HII SAQs - Micro/Pharm - Week 1
D
A 19-year-old man required surgical repair of a fractured radius following a rollerblading accident. The patient developed redness and a yellowish discharge from the surgical site. A Gram stain of the pus revealed Gram-positive cocci. Colonies isolated from the pus were catalase and coagulase positive. Which of the following is the MOST LIKELY cause of infection? A.) Enterococcus faecalis B.) Streptococcus pyogenes C.) Staphylococcus epidermidis D.) Staphylococcus aureus E.) Haemophilus influenzae
D
A 23-year-old man wrecks his motorcycle running into a highway embankment, suffering multiple injuries including a compound fracture of the lower leg and his wounds are heavily contaminated with soil and gravel. Several hours later he is discovered and transported to the trauma unit. Over the course of the day he develops more swelling and unrelenting, intense pain in the leg. Over the next several hours hemorrhagic blisters and crepitation (palpable subcutaneous gas) advance rapidly up the leg. High dosage penicillin therapy is begun. Gram-positive rods are observed in stained specimens from the lesion. Which of the following enzymatic activities is MOST LIKELY associated with the major toxin involved in this disease process? A.) superantigen B.) ADP-ribosylase C.) adenylate cyclase D.) phospholipase C E.) beta-lactamase
E
A 24-year-old female presents to the emergency room with fever and in shock. She has desquamation on the trunk of the body and palms of the hands and soles of the feet. A Gram-positive coccus which is catalase positive and coagulase positive is isolated from a cervical swab. Which of the following terms BEST DESCRIBES the type of toxin responsible for this clinical syndrome? A.) Adenyl cyclase activator B.) ADP-ribosylating toxin C.) Endotoxin D.) Enterotoxin E.) Superantigen
E
A 24-year-old female presents to your office with burning urination, urgency and frequency. She is sexually active. Urine cultures show catalase-positive, Gram-positive cocci. Which of the following tests performed on one of the resulting bacterial colonies would be MOST USEFUL in diagnosing the cause of this patient's illness? A.) capacity to cause α-hemolysis on blood agar B.) coagulase test C.) DNase test D.) presence of yellow pigmented colonies E.) sensitivity to novobiocin
D
A 26-year-old woman presents with a urinary tract infection. When asked about prior medication, she indicates that she has been taking amoxicillin purchased in Mexico for 10 days, but pain upon urination persists. Gram staining of urine reveals abundant Gram-negative rods. Further tests reveal that the bacterial isolate is an E. coli strain that encodes an extended-spectrum-ß-lactamase. What is the MOST LIKELY mechanism by which this bacterium obtained the gene that encodes this antibiotic resistance factor? A.) specialized transduction B.) generalized transduction C.) transformation D.) conjugation E.) transposition
C
A 28-year-old male intravenous drug user presents with a febrile illness that has lasted 2 weeks. He also complains of chills, weakness, dyspnea, cough, arthralgia, diarrhea, and abdominal pain. On examination, a heart murmur is present, and small, tender nodules are found on the finger and toe pads, along with small hemorrhages on the palms and soles. Three sets of blood cultures are obtained from different veins. While awaiting laboratory confirmation, an empiric antibiotic regimen should primarily be directed at which of the following organisms? A.) Enterococci B.) Pseudomonas aeruginosa C.) Staphylococcus aureus D.) Streptococcus pneumoniae E.) Streptococcus pyogenes
C
A 40-year-old man presents to the ER for treatment of a deep wound on his left leg that he sustained while working at a construction site 2 says ago. Examination reveals a 12-cm, tender, edematous wound that is crepitant upon palpation. Application of pressure to the wound causes an exudate to be released. A Gram stain of the exudate shows Gram-positive rods. The wound is debrided and antibiotic therapy is immediately started. Which of the following methods is the MOST APPROPRIATE to successfully culture the causal organism? A.) incubation anaerobically at 42°C B.) incubation at 30°C with CO2 C.) incubation under strict anaerobic conditions D.) incubation on chocalate agar containing antibiotics E.) incubation on lactose-MacConkey agar
D
A 45-year-old woman receives injections of botulinum toxin into the facial muscles surrounding her eyes to reduce wrinkles. This toxin acts by interfering with which mechanism? A.) action of acetylcholinesterase in primary and secondary synaptic clefts B.) binding of acetylcholine to postsynaptic neurons C.) diffusion of acetylcholine across the synaptic cleft D.) release of acetylcholine into the primary synaptic cleft E.) release of Ca++ into the cytosol of the axon terminal
