gram + bacteria Flashcards
Rheumatic Fever
(JONES) - the O is shaped like a heart
Joints; polyarthritis, MIGRATORY Heart - Carditis (mitral or aortic valve stenosis**) Nodules (subcutaneous) Erythema marginatium Syenham's Chorea
*get RF from cross-reacting antibodies against Group A Strep. This is a sequelae of UNTREATED Group A strep Pharyngitis
John Travolta was in Rheumatic Fever and he was Dancing all night (chorea mvmts) so his joints are aching (polyarthritis) and his heart was damaged from the stress of dancing so long (also he has nodules and a rash)
Group A Strep Pyogenes
a vampire named M-ASOn was quite sensitive (to bacitractin) and cried blood often (from his kidneys-PSGN)
- Group A, Beta-hemolytic
- Pyogenic: pharyngitis/strep throat, cellulits, Impetigo
- Toxigenic: Scarlet fever, “TSS”, Necrotiizing fasculitis
- Immunologic: Rheumatic fever, post-strep Glomerulonephritis (sore throat/impetigo)
Bacitracin sens.
ASO ab’s against Steptolysin O
ab’s against M protein may overcome phagocyte inhibition (but can –> RF)
Scarlet fever
Scarlet rash - blanche-able (cheeks get flushed, starts out splotchy –>sunburn w goos bumps “sandpaper like”), Strawberry (scarlet) tongue, Scarlet Throat or gray-white tonsillar exudates
Can predispose to Rheumatic Fever or Glomerulonephritis
Group B Strep aggalactiae
babies can make CAMP but are resistant to bacitracin. How Hippocritical (hippurate+ of them)
Bacitracin resistant (vs. A)
Beta hemolytic
Babies affected - meningitis, pneumonia, spesis
(Produce CAMP factor enlarges area of hemolysis formed by S. aureus)
-Hippurate test positive (can hydrolyze hippurate)
-no virulence without capsule* (antibodies form against capsule and cause quellengs)
-assoc w “RUSTY SPUTUM”, sepsis in sickle cell and asplenics
Viridians streptococi
Alpha-hemolytic
- found in the mouth/oropharynx
- Strep mutans –> dental caries (HULK had weird teeth and was a mutant, and was green!!)
- Strep Sanguis –> subacute bacterial endocarditis at DAMAGED valves (sanguis = blood)
- resistant to Optochin
- Most common cause of subacute bacterial endocarditis following dental work*
- produces extracellular polysaccharides (Dextrans) using sucrose as substrate. Dextrans facilitate adherence to FIBRIN –> fibrin and pltlts deposited at sites of endothelial trauma/previously damaged valves.
the HULK was RESISTANT to OPTOmus-CHIN
Strep Pneumo
-LANCET shaped, Gram + cocci
-alpha hemolytic, Optochin sensitive
most common cause of MOPS: Meningitis, Otitis media (children), Pneumonia**, Sinusitis
-IgA protase+ (is capsulated)/+quelleng
MOPS: Most OPtochin Sensitive
-Bile soluble (but can’t grow in it)
- # 1 cause of pneumonia: adults >40 yr
- # 1 cause of meningitis: >6 yrs
Strep OVeRPaSs (green OVRP)
Viridans: Optochin Resistant
Pneumoniae: Sensitive
Staph aureus
Coagulase+ AND Catalase+
- Most common colonization site: the anterior nares (same for MRSA)
- Makes Protein A (a for aureus - binds Fc-IgG and prevents complement activation)
- -> skin infxns, organ abscesses, pneumonia, Acute bacterial endocarditis, Osteomyelitis (abscess formation in bone –> periosteal disruption, bone necrosis)
- TSST = superantigen –> Fever, vomiting, rash, desquamation, shock, end-organ failure
- Scalded skin, rapid-onset food poisoning (vomiting, abdml cramps > diarrhea)
- MRSA needs vanc
Novobicin:
NuRSES
Novobicin:
Staph saprophyticus: resistant; UTI in sexually active young women
Staph epidermidis: sensitive; catheter infxns, prosthetic joint infxns, prosthetic valve endocarditis.
Coag- staph: major cause of infxns in pts w indwelling catheters, implanted foreign bodies/prosthetics (e.g. valves) bc can produce a slime!
-Often methicillin resistant!! Treat w Vancomycin!
Clostridium difficile
Toxin A: Enterotoxin, binds to brush border of gut, chemoattractant for neutrophils, release cytokines –> mucosal inflammation, water diarrhea
Toxin B: cytotoxin, destroys the cytoskeletal structure of enterocytes –> Pseudomembranous colitis (fibrin deposition, epithelial cell necrosis)
Rx: Vancomycin, Metronidazole*
ANAEROBE
Bacillus Anthracis
the only bacterium w polypeptide capsule (D-GLUTAMATE)
- Cutaneous: black eschar –> bacteremia, death
- Pulmonary: Mediastinitis/widening, flu-like sxs, shock
- on microscopy: forms long chains that are “serepentine” “medusa head”
- Woolsorter’s ds: inhalation of spores from contaminated wool (think exposure to sheep,goat)
Bacillus cereus
Reheated rice syndrome!! Spores are heat-resistant
- Emetic type: Immediate. nausea and vomiting. Preformed toxin.
