Microbiology+Immunology Test 2

Microbiology+ImmunologyTest 21. Patients with the HLA-B27 antigen are known to have an increased risk of developing certain pathologic con- ditions. Which of the following infectious agents may cause a syndrome characterized by arthritis, conjunc- tivitis, and urethritis in an HLA-B27 positive patient?(A) Borrelia burgdorferi(B) Chlamydia trachomatis(C) Enterotoxigenic Escherichia coli(D) Group A β-hemolytic streptococci(E) Trichomonas vaginalis2. Which of the following is specifically associated with infection with Schistosoma haematobium?(A) Adenocarcinoma of the bladder(B) Adenocarcinoma of the renal pelvis(C) Squamous cell carcinoma of the bladder(D) Transitional cell carcinoma of the bladder(E) Transitional cell carcinoma of the renal pelvis3. A 29-year-old woman diagnosed with AIDS has had a progressive blurring of vision in her right eye. On fun - duscopic examination, a small white opaque lesion is noted on the retina of her right eye. Which of the fol- lowing is the most appropriate therapy for this patient?(A) Acyclovir(B) Amantadine(C) Flucytosine(D) Ganciclovir(E) Zidovudine4. A 45-year-old homeless man has a chronic cough and a cavitary lesion of the lung. His sputum is positive foracid-fast bacilli. Which of the following is the principal form of defense by which the patient's body fights this infection?(A) Antibody-mediated phagocytosis(B) Cell-mediated immunity(C) IgA-mediated hypersensitivity(D) IgE-mediated hypersensitivity(E) Neutrophil ingestion of bacteria5. A 10-year-old girl presents with sore throat and fever. She denies any cough or rhinorrhea. A throat culture grows bacitracin-sensitive bacterial colonies. The infecting organism would be protected from the lytic action of detergents by its(A) keratin-like proteins in the spore coat(B) lipopolysaccharide in the outer membrane(C) peptidoglycan layer(D) periplasmic space(E) Ca2+ chelators 6. A hospitalized patient with dysuria and suprapubicpain is treated with ciprofloxacin. What is the mecha-nism of action of this antibiotic?(A) It inhibits dihydrofolate reductase(B) It inhibits DNA-dependent RNA polymerase(C) It inhibits protein synthesis by binding to the 30sribosomal subunit(D) It inhibits protein synthesis by binding to the 50sribosomal subunit(E) It inhibits topoisomerase II (DNA gyrase)7. Two weeks after returning from a trip to New Delhi, India, a 35-year-old man presents to the emergency department complaining of daily fevers, headache,chills, and malaise. He recalls getting a number of fleabites on his ankles and calves during his trip. Physical examination reveals a maculopapular rash on his trunk, arms, and thighs. Which of the following is the mostlikely cause of this patient's condition?(A) Bartonella henselae(B) Borrelia recurrentis(C) Coxiella burnetii(D) Ehrlichia chaffeensis(E) Rickettsia typhi8. A child in a developing country develops repeated eye infections with an organists that causes chronic con- junctivitis, scarring, eyelid deformities, pannus forma- tion, and eventual blindness. Which of the following isa distinctive feature of the causative organism?(A) Also causes cat scratch fever(B) Antigen cross-reactivity with antibodies to Proteusvulgaris(C) Arthropod transmission(D) Bird reservoir(E) Reticulate body9. A 34-year-old woman presents with fatigue, malaise, and swollen, tender joints. Physical examination is significantfor a maculopapular eruption over sun-exposed areas, including the face. Examination of a peripheral blood smear reveals mild thrombocytopenia. Which of the fol- lowing autoantibodies, if present, would be most specif-ic for the diagnosis of the patient's disorder?(A) Anti-centromere antibody(B) Anti-IgG antibody(C) Antinuclear antibody(D) Anti-Sm (Smith antigen) antibody(E) Anti-SS-A (Ro) antibody10. A 4-year-old girl presents with a maculopapular rash on her hands and feet and painful ulcers distributed ante-riorly on her lips, palate, tongue, and buccal mucosa. Systemic features and lymphadenopathy are absent.Which of the following viruses is most likely to have caused this disorder?(A) Coronavirus(B) Coxsackievirus type A16(C) Herpes simplex virus type 1(D) Parainfluenza type 3(E) Rhinovirus11. A patient with nuchal rigidity and headache undergoes lumbar puncture. The CSF contains markedly increased numbers of lymphocytes, leading to a pre- sumptive diagnosis of viral meningitis. Which of the following groups of viruses is most likely to beinvolved?