A; cocci, chains, catalase-; b-hemolytic; pyrrolidonyl arylamidase (PYR)+.
Medium: bacitracin sens
Mode:?
Causes:
Pyogenic-pharyngitis, cellulitis, impetigo, erysipelas
Toxigenic: scarlet fever, TS-like syndrome, nec fasc
Immuno- R fever, acute glomerulonephritis
Other:
ASO-means recent infection
M protein- virulence factor,enhances host defense +/- cause of R fever (know JONES)
Pharyngitis-> fever and g. nephritis (but mostly preceded by impetigo
Strep Agalactiae
Class: Group B, cocci, chains, catalase-; b-hemolytic;
Medium: bacitracin res.
Mode: Colonizes vagina–> babies–>
Causes: PNA,meningitis,sepsis
Other: CAMP factor= enlarges area of hemolysis by s. Aureus -Hippurate test +
Screen preggers at 35-37 wks, + gets Pen PPX
Enterococci
E faecalis and faecium Class: cocci, chains, catalase-; Group D strep; pen G res
Medium: hardier than other D, ok in 6.5% NaCL and Bile
Mode: normal gut flora
Causes: UTI, biliary infections, subacute endocarditis (s/p GI/GU procedures)
Other: vre ( vancomycin res) is important cause of nosocomials
scarlet fever
-Scarlet rash with sandpaper like texture, strawberry tongue, circumoral pallor, subsequent desquamation
Strep bovis
Class: cocci, chains, catalase-; Group D
Medium: Bile ok, not 6.5 NaCl
Causes: gallolyticus (bovis type I)-> bacteremia/subacute endocarditis
Other: associated with colon cancer*
Lancefield Grouping
-based on C carbohydrate on bacterial cell wall–puts enterocci and non-enterocci in group D
Gram + cocci
Strep (chains, catalase -)
Staph (clusters, catalase +)
Gram + rods
Clostridium ( anearobe)
Corynebacterium
Listeria
Bacillus (aerobe)
Branching
- Actinomyces (anaerobe, not AF)
- Nocardia (aerobe, AF+)
Corynebacterium diphtheriae
Class: Gram+ rods, club shaped; metachromic granules (blue+red)
Medium: black colonies on cystine-tellurite agar
Mode- tox by b-prophage– inhibits ADP ribosylation of EF2
Causes: pseudomembranous phrayngitis, +/- lymphadenopathy, myocarditis, and arrythmias
Other: toxoid vaccine
Lab -> Elek test for toxin
ABCDEFG: ADP-robosylation, B-prophage, Corynebacterium, Diphtheriae, EF2, Granules
Spores-bacterial
- End of stationary phase when nutrients limited
- res to heat/chemical; no metabolism
- **Dipicolinic acid at core
- Autoclave to 121 deg C for 15 min to kill
Bacteria that make spores
1) Bacillus anthracis-anthrax
2)Bacillus cereus- food poisoning
3) Clostridium botulinum-botulism
4) Clostridium diff- abc associated colitis
5) Clostridium perfringens-gas gangrene
6 Clostridium tetani-tetanus
7) Coxiella burnetti-q fever
Clostridia species
- Gram+, bacilli, spore-forming, obligate anaerobe
- tetani, botulinum, perfringens, difficile
C. tetani
Class: Gram+, bacilli, spore-forming, obligate anaerobe
Mode: dirty things piercing skin –>tetanospasmin that cleaves SNARE blocking inhibitory NT’s (GABA/Glycine) from Renshaw cells in S. cord.
