The number of ill persons identified in each state is as follows: Alabama (2), Arkansas (1), Connecticut (5), District of Columbia (2), Florida (1), Georgia (5), Illinois (10), Louisiana (2), Maryland (11), Massachusetts (8), Mississippi (1), Missouri (2), New Jersey (7), New York (24), North Carolina (2), Pennsylvania (5), Rhode Island (5), South Carolina (3), Texas (3), Virginia (5), and Wisconsin (12).

12 ill persons have been hospitalized, and no deaths have been reported.

Collaborative investigation efforts of state, local, and federal public health agencies indicate that a frozen raw yellowfin tuna product, known as Nakaochi Scrape, from Moon Marine USA Corporation is the likely source of this outbreak of Salmonella Bareilly infections. Nakaochi Scrape is tuna backmeat that is scraped from the bones of tuna and may be used in sushi, sashimi, ceviche, and similar dishes. Moon Marine USA Corporation (also known as MMI) of Cupertino, Calif. is voluntarily recalling 58,828 lbs of a frozen raw yellowfin tuna product, labeled as Nakaochi Scrape AA or AAA. Nakaochi Scrape is tuna backmeat, which is specifically scraped off from the bones, and looks like a ground product.

Consumers should not eat the recalled product, and retailers should not serve the recalled raw Nakaochi Scrape tuna product from Moon Marine USA Corporation.

This investigation is ongoing. CDC and state and local public health partners are continuing surveillance to identify new cases.

LEASA Living Alfalfa Sprouts with use by date 2/1/12 were distributed through FL, GA, AL, LA, and MS through retail stores, including Winn Dixie, and food service companies on 1/4/12, 1/5/12, 1/6/12, 1/7/12 and 1/8/12.

The affected product is in 6 oz. clear plastic containers with a UPC code of 75465-55912 and has an expiration date of 2/1/12. The UPC code is located on the side of the label at the side of the container. The expiration date of the package is located on the side of the container.

No illnesses have been reported to date

The potential for the contamination was discovered when routine customer sample testing on 1/9/12 revealed the presence of Salmonella. 

Customers with any of the LEASA Living Alfalfa Sprouts 6 oz. containers with used by date of 2/1/12 are asked to please dispose of the product by throwing away in the trash receptacle.

Salmonella is an organism that can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Healthy persons infected with Salmonella often experience fever, diarrhea (which may be bloody), nausea, vomiting and abdominal pain. In rare circumstances, infection with Salmonella can result in the organism getting into the bloodstream and producing more severe illnesses such as arterial infections (i.e., infected aneurysms), endocarditis and arthritis.

Yonkers, N.Y.—Consumers Union, the nonprofit publisher of Consumer Reports, today called on the U.S. Department of Agriculture (USDA) to drastically tighten its present Salmonella standard, which allows almost half the samples tested at a ground turkey plant to be contaminated with this disease-causing bug. Consumers Union also called on Congress to give the USDA mandatory recall authority, as it just did for the Food and Drug Administration (FDA) under the Food Safety Modernization Act.

“The current USDA ground turkey standard, which allows 49.9 percent of samples in a test run to be positive for Salmonella is unacceptable and clearly ineffective as a tool for food safety,” said Jean Halloran, Director of Food Policy Initiatives at Consumers Union.

The Center for Disease Control has identified 77 illnesses and one death so far, associated with a strain of Salmonella Heidelberg, found in ground turkey from one processing plant in Arkansas. On August 3, Cargill recalled 36 million pounds of turkey manufactured at the plant since February.

The ground turkey industry generally meets the current very lax USDA standard. USDA tests of 121 samples of ground turkey at 22 ground turkey facilities in the first quarter of 2011 show that 10.7 percent were contaminated, about the same number as for 2010. Consumers Union believes this level is too high and a tighter standard is needed.

“For one in ten packages of ground turkey to potentially be contaminated with disease-causing Salmonella is simply too great a risk,” Halloran said. “The current USDA standard, which allows almost 50 percent to be contaminated, is completely ineffectual as a tool for reducing this level.”

