GRAM + Flashcards
Catalase +, Coagulase +
Staphylococcus aureus
Catalase +, Coagulase -, Novobiocin sensitive
Staphylococcus epidermis
Catalase +, Coagulase -, Novobiocin resistant
Staphylococcus saprophyticus
Catalase -, a hemolytic, Optochin sensitive
Streptococcus pneumoniae
Catalase -, a hemolytic, Optochin resistant
Streptococcus viridans
Catalase -, B hemolytic, Bacitracin sensitive
Streptococcus pyogenes (GAS-Group A Strep)
Catalase -, B hemolytic, Bacitracin resistant
Streptococcus agalactiae (GBS-Group B Strep)
Catalase -, non-hemolytic, 6.5% NaCl growth
Enterococcus
Aerobic
Spore forming
-spores form when nutrients are limited
-Dipiccolonic acid–>pushes H2O out; autoclave with steam
Bacillus spp.
Obligate anaerobe (Lack superoxide dismutase)
Spore forming
-spores form when nutrients are limited
-Dipiccolonic acid–>pushes H2O out; autoclave with steam
Clostridium spp.
Non-spore forming bacillus
Listeria monocytogenes or Corynebacterium diptheriae
Beaded filament, not acid fast, obligate anaerobe, spore forming
Actinomyces israelii
Beaded filament, weakly acid fast, obligate aerobe, spore forming
Nocardia asteroides
Staphylococcus aureus
Catalase +, Coagulase +
***Mayonnaise
Protein A=antiphagocytic (inhibits Fc-IgG binding)
TSST-1=superantigen causes toxic shock
Exfoliatins=skin sloughing/Scaled Skin Syndrome
Enterotoxins=vomiting/diarrhea
Skin infxn (MSSA, MRSA) Scaled skin syndrome Toxic shock syndrome Food poisoning Pneumonia Osteomyelitis Endocarditis
Staphylococcus epidermis
Catalase +, Coagulase -, Novobiocin sensitive
***Intracorporeal devices, catheters, lines, prosthetics, etc. for >3 months
Staphylococcus saprophyticus
Catalase +, Coagulase -, Novobiocin resistant
***Honeymoon cystitis–>UTI
(Not an STI but is part of normal vaginal flora, and can cause UTI due to sexual intercourse)
Streptococcus pneumoniae
Catalase -, a hemolytic, Optochin sensitive
***Rusty, brown sputum
IgA Protease
Encapsulated (+Quellung reaction)
Pneumonia (in adults and elderly)
Bacterial meningitis in children and elderly
Bacterial otitis media
Bacterial sinusitis
Streptococcus viridans
Catalase -, a hemolytic, Optochin resistant
***Infection after dental procedure (normal flora in mouth)
“No No Bug”
- No capsule
- Not soluble in bile
- Not sensitive to optochin
Streptococcus pyogenes
Catalase -, B hemolytic, Bacitracin sensitive
Group A Strep
***ASO titers
M protein (prevents C3b binding; cross reactivity causes thematic fever)
**Impetigo
**Bacterial pharyngitis (“strep throat”)
Toxic shock-like syndrome
Erythematous infection
Scarlet fever
Necrotizing fasciitis
**Rheumatic fever–>heart disease
**Acute Poststreptococcal glomerulonephritis
Streptococcus agalactiae
Catalase -, B hemolytic, Bacitracin resistant
Group B Strep
***Normal vaginal flora–>think: BABIES
Neonatal meningitis
Neonatal sepsis
Neonatal bacterial pneumonia
Enterococcus faecalis/faecium
Catalase -, non-hemolytic, 6.5% NaCl growth
***Bladder cancer pts
Subacute endocarditis in bladder cancer pts or abdominal surgery pts
Streptococcus bovis
Catalase -, non-hemolytic, NO growth in 6.5% NaCl
***Colon cancer pts
Sepsis and subacute endocarditis in colon cancer pts
Bacillus cereus
Spore forming, aeorobic
Fried Rice Syndrome
Heat Stable toxin–>Vomiting (within 6 hrs)
Heat Labile toxin–>Diarrhea (within 6 hrs)
Very difficult to distinguish Bacillus cereus vs enterotoxin of Staphylococcus aureus
Bacillus anthracis
