Magen Ross
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Bacteriology Pre-test Microbiology

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Magen Ross
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Pre-Test Microbiology - Bacteriology

Pre-Test Microbiology - Bacteriology

Question 1 of 77

1

A patient with a peptic ulcer was admitted to the hospital and a gastric biopsy was performed. The tissue was cultured on a chocolate agar, incubated in a micraerophilic environment at 37 F for 5 to 7 days. At 5 days of incubation, colonies appeared on the plate and were curved, Gram-negative rods, oxidase-positive. The most likely identity of this organism is

Select one of the following:

  • Campylobacter jejuni

  • Vibrio parahaemolyticus

  • Haemophilus influezae

  • Helicobacter pylori

  • Campylobacter fetus

Explanation

Question 2 of 77

1

An experimental compound is discovered that prevents the activation of adenyl cyclase and the resulting increase in cyclic AMP. The toxic effects of which of the following

Select one of the following:

  • Vibrio cholerae

  • Corynebacterium diphtheriae

  • Pseudomonas

  • Listeria monocytogenes

  • Brucella

Explanation

Question 3 of 77

1

An inhibitor was designed to block a biologic function in H. influenzae. If the goal of the experiment was to reduce the virulence of H. influenzae, the most likely target would be

Select one of the following:

  • Exotoxin liberator

  • Endotoxin assembly

  • Flagella synthesis

  • Capsule formation

  • IgA protease synthesis

Explanation

Question 4 of 77

1

A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week.
Based on the information given, the most likely diagnosis is

Select one of the following:

  • Mycoplasma pneumonia

  • Pneumococcal pneumonia

  • Staphylococcal pneumonia

  • Influenza

  • Legionellosis

Explanation

Question 5 of 77

1

There are millions of cases of leprosy (Hansen’s disease) worldwide, but predominately in Asia and Africa. The clinical spectrum of Hansen’s disease is best characterized by

Select one of the following:

  • Immunologic anergy

  • Chronic pneumonitis

  • Peripheral neuritis

  • Bacilli in lesions that digest tissues

  • Erythematous lesions resembling concentric circles

Explanation

Question 6 of 77

1

At a church supper in Nova Scotia, the following meal was served: baked beans, ham, coleslaw, eclairs, and coffee. Of the 30 people who attended, 4 senior citizens became ill in 3 days; 1 eventually died. Two weeks after attending the church supper, a 19-year-old girl gave birth to a baby who rapidly became ill with meningitis and died in 5 days. Epidemiologic investigation revealed the following percentages of people who consumed the various food items: baked beans, 30%; ham, 80%; coleslaw, 60%; eclairs, 100%; and coffee, 90%. Which of the following statements is true?

Select one of the following:

  • This is not a case of food poisoning because only 4 people became ill

  • A relationship between the death of the baby and the food consumed at the
    church supper can be ruled out

  • Based on the epidemiologic investigation, the eclairs can be isolated as the
    source of the disease

  • Based on the epidemiologic investigation, the baked beans can be ruled out as
    the source of the disease

  • Additional epidemiologic data should include the percentage of those who ate
    a particular food item who became ill

Explanation

Question 7 of 77

1

Microbiologic analysis revealed no growth in the baked beans, ham,
or coffee; many Gram-positive beta-hemolytic, short, rod-shaped bacteria
in the coleslaw; and rare Gram-positive cocci in the eclairs. The most likely
cause of this outbreak is

Select one of the following:

  • Staphylococcus aureus

  • Listeria

  • Clostridium perfringens

  • Clostridium botulinum

  • Nonmicrobiologic

Explanation

Question 8 of 77

1

A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week.
Based on the information given, which of the following laboratory tests would most rapidly assist you in making the diagnosis?

Select one of the following:

  • Cold agglutinins

  • Viral culture

  • Complement fixation (CF) test

  • Gram stain of sputum

  • Culture of sputum

Explanation

Question 9 of 77

1

A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week.
The following laboratory data were available within 2 days: cold agglutinins—negative; complement fixation (M. pneumoniae)—1:64; viral culture—pending, but negative to date; bacterial culture of sputum on blood agar and MacConkey’s agar—normal oral flora. In order to confirm the diagnosis, which of the following procedures could be ordered to achieve a specific and sensitive diagnosis?

