Microbiology Question Set 1

A previously healthy 55 year old white male presents with a 7-day history of chills, high-fever, dyspnea, productive cough, pharyngitis, drowsiness and pleuritic chest pain. On physical examination, his temperature is 103 F, pulse 110 bpm, respirations 26 cpm with decreased breath sounds on the right side. A large, tender and palpable node is found in the right axilla. The patient is a farmer with daily contact with rabbits, horses, sheep, pigeons and chickens. He was reportedly cleaning the barn 3 days before the onset of symptoms. No tick bites are noted. Cxr reveal multiple ovoid infiltrates in the lower lobe of the right lung with pleural effusions. Gram stain of sputum and lung lesions reveal no organisms. Serology tests are negative. Based on your findings, what is the most likely causative organism?

A 50 year old male presents with a 4-week history of fevers, chills, fatigue, generalized weakness, drenching night sweats and two episodes of nonbilious emesis. Four weeks before presentation, he had traveled to the Netherlands for four days. Symptoms started a few days after he returned home. Laboratory tests reveal pancytopenia, hemolytic anemia and elevated aminotransaminase; a peripheral blood smear shows basophilic ring-shaped and pear-shaped structures in multiple red cells and shows extracellular basophilic ring forms on Wright-Giemsa staining. Further evaluation revealed parasitemia and a few schistocytes, poikilocytes and merozoites in tetrad formation. The findings are most consistent with which diagnosis?

A 32 y.o pregnant female presents with a 3-day history of cramping abdominal pain, nausea, severe watery diarrhea, fever and malaise. She was started on a 7-day therapy with amoxicillin after being admitted to the hospital for pyelonephritis five days ago. Examination reveals a fever of 102 F, abdominal distention and tenderness. Laboratory tests show a peripheral WBC of 15,000/cumm and stool guaiac positive for occult blood. Based on the findings, what is the appropriate pharmacotherapy?

A previously healthy 23 y.o nurse is evaluated in urgent care for a 6-day history of a progressively worsening headache, photophobia and intermittent fever. Headache is mostly frontal that radiates down the neck. She has no history of blood transfusion, recent travel or contact with animals and can recall only of childhood varicella. There are no risk factors for human immunodeficiency virus. On examination, she appears pale and diaphoretic with a temperature of 101.3 F (38.5 C). Vital signs are stable. A fine erythematous rash is noted on the neck and forearms. Analysis of cerebrospinal fluid reveals: Opening pressure: 30 cm H2O Cell count: 0 erythrocytes 72 leukocytes (10% neutrophils, 75% lymphocytes, 15% mononuclear) Protein 100 mg/dL Glucose 70 mg/dL Based on these findings what is the most likely diagnosis?

A 27 y.o male refugee was admitted due to a 3-week history of fever, malaise, anorexia, weight loss, chest pain on exertion and fatigue. No history of any cardiac disease. He has lived in poor hygienic conditions in overcrowded quarters and close contact with cats for the past two years. The patient was hemodynamically stable upon admission: blood pressure 120/60 mmHg, heart rate 90 bpm, temperature 38 C. Physical examination reveals pallor, an early diastolic murmur on the left 3rd ICS. Lung auscultation is normal and abdominal examination reveals tender and mildly enlarged spleen. Lab exams: WBC 14,500 /μL, 5% bands, 93% PMN. A transthoracic electrocardiogram reveals a 5 mm vegetation on the aortic valve with moderate regurgitation. Three sets of blood culture were taken within 24 hours of admission followed by empirical therapy with gentamicin and vancomycin for possible infective endocarditis. The cultures remain negative for growth five days after. Following a week of empirical therapy, the patient continues to deteriorate. What test should be ordered to confirm the most probable diagnosis?

A 28 y.o white female presents with a 15-day history of malodorous vaginal discharge and pruritus. She reports that the smell is worse after intercourse and is accompanied by a white discharge. She has no significant medical or gynecological history. She is in a stable monogamous relationship and has never been pregnant. Which of the following diagnostic features is consistent with bacterial vaginosis?

A 52 y.o male presents with a 5 week history of multiple ulcerative cutaneous lesions on his left forearm and neck. He first noticed after returning from a 2-month stay in rural Peru. He does not recall of any trauma or arthropod bites. The lesion began as a non-pruritic erythematous papule that became enlarged, ulcerated and crusted. There is no fever and abdominal pain. Physical examination reveals erythematous, crusted plaques with central ulceration and a raised border. There was no fluctuance, drainage or sporotrichoid spread. A punch biopsy was performed and reveals an ulcerated lesion with a mixed inflammatory infiltrate. Amastigotes within dermal macrophages were seen on Giemsa staining. What is the most likely diagnosis?

A previously healthy 40 y.o male presents with a 1-day onset of dizziness, blurred vision, slurred speech and dysphagia. Physical examination revealed right eye ptosis, palatal weakness, impaired gag reflex and paralysis of V and VII cranial nerves. Medical history is unremarkable for diabetes and heart disease. He denied tick exposure and reported to have received the Lyme disease vaccine. Before the onset of symptoms, he had worked outdoors and ate a meal of stew with roast beef and potatoes that had been sitting on the stove for 3 days. What is the mechanism of action of the toxin that is the most likely causative pathogen?

An 18 y.o student from India presents with a 7-week history of nonproductive cough, loss of appetite, fatigue and night sweats. Which of the following investigations can confirm the most likely diagnosis?

A 23 y.o woman with an unremarkable medical history presents for her first prenatal appointment with unusual fatigue and pain in her perineum for the past 8 days. She claims of unprotected intercourse with her husband only. Vaginal exam reveals a clean, ulcerated genital lesion, which is tender and non-exudative. No lymphadenopathy detected. RPR test reveals a titer of 1:64 and the FTA is positive. She reports a past allergic reaction to amoxicillin two years ago. What is the best pharmacotherapeutic management for this patient?