HII SAQs - Micro/Pharm Week 2
B
A 13-year-old girl presents with a high fever of two days duration, and vomiting and diarrhea since yesterday. Physical examination reveals an area of high sensitivity to hand pressure on the lower right abdominal quadrant. Blood analysis shows a high neutrophil count. Upon consultation with a surgeon, it is decided to remove the child's appendix, which was inflamed and enlarged. Sampling of the purulent fluid within reveals numerous Gram-negative large rods as well as Gram-positive cocci (greater than 1,000 organisms per ml), however plating samples aerobically on MacConkey agar reveal only 3 pinkish-red colonies from a 10 ml sample. What are the numerous bacilli observed in the Gram stain preparation that are contributing to the symptoms of this infection? A.) Escherichia coli B.) Bacteroides fragilis C.) Peptostreptococcus magnus D.) Staphylococcus aureus E.) Proteus mirabilis
D
A 20-year-old female was seen in the Student Health Center because of frequent and painful urination. She had been sexually active since the age of 16 . Her urine culture grew >100,000 CFU/ml on a blood agar plate. The isolate was Gram-negative, lactose-positive, and indole-positive. What is your diagnosis? A.) Staphylococcus aureus B.) Proteus mirabilis C.) Staphylococcus epidermidis D.) Escherichia coli E.) Staphylococcus saprophyticus
C
A 21-year-old female came to her physician complaining of a burning sensation upon urination. The urinalysis contained 3+ white cells with many bacteria seen. The urine culture revealed >100,000 colonies of a Gram-positive, catalase-positive, coagulase-negative cocci showing resistance to novobiocin. The etiologic agent of this UTI was: A.) Staphylococcus aureus. B.) Staphylococcus epidermidis. C.) Staphylococcus saprophyticus. D.) Streptococcus pyogenes. E.) Enterococcus faecalis.
C
A 22-year-old male ingests a solution containing 13C-labeled urea. He is then asked to blow into a tube, and the labeled carbon is detected in his breath samples. This test is MOST LIKELY part of the evaluation for which of the following conditions? A.) bronchiectasis B.) chronic hepatitis C.) duodenal ulcer D.) pancreatitis E.) pulmonary fibrosis
A
A 25-year-old male auto accident victim with 3rd-degree burns on his right arm and hand develops a fever, shaking chills, and dropping blood pressure. Careful examination of the finger tips of the burned hand shows a dark-greenish coloration. The same greenish coloration occurs in bacterial colonies isolated from the patient's blood that are growing on a blood agar plate and a MacConkey agar plate. The organism on MacConkey agar was found to be positive for oxidase production. The initial ampicillin/gentamicin therapy has not been successful in reducing the fever and you are awaiting the Mueller-Hinton results to guide you in changing the antibiotic therapy. Based on the data available, which etiologic agent is MOST LIKELY threatening this patient's life? A.) Pseudomonas aeruginosa B.) Proteus mirabilis C.) Escherichia coli D.) Yersinia pestis E.) Staphylococcus aureus
D
A 32-year-old Caucasian male develops profuse watery diarrhea with abdominal cramps, nausea and vomiting during a trip to Mexico. The diarrhea resolved in a couple of days without antibiotic treatment. This patient's symptoms are MOST LIKELY related to: A.) intracellular invasion of enterocytes. B.) production of superoxide dismutase. C.) secretion of a shiga-like toxin. D.) secretion of a cholera-like toxin. E.) the endotoxin present in the bacterial cell wall.
C
A 34-year-old Caucasian female presents to your office with perineal pruritus and vaginal discharge. Her past medical history is significant for acute sinusitis two weeks ago that was treated with ampicillin and clavulanic acid. Pelvic examination shows erythematous vulva and thick adherent, "cottage cheese-like" vaginal discharge. Microscopic examination of the vaginal discharge reveals budding cells. This patient's condition was MOST LIKELY a result of: A.) a decrease in thickness of the vaginal epithelium. B.) an increase in glycogen concentration in the vaginal epithelium. C.) a decrease in number of Gram-negative bacteria in the vagina. D.) an increase in alkaline secretions by the cervical mucosa. E.) a depressed T-lymphocyte response to mucosal stimuli.
E
A 4-year-old boy has experienced diarrhea and abdominal cramps for two days. Fecal samples are cultured on MacConkey agar and reveal a mixture of lactose fermenting and lactose non-fermenting Gram-negative rods. The lactose non-fermenting colonies are capable of producing hydrogen sulfide. Which organism is MOST LIKELY the cause of this patient's diarrhea? A.) Shigella flexneri B.) Vibrio cholerae C.) Enterotoxigenic Escherichia coli (ETEC) D.) Vibrio parahaemolyticus E.) Salmonella enteritidis
E
A 55-year-old man returns from a vacation to the beach. While on vacation, he and his family consumed several meals consisting primarily of seafood, including lobster and raw oysters. Although the other members of his family did not get sick, he developed a bullous rash over his lower extremities, hypotension, and confusion. His past medical history is significant for liver disease and alcoholism. The MOST LIKELY cause of this man's signs and symptoms is: A.) Aspergillus fumigatus. B.) Campylobacter jejuni. C.) Candida albicans. D.) Streptococcus pyogenes. E.) Vibrio vulnificus.
C
A 56-year-old alcoholic male came in with pneumonia. His pneumonia was destructive with extensive necrosis and hemorrhage. His sputum was a brick-red color. Culture revealed a non-motile Gram-negative rod with a capsule, which formed pink colonies on MacConkey agar. The MOST LIKELY organism causing this disease would be: A.) Escherichia coli. B.) Enterobacter cloacae. C.) Klebsiella pneumoniae. D.) Proteus vulgaris. E.) Hemophilus influenzae.
E
A 59-year-old female is brought to the ER with fever skin flushing and an altered level of consciousness. Her blood pressure is 50/20 mmHg, and her pulse is 120 . If blood cultures are positive for Escherichia coli, which of the following bacterial factors is MOST LIKELY responsible for this patient's current condition? A.) capsule B.) shiga-like toxin C.) O antigen D.) heat-labile toxin E.) lipid A
D
A 70-year-old female was admitted to MMC from Heritage Manor Nursing Home with fever, cloudy urine and increasing lethargy for three days. Among other items, physical exam revealed respiration - 37, blood pressure - 110/60 and no rashes. Microbiology lab results of urine culture would usually indicate bacterial infection if the concentration of bacteria in her urine were greater than: A.) 100 bacteria/ml. B.) 1,000 bacteria/ml. C.) 10,000 bacteria/ml. D.) 100,000 bacteria/ml. E.) 1,000,000 bacteria/ml.
D
A 70-year-old woman was admitted to Memorial Medical Center from Heritage Manor Nursing Home with fever, cloudy urine and increasing lethargy for three days. Physical exam revealed respirations - 20 per minute, temperature - 38.5° C, blood pressure - 110/60 mmHg. No rashes were present. Which of the following is the LEAST LIKELY bacterium causing her infection? A.) Escherichia coli B.) Enterobacter species C.) Proteus mirabilis D.) Salmonella typhimurium E.) Klebsiella species
C
A Gram-negative bacterial species secretes an AB-toxin that is largely responsible for the disease symptoms of bloody diarrhea. What is the function of the A subunit of the responsible toxin? A.) activation of adenylate cyclase B.) binding to synaptobrevin C.) inhibition of eukaryotic protein synthesis D.) inhibition of release of -aminobutyric acid and glycine E.) promoting toxin entry into the target cell
E
A Gram-negative bacterial species secretes an AB-toxin that is largely responsible for the disease symptoms of bloody diarrhea. What is the function of the B subunit of the responsible toxin? A.) activation of adenylate cyclase B.) binding to synaptobrevin C.) inhibition of eukaryotic protein synthesis D.) inhibition of release of -aminobutyric acid and glycine E.) promoting toxin entry into the target cell
A
A NYC firefighter is severely burned while rescuing a child from a burning building. While hospitalized in the burn center of your hospital he develops a necrotic, rapidly disseminating bacterial infection in a burn wound. Within hours he becomes agitated and quite confused. By this time his temperature has fallen to 35°C and his blood pressure has fallen considerably. Culture of the infected area and blood cultures yield colonies producing a green pigmentation on the agar. These colonies contain cells that are oxidase positive, Gram-negative rods that can grow at 42°C. Which of the following statements BEST DESCRIBES a property of this organism? A.) These bacteria are among the most antibiotic resistant of medically relevant bacteria. B.) Capsules are the only known virulence factor for these bacteria. C.) Humans are the only known reservoir for these bacteria. D.) These bacteria grow best at 25°C. E.) These bacteria exhibit a special kind of motility called swarming.
