Microbiology Question Set 2

A 65-year-old woman presents to the emergency room after sustaining a lacerated wound on her right leg after falling in the garden. The wound is dirty. She can't recall when she received her last tetanus vaccine. Which is the best management for this patient?

A 36-year-old woman presents to the emergency center with a 2-day history of right eye inflammation, photophobia and decreased vision. She denied history of trauma. She wears contact lenses and thought that they may be the cause of her symptoms, although she has always used them hygienically. A fluorescein staining shows a corneal dendritic branching ulcer with terminal bulbs that stain with rose-bengal. Giemsa staining shows multinucleated giant cells. What is the most likely causative agent?

A previously healthy 6-year-old girl presents with a 3-day history of malaise and low-grade fever. In the last 24 hours, she has complained about soreness and pain in her mouth and has developed vesicles on her hands and feet. Physical examination reveals several erythematous macules on the oropharynx and small oval vesicles with an erythematous base on the palms. What is the best management for this patient?

A 28-year-old male presents with complaints of malaise, anorexia and vomiting. Physical examination reveals slightly enlarged and tender liver. His urine is dark. No edema or spider angiomata noted. Laboratory tests show the following: HBsAg positive, IgM anti-HBc <1:1000, anti-HBs negative, HBeAg positive, HBeAg antibodies negative, HBV DNA of 2.65 × 109 IU/L and AFP of 125 ng/mL. What is the most likely diagnosis?

A 22-year-old student presents with a 1-week history of fever, sore throat, nausea and fatigue. He could hardly get out of bed the morning of presentation. There are no pets at home and he reports recent unprotected sex. On physical examination, he is febrile and has bilateral posterior cervical adenopathy, exudative pharyngitis with soft palate petechiae and erythematous macular rash on the trunk and arms; mild hepatosplenomegaly. What is the most likely diagnosis?

A 14-month-old child is brought to the clinic for evaluation of a rash. Initially, the rash started on the face and spread to the trunk. He also had fever and cough for the past two days. Examination of the boy reveals a maculopapular rash on the face, trunk, and proximal limbs with no lymphadenopathy. Bluish white spots are noted on oral mucosa and there is mild conjunctival injection bilaterally. His mother tells that they immigrated recently from Asia and is unable to provide details of vaccination of the child. The causative agent for this illness belongs to which of the following viral families?

A 14-year-old girl is rushed to the ER by her parents because of a high-grade fever that started this morning. She vomited several times last night. She constantly complains of a severe headache. On examination, her temperature is 102F, respirations are 20/min, pulse is 112/min, and Blood pressure is 105/78 mmHg. She is highly sensitive to light. Her neck feels stiff on passive flexion. There is a non-blanching maculopapular rash all over the body. CSF samples are sent to the lab for analysis and she is started on intravenous fluids and antibiotics. The CSF analysis will most likely reveal which of the following?

A 43-year-old male comes to the clinic for routine follow-up. He was diagnosed with Hepatitis B several months ago. He does not have any complaints about his health except for some anorexia. General physical examination of the patient is normal. His lab investigation reveals mildly elevated aminotransferases. Which of the following findings indicates that the patient has developed a chronic form of his viral infection?

A 71-year-old female presents with high-grade fever with chills, difficulty in breathing, and productive cough containing rust-colored sputum. She complains of sharp left-sided chest pain. Physical examination reveals increased fremitus, dullness to percussion, and bronchial breath sounds on the lower left side. Chest x-ray shows left lower lobe consolidation. The offending organism from it was cultured was catalase-negative and had a positive quelling reaction. Gram staining of the organism will show:

An 80-year-old woman presents with general malaise and low-grade fever. Physical examination reveals Roth’s spots, Janeway lesions, Osler’s nodes and splinter hemorrhages under her fingernails. Echocardiogram shows vegetations on the mitral valve. Blood culture indicates gram + bacteria which are catalase-negative and able to grow in 40% bile; however, not in 6.5% NaCl. Following the results, the doctor is concerned that the patient may also be possibly suffering from one of the following medical conditions:

A 12-year-old boy presents with stiff jaw and difficulty in swallowing. He also develops painful body spasms triggered by loud noise, light, and physical touch. His father says that a few days ago, his son continued to play football even after falling to the ground and bruising his arms and knee. On examination, he sustains a facial smile, stiff arched back, and clamped hands. The infective toxin responsible for these clinical manifestations travels retrogradely in axons of peripheral motor neurons, and blocks the release of which of the following?