Select one of the following:

  • Culture of the sputum on charcoal yeast extract

  • A repeat cold agglutinin test

  • A DNA probe to the 16S ribosomal RNA of an organism lacking a cell wall

  • A repeat CF test in 5 days

  • Another viral culture in 1 week

Explanation

Question 10 of 77

1

Pathogenic mechanisms involved in tuberculosis can be primarily attributed to which of the following?

Select one of the following:

  • Toxin production by the mycobacteria

  • Specific cell adhesion sites

  • Cell-mediated hypersensitivity

  • Humoral immunity

  • Clogging of alveoli by large numbers of acid-fast mycobacteria

Explanation

Question 11 of 77

1

The class of antibiotics known as the quinolones are bactericidal. Their mode of action on growing bacteria is thought to be

Select one of the following:

  • Inhibition of DNA gyrase

  • Inactivation of penicillin-binding protein II

  • Inhibition of β-lactamase

  • Prevention of the cross-linking of glycine

  • Inhibition of reverse transcriptase

Explanation

Question 12 of 77

1

Vancomycin-indeterminate S. aureus (VISA) has recently been reported in the United States. Which one of the statements concerning VISA is the most correct?

Select one of the following:

  • Minimum inhibitory concentration (MIC) for vancomycin is at least 1.0 mcg/mL

  • VISA isolates are usually methicillin susceptible (methicillin-resistant S. aureus,
    MRSA)

  • VISAs have emerged because of the extended use of vancomycin for MRSAs

  • Patients with VISA isolates need not be isolated

  • VISA isolates are infrequent, so surveillance at the present time is not warranted

Explanation

Question 13 of 77

1

A sputum sample was brought to the laboratory for analysis. Gram stain revealed the following: rare epithelial cells, 8 to 10 polymorphonuclear leukocytes per high-power field, and pleomorphic Gram-negative rods. As the laboratory consultant, which of the following interpretations should you make?

Select one of the following:

  • The sputum specimen is too contaminated by saliva to be useful

  • There is no evidence of an inflammatory response

  • The patient has pneumococcal pneumonia

  • The patient has Vincent’s disease

  • The appearance of the sputum is suggestive of Haemophilus pneumonia

Explanation

Question 14 of 77

1

An isolate from a wound culture is a Gram-negative rod identified as Bacteroides fragilis. Anaerobic infection with B. fragilis is characterized by

Select one of the following:

  • A foul-smelling discharge

  • A black exudate in the wound

  • An exquisite susceptibility to penicillin

  • A heme-pigmented colony formation

  • Severe neurologic symptoms

Explanation

Question 15 of 77

1

Virtually all prokaryotic cells (bacteria, both Gram-positive and Gramnegative) contain peptidoglycan as well as specific enzymes for its synthesis. All of the following statements concerning Gram-positive and Gram-negative bacteria are true except

Select one of the following:

  • The extent of cross-linking of peptidoglycan is a function of different species of
    bacteria

  • The peptidoglycan-synthesizing enzymes can be antibiotic targets

  • Both Gram-positive and Gram-negative bacteria contain significant amounts of
    teichoic acid

  • With the exception of the structures that are cross-linked, peptidoglycan structure
    is common to most bacteria

  • The physical shape of bacteria is a function of peptidoglycan

Explanation

Question 16 of 77

1

L. monocytogenes causes a variety of diseases, including food poisoning. Listeria are small, Gram-positive, motile rod-shaped bacteria. Which of the following best describes these microorganisms?

Select one of the following:

  • Listeria are facultative intracellular pathogens

  • Once infected, the immune system cannot destroy Listeria

  • Listeria cannot be cultivated on artificial media

  • Flagella are produced both at room temperature and at 37°C

  • There is no relationship between Listeria serovars and human infection

Explanation

Question 17 of 77

1

A 30-year-old male patient was seen by the emergency service and reported a 2-week history of a penile ulcer. He noted that this ulcer did not hurt. Which one of the following conclusions/actions is most valid?

