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Bacteriology Pre-test Microbiology

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Pre-Test Microbiology - Bacteriology

Pregunta 1 de 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

Selecciona una de las siguientes respuestas posibles:

  • Campylobacter jejuni

  • Vibrio parahaemolyticus

  • Haemophilus influezae

  • Helicobacter pylori

  • Campylobacter fetus

Explicación

Pregunta 2 de 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

Selecciona una de las siguientes respuestas posibles:

  • Vibrio cholerae

  • Corynebacterium diphtheriae

  • Pseudomonas

  • Listeria monocytogenes

  • Brucella

Explicación

Pregunta 3 de 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

Selecciona una de las siguientes respuestas posibles:

  • Exotoxin liberator

  • Endotoxin assembly

  • Flagella synthesis

  • Capsule formation

  • IgA protease synthesis

Explicación

Pregunta 4 de 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

Selecciona una de las siguientes respuestas posibles:

  • Mycoplasma pneumonia

  • Pneumococcal pneumonia

  • Staphylococcal pneumonia

  • Influenza

  • Legionellosis

Explicación

Pregunta 5 de 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

Selecciona una de las siguientes respuestas posibles:

  • Immunologic anergy

  • Chronic pneumonitis

  • Peripheral neuritis

  • Bacilli in lesions that digest tissues

  • Erythematous lesions resembling concentric circles

Explicación

Pregunta 6 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 7 de 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

Selecciona una de las siguientes respuestas posibles:

  • Staphylococcus aureus

  • Listeria

  • Clostridium perfringens

  • Clostridium botulinum

  • Nonmicrobiologic

Explicación

Pregunta 8 de 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?

Selecciona una de las siguientes respuestas posibles:

  • Cold agglutinins

  • Viral culture

  • Complement fixation (CF) test

  • Gram stain of sputum

  • Culture of sputum

Explicación

Pregunta 9 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 10 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Toxin production by the mycobacteria

  • Specific cell adhesion sites

  • Cell-mediated hypersensitivity

  • Humoral immunity

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

Explicación

Pregunta 11 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 12 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 13 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 14 de 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

Selecciona una de las siguientes respuestas posibles:

  • A foul-smelling discharge

  • A black exudate in the wound

  • An exquisite susceptibility to penicillin

  • A heme-pigmented colony formation

  • Severe neurologic symptoms

Explicación

Pregunta 15 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 16 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 17 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 18 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 19 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 20 de 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?

Selecciona una de las siguientes respuestas posibles:

  • VDRL

  • Quantitative RPR

  • Treponema pallidum immobilization (TPI) test

  • Frei test

  • MHTP test

Explicación

Pregunta 21 de 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

Selecciona una de las siguientes respuestas posibles:

  • Klebsiella pneumoniae

  • Mycoplasma pneumoniae

  • Legionella pneumophila

  • Chlamydia trachomatis

  • S. aureus

Explicación

Pregunta 22 de 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

Selecciona una de las siguientes respuestas posibles:

  • Clostridium sordellii

  • Clostridium perfringens

  • Clostridium difficile

  • S. aureus

  • B. fragilis

Explicación

Pregunta 23 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 24 de 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

Selecciona una de las siguientes respuestas posibles:

  • E. coli

  • H. influenzae

  • Pasteurella multocida

  • Brucella canis

  • Klebsiella rhinoscleromatis

Explicación

Pregunta 25 de 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

Selecciona una de las siguientes respuestas posibles:

  • Actinomyces israelii

  • Actinomyces viscosus

  • C. diphtheriae

  • Propionibacterium acnes

  • S. aureus

Explicación

Pregunta 26 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 27 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Brucella melitensis

  • Clostridium novyi

  • T. pallidum

  • Histoplasma capsulatum

  • Mycobacterium tuberculosis

Explicación

Pregunta 28 de 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

Selecciona una de las siguientes respuestas posibles:

  • Kill the patient immediately

  • Eradicate the organism

  • Increase fluid secretion

  • Reduce intestinal motility

  • Block the action of cholera toxin

Explicación

Pregunta 29 de 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

Selecciona una de las siguientes respuestas posibles:

  • S. aureus enterotoxin

  • Coagulase from S. aureus in the ham

  • S. aureus leukocidin

  • C. perfringens toxin

  • Penicillinase given to inactivate penicillin in the pork

Explicación

Pregunta 30 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 31 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Invasion of the gut epithelium by C. botulinum

  • Secretion of an enterotoxin

  • Endotoxin shock

  • Ingestion of a neurotoxin

  • Activation of cyclic AMP

Explicación

Pregunta 32 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Micrococcus

  • Escherichia

  • Pseudomonas

  • Salmonella

  • Streptococcus

Explicación

Pregunta 33 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Erythromycin

  • Ciprofloxacin

  • Ampicillin

  • Pepto-Bismol

  • Campylobacter antitoxin

Explicación

Pregunta 34 de 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

Selecciona una de las siguientes respuestas posibles:

  • K. pneumoniae

  • M. pneumoniae

  • Neisseria meningitidis

  • H. influenzae

  • H. hemolyticus

Explicación

Pregunta 35 de 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

Selecciona una de las siguientes respuestas posibles:

