Prevalence, antibiotic resistance and molecular characterisation of Staphylococcus aureus in pigs at agricultural fairs in the USA

Fairs and petting zoos have been associated with outbreaks of zoonotic disease. Previously, the presence of meticillin-resistant Staphylococcus aureus (MRSA) was documented in commercial pigs; therefore, it was hypothesised that antibiotic-resistant S aureus may also occur in pigs exhibited at agricultural fairs. To test this hypothesis, 157 pigs were swabbed at two state fairs in 2008 to 2009. Both nares were sampled and cultures were grown in enrichment broth, then plated onto selective MRSA plates and blood plates. S aureus was confirmed using phenotypic and molecular methods, and was analysed using spa typing, gene-specific polymerase chain reaction and antibiotic susceptibility testing. The presence of S aureus was confirmed in samples collected from pigs exhibited at USA pig shows. Twenty-five of 157 (15.9 per cent) samples were positive for S aureus. Two isolates (8 per cent) were resistant to meticillin; 23/25 (92 per cent), 14/25 (56 per cent) and 15/25 (60 per cent) were resistant to tetracycline, erythromycin and clindamycin, respectively. spa typing revealed multiple isolates of spa type t034 (9/25, 36 per cent) and t337 (7/25, 28 per cent) and singletons of t002, t209, t526, t1236, t1334, t1683, t3075, t5784 and t5883. These results verify the presence of antibiotic-resistant S aureus in pigs exhibited at USA fairs, suggesting that pigs are a potential reservoir for S aureus within this environment.

Recovery of staphylococci from computer keyboards in a veterinary medical centre and the effect of routine cleaning

Computers play a vital role in veterinary clinics for grading, examining results, updating records, giving discharge instructions and maintaining billing information. Few studies have documented the degree of contamination or practical methods to disinfect computer equipment within the veterinary clinic setting. The intent of the present study was to characterise the frequency of recovery of Staphylococcus species from computer keyboards from a veterinary teaching hospital setting and to evaluate the effect of daily cleaning. From three keyboards in a treatment area, three in a dermatology area and one in office 70 environmental samples were cultured for Staphylococcus. As an indirect measure to assess cleanliness, samples were collected and tested using the 3M Clean-Trace Luminometer (relative light units [RLU]). Of the 25 Staphylococcus recovered 13 were Staphylococcus species, seven Staphylococcus pseudintermedius, four Staphylococcus aureus and one mixed colony of both Staphylococcus species and S pseudintermedius. The median RLU was 2098 (range 132 to 11,590). Routine cleaning decreased the recovering of Staphylococcus and the RLU values. In summary, the study results demonstrate the value of routine cleaning of keyboards and the need for on-going and regular education of staff and students about good hand hygiene.

The potential capability of social media as a component of food safety and food terrorism surveillance systems

Social media (i.e., internet applications and platforms that allow users to create and share content) are a potentially rich data source for foodborne disease surveillance. This commentary qualitatively evaluates social media as a foodborne disease surveillance system component and discusses novel ways that social media may facilitate the detection of intentional and unintentional food contamination.

Antibody prevalence of low-pathogenicity avian influenza and evaluation of management practices in Minnesota backyard poultry flocks

Low-pathogenicity avian influenza (LPAI) viruses have caused illness in poultry and humans with poultry contact. To determine whether there is evidence of exposure to avian influenza viruses (AIV) among backyard poultry in Minnesota and their human caretakers, 150 flocks of backyard birds were sampled for antibodies to AIV from August 2007 through December 2008. One hundred flocks were tested through routine slaughter surveillance by the Minnesota Board of Animal Health and an additional 50 flocks were contacted and sampled by study investigators. Blood was collected from 10 to 13 birds from each flock and a survey of biosecurity and management practices was administered to the flock owner. Blood samples were tested by agar gel immunodiffusion (AGID) for influenza A antibodies. Tested flocks had a median flock size of 100 birds (range: 12-800 birds), and were most commonly owned for meat for personal use (81% of respondents), fun or hobby (58%) and eggs for personal use (56%). Although 7% of flock owners reported that their birds had shown respiratory signs in the previous 3 months, only 1 of 150 flocks tested positive for influenza by AGID. Antibodies to LPAI H6N1 were detected in the positive flock. The owner of the positive flock did not have antibodies to H6 or other common AIV. Based on the findings of this study, the risk of transmission of LPAI viruses from backyard poultry to owners in Minnesota appears to be low under current conditions and management practices.

Decreased use of cervical spine clearance in blunt trauma: the implication of the injury mechanism and distracting injury

BACKGROUND

Cervical spine injury (CSI) can be ruled out based on clinical examination and no X-ray is required if patient is awake, alert, and examinable. This is known as a clinical clearance (CC). Clinicians have decreased the use and reliance of CC and relied more upon X-ray, especially now that computerized tomography (CT) is fast and readily available. The objective of this study was to identify clinical factors, in particular, the injury mechanism and the distracting injuries, which may be associated with CSI. The knowledge may help to improve the use of CC.

