Streptococci II Flashcards
Streptococcus agalactiae
Hemolysis
Bacitracin susceptibility
Group type
Beta-hemolysis
Bacitracin resistance
Group B
What patient population most commonly gets infected with Strep agalactiae?
Women in peripartum period and in newborns
What 3 ways does early-onset neonatal Strep agalactiae infection present?
- Bacteremia without an identifiable focus
- Pneumonia
- Meningitis
How does late onset neonatal Strep agalactiae infection present?
Bacteremia w/ meningitis
How does maternal Strep agalactiae usually manifest?
Complication of pregnancy (endometritis and/or wound infection after Cesarian)
What types of adult individuals typically develop group B strep disease (besides peripartum women)?
People with underlying illnesses (diabetes is most common)
Are Group B strep susceptible to penicillin?
Yes
Streptococcus gallolyticus (bovis)
Group type
Hemolysis
Penicillin sensitivity
Group D
Gamma-hemolysis
Penicillin sensitive
Diseases associated with Strep gallolyticus
Bacteremia & endocarditis due to lesions from mouth to anus, but adenocarcinoma of colon is strongest
What procedure must you perform on patients who have S. gallolyticus bacteremia or endocarditis?
Colonoscopy to screen for cancer
Enterococcus faecalis & E. faecium
Group type
Hemolysis
Penicillin sensitivity
Associated diseases
- Group D
- Gamma-hemolysis
- Tolerant (penicillin will kill it, but you’d need a LOT of it)
- Endocarditis, UTI’s, meningitis as a result of surgery or strongiloides
What Group D bacteria constitute substantial portion of normal bowel flora?
Enterococcus
T or F. Enterococci are not as intrinsically virulent as other strep.
TRUE - usually cause infections in areas that have been previously damaged
What types of patients normally get enterococcal infections? Why?
Hospitalized patients - can be transferred on hands of health care personnel, can survive for prolonged periods in inanimate environment, surgery & invasive procedures as well as prior antibiotic therapy predispose to colonization
What streptococcus species are sexually promiscuous? How is this advantageous?
Enterococci - means they gain lots of abilities for antibiotic resistance
What mechanisms do enterococci have that provide them with resistance to a # of antibiotics?
- High-level aminoglycoside resistance
- Alterations of penicillin-binding proteins
- Beta-lactamase production
- Vancomycin resistance due to altered terminal D-ala D-ala on peptidoglycan side chain
For Group C and Group G strep, what types of patients are commonly infected?
Those with underlying diseases
- S. mitis
- S. sanguis
- S. salivarious
- S. mutans
Group Hemolysis Optochin susceptibility Bile salts solubility Associated diseases
- Viridans streptococci
- alpha-hemolytic
- Optochin resistant
- Insoluble in bile salts
- Dental caries, most common cause of infective endocarditis, meningitis
- S. anginosus
- S. constellatus
- S. intermedius
Group
Hemolysis
Oxygen use
Associated diseases
Strep anginosus or Milleri group
Gamma-hemolysis
Microaerophilic streptococci that cause abscesses, infective endocarditis (very very rare) - normal constituents of human bowel that cause disease when they spread to normally sterile areas through blood or directly
Fish pathogen - causes subcutaneous abscesses in Amazon freshwater dolphins and fishponds
Streptococcus iniae
Peptococcus, Peptostreptococcus
Anaerobic strep that are normal constituents of microbial flora of GI and female GU tract, cause problems when they end up in normally sterile locations b/c of altered anatomy, poorly perfused tissues, or trauma
What antibiotics would you treat Enterococcus infection with and why?
Ampicillin + gentamicin (penicillin + aminoglycoside)
Penicillin is the drug of choice, but you’d need a LOT of it for it to work, so create a synergy effect by adding aminoglycoside