(A) Adenoviruses(B) Enteroviruses(C) Human papillomaviruses(D) Poxviruses(E) Reoviruses12. While playing outside, an 8-year-old girl is bitten in the leg by a neighbor's cat. She presents the next day withfever and bone pain localized to her right calf. An x-rayfilm reveals a lytic lesion of the right tibia. Results of the bone culture are pending. Which of the following is the most likely pathogen?(A) Brucella melitensis(B) Eikenella corrodens(C) Francisella tularensis(D) Pasteurella multocida(E) Yersinia pestis13. A 6-year-old boy presents to the pediatric clinic with fever and earache. He has just finished an unsuccessful course of amoxicillin. On physical examination, hisright tympanic membrane appears injected. Which ofthe following is the most appropriate pharmacotherapy?(A) Amphotericin B(B) Bacitracin(C) Cefaclor(D) Erythromycin(E) Sulfamethoxazole14. A 4-year-old boy presents to the emergency department with muscle spasms. His past medical history is signifi- cant for recurrent infections and neonatal seizures. Evaluation of his serum electrolytes reveals hypocal- cemia. This patient would be most susceptible to whichof the following diseases?(A) Chickenpox(B) Diphtheria(C) Gas gangrene(D) Gonorrhea(E) Tetanus 15. A patient develops fever and shortness of breath, and appears to be quite ill. An x-ray film demonstrates bilat- eral interstitial lung infiltrates, and bronchial washings demonstrate small "hat-shaped" organisms visible on sil- ver stain within the foamy alveolar exudate. Which pre- disposing condition is most likely present in this patient?(A) AIDS(B) Congestive heart failure(C) Pulmonary embolus(D) Rheumatoid arthritis(E) Systemic lupus erythematosus16. A 30-year-old veterinarian visits her obstetrician for a first-trimester prenatal check-up. She has no com- plaints. Routine physical examination is significant only for mild cervical lymphadenopathy. She is prescribed spiramycin but is noncompliant. Her child is born with hydrocephalus and cerebral calcifications. Which of the following organisms is most likely responsible?(A) Isospora belli(B) Leishmania donovani(C) Plasmodium vivax(D) Toxoplasma gondii(E) Trypanosoma cruzi17. A 38-year-old woman complains of cold and painful fingertips, as well as difficulty swallowing and indiges- tion. Physical examination is remarkable for a thick- ened, shiny epidermis over the entire body, with restricted movement of the extremities, particularly the fingers, which appear claw-like. Which of the following autoantihodies will likely be found in this patient's serum?(A) Anti-DNA topoisomerase I (anti-Scl-70)(B) Anti-double-stranded DNA (ds DNA)(C) Anti-IgG(D) Anti-Sm(E) Anti-SS-A18. A 24-year-old AIDS patient develops chronic abdominal pain, low-grade fever, diarrhea, and malabsorption. Oocysts are demonstrated in the stool. Which of the fol- lowing organisms is most likely the cause of the patient's diarrhea?(A) Diphyllobothrium latum(B) Entamoeba histolytica(C) Giardia lamblia(D) Isospora belli(E) Microsporidia19. An African child develops massive unilateral enlarge- ment of his lower face in the vicinity of the mandible. Biopsy demonstrates sheets of medium-sized blast cells with admixed larger macrophages. This type of tumorhas been associated with which of the following?(A) Epstein-Barr virus and t(8;14)(B) Hepatitis B and t(9;22)(C) Herpesvirus and CD5(D) HIV and CD4(E) Human papillomavirus and t(2;5)20. A 1-week-old girl with symptoms of vomiting and anorexia has a temperature of 102 F. A bulging fontanelis noted on physical examination. Which of the follow-ing is the most likely causative agent?(A) Haemophilus influenzae type b(B) Listeria monocytogerus(C) Neisseria meningitidis(D) Staphylococcus aureus(E) Streptococcus agalactiae21. A mailman gets a severe bite wound from a pit bull guarding a junkyard. The wound is cleansed and he receives a booster injection of tetanus toxoid and an injection of penicillin G. Several days later, the woundis inflamed and purulent. The exudate is cultured onblood agar and yields gram-negative rods. Antibiotic sensitivity tests are pending. Which of the following isthe most likely pathogen?(A) Bartonclla henselae(B) Brucella canis(C) Clostridiuim tetani(D) Pasteurella multocida(E) Toxocara canis22. A 1-year-old girl presents with a 2-day history of fever, vomiting, and watery, nonbloody diarrhea. On physical examination, she appears dehydrated. Which of the fol- lowing best describes the most likely infecting organism?