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AAB MT Microbiology 2023 215
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What term describes the morphology of organisms that vary in shape and size? - answer Pleomorphic Capsules are the basis of which test? - answer Serotyping A mucoid colony on blood agar medium indicates that which of the following characteristics may be present? - answer Organism has a capsule. What are dark staining granules called? - answer Metachromatic Which of the following organisms are non-motile? - answer Shigella and Klebsiella In the bacterial growth cycle, growth ceases because nutrients are exhausted or toxic metabolic products have accumulated in which phase? - answer Stationary phase Which of the following genera of bacteria form spores? - answer Bacillus and Clostridium What term is used to describe bacteria that grow in the absence of atmospheric oxygen and obtain oxygen from oxygen-containing compounds? - answer Anaerobes What is the temperature at which bacteria grow best known as? - answer Optimum On blood agar plates a small zone of alpha hemolysis surrounded by a zone of beta hemolysis after refrigeration is known as what type of hemolysis? - answer Alpha-prime hemolysis
What is the most effective method of sterilization? - answer Autoclaving Which of the following is used for quality control for the dry heat oven? - answer Bacillus subtilis Media that cannot be heated can be sterilized by what alternate method? - answer Filtration Which one of the following disinfectants is the most effective germicide against bacteria, spores, tubercle bacilli, fungi, and viruses? - answer Chlorine What is a term that describes a process or treatment that renders a medical device, instrument, or environmental surface safe to handle? - answer Decontamination What color do gram-positive bacteria stain? - answer Purple Acid-fast bacteria appear what color microscopically? - answer Red Acid-fast organisms in tissue are best stained by which of the following methods? - answer Kinyoun Which of the following should be used to remove antimicrobials before culturing? - answer Antimicrobial removal device Which statement concerning sodium polyanethol sulfonate (SPS) is NOT true? - answer Activates some antimicrobials What are some functions of sodium polyanethol sulfonate (SPS)? - answer Prevents blood from clotting, prevents phagocytosis, and neutralizes the bactericidal effect of human serum.
What is the preferred method of differentiating S. aureus from S. epidermidis? - answer Coagulase test A colony of nonhemolytic, catalase-positive, coagulase negative, GPC is most likely to be which organism? - answer Staphylococcus epidermidis When performing a bacitracin differentiation test for Group A beta-hemolytic streptococci, disks should be used that have how many units? - answer 0.02-0.04 unit Hippurate hydolysis is used to differentiate which organisms? - answer Group A streptococci from Group B streptococci If pneumococci are resistant to penicillin, then they should be tested for which of the following?
- answer Beta-lactamase production Beta-lactamases - answer Enzymes produced by some bacteria which provide resistance to beta-lactam antibiotics like penicillins, cephamycins, and carbapenems. Common Beta-lactamase positive organisms - answer S. epidermidis, P. aeruginosa, K. pneumoniae, and E. coli What is the most probably identity of a bile-esculin positive, beta-hemolytic streptococci that grows in 6.5% NaCl? - answer Enterococci The bile-esculin test is used to differentiate which two organisms? - answer Group D Streptococci and Enterococci An oxidase-positive, Gram-negative cocci from a throat culture might be which organism? - answer Neisseria
Oxidase test - answer A test used in microbiology to determine if a bacterium produces certain cytochrome c oxidases. The reagent is a dark-blue to maroon color when oxidized, and colorless when reduced. Oxidase-positive organisms - answer Neisseria, Moraxella, H. pylori, V. cholera, C. jejuni, Aeromonas, and L. pneumophila Oxidase-negative organisms - answer Enterobacteriaceae (Salmonella, E. coli, Y. pestis, Klebsiella, Shigella, Proteus, Enterobacter, Serratia, and Citrobacter) and Haemophilus A fastidious, oxidase-positive, Gram-negative cocci from a rectal swab might be presumptively identified as which organism? - answer Neisseria gonorrhoeae Gram-negative, coffee bean-shaped diplococci with adjacent sides flattened is descriptive of which of the following? - answer Neisseria Which of the following specimens may be inappropriate for culturing Neisseria gonorrhoeae? - answer Urine What best describes Thayer-Martin media? - answer Enriched chocolate agar What differentiates Thayer-Martin medium from modified Thayer-Martin medium? - answer Trimethoprim lactate What is the medium of choice for culturing gonococci and meningococci? - answer Modified Thayer-Martin media When performing the oxidase test, which of the following techniques CANNOT be used? - answer Use a nichrome loop to transfer the colony to the filter paper.