USDA recently reduced its acceptable level of Salmonella in whole turkeys from 19 percent to 1.7 percent contaminated in a given series of tests. “USDA should make a similar drastic reduction in its performance standard for ground turkey,” Halloran said.

Consumers Union points out that similar problems exist with ground chicken, where salmonella levels are even higher—about one third contaminated in USDA’s 2011 first quarter tests—and the USDA standard for acceptable contamination is 44.6 percent of samples. Consumers Union periodically has tested whole chicken and found high levels of bacterial contamination since 1998.

Consumers Union urges consumers to be sure to cook all poultry products well done, to an internal temperature of 165 degrees measured by a meat thermometer and to be very careful to keep packages of raw poultry of any kind away from all other foods in the kitchen.

“Knives and cutting boards used on poultry should go straight into the dishwasher. Turkey burgers on the grill must be well done,” advised Halloran.

“In 1996, the federal government instituted major changes in the meat inspection system by creating the Hazard Analysis Critical Control Point (HACCP) system. Under HACCP, FSIS inspectors shifted to an auditing role and have less authority to require corrective action when they see a problem. As part of HACCP, the agency launched its salmonella testing program, which it touts as an indicator of the effectiveness of meat companies’ food safety procedures. One of the tenets of the HACCP program was that microbial performance standards would be updated regularly. But the salmonella standard that is updated by today’s announcement has been in use since 1998. We urge the agency to regularly revise the salmonella standard and new campylobacter standard in the future.

“In addition to updating the standards regularly, there is still more the agency should do. We are concerned that the agency’s salmonella “report card” will not be as transparent as the one currently used on the agency’s website. In fact, we urge the agency to post the results from all plants — those that fail to meet performance standards, as well as those that marginally pass and those that exceed the standard. A pass/fail listing is not good enough.

“The agency’s decision not to post the results of campylobacter test results by plant will deprive the public of vital information about companies’ progress in reducing this pathogen. Not releasing the plant specific results will force groups like us to use the Freedom of Information Act to seek these results and share them with the public.

“Even when companies fail to meet these performance standard, FSIS does not have the legal authority to shut down the plants or take other enforcement action. It is past time for the agency to seek legislation to make these microbial performance standards enforceable.”

Rattlesnake are commonly feared when they’re alive and rattling, but is there anything to fear when they’re served on a plate with a side of gravy?

Teresa Shisk-Saling, a registered veterinary technician and a herpetologist in Texas A&M University’s College of Veterinary Medicine and Biomedical Sciences, said most of the health concerns surrounding handling and eating rattlesnake can all be avoided by simply being careful.

The first concern is venom. Like most living things, when rattlesnakes die their muscles relax. At that point, the venom is released from their fangs and can spread to other parts of the snake, she said. Venom is isolated to glands in the mouth, so when butchering the reptile, care should be taken to keep the head away from the meat.

“I personally know a couple people that have been poisoned by dead snakes when they were picking them up on the side of the road,” she said. “If venom’s been dripping down the snakes and it touches your hands, you would want to be sure you keep it away from any open wounds or scratches.”

Another concern is salmonella, which can dwell in the gut of the reptile. As long as the intestines are kept intact, she said, toxins would not be exposed to the meat.

Most of the meat available for cooking purposes is commercially available, she said, and is handled and prepared by experienced individuals.

“Most of the folks at things like this know what they’re doing,” she said of the roundup, “but if you get a novice that’s not the brightest bulb in the box you run a risk.”

The significant deviations were as follows:

1. You failed to divert eggs to a treatment that achieves a 5-log destruction of SE upon receiving notification that any of your four egg tests were positive for SE, as required by 21 CFR 118.6(d). Specifically, your firm’s egg testing at Site (b)(4), House (b)(4) resulted in two consecutive SE-positive egg tests. Your firm became aware of the first SE-positive egg test result on October 4, 2010. However, your firm shipped 798 cases of eggs from House (b)(4), on October 7, 2010 to a table egg processor, rather than an egg treatment facility. After our investigators brought this to your attention, you initiated a recall of the eggs on November 5, 2010.