(A) It has a complex double-stranded DNA genome(B) It has a partially double-stranded circular DNAgenome(C) It has a segmented, double-stranded RNA genome(D) It has a single-stranded circular RNA genome(E) It has a single-stranded RNA genome23. What is the treatment of choice for an infection with Cryptococcus neoformans?(A) Amphotericin B(B) Isoniazid(C) Ketoconazole(D) Metronidazole(E) Nystatin24. A 27-year-old, HIV-positive patient presents complain- ing of visual disturbances. The patient is referred to an ophthalmologist, who notes perivascular hemorrhageand bilateral retinal exudates. The virus responsible forthis patient's retinitis belongs to which of the following viral families?(A) Adenovirus(B) Herpesvirus(C) Orthomyxovirus(D) Paramyxovirus(E) Retrovirus25. A 78-year-old woman with a history of renal calculi and recurrent urinary tract infections presents with fever, chills, leukocytosis, and cloudy urine that has a pH of 8.2.A urine culture grows a lactose-negative, urease-positive, gram-negative rod. Which of the following microorgan- isms is most likely responsible for her infection?(A) Candida albicans(B) Enterococcus faecalis(C) Escherichia coli(D) Klebsiella pneumoniae(E) Proteus mirabilis(F) Pseudomonas aeruginosa(G) Staphylococcus saprophyticus26. A 25-year-old woman presents with pain and tenosyn- ovitis of die wrists and ankles, and arthralgias of other joints. She notes two prior episodes similar to the pre-sent one. She just had her menstrual period during the previous week. Physical examination reveals ulcerated lesions overlying the wrists and ankles. These symptoms are likely due to deficiency of which of the following?(A) Cl esterase inhibitor(B) Ciliary function(C) Complement (C6-C8) components(D) Endothelial adhesion molecules(E) Eosinophils27. An 8-month-old infant presents to the emergency department with a 1-day history of poor feeding and generalized weakness. The mother states that she often feeds the infant honey to pacify her. The toxin respon-sible for this presentation works by which of the fol- lowing mechanisms?(A) It blocks the release of acetylcholine from thenerve terminal(B) It blocks the release of inhibitory neurotransmit-ters such as glycine and GABA(C) It has a subunit that inactivates an elongation fac-tor by ADP- ribosylation(D) It is a lecithinase(E) It stimulates guanylate cyclase28. A 36-year-old, HIV-positive, white man presents with a fever and progressive headache. He complains of recent forgetfulness and "spells," during which he smells a "harsh, bitter smell." An MRI of the brain shows multi- ple, spherical, ring-enhancing lesions in the left tempo-ral lobe. Laboratory analysis of CSF is normal. Which of the following microorganisms is most likely responsiblefor his illness?(A) Coxsackievirus(B) Cryptococcus neoformans(C) Cytomegalovirus(D) Diphyllobothrium latum(E) Herpes simplex virus(F) Mycobacterium leprae(G) Pasteurella multocida(H) Pneumocysris carinii(I) Taenia solium(J) Toxoplasma gondii29. A 57-year-old woman with a history of hypertension and arthritis is referred to a rheumatologist for evalua- tion. A complete blood count (CBC) is normal, and amini-chem panel shows no electrolyte abnormalities.Her erythrocyte sedimentation rate (ESR) is elevated,and an antinuclear antibody test (ANA) is positive. Further antibody studies are performed, and the resultsare shown below.Anti-histones high titerAnti-double-stranded DNA not detectedAnti-single-stranded DNA not detectedAnti-SSA not detectedAnti-SSB not detectedAnti-SCI-70 not detectedAnti-Smith not detectedAnti-centromere not detectedAnti-RNP not detected Which of the following diseases is suggested by these results?(A) CREST syndrome(B) Diffuse form of scleroderma(C) Drug-induced lupus(D) Sjogren syndrome(E) Systemic lupus erythematosus (SLE)30. An otherwise healthy patient who wears contact lenses develops a small ulceration of the eye. Which of the fol- lowing organisms is most likely involved?(A) Acanthamoeba(B) Cytomegalovirus(C) Herpes simplex(D) Toxocara(E) Toxoplasma31. A 32-year-old woman with increased frequency of uri- nation, suprapubic pain, and dysuria for the past 3 days comes to the emergency department. She has no fever, nausea, or vomiting. A Gram stain reveals gram-nega-tive rods. Which of the following is the roost likely pathogen?