Micro Review

Which of the following are the third and fourth most com- mon gram-negative bacilli found in clinical specimens? a. Pseudomonas spp. and Acinetobacter spp .b. Acinetobacter spp. and S. maltophilia c. B. parapertussis and S. maltophilia d. B. parapertussis and Pseudomonas spp.

.b. Acinetobacter spp. and S. maltophilia

Pregnant women and immunocompromised patients should avoid eating which of the following foods to pre- vent Listeria infection? a. Feta cheese b. Peanuts c. Pickles d. Ice cream

A

Removal of resistant bacterial spores can be accomplished using all of the following methods except: a. Moist heat at 121°C at 15 psi b. Incineration c. Moist heat at 132°C for 1 hour d. Dry heat at 180°C for 3 hours

A

The laboratory received a stool culture from a patient experiencing severe abdominal cramps and bloody diarrhea. The sample should be minimally processed using: a. BSL-1 safety practices b. BSL-2 safety practices c. BSL-3 safety practices d. Insufficient information is available to determine the correct answer.

B. BSL 2

A patient presents with a urinary tract infection. After 24 hours of incubation, the urine culture grows a non- lactose fermenter on MacConkey agar, colorless colo- nies on HE, indole-positive organism. The isolate is most likely: a. Citrobacter spp. b. Escherichia spp. c. Klebsiella spp. d. Proteus spp.

a. Citrobacter spp.

Which factor contributes to the pathogenicity of P.aeru- ginosa by inhibiting protein synthesis? a. Exotoxin A b. Pyoverdin c. Alginate d. Exoenzyme S

a. Exotoxin A

Which of the following organisms has multiple colonial morphologies and may have alpha-hemolytic colonies resembling streptococci? a. Lactobacillus spp. b. Gardnerella spp. c. Arcanobacterium spp. d. Bifidobacterium spp.

a. Lactobacillus spp.

Which actinomycete is partially acid-fast, has extensive aerial hyphae, and is lysozyme resistant? a. Nocardia sp. b. Rhodococcus sp. c. Gordonia sp. d. Tsukamurella sp.

a. Nocardia sp.

What is the antibiotic of choice for beta-hemolytic Streptococcus? a. Penicillin b. Tetracycline c. Bacitracin d. Vancomycin

a. Penicillin

Optochin sensitivity is used to differentiate: a. S.pneumoniae from other alpha-hemolytic streptococci b. S. pyogenes from S. pneumoniae c. S. agalactiae from S. pyogenes d. Enterococci from non-group D enterococci

a. S.pneumoniae from other alpha-hemolytic streptococci

Initial clues of the presence of this group of bacteria (sphingomonas) for clinical laboratorians are: a. They produce yellow pigment, do not grow on MacConkey agar, and oxidize glucose. b. They produce no pigment, do not grow in thioglycollate broth, and oxidize glucose. c. They produce tan/buff pigment, do not grow on blood agar, and oxidize xylose. d. They produce yellow pigment, do not grow on blood agar, and ferment glucose.

a. They produce yellow pigment, do not grow on MacConkey agar, and oxidize glucose.

A suspected isolate of Vibrio spp. is isolated from a young child with diarrhea. The organism is identified as a curved, gram-negative rod, oxidase and lactose positive, sucrose negative, that produces yellow colonies on TCBS and is NaCl tolerant. This organism is most likely: a. V. mimicus b. V. furnissii c. V. cholerae d. V. fluvialis

a. V. mimicus

If the Gram stain morphology or colonial morphology is suggestive of a possible actinomycete, which test should immediately follow? a. Ziehl-Neelsen (Acid-fast) b. Modified acid-fast c. Urea hydrolysis d. Nitrate reduction

a. Ziehl-Neelsen (Acid-fast)

A short-lived infection that manifests with a short incu- bation period and serious illness is considered to be

acute

Microorganisms that live in or on the human body without causing damage include :a. Colonizers b. Normal flora c. Microbiota d. Human microbiome e. All of the above

all of the above

bacterial cells genetically evolve by: Recombination with plasmids, transposons, and other bacterial chromosomes Mutation and recombination Use of the mechanisms of transduction, transformation, and conjugation All of the above

all of the above

What bacteria cause neonatal sepsis in 1- to 5-day-old infants? a. S. pyogenes b. S. agalactiae c. Enterococcus spp. d. Viridans streptococci

b S. agalactiae

This strict aerobic organism is commonly associated with urinary tract infection and is catalase-positive, nitrate- negative, and rapidly urease positive. a. C. jeikeium b. C. urealyticum c. R. equi d. D. hominis

b. C. urealyticum

Enterobacteriaceae are typically gram negative and: a. Non-glucose fermenters b. Capable of reducing nitrates to nitrites c. Catalase negatived. Oxidase positive

b. Capable of reducing nitrates to nitrites

Infection with which organism is associated with a high mortality rate in neonates? a. S. multivorum b. E. meningoseptica c. M. odoratus d. Chryseobacterium spp.

