Question

Please give the genus and species of each answer.

11. The colonies are typically large, gray-white and opaque on blood agar. Most strains recovered from clinical isolates are nonpigmented; colonies with a deep red pigmentation may be encountered. On MacConkey agar they appear nonpigmented after 24 hours but become lactose positive. The bacterial cells are gram-negative straight rods. The biochemical reactions are indole negative, methyl red negative, VP positive, motile, citrate positive, urease negative, and hydrogen sulfide negative ___________________________________________________________________________________

12. The colonies are typically large, gray-white and opaque on blood agar. On MacConkey agar they appear nonpigmented characteristic of non-lactose fermenters. On selective enteric media containing ferrous iron (HE, XLD), colonies may have a deep black pigmentation from production of hydrogen sulfide. The bacterial cells are gram-negative straight rods. The biochemical reactions are indole negative, methyl red positive, VP negative, motile, citrate positive, urease negative, and hydrogen sulfide positive. ___________________________________________________________________________________

13. Family members attended a reunion in Cape Cod and five persons became ill. Their symptoms included malaise, anorexia, and mild icterus. All patients had abnormal liver function tests. All patients recovered uneventfully. Other family members received gamma globulin. All patients denied a history of exposure to blood transfusions, parenteral drug use, and foreign travel. At the reunion, the patients had shared one meal together at which only steamed clams were served. Six persons ate the clams, and five became ill.

___________________________________________________________________________________

14. Two brothers, age 7 and 11, killed a sitting rabbit with a BB gun. Three days later the 11-year-old boy became ill with severe headache, and on the following day he was admitted to a local hospital with temperature of 103 F. Both the brother and the boys' mother, who had assisted in cleaning the rabbit, experienced similar symptoms. The mother had an indurated cutaneous lesion on the middle finger of her left hand and generalized lymphadenopathy. All three persons responded clinically to tetracycline and chloramphenicol.

___________________________________________________________________________________

15. A 66-year-old resident of New Mexico, traveling through Texas, became ill with fever and general malaise. The following day he was admitted to a hospital with a fever of 103 F, nausea, weakness and lower extremity myalgia. No lymphadenopathy or abnormal lung findings were apparent. Blood specimens were positive for gram-negative organisms, and the patient was begun on chloramphenicol and gentamycin. The patient's general condition improved rapidly following antibiotic therapy, although fever persisted for 10 days; his clinical course was punctuated by an episode of pulmonary edema. Persistent pulmonary infiltrates were thought to be related to congested heart failure rather than to pneumonia. He was discharged after a two week hospitalization and at present is asymptomatic. Epidemiological investigation by the Texas State Department of Health revealed that the patient had spent most of the previous month at his brother's ranch in New Mexico, where he had handled dead mice; he did not recall being bitten by fleas. During the two days immediately preceding his illness, the patient had been traveling in Texas. He spent one night on a ranch in Texas, but had no contact with rodents there.

___________________________________________________________________________________

16. A 38-year-old man in Alabama developed bilateral paresthesia and pain in his ears, headache, sore throat, and anorexia. These symptoms persisted and later were accompanied by fever, difficulty swallowing, confusion, and tremor. He was admitted to the hospital with a temperature of 105 F, nuchal rigidity, confusion, agitation, and spasmodic tremors. Physical examination admission revealed dysarthria, dysphagia, pharyngeal paralysis, and drooling. Stimulation of the patient precipitated spasms with spontaneous flexion of all extremities. A lumbar puncture revealed no marked abnormalities. Seven days later, the patient had pharyngeal and laryngeal spasms, subsequent cyanosis, and suffered a respiratory arrest; he was resuscitated immediately. Reviewing the patient's history he had been bitten on the right ear by a bat four weeks prior to admission. The bat had escaped and the patient had sought medical care. Over the next few days, the patient lapsed into a coma. Neurologic examination revealed facial paralysis, generalized hypoflexia, and response to only deep pain. No other focal abnormalities were present. Initially the patient was treated with diphenylhydantoin, diazepam, and chlorpromazine. Once the coma ensued, the sedatives were discontinued. Proteinuria, hypothermia and hypoxia subsequently developed. Despite intensive respiratory care, antibiotics, postural drainage, use of bronchodialators, and vigorous suctioning, hypoxia persisted. The patient developed a pneumothorax, had a cardiorespiratory arrest and died.

___________________________________________________________________________________

17. You are working in a Los Angeles emergency room. At 2 A.M., a man and two women arrived with a screaming 5-year old child. The man tried to explain what was wrong, but he spoke only spanish and you had a difficult time understanding him. The child's mother was sobbing and you couldn't hear what she was saying. The other woman spoke a bit of english and explained that this was her family who just arrived from El Salvador. She said the father kept repeating the word for break bone. The child was examined and presented with a rash, a fever of 104 F but not broken bones or fractures. What is your diagnosis?

___________________________________________________________________________________

18. A 9-year-old boy was brought by his father for evaluation of crampy abdominal pain, nausea, and mild diarrhea that had persisted for approximately two weeks. On the day before the evaluation, the boy reported to his parents that he had passed a large worm into the toilet during a bowel movement. He flushed the worm before the parents could see it. Physical examination was completely unremarkable. The boy had no fever, cough, or rash and did not complain of anal pruritus. His travel history was unremarkable. Examination of a stool specimen revealed the diagnosis. Which nematode was likely in this case?

___________________________________________________________________________________

19. A 45-year-old Egyptian was referred for evaluation of hematuria and urinary frequency of 2 months’ duration. This individual had lived in the Middle East for most of his life but for the past year lived in the United States. He denied previous renal or urologic problems. His physical examination was unremarkable. A midstream urine specimen was grossly bloody. What was the etiologic agent of the patient’s urologic process?

___________________________________________________________________________________

20. A 63 –year-old international telecommunications executive visits your office with complaints of high fever. The fever is not constant, but intermittent. He says that every three days or so he suffers from these debilitating “sweats”. He usually has headaches and muscle aches during these episodes. They are so bad that he can’t go to work. After a day or so he feels better. He has been having these episodes for several months. What is the name of the condition you suspect?

Answer 1

Question 11- Serratia marcescens

Genus Serratia is characterised by production of a red non diffusible pigment named prodigiosin. However most clinical isolates will be non pigmented. Among the different species, Serratia marcescens produce infection in humans. It is a Gram negative bacilli, catalase positive, oxidase negative, gives grey white moist colonies (occasionally red pigmented) in blood agar, usually non lactose fermenting colonies on MacConkey agar. Indole not produced, Triple sugar iron agar shows alkaline slant /acid butt, gas produced, no hydrogen sulfide production, urea not hydrolysed, citrate utilised, nitrate reduced to nitrite. It is motile. Methyl red negative and VP positive

Other features are production of lipase, DNAase, gelatinase.

Question 12

Salmonella other than Salmonella Typhi and Paratyphi A

Genus Salmonella is a Gram negative bacilli. Catalase negative, oxidase positive, gives grey white moist colonies on blood agar and non lactose fermenting colonies on MacConkey agar. Indole not produced, Triple sugar iron agar shows alkaline slant /acid butt, gas produced (except Salmonella Typhi), Hydrogen sulfide produced except Salmonella Paratyphi A, motile, citrate utilised (except Salmonella Typhi and Paratyphi A), urea not hydrolysed, nitrate reduced to nitrite, methyl red positive and VP negative. On special media like XLD, red coloured colonies seen, black centres are produced by those producing hydrogen sulfide.