(A) Escherichia coli(B) Neisseria gonorrhoeae(C) Shigella dysenteriae(D) Streptococcus pneumoniae(E) Treponema pallidum32. Gram stain of the sputurn from a patient with lobar pneumonia involving the left lower lobe demonstrates gram-positive, encapsulated, lancet-shaped diplococci. Which of the following is the most probable causative organism?(A) Haemophilus influenzae(B) Neisseria gonorrhoeae(C) Pneumocystis carinii(D) Staphylococcus aureus(E) Streptococcus pneumoniae33. A 12-year-old girl has a temperature of 102.5 F and a sore throat. Two days later, she develops a diffuse ery- thematous rash and is taken to her pediatrician. On physical examination, there is circumoral pallor, and an erythematous rash with areas of desquamation is noted. The myocardial damage that can follow this infection is produced in a manner similar to the dam-age associated with which of the following disorders?(A) Atopic allergy(B) Contact dermatitis(C) Graft-vs-host disease(D) Graves disease(E) Idiopathic thrombocytopenic purpura(F) Myasthenia gravis(G) Rheumatoid arthritis(H) Serum sickness(I) Systemic lupus erythematosus34. A 27-year-old IV drug user presents with difficulty swallowing. Examination of the oropharynx reveals white plaques along the tongue and the oral mucosa. Which of the following best describes the microscopic appearance of the microorganism responsible for this patient's illness?(A) Budding yeast and pseudohyphae(B) Encapsulated yeast(C) Mold with nonseptatc hyphae(D) Mold with septate hyphae35. A 40-year-old, otherwise healthy gardener presents with several subcutaneous nodules on his right hand, where he had cut himself on rose thorns. Physical examination reveals several erythematous fluctuant lesions. Which of the following organisms is most like-ly responsible for his condition?(A) Aspergillus(B) Malassezia(C) Onchocerca(D) Rhizopus(E) Sporothrix36. An alcoholic is brought to the emergency department in respiratory distress. A chest x-ray film demonstrates lobar consolidation of the right lower lung. Which of the fol- lowing organisms should be highest on the differential diagnosis?(A) Klebsiella pneumoniae(B) Legionella spp.(C) Mycoplasma pneumoniae(D) Pneumocystic carinii(E) Staphylococcus aureus37. A diabetic patient has chronic sinusitis that has not responded to a 6-week course of antibiotics. The physi-cian should suspect infection with which of the follow-ing organisms?(A) Actinomyces(B) Aspergillus(C) Cryptococcus(D) Mucor(E) Pneumocystis38. A mother brings her 3-year-old boy into the emergency department because he has developed a harsh, "bark- ing" cough with hoarseness. The virus responsible forthis child's illness belongs to which of the following families?(A) Papovavirus(B) Paramyxovirus(C) Parvovirus(D) Picornavirus(E) Poxvirus39. A 12-year-old boy with sickle cell disease develops sud- den onset of fever and chills accompanied by intensepain and tenderness over the distal tibia. X-ray filmsand CT scan of the distal leg reveal swelling of the sub- cutaneous tissue and bone demineralization. A clinical diagnosis of acute osteomyelitis is made. Blood cultures and bone biopsy are arranged to confirm the diagnosisand isolate the offending agent. Which of the following infectious agents will most likely be identified?(A) Group B streptococci(B) Hemophilus influenzae(C) Mycobacterium tuberculosis(D) Pseudomonas aeruginosa(E) Staphylococcus aureus40. A 53-year-old woman with diarrhea and lower abdom- inal pain of 3 days' duration comes to her physicianafter various home remedies fail to relieve her symp- toms. She denies any recent travel. There is blood andpus in her stool. Fecal cultures yield several flagellated, curved, oxidase-positive, gram-negative rods. Which ofthe following is the most likely pathogen?(A) Campylobacter jejuni(B) Escherichia coli(C) Salmonella(D) Shigella(E) Vibrio cholerae41. A 15-year-old high school student and several of her friends ate lunch at a local Chinese restaurant. They all were served the daily luncheon special, which consistedof sweet and sour pork with vegetables and fried rice.All of the girls developed nausea, vomiting, abdominal pain, and diarrhea within 4 hours of eating lunch.Which of the following is the most likely cause of these symptoms?