b. E. meningoseptica

Which organism is commonly considered an extrain- testinal pathogen? a. E. coli b. E. tarda c. P. shigelloides d. H. alvei e. K. oxytoca

b. E. tarda

Which E. coli produces a heat-labile (LT) enterotoxin and a heat-stable enterotoxin? a. UPEC b. ETEC c. MNEC d. EAEC

b. ETEC

Which of the following is the only catalase-negative, gram-positive, non-spore-forming rod that produces H S on TSI? 2 a. Gardnerella spp. b. Erysipelothrix spp. c. Lactobacillus spp. d. Arcanobacterium spp.

b. Erysipelothrix spp.

The D-zone susceptibility test is used to test inducible resistance on S. aureus strains demonstrating an initial antibiotic susceptibility profile of: a. Erythromycin sensitive, clindamycin sensitive b. Erythromycin resistant, clindamycin sensitive c. Erythromycin resistant, clindamycin resistant d. Erythromycin sensitive, clindamycin resistant

b. Erythromycin resistant, clindamycin sensitive

Which organism produces the CAMP factor enhancing beta-hemolysis in the presence of the S. aureus beta-lysin? a. Group A streptococci b. Group B streptococci c. Group C streptococci d. Group D streptococci

b. Group B streptococci

Which two tests can be used to differentiate C. diphtheriae from other corynebacteria? a. Halo on Tinsdale and positive nitrate b. Halo on Tinsdale and positive urea c. Black on Tinsdale and positive esculin d. Black on Tinsdale and positive nitrate

b. Halo on Tinsdale and positive urea

A reliable identification scheme for P. aeruginosa shows all of the following except: a. Oxidase positive b. No growth at 37°C c. Production of bluish-green pigment on Mueller- Hinton agar d. Triple sugar iron slant with an alkaline/no change reaction

b. No growth at 37°C

Sputum specimen inoculated on 5% sheep blood agar reveals alpha-hemolytic grayish colonies that are very mucoid. What test should be set up next? a. PYR b. Optochin c. Bacitracin d. CAMP

b. Optochin

Which of the following culture characteristics alert the microbiologist to a possible infection resulting from E. corrodens? a. Rapid growth on 5% sheep blood, chocolate, and MacConkey agar b. Pitting of the agar and a characteristic chlorine bleach smell c. Growth with alpha-hemolysis on 5% sheep blood agar and no growth on MacConkey agar d. Limited growth on 5% sheep blood, chocolate, and MacConkey agar, but improved growth using BYCE media

b. Pitting of the agar and a characteristic chlorine bleach smell

Which organism grows better under cooler temperatures (25°C) than in ambient air? a. Pseudomonas alcaligenes b. Psychrobacter spp. c. Comamonas spp. d. Cupriavidus pauculus

b. Psychrobacter spp

A clinical isolates test demonstrated the following results: catalase-positive, gram-positive cocci, nonhemolytic on blood agar plate, coagulase-negative, novobiocin resistant, PYR negative, and glucosidase-positive. The organism is most likely: a. S. cohnii b. S. saprophyticus c. S. xylosusd. S. epidermidis

b. S. saprophyticus

This nonfermentative gram negative rod is capable of H2S production: a. Alcaligenes xylosoxidans b. Shewanella algae c. Ochrobactrum anthropi d. Paracoccus yeei

b. Shewanella algae

The bacteria Weeksella and Bergeyella are biochemically similar. Which of the following test results is the correct result to differentiate the organisms? a. Weeksella is urease positive; Bergeyella is urease negative. b. Weeksella is urease negative; Bergeyella is urease positive. c. Weeksella is indole positive; Bergeyella is indole negative. d. Weeksella is indole negative; Bergeyella is indole positive.

b. Weeksella is urease negative; Bergeyella is urease positive.

