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Micro1 Strep & Staph

Microbiology 1 Staph and Strep test - DelTech Owens Campus

QuestionAnswer
Staphylococci are catalase-(pos or neg?) and gram positive. catalase-positive
What is the primary pathogen in the genus Staphylococcus? S. aureus
S. aureus is often identified by being coagulase-(pos or neg?). coagulase positive
What types of skin infections is S. aureus known to cause? 1) impetigo 2) bullous impetigo 3) furuncles/boils 4) carbuncles 5) mastitis 6)cellulitis 7) wound infections
What types of deeper tissue infections is S. aureus known to cause? 1)pneumonia 2) organ absesses 3) bacteremia 4) endocarditis 5)osteomyelitis 6) septic arthritis
How does protein A make S. aureus more virulent? It binds to the Fc portion of IgG and therefore resists phagocytosis
What toxin causes toxic shock syndrome? Mainly TSST-1, but some have been linked to enterotoxin B or C
What toxin causes scalded skin syndrome? Exfoliative toxin or epidermolytic toxin
What toxins cause staphylococcal food poisoning? Enterotoxins A-J except for F.
Of the enterotoxins that cause food poisoning, which are the most common culprits? A, B, and D
Coagulase-negative staph are considered clinically significant if they are associated with what 3 things? indwelling devices, UTI, present in immunocompromised patient
What 2 coagulase-negative staph are considered more significant and need to be identified to the species level? S. epidermidis and S. saprophyticus
What 2 types of coagulase are produced by aureus? 1. cell bound coagulase (also called clumping factor) 2. free coagulase (also called extracellular coagulase)
How can cell-bound coagulase be detected in the lab? slide coagulase and latex slide agglutination assays
How can free coagulase be detected in the lab? tube coagulase method
How can S. aureus be differentiated from most other staph isolates? positive for coagulase
How can S. saprophyticus be differentiated from other staph? Novobiocin disk diffusion: saprophyticus is resistant, while most other coagulase-negative staph are susceptible.
What kind of antibiotic is recommended to detect MRSA? cefoxitin
What is the most accurate test to check if a staph is MRSA? molecular tests for mecA or latex agglutination tests for PBP2
How can a lab check for clindamycin resistance? D test - a disk diffusion test using both clindamycin and erythromycin that forms a D-shaped zone of inhibition when positive
What is the recommended treatment for MRSA? vancomycin
Staphylococci are spherical shaped under a microscope. These cells appear in what 3 ways when viewed through the ocular? 1. singly 2. pairs 3. clusters
Micrococci, which resemble staph in some ways, are catalase (pos or neg?). positive
Staph are catalse (pos or neg?). positive
Micrococci are coagulase (pos or neg?). negative
Micrococci are often found in the ? environment and as indigenous skin biota
Micrococci are bacitracin susceptible. Staphyolococci are bacitracin (resistant or susceptible?). resistant
What kind of staph can be found in the inner ear? Alloiococcus otitis
Which kind of staph is an obligate anaerobe? S. saccharolyticus
What colors are typical of staph colonies grown on a dish? 1. cream 2. white 3. buttery (rare)
Small-colony variants of staph may require one of what 3 things to grow? 1. CO2 2. hemin 3. menadione
S. pneumonia is __-hemolytic and requires what sort of environment to grow? beta-hemolytic and CO2 to grow
What is the active enzyme in a coagulase test? Staphylocoagulase
Another enzyme, known as __ __ can produce effects similar to coagulase. clumping factor
Most staph that produce clumping factor are isolated from __ specimens. animal
Most coagulase-positive isolates from human sources are considered to be ? S. aureus
What 3 toxin-induced diseases are frequently associated with S. aureus? 1. food poisoning 2. scalded skin syndrome 3. toxic shock syndrome
S. epidermidis and S. saprophyticus are 2 clincally important CoNS staph. Name 2 more that are of growing concern. S. haemolyticus and S. lugdunensis
More than (how many?) species of coagulase-negative staph (CoNS) are recognized to exist? 40
Staph enterotoxins can remain stable at (what temperature?) and for (how long?). 100 C for 30 mins
Which 4 enterotoxins are associated with toxic shock syndrome? B, C, G and I (especially B and C)
Which enterotoxin has been associated with staphylococcal pseumdomenbranous enterocolitis? B
TSST-1 stands for ? toxic shock syndrome toxin-1
TSST-1 is a __ that can interact with T cell and cause a massive, nonspecific immune response. superantigen
