Module 9 part 1 Flashcards
Staph, Strep, and Neisseria
Which is catalase positive or negative: Staphylococcus and Streptococcus
Staph is cat positive and strep is cat negative
What is the alpha, beta, and gamma classification of Streptococcus
hemolysis on a blood agar plate: alpha is partial hemolysis, beta is complete hemolysis, and gamma is no hemolysis
What are Lancefield antigens?
A, B, C, D, E through S. Characteristics of the C carbohydrate
how many species of Strep are human pathogens?
5
What is the Group A Beta Hemolytic Streptococci (GAS)?
Strep pyogenes
what are the antigenic components of the Strep pyogenes cell wall?
C carbohydate and M protein
What is the major virulence factor for GAS?
M protein
What inhibits the activation of complement and protects GAS from phagocytosis?
M protein
What enzymes contribute to GAS pathogenicity?
Streptolysin O and S, pyrogenic exotoxin, and Streptokinase
What antigenic enzyme destroys RBCs and WBCs
Streptolysin O
What enzyme is the principal factor for beta-hemolysis?
Streptolysin S
what toxin is also known as erythrogenic toxin and causes scarlet fever and TSS?
pyrogenic exotoxin
What enzyme activates plasminogen to lyse fibrin clots?
Streptokinase
What helps diagnose strep in the throat?
culture and rapid antigen test
pustule on the extremity or face that breaks down after 4-6 days to form a thick crust
pyoderma
infection of the dermis
erysipelas
Treatment for strep infections
penicillin and clindamycin
How do penicillin and clindamycin treat Strep?
they inhibit the bacterial ribosome and shut down protein syntehsis of pyrogenic toxin and M protein
What disease caused by GAS is a delayed antibody mediated disease?
Rheumatic fever
What disease caused by GAS causes immune responses against M protein that can cross-react with heart tissue due to molecular mimicry?
Rheumatic fever
antibody mediated inflammatory disease of glomeruli that occurs about a week after regular strep infection, where antibody-antigen complexes depossit in kidneys and result in damage from complement and PMN
acute post-streptococcal glomerulonephritis
best antibiotic for GAS pharyngitis
penicillin
antibiotics used for GAS pharyngitis patients who are not compliant with oral meds or have family history of rheumatic fever
1st gen cephalosporins, erythromycin, and azithromycin
What is Group B beta-hemolytic Strep also known as?
Streptococcus agalactiae
What bacteria is most commonly associated with pregnant women and babies?
Group B Strep
3 bacteria most commonly associated with neonatal meningitis
E. coli, Listeria monocytogenes, and group B Strep
Strep mitis, salivarius, mutans, and anginosus are all part of what group?
Viridans
What group of Streptococci represent more than 30% of bacteria from the mouth?
Viridans
What hemolytic group are the viridans streptococci?
alpha-hemolytic
What are the 3 main types of infections resulting from viridans Strep?
dental infections (esp S. mutans), endocarditis (esp subacute bacterial endocarditis, SBE), and abscesses (anginosus group strep)
What 3 bacteria are causes of abscesses?
Anginosus group: S. intermedius, S. constellatus, and S. anginosus
How to remember which bacteria cause abscesses
Strep intermedius and anginosus- immediately assess for abscess
What bacteria can cause subacute bacterial endocarditis?
viridans strep, Staph aureus, and group D strep
2 subgroups of Group D strep
enterococcus and non-enterococcus
What are the enterococcal bacteria?
Enterococcus faecalis and E. faecium
What are the non-enterococcal bacteria?
Strep bovis and Strep equinus
What hemolytic group are enterococci
alpha or gamma
What bacteria are resistant to ampicillin plus aminoglycoside, and now also vanc?
Enterococci
50% of people with S. bovis bacteremia also have what?
colonic malignancy
What group of bacteria grow in bile but not salt?
non-enterococcal Group D strep
what do Strep pneumoniae look like?
diplococci
major virulence factor for Strep pneumoniae
polysaccharide capsule
What are some other virulence factors for Strep pneumoniae?
capsule, pneumolysin, hydrogen peroxide, IgA1 protease, neruaminidase, adhesins
How are Strep pneumoniae identified?
