Ian McHardy , Ph.D . University of California, Los Angeles (UCLA) - PowerPoint Presentation

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Ian McHardy, Ph.D.University of California, Los Angeles (UCLA)

San Franciscan Chicken

Patient HistoryA 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 at UCLASpecimen: 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 plateHektoen Enteric (HE) agar plateCampy Blood agar plateResulting colonies analyzed by:Colony morphologyBiochemical testsAntibody-based serogrouping testsFindings are reported to attending physicians.

Photo Credit: ASM Microbe Library (Hudzicki)

Stool work-up platesSheep Blood agarContains 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.

Photo Credit:

ASM Microbe Library (Buxton)

and

ASM Microbe Library (Miller and Hanley), and ASM Microbe Library (Hudzicki).

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.

Photo Credit:

Wikimedia

Wellcolex Serogrouping for SalmonellaAntibody conjugated latex agglutination test for rapid serogroup

classification of

Salmonella spp.

Latex reagent 1:

Green latex (anti-

Salmonella

grp. D

1

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).

Photos Provided by UCLA.

UCLA PatientStool microbiology findings for the 2 year-old patient:Black colonies grew on Hektoen

-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 PatientBefore 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.

Photo Credit:

Centers for Disease Control and Prevention

Salmonella Heidelberg Outbreak, 201374% 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.

Photo Credit:

Centers for Disease Control and Prevention

Classification - Salmonella species and serotypesOnly 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

.

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 childrenDisseminated infectionAntibioticsObjective is to treat or prevent recurrence of bacteremic disease .FluoroquinolonesAzithromycinTMP-SMX

Classification - Salmonella species and serotypes

Ian McHardy, Ph.D. Ian McHardy

,

Ph.D.

is second year CPEP fellow at UCLA. Dr.

McHardy

studied aspects of the human microbiome for his Ph.D. 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.Photo Credit: Ian

McHardy, Ph.D.