METHODS

We retrospectively reviewed the records of all blunt trauma patients who were awake, alert, and examinable, with a Glasgow Coma Scale of 14-15, and who were admitted to our Level 1 Trauma Center during January 1 to December 31, 2005. We excluded patients who presented with gross neurological deficit or who died within 72 h. From the chart review, we collected the demographics; the injury severity score (ISS); the injury mechanism; the presence of distracting injuries (DI) which were defined as bony fractures (divided into upper body, lower body, or both); and the radiographs obtained. Patients who did not receive CC underwent a 3-view plain film X-ray, with or without CT scan. We then divided the group into those with CSI (Case) and those without (Control). We compared the two group variables and performed a multiple logistic regression analysis to identify clinical factors associated with CSI. Statistical significance was accepted with p-value <0.05.

RESULTS

Of the 985 patients evaluated, only 179 (18%) received CC. The remaining did not receive CC and went on to have radiographs. Of these, 76 were diagnosed CSI (Case). On a univariate analysis, the ISS, a motor vehicle collision (MVC) with rollover; MVC with rollover and ejection, the absence of DI, and a lower-body DI were significantly associated with CSI. However, on a multivariate analysis, only an MVC with rollover (odds ratio [OR], 2.326; 95% confidence interval [CI], 1.36-3.97) and a lower-body distracting injury (OR, 0.20; 95% CI, 0.07-0.55) were significantly associated with CSI.

CONCLUSION

The injury mechanism of MVC with rollover may prevent clinicians from utilizing CC, while the presence of a lower-body DI should not. A future and prospective study is needed to better understand the role of the injury mechanism and the distracting injury in relation to CSI.

Methicillin-resistant Staphylococcus aureus in resident animals of a long-term care facility

Animals provide benefits to elderly and chronically ill people by decreasing loneliness, increasing social interactions, and improving mental health. As a result, many hospitals and long-term care facilities allow family pets to visit ill or convalescing patients or support animal-assisted therapy programs. These include programs that have resident animals in long-term care facilities. Despite the benefits, there are concerns about disease transmission between pets and patients. Antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are a recognized problem in healthcare settings leading to refractory infections and potentially life-threatening illnesses. MRSA has been isolated from numerous animal species, yet few studies are available on the carriage of this pathogen in animals residing in long-term care facilities. Our objective was to characterize MRSA carriage among resident animals in a long-term care facility.

METHODS

To document MRSA colonization, nasal swabs from 12 resident animals (one dogs and 11 cats) of a long-term care facility were collected weekly for 8 weeks. Staphylococcus isolates were characterized by antimicrobial susceptibility and MRSA isolates were further characterized by pulsed-field gel electrophoresis (PFGE). PFGE isolate patterns were compared with an existing database of MRSA isolate patterns at the Minnesota Department of Health.

RESULTS

Two of 11 cats were colonized with MRSA. MRSA was recovered from five of eight weekly samples in one cat and two of eight weekly samples in the other cat. All isolates were classified as USA100 (healthcare-associated strains).

DISCUSSION

Long-term care resident animals may acquire MRSA. Clonally related strains were identified over the 8-week sampling period. It is unclear if pets serve as an on-going source of infection to their human companions in long-term care facilities.

Anaplasma phagocytophilum infection in dogs: 34 cases (2000-2007)

OBJECTIVE- To determine demographic characteristics of dogs from the upper Midwest infected with Anaplasma phagocytophilum and identify clinical and clinicopathologic abnormalities and response to treatment. DESIGN- Retrospective case series and owner telephone survey. ANIMALS- 34 dogs with granulocytic anaplasmosis. PROCEDURES- Records were reviewed for information on signalment, history, physical examination findings, clinicopathologic and serologic findings, and treatment. Owners were contacted by telephone within 4 months after dogs were discharged. RESULTS- Median age was 8 years. Distribution of month of diagnosis was bimodal, with 15 dogs examined during May or June and 11 others examined during October or November. Camping and hiking were the most frequently reported tick exposure activities. Lethargy (25/34) and anorexia (21/34) were the most common initial complaints, fever was the most common clinical sign (27/32), and thrombocytopenia was the most common clinicopathologic abnormality (21/22). Fifteen of 20 dogs were seropositive for antibodies against A phagocytophilum. Doxycycline was prescribed for 31 dogs, and clinical signs and fever resolved within 3 to 5 days. Median time for platelet count to return to reference limits was 7 days. No owners reported clinical sequelae when contacted after dogs were discharged. CONCLUSIONS AND CLINICAL RELEVANCE- Results suggested that granulocytic anaplasmosis should be suspected in dogs in endemic areas examined because of fever, lethargy, or thrombocytopenia, especially in dogs examined during the late spring or early fall. Treatment with doxycycline was successful in resolving clinical signs and thrombocytopenia.

