Clinical Microbiology Exam 2 Flashcards
Where is Erysipelothrix rhusiopathiae normal flora?
- Found worldwide
- Pathogen in domestic swine, birds, and fish
Gram-Positive Cocci can be separated into two groups based on what test?
Coagulase Test
Virulence factors of Staph epidermidis
Biofilm production
Infections caused by Corynebacterium species
- May cause disease in the immunocompromised individuals
What are virulence factors of Bacillus anthracis?
- Protective antigen (PA) – binding molecule
- Edema factor (EF) – causes edema
- Lethal factor (LF) - kills host cells
What test(s) distinguish Bacillus cereus?
- Motile
- Hemolytic on BAP
- Resistant to penicillin
Where is Bacillus anthracis normal flora?
- Commonly found in soil
Infections caused by Erysipelothrix rhusiopathiae
- Human cases usually occupational exposure – enter
through cuts or scratches on the skin - Erysipeloid – localized skin disease
- Septicemia associated with endocarditis
- Cutaneous infection
What test(s) distinguish Corynebacterium species?
- Catalase-positive
- Nonmotile
Where is Lactobacillus species normal flora?
Widely distributed in nature and foods, as well as in normal biota in the human mouth, GI tract, and female genital tract
What tests distinguish Strep agalactiae?
Infections caused by Staph lugdunensis
Endocarditis, septicemia, meningitis, skin and soft tissue infection, urinary tract infection, septic shock. Can mimic S. aureus infection.
What test(s) distinguish Lactrobacillus species?
- Vancomycin resistant
- Penicillin susceptible
- Alpha-hemolytic on BAP
- Catalase negative
What are the three groups of GPB?
Tests distinguishing Staph lugdunensis
Slide coagulase – sometimes positive
Tube coagulase - negative
PYR - positive
Ornithine decarboxylase – positive
Where is Strep pyogenes normal flora?
Infections caused by Corynebacterium diphtheriae
- Nonhealing ulcers
- Respiratory Diphtheria
Where is Gardnerella vaginalis normal flora?
- Normal flora in urogenital tract
Infections caused by Staph epi
Hospital acquired urinary tract infections (UTI). Infection associated with IV catheters, CSF shuts, prosthetic joints, and prosthetic heart valves
What test(s) distinguish Corynebacterium diptheriae?
- Catalase-positive
- Nonmotile
What are the two groups Gram-Positive Cocci can be separated into?
- Bound coagulase
- Free coagulase
- Staphylococci can produce both, one, or neither
type of coagulase
What test(s) distinguish Arcanobacterium species?
- Catalase-negative
- Positive for CAMP inhibition test
- Phospholipase D produced by Arcanobacterium inhibits β-hemolysis produced by S. aureus
- Drug of choice – erythromycin
- Penicillin resistant
What are virulence factors of Corynebacterium diphtheriae?
- Produced in strain infected with
lysogenic β-phage carrying the tox
gene for diphtheria toxin - Able to block protein synthesis
in human cells causing cell death - Causes both localized and
systemic damage
What tests distinguish Strep pneumoniae?
Optochin susceptible
Soluble to bile salts
Where is Corynebacterium diphtheriae normal flora?
- Cutaneous Diphtheria is found in the tropics
Infections caused by Lactobacillus species
- Systemic infections are rare
- Usually in immunocompromised patients
Infections caused by Staph aureus
Skin and wound infections (Folliculitus, Furuncles, Carbuncles, Bullous impetigo). Scalded skin syndrome (Ritter disease). Toxic Shock syndrome. Food poisoning. Bacteremia. Osteomyelitis. Pneumonia.