  • Streptococcus pneumoniae

  • Neisseria

  • Group A streptococcus

  • Enterococcus

  • Group B streptococcus

Explicación

Pregunta 36 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Proteus mirabilis

  • Streptococcus faecalis

  • Staphylococcus epidermidis

  • S. aureus

  • E. coli

Explicación

Pregunta 37 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Glucose fermenters

  • Sucrose fermenters

  • Lysogenic for β-prophage

  • Of the mitis strain

  • Encapsulated

Explicación

Pregunta 38 de 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

Selecciona una de las siguientes respuestas posibles:

  • Scalded skin syndrome

  • Toxic shock syndrome

  • Guillain-Barré syndrome

  • Chickenpox

  • Staphylococcal food poisoning

Explicación

Pregunta 39 de 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

Selecciona una de las siguientes respuestas posibles:

  • S. aureus

  • S. epidermidis

  • C. perfringens

  • C. difficile

  • Gardnerella vaginalis

Explicación

Pregunta 40 de 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

Selecciona una de las siguientes respuestas posibles:

  • 0%

  • 30%

  • 85%

  • 95%

  • 100%

Explicación

Pregunta 41 de 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

Selecciona una de las siguientes respuestas posibles:

  • 0%

  • 30%

  • 80%

  • 95%

  • 100%

Explicación

Pregunta 42 de 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

Selecciona una de las siguientes respuestas posibles:

  • 10%

  • 80%

  • 95%

  • 110%

  • Not calculable

Explicación

Pregunta 43 de 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

Selecciona una de las siguientes respuestas posibles:

  • Increase

  • Decrease

  • Remain the same

  • Be impossible to calculate

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

Explicación

Pregunta 44 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 45 de 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

Selecciona una de las siguientes respuestas posibles:

  • Cyclospora

  • Giardia

  • Enterocytozoon

  • Cryptosporidium

  • Prototheca

Explicación

Pregunta 46 de 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?

Selecciona una de las siguientes respuestas posibles:

  • Shigella

  • Salmonella

  • Aeromonas

  • E. coli 0157/H7

  • Enterobacter

Explicación

Pregunta 47 de 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?

Selecciona una de las siguientes respuestas posibles:

  • Enteroinvasive (EIEC)

  • Enterotoxigenic (ETEC)

  • Enterohemorrhagic (EHEC)

  • Enteropathogenic (EPEC)

  • Enterohemolytic (EHEEC)

Explicación

Pregunta 48 de 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

Selecciona una de las siguientes respuestas posibles:

  • Season of the year

  • Route of infection

  • Age of the patient

  • Health of the animal vector

  • Geographic location of the animal vector

Explicación

Pregunta 49 de 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

Selecciona una de las siguientes respuestas posibles:

  • Y. pestis

  • Yersinia enterocolitica

  • Mycobacterium scrofulaceum

  • B. canis

  • Bartonella henselae

Explicación

Pregunta 50 de 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

Selecciona una de las siguientes respuestas posibles:

  • S. aureus

  • Group A streptococci

  • Micrococcus

  • Bacillus cereus

  • Clostridium tetani

Explicación

Pregunta 51 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 52 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 53 de 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?

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 54 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 55 de 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

Selecciona una de las siguientes respuestas posibles:

  • Tetanus

  • Botulism

  • Bacillary (Shigella) dysentery

  • Diphtheria

  • Disseminated intravascular coagulation

Explicación

Pregunta 56 de 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?

Selecciona una de las siguientes respuestas posibles:

  • N. meningitidis, group A

  • N. meningitidis, group C

  • Listeria

  • S. pneumoniae

  • H. influenzae

Explicación

Pregunta 57 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explicación

Pregunta 58 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explicación

Pregunta 59 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explicación

Pregunta 60 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • Skin

  • Gastrointestinal tract

  • Respiratory tract

  • Genital tract

  • Nasal tract

Explicación

Pregunta 61 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 62 de 77

1

Cardiobacterium is best characterized as

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 63 de 77

1

Capnocytophyga is best characterized as

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 64 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 65 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 66 de 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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 67 de 77

1

The antibiotic therapy of choice for legionellosis is

Selecciona una de las siguientes respuestas posibles:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explicación

Pregunta 68 de 77

1

The antibiotic of choice for pneumococcal pneumonia is

Selecciona una de las siguientes respuestas posibles:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explicación

Pregunta 69 de 77

1

The antibiotic of choice for Lyme disease is

Selecciona una de las siguientes respuestas posibles:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explicación

Pregunta 70 de 77

1

The antibiotic of choice for streptococcal pharyngitis is

Selecciona una de las siguientes respuestas posibles:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explicación

Pregunta 71 de 77

1

The therapy of choice for pseudomembranous enterocolitis is

Selecciona una de las siguientes respuestas posibles:

  • Penicillin

  • Ampicillin

  • Erythromycin

  • Vancomycin

  • Ceftriaxone

Explicación

Pregunta 72 de 77

1

C. jejuni is best described as

Selecciona una de las siguientes respuestas posibles:

  • “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

Explicación

Pregunta 73 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • “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

Explicación

Pregunta 74 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • “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

Explicación

Pregunta 75 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • “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

Explicación

Pregunta 76 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 77 de 77

1

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

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación