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Micro1 Strep & Staph
Microbiology 1 Staph and Strep test - DelTech Owens Campus
| Question | Answer |
|---|---|
| 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
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