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Flashcards in Gram pos bacteria Deck (36):

staph is catalase pos, strep is catalase neg



S. epidermis full name, morphology, catalase status, coagulase status

staphylococcus epidermis, round clusters, catalase positive, coagulase negative


S. saprophyticus full name, morphology, catalase status, coagulase status

staphylococcus saprophyticus, round clusters, catalase positive, coagulase negative


S. aureus full name, morphology, catalase status, coagulase status, where it's normally found

staphylococcus aureus, round clusters, catalase positive, coagulase positive; Normal flora of nares, axilla and groin


S. aureus infection symptoms?

Abscesses - folliculitis, furuncles and carbuncles
Impetigo- “honey crusted” lesions, contagious
Endocarditis- destruction of heart valves
Necrotizing fasciitis, necrotizing pneumonia

Staphylococcal Scalded skin syndrome (SSSS)- caused by epidermolytic cytotoxins and exfoliative toxin (super-antigens)
Toxic shock syndrome- Enterotoxin B causes TSS (super-antigen)
Food poisoning- ingestion of preformed Staphylococcal enterotoxin (a super-antigen), heat labile, due to improperly cooked, stored or re-heated food


where are coagulase negative staph. usually found?

"sticky" opportunistic pathogens--> found on Prosthetic joints, Orthopaedic hardware, Indwelling catheters
UTIs in females--> saprophyticus


S. pyogenes full name, hemolysis state, Lancefield grouping

Streptococcus pyogenes, beta hemolysis, group A


S. agalactiae full name, hemolysis state, Lancefield grouping

streptococcus agalactiae, beta hemolysis, group B


S. dysgalactiae full name, hemolysis state, Lancefield grouping

streptococcus dysgalactiae, beta hemolysis, group C/G


S. pneumoniae full name, hemolysis state,

streptococcus pneumoniae, alpha hemolysis (viridans strep group)


what symptoms do group A strep usually cause?

strep throat, inflamed pharynx (say Aaaa)
--scarlet fever (soft tissue inflammation from endotoxin); cellulitis/erysipelas; streptococcal TSS (from super antigen); necrotizing fasciitis
Immune mediated
GAS antigens (M-protein) similar to that of heart tissue= Rheumatic fever
Valvular dysfunction (endocarditis?)
Immune complex deposition in kidneys=Post
streptococcal glomerulonephritis


what symptoms do group B strep usually cause?

Badness for babies, cause of neonatal meningitis/pneumonia/sepsis


what symptoms do group C/G strep cause?

also sore throat


S. anginosus full name, where does it reside, what does it cause, gram stain

Streptococci anginosus, resides in GI/urinary tract; causes abscesses; part of viridans group strep-->alpha hemolysis; gram positive


what bacteria make up VGS?

ABMMS-->angiosus, bovis, mutans, mitis, salivarius


S. bovis full name, symptoms, gram stain

Strep bovis- bacteremia in setting of colon cancer, gram pos--blue


S. mutans full name, symptoms, gram stain

Strep mutans- tooth decay, gram pos--blue


S mitis full name, symptoms, gram stain

Strep mitis (S. pneumo is a member)- pneumonia, sepsis, endocarditis, gram pos--blue


where is strep pneumoniae found, what is its morphology and hemolysis status, virulence factors, and the diseases it causes?

normally in the nasopharynx; encapsulated gram pos diplococci, alpha hemolysis;
virulence factors are a polysaccharide capsule (90+ types)--Antiphagocytic shield- “covers” antigens, impedes opsonisation; and autolysin--an enzyme which causes self-destruction so other virulence factors can be released

-otitis media


entercoccus gram stain, catalase status

gram pos, in chains, catalase negative


what are the aerobic spore forming GP bacilli?

Bacillus sp


what are the aerobic non-spore formingGP bacilli?

Corynebacterium sp


what are the anaerobic spore forming GP bacilli?

clostridium sp


what are the anaerobic non-spore forming GP bacilli?



skin and soft tissue infections by B. cereus and B. anthracis?

B. cereus- burn wound infx mediated by exotoxinshemolysins, proteases, phospholipases= TISSUE DESTRUCTIVE enzymes
B. anthracis- anthrax toxin
Depending on portal of entry…abrasion vs inhalation
Starts with black eschar and subsequent severe edema, shock…..death


corynebacterium example, and what does it cause?

C. diphtheria (“leather”)- nasal carriage
Only strains that have acquired the TOX gene encoding an exotoxin from a bacteriophage (a virus that infects bacteria) cause ”diptheria”
LOCAL effects-->Airway obstruction
“leathery” pseudomembrane- dead cells, fibrin, WBCs, RBCs and bacteria
Bull neck- swollen larynx and lymph nodes
DISTANT effects Myocardial damage and Nerve damage caused by exotoxin


what are the common routes of transmission for listeria?

Fecal-oral transmission- contaminates fruits, vegetables, unpasteurized milk/cheeses, meat products esp. DELI MEATS
Survives and replicates during refrigeration!


C. difficile mech of ac

Abx induced killing of normal gut flora SPORES survive C. diff flourishes Toxin A and B producing strains cause severe diarrhea pseudomembranes megacolon DEATH


describe the routes of exposure to C. botulinum and the effects

C. botulinum- neurotoxin caused inhibition of motor neuron function= PARALYSIS
Wound- direct inoculation with spores/bacteria that produces toxin
Foodborne (canned preserves)- ingestion of preformed toxin
Infant (honey)- ingestion of spores spores germinate and bacterium produces toxin“floppy baby”
Iatrogenic- overdose of the injection flat affect
Onset of symptoms depends on whether pre-formed toxin (hours) or spores (days-weeks) have been ingested


modes of transmission for c. tetani?

Portal of entry-“dirty”wounds (LACK OF A TETANUS SHOT)
Adults - Skin popping=sub-q drug abuse, gardening injuries, motor-vehicle accidents (“road rash”)
Neonatal- umbilical cord stump or circumcision


actinomyces morphology, symptoms and exposure

Actinomyces- long, thin, filamentous Gram positive rods
Normal GI (GUM to BUM) and vaginal flora
Indolent infections, but destructive.. commonly mistaken for “cancer”
Cervicofacial “lumpy jaw”, post dental work
Thoracic /Pulmonary complications of aspiration pneumonia, present as a “mass lesion” mimicking cancer
Pelvic/Abdominalinfection of intrauterine devices or complications of abdominal surgery


why do mycobacterium not normally take up gram stain? what is the alternative?

they havea very waxy mycolic acid in cell wall; must use acid fast stains


Healthy: Lactobacillus>>>>Gram negative rods
Bacterial Vaginosis: Lactobacillus <<<



what is listeriosis?

foodborne illness- diarrhea and GI sx
Invasive disease (MENINGITIS AND SEPSIS) esp if pregnant (FETAL DEMISE), extremes of age, EtOH abuse, immunocompromised


C perfrigens

spores ubiquitous in the environment, normal flora of GI and vaginal tract
“box car“ Gram smear morphology

Food poisoning- ingest CPE (clostridium perfringens enterotoxin=heat labile) in inappropriately cooked, re-heated or stored food- meat, poultry, gravy…
self limiting GI illness
Gas gangrene- Also caused by C. histolyticum, C. septicum, C. sordelii
Rapidly progressive skin and soft tissue infection, crepitus (gas in tissues), pain out of proportion to findings (deep infection), SHOCK, DEATH within hours if not treated


study slide 36