What is the purpose of potassium tellurite in tellurite medium? - answer Inhibits normal flora Potassium tellurite medium produces what color colonies of C. diphtheriae - answer Gray-black When culturing C. diphtheriae, which of the following media will enhance pleomorphism and granule production? - answer Loeffler serum agar The Elek test is for the detection of which toxin? - answer C. diphtheriae toxin Which of the following diphtheroids is normal flora in the throat? - answer Corynebacterium pseudodiphtheriticum How long does the morphological cycle of Rhodococcus equi from coccoid to rod form take? - answer 24 hours Which of the following is a Gram-positive to Gram-variable coccobacillus? - answer Listeria monocytogenes Refrigeration of the specimen for several months may enhance isolation of which organism? - answer Listeria monocytogenes Listeria monocytogenes produces a positive in which one of the following biochemical tests? - answer Catalase Listeria monocytogenes is negative for these biochemical tests? - answer Coagulase, beta- lactamase, and the lactose fermentation test. Which of the following will differentiate Listeria monocytogenes from Corynebacteria species? - answer Nonmotile and salicin negative
Spore-forming cells in bamboo pole arrangement are characteristic of which organism? - answer Bacillus anthracis Which aerobic, Gram-positive, sporulating rod can cause food poisoning? - answer Bacillus cereus Which one of the following will stain acid-fast bacilli? - answer Kinyoun stain What is the function of N-acetyl-L-cysteine-NaOH? - answer Liquefy mucus and control contaminants How should mycobacterial cultures be incubated? - answer In 5% CO Which of the following media is clear so that colonies of mycobacteria can be examined microscopically? - answer Middlebrook 7H What are some methods for identification of mycobateria? - answer Biochemical reactions, pigment production, and growth rate. NOT spore formation! What color is a negative enzymatic hydrolysis Tween 80 test? - answer Amber How is Mycobacterium tuberculosis best differentiated from Mycobacterium bovis? - answer Niacin and nitrate tests (M. bovis is nitrite and niacin negative) A slow-growing, unbranched, acid-fast bacilli that is nitrate negative and niacin negative is most likely which organism? - answer Mycobacterium bovis Which differential test for identifying the species of mycobacterium spits phenolphthalein from tripostassium phenolphthalein-sulfate within 2-3 days? - answer Arylsulfatase test
Which medium is preferred for the culture of Haemophilus species? - answer Enriched chocolate agar Cultures of Staphylococcus aureus supply which of the following to cultures of Haemophilus? - answer V factor Which organism causes whooping cough? - answer Bordatella pertussis What is the preferred method for the isolation of Bordatella pertussis? - answer Regan-Lowe medium Which of the following species of Bordatella are urease-positive and oxidase-positive? - answer B. parapertussis A Brucella isolate that does not produce H2S, does not require CO2, and is not inhibited by thionin or basic fuschin is probably which species of Brucella? - answer B. melitensis A relatively slow growing and fastidious Gram-negative rod that produces a characteristic brown pigment on Feeley-Gorman iron cysteine agar is most probably which organism? - answer Legionella pneumophila What is the best medium for the isolation of Legionella? - answer Buffered charcoal yeast extract agar Which Gram-negative, fastidious bacillus has been isolated from air-conditioning towers? - answer Legionella pneumophila Which atmospheric conditions are best for Campylobacter? - answer Obligate microaerophilic
