Question

B. A 30-year-old dairy farmer Ralph was in good health until the day prior to admission, when he felt chilled and feverish. He developed nausea, vomiting, diarrhea and lower abdominal discomfort; he presents to the emergency room, where he is noted to be lethargic. His vital signs include temperature of 104o F, blood pressure of 100/60 mmHg in the supine position and 80/60 mmHg sitting and a pulse of 80 beats/min. His physical examination is remarkable for lower abdominal tenderness to palpation bilaterally. A rectal examination reveals occult blood in the stool. Ralph is lethargic but has no focal neurological deficits. Of note, his 3-year-old son had been discharged from the hospital 2 days prior with a similar history.The patient underwent lumbar puncture because of his altered mental status and fever. Lab studies of the CSF are within normal limits and a bacterial culture of the CSF was negative. Ralph is treated with IV fluids and antibiotics, and his condition improves. A stool examination for fecal leukocytes was positive, and a stool culture was diagnostic. Biochemical examination of the microbe revealed it to be a lactose nonfermenter on MacConkey agar, H2S negative, urea negative, and nonmotile at both 77o F, and 98.6o F. 4.

Based on the biochemical reactions, what genus is it? How do you know this? 5. Ralph's wife and child also had this infection. Was this individual’s vocation important in the epidemiology of this infection in his family? Explain your answer.

Answer 1

• The associated organism is lactose non-fermenting. Further, the symptoms indicate that the probable causative agent may be Moraxella sp.
• Moraxella cannot ferment lactose and thus does not produce positive result (red/ pink colonies) on MacConkey medium.
• Moraxella are Gram negative (diplococci), non-motile, aerobic organisms.
• They may be present as normal flora of respiratory tracts, skin, mucous membrane, genital tract.
• It mostly causes infection of children (Moraxella catarrhalis commonly causes otitis media in young children).
• Moraxella may cause, meningitides,respiratory problems, pneumonia, gastrointestinal problems.
• The infection may be caused as nosocomial infection, in immunocompromised individuals, from person – person contact. Also the fomites, or substances in contact with infected person (like clothings) may spread the disease.
• Thus, the connection of the patient with his, infected son and wife derive the epidemiology of the organism, as it spreads through contact.