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98 Cards in this Set
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A 67 year old diabetic women is hospitalized with a 3-day history of fever, headache, diarrhea, dyspnea, and a cough productive scant sputum. A chest radiograph reveals patchy, multilobar consolidation. No organisms are seen on sputum Gram stain; however, culture of sputum and blood on buffered charcoal yeast extract agar and blood agar are shown in the photograph. Bacteria from the colonies, stained with basic fuschin, are also shown. Direct lfuorescent antibody staining of cultured bacteria leads to a definitive diagnosis. With which organisms is the woman infected?
A. Actinomyces isrealii B. Corynebacterium diphtheriae C. Legionella pneumophilia D. Hemophilus influenza E. Nocardia asteroides |
C.
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What is the source of infection for the patient in the preceding question?
a. aerosolized spores fromsoil b. aerosis from contamined water c. colonization of the upper airays d. inapparent carrier of the organism e. person with the same disease |
b.
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A 5-year-old child died from severe septic shock, disseminated intravascular coagulation, and cardiac insufficiency following a sudden onset of fever, severe headache, and vomiting. The causative agent, a gram negative bacteria diplococcus, was isolated from blood and cerebrospinal fluid (CSF) on Thayer-Martin agar and was also identified in CSF by latex agglutination. What is the most important virulence factor involved in disease production by the etiologic agent in this case?
a. exotoxin production b. flagella c. lipooligosaccharide d. pili e. polysaccharide capsule |
c.
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Vaccination against which bacterial species has been most successful at reducing the number of cases of invasive disease, including meningitis?
a. Escherichia coli K1 b. Haemophilus influenza b c. Listeria monocytogenes d. Neisseria meningitidis e. Streptococcus pneumoniae |
b.
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A 56-year-old renal transplant patient was hospitalized following an abrupt onset of high fever (39.6 degrees C), confusion, headache, diarrhea, a cough productive of scant sputum, and shortness of breath, His chemistry profile revealed hyponatremia. A chest radiograph showed lobar infiltrates. Gram stain of sputum showed numerous neutrophils but failed to show any organisms. A urine antigen test was positive for the causative agent. What is the antigen test was positive for the causative agent. What is the major virulence factor of the causative agent?
a. antiphagocytic capsule b. cord factor c. cord factor d. intracellular growth e. pyocyanin |
d
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A steer dies on a ranch in North Dakota and a veterinarian is consulted. Histological sections of the spleen from decreased animal show evidence of a bacterial causative agent (shown in the photograph). The bacterium was also cultured aerobically on blood agar. Which of the following substances is associated with increased virulence of this isolate, and if detected, would alarm the state health officials and result in a more extensive investigation at the national level?
a. capsule b. h antigen c. hemolysin d. lipid a e. lipotechoic acid |
a
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The infected pressure sores were observed on the buttock of an elderly, bedridden patient recently treated for a malignancy of the rectum. Some of the lesions are conspicuously necrotic, exceptionally painful to the touch, and readily give off a musty sweet odor. Moreover, these lesions seem to have developed overnight. A Gram stain of the watery discharge from one of the lesions reveals an abundance of bacteria(show in the paragraph). What is the most likely diagnosis?
a. clostridial gas gangrene b. psuedomonas ecthyma gangrenosum c. staphylococcal celluitis d. staphyloccal pyomyositis e. streptococcal necrotizing fasciitis |
a
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What virulence factor is most important than considering pathology of this case?
a. alpha-toxin (lecithinase) b. enterotoxin c. pycocyanin d. pygrogenic exotoxin A e. streptolysin s |
a
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While planting a tree, a man punctured his foot through his tennis shoe with the prongs of a rake. He was not initially concerned with the wound and washed it only superficially. At 4:00 AM, he awakened with excruciating pain in the foot and sought medical care at the emergency apartment. The lesion was cleaned and excised of devitalized tissue and an IV beta-lactam antibiotic was administered, which subsequently cleared the infection. A Gram stain of an anaerobic culture taken from wound secretions is shown. Of the following microbial groups, which is most compatible with this case?
a. actinomyces b. clostridia c. psuedomnads d. staphylococci e. streptococci |
a
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A patient injured herself at home in the garden, and after several days, the resulting skin lesions became infected and intensely painful and she sought medical help. Culture of the wound grew Gram-positive cocci that were beta-hemolytic on blood agar. On nutrient agar, the organism produced effervescence when hydrogen peroxide was added to the colonies (shown in the photograph). What is the enzyme responsible for this bubbling?
a. b-lactamase b. catalase c. coagulase d. staphylokinase e. streptokinase |
b
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Of the following organisms, what is the patient most likely infected with?
a. clostridium sp. b. enterococcus c. group a strerptococcus d. meningococcus e. methicillin-resistant staphyloccous aureus (MRSA) |
e.
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Based on these initial findings, what is the best antibiotic choice for the patient in the above case?
a. amoxicillin/clavulnate b. cephalexin d. dicloxacillin d. polymyxin b e. trimethoprim-sulfamethoxazole (TMP-SMZ) |
e
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A pediatric patient with a persistent cough is evaluated for sinopulmonary disease. History and physical examination determines that the child suffers form nasal polyps and possibly, chronic airway obstruction. A sputum sample produces several bacterial species, including Haemophilus influenzae and a mucoid variety of psuedomonas aeruginosa. Which of the following is the most likely diagnosis?
a. bronchiolitis b. chronic obstructive pulmonary disease c. cystic fibrosis d. interstitial pneumonia e. sarcoidosis |
c
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During a medical mission to tropical Latin America, a woman presents with chronic infections of her foot as seen in the accompanying photograph. Secretions from the lesions, upon Gram staining, clearly reveal the presence of filamentous Gram-positive cells. Which bacterial species us descriptive of the offending agent?
a. Actinomyces israeli b. Blastomyces dermatidis c. Clostridium perferingens d. Myobacteria leprae e. Streptococcus pyogenes |
a.
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In early June a middle after African American male from rural southwestern Missouri is brought to the regional urgent care facility. He has been vomiting most of the night and it currently febrile. He complains of aching muscles and a throbbing headache. Rales are detected on auscultation. Physical examination reveals a petechial rash on the forearms and an engorged tick is removed from the groin area. Considering the particulars of the case, which of the following is the most crucial action that should be taken for successful management and a positive outcome.
a. aggressive management of fluid intake to prevent rehydration b. chest radiographic study to rule out interstitial pneumonia c. gram stain clean catch urine sample for evidence of a urinary tract infection d. immediate initiation of doxycycline e. submitting blood sample of immunodiagnosis to the lab |
d.
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With regard to the preceding case, which laboratory results would be most useful in confirming the clinical diagnosis?
a. introcytoplasmic inclusions in McCoy tissue culture cells b. positive bacterial growth on selective and differential media c. twofold increase in a Weil-Felix Proteus OX-19 titer d. type-specific latex agglutination antibody titter of 1:64 e. visualization of bacteria in the tissue by means of Gram stain |
d
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A Peace Corps agricultural advisor, which is stationed on an island, in the eastern Indian Ocean, becomes ill with headache, fever, and respiratory symptoms. At the local clinic, a prominent eschar on the abdomen just below the belt line is detected. Local physicians easily make a clinical diagnosis of an illness carried by rodents and transmitted by mites. Doxycycline therapy s empirically administered and the patient makes an uneventful recovery. What is the name of the illness and the etiologic agent?
a. Brill-Zinsser disease/Rickettsia rickettsiae b. Endemic typus/Rickettsia typhi c. Epidemic typhus/Rickettsia prowazeki d. Q fever/Coxielle burnetii e. Scrub typhus/Orientia tsutsugamushi |
e
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Physicians and state epidemiologists investigate a clued of acute diarrheal cases in children who attend a preschool in a small Midwestern town. The children represented with fever, acute episodes of bloody diarrhea and petechial rash or purport. Two of the children have scanty urine output and are showing signs of renal failure. Fecal leukocytes and parasites are absent in microscopic smears, and no obvious pathogens are identified using standard microbiologic media. What is the most common infectious agent consistent with this clinical picture?
a. Bacllus cereus b. Enterohemorrhagic Escherichia coli (EHEC) c. Salmonella typhi d. Shigellla flexneri e. Yersina enterocolitica |
b.
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The preschool in the preceding case only serves pasteurized milk and package cookies to the children and epidemiologists quickly rule out a food source a the risk factor. With this in mind, which of the following is the most plausible means by which the children were infected?
a. contagious transition from an infected child b. drinking water of the preschool is contaminated with the microbe c. failure to wash hands after visiting a petting zoo d. fecal-oral transmission, most likely from the restroom e. visiting the elderly in an assisted-living or nursing home facility? |
c.
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Medical outreach physicians, working in a refugee camp in central Africa, are concerted with the number of young children presenting with high fever, bloody diarrhea, and dehydration. The crowded living conditions of the camp suggest person to person contact, but because of the remoteness of the site only limited laboratory studies are available. The suspect culprit is described as a nonmotile, Gram-negative bacillus that does not produce lactose-positive colonies on sell five media. Based on these findings, which disease is more likely?
a. Bacillary dysentery b. Campylobacteriosis c. Cholera (O:1 classic biotype) d. Nontyphoidal salmonellosis e. Staphylococcal food poisoning |
a.
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A major virulence factor of the etiologic agent in the above question is a toxin. What is the role of this toxin in disease production?
a. acts as super antigen thereby including inflammation b. blocks protein synthesis causing intestinal cell death c. increase cAMP concentration within intestinal cells d. increases cGMP concentration within intestinal cells e. Suppresses cytokine secretion by immune cells |
c.
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What is the proper course of a cation the physicians should take with regard to the management of the outbreak described in the above case?
a. advise patient to increase their vitamin intake due to the effects of diarrhea b. avoid antibiotics and allow the symptoms to abate naturally c. avoid contact with animal reservoirs to prevent reintroduction of the organism into the community d. prescribe anti motility drugs to reduce transmission e. treat affected patients with antibiotics |
e.
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During the summer in western Massachusetts, a teenager complains of aching muscles and joints and mild fever. He notices a rash on the side of his upper leg (shown in the photograph), which prompts his mother to take him to the clinic. What is the most likely etiology and route of transmission?
a. Borrelia burgdorferi/tick bite b. Ehrlichia chaffeensis/tick bite c. Francisella tularensis/deer fly bite d. Leptospira interrogans/roden bite e. Necrotic arachnidism/spider bite |
a.
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How would the physician determine the diagnosis int he above case?
a. CBC assessment and visualization of the microbe from the lesion by dark field microscopy b. History and clinical presentation of the patient plus elevated liver function tests c. History and clinical presentation of the patient alone d. Culture of the organism from blood and synovial fluid e. Serologic test to detect antibodies in the patient serum against the organism |
c.
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With regard to the preceding case, what is the drug of choice?
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c.
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A 7-year-old female chid is taken to an urgent care facility because of fever and periodic incontinence. The physician suspects a urinary tract infection. What is the most likely etiology of this child's infection?
a. Escherichia coli b. Proteus mirabilis c. Pseudomonas aeruginosa d. Staphyloccous saprophyticus e. Ureaplasma urealyticum |
a.
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During gyneloc office visit, a positive leukocyte esterase test of the urine along with a voiding symptom prompts the physician to order a urine culture. The bacterium, which was isolated in clinically significant numbers, grows profusely on MacConkey agar, as shown in the accompanying photograph, and ferments lactose. Which of the following cellular attributes is most important in determining virulence and classifying this microbe as a uropathogen?
a. Beta-lactamase b. fimbriae c. flagella d. glycocalyx e. Urease |
b.
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With reference to the above case, what is the most likely source and mode of transmission for this urinary bacterial isolate?
a. contamination with perianal and bowel flora b. hematogenous spread form the kidneys c. inadvertent inoculation with commensal organism on skin d. transmission from an uncircumcised sexual partner e. waterborne spread |
a.
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a 78-year-old hospitalized male with an indwelling catheter developed a new onset of fever. The urine sample has an alkaline pH, The bacterium isolated from the rhine is a urease-producing, highly motile, Gram-negative bacillus. What is the most likely complication of this infection?
A. Deposition of antigen-antibody complexes in the glomeruli b. development of epididyitis c. development of prostatis d. formation of struvite kidney stones e. rapid dissemination throughout the body |
d.
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What is the pathogen most likely involved in the above case?
a. Escherichia coli b. Proteus mirabilis c. Psuedomonas aeruginosa d. Staphylococcus saprophyticus e. Ureaplasma urealyticum |
b.
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An 85-year-old male nursing home patient with a history of alcoholism suddenly developed a flu-like illness. He complained of chills and fever and had frequency coughing spells productive of thick, blood sputum. The attending physician diagnosed bronchopneumonia and prescribed antibiotics, but regrettably the patient died within a week. What is the most likely cause of the patient's pneumonia?
a. Haemophilus influenzae b. Klebsiella pneumoniae c. Legionella pneumophila d. Mycoplasma pneumoniae e. Streptococcus pneumoniae |
b.
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A bacterium, cultured on MacConkey agar (shown in the photograph), was isolated from sputum and blood of the patient in the above case. What is the primary function of the pathogenicity determinant depicted in this photo?
a. Antiphagocytic, unless opsonization occurs b. Degrades secretory IgA on mucosal surfaces c. Inhibits the function of complement d. Lyses neutrophils and macrophages e. Protease activity ad disrupts membranes |
a.
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A bacterium was isolated from the central nervous system of a newborn that died of meningitis. The vagina of the other was colonized with the same isolate as determined by the capsular antigens. The microbe grew well on standard blood and MacConkey agar at ambient atmospheric conditions. What is the most likely etiologic agent?
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a.
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An adult tourist visiting a remote area of Guatemala developed fever, prostration, malaise, dysentery, and dehydration. Based on current epidemiological data of the region, a local physician reported that the causative agent was probably a diarrhegenic strain of Escherichia coli and did not prescribe antibiotic therapy. Presuming the Guatemelan doctor to be correct, which type of virulent E. coli is most consistent with this clinical picture?
a. Enteroaggregative E. coli (EAEC) b. Enterogemorrhagic E coli (EHEC) c. Enteroinvasive E. coli (EIEC) d. Enteropathogenic E. coli (EPEC) e. Enterotoxigenic E. coli (ETEC) |
c.
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A 40-year-old man presented with a rubeola like rash on the extremities, chills, fever, myalgia, and malaise 5 days after returning from a June fishing trip in Arkansas. A history of tick bites is noted and Rocky Mountain spotted fever (RMSF) is suspected. What is the etiologic agent?
A. Babesia microti b. Orienta tsutsugamushi c. Rickettsia prowazeki d. Rickettsia rickettsii e. Rickettsia typhi |
d.
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With reference to the above question, which antimicrobial agent should be employed?
a. Chloramphenicol b. ciprofloxacin c. doxycycline d. penicillin g e. tmp-smz |
c.
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A previously healthy woman became nauseated and vomits 12 hours after eating home-pickled eggs. Within 24 hours, she developed a diffuse flaccid paralysis and respiratory impairment, necessitating hospitalization and mechanical ventilation. Other symptoms included diplopia and dysarthria. What is the most likely diagnosis?
a. Botulism b. Brucellosis c. Gastrointestinal anthrax d. Legionellosis e. Meningococcal disease |
a.
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A 52-year-old woman presented with indigestion and heartburn occurring shortly after meals which she treated with over-the-counter antacids. Physical examination reveals mild epigastric tenderness. A radiolabeled-uea breath test is positive. What is the most probable etiologic agent?
a. Campylobacter jejuni b. Clostridium difficile c. Heliobacter pylori d. Shigella dysenteriae e. Yersina enterocolitica |
c.
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What cancer is the patient in the above case at risk for as a consequent e of this infection?
a. Pancreatic cancer b. Gastric adenocarcinoma c. hepatoma d. Colon Cancer e. Esophageal cancer |
b.
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What virulence factor of the organism may be associated with induction of this cancer?
a. cgA b. Heart shock protein B c. Mucinase d. Urease e. Vacuolating cytotoxin |
a.
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Hemorrhagic colitis, hemolytic uremic syndrome, and thrombotic thrombocytopenic purport are clinical manifestation of which bacterial species?
a. Campylobacter jejuni b. Escherichia coli O15:H7 c. Shigella flexneri d. Vibrio cholerae e. Yersina enterocolitica |
b.
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Over the course of a summer, several patient present to hospitals in the northwestern United States with complaints of fever, chills, headache, and other viral-like symptoms. Reportedly with many of these patients, the fever subsides only to return with a vengeance later. Of significance is that spirochetes are observed in peripheral blood smears. Another common denominator is that all patients are outdoor enthusiast and frequently engage in activities like camping, fishing and hiking in mountainous areas. What is the most likely etiologic agent?
a. Boreilla hermsii b. Treponea pallidum c. Rickettsia rickettsiae d. Proteus vulgaris e. Vibrio vulnificus |
a.
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A 23-year-old male presented with ulcerated lesions on the penis s shown in the accompanying photograph as well as marked unilateral inguinal lymphadenopathy. The lymph node, however, is not particularly painful to the touch. The patient denies abnormal discharge any discomfort during intercourse. he is presently afebrile. Consistent with the presentation, what is the probably causative etiology?
a. Chlamydia trachomatis b. Haeomphilus duceryi c. Neisseria gonorrhoeae d. Treponema pallidum e. Trichomonas vaginalis |
d.
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A 20-year-old pregnant partner o the above patient presented with a 2-wekk history of flu-like symptoms. Physical examination reveals a generalized contender lymphadenopathy and numerous discrete cutaneous hyperpigmentations on the soles of the feet as shown in the accompanying photograph. Which of the following laboratory procedures would give you a definitive diagnosis?
a. Bacteriologic culture b. Giesma-stained histological section c. Gram-stained smear d. Growth in cell culture e. Specific antibody test |
e.
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Assuming that the patient in the above case has no drug allures, which antibiotic would be the best choice for treatment?
a. Ciprofloxacin b. Doxycycline c. Metronidazole d. Penicillin e. TMP-SMZ |
d.
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A 5-day old postoperative patient develops a high fever. An IV catheter is removed and culture of the tip reveals Gram-positive cocci believe to be Staphylococcus aureus. Which of the following laboratory test results would further support this belief?
a. α-hemolysis on blood agar b. Bacitracin sensitivity c. Coagulase positivity d. Lactose fermentation e. Urea hydrolysis |
c.
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A high school student who was appropriately immunized with the diphtheriae-tetanus acceular pertussis (DTaP) series by kindergarten, but who had received no additional boosters since, stepped on a nail while walking barefoot. The nail was easily removed and the lesion freely bled. What should the student be given?
a. Equine tetanus antitoxin b. Human tetanus immune globulin c. Prophylactic antibiotic treatment for Clostridium tetani d. No treatment e. Tetanus toxoid |
e.
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The Gram-stained smear of urethral exudate from a male (shown in the photo) is diagnostic for which disease?
a. Chancroid b. Gonorrhea c. Lymphogranuloma venereum d. Nongonococcal urethritis e. Primary syphilis |
b.
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What is the appropriate therapy for the patient int he above case, assuming no further tests were conducted?
a. Ceftriaxone b. Certriaxone plus azithromycin b. Ciprofloxacine d. Penicillin e. Tetracycline |
b.
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A 24-year-old woman presents with a vagina discharge that is characterized by a thin milky appearance, a marked amine odor, and a pH of 4.5. A Gram-stain of the vaginal discharge is shown in the photograph. What is the most likely diagnosis?
a. atrophic vaginitis b. bacterial vaginosis c. Gonorrhea d. Group B colonization e. Trichomonas vaginalis infection |
b.
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A tube dilution panel for a particular antibiotic gives results as illustrated in the accompanying photograph. With regard to the sensitivity of this particular bacterial isolate to the antibiotic tested, which statement is true?
a. Results reflect the bacteriostatic properties of the antibiotic b. The antibiotic is bactericidal at all tube dilution concentrations c. The minimum inhibitory concentration (MIC) is 8 mcg/mL d. The MIC is >>32 mcg/mL e. The minimum bactericidal concentration (MBC) is 16 mcg/mL |
a.
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A preschool-aged child from Georgia is hospitalized because of edema and hematuria. Of note is that the child was recently successfully treated for a pyoderma (see photo). Which microbe is likely associated with this child's condition?
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d.
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A 37-year-old man presented with a 2 day history of low grade fever, abdominal cramps diarrhea, nausea, and vomiting. One day prior to the onset of symptoms, six family members had eaten at an all-you-can-eat fried chicken buffet. Two other members of his family (his 82-year-old mother had a 14-month old son) had similar symptoms. Examination of a fecal smear from the patient reveals abundant fecal leukocytes. Which of the following laboratory profiles is consistent with the most likely microbial cause of this man's condition?
a. Aerobic, β-hemolytic, spore-forming Gram-positive rod b. Bacitracin-sensitive, Gram-negative cocci c. Coagulase-negative, Gram-positive cocci d. Nonlactose fermenting, Gram-negative bacilli e. Oxidase-positive, motile, curved, Gram-positive bacilli |
d.
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Which of the following medications, if taken by the man in the above case, could have increased his susceptibility to the infection he developed?
a. Acetaminophen b. Antacids c. β-blockers d. Ibuprofen e. Statins |
b.
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Which of the following bacterial agents has the lowest infective dose for producing gastrointestinal disease in the human host?
a. Enteropathgenic Escherichia coli b. Enterotoxigenic Escherichia coli c. Salmonella (nontyphoid serotypes) d. Shigella flexineri e. Vibrio cholerae |
d.
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Interstitial infection with which of the following organisms should not be treated with antibiotics?
a. Clostridium difficle b. Escherichia coli O157:H7 c. Salmonella typhi d. Shigella sonnei e. Vibrio cholera |
b.
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Fimbriae-mediated adherence to intestinal epithelial cells, type III secretions system-mediated endocytosis and transport to the lamina propria to elicit a localized inflammatory response are descriptive of the infectivity and pathogenesis of which diarrheogenic agent?
a. Campylobacter jejuni b. Clostridium difficile c. Enterotoxigenic Escherichia coli d. Salmonella sp. e. Vibrio cholerae |
d.
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A critically ill patient, who has a Foley catheter, develops a serious UTI, The organism is identified as a motile, nonurease-producing, Gram-negative enteric bacillus with a high degree of antibiotic resistance that rarely causes disease in immune competent people. The agent formed pigments on nutrient agar cultivated at room temperature, as shown in the photograph. What is the etiology of this patient's UTI?
a. Escherichia coli b. Klebsiella pneumoniae c. Psuedomonas aeruginosa d. Proteus mirabilis e. Serratia marcescens |
e.
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A 3-year-old female child presented with a febrile headache, vomitting, and a swollen right knee that was exquisitely painful upon motion. Physical examination revealed a petechial rash on the skin. Gram stain of the synovai fluid revealed the presence of Gram-egative diplococci and culture suggested a strict aerobe that fermented glucose and maltose. Capsule antigens were also detected by serology. Which of the following is most likely the causative agent of thediase?
a. Escherichia coli b. Neisseria meningitidis c. Neisseria gonorrhoeae d. Staphylococcus aureus e. Haemophilus influenzae b |
b.
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An 18-month-old male presents with fever, lethargy, malaise productive coughing, and vomiting. Culture of cerebral spinal fluid samples with Staphylococcus aureus on blood agar reveals the presence of "satellite" colonies. Serology has indicated that the organism is poyribitol phosphate (PRP) positive. Gram stain of the colonies indicates the presence of a Gram-negative coccobacillus. Which one of the following organisms is most likely responsible for the disease?
a. Bordetella pertussis b. Camppylobacter jejuni c. Escherichia coli d. Haemophilus influenzae b e. Pasteurella multocida |
d.
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How could the infection in the above case have been avoided?
a. Improved community sanitation b. Avoidance of infants with similar symptoms c. Avoidnce of day care facilities or other crowded situations d. Use of 10% bleach solution to clean toys shared with other infants e. Vaccination of the infant |
e.
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A 78-year-old man developed endocarditis due to a vancomycin-resistant stain of Enterococcus faecalis. What is the molecular basis of resistance this organism to vancomycin?
a. A change in the terminal pentapeptide from D-ala D-ala to D-ala D-lac b. A mutation in the penicillin-binding protein c. A mutation in the porin protein d. The acquisition of an efflux pump e. The secretion of β-lactamse |
a.
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A 47-year-old woman in India is becoming blind due to repeated infection with Chlamydia trachmoatis. What is seen in the pus draining from her eyes and stationed by immunofluorescence?
a. Elementary bodies b. Inclusion bodies c. Negri bodies d. Gram-negative diplococci d. Gram-positive diplococci |
a.
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A new rapid diagnostic test for strep throat was undergoing clinical trials. Among 500 culture-positive individuals with sore throat, 500 were positive by the test. Among 500 culture-negative individuals, without sore throat, 200 were negative by the test. Describe the sensitivity and specificity of this test?
a. High sensitivity; high specificity b. high sensitivity; low specificity c. Low sensitivity; high specificity e. Low sensitivity; low specificity |
b.
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An 8-year old girl presents to the urgent care facility with 1 day history of fever, sore throat, malaise, and headache. Physical examination reveals a temperature of 39 degrees Celsius, cervical lymphadenopathy, and a whitish tonsilar exudate. A rapid diagnostic test is negative; however, culture of the exudate grew gram-positive cocci in chains that caused β-hemolysis on blood agar. What complication is prevented by appropriate antibiotic therapy for this infection?
a. Bacteremia b. Carditis c. Encephalitis d. Hepatits e. Meningitis |
b.
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What is the basis of serotyping of the pathogen in the above questions?
a. capsular antigens b. cell wall antigens c. flagellar antigens d. O antigens e. M antigens |
e.
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A resident in his first week of outpatient clinic work prescribes erythromycin for the treatment of urinary tract infection, presumably a simple case of Escherichia coli. The attending physician countermands the resident's order and prescribes TMP-SMZ. Why is the therapeutic choice by the attending more appropriate?
a. Bacterial glycocalyx impedes the absorption of erythromycin b. Erythromycin is likely to be inactivated by transpeptidases c. Macrolides are principally secreted in the feces d. Macrolides promote Candida overgrowth in women e. Oral macrocodes are linked to Steven-Johnson syndrome |
c.
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A 10-month-old male child presents with episodes of repetitive coughing with intermittent large gasps of air as well as some vomiting. Parents indicate that the child has been suffering from this condition for about 1 week. Incidentally, the previous week he was reported to have a cold like illness with a fever and sneezing. A white blood cell count shows 65% lymphocytes and 30% neutrophils. An oxidase-positive, Gram-negative coccobaccilus is grown from a nasopharyngeal swab plated on Regan-Lowe charcoal agar. Which one of the following organizes is most likely responsible for this disease?
a. Boratella pertussis b. Corynebacterium diphtheriae c. Haemophilus influenzae d. Mycoplasma pneumoniae e. Streptococcus pneumoniae |
a.
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What are the virulence factors of the organism in the above question that enable it to adhere to and kill ciliated respiratory epithelial cells?
a. Capsular polysaccharide and diphtheria toxin b. M protein and pneumolysin c. Pertactin, filamentous hemagglutinin, and tracheal cytotoxin d. P-pili and lecithinase e. Polyribitol phosphate capsule and colonization factor |
c.
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A 20-year-old male is brought to the emergency department with a 1-day history of delirium. He has had a sustained fever of unto 40 degrees Celsius and a history of progressive headache, myalgia, and constipation which began previously as he was returning to the United States from a trip to visit relatives in India. Physical examination reveals hepatosplenomegaly, diffuse abdominal tenderness, and red spots on the chest and neck. Colonies of a Gram negative bacillus that produced a characteristic fish-eye growth (lactose non-fermentoer with sulfur reduction) are isolated on Hektoen agar from blood and stool samples as shown in the photograph. What is the most likely diagnosis?
a. Cholera b. Hemolytic uremic syndrome c. Shigellosis d. Tularemia e. Typhoid fever |
e.
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A 35-year-old male became ill with watery diarrhea due to a bacterial infection while on a trip to South America. Which of the following is the key event that promotes the development of watery diarrhea?
a. Decrease activity of adenyl cyclase b. Increase in the intestinal epithelial cell levels of cAMP c. Increase in the levels of intracellular chloride d. Movement of water from the intestinal lumen into the epithelial ells e. Movement of ions such as potassium and sodium into the intestinal epithelial cells |
b.
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A 47-year-old male is diagnosed with peptide ulcer disease. Treatment includes antibiotics for infection of the stomach with Helicobacter pylori. Which enzyme is secreted by this organism and enables it to survive in the acid environment of the stomach?
a. Catalase b. Oxidase c. Protease d. Transpeptidase e. Urease |
e.
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A 15-year-old boy presents with diarrhea, malaise, fever, and abdominal pain. The stools were positive for occult blood and fecal leukocytes. Microscopy of the stool also reveals the presence of curved bacilli that moved about on a slide in a darting motion. The etiologic agent, a Gram-negative, curbed rod, grew on specialized medium in microaerophilic conditions. Which of the following organisms is most likely responsible for the disease?
a. Campylobacter jejuni b. Enterotoxigenic Escherichia coli c. Salmonella so. d. Shigella sonnei e. Vibro cholerae |
a.
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A 3-year-old girl develops a wound infection on her hand following a cat bite. Culture of wound exudate on blood agar grew a Gram-negative coccobacillus that is normal flora of that cat oropharnyx. What is the most likely etiologic agent?
a. Bacteroides fragilis b. β-hemolytic streptoccous c. Capnocytophaga canimorsus d. Moraxella catarrhalis e. Pasteurella multocida |
e.
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A 27-year-old male was hospitalized suffering third-degree burns over 50% of this body from a house fire. After 6 days in the hospital, he becomes septic and the burn wounds show tissue necrosis in several areas. Blood and wound cultures grew an oxidase-positive, Gram-negative bacillus resistant to aminopenicilins, macrocodes, and first-generation and second generation cephalosporins. the organism growing on nutrient agar is shown in the photograph. What is the etiology of this man's burn infection?
a. Enterobacter cloacae b. Klebsiella pneumoniae c. Proteus vulgaris d. Pseudomonas aeruginosa e. Serratia marcescens |
d.
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Five adults and seven children in a village in South Africa present over several days to a local clicnic with voluminous watery diarrhea containing flecks of mucus. They show signs of severe dehydration and are treated with oral fluids and electrolytes. Stool cultures grew yellow colonies on thiosulfate citrate bold salt (TCBS) media. What is the etiology of this outbreak?
a. Enteroinvasive Escherichia coli b. Salmonella typhi c. Shigella dysenteriae d. Vibrio cholerae e. Yersina enterocolitica |
d.
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An outbreak of pneumonic plague occurs in the Democratic Republic of the Congo killing over half of the affected individuals. How is this form of plague transmitted?
a. Bite of infected flea b. Direct skin contact with bubos c. Ingestion of contemned water d. Inhalation of aerosolized bacteria e. Introduction of bacteria into wounds while butchering infected animals |
d.
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A 35-year-old man developed a flu-like illness that lasted 3 days and was followed by apparent recovery. Within days, he suffered a recurrent of illness with symptoms of meningitis and oliguria. He was hospitalized and diagnosed with Weil disease? Which of the following organism is the cause?
a. Baronella quintana b. Chlamydia psittaci c. Leptospira interrogans d. Mycobacterium leprae e. Ureaplasma urealyticum |
c
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A 26-year-old man presents with a painless ulcer on the penis from which spiral-shapred bacteria could be visualized on dark-field microscopy. If left untreated, which of the following would be expected to occur within 6 weeks to 6 months?
a. Ataxia b. Dementia c. Disseminated rash d. Kidney failure e. Meningitis |
c.
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A 27-year-old woman presented with a 2-week history of low grade fever, chills, myalgia, headache, and non-productive cough. She was treated with an antibiotic that inhibits cell wall synthesis but did not improve because the causative agent lacks a cell wall. With which organism was she infected?
a. Chlamydophila pneumoniae b. Coxiella burnetti c. Ehrlichia chaffeensis d. Legionella pneumoniae e. Mycoplasma pneumoniae |
e.
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A 24-year-old woman was diagnosed with pelvic inflammatory disease. The infection was found to be polymicrobial and included a Gram-negative anaerobic rod. Identify the most likely anaerobe involved n the infection.
a. Actinomyces israelii b. Bacteroideas fragilis c. Chlamydia trachomatis d. Neisseria gonorrhoeae e. Treponema pallidum |
b.
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A 12-year-old girl develops a low-grade fever, malaise, and tender lymphadenopathy in her right axial area. On her right hand are the scratches she received 10 days previously from her kitten. What is the most likely bacterial cause of this lymphadenopathy?
a. Actinoyces israelii b. Bartonella henselae c. Chlamydia psittaci d. Francisella tularensis e. Yersinia pestis |
b
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A 24-year-old male presented with fever, dry cough, and dyspnea. A sputum sample was induced but it failed to reveal organism on Gram stain. The sputum also failed to grow organisms when cultured on a variety of agars; however, bacteria were isolated in cultured eukaryotic cells. What is the cause of this man's disease?
a. Chlamydophila pneumoniae b. Legionella pneumophila c. Mycobact4erium intracellulare d. Mycobacterium tuberculosis e. Mycoplasma pneumoniae |
a.
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A 23-year-old female is treated for uncomplicated pyelonephritis with an antibiotic that inhibits bacterial DNA gyrase. Which antibiotic did she receive?
a. Ampicillin b. Certriaxone c. Ciprofloxacin d. Gentamicin e. TMP-SMZ |
c
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A 61-year-old dialysis patient develops psuedomonas septicemia for which she is given a β-lactam antibiotic with activity exclusively against aerobic, Gram-negative bacteria. Which antibiotic is she given?
a. Aztreonam b. Certriaxone c. Cephalexin d. Gentamicin e. Imipenem |
a.
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A 67-year-old moderately obese man presents with fever and an erythematous, swollen, tender, warm calf. He is diagnosed clinically with celluitis and catalase-negative, β-hemolytic Gram-positive cocci are isolated from blood cultures. which virulence factor of the causative organism enabled it to cause this invasive disease?
a. An A-B exotoxin b. Lipopolysaccharide c. P fimbrae d. Streptokinase e. Yops proteins |
d.