E
A 59-year-old renal transplant patient is being treated with immunosuppressive drugs to reduce the likelihood of graft rejection and develops an infection while still in the hospital recovering from surgery. The organism responsible for the infection is identified by the microbiology lab as methicillin-sensitive Staphylococcus aureus. Which of the following antibiotics would be the MOST SUITABLE for treating this patient's infection? A.) Benzathine penicillin B.) Ticarcillin C.) Penicillin-G D.) Penicillin-V E.) Oxacillin
B
A 6-month-old infant presents with failure to thrive, progressive muscular weakness, and who is unable to support the weight of his own head. On questioning, the mother states that she typically feeds the baby soy-based formula sweetened with honey. Which of the following organisms is MOST LIKELY to be responsible for the child's presentation? A.) Bordetella pertussis B.) Clostridium botulinum C.) Corynebacterium diphtheriae D.) Enterococcus faecalis E.) Group B streptococcus
E
A 65-year-old woman is hospitalized for treatment of lobar pneumonia. Parenteral cephalosporins produce initial improvement in symptoms. However, on the seventh hospital day, she develops hypotension and her temperature increases to 39.4°C. Blood cultures are obtained, and Klebsiella pneumoniae is isolated from multiple specimens. Results of in vitro susceptibility studies for several antimicrobials using the agar disk diffusion (Kirby-Bauer) technique are shown: Antibiotic Result Ampicillin resistant Cefotetan susceptible Ceftriaxone resistant Ceftazidime resistant Cefpodoxime resistant Piperacillin resistant Piperacillin-tazobactam susceptible Ticarcillin-clavulanate susceptible Imipenem susceptible Which of the following is the MOST LIKELY mechanism of antimicrobial resistance observed in this clinical isolate? A.) active efflux of antibiotic from bacterial cells B.) alteration in penicillin-binding protein C.) changes in outer-membrane protein providing entry of antibiotic into bacteria D.) methylation of bacterial ribosomes E.) production of extended-spectrum b-lactamase
A
A 7-year-old boy presents with a history of diarrhea and vomiting. The child had eaten leftover macaroni and cheese with ham a few hours prior to the onset of symptoms. The mother mentioned that the power to their house was knocked out two nights earlier by a downed tree, but the refrigerator had stayed 'cold enough' that the food was probably still OK to eat. No pathogenic bacteria were cultured from stool samples and from rectal swabs. Which type of molecule is MOST LIKELY responsible for this child's disease? A.) a superantigen B.) a guanylyl cyclase inhibitor C.) a protein synthesis inhibitor D.) a streptokinase E.) a lipopolysaccharide
D
A 8-year old boy steps on a rusty nail while playing with his friends on an old pier. He dangles his feet in the lake to wash the wound, and remains with his friends the rest of the day. Not wanting to get into trouble with his mother (who told him to wear shoes before leaving for the lake), the boy says nothing of the puncture wound. Three days later, his mother brings him to the emergency room and he displays all of the classic symptoms of lockjaw. Examination of his medical records reveals that he received none of the childhood vaccines. Which of the following BEST DESCRIBES the physical form of the agent that entered the boy's foot when he stepped on the nail? A.) a bacterium B.) a conidium C.) a fungus D.) a spore E.) a toxin
A
A bacterial culture is exponentially growing in Luria-Bertani broth, and is currently at a density of 2 x 106 CFU per ml. One bacterium of this species completes a single cycle of cell division every 0.5 hours. How many hours will you have to wait for the bacterial culture to reach a density of 3.2 x 107 CFU per ml? A.) 2 hours B.) 4 hours C.) 6 hours D.) 8 hours E.) 10 hours
C
A bacterium isolated in a research lab was found to produce a toxin that inhibited the release of the neurotransmitters glycine and gamma-aminobutyric acid. Which of the following is the MOST LIKELY route by which an adult would become infected with this microorganism? A.) arthropods B.) sexual contact C.) puncture wound D.) contaminated food E.) inhalation of droplets
A
A culture of skin lesions from a four-year-old female patient with pyoderma (impetigo) shows numerous colonies surrounded by zones of beta hemolysis on a blood agar plate. A Gram-stained smear shows Gram-positive cocci. If you found the catalase test to be negative, which one of the following organisms would you MOST PROBABLY have isolated? A.) Streptococcus pyogenes B.) Staphylococcus aureus C.) Staphylococcus epidermidis D.) Streptococcus pneumoniae E.) viridans Streptococci
C