A curved, Gram-negative rod that is nonfermentative, nitrite positive, and microaerophilic is probably which organism? - answer Campylobacter jejuni A motile, Gram-negative, slender, curved rod that is the cause of enteritis is best isolated on which agar? - answer Campylobacter blood agar What does the Campy gas mixture consist of? - answer 5% O2, 10% CO2, 85% N Which organism colonizes the human stomach and is associated with peptic ulcer disease? - answer Helicobacter pylori Clue cells may be found in infections with which organism? - answer Gardnerella vaginalis What kind of media extends the lag phase of normal flora and decreases the lag phase of pathogens? - answer Enrichment media Which type of selective media for Salmonella and Shigella uses bromthymol blue and acid fuschin as indicators? - answer Hektoen Enteric (HE) agar What is the hydrogen sulfide indicator in triple sugar iron agar? - answer Sodium thiosulfate IMViC is a series of which of the following tests? - answer Indole, methyl red, Voges-Proskauer, and citrate. Which tests for evidence of an enteric bacterium. What is the indicator in the methyl red test? - answer Methyl red Which pair of organisms can be used for quality control in the Voges-Proskauer test? - answer Enterobacter (positive) and Echerichia (negative)
Hydrogen sulfide production, other than in triple sugar iron agar, requires a source of metal and what other component in the test medium? - answer An organic source of sulfur All of the following organisms are nonmotile at 37 degrees C except which one? - answer Proteus vulgaris Gelatinase breaks down gelatin into which end products? - answer Amino acids What indicates a positive DNase result after 0.1 HCl is added to the plate? - answer Clearing around the colony What is the DNase test? - answer DNase agar is a differential medium that tests the ability of an organism to produce an exoenzyme, called deoxyribonuclease or DNase, that hydrolyzes DNA. DNase agar contains nutrients for the bacteria, DNA, and methyl green as an indicator. If the negative nitrate reduction test does not change color after the powdered zinc is added, how is it reported? - answer Positive -- No color after powdered zinc Negative -- Red after powdered zinc What is the purpose of the ONPG test? - answer Detects slow lactose fermenters What is the ONPG test? - answer Ortho-Nitrophenyl-β-galactoside (ONPG) is a colorimetric and spectrophotometric substrate for detection of beta-galactosidase activity. β-galactosidase is required for lactose utilization. Negative = no color; positive = yellow. Salmonella, Shigella, and Eschericia coli have what in common? - answer All are members of Enterobacteriaceae A GNR isolated from a urine culture has the following reactions: IMViC ++--
Motility Positive Urease Negative - answer Escherichia coli A GNR isolated from a stool culture has the following reactions: Urease Negative Phenylalanine deaminase Negative Lysine decarboxylase Negative Motility Negative Citrate Negative - answer Shigella dysenteriae A mucoid lactose fermenter was isolated from a sputum specimen on MacConkey agar with these reactions: Motility Negative Oxidase Negative Citrate Positive - answer Klebsiella pneumoniae A GNR was isolated from a blood culture with the following biochemical reactions: Urease Positive Phenylalanine deaminase Positive Citrate Positive Motility Positive - answer Proteus mirabilis Which of the following organisms is NOT oxidase positive? - answer NOT oxidase positive: Yersinia enterocolitica Oxidase positive: Aeromonas hydrophilia, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Rice water stools often contain a pure culture of which organism? - answer Vibrio cholerae
Which Clostridium produces a double zone of hemolysis around colonies on blood agar? - answer C. perfringens Which anaerobic, Gram-positive rod produces terminal "tennis racket" spores? - answer Clostridium tetani Which one of the following species of Clostridium causes antimicrobial-associated diarrhea? - answer C. difficile Which Gram-negative, anaerobic cocci produces a red fluorescence under ultraviolet light? - answer Viellonella Which one of the following best describes Peptococcus? - answer Anaerobic, Gram-positive cocci Why are mycoplasmas not considered true bacteria? - answer They have no cell wall. Which one of the following organisms forms colonies that are embedded in the agar giving a "fried egg" appearance? - answer Mycoplasma pneumoniae What is the best method for identification of Mycoplasma species? - answer Inhibition of growth by specific antisera What is the cause of primary atypical pneumonia? - answer Mycoplasma pneumoniae Which of the following have a bacterial type cell wall? - answer Chlamydias and Rickettsias Which of the following is a small, nonmotile, coccobacillus that grows in egg yolk sacs? - answer Rickettsia