A young immigrant girl presents with low-grade fever, sore throat, painful swallowing, and breathing difficulties. Her voice is unusually nasal, and her swollen neck has a "bull's neck" appearance. On examination, there is a large gray membrane on the oropharynx. Removal of the membrane reveals a bleeding edematous mucosa. Culture on potassium tellurite medium reveals several black colonies. What is the mechanism of action of the bacterial toxin responsible for this condition?

A group of friends went to fast-food restaurant for a college reunion party. Within the next few days, all of them complained of bloody diarrhea, fatigue, and confusion. Physical exam revealed neurological deficits. Laboratory tests show anemia, thrombocytopenia, and uremia. Lactate dehydrogenase (LDH) is raised while haptoglobin is decreased. Peripheral blood smears show fragmented RBCs. Coombs tests are negative. The organism responsible for this condition is:

A 38-year-old man complains of a persistent high fever with chills, malaise, and diffuse abdominal pain for over a week. He has recently returned from a trip to India. He recalls that the fever began slowly and climbed its way up stepwise to the current 104°F. A physical exam reveals coated tongue, enlarged spleen, and rose spots on abdomen. A bone marrow aspirate was sent for the culture of the organism which revealed motile gram-negative rods. Which of the following is true about the organism and the pathophysiology of this condition?

A young woman presents with complaints of malaise, chills, sore throat, and dry cough. She is a college student and lives in a hostel. Chest x-ray shows interstitial infiltrates that look worse than the symptoms suggest. Nasopharyngeal swab culture shows colonies having fried-egg appearance on Eaton’s agar. Cold agglutinins are positive. Which of the following antibiotics can be prescribed in this case?

A 12-year-old boy in Pakistan presents to the emergency room with complaints of fever, muscle pain, and weakness of the trunk, abdomen, and legs. Physical exam reveals fasciculation and flaccid paralysis of the lower limbs. A CSF analysis reveals lymphocytosis, normal glucose, and protein levels. He has not been vaccinated. Throat swab reveals an RNA virus that destroys:

A group of medical students is studying bacteria and their pathogenesis. They identified that a substantial number of bacteria cause human diseases by producing exotoxins. Exotoxins are protein in nature, but they have a different mechanism of actions and act at different sites. Following is the list of exotoxins with the suggested mechanism of actions; please select the one which is correctly matched. EF = Elongation Factor; cAMP = Cyclic Andenosine monophosphate GABA = Gamma aminobutyric acid

A 26-year-old woman presents to the emergency department with the complaints of increased frequency of urination and lower abdominal pain for the past week. She also has fever with chills. On examination, her temperature is 102F, pulse is 110/min, respirations are 16/min and blood pressure is 122/78 mmHg. Urinalysis reveals pus cells >10/hpf in an uncentrifuged specimen with colony counts >10^5 CFU/ml. Which of the following is the most common organism to cause this pathology in this age group and gender?

A 24-year-old male arrives at the Skin and Venereal Disease clinic with a painless genital ulcer for the past 2 weeks. History revealed he had unprotected sex with a commercial sex worker 3 weeks before. On examination, a single ulcer present on the penis which is circumscribed, indurated and partially healed. There is moderate lymph node swelling but no bubo. Which of the following is the most appropriate next step in the management of this patient?

A 19-year-old female presents to the emergency department with chronic diarrhea, fatigue and weakness. She is also having mild edema on the legs. On examination she is pale. Blood investigation revealed peripheral eosinophilia (60%) and Hb of 8gm/dl. Stool examination revealed egg of Fasciolopsis buski. Which of the following drugs would most likely be effective?

