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102 Cards in this Set
- Front
- Back
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What are some characteristics of S. aureus?
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Positive catalase test Positive coagulase test |
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What test can be used to differentiate b/w a coag-neg staphylococcus species & a micrococcus species?
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Furazolidone (100ug/disk) susceptibility |
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Pustule drainage is plated onto primary media. After 18 hrs incubation, the SBA plate reveals a predominance of beta-hemolytic, white, porcelain-like colonies. Gram stain shows GPC. Catalase-positive. What is the best test for additional identification of the isolate?
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Coagulase |
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A 43-yr-old female patient complains of a very sore throat. The throat swab that is submitted for routine culture grows a variety of diphtheroids: alpha, beta, & gamma streptococci; staphylococci; & Neisseria. What is the next step? |
Identify the beta-hemolytic streptococcus species |
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A nasopharyngeal culture grows a predominance of a beta-hemolytic colony-type on SBA at 18 hrs. The isolate is susceptible to a 0.04 unit of bacitracin. The most likely ID is a beta-hemolytic streptococcus: |
Group A |
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What are some characteristics of Streptococcus pneumoniae? |
Bile-solubility-positive Gram-positive, oval-shaped cocci in pairs |
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Neisseria species can be identified and differentiated by...
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Carbohydrate utilization |
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A small gram-positive rod that causes neonatal meningitis and septicemia is... |
Listeria monocytogenes |
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The X & V factors required for growth of Haemophilus influenzae are contained in... |
Chocolate agar
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On an SBA plate, Haemophilus influenzae satellites around colonies of... |
Staphylococcus aureus |
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The specimen of choice for the isolation of Bordetella pertussis from a suspected case of whopping cough is... |
Nasopharyngeal swab |
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Family characteristics of the Enterobacteriaceae include... |
Fermentation of glucose
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PAD: Neg Urease: Neg H2S: Neg Lysine decarboxylase: Pos Ornithine decarboxylase: Pos Indole: Pos Citrate: Neg |
Escherichia coli |
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A mucoid, lactose-positive colony type on MAC that is indole-negative & citrate-positive, and non-motile is... |
Klebsiella pneumoniae |
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Escherichia, Klebsiella, & Proteus species are common flora of the... |
Gastrointestinal tract |
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PAD: Pos H2S: Pos Urease: Pos Lysine: Neg Ornithine: Pos Indole: Neg Citrate: Pos |
Proteus mirabilis |
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A gram-neg rod biochemically compatible with the genus Salmonella fails to agglutinate in the polyvalent somatic antisera for Salmonella serotyping. What is the next step in the definitive identification of this organism? |
Boil a saline suspension of the organism for 15 mins, cool, & retype in Salmonella polyvalent antiserum |
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A gram-negative rod is isolated from a patient with 2nd & 3rd degree burns. The isolate produces a bluish-green pigment and a characteristic fruity odor. Other characteristic observations are: Triple sugar iron: K/K Motility: Pos Oxidase: Pos Oxidative/fermentation glucose: Oxidative utilization only |
Pseudomonas |
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After 48 hours of incubation on anaerobic SBA, Clostridium perfringens appears as a... |
Large, flat colony with a double zone of hemolysis |
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Isolation of Campylobacter jejuni from a patient with gastroenteritis is optimized by... |
A microaerophilic environment |
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Ethylhydrocupreine hydrochloride (optochin) is a chemical used to differentiate... |
Streptococcus pneumonia from alpha-hemolytic streptococci |
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A lysine-iron agar (LIA) slant shows a red slant over a yellow butt. This indicates that the organism... |
Deaminates lysine |
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Simmon's citrate agar... |
Citrate is the only source of carbon in the medium Growth on the slant |
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In the N-acetyl-L-cysteine-alkali method of processing sputum specimens for mycobacterial culture, the N-acetyl-L-cysteine serves as a...
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Digestant |
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A sputum specimen is submitted to the lab accompanied by a request for an AFB culture. What are some standard protocols?