A
A Professor of Microbiology travels to Boston to give a talk. Upon arrival, he dines at an eatery known for its ambiance and charm. The following day, while in the midst of his lecture, he experiences the abrupt onset of nausea, cramping abdominal pain, and diarrhea. Using the microscope in his shaving kit, he determined that there were no fecal mononuclear or polymorphonuclear leukocytes present in his stool. Which of the following is the MOST LIKELY cause of this illness? A.) enterotoxigenic Escherichia coli B.) Staphylococcus aureus C.) Yersinia enterocolitica D.) Shigella dysenteriae E.) Salmonella typhi
A
A bacterium is examined and is found to lack superoxide dismutase, catalase, and peroxidase. Which of the following statements BEST DESCRIBES this bacterium? A.) This bacterium is an anaerobe. B.) This bacterium will survive in the presence of O2. C.) This bacterium is more virulent than one containing the three enzymes. D.) This bacterium does not produce superoxide. E.) This bacterium does not produce peroxide.
E
A broad-spectrum antibiotic in the general class of thienamycins is: A.) piperacillin. B.) cefoperazone. C.) ceftriaxone. D.) ciprofloxacin. E.) imipenem.
A
A cancer patient developed nosocomial sepsis and shock due to Pseudomonas aeruginosa. Which of the following is a characteristic of the bacterial product / component responsible for shock? A.) it is pyrogenic B.) it is a superantigen C.) it is inactivated by boiling D.) it is secreted by other related bacteria E.) it induces the immune system to synthesize protective antibodies
D
A developing country is considering the inclusion of the Haemophilus influenzae type b conjugate vaccine into its routine immunization schedule for infants. If effectively implemented, this change in the vaccination schedule would MOST LIKELY affect the epidemiology of which disease in this region? A.) otitis media B.) sinusitis C.) acute bronchitis D.) meningitis E.) conjunctivitis
B
A patient develops antibiotic-associated pseudomembranous colitis in response to drug therapy. Which drug is MOST LIKELY to cause this condition? A.) cefotaxime B.) clindamycin C.) methicillin D.) rifampin E.) vancomycin
D
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. Which of the following was MOST LIKELY responsible for this patient's gastrointestinal symptoms? A.) Escherichia coli B.) Bacteroides fragilis C.) Enterococcus faecalis D.) Clostridium difficile E.) Staphylococcus saprophyticus
B
A patient with a urinary tract infection is receiving a combination of sulfamethoxazole (SMZ) and trimethoprim (TMP). Which statement BEST DESCRIBES the mechanism by which this drug combination inhibits bacterial growth? A.) SMZ destabilizes bacterial cell walls, and thus allows better penetration of TMP. B.) SMZ and TMP inhibit two independent steps in folic acid synthesis. C.) TMP inhibits beta-lactamase activity, and allows SMZ to destabilize bacterial cell walls. D.) SMZ and TMP bind adjacent sites on the ribosome / synergistically inhibit protein synthesis. E.) SMZ and TMP bind topoisomerase II and IV, respectively, and thus inhibit DNA synthesis.
E
A patient with extensive burns developed an infection of the affected skin. A Gram-negative bacillus was isolated that was oxidase-positive and produced a bluish-green pigment on agar plates. This opportunistic pathogen is MOST LIKELY: A.) Klebsiella pneumoniae. B.) Salmonella typhi. C.) Escherichia coli. D.) Proteus vulgaris. E.) Pseudomonas aeruginosa.