A neonatologist examined an 18-hour-old baby boy who was born the previous day to a woman who had ruptured membranes and was in labor for 20 hours. The physician diagnosed a septic syndrome and ordered an infectious disease work-up. The microbiology laboratory reported that the CNS culture from the spinal tap and the blood culture were growing aerobic, catalase negative, Gram-positive cocci. Based on the history and culture results, which of the following is the MOST LIKELY etiological agent? A.) Listeria monocytogenes B.) Staphylococcus aureus C.) Streptococcus agalactiae D.) Enterococcus faecalis E.) Escherichia coli
B
A new synthetic antibiotic is being tested for its in vitro activity against Neisseria gonorrhoeae clinical isolates. A representative growth curve shows how the growth pattern of >90% of N. gonorrhoeae isolates changes when the new antibiotic is added to bacterial growth medium. Based on these data, to which drug class might the new antibiotic belong? A.) ß-lactamase inhibitors B.) glycylcyclines C.) aminoglycosides D.) carbapenems E.) cephalosporins
B
A number of biochemical tests may be used to aid in the identification of Gram-positive cocci. The catalase test is used to determine if a bacterial species is capable of which of the following activities? A.) catalyze the coagulation of citrated rabbit plasma B.) catalyze the degradation of hydrogen peroxide C.) catalyze the degradation of phospholipase D.) catalyze the lysis of red blood cells E.) catalyze the lysis of white blood cells
C
A patient slips and falls in a hospital shower, and develops minor abrasions on his right forearm as a result. A nurse cleans the abrasion and applies triple antibiotic cream and a bandage. Which of the following is a bacterial target of the antibiotics in this cream? A.) penicillin-binding protein B.) NAG-NAM subunits C.) undecaprenyl pyrophosphate phosphatase D.) bacterial RNA polymerase E.) bacterial topoisomerase (DNA gyrase)
B
A patient's sputum is tested for the presence of Streptococcus pneumoniae, and the culture results come back negative. This does not rule out a diagnosis of pneumococcal pneumonia because: A.) Pneumococci are primarily isolated from the blood during pneumococcal pneumonia. B.) Sputum cultures are positive in only 50% of pneumococcal pneumonia cases. C.) Pneumococci cannot be differentiated from other -hemolytic bacteria that contaminate sputum. D.) Pneumococci do not grow on routine culture media under aerobic conditions.
D
A toxic substance produced by Clostridium perfringens induces massive hemolysis and tissue necrosis when injected into mice. The lethal effect observed in the experiment correlates with the substance's ability to split: A.) carbohydrates. B.) collagen. C.) hyaluronic acid. D.) phospholipids. E.) plasminogen.
C
Alcohol is commonly used to sterilize surfaces. Which of the following bacterial structures is most sensitive to disruption by alcohol, thus accounting for alcohol's antibacterial properties? A.) bacterial cell wall B.) bacterial DNA C.) bacterial membrane D.) bacterial protein E.) bacterial RNA
C
All cases of scarlet fever are due to infection by strains of Streptococcus pyogenes that produce which of the following proteins? A.) exotoxin A B.) exotoxin B C.) erythrogenic toxin D.) streptolysin E.) streptokinase
B
An 83-year-old woman was diagnosed with infective endocarditis following a lengthy period of low-grade fevers, night sweats, and weight loss. She had an impacted wisdom tooth extracted 3-weeks prior to her illness. She received no antibiotic prophylaxis following the dental procedure despite a history of rheumatic heart disease. A Gram-stain of a blood culture revealed Gram-positive cocci. Which of the following is the MOST LIKELY etiologic agent? A.) Staphylococcus aureus B.) viridans Streptococci C.) Enterococcus faecalis D.) Staphylococcus epidermidis E.) Candida albicans
C
Antibody against which antigen of Streptococcus pyogenes is protective against future infections? A.) The hyaluronic acid capsule B.) The erythrogenic toxin C.) The M protein D.) The A carbohydrate substance E.) Streptolysin O
A
At which anatomic site is Staphylococcus aureus most frequently found among the normal bacterial flora? A.) nose B.) throat C.) hands D.) conjunctiva E.) intestines
B
Below is a generic structure of a class of antibiotics. Which of the following atoms in this drug become covalently bound to a bacterial enzyme resulting in the drug's antibiotic effect? A.) Nitrogen-1 B.) Carbon-2 C.) Nitrogen-3 D.) Carbon-4 E.) Sulfur-5
C
Blood cultures from a patient with endocarditis show the presence of a Gram-positive coccus surrounded by a zone of ß-hemolysis. A small amount of a colony is placed on a slide and mixed with hydrogen peroxide. Gas bubbles emerge from the liquid. The MOST LIKELY organism is: A.) group A Streptococcus. B.) group B Streptococcus. C.) Staphylococcus aureus. D.) Streptococcus pneumoniae. E.) Staphylococcus epidermidis.