Select one of the following:

  • Draw blood for a herpes antibody test

  • Perform a dark-field examination of the lesion

  • Prescribe acyclovir for primary genital herpes

  • Even if treated, the lesion will remain for months

  • Failure to treat the patient will have no untoward effect, as this is a self-limiting
    infection

Explanation

Question 18 of 77

1

A 30-year-old male patient was seen by the emergency service and reported a 2-week history of a penile ulcer. He noted that this ulcer did not hurt. The laboratory reports that the Venereal Disease Research Laboratory (VDRL) test performed on the above patient is reactive at a dilution of 1:4 (4 dils). The patient also reports to you that he has recently been diagnosed with hepatitis A. Which one of the following actions would be most appropriate?

Select one of the following:

  • Report this patient to the health department, as he has syphilis

  • Order a confirmatory test such as the fluorescent treponemal antibody test
    (FTA)

  • Repeat the VDRL test

  • Order a rapid reagin test (RPR)

  • Perform a spinal tap to rule out central nervous system syphilis

Explanation

Question 19 of 77

1

A 30-year-old male patient was seen by the emergency service and reported a 2-week history of a penile ulcer. He noted that this ulcer did not hurt. The laboratory reports that the Venereal Disease Research Laboratory (VDRL) test performed on the above patient is reactive at a dilution of 1:4 (4 dils). The patient also reports to you that he has recently been diagnosed with hepatitis A. Which one of the following test combinations for syphilis is most appropriate?

Select one of the following:

  • FTA-Abs (IgG)/FTA-Abs (IgM)

  • RPR/FTA-Abs

  • RPR/culture of the lesion

  • VDRL/RPR

  • Treponema pallidum hemagglutination (TPHA)/microhemagglutination-Treponema
    pallidum (MHTP) tests

Explanation

Question 20 of 77

1

Assume that the patient absolutely denied any contact, sexual or otherwise, with a person who had syphilis. Assume also that both the RPR and the FTA Abs were positive on this patient. Which one of the following tests could be used to show that this patient probably does not have syphilis?

Select one of the following:

  • VDRL

  • Quantitative RPR

  • Treponema pallidum immobilization (TPI) test

  • Frei test

  • MHTP test

Explanation

Question 21 of 77

1

A 55-year-old man who is being treated for adenocarcinoma of the lung is admitted to a hospital because of a temperature of 38.9°C (102°F), chest pain, and a dry cough. Sputum is collected. Gram’s stain of the sputum is unremarkable and culture reveals many small Gram-negative rods able to grow only on a charcoal yeast extract agar. This organism most likely is

Select one of the following:

  • Klebsiella pneumoniae

  • Mycoplasma pneumoniae

  • Legionella pneumophila

  • Chlamydia trachomatis

  • S. aureus

Explanation

Question 22 of 77

1

A patient was hospitalized after an automobile accident. The wounds became infected and the patient was treated with tobramycin, carbenicillin, and clindamycin. Five days after antibiotic therapy was initiated, the patient developed severe diarrhea and pseudomembranous enterocolitis. Antibiotic-associated diarrhea and the more serious pseudomembranous enterocolitis can be caused by

Select one of the following:

  • Clostridium sordellii

  • Clostridium perfringens

  • Clostridium difficile

  • S. aureus

  • B. fragilis

Explanation

Question 23 of 77

1

Assuming that the average achievable serum level of gentamicin is 6 to 8 mcg/mL, which of the following bacteria is susceptible to gentamicin?

Select one of the following:

  • E. coli with a minimal inhibitory concentration (MIC) of 10 mcg/mL

  • E. coli with an MIC of 12 mcg/mL

  • Klebsiella with an MIC of 0.25 mcg/mL

  • Klebsiella with an MIC of 6.0 mcg/mL

  • Klebsiella with an MIC of 20 mcg/mL

Explanation

Question 24 of 77

1

A child comes to an emergency room because of an infected dog bite. The wound is found to contain small Gram-negative rods. The most likely cause of infection is

Select one of the following:

  • E. coli

  • H. influenzae

  • Pasteurella multocida

  • Brucella canis

  • Klebsiella rhinoscleromatis

Explanation

Question 25 of 77

1

A patient complained to his dentist about a draining lesion in his mouth. A Gram’s stain of the pus showed a few Gram-positive cocci, leukocytes, and many branched Gram-positive rods. The most likely cause of the disease is