Inhalation or pulmonary anthrax is also known as: a. Black eschar b. Woolsorters' disease c. Legionnaires' disease d. Plague

b. Woolsorters' disease

A stool specimen is submitted for culture. The results are: beta-hemolytic on blood agar, NLF on MacConkey, oxi- dase positive, bull's-eye appearance on CIN agar. This organism is most likely: a. A. hydrophilia b. Y. enterocolitica c. C. violaceum d. G. hollisae

b. Y. enterocolitica

All of the following organisms are considered normal intestinal microbiota except: a. C. freundii b. Y. enterocolitica c. E. coli d. E. aerogenes

b. Y. enterocolitica

An infection acquired from working with an animal reservoir is: a. Acquired from a vehicle b. Transmitted by a vector c. A zoonotic infection d. An example of indirect transmission

c. A zoonotic infection

Which factor contributes to the formation of biofilms by P. aeruginosa? a. Exotoxin A b. Pyoverdin c. Alginate d. Exoenzyme S

c. Alginate

Nonspecific immunity includes all of the following except: a. Inflammation b. Phagocytosis by neutrophils c. B-cell activation to produce antibodies d. Resident normal microbiota

c. B-cell activation to produce antibodies

No mode of transmission has been identified for which organism? a. A. denitrificans b. B. pertussis c. B. holmesii d. B. bronchiseptica

c. B. holmesii

A large, aerobic, beta-hemolytic, gram-positive rod is isolated from an eye culture. Subsequent testing reveals it is motile and produces a wide zone on egg yolk agar. The most likely identification of this organism is: a. Bacillus anthracis b. Escherichia coli c. Bacillus cereus d. Clostridium perfringens

c. Bacillus cereus

A large, aerobic, gram-positive, spore-forming rod is isolated from a blood culture. It can be further confirmed as B. anthracis if it is: a. Hemolytic and motile b. Hemolytic and nonmotile c. Nonhemolytic and motile d. Nonhemolytic and nonmotile

d. Nonhemolytic and nonmotile

The most common cause of hemolytic uremic syn- drome is: a. EPEC b. EAEC c. O157:NM d. O157:H7

d. O157:H7

Which of the following is the key pathogen that infects the lungs of patients with cystic fibrosis? a. B. cepacia b. B. pseudomallei c. P. fluorescens d. P. aeruginosa

d. P. aeruginosa

A 24-hour growth on a urine culture from a 20-year-old woman demonstrates grayish white beta-hemolytic colonies, which are catalase negative. What would be the next step for the microbiologist? a. Report the organism as S. pyogenes. b. Report the organism as S. aureus. c. Perform a PYR test. d. Perform a CAMP test and hippurate hydrolysis.

d. Perform a CAMP test and hippurate hydrolysis.

When streaking a throat culture on 5% sheep blood agar, stabbing the agar plate provides enhanced detection for: a. Bile solubility b. Bile esculin hydrolysis c. DNase activity d. Streptolysin O e. Streptolysin S

d. Streptolysin O

Identification approaches useful for speciation of Sphingomonas are: a. H2S production b. Citrate utilization c. DNase production d. a and c e. a, b, and c

e. a, b, and c

The virulence factor associated with B. cereus is: Edema toxin Lethal toxin Protective antigen Enterotoxin

enterotoxin

Which of the following organisms are PYR positive? a. Group A Streptococcus b. Group B Streptococcus c. S. urinalis d. Enterococcus spp. e. a and c only f. a, c, and d

f. a, c, and d

inanimate source of infection

fomite

insect that carries an infectious agent

fomite

The process consisting of a series of methods designed to provide the microbiologist with relevant and useful clinical information about a microorganism is:

identification

A microorganism that colonizes the skin but is capable of causing infection under the appropriate conditions is referred to as:

opportunistic pathogen

Prokaryotic chromosomes:

single copy dsDNA

The most specific and exclusive taxon used in the classifi- cation of microorganisms is:

species

characteristic of a disease- causing organism

virulence factor

The most appropriate therapy for inhalation anthrax is: a. Ciprofloxacin b. Tetracycline c. Vancomycin d. Erythromycin

a. Ciprofloxacin

All of the following are involved in humoral immunity except: a. Cytotoxic T cells b. Complement proteins c. Plasma cells d. Glycoproteins

A. cytotoxic t cells

All of the following can be used to detect toxin from C. diphtheriae except: a. Guinea pig lethality test b. Elek test c. ModifiedTinsdale d. PCR

C

All of the following factors affect the outcome when using a disinfectant except: a. Using water from a soft water system b. Disinfecting a surface that contains large pores c. The type of cloth used to wipe the surface d. Temperature and pH

C

In a chemical hygiene plan, the MSDS must include: a. The facility's name b. The laboratory director's credentials c. The substance's stability and reactivity d. The purchase date

C

Means of exposure to agents in the laboratory include all of the following except: a. Percutaneous inoculation b. Inhalation c. Drinking water d. Placing objects in the mouth