A 50-year-old farmer presents to the physician with a warty lesion on the left feet. Examination revealed warty cutaneous nodules resembling florets of a cauliflower. On KOH preparation irregular, dark brown, and yeast like bodies with septae was found. Culture on Sabouraud Agar revealed sclerotic bodies. Which one of the following is the most likely diagnosis?

A 40-year-old farmer from Ohio comes to the clinic with the complaints of chronic cough, fever, and anorexia for the last couple of months. On examination, he has generalized lymphadenopathy with hepatosplenomegaly. A chest radiograph reveals local infiltrates and patchy opacities all over the lung fields. Fine needle aspiration of an enlarged lymph node shows the presence of intracellular yeast. Fungal culture shows the presence of thick-walled spherical spores with tubercles and microconidia. Which of the following is the most likely diagnosis?

A 50-year-old farmer presents to the physician with a painless black severely swollen pustules on the left hand. Examination reveals painless extensive swelling around the wound. Microscopy reveals gram-positive bacilli with a bamboo stick appearance. Culture shows large, grayish, nonhemolytic colonies with an irregular border. Which of the following is the most likely diagnosis?

A 22-year-old woman with 30 weeks of gestation presents to the obstetrician with sudden onset of fever, headache, anorexia, fatigue and malaise. History revealed she had taken an ice cream 3 days back. Blood culture shows gram-positive rods that are catalase positive and displays a distinctive tumbling motility in liquid medium. What is the most likely diagnosis?

A 65-year-old woman undergoes an abdominal hysterectomy. She develops pain and discharge on from the incision site on the fourth post-operative day. Past medical history is significant for diabetes for the past 12 years which is well controlled on insulin therapy. Pus from the incision site is sent for culture on the MacConkey agar which shows white-colorless colonies and on blood agar the colonies are green. Biochemical tests reveal an oxidase-positive organism. Which of the following is the most likely pathogen?

A 35-year-old woman got admitted to the hospital with complaints of yellowish vaginal discharge, increased urinary frequency, and painful urination. Urine culture revealed the presence of chlamydiae trichomatis. What is the most appropriate next step in management of this patient?

A 30-year-old man from southeast Asia comes to the clinic with the complaints of a bad taste in his mouth and heartburn mostly in the night for the last 6 months. He says that he was tested for H. pylori back in his country and completed a course of multiple antibiotics but there was no improvement in his symptoms. You explain to the patient that he is suffering from a condition which is unrelated to this organism. What is the most likely diagnosis of this patient?

A 3-year-old boy presents to the clinic six months after his family immigrated from Europe. He is anorexic and losing weight. His mother says he has fevers and has started wheezing during the night recently. There is no history of the little kid being exposed to unhealthy foods but he has a puppy at home. The child seems ill and has hepatosplenomegaly on further examination. His lab reports show leukocytosis with predominant eosinophilia even on repeated tests. Which of the following organism or medical condition is the most likely cause of these symptoms in this child?

A 54-year-old truck driver comes to the clinic with the complaints of a painful jaw mass and fever. A yellowish liquid is leaking from the mass now. According to the patient, the mass is increasing in size for the last six weeks ago. He is addicted to alcohol and takes more than six drinks a day. He has a very poor dental hygiene on examination of the oral cavity. Other physical and clinical examination reveal Temperature: 37.9°C / 100.2°F, There is a mass at the tip of the jaw bone containing widespread swelling and sclerosis, severely tender, the patient does not allow the doctor to touch the lesion, with a size of 7 × 7 cm. Lab investigation of the discharge shows gram-positive bacillus growth on anaerobic media. Which one of the given organisms is the cause of this patient's condition?

A 65-year-old man comes to the clinic with the complaints of low-grade fever and malaise for the last four months. He also has lost 20 lbs during this period and says that he does not have the energy to do anything. His last visit to the doctor was 6 months ago when he was doing fine. He had a mitral valve replacement five years ago. On examination, his temperature is 100.6 F, respirations are 22/min, pulse is 102/min and BP is 138/78 mmHg. On cardiac auscultation, a murmur is heard throughout the systole in the apical area of the precordium. He had no murmur in the past. Blood is sent to the lab for culture and an echocardiogram is done. Which of the following organisms is the most likely cause of the patient's condition?