Select one of the following:

  • Actinomyces israelii

  • Actinomyces viscosus

  • C. diphtheriae

  • Propionibacterium acnes

  • S. aureus

Explanation

Question 26 of 77

1

A man who has a penile chancre appears in a hospital’s emergency service. The VDRL test is negative. The most appropriate course of action for the physician in charge would be to

Select one of the following:

  • Send the patient home untreated

  • Repeat the VDRL test in 10 days

  • Perform dark-field microscopy for treponemes

  • Swab the chancre and culture on Thayer-Martin agar

  • Perform a Gram stain on the chancre fluid

Explanation

Question 27 of 77

1

Fever of unknown origin in a farmer who raises goats would most likely be caused by which of the following organisms?

Select one of the following:

  • Brucella melitensis

  • Clostridium novyi

  • T. pallidum

  • Histoplasma capsulatum

  • Mycobacterium tuberculosis

Explanation

Question 28 of 77

1

Cholera is a toxicogenic dysenteric disease common in many parts of the world. In the treatment of patients who have cholera, the use of a drug that inhibits adenyl cyclase would be expected to

Select one of the following:

  • Kill the patient immediately

  • Eradicate the organism

  • Increase fluid secretion

  • Reduce intestinal motility

  • Block the action of cholera toxin

Explanation

Question 29 of 77

1

A box of ham sandwiches with mayonnaise prepared by a person with a boil on his neck was left out of the refrigerator for the on-call interns. Three doctors became violently ill approximately 2 h after eating the sandwiches. The most likely cause is

Select one of the following:

  • S. aureus enterotoxin

  • Coagulase from S. aureus in the ham

  • S. aureus leukocidin

  • C. perfringens toxin

  • Penicillinase given to inactivate penicillin in the pork

Explanation

Question 30 of 77

1

S. aureus causes a wide variety of infections, ranging from wound infection to pneumonia. Treatment of S. aureus infection with penicillin is often complicated by the

Select one of the following:

  • Inability of penicillin to penetrate the membrane of S. aureus

  • Production of penicillinase by S. aureus

  • Production of penicillin acetylase by S. aureus

  • Lack of penicillin binding sites on S. aureus

  • Allergic reaction caused by staphylococcal protein

Explanation

Question 31 of 77

1

Symptoms of C. botulinum food poisoning include double vision, inability to speak, and respiratory paralysis. These symptoms are consistent with

Select one of the following:

  • Invasion of the gut epithelium by C. botulinum

  • Secretion of an enterotoxin

  • Endotoxin shock

  • Ingestion of a neurotoxin

  • Activation of cyclic AMP

Explanation

Question 32 of 77

1

In people who have sickle cell anemia, osteomyelitis usually is associated with which of the following organisms?

Select one of the following:

  • Micrococcus

  • Escherichia

  • Pseudomonas

  • Salmonella

  • Streptococcus

Explanation

Question 33 of 77

1

The treatment of choice for a patient with C. jejuni enterocolitis is

Select one of the following:

  • Erythromycin

  • Ciprofloxacin

  • Ampicillin

  • Pepto-Bismol

  • Campylobacter antitoxin

Explanation

Question 34 of 77

1

A hyperemic edema of the larynx and epiglottis that rapidly leads to respiratory obstruction in young children is most likely to be caused by

Select one of the following:

  • K. pneumoniae

  • M. pneumoniae

  • Neisseria meningitidis

  • H. influenzae

  • H. hemolyticus

Explanation

Question 35 of 77

1

A 70-year-old female patient was readmitted to a local hospital with fever and chills following cardiac surgery at a major teaching institution. Blood cultures were taken and a Gram-positive coccus grew from the blood cultures within 24 hours. Initial tests indicated that this isolate was resistant to penicillin. The most likely identification is

Select one of the following:

  • Streptococcus pneumoniae

  • Neisseria

  • Group A streptococcus

  • Enterococcus

  • Group B streptococcus

Explanation

Question 36 of 77

1

Acute hematogenous osteomyelitis is often diagnosed by isolation of the organism from the blood and is caused most often by