C
Diphtheria toxin is produced only by those strains of Corynebacterium diphtheriae that: A.) are glucose fermenters. B.) carry the toxin plasmid. C.) are lysogenic for -prophage. D.) carry transposon 10 E.) carry a pathogenicity island (>100 kb insertion sequence).
C
Discs impregnated with optochin (P discs) are used to selectively inhibit the growth of: A.) Enterococcus faecalis. B.) Streptococcus agalactiae. C.) Streptococcus pneumoniae. D.) Streptococcus pyogenes. E.) viridans Streptococci.
B
For which organism is ingestion of a preformed toxin the primary cause of disease? A.) Vibrio cholerae B.) Clostridium botulinum C.) Shigella dysenteriae D.) Streptococcus pneumoniae E.) Salmonella typhi
D
Ideally, an antibiotic should target a microbial component and/or pathway absent from mammalian cells. By this standard, which of the following antibiotics would be expected to be the most toxic to human cells? A.) bacitracin B.) cephalosporin C.) penicillin D.) spectinomycin E.) vancomycin
D
If the frequency of spontaneous mutation for streptomycin resistance is 10-6 and the frequency of spontaneous mutation for rifampin resistance is 10-8, then the frequency with which a bacterial cell will acquire resistance to both rifampin and streptomycin in the same cell at the same time is: A.) 10-2. B.) 10-6.8. C.) 10-8.6. D.) 10-14. E.) 10-48.
E
In a controlled laboratory setting, spores are formed during which of the following phases of bacterial growth? A.) decline phase B.) exponential phase C.) lag phase D.) log phase E.) stationary phase
C
In tracking down the specific physical location of a gene that codes for beta-lactamase production in a plasmid-free strain of Staphylococcus aureus, some contradictory results were obtained. In some clones, the gene appeared to be in one location on the bacterial chromosome, but in other clones the gene was found in several additional locations on the bacterial chromosome. How can this result best be explained? A.) The cells were lysogenic. B.) The gene was part of an F factor. C.) The gene was part of a transposon. D.) This was an Hfr strain of Staphylococcus aureus. E.) The strain is infected with a prophage.
C
Most bacteria differ from humans cells in that they cannot use pre-formed folate but must synthesize it from p-aminobenzoic acid. This underlies the sensitivity of such bacteria to which of the following antimicrobial agents? A.) imipenem B.) linezolid C.) sulfamethoxazole D.) tetracycline E.) vancomycin
B
Mr. R.P. came to his doctor complaining of left leg pain, redness, tenderness and swelling. Examination revealed a swollen tender thigh with an erythematous rash. Temperature was slightly elevated. A differential count showed elevated WBC count with a predominance of PMNs. Mr. R.P. was admitted to the hospital. Mr. R.P. developed spiking high fevers (103°F), and the erythematous rash began to rapidly spread over this thigh toward his knee and calf. WBCs increased to 20,000 /mm3 with many band forms. A needle aspirate from the leading edge of the rash was submitted for microbiological workup. The bacteria responsible for Mr. R.P.'s symptoms made a variety of spreading factors that aid in the ability to cause such severe fasciitis. Which of the following is the BEST EXAMPLE of a bacterial spreading factor? A.) siderophore B.) hyaluronidase C.) hemolysin D.) leukocidin E.) coagulase
B
One of three blood culture bottles drawn from a patient with unexplained fevers reveals Gram-positive cocci growing in clusters. Which of the following tests would be MOST USEFUL in determining whether this organism is a part of the normal skin flora? A.) ability to break down hydrogen peroxide B.) ability to coagulate rabbit plasma C.) ability to grow in the presence of bacitracin D.) ability to grow in the presence of novobiocin E.) ability to grow in the presence of optochin
B
Oxacillin is in the class of penicillin derivatives engineered in an effort to overcome penicillin resistance among isolates of Staphylococcus aureus. Which other drug is also a member of this class of penicillin derivatives? A.) penicillin V B.) dicloxacillin C.) carbenicillin D.) ampicillin E.) piperacillin
B
Peptidoglycan contains all of the following EXCEPT: A.) glycan polymers containing N-acetyl-glucosamine. B.) O-chain-linked lipopolysaccharide. C.) disaccharides and peptide side chains. D.) crosslinks between peptide groups. E.) glycan polymers containing N-acetyl muramic acid.
