San Franciscan chicken

Patient History A 2 year old male with a very complicated medical history presented to the UCLA emergency department with fever, diarrhea, myalgias, rhinorrhea, dehydration, and decreased activity. The patient had a medical history significant for heart transplant and post-transplant lymphoproliferative disorder. He lived with 3 siblings, one of which was sick with similar diarrheal symptoms.

Enteric Work-up @ UCLA Specimen: Fresh stool was collected and sent in a transport container to the UCLA clinical microbiology lab for culture. Workup in the clinical microbiology lab: Stool plated onto: Blood agar plate (BAP) MacConkey’s agar plate Hektoen Enteric (HE) agar plate Campy Blood agar plate Resulting colonies analyzed by: Colony morphology Biochemical tests Antibody-based serogrouping tests Findings are reported to attending physicians.

Stool work-up plates Sheep Blood agar MacConkey agar – Contains blood and nutrients for growth of many bacteria. Both Gram-positive and Gram-negative bacteria can grow. MacConkey agar – Contains bile salts and crystal violet, which inhibit the growth of most Gram-positive bacteria.  Bacteria that ferment lactose appear pink on this agar.  Hektoen Enteric (HE) agar HE contains bile salts, lactose, acid fuchsin and bromo thymol blue indicators.  Lactose fermenters produce yellow – orange colonies. Colonies that produce hydrogen sulfide (H2S) appear black.

API 20E by bioMerieux Principle: The strip consists of 20 microtubes containing dehydrated substrates. The tests are inoculated with bacterial suspensions that reconstitutes the media. During incubation, specific bacterial metabolites are produced that can be detected via color changes. Based on this information, bacterial identification is often possible.

Wellcolex Serogrouping for Salmonella Antibody conjugated latex agglutination test for rapid serogroup classification of Salmonella spp. Latex reagent 1: Green latex (anti-Salmonella grp. D1 Abs) Blue latex (anti-Salmonella grp. C Abs) Red latex (anti-Salmonella grp. B Abs) Latex reagent 2: Blue latex (anti-Salmonella grps. E & G Abs) Red latex (anti-Vi Abs) Green latex (anti-Salmonella grp. A Abs)

UCLA Patient Stool microbiology findings for the 2 year-old patient: Black colonies grew on Hectoen-Enteric agar. Biochemical tests on sub-cultured black colonies indicated the organism was a Salmonella species. Wellcolex serogrouping determined the isolate was a Salmonella enterica subspecies enterica serogroup B (Red latex from reagent 1). Antimicrobial susceptibility testing was performed. Los Angeles County Public Health Laboratory determined the isolate as a Salmonella enterica subspecies enterica serotype Heidelberg (part of a larger US outbreak). Antibiotic Sensitivity MIC in µg/mL Ampicillin Resistant >32 Ciprofloxacin Susceptible 0.03 Bactrim Susceptible <=1/20

UCLA Patient Before culture completion, the patient was discharged without antibiotics for presumed viral enteritis. Given the patient’s age and complicated medical history, antibiotics were warranted to ensure full recovery. Antibiotics were prescribed and the patient improved. The clinical microbiologist provided an unexpected diagnosis that resulted in a dramatic change in patient care.

Salmonella Heidelberg Outbreak, 2013 74% of the 389 infected persons were from California. Among 389 persons with available information, 40% reported being hospitalized. 14% of ill persons developed blood infections as a result of their illness. Typically, only ~5% of persons ill with Salmonella infections develop blood infections. No deaths were reported. Several isolates were multi-drug resistant. At least some of the cases were attributable to Foster Farms Chicken purchased at Costco in San Francisco, CA. CDC.gov, 2013

Classification - Salmonella species and serotypes Only two species of the genus Salmonella are recognized: S. enterica – composed of six sub-species (I, II, IIIa, IIIb, IV, VI). S. bongori – formerly subspecies V (20 serotypes). 6 subspecies of S. enterica. >2500 serotypes of S. enterica subsp. Enterica.

Treatment for Salmonella Gastroenteritis Oral or intravenous rehydration. Generally antibiotics are not recommended. Agents do not shorten course of illness. Antibiotic resistance increasing problem. Antibiotics can prolong excretion of Salmonella. Exceptions include high risk groups. Underlying disease or complicated medical history Young children Disseminated infection Antibiotics Objective is to treat or prevent recurrence of bacteremic disease . Fluoroquinolones Azithromycin TMP-SMX

Ian McHardy, Ph.D. Ian McHardy, PhD is second year CPEP fellow at UCLA. Dr. McHardy studied aspects of the human microbiome for his PhD thesis and postdoctoral fellowship. His research interests involve linking bioinformatics with basic and clinical research to drive improved diagnostics, disease monitoring, and therapies for infectious diseases.