(A) Bacillus cereus(B) Clostridium botulinum(C) Clostridium perfringens(D) EHEC (Enterohemorrhagic Escherichia coli)(E) Staphylococcus aureus(F) Vibrio cholerae42. Three months after a needle-stick exposure to blood from a patient with hepatitis B, a nurse is evaluated for infection with the virus. Laboratory results reveal:HBsAg absentanti-HBs antibody absentIgM anti-HBc presentIgG anti-HBc absentHBeAg absentOn the basis of these results, which of the followingmost accurately describes the nurse's hepatitis B status? (A) She had been effectively vaccinated against hepati-tis B before the needle-stick exposure occurred(B) She has mounted an inappropriate antibodyresponse to hepatitis B as a result of an immuno-compromised state(C) She is a carrier of hepatitis B(D) She is actively infected with hepatitis B(E) She was not infected with hepatitis B43. A 32-year-old physician who has spent the past several years in New Guinea presents with ulcerating granulo- mata of his genital skin. Microscopic evaluation of the papules with Wright-Giemsa stain reveals l- to 2-μm, rounded structures contained within cystic areas of the cytoplasm of macrophages. Which of the following isthe most likely pathogen?(A) Calymmatobacterium donovani(B) Chlamydia trachomatis(C) Haemophilus ducreyi(D) Human papillomavirus(E) Neisseria gonorrhoeae(F) Treponema pallidum44. Infection with which of the following agents is particu- larly dangerous for patients with anemia?(A) Adenovirus(B) Cytomegalovirus(C) Herpes simplex virus(D) Measles virus(E) Parvovirus45. A previously healthy 11-year-old girl develops a gas- trointestinal infection with cramping and watery stools. After several days, she begins to pass blood per rectumand is hospitalized for dehydration. In the hospital, shehas decreasing urine output with rising blood urea nitrogen (BUN). Total blood count reveals anemia and thrombocytopenia, and the peripheral smear is remark-able for fragmented red cells (schistocytes). Infectionwith which of the following bacterial genera is mostlikely responsible for this syndrome?(A) Campylobacter(B) Clostridium(C) Salmonella(D) Shigelia(E) Vibrio46. An 18-year-old college student presents to the student health center complaining of a sore throat and fever. He describes feeling tired for the past few days and reportsa loss of appetite. On examination, he has pharyngitiswith cervical lymphadenopathy. Blood tests reveal lym- phocytosis and the presence of heterophile antibodies. Which of the following best describes the virus respon- sible for his illness?(A) Double-stranded, enveloped DNA virus(B) Double-stranded, nonenveloped DNA virus(C) Single-stranded, enveloped RNA virus(D) Single-stranded, nonenvdoped DNA virus(E) Single-stranded, nonenveloped RNA virus47. A 35-year-old, sexually active man presents to his internist with a painless penile vesicle. Physical exami- nation reveals inguinal lymphadenopathy. The infect-ing organism is definitively diagnosed and is known to exist in distinct extracellular and intracellular forms. Which of the following is the most likely pathogen?(A) Calymmatobacterium granulomatis(B) Chlamydia trachomatis(C) Haemophilus ducreyi(D) Neisseria gonorrhoeae(E) Treponema pallidum 48. A 47-year-old grocer complains of diarrhea and painful arthritis. Physical examination is remarkable for lym- phadenopathy and weight loss. Biopsy of his smallbowel reveals PAS-positive macrophages within the lamina propria. Electron microscopic examination ofthe macrophages reveals small, rod-shaped structures. Which of the following is the most likely pathogen?(A) Clostridium difficile(B) Enterotoxigenic Escherichia coli(C) Isospora belli(D) Salmonella sp.(E) Tropheryma whippelii49. A 38-year-old AIDS patient presents to the clinic com- plaining of nausea, occasional vomiting, and "bumps"on his groin. On physical exam, the bumps are non- tender, pedunculated, reddish-purple nodules in the inguinal and perirectal areas. His liver is palpable 8 cm below the right costal margin. Routine laboratory testsare remarkable only for slightly elevated aminotrans- ferases and alkaline phosphatase levels. He has two pet cats and denies any foreign travel. Which of the follow-ing agents is the most likely cause of this patient's infec- tion?(A) Bartonella henselae(B) Human papillomavirus(C) Molluscum contagiosum(D) Rickettsia prowazekii(E) Treponema pallidum50. A diabetic patient has chronic sinusitis, which is even- tually treated by evacuation of the contents of the max- illary and ethmoid sinuses. Mucor species are foundwhen the material is examined histologically. The pathologist should notify the clinician immediately because Mucor can cause a virulent(A) meningitis(B) pneumonia(C) septicemia(D) skin infection(E) urinary tract infection。