D
Quinupristin / dalfopristin combination therapy has the following properties EXCEPT: A.) The combination is synergistic. B.) The combination is bacteriocidal. C.) The combination acts to block nascent peptide exit from the bacterial ribosome. D.) The combination binds to 30S ribosomal subunits to inhibit protein synthesis. E.) The combination is active against many vancomycin-resistant Enterococci.
D
Six hours after a delicious Thanksgiving dinner of barley soup, roast turkey, stuffing, sweet potatoes, green beans, cranberry sauce, and pumpkin pie topped with whipped cream, the Smith family of 4 developed vomiting and diarrhea. Which one of the following organisms is MOST LIKELY to be responsible for the symptoms? A.) Shigella flexneri B.) Campylobacter jejuni C.) Vibrio cholerae D.) Staphylococcus aureus E.) Escherichia coli
B
Skin cultures from a patient with impetigo show the presence of a Gram-positive coccus surrounded by a zone of ß-hemolysis. A small amount of a colony is placed on a slide and mixed with hydrogen peroxide. Gas bubbles DO NOT emerge from the liquid. Which of the following organisms is MOST LIKELY responsible for this patient's condition? A.) Enterococcus faecalis B.) Streptococcus pyogenes C.) Staphylococcus aureus D.) Streptococcus pneumoniae E.) Staphylococcus epidermidis
B
Staphylococcus aureus causes a wide variety of infections, ranging from wound infection to pneumonia. Treatment of these infections with penicillin is often complicated by the: A.) inability of penicillin to penetrate the membrane of S. aureus. B.) production of penicillinase by S. aureus. C.) production of penicillin acetylase by S. aureus. D.) lack of penicillin-binding sites on S. aureus. E.) allergic reaction caused by staphylococcal protein.
C
The pathology of Corynebacterium diphtheriae is primarily due to which of the following? A.) formation of three morphologically distinct colony types - gravis, mitis, intermedius B.) formation of an exudative membrane C.) production of an exotoxin D.) presence of lipopolysaccharide in outer membrane E.) intracellular invasivion
D
The production of lactic acid from glucose: A.) is typical of obligately aerobic bacteria. B.) involves use of pyruvate as a final electron acceptor. C.) yields 10 moles of ATP per mole of glucose used. D.) is an example of anaerobic respiration. E.) yields two moles of CO2 per mole of glucose used.
D
The rationale for giving prophylactic antibiotics at the beginning of a surgical procedure can be thought of as an attempt to prevent the bacteria from entering which of the following growth phases? A.) death phase B.) eclipse phase C.) lag phase D.) log phase E.) stationary phase
D
The virulence of the group A beta-hemolytic streptococci is related to their: A.) ability to establish intracellular infections. B.) production of neural exotoxin. C.) production of coagulase. D.) antiphagocytic M protein. E.) production of -toxin.