2. You failed to label the pallet, case, or other shipping container, containing eggs being diverted to treatment, with the statement, "Federal law requires that these eggs must be treated to achieve at least a 5-log destruction of Salmonella Enteritidis or processed as egg products in accordance with the Egg Products Inspection Act, 21 CFR 118.6(f),” as required by 21 CFR 118.6(f). Specifically, you diverted eggs from the following locations without the required labeling:

Site # House # Circumstances of Diversion

(b)(4) (b)(4) + SE egg sample 10/04/2010 – 10/28/2010

(b)(4) (b)(4) + SE environmental sample and no subsequent egg testing under § 118.6(a) 10/26/2010 – 11/07/2010

(b)(4) (b)(4) + SE environmental sample and no subsequent egg testing under § 118.6(a) 10/26/2010 – 11/02/2010

(b)(4) (b)(4) + SE environmental sample and no subsequent egg testing under § 118.6(a) 09/22/2010 – 09/28/2010

(b)(4) (b)(4) + SE environmental sample and no subsequent egg testing under § 118.6(a) 09/22/2010 – 10/04/2010

This letter may not list all of your firm's deviations. You are responsible for ensuring that your firm operates in compliance with the Act and all regulations. You also have a responsibility to use procedures to prevent further violations of the Act and all applicable regulations.

Within fifteen working days of receipt of this letter, please notify this office in writing of the specific steps that you have taken to correct violations. Include an explanation of each step being taken to prevent the recurrence of violations, as well as copies of related documentation. If you cannot complete corrective action within fifteen working days, state the reason for the delay and the time within which you will complete the corrections.

You should take prompt action to correct the violations cited in this letter. Failure to promptly correct these violations may result in legal action without further notice, including, without limitation, seizure, and injunction. Other federal agencies may take this Warning Letter into account when considering the award of contracts.

Salmonella infections can cause dairy cattle of all ages to become severely ill. In young calves, it typically shows up as scours, often accompanied by fever. In older animals, it can cause a dramatic drop in milk production, along with fever, diarrhea, bloody stools, dehydration, weight loss, rapid breathing, and/or sloughing of skin from the extremities. Infections can be fast-acting and fatal, or can exist at a subclinical level, with no outward signs of illness.

Salmonellosis is a pervasive disease that is hard to keep out of a dairy operation. Once it is in the herd, it can be devastating to cattle health and performance. As the figure below shows, there are many routes Salmonella transmission can take.

Tips on helping reduce disease exposure:

• Make sure loaders and other feeding equipment are not used simultaneously to handle manure.

• Pasteurize waste milk and colostrum fed to calves.

• Maintain sanitary calving facilities to avoid infecting newborns.

• Keep populations of rodents, feral cats and birds low in feed storage and animal housing areas.

• Control flies throughout the dairy with common fly control methods.

• Restrict visitors and insist on biosecurity measures (such as clean boots and clothing) by all who enter the facility, including the herd veterinarian.

• Clean calf feeding utensils and oral treatment equipment with chlorhexidine (3 ounces per gallon).

• Wash boots regularly with orthophenylphenol (e.g., 1-Stroke Environ), and change and launder work clothes daily. Ideally, boots and work clothing should be left on the dairy.

• Thoroughly sanitize transport trailers, particularly when hauling young calves.

The FDA is inspecting the country's 600 largest egg farms in the wake of a salmonella outbreak in eggs last summer that sickened at least 1,900 people. The agency said Tuesday it has completed 35 inspections and found 76 positive swabs of salmonella in facilities owned by one producer.

The agency declined to name the farm and a spokeswoman said the FDA doesn't yet know if any illnesses were connected to the contamination. The agency said the farm has taken corrective action.

The FDA says it will be done inspecting the farms early next year. The 600 farms represent about 80 percent of the nation's egg supply.