What is the cause of nearly all menstruating-associated toxic shock syndrome and half of all nonmenstruating associated TSS? TSST-1
At a low concentration, TSST-1 causes __ of endothelial cells. leakage
At a high concentration, TSST-1 is __ to endothelial cells. cytotoxic
What kind of toxin causes the skin to slough off and is known cause scalded skin syndrome? exfoliative toxin
Exfoliative toxin is also known as ? Ritter disease
What other kind of skin condition is associated with exfoliative toxin? bullous impetigo
What are the 4 hemolysins produced by Staph? 1. alpha-hemolysin 2. beta-hemolysin 3. gamma-hemolysin 4. delta-hemolysin
Which hemolysin causes damage to platelets and macrophages? alpha
Which hemolysin is often associated with PVL (Panton-Valentine leukocidin)? delta
Which hemolysin is also called the "hot-cold" lysin? beta
Which hemolysis does the least damage to blood cells? gamma
Which hemolysin is exhibited in the CAMP test to ID group B streptococci? beta
What kind of exotoxin secreted by some strains of S. aureus is lethal to segs (WBCs)? Staphylococcal leukocidin (also called PVL or Panton-Valentine leukocidin)
Besides helping S. aureus evade phagocytosis, what else does PVL do to the patient? cutaneous infections and necrotizing pneumonia
Which enzyme, produced by S. aureus, hydrolyzes hyaluronic acid? hyaluronidase
Lipases act on __ on the surface of the skin. lipids
Although it can be found elsewhere in the body, what is the primary reservoir for staph in the human body? nares
MRSA stands for? Methicillin-resistant Staphylococcus aureus
Once S. aureus has breached the barriers to infection, it activates the host's ? acute inflammatory response
Skin infections caused by S. aureus are __ and usually occur due to previous injuries. suppporative (pus filled)
What do you call a mild inflammation of a hair follicle or oil gland? folliculitis
Carbuncles occur when larger lesions develop from multiple ? furuncles
Scalded skin syndrome occurs most often in what 2 groups of people? newborns and once healthy young people
Scalded skin syndrome occurs most commonly in patients with what 2 conditions? 1. chronic renal failure 2. compromised immune system
The mortality rate of children with SSS is low, but in adults, it's about __ percent. 50
Toxic shock syndrome is characterized by sudden onset of what 6 symptoms? 1. fever 2. chills 3. vomiting 4. diarrhea 5. muscle aches 6. rash
What are the lab findings in toxic shock syndrome? 1. high WBC count - especially bands and metamyelocytes 2. low platelets 3. DIC 4. high serum creatinine 5. high urea
TEN stands for ? toxic epidermal necrolysis
TEN is very similar to what other condition? scalded skin syndrome
The treatment for TEN and for SSS is different in what way? Steroids help tend by worsen SSS
What infection is known to occur secondarily to influenza? Staphylococcal pneumonia
S. pneumonia is characterize by multiple __ and focal __ in the pulmonary __. multiple abscesses, focal lesions, pulmonary parenchyma
Infections causes by S. epidermidis are primarily ? nosocomial
What form of endocarditis is often caused by S. epidermidis? prosthetic valve endocarditis
Which kind of staph infection is the most common cause of UTIs in women and adheres to epithelial cells better than other CoNS? S. saprophyticus
Ideally, clinicians should collect how many swabs when requesting a gram stain and culture? 2
What is the best type of sample? aspirate
Which is more likely to produce hemolytic zones on an SBA: S. aureus or S. epidermidis? aureus
What type of reaction differentiates a colony of staph from a colony of micrococci? oxidation-fermentation reactions produced on O/F glucose media
Staph ferment __, while micrococci fail to produce acid under anaerobic conditions. glucose
A modified oxidase test like the __ __ can be used to rapidly differentiate staph from microc. Microdase disk
Staphylocoagulase reacts with a thermostable, thrombin-like molecule called ? coagulase-reacting factor (CRF)
When checking for CRF complexes, you should look for a clot to form after how many hours and incubated at what temp? 4 hours, 37C
If no clot forms after 4 hours when searching for CRF complexes, what should you do? Leave the tube at room temp (to avoid false negatives) and check the following day
Most S. aureus isolates are resistant to penicillin because they produce ? beta-lactamases
What kind of agar plate can be used to screen for MRSA? oxacillin-salt agar plate
BORSA stands for? borderline oxacillin-resistant S. aureus
When screening for MRSA isolates in a colony, how can you tell the MRSA from the non-MRSA? MRSA will grow more and turn color
What is the "gold standard" for detecting MRSA? detection of the mecA gene