Spore forming, aeorobic
- **Boxcars
- **Hilar lymphadenopathy and mediastinal widening
Polypeptide capsule (unique to this organism)
EF (Edema Factor)=adenylate cyclase–>increase in cAMP–>water homeostasis imbalance
LF (Lethal Factor)=metalloproteinase that kills macrophages
PA (Protective Antigen)=require for EF and LF to function
Cutaneous anthrax: spore contact–>painless ulcer–>black eschar (w/ swelling)–>bacteremia–>death
Pulmonary anthrax: inhalation of spores–>flu-like symptoms–>pulmonary hemorrhage and mediastinitis (hilar lymphadenopathy and mediastinal widening)–>shock/ARDS
Clostridium tetani
Obligate anaerobe (Lack superoxide dismutase)
Spore forming
***Deep tissue wounds–> ↑contractility/spasms
Tennis racket/drumstick shaped
Tetanospasmin toxin=inhibits release of INHIBITORY GABA and glycine–>SPASM
Presentation:
- Trismus (aka Lockjaw)
- Facial spasms
- Opisthotonus (aka Back arching)
- Sympathetic overactivity (fever, sweating, tachycardia, labile HTN)
Clostridium botulinum
Obligate anaerobe (Lack superoxide dismutase)
Spore forming
***Improper food prep/canned foods…HONEY
Heat labile toxin A=inhibits release of EXCITATORY ACh–>PARALYSIS
Classic tetrad:
- Descending weakness with flaccid paralysis
- CNs affected first (bulbar weakness)
- No fever
- No mental status changes
Also causes Floppy Baby Syndrome
-Due to anticholinergic symptoms–>constipation (1st), lethargy, difficulty feeding, change in crying pitch of baby
Clostridium difficile
Obligate anaerobe (Lack superoxide dismutase)
Spore forming
***Antibiotic associated diarrhea (esp. with CLINDAMYCIN and ampicillin, but some other broad spectrum antibiotics)
A toxin=Enterotoxin–>Binds to brush border causing diarrhea
B toxin=Cytotoxin–>Destroys cytoskeleton causing pseudomembranous colitis
Tx: Metronidazole, Vancomycin, poop transplant
Clostridium perfringens
Obligate anaerobe (Lack superoxide dismutase)
Spore forming
Only member of Clostridium spp. that is NON-MOTILE
***Gas gangrene
α toxin=Lecithinase–>breaks down cell membranes
“Double-zoned” hemolysis on blood agar
Gas gangrene/myonecrosis
- Red/purple skin that looks like cellulitis
- Bullae
- Crepitus felt on skin
Listeria monocytogenes
Non-spore forming bacillus, motile
INTRACELLULAR; still motile using actin to transfer between cells (“actin rockets”)
LPS endotoxin=can cause fever, shock
Neonates–>normally in vagina, so can cross placenta and cause abortions; also, granulomatosis infantiseptica
Elderly–>Meningitis
Corynebacterium diphtheria
Non-spore forming bacillus, non-motile
***Pseudomembrane on pharynx
“Chinese letter” appearance
Diphtheria toxin=AB toxin=ADP ribosylation of EF-2–>inhibits protein synthesis
+ Elek’s test
Growth of black colonies on potassium tellurite agar
Pseudomembrane on pharynx with fever
Myocarditis–>EKG changes
Polyneuritis–>targets local nerves–>CNs–>laryngeal nerves
Actinomyces israelii
Beaded filament, not acid fast, obligate anaerobe, spore forming
Normal oral flora, GI tract, and female GU tract–>usually opportunistic or after surgery (or IUDs)
***Yellow sulfur granules
Oral/facial abscesses with draining sinuses–>can go on to form GI and lung abscesses
Nocardia asteroides
Beaded filament, weakly acid fast, obligate aerobe, spore forming
Opportunistic
Slowly progressive pneumonia–>abscesses in kidney or brain (encephalitis)
[Similar to TB in that it’s acid fast, but differentiated due to beaded, filamentous growth]