D
A stool sample from a patient with acute gastroenteritis contains short rods that are Gram-negative and lactose-negative. Further examination reveals that these organisms are oxidase-negative, motile, and produce H2S. Which of the following is MOST LIKELY to be the organism isolated? A.) Vibrio cholerae B.) Staphylococcus aureus C.) Shigella dysenteriae D.) Salmonella enteritidis E.) Escherichia coli
A
A strain of Proteus mirabilis altered its 30S ribosomal subunit in response to treatment with sub-lethal concentrations of an antibiotic. Which antibiotic would induce such a mutation in this strain? A.) Streptomycin B.) Erythromycin C.) Chloramphenicol D.) Penicillin E.) Vancomycin
A
All of the following statements concerning anaerobic bacteria are correct, EXCEPT: A.) they generate energy by respiration. B.) they grow best in the complete absence of air. C.) they lack superoxide dismutase. D.) they lack catalase. E.) that medically-important anaerobes tend to be aerotolerant.
C
Among the penicillins, which of the following side effects is relatively unique to ticarcillin? A.) acute renal failure B.) asthma and/or bronchoconstriction C.) fever, arthalgia, and lupus-like symptoms D.) hypertension and bleeding E.) selection for Gram-negative bacteria that encode a penicillinase
B
An 8-year-old girl was brought to the Emergency Department of Children's Hospital with bloody diarrhea and thrombotic thrombocytopenia purpura that eventually progressed to hemolytic uremia syndrome. A virulence factor of the MOST LIKELY etiologic agent is: A.) Cholera toxin. B.) Shiga toxin. C.) Heat stable toxin. D.) Vi antigen. E.) Cytotoxin B.
C
An 82-year-old man with a past history of myocardial infarction, pneumonia, hypothroidism, bronchitis, and gout was admitted to the hospital for a workup of fevers of unknown origin. The patient had developed fevers approximately 2 1/2 weeks prior to admission which was associated with a nonproductive cough. The patient has spiking fevers of 101-102° F. He was started on a course of ciprofloxacin followed by azithromycin and finally a course of ofloxacin. Significant improvement in his symptoms after the antimicrobial therapy was not obtained. A dental procedure was done four to five weeks prior to the beginning of his symptoms. Which of the following microorganisms would you expect a blood culture to grow? A.) Staphylococcus aureus B.) Chlamydia pneumoniae C.) Bacteroides species D.) Mycoplasma pneumoniae E.) klebsiella pneumoniae
E
An 87-year-old nursing home resident presented with confusion and fever. In the emergency room, he was found to have a fever of 103°F, blood pressure 100/50, pulse 110/min. Clinical examination revealed a normal chest examination, absence of cough, and an entirely normal abdominal exam. A urine specimen obtained by catheter revealed >100 WBC/field, occasional erythrocytes, and 2+ proteinuria. Gram stain of the urine specimen revealed Gram-positive cocci. Culture is pending. The MOST LIKELY microorganism causing his illness is: A.) Staphylococcus saprophyticus. B.) Escherichia coli. C.) Pseudomonas aeruginosa. D.) Candida albicans. E.) Enterococcus faecalis.
D
An E. coli bacterial isolate exhibits the following antibiotic sensitivity profile: Based on this information, which of the following antibiotic resistance factors is MOST LIKELY expressed by this clinical isolate? A.) D-Ala-D-lactate ligase B.) extended spectrum ß-lactamase C.) multi-drug efflux pump D.) aminoglycoside kinase E.) chloramphenicol acetyltransferase
C
An aspirate from a peritoneal abscess grows two distinct organisms. One is Escherichia coli while the other has the following characteristics: Gram-negative bacillus, obligate anaerobe, resistant to bile salts, and a polysaccharide capsule. The second organism is MOST LIKELY which of the following? A.) Proteus mirabilis B.) Pseudomonas aeruginosa C.) Bacteroides fragilis D.) Salmonella typhi E.) Enterococcus faecalis
B
An outbreak of water-borne gastroenteritis with a high mortality is reported in some Asian countries. It is caused by oxidase-positive, Gram-negative rods that grow well on highly alkaline media. Which of the following patients would MOST LIKELY require the smallest infective dose to initiate the infection? A.) patients who experience recurrent urinary tract infections B.) patients who routinely use antacids C.) patients who routinely use topical steroids D.) patients with peptic ulcer disease E.) patients who have previously had dysentery
A
An outbreak was reported in a day-care center where 60% of the children experienced bloody diarrhea, fever and nausea that lasted 2-6 days. White blood cells and mucus were seen in the stool specimens. An enteric Gram-negative bacillus was isolated from 80% of the stool specimens which was characterized as being lactose-negative, non-gas producing, and non-motile. Which of the following organisms is the MOST LIKELY cause? A.) Shigella sonnei B.) Salmonella enteritidis C.) Bacillus cereus D.) Vibrio cholerae E.) Escherichia coli
A
Broad-spectrum penicillin with antipseudomonas activity is: A.) piperacillin. B.) cefoperazone. C.) ceftriaxone. D.) ciprofloxacin. E.) imipenem.
E
Ceftriaxone treatment would be expected to produce which of the following growth curves? A.) curve A B.) curve B C.) curve C D.) curve D E.) curve E
B
Cefuroxime is believed to exert its antibacterial effect by which of the following mechanisms? A.) competitive inhibition of folate synthesis B.) inhibition of bacterial cell wall synthesis C.) inhibition of DNA gyrase D.) binding to the 30S subunit of bacterial ribosomes E.) binding to the 50S subunit of bacterial ribosomes
B
Cholera toxin effects target cells by which of the following mechanisms? A.) activates endogenous phosphodiesterase B.) activates adenylate cyclase C.) activates guanylate cyclase D.) blocks the fusion of acetylcholine containing vesicles E.) inhibits protein synthesis
D
Diarrhea caused by which one of the following agents is characterized by the presence of fecal polymorphonuclear leukocytes (PMNs)? A.) Salmonella typhi B.) enterotoxigenic Escherichia coli C.) Vibrio cholerae D.) Shigella boydii E.) Salmonella enteritidis
C
E. coli has two major porins located in the outer membrane. What is the function of these porins? A.) stabilization of the mesosome B.) metabolism of phosphorylated intermediates C.) transfer of small molecules through the outer membrane D.) stabilization of the O antigen E.) crosslinking of the peptidoglycan layer
C
Third-generation cephalosporin with good activity against Borrelia burgdorferi is: A.) piperacillin. B.) cefoperazone. C.) ceftriaxone. D.) ciprofloxacin. E.) imipenem.
C
Endotoxin is responsible for many of the effects often seen during an infection by Gram-negative bacteria. Which one of the following is NOT caused by endotoxin? A.) stimulation of cytokine production B.) hypotension and shock C.) watery diarrhea D.) fever E.) activation of complement cascade
B
Endotoxin-mediated symptoms are typically associated with infection by which one of the following organisms? A.) Clostridium perfringens B.) Salmonella cholera-suis C.) Staphylococcus aureus D.) Streptococcus pyogenes E.) Clostridium tetani
B
Five hours after eating fried rice at a restaurant, a 24-year-old woman and her husband both developed nausea, vomiting, and diarrhea. Which of the following organisms is the MOST LIKELY to be involved? A.) Clostridium perfringens B.) Bacillus cereus C.) Salmonella enteritidis D.) Entero-invasive Escherichia coli E.) Shigella sonnei
B
Gram-negative septicemia requires antibiotic sensitivity testing because: A.) too much antibiotic would be ineffective. B.) variations in resistance patterns of bacteria are so common. C.) so few antibiotics are effective. D.) gradually increasing doses are necessary as the bacterial count increases. E.) it is necessary to identify the least expensive antibiotic.
B
If no antibiotics were added, which of the following growth curves would be observed? A.) curve A B.) curve B C.) curve C D.) curve D E.) curve E
E
Iron is essential in bacterial metabolism. When bacteria invade the human host they must capture iron to survive. Which type of macromolecule listed below is MOST IMPORTANT in bacterial iron metabolism? A.) Transferrin B.) Lactoferrin C.) Ferric oxide D.) lipopolysaccharide E.) siderophore
B
Klebsiella pneumoniae exhibits which distinguishing virulence characteristic? A.) abscess formation B.) presence of a capsule C.) a characteristic toxin D.) invasion of the lung epithelium E.) exotoxin
E
Many symptoms associated with shock due to septicemic Gram-negative infections are MOST DIRECTLY attributable to endotoxin's capacity to trigger the overproduction and release of which cytokine? A.) GM-CSF (interleukin-3) B.) interferon- C.) interleukin-2 D.) interleukin-8 E.) tumor necrosis factor-
B
Nosocomial infections are: A.) frequent sequelae of spelunking. B.) acquired in the hospital. C.) infections of the nasal mucosa. D.) readily responsive to common antibiotics. E.) transmitted among family members.
B
Shigella species and E. coli O157:H7 strains both secrete a powerful exotoxin that is virtually identical. How has this virulence factor been exchanged between two different genuses of enteric bacteria? A.) movement of genetic element by a lytic bacteriophage B.) movement of genetic element by a temperate bacteriophage C.) transfer of plasmid DNA between two live bacteria D.) uptake of plasmid DNA by a live bacterium upon the lysis of a donor bacterium E.) movement of genetic element by a transposon
B
Third generation cephalosporin with primary activity against Pseudomonas aeruginosa is: A.) piperacillin. B.) cefoperazone. C.) ceftriaxone. D.) ciprofloxacin. E.) imipenem.
D
Penicillinase isolated from Escherichia coli inactivates 6-aminopenicillinanic acid (diagram below) by breaking which of the following bonds? A.) bond 1 B.) bond 2 C.) bond 3 D.) bond 4 E.) bond 5
C
Pseudomonas aeruginosa is readily distinguished from the Enterobacteriaceae based on which one of the following? A.) Pseudomonas aeruginosa is Gram-positive B.) The Enterobacteriaceae are strict anaerobes C.) Pseudomonas aeruginosa is oxidase-positive D.) Pseudomonas aeruginosa is hemolytic E.) Enterobacteriaceae are straight rods
C
Pyocins are: A.) antibiotics to which Pseudomonas aeruginosa are usually sensitive. B.) bacteriocins produced by Pseudomonas aeruginosa. C.) pigments of Pseudomonas aeruginosa. D.) synthetic anti-pseudomonal drugs. E.) a host defense factor that is not produced in persons with cystic fibrosis.
D
Quinolone antibiotic with broad Gram-negative and Gram-positive activity is: A.) piperacillin. B.) cefoperazone. C.) ceftriaxone. D.) ciprofloxacin. E.) imipenem.
C
Rose-colored spots on the abdomen that blanch on pressure would be consistent with a diagnosis of: A.) cholera. B.) giardiasis. C.) typhoid fever. D.) enterotoxigenic Escherichia coli (ETEC) infection. E.) shigellosis.
E
Salmonella and Shigella can be distinguished from Escherichia coli by: A.) Gram stain and morphology. B.) colonial morphology. C.) smell. D.) amount of fluid loss. E.) lactose fermentation.
C
Sulfonamide treatment would be expected to produce which of the following growth curves? A.) curve A B.) curve B C.) curve C D.) curve D E.) curve E
D
The K, O, and H antigens of the Enterobacteriaceae correspond to: A.) flagellar, somatic, and capsular antigens. B.) somatic, capsular, and flagellar antigens. C.) flagellar, capsular, and somatic antigens. D.) capsular, somatic, and flagellar antigens. E.) capsular, flagellar, and somatic antigens.
D
The MOST LIKELY cause of peritoneal abscess is: A.) Escherichia coli. B.) Bacteroides fragilis. C.) Pseudomonas aeruginosa. D.) co-infection with anaerobes and facultative anaerobes. E.) Enterococcus faecalis.
D
The aminoglycosides are a very active group of antibacterial agents, particularly against Gram-negative bacilli. Identify their mode of action from the list. A.) disruption of cytoplasmic membrane function B.) inhibition of bacterial cell wall synthesis C.) inhibition of bacterial DNA gyrase D.) inhibition of protein synthesis E.) interference with bacterial folic acid metabolism
A
The class of drugs known as quinolones exert their antimicrobial affect by which mechanism of action? A.) inhibition of DNA gyrase B.) inhibition of transpeptidase C.) inhibition of ergosterol synthesis D.) inhibition of reverse transcriptase E.) inhibition of protein synthesis
B
The following vignette applies to the next 2 questions: A 60-year-old man with stroke has been in the hospital for 2 weeks. He starts having fever, chills and respiratory symptoms including cough and sputum production. His CXR showed right lung infiltrates and sputum grew Pseudomonas aeruginosa. 92. Susceptibility test results revealed that this bacterial isolate was a mulitidrug-resistant strain. Which of the following mechanisms is likely to make this bacterium resistant to carbapenems? A.) mutations in topoisomerase B.) hydrolysis by a plasmid-encoded enzyme C.) alteration of the 30S ribosomal subunit D.) chromosomal mecA gene E.) plasmid-borne vanA gene
D
The following vignette applies to the next 2 questions: A 60-year-old man with stroke has been in the hospital for 2 weeks. He starts having fever, chills and respiratory symptoms including cough and sputum production. His CXR showed right lung infiltrates and sputum grew Pseudomonas aeruginosa. 91. Which of the following antibiotics can be used to treat this organism? A.) ceftriaxone B.) ampicillin C.) methicillin D.) ceftazidime E.) tetracycline
D
The following vignette applies to the next 4 questions: The following five growth curves are lettered A - E and each corresponds to an expected growth curve if certain antibiotics were added to an exponentially growing culture of drug-sensitive Escherichia coli. The arrow indicates the time at which antibiotics were added to the growing culture. 73. Chloramphenicol treatment would be expected to produce which of the following growth curves? A.) curve A B.) curve B C.) curve C D.) curve D E.) curve E
C
The formation of colonic ulcers and abscesses during infection with Shigella dysenteriae is due to: A.) the ability of bacteria to survive stomach acidity because of the production of urease. B.) bacterial survival within macrophages. C.) invasion of enterocytes and cell-to-cell spread of the bacteria. D.) bacteremic spread of the organisms. E.) production of heat labile (LT) enterotoxin.
C
The most important protective function of the antibody stimulated by tetanus immunization is that it: A.) opsonizes the pathogen. B.) prevents the growth of the pathogen. C.) neutralizes an exotoxin of the pathogen. D.) prevents adherence of the pathogen. E.) prevents sporulation by the vegetative cell.
D
The only major category of infectious diseases with which Enterobacteriaceae members have not been definitively associated is that of: A.) Urinary tract infections. B.) respiratory tract infections. C.) skin and soft tissue infections. D.) sexually transmitted infections. E.) systemic infections.
B
The specimen showing the highest likelihood of a positive result for bacteria in a person with typhoid fever is: A.) blood. B.) bone marrow. C.) feces. D.) sputum. E.) urine.
A
Volunteer studies are used to determine the infective dose of Salmonella enteritidis required to cause gastroenteritis. The curve obtained during the studies is labeled as '2' on the diagram below. Which of the following organisms would be MOST ACCURATELY represented by '1' on this same diagram? A.) Shigella flexneri B.) Vibrio cholerae C.) Salmonella typhi D.) enterotoxigenic Escherichia coli E.) Clostridium botulinum
E
What is the MOST COMMON source from which humans acquire shigellosis? A.) dogs B.) cats C.) swine D.) chickens E.) humans
B
Which is an UNCOMMON site of anaerobic bacterial infection? A.) gingival crevices B.) cerebrospinal fluid C.) lower abdomen D.) ruptured appendix E.) urogenital tract
D
Which of the following antibiotics attaches to the 50S ribosomal subunit and inhibits polypeptide synthesis? A.) penicillin B.) nalidixic acid C.) amphotericin D.) streptogramin B E.) trimethoprim
A
Which of the following bacteria is MOST commonly associated with the formation of struvite stones accompanying UTI? A.) Proteus mirabilis B.) Escherichia coli C.) Enterococcus species D.) Pseudomonas aeruginosa E.) Staphylococcus saprophyticus
E
Which of the following correctly associates a bacterial species with a laboratory test that is important in its identification? A.) Streptococcus pneumoniae: bacitracin sensitivity B.) Streptococcus pyogenes: alpha hemolysis on blood agar C.) Staphylococcus aureus: beta hemolysis on blood agar D.) Klebsiella pneumoniae: hydrogen sulfide production E.) Enterococcus faecalis: growth in 6.5% NaCl
D
Which of the following diarrhea-causing Escherichia coli strains have been associated with the sequelae of hemolytic uremic syndrome? A.) Enterotoxigenic Escherichia coli B.) Enteroinvasive Escherichia coli C.) Enteropathogenic Escherichia coli D.) Enterohemorrhagic Escherichia coli E.) Enteroadherent Escherichia coli
A
Which of the following drugs is MOST LIKELY to interfere with vitamin K availability, leading to hypoprothrombinemia and possible bleeding disorders? A.) Cefoperazone B.) Procaine penicillin G C.) Imipenem D.) Cefazolin E.) Nafcillin
D
Which of the following infectious agents is the MOST COMMON cause of travelers' diarrhea? A.) Shigella sonnei B.) Enterohemorrhagic Escherichia coli C.) Salmonella species D.) Enterotoxigenic Escherichia coli E.) Staphylococcus aureus
E
Which of the following is a predisposing factor for a urinary tract infection? A.) catheterization B.) prostatic hypertrophy C.) presence of kidney stones D.) being female E.) all of the above
D
Which of the following microorganisms is an obligate aerobe? A.) Bacteroides fragilis B.) Clostridium perfringens C.) Escherichia coli D.) Mycobacterium tuberculosis E.) Pseudomonas aeruginosa
E
Which of the following symptoms is unique to infection with Salmonella typhi and Salmonella choleraesuis that is NOT observed with most enteric pathogens? A.) Bacteremia B.) Mild to severe watery diarrhea C.) Dehydration and electrolyte imbalance D.) Frequent passage of bloody stools E.) Invasion of the intestinal epithelial cells
D
Which of the following terms BEST DESCRIBES the mobile genetic element that confers upon Salmonella species the ability to invade eukaryotic cells? A.) plasmid B.) transposon C.) prophage D.) pathogenicity island E.) insertion sequence
D
Which one of the following Escherichia coli toxins is MOST SIMILAR to the Shiga-toxin of Shigella dysenteriae? A.) heat-labile LT enterotoxin B.) heat-stable ST enterotoxin C.) adherence-promoting toxin D.) verotoxin E.) exfoliative toxin
A
Which one of the following agents has the lowest 50% infective dose (ID50)? A.) Shigella flexneri B.) Vibrio cholerae C.) Salmonella typhi D.) enterotoxigenic Escherichia coli E.) Clostridium perfringens
E
Which one of the following antibiotics inhibits dihydrofolate reductase? A.) piperacillin B.) amdinocillin C.) amphotericin D.) chloramphenicol E.) trimethoprim
D
Which one of the following innate defense mechanisms is the MOST important for preventing diarrheal disease caused by Vibrio cholerae? A.) esophageal mucosa B.) salivary enzymes C.) normal flora of the mouth D.) gastric acid E.) short-chain fatty acids
C
Which one of the following is NOT an invasive organism? A.) Shigella sonnei B.) Salmonella species C.) Enterotoxigenic Escherichia coli D.) Campylobacter jejuni E.) Helicobacter pylori
E
Which one of the following organisms that infect the gastrointestinal tract causes bacteremia most frequently? A.) Vibrio cholerae B.) Shigella flexneri C.) Campylobacter jejuni D.) enterotoxigenic Escherichia coli E.) Salmonella typhi
A
Which strain of Escherichia coli relies on heat-labile (LT) and heat-stable (ST) proteins to cause disease? A.) Enterotoxigenic Escherichia coli B.) Enteroinvasive Escherichia coli C.) Enteropathogenic Escherichia coli D.) Enterohemorrhagic Escherichia coli E.) Enteroadherent Escherichia coli
A
Which term BEST DESCRIBES movement of DNA from one bacterium to another bacterium through a sex pilus? A.) conjugation B.) complementation C.) transposition D.) transformation E.) transduction