Causes: spastic paralysis, trismus (lockjaw), risus sardonicus (raised eyebrow/open grin)
Other: vaccine prevents (know algorithm); rx with anti-tox +/- vaccine booster, diazepam
C. botulinum
Class: Gram+, bacilli, spore-forming, obligate anaerobe
Mode: preformed, heat labile tox-> botulinum-> blocks Ach release at NM junctions (adults pre-formed toxin, baby spores from honey
Causes- flaccid paralysis
other- anti-tox
C. perfringens
Class: Gram+, bacilli, spore-forming, obligate anaerobe
Mode: a-toxin–lecithinase a phospholipase –> Causes: myonecrosis ie gas gangrene and hemolysis
C. difficile
Class: Gram+, bacilli, spore-forming, obligate anaerobe
Mode: 2 toxins
Toxin A- enterotoxin- binds brush border
Toxin B-cytotoxin- cytoskeletal disruption via actin depol—>
Causes: pseudomembranous colitis & diarrhea
Other: diagnosed with toxins in stool and PCR
s/p abc like Clinda/amp
Anthrax
-Bacillus anthracis
Class: Gram+, bacilli, spore-forming
Mode-toxin (anthrax)
Other: polypeptide capsule (D-glutamate)
Cutaneous anthrax
painless paulues surrounded by vesicles–> ulcer with black eschar-painless,necrotic. sometimes –> bacteremia/death
Pulmonary anthrax
Spore inhalation
flu-like–> then fever, pulmonary hemorrhage, mediastinitis, and shock
Listeria monocytogenes
Class: Gram+, bacilli, facultative intracellular. tumbling motility
Mode:unpasteurized dairy/cold deli meats, transplacental, or vaginal–> “rocket tails via actin pol-> cell to cell spread without antibody
Causes: amnionitis, septicemia, spontaneous abortion, granulomatous infantisepticemia, neonatal (also immunocompromised/elderly) meningitis. Gastro in healthy people
Other: rx with ampicillin; gastro is self-limited
Actinomyces (branching)
Class: Gram+ anearobe
AF?: no
Where: normal oral
Causes: oral/facial abscess that drain through sinus tracts, yellow sulfur granules
Tx: Pen
SNAP-Sulfonamides=Nocardia; Actinomyces-Penicillin
Nocardia (branching)
Class: Gram+ aerobe
AF?: yes
Where: soil
Causes: pulmonary infection in i-compromised and cutaneous after trauma in i-competent
Tx:Sulfonamides
SNAP-Sulfonamides=Nocardia; Actinomyces-Penicillin
TB
Class: Acd fast +. pink rods
Medium:Lowenstein-Jensen
Mode: cord factor in virulent inhibits mac maturation and induces TNFa. Sulfatides (surface glycoproteins) inhibit phagolysosomal fusion
Causes: fever, night sweats, weight loss, cough (NP or ), hemoptysis
Other: INF g assay has fewer false positives with BCG. know PPD cut-offs
mycobacterium
- M tuberculosis- often resistant to drugs
- M avium-intracell, disseminated in AIDs, often resistant; azithro PPX with CD4 <50
- Scrofulaceum- cervical lymphadenitis in children
- M marinum- hand infxn in aquarium handlers
Leprosy
-M leopard
Class: AF+, rod, cool temps
Mode: infects skin, superficial nerves
Causes: (Hansen disease) gloves stocking loss of sensation
Lepromatous-diffuse skin, leonine (lion) facies, infectious, low cell mediates with humoral Th2
Tuberculoid- limited to hypoesthetic hairless kin plaques, TH1 type immune response
Other: armadillo is reservoir!
Tx: dapsone+ rifampin for tuberculoid; + clofazamine for lepromatous
Bacillus cereus
Class: Gram+, bacilli, spore-forming
Mode-spores survive in rice-> keeping warm causes germination +enterotoxin (cereulide)
Causes: emetic type, N/V in 1-5 hours; diarrheal -watery, no bloody and pain in 8-18 hrs.
Other: “reheated rice syndrome”
Primary TB
- Hilar nodes+ Ghon focus (lower/mid lobes)=Ghon complex
- CAN
1) Heal by fibrosis- PPD+
2) Progressive Lung (HIV/malnutrition)- death?
3) severe bacteremia->miliary-death
4) Pre-allerigc lympahtic or hematogenous spread-dormant in several organs-> reactivation later adult life
Secondary TB
2ndary: exposed, partially immune, hyper sensitized host–> reinfection with fibrocaseous cavitary lesion in upper lobes
-Can be from/or lead to extra pulmonary sources
CNS-parenchymal tuberculoma/meningitis
Vertebral bodies-Pott
Lymphadenitis, renal, GI, adrenals