Select one of the following:

  • Proteus mirabilis

  • Streptococcus faecalis

  • Staphylococcus epidermidis

  • S. aureus

  • E. coli

Explanation

Question 37 of 77

1

Diphtheria toxin is produced only by those strains of C. diphtheriae that are

Select one of the following:

  • Glucose fermenters

  • Sucrose fermenters

  • Lysogenic for β-prophage

  • Of the mitis strain

  • Encapsulated

Explanation

Question 38 of 77

1

A 28-year-old menstruating woman appeared in the emergency room with the following signs and symptoms: fever, 104°F (40°C); WBC, 16,000/ μL; blood pressure, 90/65 mmHg; a scarlatiniform rash on her trunk, palms, and soles; extreme fatigue; vomiting; and diarrhea.
The patient described in the case above most likely has

Select one of the following:

  • Scalded skin syndrome

  • Toxic shock syndrome

  • Guillain-Barré syndrome

  • Chickenpox

  • Staphylococcal food poisoning

Explanation

Question 39 of 77

1

Culture of the menstrual fluid in the case of a woman with Toxic Shock Syndrome (TSS) would most likely reveal a predominance of

Select one of the following:

  • S. aureus

  • S. epidermidis

  • C. perfringens

  • C. difficile

  • Gardnerella vaginalis

Explanation

Question 40 of 77

1

A new latex agglutination (LA) reagent for H. influenzae polysaccharide antigen in cerebrospinal fluid was evaluated. Results were compared with the isolation of H. influenzae from the CSF. Results were as follows:
LA POS, CULT POS: 25
LA POS, CULT NEG: 5
LA NEG, CULT POS: 5
LA NEG, CULT NEG: 95
The sensitivity of LA is

Select one of the following:

  • 0%

  • 30%

  • 85%

  • 95%

  • 100%

Explanation

Question 41 of 77

1

A new latex agglutination (LA) reagent for H. influenzae polysaccharide antigen in cerebrospinal fluid was evaluated. Results were compared with the isolation of H. influenzae from the CSF. Results were as follows:
LA POS, CULT POS: 25
LA POS, CULT NEG: 5
LA NEG, CULT POS: 5
LA NEG, CULT NEG: 95
The specificity of LA is

Select one of the following:

  • 0%

  • 30%

  • 80%

  • 95%

  • 100%

Explanation

Question 42 of 77

1

A new latex agglutination (LA) reagent for H. influenzae polysaccharide antigen in cerebrospinal fluid was evaluated. Results were compared with the isolation of H. influenzae from the CSF. Results were as follows:
LA POS, CULT POS: 25
LA POS, CULT NEG: 5
LA NEG, CULT POS: 5
LA NEG, CULT NEG: 95
The negative predictive value of LA is

Select one of the following:

  • 10%

  • 80%

  • 95%

  • 110%

  • Not calculable

Explanation

Question 43 of 77

1

The incidence of H. influenzae meningitis in the general population is less than 1%. If during an epidemic the incidence rose to 3%, the negative predictive value of the LA test would

Select one of the following:

  • Increase

  • Decrease

  • Remain the same

  • Be impossible to calculate

  • Vary as a function of the specificity of the LA test

Explanation

Question 44 of 77

1

Methicillin-resistant S. aureus (MRSA) was isolated from 7 patients in a 14-bed intensive care unit. All patients were isolated and the unit closed to any more admissions. Which one of the following reasons best explains these rigorous methods to control MRSA?

Select one of the following:

  • MRSA is inherently more virulent than other staphylococci

  • The alternative for treatment of MRSA is vancomycin, an expensive and potentially
    toxic antibiotic

  • MRSA causes toxic shock syndrome

  • MRSA spreads more rapidly from patient to patient than antibiotic-susceptible
    staphylococci do

  • MRSA is resistant to penicillin

Explanation

Question 45 of 77

1

A patient with AIDS returned from Haiti with acute diarrhea. The stool revealed an oval organism (8 to 9 μm in diameter) that was acid-fast and fluoresced blue under ultraviolet light. The most likely identification of this organism is

Select one of the following:

  • Cyclospora

  • Giardia

  • Enterocytozoon

  • Cryptosporidium

  • Prototheca

Explanation

Question 46 of 77

1

A 2-year-old infant is brought to the emergency room with hemolytic uremic syndrome and thrombocytopenia. Which one of the following bacteria would most likely be isolated from a stool specimen?