There have been at least 4 illnesses related to the restaurant, and two people who became severely ill have been hospitalized. The restaurant has since closed, and health officials believe that the number of illnesses related to the salmonella bacteria will increase.

Health officials have indicated that the salmonella outbreak at the Don Pericos restaurant is not related to the national egg recall, but have not released the specific strain of salmonella responsible for the illnesses. One official stated that the food at Don Pericos has been sampled for testing and inspectors want to make certain the food is safe for patrons to eat before re-opening.

Officials of the health department inspected the restaurant and discovered numerous food safety violations which was cause for the temporary shut down of the restaurant on Thursday September 2nd. Ongoing investigations continue as health officials try to determine what impact the salmonella outbreak may have had in the area, and how many more individuals may have been infected with the bacteria.

Illnesses that occurred after July 29, 2010 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks for Salmonella.

Epidemiologic investigations conducted by public health officials in 10 states since April have identified 29 restaurants or event clusters where more than one ill person with the outbreak strain has eaten. Data from these investigations suggest that shell eggs are a likely source of infections in many of these restaurants or event clusters. Wright County Egg, in Galt, Iowa, was an egg supplier in 15 of these 29 restaurants or event clusters; three are clusters that have been recently reported, but occurred earlier in the outbreak. Traceback investigations are ongoing for several of these clusters. A formal traceback was conducted by state partners in California, Colorado, and Minnesota, in collaboration with FDA and CDC, to find a common source of shell eggs. Wright County Egg in Iowa was found as the common source of the shell eggs associated with three of the clusters. Through traceback and FDA investigational findings, Hillandale Farms of Iowa, Inc., was identified as another potential source of contaminated shell eggs contributing to this outbreak. FDA is nearing completion of initial investigations at both of these firms in Iowa. The investigations involve sampling, records review and looking for potential sources of contamination, such as feed. FDA’s inspectional observations, in addition to sample results, indicate substantial potential for Salmonella to have persisted in the environment and to have contaminated eggs.

Abstract

The focus of this study was Salmonella enterica serotype Cerro, a potentially emerging pathogen of cattle. Our objectives were to document the within-herd prevalence of Salmonella Cerro among a sample of New York dairy herds, to describe the antimicrobial resistance patterns and pulsed-field gel electrophoresis types of the isolates, and to elucidate the status of this serotype as a bovine pathogen. Data were collected prospectively from dairy herds throughout New York that had at least 150 lactating cows and that received clinical service from participating veterinarians. Following enrollment, Salmonella surveillance consisted of both environmental screening and disease monitoring within the herd. Herds positive by either environmental or fecal culture were sampled during three visits to estimate the within-herd prevalence of Salmonella. Among 57 enrolled herds, 44 (77%) yielded Salmonella-positive samples during the study period. Of these, 20 herds (46%) were positive for Salmonella Cerro. Upon follow-up sampling for estimation of prevalence, Cerro was identified in 10 of the 20 herds; the median within-herd Cerro prevalence was 17%, with a maximum of 53%. Antimicrobial resistance ranged from zero to nine drugs, and eight (40%) of the Cerro-positive farms generated drug-resistant isolates. Eight XbaI pulsed-field gel electrophoresis types were represented among 116 isolates tested, although 89% of these isolates shared the predominant type. Among herds with clinical cases, cattle that had signs consistent with salmonellosis were more likely to test positive for Cerro than apparently healthy cattle, as estimated by a logistic regression model that controlled for herd as a random effect (odds ratio: 3.9). There is little in the literature concerning Salmonella Cerro, and published reports suggest an absence of disease association in cattle. However, in our region there has been an apparent increase in the prevalence of this serotype among cattle with salmonellosis. Other Salmonella serotypes important to bovine health have emerged to become leading causes of human foodborne disease, and close monitoring of Cerro is warranted.