A 24-year-old boy presents with low-grade fever and shortness of breath for the last 3 weeks. He had his mitral valve replaced for severe mitral regurgitation five years ago. Physical examination reveals vertical hemorrhages under his nails, multiple painless erythematous lesions on his palms, and two tender raised nodes on the fingers. Blood cultures show catalase-positive, gram-positive cocci. Which of the following best describes the most common organism for this patient's condition?

A group of researchers conducted various studies on hepatitis C incidence and prevalence. They noticed that there is a high prevalence of hepatitis C in the third-world countries that has great impact on quality of life. Several attempts were made to produce a vaccination that prevents hepatitis C infection, but it failed every time. Which of the following is the reason of this failure?

A 34-year-male presents with painful ulcers on his penis. He is sexually active with multiple partners and uses condom inconsistently. Physical exam reveals multiple small ulcers with erythematous base without discharge. The inguinal lymph nodes are palpable. Which of the following is the most likely etiologic agent of these ulcers?

A 61-year-old female is brought to the clinic with altered mental status. She has an 18-month history of renal transplant, and she is compliant with immunosuppressive medications. On physical examination, the temperature is 39.4°C (103°F), blood pressure is 85/50 mm Hg, the pulse is 135/min. There are several 2-7 mm lesions on the skin of the trunk with necrotic center and erythematous margins. Hemoglobin is 14.2 g/dl, WBC count is 3700/mm³, 22% neutrophils, 52% lymphocytes, 17% monocytes, 5% eosinophils, platelet count is 179 000/mm³, BUN is 15 mg/dl, and creatinine is 0.8 mg/dl. Blood cultures reveal Pseudomonas aeruginosa. Which of the following factors is most likely responsible for this condition?

A senior microbiologist was studying the different CD markers on our immune cells. He noticed that the removal of CD-21 molecule from the surface of B-cells will lead to decreased infections with which of the following causative agents?

A 14-year-old girl presents with sudden drooping of the right side of her face with drooling and excessive tearing. The family informs that she was recently in northern Maine and spent most of the time outside on the trip. Physical examination reveals slight asymmetry of the face with inability to whistle and close the eye. A circular red rash with central clearing was noted on the back. There are also decreased taste sensations. A bite from which of the following most likely transmitted this illness?

A 43-year-old man presents to the infectious disease clinic for a follow-up visit with complains of fever, shortness of breath, and nonproductive cough for the past week. He is known HIV positive and his current CD4 count is 105/microL. He does not take any medications. Physical examination reveals bilateral lung crepitations. Lymphadenopathy is absent. Chest X-ray reveals bilateral infiltrations. What is the best treatment for this patient?

A chronic alcoholic male presents with chronic cough and dyspnoea. He has history of travel to Asia around 4 months back. Examination reveals poor personal hygiene and recurrent productive cough. His temperature is 40.2 ºC and pulse rate is 92/minute. Auscultation reveals decreased air entry on the right side and bronchial breath sounds. A chest radiograph is suggestive of an ill-defined circular lesion in the right middle lobe. Which of the following is true regarding diagnosis of this condition?

A 28-year-old female comes to the clinic in her 12th week of gestation as developed malaise, joint pain, fever, and chills of 3 days duration. Physical examination reveals a mild lace-like rash and arthritis. Her friend who is an intern at medical school told her that the symptoms may be suggestive of parvovirus B19 infection and that it may adversely affect her baby. Which of the following statements regarding this infection during pregnancy is true?

A 28-year-old woman comes to the clinic in her 16th week of gestation for her prenatal care. Routine prenatal screening tests are prescribed. The lab reports reveal positive HIV antibody test and negative VDRL and HBsAg. She is extremely concerned about the transmission of HIV virus to her baby and wants to know the diagnosis at the earliest. Which of the following would be most appropriate to address the mother's concern?

A 4-year-old boy is a known case of cerebral palsy is visiting your clinic. His parents complain of slowly progressive tightness in lower limbs and are concerned as he cannot climb stairs yet. They have been intermittently doing physiotherapy since past 2 years at a specialized centre. At this point, the physician offers another mode of therapy, which involves multiple intramuscular injections in the stiff muscles to relieve tightness. He says that this mode is often used to relieve a type of headache and reduce facial wrinkles. Which of the following is the likely mechanism of action of this drug?

