OTHER FOODBORNE OTHER FOODBORNE INFECTIOUS BACTERIA � Infectious bacteria only INFECTIOUS BACTERIA � May be transmitted by food, water or contact PHR 250 � Some are not conclusively proved to be foodborne— criteria for “foodborne” Categories Historic foodborne agents � Historic foodborne agents � Brucella spp. � Sometimes foodborne � Corynebacterium diphtheriae � Questioned foodborne � Mycobacterium bovis pathogens (1) Brucella spp. Brucella spp. � Brucellosis (Malta fever) is a Species of concern are: worldwide problem. � B. abortus (cattle) � Incidence of brucellosis in the US: � B. melitensis & B. ovis (sheep – ~ <0.5 cases per 100,000 & goats), – Most reported from California, � B. suis (swine), and Florida, Texas, and Virginia. � B. canis (dogs; although rare).
Brucella spp. Brucella spp. Food vehicles: Transmission of Brucella is usually zoonotic. The organism is carried � Unpasteurized milk (cows, and shed by animals. sheep, or goats) and milk � Livestock such as cattle (beef and products. dairy) are a primary source of the � Carcasses of infected animals pathogen, at least in the US. (including swine and buffalo)— � Some pets (e.g., dogs) also a don’t typically lead to consumer source. infections. Brucella spp. Brucella spp. � Pasteurization will destroy the � Incubation period is 5 d–2 mo. Brucella— avoid drinking raw � Recurrent, prolonged, febrile, milk and eating raw-milk cheese systemic infection. � No vaccines available for � Recurrences are common and humans. may be accompanied by arthritis. � Live vaccines available for � Antibiotic treatment animals, may cause disease in humans. (2) Corynebacterium diphtheriae C. diphtheriae � Diphtheria first clinically described by � Toxigenic (phage-mediated) Hippocrates in the 4 th century B.C. infection, usually of upper � An epidemic swept Europe in the 17 th respiratory tract century. Called “El garatillo” (the � Life-threatening strangler) in Spain & the “gullet � Controlled by vaccination of disease” in Italy. humans (no animal hosts) � Reached American colonies in the 18 th century—whole families wiped out.
C. diphtheriae (3) Mycobacterium bovis � Milkborne outbreaks recorded � M. bovis causes a contagious and in the US before widespread debilitating disease in humans practice of immunization and and animals called bovine pasteurization of milk (machine tuberculosis (TB). milking?). � WHO: ~8 million new cases and � No foodborne outbreak reported 3 million deaths each year. in recent years in the US. Mycobacterium bovis Mycobacterium bovis � Most common means of contracting � Food vehicles: Mainly raw cows' the disease is through inhalation of milk and its products. aerosols containing the agent. � Tuberculosis caused by M. bovis � In 2002, California lost its TB-free indistinguishable from M. status after three herds tested tuberculosis ; infects consumers via positive for the disease. the digestive tract → extrapulmonary tuberculosis more likely Mycobacterium bovis Bacteria rarely foodborne � Most heat-resistant of milk-borne pathogens are M. bovis and C. � Clostridium difficile burnetii . � Coxiella burnetii � The heat resistance of M. bovis provided the basis for the � Streptococcus pyogenes conditions of high-temperature, short-time pasteurization (72 ° C, 15s) of milk.
Bacteria rarely foodborne Bacteria rarely foodborne Clostridium difficile : Coxiella burnetii : � Free-living in soil & sediments � Globally distributed � Can contaminate foods, but not � Causes Q-fever specifically shown to be foodborne � Primary reservoirs: sheep, cattle, � Causes diarrhea after antibiotics— goats, companion & wild altering flora allows C. difficile to grow in intestinal tract, produce animals, birds, ticks toxin, & cause watery diarrhea. Coxiella burnetii Coxiella burnetii � Commonly airborne (risk to vets � C. burnetii is a highly infectious & herdsman in contact with agent. animals, especially at parturition) � Resistant to drying, heat, and a � Can be shed in milk of infected number of disinfectants. animals (basis for low- temperature, long-time � It can survive for long periods in pasteurization) the environment. Streptococcus pyogenes Streptococcus pyogenes (= Group A) � Most common vehicle is raw � Groups B, C, D, F, and G. cows' milk, but any food (potato � Based on a combination of antigenic, salad, eggs, egg salad, and rice hemolytic, and physiological traits pudding) may be contaminated by infected handler. � Groups A and D can be foodborne & cause human illness. � Infective dose is low (est. <1000 � Group A = one species ( S. pyogenes ) cells). with 40 antigenic types.
Questioned foodborne Streptococcus pyogenes pathogens � CDC (U.S., ’98-’02): 1 outbreak, � Aeromonas hydrophila 4 cases, 0 deaths � Enterococcus spp. � CAST: 52,000-500,000 cases, 150 deaths/yr, $540/case � Plesiomonas shigelloides � Pseudomonas aeruginosa Aeromonas hydrophila Aeromonas hydrophila � The bacterium is found in all • . freshwater environments, and brackish • Some strains can cause illness in fish and water humans. � Causation of diarrhea and transmission • Often found in human intestines (normal and via food or water have not yet been diarrheal); proposed cause of diarrhea in humans conclusively proven. (especially young children). � Suspected food vehicles: fish, shellfish, and meats including beef, pork, lamb, and poultry. Plesiomonas shigelloides Enterococcus (fecal Strep .) spp. � Found in humans with watery diarrhea � The genus Enterococcus is new (causation not proved, but two name for fecal Streptococcus . outbreaks have been documented in Japan) or with septicemia, often � Experiments have failed to cause accompanied by meningitis. illness in human volunteers. � Most reported cases of � Transmission via food and water gastroenteritis involve people with is proposed, but unproven. pre-existing health problems (e.g., cancer, sickle-cell anemia).
Plesiomonas shigelloides Pseudomonas aeruginosa � Suspected to be waterborne — disease � Opportunistic pathogen agent might be present in unsanitary � Alleged to cause gastroenteritis in water used for drinking, recreational humans if ingested in large purposes, or rinsing foods to be eaten raw. numbers. � Eating contaminated, raw shellfish � Can be isolated from soil and may lead to illness. All reported water and is commonly associated foods involved with cases of with spoilage of food such as eggs, gastroenteritis were of aquatic origin cured meats, fish and milk. (salted fish. crabs, and oysters). “Emerging foodborne Pseudomonas aeruginosa pathogens” � P. aeruginosa is pathogenic only when introduced into areas lacking � Agents not previously recognized normal defenses such as tissue as foodborne damage of mucous membranes and � Agents in food, not previously skin, severe burns, intravenous or recognized as pathogenic urinary catheters. � Problems with Koch's postulates � Transmission via food and water is � "Old" agents, newly named proposed, but unproven. Summary “At risk” populations, U.S. � "Emerging" vs disappearing � Age > 65 29,400,000 foodborne pathogens (affluent � Pregnant women 5,657,900 countries) � Newborns 4,002,000 � On-farm measures vs zoonoses � Cancer outpatients 2,411,000 � Some agents that occur in foods � Nursing home residents 1,553,000 may threaten only "vulnerable" � AIDS patients 135,000 populations � Organ transplant patients 110,270 � Some alleged pathogens may be virtually harmless
“At risk” populations, U.S. Age > 65 29,400,000 Pregnant women 5,657,900 Newborns 4,002,000 Cancer outpatients 2,411,000 Nursing home residents 1,553,000 AIDS patients 135,000 Organ transplant patients 110,270
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