- Diarrheal type: Delayed (8-18 hrs). From spore itself. watery, nonbloody diarrhea. activates adenylate cyclase.
Listeria monocytogenes
Facultative intracellular microbe
- gram + rod
- from ingestion of unpasteurized milk/cheese and deli meats, or by vaginal transmission during birth
- Form “ACTIN rockets” by whcih they move from cell to cell
- “TUMBLING MOTILITY”
- ->Meningitis in immunocompormised and neonates
- -> mild gastroenteritis in healthy individuals
- -> amnionitis, septicemia, spontaneous abortions
- Can be cultured as low as 4 degrees celcsus (ice cream is cold!!)
- “Very narrow zone of Beta hemolysis”
Actinomyces israelli
gram +, anaerobe, branching/looks like fungi
- normal oral flora
- -> oral/facial abscesses (LUMPY JAW), yellow “sulfur” granules, PID in women w IUD
- RX: PCN
Nocardia
gram+ aerobe, branching/looks like fungus
ACID FAST
-found in soil (needs air in the soil!)
–> pumonary infxns in immunocompromised, cutaneous infxns after trauma in immunocompromised
RX: Sulfonamides
Mycobacteria TB
Primary: Mid-lobe, Ghon Complex (caseating granulomas/ghon focus + lymphadenopathy)
Secondary: Upper lobes
–> CNS (parenchymal tuberculoma, meningitis), Vertebral bodies (Potts), Lymphadenitis, Renal, GI
-Path: caseating granulomas, LANGHANS giant cells
-Virulent mycobacteria will grow as “serpentine” cords due to “Cord Factor”: establishes virulence (neutrophil inhibition, mito destruction, induced release of TNFalpha)
-Sulfatides (surface glycolipids) inhibit phagolysosomal fusion)
PPD+
Current infection
Past exposure
BCG vaccination
PPD-
No infection
Anergic (steroids, malnutrition, immunocompromised)
Sarcoidosis*
Mycobacterium leprae
- Armadillos! –>GRANULOMAS
- bacteria can invade SCHWANN CELLS
- Tuberculoid response: Th1 type, good. Dapsone, Rifampin
- Lepromatous response: mainly Th2 humoral (weak Th1 response), BAD. Dapsone, rifampin + clofazimine (diffuse skin thickening, hypopigmentation plaques w hair loss, Leonine facies, Paresis*, Regional anesthesia of motor and sensory nerves**, testicular destruction and blindness)
Group D Streptococci: Enterococcus faecalis / faecium
Gram + cocci, gamma-hemolytic/i.e. not.
- PCN resistant
- -> UTI, biliary tract infxn, subacute endocarditis.
- Grow in Bile and 6.5% NaCl
- VRE: Vancomycin-Resistant Enterococci are a cause of nosocomial infxns
Group D Streptococci: Non-eterococci
Strep bovis
- gram + cocci, gamma-hemolytic
- Colonize the gut –> Bacteremia and subacute endocarditis in colon ca. patients*
- valve doesn’t have to be damaged to get this infxn
- Grows in bile but NOT 6.5% NaCl (vs. Enterococci)
Staphylococcus epidermidis
Gram + cocci, catalase + (coag -)
- Infects foreign bodies: prosthetic devices, intravenous catheters <– produces adherent biofilms
- dominates nl skin flora and nose
- contaminates blood cultures
Clostridium botulinum
–> Food-borne, Wound, Infant (honey)
Corynebacterium Diptheriae
- Diptheria Toxin (ADP ribosylating AB-toxin.
- “B” binds to EGF receptors on cardiac and neural cells, induces endocytosis
- “A”/active-attaches ADP-ribosyl)
- MOA: inactive elongation factor (EF-2) and prevents protein synthesis
- -> Pharyngitis w pseudomembranes in throat, severe lymphadenopathy (bull neck) –> (severe, death) Cardiomyopathy*
- See bacteria w POLAR GRANULES that stain deeply w ANILINE DYE (like lollipops)
- Vaccine immunity: IgG against the B-binding unit of the Diptheria Exotoxin
- produces K Antigen, prevents phagocytosis so that it can invade the posterior pharynx (despite IgA)
Mycobacterium avium-intracellulare
- causes disseminated non-TB ds in AIDS; often resistant to many drugs
- Proplyax: azithromycin
- acid-fast (like all mycobacterium)
- “Cord factor” in virulent strains: inhibits macrophage maturation, induce release of TNF-alpha
- “Sulfatides” (surface glycolipids) inhibit phagolysosomal fusion