A 37-year-old female with a history of anorectal abscesses complains of pain in the perianal area. Examination reveals mild swelling of the affected area with tenderness and redness. She is started on oral ampicillin and asked to return after 2 days. Two days later, she develops high grade fever, prostration and increased swelling. What is the probable reason of this drug for not being effective?

A 10-year-old boy presents to the emergency department with temperature of 40.5ºC, neck stiffness and drowsiness. He appears dull and confused. He has right sided focal seizures in the ER which are controlled with lorazepam. CT scan of the brain shows left temporal area involvement. An antibiotic is administered. What is the mechanism of action of the drug used in this case?

A 15-year-old girl presents to her primary health care physician with complaints of fever and sore throat since past four days. Examination revealed cervical lymphadenopathy and mild hepatosplenomegaly. Peripheral blood smear shows abnormal lymphocytes and positive Paul – Bunnell (Monospot) test. This patient is most likely infected with which of the following viruses?

A 22-year-old woman presents with an unrelenting headache accompanied by fever, chills, and malaise for the past 4 days. She also complains of an earache and dry hacking cough. On examination, her temperature is 100.2 F, pulse is 104/min, respirations are 20/min and BP is 102/82 mmHg. Chest x-ray shows patchy, diffuse bronchopulmonary infiltrates on both lobes of lung which gives an impression of a very severe disease. Which of the following is the most likely pathogen?

A 26-year-old nurse at 8 weeks of gestation presents to the physician with low-grade fever and body ache for the past two days. She also complaints of a fine rash that appeared last night. The rash first appeared on the face and spread to the trunk. On examination, her temperature is 101 F/ 38.3 C, she has a fine macular rash all over her body and her knee and elbow joints are tender. What is the most appropriate next step in the management of this patient?

A 15-year-old boy is brought to the emergency department with a severe headache and two episodes of vomiting since a couple of hours. The child has fever and malaise for the past 2 days. On examination, he is drowsy with neck stiffness, positive Kernig's sign and temperature of 102 F/ 38.8 C. Cerebrospinal fluid culture on chocolate agar shows gram negative diplococci. Which of the following characteristics describes the most common organism of this condition in this age group?

A 6-year-old boy presents to the emergency department with high-grade fever, headache, and projectile vomiting. On examination, the child was disoriented and kerning's sign positive. Lumbar puncture was done. CSF cytology showed high counts of polymorphs, biochemistry showed low glucose and raised proteins, and gram smear showed the presence of gram positive lanceolate-shaped diplococci inside the polymorph. The culture was positive for alpha hemolytic colonies on sheep blood agar which had the typical “draughtsman colonies” appearance. Which one of the following is the most likely pathogen?

A 24-year-old woman presented with complaints of irritation and frothy yellowish discharge from the vagina. She also complains of pain during sexual intercourse and sometimes after urination. On physical exam, she had inflamed vulval and vaginal mucosa with greenish malodorous discharge. The pH of the vagina is 6. What is the most likely diagnosis of this client?

An 8-year-old child presents to the pediatric emergency department with complaints of profuse diarrhea and vomiting for the last 2 days. Examination reveals poor skin turgor, dry oral mucous membrane. Gross stool examination shows ‘rice water’ appearance. Which of the following is the best diagnostic test to perform at this time?

A 30-year-old woman presented with the complaints fatigue, fever, loss of appetite and small painful blisters on the vagina. History revealed she had two sexual partners before 2 month. Physical examination reveals red clear fluid blisters on the vagina with swollen and tender lymph nodes in the groin. Which of the following is the most likely diagnosis for the client?

A 24-year-old pregnant women at 28 weeks of gestation presents to the emergency department with fever, chill, headache, joint pain and neck stiffness. History revealed a tick bite on her hand while gardening. On examination the physician identified bull’s eye-like rash and ELISA for Lyme disease test was positive. What is the next appropriate intervention for this client?