C

The periplasmic space is required for:

Collection and enzymatic degradation of nutrients in gram-negative bacteria

A blood culture isolate grew as a large, white, nonhemo- lytic colony on 5% sheep blood agar and was coagulase negative (slide method). The microbiologist should: Report as coagulase-negative staphylococci, probable contaminate Follow up with an oxidase and bacitracin test before reporting Complete a tube coagulase test Repeat the slide coagulase test with new controls

Complete a tube coagulase test

An engineering control includes: a. Positive air pressure capable of removing all hazard- ous contaminants b. Gloves, laboratory coats, and face shields c. Safety caps provided on tubes d. The use of biologic safety cabinets for sample processing

D

Most laboratories use which type of fire extinguisher? a. TypeA b.TypeB c. TypeC d. Combination ABC

D

Biofilm formation within a host results in:

Inability of the immune system to remove the pathogen

Humoral immunity: Is activated for all infectious agents Is specific for any organism Is specifically targeted to an antigen Provides a broad immune response to any microor- ganism

Is specifically targeted to an antigen

A sign is different from a symptom in all of the following ways except: It provides measurable data. It is believed to be associated with the etiology of the disease. It is clearly visible. It includes the temperature, respiratory rate, and pulse.

It provides measurable data. It is believed to be associated with the etiology of the disease.

Which of the following nonfermentative gram-negative bacilli are most commonly associated with clinical infections? Ochrobactrum spp., Shewanella algae Paracoccus yeei, Shewanella putrefaciens Ochrobactrum spp., Rhizobium radiobacter Rhizobium radiobacter, Paracoccus yeei, Shewanella algae

Ochrobactrum spp., Rhizobium radiobacter

All of the following are true of most Pseudomonas and Burkholderia spp. except: Nitrate negative Oxidase positive Grows on MacConkey agar Oxidizes glucose

Oxidizes glucose

Disinfection may be defined as a process that:

Removes pathogenic organisms but not spores

Rheumatic fever is a poststreptococcal sequelae typically associated with: Postpartum infections associated with group B streptococci Skin infections and pyodermas associated with group A streptococci Pharyngitis associated with group A streptococci Pneumonia associated with S. pneumoniae

Skin infections and pyodermas associated with group A streptococci

Classification and naming of organisms is useful in diag- nostic microbiology for all of the following except: Providing standardized groupings for identification Standardized groupings are always genotypically similar at .98% Standardized groupings share similar phenotypic traits The ability of organisms within a standard group may be identified using similar methods

Standardized groupings are always genotypically similar at .98%

Pasteurization is used to disinfect food products for all of the following reasons except: Topreventthekillingofflavor-addingmicroorganisms To prevent the destruction of essential vitamins and minerals in the food To completely sterilize food from contaminating organisms. To remove food pathogens

To completely sterilize food from contaminating organisms.

All of the following media used for the cultivation of Micrococcaceae are selective except: a. 5% sheep blood agar b. Phenylethyl alcohol agar c. Mannitol salt agar d. Colistin nalidixic acid agar

a. 5% sheep blood agar

Which of the following is considered an indirect mode of transmission? a. A cut with a dirty knife b. Ingesting contaminated potato salad c. Inhaling a droplet containing a bacterium d. Drinking water from a contaminated source

a. A cut with a dirty knife

Which organisms are plump coccobacilli that may resist decolorization and may be mistaken for Neisseria spp.? a. Acinetobacter spp. b. Bordetella spp. c. Stenotrophomonas sp. d. Burkholderia sp.

a. Acinetobacter spp.

Incubation of which organism at 25°C produces a characteristic yellow pigment? a. C. sakazakii b. P. shigelloides c. E. aerogenes d. H. alvei

a. C. sakazakii

A gram-negative, slightly curved, long bacilli is isolated from a female with respiratory symptoms that include dyspnea and cough. She recently was diagnosed with asthma and had been prescribed breathing treatments, which she administered at home using a humidified in- haler. What type of specimen should be collected and what media should be used to isolate the organism? a. Blood and sputum; MacConkey and blood agar b.Sputum; blood and chocolate agar c. Blood and sputum; blood culture broth, chocolate and blood agar d. Blood; blood culture broth

c. Blood and sputum; blood culture broth, chocolate and blood agar

Which organism is able to hydrolyze esculin and is a serious nosocomial pathogen? a. S. bovis b. S. mitis c. E. faecalis d. S. pneumoniae

c. E. faecalis

Which of the following species of Moraxella is able to liquefy serum, causing depressions in the surface of Loeffler's serum agar slants? a. M. nonliquefaciens b. M. osloensis c. M. lacunata d. M. canis