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Use of both liquid and solid media for setup of AFB culture Use of a laminar-flow biological safety cabinet for processing the specimen Use of a 4% sodium hydroxide solution for decontamination procedure |
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Routine sterilization of artificial culture media by autoclaving is recommended at...
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15 psi at 121 degrees Celsius for 15 mins |
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When acetone-alcohol is inadvertently omitted from the gram-stain procedure, streptococci and Neisseria will be stained, respectively... |
Purple and purple |
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The color of a nonacid-fast bacillus following the acid-alcohol step and before counterstaining in the acid-fast stain procedure is... |
Colorless
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MAC agar is used for the isolation of members of the family Enterobacteriaceae because the medium is... |
Inhibitory and differential |
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The reagent used to detect a positive phenylalanine-deaminase reaction is... |
Ferric chloride |
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To eliminate the antibacterial properties of blood and simultaneously introduce an adequate volume of blood for recovery of microorganisms from septicemia, the recommended blood-to-broth ratio in the blood-culture bottle is approximately... |
1:10 |
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Which specimen is acceptable for the evaluation of clinically important anaerobes?
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Peritoneal fluid |
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A urine is received in the laboratory for culture. If the specimen cannot be plated immediately, it should be held...
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In the refrigerator |
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Standardized testing conditions for the Kirby-Bauer agar-disk diffusion antimicrobial susceptibility test include what? |
Use of Mueller-Hinton media Standard inoculum size Incubation at 35 degrees Celsius |
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The pair of organisms that would provide a good positive and negative control for PEA (phenylethyl-alcohol) blood agar is...
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Enterococcus & E. coli |
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Which organisms will give the appropriate Pos & Neg reactions for QC of the Oxidase test? |
Pseudomonas aeruginosa & E. coli |
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A fungal colony grows rapidly on Sabouraud's dextrose agar as a white colony type with a dense production of aerial, blue-green spores. On lactophenol cotton blue prep, swollen-tipped conidiophores bear sterigmata and conidia in chains. What is the most likely ID of this isolate?
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Aspergillus |
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A saprobic yeast that inhabits airborne dust, skin, and mucosa grows rapidly and produces an orange-to-red color. This isolate most likely belongs to the genus...
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Rhodotorula |
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The function of 10% potassium hydroxide in the direct exam of skin, hair, and nail scrapings is to...
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Clear and dissolve debris |
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A potentially pathogenic yeast that is normal flora in the oropharyngeal cavity and may produce thrush is... |
Candida albicans |
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In an iodine preparation of feces, an amoebic cyst appears to have a single nucleus/ a large karyosome and chromatin bodies do not appear along the nuclear membrane. A large glycogen mass that stains reddish brown occupies the cytoplasm. What is the most probable identity of the cyst? |
Iodamoeba butschlii |
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The infective stage of this parasite consists of an egg with a thin hyaline shell, with one flattened side and, usually, a fully developed larva within. What is the parasite?
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Enterobius vermicularis |
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The direct iodine preparation is best used to detect protozoan...
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Cysts |
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Parasites that are detected by direct visualization in a pheripheral blood smear are...
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Plasmodium |
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Chlamydiae differ from viruses in that chlamydiae...
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Are true bacteria |
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A specimen for viral culture is collected on a Friday and must be held for processing until the next day. In general, the optimal temperature for holding this specimen is... |
4 degrees Celsius |
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A procedure that directly determines beta-lactamase production by a microorganism is based on detection of an... |
Increased acidity due to the release of penicilloic acid |
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In a broth-dilution method of antimicrobial susceptibility testing, the tube with the lowest concentration of antimicrobial in which there is no visible growth is the minimal...
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Inhibitory concentration |
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Giardia lamblia trophozoites, which are recovered from steatorrheic stool, will produce what?