Select one of the following:

  • Shigella

  • Salmonella

  • Aeromonas

  • E. coli 0157/H7

  • Enterobacter

Explanation

Question 47 of 77

1

E. coli causes disease by a variety of different methods. Which one of the following E. coli types is characterized by the presence of LT (heat-labile) and ST (heat-stable) proteins?

Select one of the following:

  • Enteroinvasive (EIEC)

  • Enterotoxigenic (ETEC)

  • Enterohemorrhagic (EHEC)

  • Enteropathogenic (EPEC)

  • Enterohemolytic (EHEEC)

Explanation

Question 48 of 77

1

Yersinia pestis, the causative agent of plague, is enzootic in the United States west of the one-hundredth meridian. Human plague can be bubonic or pneumonic. The primary epidemiologic difference between the two clinical forms of plague is

Select one of the following:

  • Season of the year

  • Route of infection

  • Age of the patient

  • Health of the animal vector

  • Geographic location of the animal vector

Explanation

Question 49 of 77

1

A 9-year-old child is brought to the emergency room with the chief complaint of enlarged, painful axillary lymph nodes. The resident physician also notes a small, inflamed, dime-sized lesion surrounding what appears to be a small scratch on the forearm. The lymph node is aspirated and some pus is sent to the laboratory for examination. A Warthin-Starry silver impregnation stain reveals many highly pleomorphic, rod-shaped bacteria. The most likely cause of this infection is

Select one of the following:

  • Y. pestis

  • Yersinia enterocolitica

  • Mycobacterium scrofulaceum

  • B. canis

  • Bartonella henselae

Explanation

Question 50 of 77

1

Recently, there have been sensational media reports of patients infected with invasive, “flesh-eating” bacteria that spread rapidly through the tissues. This necrotizing fasciitis is usually caused by

Select one of the following:

  • S. aureus

  • Group A streptococci

  • Micrococcus

  • Bacillus cereus

  • Clostridium tetani

Explanation

Question 51 of 77

1

The most effective noninvasive test for the diagnosis of Helicobacter-associated gastric ulcers is

Select one of the following:

  • Detection of H. pylori antigen in stool

  • Growth of H. pylori from a stomach biopsy

  • Growth of H. pylori in the stool

  • IgM antibodies to H. pylori

  • Culture of stomach contents for H. pylori

Explanation

Question 52 of 77

1

The following test results were observed in a woman tested in November who reported being in the woods in Pennsylvania during the past summer, was bitten by a tick, and now has Bell’s palsy: Lyme IgG antibody 1:1280; Lyme IgM antibody negative. Which one of the following courses of action is most appropriate?

Select one of the following:

  • Order tests for syphilis (VDRL, FTA-ABS) because there are cross-reactions reported with Borrelia burgdorferi

  • Ask the patient if she has a severe headache

  • Consider treatment of the patient with an appropriate antibiotic such as tetracycline

  • Ask the patient if she has had a urinary tract infection with E. coli

  • Ignore the results because there is no Lyme disease in Pennsylvania

Explanation

Question 53 of 77

1

Mycobacterium avium is a major opportunistic pathogen in AIDS patients. M. avium from AIDS patients can be best characterized by which one of the following statements?

Select one of the following:

  • The majority of M. avium isolates from AIDS patients are nonpigmented

  • M. avium isolates from AIDS patients are of multiple serovars

  • Few isolates from AIDS patients are acid-fast

  • Most isolates from AIDS patients are sensitive to isoniazid and streptomycin

  • M. avium can be isolated from the blood of AIDS patients

Explanation

Question 54 of 77

1

Rheumatic fever (RF) is a disease seen in children and young adults. Which one of the following statements best typifies the disease?