it’s alpha-hemolytic, sensitive to optochin (aka P disc), reactive under Quellung reaction, and lysed by bile acids
Diseases caused by Strep pneumoniae
pneumococcal pneumonia, otitis media, sinusitis, bacterial meningitis
3 major pathogenic Staph species
Staph aureus, epidermidis, and saprophyticus
How to differentiate Staph and Strep
Staph are clustered while Strep is in chains. Staph are catalase positive. Culture is not always most helpful, but Staph aureus is beta hemolytic, golden on SBA, and coagulase positive
what surrounds the peptidoglycan wall of Staph aureus
microcapsule
Protein that binds the Fc portion of IgG and protects bacteria from opsonization
Protein A
protein that leads to fibrin formation around bacteria and protects from phagocytosis
coagulase
proteins that destroy red blood cells, neutrophils, macrophages, and platelets
hemolysins
proteins that destroy leukocytes
leukocidins
secreted form of beta-lactamase that disrupts the beta-lactam ring of penicillin
Penicillinase
protein also called transpeptidase, and necessary for peptidoglycan formation
novel penicillin binding protein (PBP)
protein that breaks down proteoglycans in connective tissue
hyaluronidase
protein that lyses fibirin clots that’s released from Staph
staphylokinase
protein that facilitates Staph aureus colonization in sebaceous glands
lipase
diffusable exotoxin that causes skin to slough off (condition called scalded skin syndrome)
exofoliatin
exotoxins that cause food poisoning
enterotoxins
more deadly analogue to pyrogenic toxin from strep
Toxic shock syndrome toxin 1 (TSST-1)
What are some diseases caused by exotoxin release from Staph aureus?
food poisoning, TSS, scalded skin syndrome
What are some diseases caused by direct organ invasion of Staph aureus?
pneumonia, meningitis, osteomyelitis, acute bacterial endocarditis, septic arthritis, skin infection, bacteremia/sepsis, and UTIs
sudden-onset/acute endocarditis results from what bacteria?
Staph aureus
2 skin infections caused by Strep pyogenes and Staph aureus
cellulitis and impetigo
folliculitis that penetrates into subcutaneous tissue
Furuncle
Even worse version of a furuncle
carbuncle
Common bacteria causing catheter infections
Staph aureus
What do staphylococci secrete that makes them penicillin resistant?
penicillinase
What gives Staph aureus methicillin resistance?
acquisition of a chromosomal DNA segment, mecA, that encodes for a new PBP 2A
How does MRSA pass its resistance genes?
via transposons
What treats MRSA?
Vanc
What causes community acquired MRSA?
Panton-Valentine Leukocidin (PVL) toxin that causes skin abscesses
What do VISA and VRSA stand for?
Vancomycin intermediate Staph aureus and Vanc resistant Staph aureus
what indicates resistance of Staph aureus to all glycopeptide antibiotics?
VISA
MIC for VISA
8-16 micrograms/mL
MIC for VRSA
more than 32 micrograms/mL
modified DNA transposon found in VRSA
vanA
What bacteria is normally found on the body, responsible for biofilms on catheters, IVs, implants, and prostheses?
Staph epidermidis
Difference in identifying Staph aureus vs epidermidis
Staph epidermidis is coagulase neg
Second most common cause of UTIs in women
Staph saprophyticus
Only pathogenic gram-neg cocci
Neisseria
What do Neisseria look like?
diplococci, and each are shaped like kidney beans
2 pathogenic species of Neisseria in humans
Neisseria meningitidis and gonorroheae
virulence factors for Neisseria meningitidis
capsule, endotoxin (LOS), IgA1 protease, pili
infectious serogroups of N. meningitidis
A, B, and C
High risk groups for Neisseria meningitidis
infants 6 months to 2 years, army recruits, and college freshmen
How does Neisseria meningitidis spread
via respiratory secretions from an asymptomatic person’s nose
particular symptom special for meningococcemia
petechial rash
Type of meningitis with septic shock, adrenal hemorrhage and insufficiency, rapid hypotension, tachycardia and petichiae
fulminant meningococcemia
2 bacterai that cause meningitis later in life
Neisseria meningitidis and Haemophilus influenzae
Classic medium for Neisseria culture
Thayer Martin VCN media
What is Thayer Martin VCN media?
chocolate agar with antibotics: vancomycin, colistin (kills gram neg except neisseria) and Nystatin (kills fungi)
treatment for meningococcus
Penicillin G or ceftriaxone
second most commonly transmitted sexual infection
gonorrhoea
Virulence factors for Neisseria gonorrhoeae
Pilus, outer membrane protein porins (PorA and PorB), Opa proteins
symptoms of gonococcal disease in men
urethritis, epididymitis, prostatitis, urethral strictures
treatment for gonorrhea
ceftriaxone
symptoms of gonococcal disease in women
burning during urination and prurulent urethral discharge
What can gonococcal infection progress to in women?
PID, including endometritis, salpingitis, and oophoritis
complications of PID
sterility, ectopic pregnancy, abscesses, peritonitis, peri-hepatitis
Symptoms of gonococcal infection in infants
opthalmia neonatorum (gonococcal conjunctivitis) which can damage the cornea and cause blindness
How are neonatal gonorrhea and chlamydia eye infections treated?
erythromycin eye drops
Treatment for gonococcal infections
Penicillin G and sulfonamides previously, now often ceftriaxone and single dose of azithromycin