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Malabsorption syndrome
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Aspergillus species
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Shows an erect condiophore that terminates in a vesicle on which phialides are borne. Species are differentiated by the conidial arrangement |
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Appearance: Yellow, cloudy Specific gravity: 1.025 pH: 8.0 Glucose: Neg Nitrite: Pos Protein: 1+ Blood: Neg Ketones: Neg Bilirubin: Neg Microscopic: no casts, 15-25 WBCs/hpf; many bacteria present Results indicate what? |
Significant urinary-tract infection that correlates to a probable original count of greater than 10 to the fifth CFU/ml should be suspected |
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This adult disease results from preformed neurotoxin that is ingested and causes the symptoms of neuromuscular flaccid paralysis. The agent that produces the toxin is...
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Clostridium botulinum |
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Two siblings arrive at the ER. Both had antecedent sore throats about 2-3 weeks earlier that grew beta-hemolytic streptococci; now they present with different clinical symptoms. The brother displays edema and hypertension, and RBC casts are seen in the urine. The sister complains of fever and joint pains and has carditis. The diseases that these siblings have are most likely... |
Glomerulonephritis & rheumatic fever |
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Purulent material is obtained from a carbuncle and submitted for bacterial culture. The direct smear reveals many GP & WBCs. The culture shows growth in the primary broth and on the SBA plate and no growth on the MAC plate. The colonies on the SBA plate are butyrous, white, and beta-hemolytic. The catalase test is positive and modified oxidase test is negative. Although the slide coagulase test is negative, the tube coagulase test is positive. The most probable ID of this isolate is... |
Staphylococcus aureus |
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What is a unique characteristic of Pseudomonas aeruginosa?
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Production of pyocyanin, a blue or blue-green pigment |
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On TCBS (thiosulfate-citrate-bile-salts-sucrose) agar, colonies of Vibrio cholerae appear... |
Yellow |
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A GN coccobacillary organism that is isolated fromm synovial fluid on Chocolate agar resembles either a Moraxella species or Neisseria gonorrhoeae. The single best test to distinguish between these organisms is... |
Glucose degradation |
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A lumbar puncture is performed on an 82 yr old woman who is receiving immunosuppressive therapy. The direct Gram's stain of the CSF reveals small GP rods & numerous WBCs. At 18 hrs, small translucent colonies with narrow zone of beta hemolysis grow on SBA. The isolate produces catalase. ID of this isolate could be made by demonstration of... |
Tumbling motility |
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In an overcrowded poverty-stricken central core of a US-Mexico border town, a 15 month old baby girl is admitted to the city hospital. Physical exam of this child reveals fever, repetitive coughing spells that make the child gasp for air, and a cyanotic appearance. Lab findings show lymphocytosis. The probable diagnosis is... |
Pertussis |
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Requires an atmosphere of 10% CO2 Urease-Pos in 1-2 hrs Grows in the presence of thionine dye but not in the presence of fuchsin. What is described here? |
Brucella abortus |
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A patient is admitted to the hospital with symptoms of appendicitis. A stool specimen for culture reveals a GN bacillus that is oxidase-neg, catalase-pos, urease-pos, and weakly fermentive. The slant of KIA (Kligler's iron agar) is orange-yellow but the TSI (triple sugar iron agar) shows yellow slant & yellow butt. These reactions suggest the possibility of... |
Yersinia enterocolitica |
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Both blood and urine cultures are positive of an oxidase-negative, gram-negative rod that is colorless on MAC. Biochemical reactions include the following: TSI: A/A, gas + H2S-Neg Phenylalanine deaminase: Neg H2S: Neg Indole: Neg Citrate: Pos Motility: Pos DNase: Pos Arabinose: Alkaline Lysine decarboxylase: Pos Ornithine decarboxylase: Pos The opportunistic pathogen that shows these reactions is... |
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The metabolism of glucose by the Klebsiella-Enterobacter-Serratia group is as follows: Glucose --> 2,3-butanediol + 2 CO2 + H2 The reaction in the basis for the... |
Voges-Proskauer test |
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A stool specimen is submitted for culture from a patient with gastroenteritis, nausea, and vomiting. A GN rod grows on TCBS agar as a large green colony type. Additional screening characteristics include: TSI: Alk/Acid H2S: Neg Oxidase: Pos Nutrient broth w/ 0% NaCl: NG Nutrient broth w/ 3% NaCl: Growth Catalase: Pos Nitrate: Pos Lysine: Pos The most probable presumptive ID of this isolate is... |
Vibrio parahaemolyticus
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O-F glucose (aerobic): Acid O-F glucose (anaerobic): Alk Oxidase: Neg TSI: Alk/No change Orthonitrophenyl galactoside (ONPG): Neg Lactose: Alk Maltose: Alk Mannitol: Alk Sucrose: Alk Xylose: Acid This isolate also produces acid from a 10% lactose agar slant. The ID of this isolate is... |
Acinetobacter baumannii |
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What results are consistent with the ID of Mycobacterium fortuitum?