How are ricketssial diseases transmitted? - answer Arthropod vectors Which of the following is not caused by Rickettsia? - answer Typhoid fever and Rickets Rickettsia causes - answer Typhus, Q fever, and scrub typhus Which organism causes pelvic inflammatory disease? - answer Chlamydia trachomatis What is the most common tick-borne disease in the US? - answer Lyme disease What is erythema chronicum migrans? - answer Sign of Lyme disease at the site of the tick bite. What are substances, produced by microorganisms, that in very small amounts inhibit other microorganisms? - answer Antibiotics All of the following are characteristics of broad-spectrum antibiotics EXCEPT which one? - answer Act against viral agents Bacteriostatic agents do which of the following? - answer Inhibit the growth of the organism What is the time it takes half a dose of antibiotic to disappear from the blood called? - answer Half-life Resistance to an antibiotic can be transferred from a resistant to a susceptible organism by which mechanism? - answer Extrachromosomal plasmid In the KB susceptibility test, what is the 0.5 McFarland standard used for? - answer To adjust the turbidity of the inoculum
Which test, when positive, can be used for the presumptive identification of Candida albicans? - answer Germ tube test Which statement is NOT true concerning the causative agents of dermatophytoses? - answer Trichophyton rubrum has club-shaped macroconidia Which of the following is found in the yeast phase of Sporothrix schenckii on culture medium at 37 degrees C? - answer Cigar-shaped yeast cells Which one of the following organisms has a wide, refractive capsule? - answer Cryptococcus neoformans What does the tissue phase of Histoplasma capsulatum characteristically show? - answer Tuberculate macroconidia What is the infective form of dimorphic fungi for laboratory workers? - answer Hyphal form Which intestinal flagellate trophozoite has a sucking disk, two nuclei, eight flagella, and an axostyle? - answer Giardia lamblia Which malarial species can be identified by the presence of crescent-shaped gametocytes in the peripheral blood? - answer Plasmodium falciparum Which of the following worms has an oral and ventral cup-shaped sucker in the adult stage? - answer Trematodes What is the common name for schistosomes? - answer Blood flukes
Which tapeworm could be acquired through the ingestion of medium-rare steak? - answer Taenia saginata Which tapeworm eggs have an operculum at one end and a small terminal knob at the other end? - answer Diphyllobothrium latum Which intestinal roundworm migrates to the perianal skin to deposit embryonated eggs? - answer Enterobius vermicularis Muscle biopsy is a diagnostic technique employed to detect which one of the following tissue roundworms? - answer Trichinella spiralis Cutaneous larva migrans or creeping eruption is caused by which organism? - answer Ancylostoma braziliense Which zoonoses can be caused by the ingestion of raw fish infected with larvae from sashimi? - answer Anisakiasis What color does the cytoplasm of protozoan cysts stain in the iodine wet stool preparation? - answer Yellow-brown All of the following are advantages to the sedimentation method EXCEPT for which one? - answer Separates protozoan cysts and helminth eggs What is a mature virus particle containing a nucleic acid core surrounded by a protein coat, with or without an envelope called? - answer Virion All of the following are consided potential viroterrorism agents EXCEPT which virus? - answer SARS-CoV virus