c. M. lacunata

Which of the following has a Gram stain morphology that resembles safety pins? a. B. diminuta b. B. mallei c. P. pseudomallei d. Ralstonia

c. P. pseudomallei

A patient presents to the physician with pain and frequency of urination. The urine culture reveals a non-lactose fer- menting, gram-negative rod with characteristic swarming on blood agar. The biochemical test that would specifically distinguish this organism from other Enterobacteriaceae is: a. Lactose fermentation b. Oxidase c. Phenylalanine deaminase and H2S d. Triple sugar iron agar

c. Phenylalanine deaminase and H2S

A patient presents with diarrhea after spending 2 weeks in Haiti after the country's devastation by an earthquake. A stool specimen is collected and inoculated to enrich- ment broth before subculturing to TCBS. After 48 hours of incubation on TCBS, no growth is identified on the media. What should the laboratory scientist do next? a. Request a new specimen. b. Run quality control organisms to check the integrity of the TCBS media. c. Report the culture as no growth with a comment that indicates the organism may be viable but noncultur- able, and the result does not rule out the presence of an infection. d. Report all cultures as no growth.

c. Report the culture as no growth with a comment that indicates the organism may be viable but noncultur- able, and the result does not rule out the presence of an infection.

Of all the bacteria discussed in this chapter, which one has been most highly implicated in disease? a. A. facilis b. S. mizutaii c. S. paucimobilis d. CDC group IIc

c. S. paucimobilis

Necrotizing fasciitis is a serious infection associated with: a. S. agalactiae b. S. mitis c. S. pyogenes d. S. epidermidis

c. S. pyogenes

Which organism has large, smooth, glistening colonies with a lavender pigment and smells like ammonia? a. Acinetobacter baumannii b. Pseudomonas luteola c. Stenotrophomonas maltophilia d. None of the above

c. Stenotrophomonas maltophilia

When disinfecting a contaminated surface, which of the following would provide the most efficient decon- tamination? a. 100% bleach for 10 minutes b. 80% bleach for 10 minutes c. 70% ethyl alcohol for 8 minutes d. 10% bleach for 5 minutes

d. 10% bleach for 5 minutes

A presumptive identification of G. vaginalis is sufficient for genital isolates, based on which diagnostic test? a. Beta-hemolytic HBT agar b. Negative oxidase c. Negative catalase d. All of the above

d. All of the above

Bacterial endotoxins are: a. All the same b. Part of the gram-negative cell wall c. Capable of causing a systemic shock response d. All of the above

d. All of the above

Which of the following patients are at higher risk of Acinetobacter infection? a. Patients in burn care units b. Patients in intensive care units c. Patients who have received multiple antibiotics d. All of the above

d. All of the above

Which organisms may stain partially acid-fast when stained with a modified acid-fast stain? a. Gordonia sp. b. Rhodococcus sp. c. Nocardia sp. d. All of the above

d. All of the above

Which organism is occasionally found in the respiratory tract of patients with cystic fibrosis? a. S. maltophilia b. Bordetella holmesii c. Bordetella parapertussis d. Burkholderia gladioli

d. Burkholderia gladioli

From which of the following infections is E. corrodens most often isolated? a. Urinary tract infections b. Sexually transmitted infections c. Middle ear infections d. Human bite wound infections

d. Human bite wound infections

A patient presents with diarrhea and abdominal cramp- ing. The organism isolated from the stool culture is identified as S. dysenteriae (group A). The TSI reaction would have indicated: a. K/K b. K/NC H2S + c. A/A d. K/A

d. K/A

Which organism exhibits end-over-end tumbling motility when incubated in nutrient broth at room temperature for 1 to 2 hours? a. C. diphtheriae b. C. jeikeium c. Arthrobacter sp. d. L. monocytogenes

d. L. monocytogenes

A female presents to the emergency department com- plaining of frequency and burning on urination. A urine sample reveals a fruity smelling, gram-negative rod that is oxidase, catalase, and urease positive and indole negative. The organism is most likely: a. S. spiritivorum b. E. coli c. P. aeruginosa d. M. odoratus

d. M. odoratus

Which one of the following organisms grows best at an incubation temperature of 25°C, instead of 35°C to 37°C? a. Bergeyella b. Weeksella c. E. corrodens d. Methylobacterium

d. Methylobacterium

Infection caused by non-acid-fast aerobic actinomycetes is usually chronic, granulomatous lesions of the skin referred to as: a. Mycelium b. Necrosis c. Impetigo d. Mycetoma

d. Mycetoma