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Nitrate reduction: Pos Growth on MAC Growth in 5% NaCl |
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An AFB (acid-fast bacillus) has been isolated from the sputum of a patient suspected to have a mycobacterial pulmonary disease. The organism is a slow-growing isolate that produces cream to tan colored when grown in the dark in the incubator and turns bright yellow upon exposure to light. What is the most likely ID of this organism?
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Mycobacterium kansasii |
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Nocardia species that cause nocardiosis often are...
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Partially acid-fast |
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A direct Gram's stain of a pelvic mass from a patient with an IUD shows numerous pus cells and branching, beaded GP rods. Heaped, lobate colonies grow anaerobically and develop a molar-tooth appearance after several days of incubation. The most probable identity is... |
Actinomyces israelii |
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Anaerobic SBA: 3+ GN rods Anaerobic laked-blood afar with kanamycin-vancomycin: 3+ GN rods The isolate fluoresces a brick-red color under long-wave UV exposure. If allowed to incubate several more days, the colonies would be visibly... |
Black-pigmented |
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Two organisms that are thought to act synergistically to produce an ulcerative infection of the gums, commonly called trench month, are... |
Fusiforms & treponemes
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A physician inquires about repeated sputum specimens, negative on routine bacterial culture, that are reported to contain only normal oropharyngeal flora on routine bacterial culture. The patient is a 67-yr old man who smokes 15-20 cigarettes a day and has persistent cough, malaise, and a fever of 102-105 degrees Farenheit. Empiric antimicrobial therapy has not been effective; the cough and fever persist. The most recent direct Gram's stain of sputum shows 3+ PMNs, mucus present, and rare epithelial cells. A likely etiologic agent is...
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Legionella pneumophila |
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What are some descriptions of Pasteurella multocida? |
No growth on MAC Non-hemolytic on SBA Oxidase-Pos |
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Which media has a high protein content and requires sterilization by inspissation? |
Lowenstein-Jensen egg |
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Descriptions of the ONPG (orthonitrophenyl galactoside) test...
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It is positive for organisms that produce both beta-galactosidase and galactoside permease It is positive for isolates that are capable of fermenting lactose but lack the permease |
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Bacteria that are glucose oxidizers in Hugh-Leifson (H-L) O-F medium produce an alkaline/no change reaction in KIA because...
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These organisms produce insufficient amounts of acid to be detected on KIA |
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Glucose: Acid Lactose: Acid Maltose: Acid Sucrose: Acid The most appropriate action to take is... |
Gram's stain and subculture the CTA sugars to check them for purity |
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Special handling or methods are NOT required when blood cultures are requested on a patient to recover any of which organism?
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Salmonella serotype typhi
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Safety precautions designed to minimize laboratory-acquired infections when working with Mycobacterium tuberculosis in a clinical laboratory would prevent spreading of these organisms by...