What are the most common strains of community acquired MRSA? USA 300 and USA 400
VISA (not the credit card) stands for? vancomycin-intermediate S. aureus
VRSA stands for what? vancomycin-resistant S. aureus
How do you screen for VRSA or VISA? vancomycin agar plate
Clindamycin is a __, a drug that is bacteriostatic or even bacteriocidal in high doses. macroglide
Streptococci and Entercocci are both in the family Streptococcaceae. How can you tell them apart? catalase test
Colonies of Streptococci and Enterococci are usually small and somewhat ? transparent
A wide-zone of hemolysis surrounding a zone of no-hemolysis near a strep culture is called ? wide-zone or alph-prime hemolysis
Strep. pyogenes belongs to which Lancefield group? A
What is the best-defined virulence factor in Strep. pyogenes? M protein
M protein in Strep. pyogenes is encoded by __ genes. emm
The M protein causes a streptococcal cell to resist __ and helps it adhere to mucosal cell. phagocytosis
Strepolysin O lyses __ and __ among other cells. leukocytes and platelets
The hemolysis seen around colonies that have been incubated aerobically is due to ? streptolysin S
Some strains of Strep. pyogenes cause a red rash that spreads over the body called ? scarlet fever
The real cause of scarlet fever is ? streptococcal pyrogenic exotoxins (Spes)
Spes function as ? superantigens
Infections caused by Strep. pyogenes include what 5 things? 1. pharyngitis 2. scarlet fever 3. skin/pyodermal infections 4. rheumatic fever 5. acute glomerulonephritis
The 2 most common clinical manifestations of group A streptococcal infections are ? 1. pharyngitis 2. tonsillitis
"Strep throat" is spread by __ and __ __. droplets and close contact
About 1/3 of those complaining of sore throat have a throat culture positive for ? S. pyogenes
Necrotizing fasciitis is most commonly associated with which group of streptococcus? A
Type 1 necrotizing fasciitis is a polymicrobial infection from which __ and __ bacteria are recovered. aerobic and anaerobic
Type 2 necrotizing fasciitis is caused only by group __ streptococci. A
Type 3 necrotizing fasciitis is gas __ and clostridil __. gas gangrene and clostridial myonecrosis
A variant of type 1 NF is called ? saltwater NF
A condition caused by streptococci wherein the entire organ system can shut down, leading to death, is called ? streptococcal toxic shock syndrome
2 serious complications of group A strep. disease include ? 1. rheumatic fever 2. acute glomerular nephritis
The favored treatment for group A streptococci is __, although __ may also be used. penicillin, erythromycin
Care should be taken to avoid touching the ___ and __ with the swab when getting a sample of strep from the mouth. tongue and uvula
An SBA plate with strep on it should be incubated at what temperature? 35C
An SBA containing what is recommended for better recovery of beta-hemolytic strep from throat cultures? sulfamthoxazole
3 key tests for strep include ? 1. Lancefield 2. bacitracin 3. PYR
All strains of Strep. agalactiae have the group __-specific antigen. B
The capsule of group B strep prevents phagocytosis but is ineffective after ? opsonization
Group B strep infections often present as __ or __ with bacteremia. pneumonia or meningitis
All pregnant women should be screened for group B strep at __ to __ weeks gestation by getting a vaginal and rectal swab sample. 35 to 37
Group B strep grow on SBA as __ __ __ colonies with a small zone of beta-hemolysis. grayish white mucoid
The most useful test for group B strep include ? 1. hippurate 2. CAMP
Large colony forming isolates of streptococci with groups A, C, and G antigens are classified with ? pyogenic streptococci
What is the antigen in the cell wall of Strep. pneumoniae called? It is similar to the C carbohydrate on the Lancefield groups. C substance
What reacts with the C substance in the cell walls of pneumoniae/pneumococcus to form a precipitate? C-reactive protein
The pneumoniae/pneumococcus capsule is antigenic and can be detected with antisera in the __ test. Neufield
What do you call it when the pneumoniae capsule swells in the presence of specific anticapsular serum? Quellung reaction
What is the number one cause of bacterial pneumonia? Strep. pneumoniae
What are the names of the 2 pneumococcal vaccines and what groups are they given to? PCV7 (given to children) and PS23 (given to adults)
Pneumococcal colonies appear to be __ in formation under a microscope. diplococci
What sort of media is best for growing isolates of Strep. pneumococcus? 1. brain-heart transfusion agar 2. trypticase soy agar with sheep RBCs 3. chocolate agar
Some pneumococcal isolates require what kind of gas for growth? CO2