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A 22-year-old woman is admitted to the hospital with pelvic inflammatory disease. Her empiric antibiotic regime requires coverage for anaerobes. Which antibiotic would provide appropriate anaerobic coverage?
a. Azithromycin b. Ceftriaxone c. Gentamicin d. Linezolid e. Metronidazole |
e
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A 37-year-old male is seen at a sexually transmitted disease clinic for treatment of gonorrhea. Prior treatments for this disease have successfully eradicated the organism; however, the man has not changed his behavior and has been repeatedly reinfected. What is the most important strategy the organism employs which enables it to cause repeated infections?
a. Antigenic variation b. Induction of immune suppression c. Intracellular growth in alveolar macrophages d. Polysacchride capsule e. Secretion of IgG protease |
a.
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A 76-year-old man receiving chemotherapy for cancer developed an abrupt onset of fever, chills, headache, nonproductive cough, and diarrhea. A chest radiograph suggested a diagnosis of pneumonia. The organism , isolated from sputum and blood culture, is an aquatic saprophyte that infects amoebas outside of the body and macrophages following infection. What is this organism?
a. Chlamydia pneumoniae b. legionella pneumophila c. Mycobacterium tuberculosis d. Mycoplasma pneumoniae e. Streptococcus pneumoniae |
b.
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A 7-year-old child develops impetigo involving large areas of his body. He is given an antibiotic that inhibits cell wall synthesis. Which is the most likely antibiotic this child would have received?
a. Ampicillin b. Cephalexin c. Ciprofloxacin d. Clindamycin e. Erythromycin |
b.
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A 64-year-old woman is hospitalized with community-acquired pneumonia. Empiric antibiotic treatment consist of a drug that inhibits bacterial protein synthesis by binding to the 50S subunit of the bacterial ribosome and a β-lactam antibiotic. With which of the following should she be treated?
a. Ampicillin plus gentamicin b. Aizthromycin plus ceftriaxone c. Imipenem plus cilastatin d. Peiperacillin pus tazobactam e. Trimethoprim plus sulfamethoxazole |
b.
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A 34-year-old woman presents with fever, nausea, severe abdominal cramping, and blood diarrhea that was fecal leukocyte-positive. A few days previously, she had eaten undercooked chicken. Of the following, which is the most likely etiologic agent?
a. Campylobacter jejuni b. Clostridium perfringens c. Salmonella typhi d. Shigella dysenteriae e. Yersinia enterocolitica |
a.
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A 48-year-old man has been hospitalized in intensive care for 3 weeks following an automobile accident. He develops a fever due to colonization of an intravenous line with Gram-positive cocci that are catalase positive and coagulase negative. What is the most likely cause of this man's fever?
a. Enterococcus faecalis b. Staphylococcus aureus c. Staphylococcus epidermis d. Streptococcus mutans e. Streptococcus pyogenes |
c.
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What is the major virulence factor of the organism in the preceding case?
a. Biofilm production b. Panton-Valentina leukocidin c. Pyrogenic exotoxin d. Streptokinase e. Vancomycin resistance |
d.
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A 5-year-old girl from an orphanage in Ukraine was about to leave for the United States with her adoptive parents when she developed a fever, sore throat, cough, and malaise. A few days later, she was brought to the emergency room in respiratory distress. Physical examination reveals pronounced, bilateral, cervical lymphadenopathy, inflamed pharyngeal area, and a thick, grayish, leathery exudate on the tonsils as shown in the photograph. Part of the exudate had become loose revealing bleeding of the underlying mucosal tissue. The etiologic agent was isolated on tellurite medium. What virulence factor accounts for the pathogenesis of this infection?
a. Immune evasion following production of IgA protease b. Lipopolysaccharide-induced inflammation c. M protein-mediated resistance to phagocytosis d. Secretion of coagulase to facilitate invasion into mucosa e. Toxin-mediated inhibition of protein synthesis |
e.
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Ten days after the onset of illness, the patient in the preceding case deteriorated and she subsequently died from a complication of her infection. What was the most likely cause of her death?
a. Encephalitis b. Kidney failure c. Myocarditis d. Pneumoniae e. Sepsis |
e.
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Blood and urine cultures are taken from a 73-year-old man hospitalized with suspected Escherichia coli urosepsis. Which culture medium would allow selective growth of Gram-negative enterics while suppressing the growth of Gram-positive bacteria, Haemophilus and Neisseria?
a. Blood agar b. Buffered charcoal-yest-extract agar c. Choclate agar d. MacConkey agar e. Thayer-Martin agar |
d.
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A 3-year-old developed bloody diarrhea after eating a poorly cooked hamburger. A few days later, he was hospitalized with oliguria and hypertension. With which organism is he most likely infected?
a. Clostridium perfringens b. Salmonella typhi c. Enteroinvasive E. Coli d. Shiga toxin-producing E. Coli e. Yersinia enterocolitica |
d.
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