Virulence factors of Staph aureus
- Enterotoxins
- Toxic Shock Syndrome Toxin-1 (TSST-1)
- Exfoliative toxin
- Cytolytic Toxins
- Coagulase - clotting
- Protease – breaks down proteins
- Hyaluronidase – attacks cartilage
- Lipase – breaks down lipids
- Protein A – binds IgG, Hides bacterial cell from immune system
Infections caused by Strep pnuemoniae
- Pneumococcal pneumonia
- Bacterial meningitis
- Also causes sinusitis and otitis media
Bacteremia
Virulence factors of Staph saprophyticus
- Adheres more effectively than other pathogens to the lining of the urogenital tract
Infections caused by Strep agalactiae
- Neonatal Streptococcal Disease
- In adults:
- Endometritis and wound infections in young, previously
healthy women who become ill after childbirth or
abortion - Infection in elderly person with a serious underlying
disease or immunodeficiency - Common cause of infection in diabetic foot ulcers
Tests distinguishing Micrococcus species
Catalase-positive
Modified oxidase (microdase) - pos
Infections caused by Strep pyogenes
- Bacterial Pharyngitis (Strep throat)
- Scarlet fever
- Pyodermal Infections (Skin infections)
- Impetigo
- Erysipelas
- Necrotizing Fasciitis (“Flesh-eating disease”)
- Rheumatic fever (Within 1 month of StrepThroat)
- Acute glomerulonephritis (Following cutaneous infection or Strep Throat)
Where is Bacillus species normal flora?
- Commonly found in soil
What test(s) distinguish Gardnerella vaginalis?
- Catalase – negative
Where is Strep, viridans group normal flora?
- Upper respiratory tract
- Female genital tract
- Gastrointestinal tract
Tests distinguishing Staph saprophyticus
Slide and tube coagulase:
* Negative
Novobiocin resistant
Where is Strep pneumo normal flora?
Infections caused by Listeria monoctyogenes
- Uncommon but serous infection in neonates, pregnant women, elderly, and immunocompromised
- Meningitis and endocarditis in immunocompromised patients
- Food poisoning
Virulence factors of Strep pyogenes
Infections caused by Staph saprophyticus
UTIs
Where is Corynebacterium species normal flora?
- Most species part of normal skin and mucous membrane flora
Tests distinguishing Staph epidermidis
Slide and tube coagulase - negative
What test(s) distinguish Listeria monocytogenes?
- Catalase – positive
- Motility:
- Tumbling on wet prep
- “Umbrella” motility in test medium at 25°C
- CAMP – positive
- Hippurate hydrolysis – positive
- Bile esculin hydrolysis - positive
What test(s) distinguish Bacillus anthracis?
- Nonmotile
- Susceptible to penicillin
- Produces lecithinase on egg-yolk agar
Infections caused by Gardnerella vaginalis
- Bacterial vaginosis (BV)
- May also cause UTIs in both men and women
What tests distinguish Strep, viridans group?
What tests distinguish Strep pyogenes?
Infections caused by Arcanobacterium species
- Pharyngitis
- In patients 10 to 20 years old
- Often indistinguishable from pharyngitis caused by Strep. pyogenes
- 50% develop pruritic scarlatiniform rash and desquamation of hands and feet
Also associated with soft tissue infection, sepsis, and endocarditis
Virulence factors of Step pneumo
Tests distinguishing Staph aureus
Coagulase testing
results:
* Free – positive
* Bound – positive
Latex agglutination test to detect protein A
Infections caused by Strep, viridans group
- Opportunistic pathogens
- S. mitis group most common cause of bacterial endocarditis
- Abscess formation in the oropharynx, brain, and
peritoneal cavity
Where is Strep agalactiae normal flora?
What test(s) distinguish Erysipelothrix rhusiopathiae?
- Nonmotile
- Catalase-negative
- Produces H2S
- “Test tube brush-like” pattern in gelatin at 22°C
Where is Listeria monocytogenes normal flora?
- Soil, water, vegetation, and animal products
Infections caused by Bacillus anthracis
Cutaneous anthrax – 99% of anthrax cases in the
world.
Inhalation anthrax (Woolsorter’s disease).
Gastrointestinal anthrax - <1% of cases; never in
US.
Injectional anthrax.
Infections caused by Bacillus cereus
Food poisoning (Diarrheal or Emetic).
Eye infections
What test(s) separate GPB into three groups?
Infections caused by Micrococcus species
very rarely a pathogen