How can you tell Strep. pneumococcus from viridans streptococci? 1. Optochin diffusion (susceptible) 2. bile solubility (they are bile soluble)
How are Strep. pneumococcus infections treated? 1. penicillin 2. erythromycin 3. chloramphenicol
What is the most common cause of subacute bacterial endocarditis? Viridans streptococci
Besides blood stream infections, what are common oral problems caused by viridans? cavities and gingivitis
Viridans infections are treated with ? penicillin
Viridans are the most common isolates associated with bacterial __ and in both native and prosthetic __ infections. endocarditis, valve
The presence of __ (a viridan) has a high correlation with gastrointestinal carcinoma. gallolyticus
Which viridan is most commonly isolated from the oral cavity and is the primary contributor to oral cavities? Strep. mutans
Which streptococci groups possess the M protein? A, C, G
All viridan streptococci are PYR __ and LAP __. PYR negative and LAP positive
The lack of what separates the viridans streptococci from groups A, B, C, and G? beta-hemolysis
Which viridan - when beta-hemolytic - forms a zone of hemolysis that is several times the size of the colony? S. anginosus
Group D streptococci can be separated from Enterococcus with the __ test. PYR (D is negative while Enterococcus is positive)
Group D strep is susceptible to __ while Enterococcus is resistant. penicillin
All species of enterococci produce the cell wall-associated group __ antigen in the Lancefield classification system. D
The ability of enterococci to hydrolyze what can be used to differentiate it from group D streptococci? PYR
The 2 most common kinds of infection caused by enterococci are ? 1. UTI 2. bacteremia
What sort of agar is used to culture enterococci? Trypticase soy or brain-heart infusion agar with sheep RBCs.
Enterococci grow best at what temp? 35C
Enterococcus faecalis is identified by its ability to grow in ? tellerite
Enterococci are resistant to many antimicrobial agents including glycopeptides such as __ and __. vancomycin and teicoplanin
Which classification of streptococci produce pus? pyogenic
Which classification of streptococci are often found in dairy products? lactococci
Which classification of streptococci are part of the normal biota of the human intestine? enterococci
Which classification of streptococci are normal biota of the upper respiratory tract? viridans
Which classification of streptococci are nonhemolytic and are Lancefield group N? lactococci
Bacitracin is useful for presumptive identification of __, which is susceptible to bacitracin. S. pyogenes
S. agalactiae is (resistant or susceptible?) to bacitracin. resistant
S. agalactiae has the enzyme __ which is useful in identifying it using the hippurate test. hippurate hydrolase
The only species of streptococcus that is PYR positive is ? (Enterococcus is also PYR positive.) S. pyogenes
A 9-year old boy has a sore throat and fever. His tonsils and pharynx are swollen. After 24 hours of incubation on SBA, colonies with beta-hemolysis grew. Name 3 tests that could be performed to ID the culprit. 1. bacitracin (culture is sensitive) 2. SXT susceptibility (culture is resistant) 3. immunoassay for group A antigen (Infection is S. pyogenes)
A beta-hemolytic, catalase negative, gram positive coccus is resistant to bacitracn and sulfamethoxazole. What is the presumptive ID? Group B streptococci
The CAMP test is based on enhanced hemolysis between CAMP factor and B-lysin from ? Staph. aureus
A nonhemolytic, catalase-negative, gram-positive coccus is PYR-positive. Would the isolate be: A) bile esculin positive B) salt tolerant C) bile soluble D) both A and B. A and B (bile esculin positive and salt tolerant)
The optichin test is most valuable in the ID of what? a-streptococci
What antimicrobial agent is most commonly used to treat infection of S. pyogenes? penicillin, though erythromycin can be used if patient allergic
Strep. pyogenes have been associated with what invasive infection? necrotizing fasciitis (there are other infections, but they are not invasive enough to count as the correct answer)
What species of strep is the most common cause of community-acquired pneumonia? S. pneumoniae/pneumococcus (duh)
What's the clinical significance of group B strep isolated from a vaginal culture of a pregnant woman? Neonates can acquire the infection in utero or during delivery.
How would you recover nutritionally variant streptococci from samples such as blood? They (Granulicatella and Abiotrophia) need pyridoxl. This can be combined with a blood culture. They can also grow around small pinpoint colonies of Staph. aureus which secretes some pyridoxal.
