Os 214 Digestive: Emerging Foodborne Diseases

BACKGROUND ■ ■ ■ ■

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Food safety has emerged as a major public health issue Increasing dramatic statistics of outbreaks of foodborne diseases (FBDs) Foods of animal origin often implicated as vehicles of transmission “emerging” foodborne zoonoses e.g. E. coli O157, Listeria monocytogenes, Campylobacter jejuni and Yersinia enterocolitica FBDs associated with changing methods of agriculture and technology Re-emerging infections such as cholera - still a major threat in developing countries

Emerging diseases: diseases whose incidence has increased within the past 2 decades or threatens to increase in the near future ■ Global travel ■ Irrigation, deforestation and reforestation ■ globalization of food projects that alter habits supply and centralized of disease-carrying processing of foods insects ■ population growth ■ Increased use of and increased antimicrobial agents urbanization and and pesticides, crowding hastening the ■ population movement development of due to civil wars, resistance famines and other ■ Human habits and man-made or natural behavior disasters

Diarrheagenic E. coli Infections ■

Enteropathogenic E. coli) (EPEC) – Damage to intestinal epithelial cells – Infant and children’s diarrhea

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Enterotoxigenic E. coli (ETEC) – “traveler’s diarrhea”, cholera-like

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Enteroinvasive E. coli (EIEC) – Similar to shigellosis or bacillary dysentery

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Enterohemorrhagic E. coli (EHEC) – “all blood, no stool” – E. coli O157 Alice Alma C. Bungay

“Hamburger syndrome” Alice Alma C. Bungay

-Hemorrhagic colitis (HC) -Hemolytic uremic syndrome (HUS) -Thrombotic, thrombocytopenic purpura (TTP) Also known as the “hamburger syndrome” Dairy and beef cattle as reservoirs

Laboratory Diagnosis: Some important features of E. coli O157- sorbitol negative colonies are formed -use of SMAC or CT-SMAC

Prevention: -Consumers should follow advice not to eat raw or undercooked beef or drink raw milk -Adequate cooking of minced beef and minced beef products

Laboratory Diagnosis: Specimens: stool Cold enrichment: 21 days PBS pH 7.9 4˚C and plate on CIN and BAP “bulls-eye colonies” Grows better at 25˚ rather than 37˚C Biochemical test-API 20E

Treatment, Prevention and Control: -In

cases of abscess and bacteremia, trimethoprim-STX or ciprofloxacin usually effective -There are no preventive measures except to guard against contamination of food by excreta of domestic animals

PATHOGENESIS

Laboratory Diagnosis: Specimens: stool Cultured on Skirrow’s medium with vancomycin, trimethoprim, cephalothin, polymixin and amphoteracin B -Plate incubated containing 5% oxygen and 10% carbon dioxide -failure to grow at 25˚C, oxidase positive and sensitivity to nalidixic acid -darting motility, comma or S-shaped curved rod; asaccharolytic Blood culture in cases of bacteremia

LABORATORY DIAGNOSIS

Treatment, Prevention and Control: ■ -Erythromycin and ciprofloxacin is used ■

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in C. jejuni enterocolitis There is no vaccine or other specific preventive measure Proper sewage disposal and personal hygiene is important

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Challenges: – Detecting outbreaks – Determining fractions of cases related to poultry – Consumer education – Reducing the development of resistant strains – Identifying sources and syndromes associated with campylobacters other than jejuni – Preventing the sale of raw milk

HELICOBACTER PYLORI

HELICOBACTER PYLORI

HELICOBACTER PYLORI

HELICOBACTER PYLORI

HELICOBACTER PYLORI

HELICOBACTER PYLORI Laboratory Diagnosis: -Organisms can be Gram-stained using smears of biopsy specimens from gastric mucosa -Can be cultured in same media used for campylobacters -Urease –positive -Presence of IgG can be used as evidence of infection -use of “urease breath test” where radio- labeled urea is ingested, if the organisms are present, - carbon dioxide is evolved and radioactivity is detected in the breath

Treatment, Prevention and Control: -Treatment of duodenal ulcers with antibiotics with antibiotics, amoxicillin, metronidazole and bismuth salts results in greatly decreased recurrence rate -There is no vaccine or other specific preventive measure

Listeria monocytogenes

Gram-positive Bacilli ■

Irregular, non-sporing, aerobic bacilli – Corynebacterium diptheriae

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Regular, non-sporing, aerobic bacilli – Erysipelothrix rhusiopathiae

– Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Environmental sources: silage

Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Listeria monocytogenes

Listeria

Listeria monocytogenes

Listeria monocytogenes

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Epidemiology – Transmission • Ingestion of contaminated food products • Transplacental

– Who is at risk? • Neonates: early onset disease is called granulomatosis infantiseptica charcterized by disseminated abscesses, granulomas and high mortality rates • Late onset: 2-3 weeks after birthmeningitis and septicemia • Elderly and Immunocompromised adults: Meningitis and septicemia • Pregnant women: abortion, first as flu-like symptoms • Endocarditis and bacteremia

Listeria monocytogenes ■

Laboratory diagnosis – Use of cold enrichment – Pre-enrichment/enrichment such as UVM broth,Fraser broth selective media such as Listeria agar, McBride, Oxford agar and PALCAM agar – Identification based on: • Gram stain, gray colonies with halo on PALCAM • Hemolysis on BAP, narrow zone of beta hemolysis, Motilitytumbling motility, end to end with characteristic inverted test tube brush on semi solid agar • Catalase positive • Absence of hydrogen sulfide • Hemolysis by CAMP test using test organisms • Blue colonies by Henry’s illumination • API Listeria • Serotyping: 1/2a, 1/2b and 4b commonly reported in outbreaks

Listeria

Listeria monocytogenes ■

Geography/Season: – Ubiquitous and worldwide – Sporadic with peak of occurrence during warmer months

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Modes of Control: – People at high risk should avoid eating raw or partially cooked foods of animal origin, soft cheeses, drink unpasteurized milk or eat unwashed vegetables – Penicillin or ampicillin alone or with combination with aminoglycoside can be used – Refrigeration is not a guarantee to kill the pathogen since this thrives in cold environment

Listeria monocytogenes

Alice Alma C. Bungay