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Aerosol production |
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To check for positive and negative reactions, select the appropriate set of quality-control microorganisms for the following tests: Bile esculin hydrolysis Bacitracin susceptibility 6.5% NaCl tolerance Hippurate hydrolysis |
Streptococcus agalactiae enterococci |
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Blastomyces dermatitidis
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Coccidioides immitis |
@ room temperature, white to brown colonies with cottony aerial mycelia; microscopically, septate hyphae dissociate and fragment into barrel-shaped arthroconidia |
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Histoplasma capsulatum |
@ room temperature, silky-smooth, white to tan colonies; microscopically, echinate, tuberculated, spherical macroconidia |
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Sporothrix schenckii |
@ room temperature, smooth cream to white colonies that turn brown with age; microscopically, branched slender conidiophores with small conidia arranged in flowerettes or in a sleeve arrangement |
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Fusarium species have, on occasion, been associated with corneal ulcers, ulcerated skin conditions, and mycetoma. Typical macromorphologic and micromorphologic features are... |
Rapid growers that usually produce a lavender pigment and crescent-shaped, septate macroconidia |
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An 8 yr old child presents with tinea capitis, thought to be caused by Microsporum canis. Characteristics of this fungi include... |
Spindle-shaped, thick-walled macroconidia with an asymmetric terminal knob |
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Candida albicans
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Germ tube-Pos Chlamydoconidia producer |
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What is characteristic of Dientamoeba fragilis? |
No known cyst stage, trophozoite shaped like an amoeba |
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A thick film has been prepared from a patient suspected of having malaria. It is stained with Wright's stain. Inclusions seen in the patient's erythrocytes are described as blue disks with red nuclei. The infected erythrocytes are generally enlarged and some have granules of brownish pigment. Many of the erythrocytes appear to have more than 15 nuclear masses in a single cell. Identify the parasite described. |
Plasmodium vivax |
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The diagnostic stage of Strongyloids stercoralis infection is the... |
Larva |
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Trematodes that mature in the lung and produce eggs that appear in the sputum or stool are probably... |
Paragonimus westermani |
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A 15 yr old girl was admitted with severe headache and confusion. An exam of her spinal fluid revealed many small, motile amebae. The girl was visiting friends in GA and had been swimming and diving in a freshwater pond. The most likely genus and species of the organism is... |
Naegleria fowleri |
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The causative agent of Q fever is... |
Coxiella burnetii |
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Cerebrospinal fluid from a 24 yr old man reveals a high number of mononuclear cells and a negative routine culture for bacteria. Spinal fluid, glucose, and protein values are normal. In addition, the patient has vesicular genital lesions. The most likely etiologic agent is... |
Herpes simplex virus |
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A 20 yr old man with urethritis who had been treated with penicillin returns to the outpatient clinic the following week. A possible cause of this symptoms is Chlamydia trachomatis, which may be confirmed by... |
Demonstrating inclusion bodies in the cell culture |
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You suspect a yeast isolated from a urine sample of a 25 yr old female patient is Candida albicans. Which of the following is the test when positive that will presumptively identify your isolate? |
Germ tube test |
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A recently FDA-approved direct antigen test to detect Group A streptococcus in throat samples shows a 90% sensitivity and 98% specificity. In a population with an estimated prevalence of 5%, the calculated positive predictive value for this test is 70.3%. This means that... |
There is a 30% chance an individual may not have the disease |
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Falsely decreased zone diameters on a Kirby-Bauer agar disk-diffusion test would most likely result from...
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A 2 hr delay in placing the antimicrobial disks on the seeded plate |
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In interpreting a MIC (minimal inhibitory concentration) by macrobroth-dilution, you determine that the first test tube that shows visible turbidity has a final dilution factor of 1:32. Since twofold serial dilutions are made from the working stock of 0.256 mg/mL, the MIC for this isolate is... |
16 ug/mL |
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In a synergy study, when drug A, drug B, and drug A+B act singly and in combination on a single population of growing bacteria in vitro, the type of killing action signified is...
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Indifference |
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In the Kirby-Bauer agar-disk diffusion susceptibility test, a steady decrease in zone diameter of the methicillin disks obtained with the control organism Staphylococcus aureus, ATCC 25923, may be due to the fact that the... |
Methicillin disks were not stored frozen |
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Clue cells seen in a malodorous vaginal discharge are associated with a diagnosis of bacterial vaginosis; vaginal culture typically shows a predominance of... |
Gardnerella vaginalis |
