Quiz 2 (week 3-4)

Question 1

staphylococci

Answer 1

gram pos
facultative anaerobe
non-motile
catalase positive
salt intolerant
normal flora

Question 2

staphylococcus aureus

Answer 2

coagulase positive
most virulent species
protein A - high affinity for IgG inhibits complement cascade
coagulase - converts fibrinogen to fibrin - hides bacteria
bacterial capsule - attachment to surfaces and inhibits phagocytosis
production of enzymes - staphylokinase, coagulase, hyaluronidase, beta-lactamase
production of toxins - hemolysins, TSST, enterotoxins, exfoliative toxins

Question 3

staphylococcus epidermis

Answer 3

normal for flora of skin and mucous
opportunistic pathogen (cause infection in immunocompromised host)
coagulase negative
virulence factors: exopolysaccharide slime
exotoxins

Question 4

staphylococcus saprophyticus

Answer 4

normal flora genitourinary tract
UTI in sexually active young females
coagulase negative
no known exotoxins

Question 5

streptococcus

Answer 5

gram pos cocci
facultative anaerobes
chains or pairs
catalase negative

Question 6

streptococcus pyogenes

Answer 6

not normal flora
GAS
virulence factor: capsule, M Protein, pyrogenic exotoxins, streptokinase, hemolysins, hyaluronidase
pharyngitis, impetigo, cellulitis, necrotizing fasciitis

Question 7

streptococcus agalactiae

Answer 7

group B
virulence factor - capsule
infection most common in neonates, postpartum infection, immunocompromised : bacteremia, endocarditis, pneumonia

Question 8

enterococci

Answer 8

previously classified as group D streptococci
normal flora of GIT and female urogenital tract
virulence factors - adhesion and cytolysins
nosocomial infections - UTI intra-abdominal infections
intrinsically antibiotic resistant
E. Faecium
E. Faecalis

Question 9

streptococcus pneumoniae

Answer 9

α hemolytic
gram pos lancet shaped
diplococci or short chains
normal inhabitants of the upper respiratory tract
bacteremia, meningitis, pneumonia and acute otitis media
polysaccharide capsules
virulence factors: IgA protease, pnemolysin

Question 10

viridans streptococci

Answer 10

α hemolytic and may be non hemolytic
normal flora
opportunistic pathogens and low virulence - bacteremia and endocarditis
virulence factor: extracellular complex polysaccharide

Question 11

corynebacterium

Answer 11

non spore forming
gram pos bacilli - club or irregular shaped
catalase positive
C. diphtheria
other species rarely cause infection

Question 12

listeria monocytogenes

Answer 12

short gram pos motile non spore forming rod or cocobacilli
catalase positive
survive in wide range of env
important food borne pathogen causing listeriosis
virulence factors: adhesion proteins, internalins, listeriolysin O, ActA

Question 13

lactobacillus

Answer 13

non spore forming gram pos rods
usually catalase negative
natural in human vagina important for pH
infections rare found in yogurt

Question 14

bacillus

Answer 14

large gram pos spore forming rods
arranged in chains
aerobic and facultative anaerobic
catalase pos

Question 15

bacillus anthracis

Answer 15

non hemolytic
disease of herbivores
virulence factors: capsule, anthrax toxins (protective antigen, edema factor, lethal factor)
infection = anthrax

Question 16

bacillus cereus

Answer 16

beta hemolytic
motile
opportunistic pathogen
virulence factors: enterotoxins and pyrogenic toxins
food poisoning

Question 17

clostridium

Answer 17

large anaerobic gram pos bacilli
most are motile
catalase neg
decompose proteins or form toxins or both
soil or GIT
spores are wider
C botulinum
C difficile
C perfringens
C tetani

Question 18

gram neg bacteria

Answer 18

gram neg bacilli and coccobacilli

Question 19

enterobacteriaceae

Answer 19

gram neg rods, coliforms
some are part of normal flora and some are pathogenic
non spore forming
grow well on MacConkey agar ( lactose fermenting and non fermenting)
falcultative anaerboes
ferment rather than oxidize glucose
catalase positive
oxidase negative
nitrate -> nitrite

Question 20

E coli

Answer 20

member of the GIT and female genital tract
most are lactose fermenters
virulence factors: endotoxins, pili
diseases: UTI, bacteremia, neonatal meningitis, GIT infections

Question 21

shigella

Answer 21

only found in infections
not normal flora
non lactose fermenters
dysentery

Question 22

salmonella

Answer 22

not part of normal bowel flora
non lactose fermenters
catalase negative
gastroenteritis, enteric fever, bacteriemia

Question 23

acinetobacter

Answer 23

aerobic gram neg
coccobacilli
water soil hospitals
commensals and occasioanlly nosocomial
multidrug resistant

Question 24

pseudomonads

Answer 24

soil and water
motile non spore forming aerobic rods
some form pigments

Question 25

Pseudomonas aeruginosa

Answer 25

major pathogen opportunistic - cause community or hospital acquired infection virulence factors: Pili, exotoxin A, endotoxins, intrinsic resistance to many antimicrobial agents Pyocyanin form biofilms MacConkey Positive oxidase Positive

Question 26

hemophilus

Answer 26

small non motile pleomorphic rods Require enriched media usually containing blood Facultative anaerobes Normally inhabit the upper resp tract of humans

Question 27

H influenzae

Answer 27

type b asymptomatic colonization is uncommon Typeable: based on capsular characteristics non-typable meningitis otitis media pneumonia bacteremia etc non typeable strains usually cause localized infections Virulence factors  Capsule (in encapsulated strains only): antiphagocytic  Pili and other cell surface factors mediate attachment Hib vaccine not effective against non typeable strains MacConkey negative, oxidase variable

Question 28

H ducreyi

Answer 28

Virulence factor: pili, capsular factors, toxins Disease: chancroid (STI) MacConkey negative, oxidase variable

Question 29

Legionella pneumophilia

Answer 29

Gram neg rods that stain poorly Obligate aerobic bacteria motile Fastidious bacilli that require a medium supplemented with iron and L-cysteine virulence factors including genes encoding for the type II secretion systems required for intracellular growth Outbreaks in hospitals have been attributed to the presence of the organism in water taps sinks and showers Person – person transmission has not been documented mild influenza like illness to severe pneumonia legionnaires disease Pontiac fever – lower resp symptoms are less prominent than in legionnaires disease

Question 30

Neisseriae

Answer 30

non motile gram neg diplococci Individual cocci are kidney bean shaped; when the organisms occur in pairs the flat or concave side are adjacent

Question 31

N gonorrhoeae

Answer 31

obligate human pathogen Only found on the mucous membranes of the genitalia eyes rectum and throat at time of infection Virulence factors: pili capsule endotoxin and outer membrane porin STD pharyngitis conjunctivitis

Question 32

N meningitidis

Answer 32

Colonizes oropharyngeal and nasopharyngeal mucous membranes of humans Virulence factors: IgA protease, pili, capsule and endotoxin meningitis and bacteremia