D
To which of the following drug classes does an antibiotic with this chemical structure belong? A.) cephalosporins B.) fluoroquinolones C.) macrolides D.) penicillins E.) sulfonamides
A
To which of the following drug classes does an antibiotic with this chemical structure belong? A.) cephalosporins B.) fluoroquinolones C.) macrolides D.) polymyxins E.) tetracyclines
B
To which target must the drug whose chemical structure is shown here bind in order to inhibit bacterial cell growth? A.) N-acetyl muramic acid B.) penicillin-binding protein C.) topoisomerase D.) 30S ribosomal subunit E.) 50S ribosomal subunit
D
Toxic shock syndrome may be caused by which of the following organisms? A.) only Staphylococcus aureus B.) only Streptococcus pyogenes C.) only Clostridium perfringens D.) Staphylococcus aureus or Streptococcus pyogenes E.) Staphylococcus aureus, Streptococcus pyogenes, or Clostridium perfringens
A
What mechanism of action BEST DESCRIBES how drugs with this chemical structure inhibit the growth of susceptible bacteria? A.) inhibits cell wall synthesis B.) inhibits DNA synthesis C.) inhibits protein synthesis D.) inhibits RNA synthesis E.) disrupts cell membranes
D
When Group A streptococcal pharyngitis is not eradicated by penicillin treatment, the failure is MOST LIKELY due to which of the following? A.) Group A streptococci are intrinsically resistant to penicillin B.) Group A streptococci transformed by a plasmid-encoded -lactamase. C.) Group A streptococci transduced by a bacteriophage carrying a -lactamase. D.) Group A streptococci that produce a modified penicillin-binding protein E.) Group A streptococci that produce one or more penicillin efflux pumps
C
Which combination of antibiotics would be expected to synergistically inhibit the growth of bacteria susceptible to both antibiotics? A.) cefotaxime and imipenem B.) erythromycin and amoxicillin C.) gentamicin and penicillin D.) methicillin and penicillin E.) tetracycline and streptogramins
C
Which mechanism of action BEST DESCRIBES how gentamicin inhibits the growth of susceptible bacteria? A.) inhibits cell wall synthesis B.) inhibits DNA synthesis C.) inhibits protein synthesis D.) inhibits RNA synthesis E.) disrupts cell membranes
B
Which mechanism of action BEST DESCRIBES how trimethoprim inhibits the growth of susceptible bacteria? A.) inhibits cell wall synthesis B.) inhibits DNA synthesis C.) inhibits protein synthesis D.) inhibits RNA synthesis E.) disrupts cell membranes
B
Which of the following BEST DESCRIBES the capsule of Streptococcus pneumoniae? A.) a scaffold that supports the outer layer of peptidoglycan B.) an outer layer that renders the bacteria resistant to phagocytosis C.) an endotoxin-rich, outer layer that prevents bacterial lysis D.) a scaffold for motor proteins that drive the bacterial flagella E.) a protein-rich, inner layer that supports the cytoplasmic membrane
D
Which of the following antibiotics does NOT inhibit cell wall synthesis? A.) aztreonam B.) bacitracin C.) cefotaxime D.) clindamycin E.) vancomycin
A
Which of the following bacterial components is the basis of the Lancefield classification of streptococci (Group A, B, C, etc.)? A.) cell wall polysaccharides B.) cell wall proteins C.) capsular polysaccharides D.) pili (fimbriae) E.) cell wall lipoproteins
C
Which of the following bonds in this drug structure would be subject to hydrolysis by a b-lactamase enzyme? A.) bond A B.) bond B C.) bond C D.) bond D E.) bond E
A
Which of the following characteristics is critical for both insertion sequences and transposable elements to function as mobile genetic elements? A.) terminal DNA repeats and a recombinase B.) extrachromosomal genetic elements C.) lytic bacterial viruses D.) lysogenic bacterial viruses E.) resistance to one or more antibiotics
A
Which of the following correctly characterizes penicillin G? A.) It only kills actively growing cells. B.) It acts within the cytoplasm. C.) It inhibits NAG-NAM addition to the ends of growing peptidoglycan polymers. D.) It is equally effective on Gram-positive and Gram-negative bacteria. E.) It blocks the synthesis of new NAG-NAM subunits.