Select one of the following:

  • It is characterized by inflammatory lesions that may involve the heart, joints, subcutaneous tissues, and the central nervous system

  • The pathogenesis is related to the similarity between a staphylococcal antigen and a human cardiac antigen

  • Prophylaxis with benzathine penicillin is of little value

  • It is a complication of group A streptococcal skin disease but usually not of pharyngitis

  • It is very common in developing countries but extremely rare and decreasing in incidence in the United States

Explanation

Question 55 of 77

1

Bacteria cause disease in a number of ways. One mechanism of pathogenesis is the secretion of potent protein toxins. All the following diseases are caused by microbial protein toxins, but one toxin has been used for a variety of maladies. It is

Select one of the following:

  • Tetanus

  • Botulism

  • Bacillary (Shigella) dysentery

  • Diphtheria

  • Disseminated intravascular coagulation

Explanation

Question 56 of 77

1

A 2-year-old child was admitted to the hospital with acute meningitis. The Gram stain revealed Gram-positive short rods, and the mother indicated that the child had received “all” of the meningitis vaccinations. What is the most likely cause of the disease?

Select one of the following:

  • N. meningitidis, group A

  • N. meningitidis, group C

  • Listeria

  • S. pneumoniae

  • H. influenzae

Explanation

Question 57 of 77

1

The most common portal of entry for C. tetani, the cause of tetanus, is the

Select one of the following:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explanation

Question 58 of 77

1

The most common way in which tuberculosis is acquired is via the

Select one of the following:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explanation

Question 59 of 77

1

Shigellosis is common in travelers to developing countries. Infection is commonly acquired through the

Select one of the following:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explanation

Question 60 of 77

1

A person who contracts gonorrhea is most likely to have acquired it via the

Select one of the following:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explanation

Question 61 of 77

1

There are a variety of “unusual” bacteria that infect humans. While rare, disease caused by these microorganisms is serious and occasionally difficult to identify. Branhamella is best characterized as

Select one of the following:

  • A Gram-negative pleomorphic rod that can cause endocarditis

  • The causative agent of trench fever

  • A Gram-negative rod, fusiforme-shaped, that is associated with periodontal disease but may cause sepsis

  • The causative agent of rat-bite fever

  • The causative agent of sinusitis, bronchitis, and pneumonia

Explanation

Question 62 of 77

1

Cardiobacterium is best characterized as

Select one of the following:

  • A Gram-negative pleomorphic rod that can cause endocarditis

  • The causative agent of trench fever

  • A Gram-negative rod, fusiforme-shaped, that is associated with periodontal disease
    but may cause sepsis

  • The causative agent of rat-bite fever

  • The causative agent of sinusitis, bronchitis, and pneumonia

Explanation

Question 63 of 77

1

Capnocytophyga is best characterized as

Select one of the following:

  • A Gram-negative pleomorphic rod that can cause endocarditis

  • The causative agent of trench fever

  • A Gram-negative rod, fusiforme-shaped, that is associated with periodontal disease but may cause sepsis

  • The causative agent of rat-bite fever

  • The causative agent of sinusitis, bronchitis, and pneumonia

Explanation

Question 64 of 77

1

An enterococcus (E. faecium) was isolated from a urine specimen (100,000 cfu/mL). Treatment of the patient with ampicillin and gentamicin failed. The most clinically appropriate action is

Select one of the following:

  • Do no further clinical workup

  • Suggest to the laboratory that low colony counts may reflect infection

  • Determine if fluorescent microscopy is available for the diagnosis of actinomycosis

  • Consider vancomycin as an alternative drug

  • Suggest a repeat antibiotic susceptibility test

Explanation

Question 65 of 77

1

A patient with symptoms of urinary tract infection had a culture taken, which grew 5 × 103 E. coli. The laboratory reported it as “insignificant.” The most clinically appropriate action is

Select one of the following:

  • Do no further clinical workup

  • Suggest to the laboratory that low colony counts may reflect infection

  • Determine if fluorescent microscopy is available for the diagnosis of actinomycosis

  • Consider vancomycin as an alternative drug

  • Suggest a repeat antibiotic susceptibility test

Explanation

Question 66 of 77

1

A patient appeared in the emergency room with a submandibular mass. A smear was made of the drainage and a bewildering variety of bacteria were seen, including branched, Gram-positive rods. The most clinically appropriate action is

