Los Tacos

LOS TACOSOlabade and Urma

Debriefing 67 cases in NJ, NY, PA, DE, and SC

Bloody diarrhea and severe abdominal cramps

of 67, 51 hospitalized and 8 kidney failures (hemolytic-uremic syndrome)

November 20 - December 5

Peak in the last week of November

Had all eaten at a Taco Bell

Chopped yellow onions tested positive for a pathogen; DNA fingerprinting confirms onions were not source of the infection

Possible Culprits Escherichia coli

Pseudomonas aeruginosa

Salmonella enterica

Staphylococcus aureus

Streptococcus pyogenes

Haemophilus influenzae

Gram Stain E. coli = gram –

S. aureus = gram +

Sample = ?

Gram Stain

Gram Stain

Gram Stain

Gram Stain

Gram Stain

Gram Stain

Gram Stain

Gram Stain

Microscopic

S. aureus

E. coli

Sample

First Elimination Escherichia coli (Gram-) Rod Shaped

Pseudomonas aeruginosa (Gram-) Rod Shaped

Salmonella enterica (Gram-) Rod Shaped

Staphylococcus aureus (Gram+) Spherical

Streptococcus pyogenes (Gram+)Spherical

Haemophilus influenzae (Gram-) Rod Shaped

Selective/Differential Media

MacConkey Agar Salt bile is selective aspect

Lactic acid is differential aspect

Grows Gram- bacteria and stains for lactose fermentation

Lac+ CO2, acid, and alcohol agar will become a bright pink/red color when lactose is

fermented because the acid lowers the pH

Lac- cannot ferment the lactose colorless

Gram+ can’t ferment lactose because the bile salts do not allow for them to grow, therefore not allowing them to ferment the lactose

MacConkey Agar

Second Elimination Escherichia coli (Gram-) Rod Shaped (Lac +)

Pseudomonas aeruginosa (Gram-) Rod Shaped

(Lac-)

Salmonella enterica (Gram-) Rod Shaped (Lac-)

Haemophilus influenzae (Gram-) Rod Shaped

(Lac +)

Escherichia coli orHaemophilus influenzae?Escherichia coli

Can cause: Food poisoning

Diarrhea

Gastroenteritis

Urinary Tract Infection

Haemophilus influenzae

Can cause: Bacteremia

Pneumonia

Acute Bacterial Meningitis

Usually in kids

It’s… E. coli!! Gram –

Rod shaped

Generally aerobic

Most strains are opportunistic pathogens

Capsulated and Non-Capsulated

Cell Wall/Shape/Arrangement

Outer membrane of cell wall is lipopolysaccharide that functions as endotoxin can lead to inflammation, high fever, hypotension, capillary

damage, intravascular coagulation, tissue degradation, and irreversible shock

Some pili let bacterium adhere to epithelial cells of the mucous membranes

Some cell wall adhesions let bacterium make more intimate contact with the mucous membranes

Some strains secrete enterotoxins that cause the loss of sodium ions and water from the small intestines watery diarrhea

Some strains secrete a toxin that kills epithelial cells of the large intestines bloody diarrhea

Metabolism Facultative Anaerobe

Metabolizes glucose in both the presence and absence of oxygen

Location in Nature Lower intestine of warm-blooded organisms

Can be found in: Unpasteurized milk and apple cider

Ham, turkey, chicken, roast beef, sandwich meats

Raw vegetables, cheese

Contaminated water

Damaging Human Host

Can severely damage lining of intestines

Resulting in

Epidemiology Consumption of contaminated foods

Hand- mouth

Human-human

Antimicrobial Susceptibility Test

Antimicrobial Susceptibility Test

Antimicrobial Susceptibility Test

E. Coli (mm) Staph (mm)

Gentamycin 21 (S) 10 (R)

Penicillin 0 (R) 27 (R)

Vancomycin 0 (R) 12 (S)

Chloramphenicol 25 (S) 17 (I)

Streptomycin 13 (I) 12 (I)

Tetracycline 22 (S) 19 (S)

Tetracycline Generally used in fighting infections of

urinary tract and intestines

Protein Synthesis Inhibitor

Kills bacterial cells by inhibiting their translation

Binds to 30S ribosomal subunit Prevents tRNA from binding to ribosome

Conclusion Patients ingested raw or undercooked meat

with E. coli from Taco Bell

Caused an infection

Tetracycline is the best antibiotic to give them Will halt the protein synthesis in the E. coli