B
Which of the following diseases involves the bacterial protein known as exfoliative toxin? A.) pharyngitis B.) scalded skin syndrome C.) food poisoning D.) rheumatic fever E.) gas gangrene
D
Which of the following do typical eukaryotic and prokaryotic cells share in common? A.) nuclear membrane B.) mitochondria C.) peptidoglycan in cell wall D.) cytoplasmic membrane E.) intron-containing genes
D
Which of the following does NOT correctly associate a bacterial species with a laboratory test important in its identification? A.) Streptococcus pneumoniae: optochin sensitivity B.) Streptococcus pyogenes: bacitracin sensitivity C.) Staphylococcus aureus: coagulase test D.) Group B streptococcus: growth in 6.5% NaCl E.) viridans Streptococci : alpha hemolysis
B
Which of the following drugs achieves its antibiotic effects by inhibiting the synthesis of bacterial DNA? A.) amoxicillin B.) ciprofloxacin C.) erythromycin D.) rapamycin E.) tetracyclines
E
Which of the following enzymes is critical in allowing bacteria to complete Reaction 1? A.) ATPase B.) catalase C.) coagulase D.) hydrogen oxidase E.) superoxide dismutase
B
Which of the following enzymes is critical in allowing bacteria to complete Reaction 2? A.) ATPase B.) catalase C.) coagulase D.) hydrogen oxidase E.) superoxide dismutase
B
Which of the following is MOST LIKELY to cause acute bacterial pharyngitis in an 8-year-old boy? A.) viridans Streptococci B.) Streptococcus pyogenes C.) Staphylococcus agalactiae D.) Streptococcus pneumoniae E.) Staphylococcus aureus
D
Which of the following is NOT an action of β-lactam antibiotics? A.) Inhibition of cross-linking of peptidoglycan chain B.) Irreversible binding to specific bacterial proteins C.) Inhibition of a transpeptidase D.) Inhibition of NAG-NAM biosynthesis E.) Trigger lysis of susceptible organisms
C
Which of the following is NOT true of β-lactamases? A.) They hydrolyze the β-lactam ring in penicillins. B.) They can render bacteria resistant to cefazolin. C.) They lyse bacterial cells by triggering hydrolysis of peptidoglycan. D.) They may be inducible or constitutive enzymes. E.) Their activity may be inhibited by drugs such as clavulanic acid.
E
Which of the following is a feature of Gram-positive bacteria rather than Gram-negative bacteria? A.) Lipid A-containing lipopolysaccharide B.) Lipoprotein in periplasmic space C.) Outer membrane D.) Peptidoglycan in periplasmic space E.) Thick peptidoglycan cell wall
A
Which of the following is a predominant organism of the normal flora of the mouth, and a major cause of tooth decay? A.) viridans Streptococci B.) Lactobacillus species C.) Staphylococcus epidermidis D.) Escherichia coli E.) Bacteroides fragilis
C
Which of the following is a predominant organism of the normal flora of the skin, and is commonly seen as a blood culture contaminant? A.) viridans Streptococci B.) Lactobacillus species C.) Staphylococcus epidermidis D.) Escherichia coli E.) Bacteroides fragilis
E
Which of the following is the most abundant microorganism within the normal flora of the bowels? A.) viridans Streptococci B.) Lactobacillus species C.) Staphylococcus epidermidis D.) Escherichia coli E.) Bacteroides fragilis
B
Which of the following is the most abundant microorganism within the normal flora of the vagina, and serves to increase a woman's resistance to yeast infections? A.) viridans Streptococci B.) Lactobacillus species C.) Staphylococcus epidermidis D.) Escherichia coli E.) Bacteroides fragilis
A
Which of the following is the most important structure related to microbial attachment to cells? A.) fimbriae B.) flagellum C.) lipopolysaccharide D.) peptidoglycan E.) plasmid
B
Which of the following organisms is a cause of toxic shock syndrome? A.) Enterotoxigenic Escherichia coli B.) Staphylococcus aureus C.) Streptococcus mutans D.) Clostridium septicum E.) Clostridium perfringens
B
Which of the following organisms is the MOST COMMON cause of community-acquired meningitis in adults? A.) Neisseria meningitidis B.) Streptococcus pneumoniae C.) viridans Streptococci D.) Staphylococcus aureus E.) Staphylococcus agalactiae
A
Which of the following properties is exploited in clinical testing to distinguish Staphylococcus aureus from Staphylococcus epidermidis? A.) coagulase B.) enterotoxin C.) hyaluronidase D.) exfoliative toxin E.) toxic shock toxin
C
Which of the following statements BEST DESCRIBES MacConkey's agar? A.) an enriched growth medium that contains sheep red blood cells B.) an enrichment medium used for the culture of anaerobes C.) a differential and selective medium D.) a medium that changes color in response to acetyl-methyl carbinol production E.) a medium that selects for the growth of Gram-positive bacteria
C
Which of the following statements MOST ACCURATELY describes Bordetella pertussis? A.) It secretes a superantigen that activates ~10% of all CD4+ T cells. B.) It secretes an exotoxin that functions as a protease and which interferes with neurotransmission. C.) It secretes an AB toxin that ADP-ribosylates a G protein and causes coughing spasms. D.) It secretes a neurotoxin that blocks inhibitory nerve signals and causes intense muscle contractions. E.) It is highly tissue-invasive due to the secretion of collagenase, fibrinogen, and hyaluronidase.