Select one of the following:

  • Do no further clinical workup

  • Suggest to the laboratory that low colony counts may reflect infection

  • Determine if fluorescent microscopy is available for the diagnosis of actinomycosis

  • Consider vancomycin as an alternative drug

  • Suggest a repeat antibiotic susceptibility test

Explanation

Question 67 of 77

1

The antibiotic therapy of choice for legionellosis is

Select one of the following:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explanation

Question 68 of 77

1

The antibiotic of choice for pneumococcal pneumonia is

Select one of the following:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explanation

Question 69 of 77

1

The antibiotic of choice for Lyme disease is

Select one of the following:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explanation

Question 70 of 77

1

The antibiotic of choice for streptococcal pharyngitis is

Select one of the following:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explanation

Question 71 of 77

1

The therapy of choice for pseudomembranous enterocolitis is

Select one of the following:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explanation

Question 72 of 77

1

C. jejuni is best described as

Select one of the following:

  • “String-test”-positive isolate; three serotypes—Ogawa (AB), Inaba (AC), Hikojima (ABC)

  • Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin

  • Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of cooked seafood

  • Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42°C

  • Urease-positive; cause of fetal distress in cattle

Explanation

Question 73 of 77

1

V. cholerae, the causative agent of cholera, is best described as

Select one of the following:

  • “String-test”-positive isolate; three serotypes—Ogawa (AB), Inaba (AC), Hikojima (ABC)

  • Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin

  • Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of cooked seafood

  • Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42°C

  • Urease-positive; cause of fetal distress in cattle

Explanation

Question 74 of 77

1

V. parahaemolyticus, first described in Japan, is best characterized as

Select one of the following:

  • “String-test”-positive isolate; three serotypes—Ogawa (AB), Inaba (AC), Hikojima (ABC)

  • Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin

  • Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of cooked seafood

  • Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42°C

  • Urease-positive; cause of fetal distress in cattle

Explanation

Question 75 of 77

1

Vibrio vulnificus, which can be found in the oceans and bays in temperate and tropical climates, is best characterized as

Select one of the following:

  • “String-test”-positive isolate; three serotypes—Ogawa (AB), Inaba (AC), Hikojima (ABC)

  • Human pathogen, halophilic, lactose-positive; produces heat-labile, extracellular toxin

  • Human pathogen, halophilic, lactose-negative, sucrose-negative; causes gastrointestinal diseases primarily from ingestion of cooked seafood

  • Cause of gastroenteritis; reservoir in birds and mammals, optimal growth at 42°C

  • Urease-positive; cause of fetal distress in cattle

Explanation

Question 76 of 77

1

Y. enterocolitica, formerly a Pasteurella, is best described by which of the following statements?

Select one of the following:

  • Commonly inhabits the canine respiratory tract and is an occasional pathogen for humans; strongly urease-positive

  • Pits agar, grows both in carbon dioxide and under anaerobic conditions, and is part of the normal oral cavity flora

  • Typically infects cattle, requires 5 to 10% carbon dioxide for growth, and is inhibited by the dye thionine

  • Typically is found in infected animal bites in humans and can cause hemorrhagic septicemia in animals

  • Manifests different biochemical and physiologic characteristics, depending on growth temperature, and causes a spectrum of human disease, most commonly mesenteric lymphadenitis

Explanation

Question 77 of 77

1

Brucella abortus, one of the three species causing brucellosis, a possible bioterrorism agent, is best described by which of the following statements?

Select one of the following:

  • Commonly inhabits the canine respiratory tract and is an occasional pathogen for humans; strongly urease-positive

  • Pits agar, grows both in carbon dioxide and under anaerobic conditions, and is part of the normal oral cavity flora

  • Typically infects cattle, requires 5 to 10% carbon dioxide for growth, and is inhibited by the dye thionine

  • Typically is found in infected animal bites in humans and can cause hemorrhagic septicemia in animals

  • Manifests different biochemical and physiologic characteristics, depending on growth temperature, and causes a spectrum of human disease, most commonly mesenteric lymphadenitis

Explanation

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