Enterobacteriaceae are gram-negative rods that ferment __, reduce nitrate to __, and are oxidase negative. ferment glucose, reduce nitrate to nitrite
The VP test detects which end product of glucose fermentation? acetoin or carbinol
Staph. capitis can be found on the ? scalp, forehead, and neck
Staph. auricularis can be found in the ? external auditory canal
Staph. intermedius isn't found on humans, but is found on ? canines
Staph. delphini can be found on what aquatic lifeform? dolphins
Staph. felis can be found on what household pet? cats
Staph. hominis can be found on ? humans
These 3 kinds of staph are found most often on humans. Staph. aureus, which is found on __, staph. epidermidis which is found on the __, and staph. saprophyiticus which is found in the __ area. aureus = mucous membranes, epidermidis = skin, saprophyticus = urino genital area
The only kind of staph that produces coagulase is ? staph. aureus
Streptococcaea are facultative ? anaerobes
Staph form in __ (shape) while strep form in __ (shape). staph form in clusters, strep in chains
Strep only spreads from the ? ends of the cells
Strep. pneumoniae, agalactiae and pyogenes are always considered ? pathogenic
Partial hemolysis with a green or grey area in the zone is called ? alpha
Total hemolysis with a clear or yellow zone is called ? beta
Does strep. pyogenes have a capsule? no
Strep. pyogenes is bacitracin __ and PYR __. bacitracin sensitive and PYR positive
Erythrogenic toxins of Strep. pyogenes causes ? scarlet fever
Streptolysin O and S of Strep. pyogenes does what? lyses RBCs
Streptokinase of Strep. pyogenes breaks down ? clots
Hyaluronidase of Strep. pyogenes is a spreading ? factor
TSLS is caused by toxins from S. pyogenes. It stands for ? toxic shock-like syndrome
Scarlet fever, as caused by Strep. pyogenes, causes redness on the face and what to appear on the tongue? dots
What are the 3 B's of group B streptococcus agalactiae? boys, boinking, babies
Besides pneumonia, Strep. pneumoniae causes what 3 things? 1. conjuctivitis 2. otitis media ear 3. Meningitis
The capsule of pneumoniae appear to be __ under a microscope. halos
Colonies in the __ quadrant of a BAP are usually the problem. 4th (and maybe 3rd)
Nuchal rigidity is the classic sign of ? meningitis
Viridans cause what 3 kinds of infections? 1. dental 2. endocarditis 3. bacteremia
Two viridans strep encountered frequently are ? 1.Strep. gallolyticus 2. Strep. mitis
Strep. pyogenes is in Lancefield group ? A
Strep. agalactiae is in Lancefield group ? B
Ent. faecalis is in Lancefield group ? D
Ent. faecium is in Lancefield group ? D
Strep. dysgalactiae, Strep. equi, are all in Lancfield group ? C
Strep. bovis is in Lancefield group ? D
Which streptococci are in hemolysis group beta? 1. S. pyogenes 2. S. agalactiae 3. S. dysgalactiae 4. S. equi
Which streptococci are in hemolysis group alpha? S. pneumoniae
Which streptococci are hemolysis groups alpha and gamma (no hemolysis)? S. bovis
Enterococcus are in which hemolysis groups? alpha, beta, gamma
What 5 features differentiate Staph. aureus from other species of staph? 1. coag negative 2. Mannitol fermentation 3. beta-hemolytic 4. protein A 5. exotoxins
Where is protein A found? In the cell walls of Staph. aureus
Name 3 important virulence factors possessed by Staph. aureus? 1. protein A 2. teichoic acid 3. polysaccharide capsule
Name the 3 most important exotoxins of Staph. aureus? 1. enterotoxin 2. TSST 3. exfoliative toxin
Which toxin is associated with watery nonbloody diarrhea, vomiting? enterotoxin (food poisoning)
How long does food poisoning by Staph. enterotoxin last? about 2 hours
Which food are associated with Staph. aureus enterotoxin/food poisioning? stuff with mayo
Which Staph. aureus toxins act as superantigens? enterotoxin and TSST
Describe an impetigo lesion. bullae and honey crusted
Impetigo is seen mostly in ? children
How are streptococci classified? by Lancefield group
Strep. pyogenes and agilactiae are both resistant to ? bacitracin
Which type of strep makes M protein? Strep. pyogenes
What toxins are associated with Strep. pyogenes? 1. erthogenic toxin 2. exotoxins A and B 3. streptolysin O and S
Created by: IsaacJ