A
Which of the following structures is MOST LIKELY to contain genes for enzymes and antibiotic resistance? A.) plasmid B.) pilus C.) capsule D.) plasma membrane E.) penicillin-binding protein
C
Which of the following terms BEST DESCRIBES how Streptococcus pyogenes acquires the ability to synthesize the toxin that causes scarlet fever? A.) Hfr conjugation B.) plasmid transformation C.) specialized transduction D.) transposition E.) homologous recombination
D
Which of the following terms BEST DESCRIBES how genetic information is directly exchanged between two live bacteria? A.) specialized transduction B.) generalized transduction C.) transformation D.) conjugation E.) transposition
C
Which of the following terms BEST DESCRIBES how genetic information is exchanged between a dead (lysed) bacterium and a live bacterium? A.) specialized transduction B.) generalized transduction C.) transformation D.) conjugation E.) transposition
C
Which of the following terms describes the transfer of a donor bacterial chromosome fragment to a new bacterium via infection with a bacteriophage? A.) conjugation B.) lyophilization C.) transduction D.) transformation E.) transposition
C
Which of the following tests may be used to distinguish Group A streptococci from Group B streptococci? A.) optochin sensitivity B.) hemolysis pattern C.) bacitracin sensitivity D.) coagulase activity E.) catalase activity
A
Which of the following virulence factors are NOT associated with Staphylococcus aureus? A.) lipopolysaccharide B.) coagulase C.) protein A D.) hemolysin E.) enterotoxin
A
Which one of the following statements MOST ACCURATELY describes rheumatic fever? A.) it involves inflammation of the heart, joints, skin, and central nervous system B.) the immune response to a staphylococcal antigen cross-reacts with a human antigen C.) prophylaxis with benzathine penicillin is ineffective D.) it is a complication of group A streptococcal skin disease, but not pharyngitis E.) it is more common in adults than in children
E
Which one of the following virulence factors is LEAST LIKELY to be considered an integral component of the bacterial cell surface? A.) capsule of Klebsiella pneumoniae B.) pili of Escherichia coli C.) flagellum of Proteus vulgaris D.) M protein of Streptococcus pneumoniae E.) siderophore of Staphylococcus aureus
C
Which structural feature of the penicillins and the cephalosporins is responsible for their antibacterial activity and their allergenicity? A.) Sulfur-containing, 5-membered thiazolidine ring B.) Antigenic structure / origin from molds C.) β-lactam ring that serves as a substrate for transpeptidase D.) a para-D-alanine, D-alanine benzyl ring that mimics para-amino butyric acid (PABA) E.) A purine nucleotide analog that competitively inhibits DNA gyrase
E
Which term BEST DESCRIBES the -toxin produced by Clostridium perfringens? A.) an enterotoxin B.) an adenylyl cyclase activator C.) a neurotransmission inhibitor D.) a superantigen E.) a phospholipase
D
Which term BEST DESCRIBES the streptococcal and staphylococcal pyrogenic exotoxins? A.) leukocidins B.) adenylyl cyclase activators C.) neurotransmission inhibitors D.) superantigens E.) phospholipases
D
Which toxin is most frequently associated with the lysogenic conversion of Staphylococcus aureus? A.) hemolysins B.) leukocidins C.) enterotoxins D.) exfolatiative toxin E.) pyrogenic exotoxins
C
Why do the blood levels of penicillin G drop rapidly following a single parenteral dose of the drug? A.) The drug is destroyed by β-lactamase. B.) The drug is inactivated by methylation. C.) The drug is secreted by renal tubules. D.) The drug is metabolized in the liver. E.) The drug is preferentially taken up by fat deposits.
D
You just diagnosed Jack Daniel (age 39) with Pseudomonas septicemia. Which one of the following penicillins should you use to treat this patient? A.) amoxicillin B.) methicillin C.) penicillin V D.) Ticarcillin-clavulanic acid E.) none of the above