Although the interior of whole cuts of beef products has long been assumed to be sterile, contamination and survival of pathogens have been reported. Studies have found that Salmonella does migrate and survive inside the muscle. Researchers at Michigan State University evaluated the relationship between heat resistance of Salmonella and degree of grinding (whole muscle, coarsely ground, finely ground, and beef puree). All products came from the same original lot of beef and received the same thermal treatment.

Researchers suspected that the water status in meat may impact the effectiveness of Salmonella inactivation and that bacteria may be suspended in the liquid component of the food.

Salmonella exhibited greater heat resistance in whole muscle beef. The physical structure of beef products influenced Salmonella heat resistance. However, no significant difference in thermal resistance was seen between coarsely ground, finely ground and pureed samples, according to lead researcher Bradley Marks.

ABSTRACT

Large volumes of fine particulate matter or "dust" (soil, hulls, and shells) generated when hulls and shells are removed from almond kernels complicate cleaning and sanitation procedures in the huller-sheller (HS) environment. This study evaluated the efficacy of 3 aqueous quaternary ammonium sanitizers (AQuats) and an isopropyl alcohol-based quaternary ammonium sanitizer (IPAQuat) for reducing Salmonella in dust collected from 2 HS facilities. Dust (1 g) was thoroughly mixed with 1 to 2 mL of inoculum (1 to 5 log CFU/g) before adding 1 to 7 mL of water, an AQuat (200 or 1000 ppm), or IPAQuat (200 ppm, 58.6% isopropyl alcohol) and incubated at 15 and 30 °C for up to 21 d. At either 15 or 30 °C increases in Salmonella populations in the dust were not significantly different following addition of either water or AQuats. No significant differences were observed upon water or AQuat addition, either among the 3 AQuats tested, the concentration or volume of AQuat, or the initial level of Salmonella. When IPAQuat was added to dust inoculated at 1 to 7 log CFU/g, Salmonella levels were reduced to less than 1.3 log CFU/g after treatment and after incubation at 30 °C for 48 h. IPAQuat was an effective sanitizer compared to the AQuats, even in the presence of high levels of organic material. Recent large-scale outbreaks of salmonellosis with low-moisture foods have increased concerns regarding their safety. Little research or guidance is available on appropriate cleaning and sanitation programs for these food types. This research is focused on an evaluation of sanitation options for low-moisture foods, in particular almonds. The information should be applicable and useful to the nut industry and to other low-moisture foods.

Practical Application: Recent large-scale outbreaks of salmonellosis with low-moisture foods have increased concerns regarding their safety. Little research or guidance is available on appropriate cleaning and sanitation programs for these food types. This research is focused on an evaluation of sanitation options for low-moisture foods, in particular almonds. The information should be applicable and useful to the nut industry and to other low-moisture foods.

Twelve shipments came from a Bunge plant in Nipawin, Sask. The other originated in Altona, Man.  The canola industry in Canada has said the FDA is cracking down on salmonella because of a series of illness outbreaks since 2006.

Antibiotics and drug-resistance

Many bacterial species have the ability to produce antimicrobial compounds. This ability is needed to give the bacteria an “edge” in microorganism-rich environments. Many of the antibiotics used today originated from bacterial species such as Pennicillium, Cephalosporium, and Streptomyces. Antibiotic-resistance likely also emerged as bacteria began producing compounds in order to survive in their environment, and competing species found ways to counteract these compounds (3).

Antimicrobial agents are currently used for three main reasons: (1) to treat infections in humans, animals, and plants; (2) prophylactically in humans, animals, and plants; and (3) subtherapeutically in food animals as growth promoters and for feed conversion (2). When antibiotic use became the norm in both human and animal medicine, selection pressure increased the bacterial advantage of maintaining and developing new resistance genes that could be shared among bacterial populations (3).

The first suggestion that antibiotic use in livestock led to antibiotic-resistant bacteria was in 1951. Starr and Reynolds reported streptomycin resistance in generic intestinal bacteria from turkeys that had been fed that antibiotic (4).

The use of antibiotics not only selects for antimicrobial-resistant bacteria, but may also increase the likelihood of disease transmission. In 2006, Bauer-Garland et al. researched the transmission of multidrug-resistant (MDR) Salmonella Typhimurium in broiler chicks under selective-pressure. An MDR S. Typhimurium strain had significantly increased transmission when chicks were treated with tetracycline, demonstrating that antimicrobial use influences transmission of antimicrobial-resistant pathogens in poultry (5).

Antibiotics and Salmonella

Although most Salmonella infections are self-limited, causing acute gastrointestinal illness in humans, antimicrobial agents are commonly prescribed to those seeking medical attention. Severe infections that spread to the bloodstream, meningeal linings of the brain, or other deep tissue can also occur. The selection of effective antibiotics is critical for the treatment of invasive infections, but has become more difficult as antibiotic-resistance has increased (2).

In the 1980’s and 90’s, a particular strain of MDR Salmonella, known as Salmonella Typhimurium DT104 (DT104), emerged in the U.S. This strain is typically resistant to at least five drugs: ampicillin, chloramphenicol, streptomycin, sulfisoxazole, and tetracycline (6). Since 1996, the National Antimicrobial Resistance Monitoring System (NARMS) has identified increasing numbers of Salmonella isolates resistant to nine of the 17 antimicrobial agents tested: amoxicillin/clavulanate, ampicillin, cefoxitin, ceftiofur, cephalothin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. These isolates also have decreased susceptibility or resistance to ceftriaxone, an antimicrobial used to treat serious infections in children (7). Salmonella isolates with this resistance pattern carry a gene that produces AmpC-type enzymes that cause much of the drug-resistance; thus they are referred to as MDR-AmpC.

Salmonella Enteritidis is one of the most common types of Salmonella causing human illness, and is associated with consumption of egg-containing products and chicken (8). Since 1996, an increasing number of S. Enteritidis isolates submitted to NARMS have been resistant to nalidixic acid (a drug closely related to ciprofloxacin, or cipro, the most commonly prescribed antibiotic for Salmonella infections). Of these resistant isolates, 90% also showed decreased susceptibility to cipro (7).

Use of antibiotics in agriculture

Antibiotics are used in food animals for several reasons: treatment of sick animals, prophylaxis to prevent illness during times of increased risk of disease (e.g. transport or weaning), a combination of treatment of sick animals and preventative care for other animals in the herd or flock, and for growth promotion and improved feed utilization. The total amount of antibiotics used in food production animals in the U.S. is not known (3).

Antimicrobial agents have played an important role in animal production since the 1950’s. As livestock and poultry farms have grown and animal density on those farms has increased, the demand for better disease management has increased. The use of antimicrobial agents in animal production has improved animal health and led to higher yields. However, this practice has also contributed to the increased prevalence of antibiotic-resistant bacteria significant to human health (3).

The rising prevalence of MDR Salmonella complicates the treatment of Salmonella infections in both humans and animals. A call for prudent use of antibiotics in both human and animal medicine has been issued for years, with some positive results. In 2005, the U.S. Food and Drug Administration (FDA) placed a ban on the use of enrofloxacin (a drug closely related to cipro) in poultry because of the risk that it promotes drug-resistant bacteria that are harmful to human health (9). Opponents to banning antibiotic use in animal agriculture have pointed out that bans like these have, in some cases, led to increased animal morbidity and mortality, and have sometimes contributed to a greater use of antibiotics to treat ill animals. These other antibiotics may come from drug families of greater relevance to human medicine than the drugs that were banned (3).

New data also suggests that use of cephalosporins in the poultry industry could be impacting clinical use in humans. In July, 2008, the FDA proposed a ban of veterinary use of cephalosporins for unapproved methods (such as injection of eggs in hatcheries) due to the likely emergence of cephalosporin-resistant strains of foodborne bacterial pathogens (10). Since cipro is not approved for treatment of Salmonella infections in children under 18 years of age, cephalosporins are an important treatment option for severe infections (11). The American Veterinary Medical Association (AVMA), which represents both public and private sector veterinarians, argued that the FDA’s proposal was unjustified. FDA withdrew the proposal in November, 2008 in order to reconsider all available data on the subject (10).

Antibiotic-Resistant Salmonella in the Food Supply

Antibiotic-resistant Salmonella have been isolated from various food products. In 1998, 20% of ground meat samples were positive for Salmonella, and 84% of these were resistant to at least one antibiotic in the Washington, D.C. area (12). From 1999 to 2003, 18% of Salmonella isolates from various food products tested by the FDA were resistant to two or more antimicrobials (13).

A case-control study of Salmonella Newport infections in the U.S. found that MDR-AmpC infections are acquired through the U.S. food supply from bovine and possible poultry sources (14). Between 2004 and 2005, processed poultry from the mid-Atlantic area of the U.S. was positive for Salmonella in high numbers. Eighty percent of positive samples were resistant to at least one antimicrobial and 53% were resistant to three or more antimicrobials (15). In 2005, Salmonella was detected on 72% of broiler chicken carcasses prior to evisceration and on 20% of carcasses postchill in a sample of 20 U.S. processing plants. Only 15% of the S. Typhimurium var. 5- isolates were pan-susceptible, and more than half of these isolates were resistant to three or more antibiotics (16). In 2006, 22% of raw and ready-to-eat turkey meat purchased in a Midwestern U.S. city was positive for Salmonella. Of these isolates, 62% were multidrug-resistant (17). These results clearly show that MDR Salmonella are present in the food supply, and continued monitoring and research is necessary to track these alarming trends.

Human Infections

Several studies have been published focusing on the severe health consequences from multidrug-resistant Salmonella infections. In 2002, Helms et al. reported on a study in Denmark looking at antibiotic-resistant S. Typhimurium. Patients with MDR infections were 4.8 times more likely to die than the general population, and patients with quinolone-resistant infections were 10.3 times more likely to die (18). In 2004, Helms also reported that patients with quinolone-resistant S. Typhimurium infections had a two-fold increased risk of invasive illness or death within 90 days of infection compared to patients with pan-susceptible infections (19).

Also in 2004, Martin et al. reported on Canadians with MDR S. Typhimurium infection. Hospitalization was more likely in those with MDR infections, and the majority of these hospitalizations were directly attributed to the resistance patterns of the infections (20).

In 2005, Varma et al. published data on bloodstream infections and hospitalizations.
Patients infected with a Salmonella isolate resistant to one or more clinically important antibiotic were three times more likely to be hospitalized with a bloodstream infection than patients with pan-susceptible infections (21).

Outbreaks

Several outbreaks of multidrug-resistant Salmonella infections have been documented in the United States, including an outbreak associated with unpasteurized Mexican-style aged cheese (22), ground beef outbreaks (23, 24, 25, 26), and an outbreak associated with pasteurized milk (27).

In one investigation, hamburger was traced back through meat processing to well beef cattle that had been fed antibiotics (23). In another investigation, chloramphenicol-resistant S. Newport was traced through processing of contaminated ground beef to a dairy farm area. Chloramphenicol-resistant Salmonella was found in manure lagoons, abattoirs, ill dairy cattle, and ground beef. Isolation of chloramphenicol-resistant Salmonella was correlated with chloramphenicol use on the farms (24).

Outbreaks like these can result in multiple hospitalizations and death among individuals with the most severe infections. The multidrug-resistant nature of these organisms makes treatment failure more likely. Antimicrobial agents, particularly fluoroquinolones like cipro, are lifesaving for approximately 2,000 people each year in the U.S. If even 10% of Salmonella isolates in the United States were to become resistant to cipro, and 5% of persons with invasive cipro-resistant infections were to die, the result would be an increase of 10 deaths per year. If 50% of strains became resistant, an additional 100 deaths per year would be expected (2).

Conclusions

There are several reasons to conclude that antibiotic-resistance among human Salmonella isolates are the result of the use of antimicrobial agents in food animal production: (1) tracebacks from foodborne disease outbreaks have shown food animals as the ultimate source of infection (outbreak refs), (2) antimicrobial resistance patterns and genetic fingerprints have shown strong correlation between animal and human Salmonella (2, 6), and (3) antibiotic-resistance in human Salmonella isolates have shown more correlation with antibiotic use in animals than with antibiotic use in humans (2).

Dissemination of MDR Salmonella appears to contribute to changes in resistance patterns. In the U.S., there aren’t restrictions on movement of animal herds positive for S. Typhimurium, though the purchase of infected animals is known to be a risk factor for dissemination. Routine surveillance and intervention (including traceback and quarantine) has reduced the incidence of salmonellosis in food animals in Europe, specifically Norway and Sweden. Biosecurity measures, including protection of feed from rodents and birds, limiting human traffic, disinfection, and separation of newly purchased animals from the larger herd or flock, in addition to testing and quarantine would reduce the risk of introducing MDR Salmonella into a herd or flock. Addressing this issue would subsequently help prevent the unimpeded spread of MDR Salmonella through food animals with consequent human foodborne infection (28).

Some of the same farm management strategies that could help to prevent foodborne disease could also help prevent MDR Salmonella from circulating in the food supply. It ultimately comes down to cost vs. benefit at every step in the chain of responsibility among food producers. Farmers and their veterinarians should be responsible for judicious use of antibiotics in the animal industry just as physicians should be judicious in their use of antibiotics in human medicine. Farmers also need to implement biosecurity measures as outlined above to address problem of dissemination of MDR Salmonella in addition to other infectious agents. In an ideal world, slaughter and food manufacturing facilities would also follow suit, using the best possible practices to minimize foodborne disease transmission to consumers, and federal regulatory agencies would monitor each step in the overall process to ensure the best food safety practices possible. If the problem of antibiotic-resistance is not controlled, larger outbreaks with more severe consequences can be expected. Considering MDR Salmonella to be an official “adulterant” in foods would be a prudent step in helping to curb this emerging foodborne disease threat.

References

2. Angulo F, Johnson K, Tauxe R, and Cohen M. 2000. Origins and Consequences of Antimicrobial-Resistant Nontyphoidal Salmonella: Implications for the Use of Fluoroquinolones in Food Animals. Microbial Drug Resist. 6:77-83.

3. Matthew A, Cissell R, and Liamthong S. 2007. Antibiotic Resistance in Bacteria Associated with Food Animals: A United States Perspective of Livestock Production. Foodborne Path and Dis. 4(2):115-133.

4. Starr MP and Reynolds DM. 1951. Streptomycin resistance of coliform bacteria from turkeys fed streptomycin. Am J Public Health. 41:1375-1380.

5. Bauer-Garland J, Frye JG, Gray JT, Berrang ME, Harrison MA, and Fedorka-Cray PJ. 2006. Transmission of Salmonella enterica serotype Typhimurium in poultry with and without antimicrobial selective pressure. J Appl Micro. 101:1301-1308.

6. Wedel SD, Bender JB, Leano FT, Boxrud DJ, Hedberg C, and Smith KE. 2005. Antimicrobial-drug Susceptibility of Human and Animal Salmonella Typhimurium, Minnesota, 1997-2003. EID. 11(12):1899-1906.

7. CDC. National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS): Human Isolates Final Report, 2006. Atlanta, Georgia: U.S. Department of Health and Human Services, CDC, 2009.

8. Voetsch AC, Poole C, Hedberg CW, Hoekstra RM, Ryder RW, Weber DJ, et al. 2009. Analysis of the FoodNet Case-Control Study of Sporadic Salmonella serotype Enteritidis Infections Using Persons Infected with Other Salmonella Serotypes as the Comparison Group. Epidemiol Infect. 137(3):408-416.

9. CIDRAP: University of Minnesota Center for Infectious Disease Research and Policy. 2005 News release available at: http://www.cidrap.umn.edu/cidrap/content/fs/food/news/july2905baytril.html

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