Pets and antimicrobial resistance

Antimicrobial resistance is a growing problem and is a significant public health issue. An increasing number of organisms are developing resistance to many of the antimicrobial agents available for treatment of infections in both humans and animals. These resistant organisms often result in greater disease severity, longer hospitalization, and increased care and treatment costs. This article reviews the current situation of antimicrobial resistance in companion small animals and highlights how important it is for veterinarians to recognize the significance of antimicrobial resistance and to commit to the judicious use of antimicrobial agents.

Diseases pets and people share

Having a companion animal such as a dog, cat, or pocket pet is increasingly popular in the United States. With more human-animal interactions come additional opportunities for disease exchange. This article highlights common zoonoses associated with pets and provides recommendations for preventing disease transmission, including hand hygiene, client or patient education, and appropriate pet care. The article also discusses human diseases in which animals may be mistakenly implicated as the source and the recent identification of human diseases such as methicillin-resistant Staphylococcus aureus in companion animal populations. The article also calls for the strengthening of integrated animal and human surveillance systems and cooperation of medical and veterinary practitioners.

Outbreaks of enteric disease associated with animal contact: not just a foodborne problem anymore

In the past 10 years, an increasing number of outbreaks of enteric disease associated with animals in public settings, such as fairs and petting zoos, have been reported. Fifty-five of these outbreaks that occurred in the United States during 1991-2005 are reviewed in this article. Lessons learned from these outbreaks and recommendations for prevention are also discussed. Physicians should be aware of this important public health problem and play an active role in prevention of human illness associated with animals in public settings.

Circumstances of Bat Encounters and Knowledge of Rabies among Minnesota Residents Submitting Bats for Rabies Testing

Minnesota residents who submitted a bat to the Minnesota Department of Health for rabies testing in 2003 were surveyed by telephone regarding the circumstances of the bat encounter and their knowledge of bats and rabies. Of 442 bats submitted for testing, 12 (3%) tested positive for rabies, and 410 (93%) tested negative; 17 (4%) bats were unsuitable for testing, and three (1%) had equivocal results. A case-control study found that rabid bats were more likely than non-rabid bats to be found in September, found outside, found in a wooded area, unable to fly, acting ill, or acting aggressively. Rabid bats were not more likely than non-rabid bats to be found during the day or to have bitten someone. While most persons submitting bats for rabies testing were aware that bats can carry rabies, few knew they should submit the bat for testing until they sought the advice of an animal control officer, veterinarian, or healthcare provider.

Multidrug-resistant Salmonella Typhimurium in four animal facilities

Within each of 4 outbreaks of S. Typhimurium among humans and animals at companion animal care facilities, isolates were identical or nearly identical.

In 1999 and 2000, 3 state health departments reported 4 outbreaks of gastrointestinal illness due to Salmonella enterica serotype Typhimurium in employees, clients, and client animals from 3 companion animal veterinary clinics and 1 animal shelter. More than 45 persons and companion animals became ill. Four independent investigations resulted in the testing of 19 human samples and >200 animal samples; 18 persons and 36 animals were culture-positive for S. Typhimurium. One outbreak was due to multidrug-resistant S. Typhimurium R-type ACKSSuT, while the other 3 were due to multidrug-resistant S. Typhimurium R-type ACSSuT DT104. This report documents nosocomial transmission of S. Typhimurium and demonstrates that companion animal facilities may serve as foci of transmission for salmonellae between animals and humans if adequate precautions are not followed.

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms

The objective of this study was to evaluate associations between herd characteristics and the isolation of Salmonella from dairy cows in Minnesota, Wisconsin, Michigan, and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. This is the largest study to date on Salmonella shedding in dairy cows and the only study evaluating herd-level risk factors using longitudinal sampling to characterize Salmonella shedding on dairy farms. Salmonella was isolated in fecal samples from 1026 (4.9%) of 20,089 cows. Over the course of the study, 113 (87.6%) of 129 farms had at least one positive cow sample. Multi-variable logistic regression using the generalized estimating equations approach was used to test the association between herd-level risk factors and the dependent variable of within-herd prevalence by visit (number of Salmonella-positive cows/number of cows sampled) after adjustment for effects of herd size, season, state of origin, and the multiple sampling occasions per herd. Factors retained in the final model included lack of use of tiestall or stanchion facilities to house lactating cows (OR=1.9; 95% CI: 1.1-3.3), not storing all purchased concentrate or protein feeds in an enclosed building (OR=2.5; 95% CI: 1.3-4.9), not using monensin in weaned calf or bred heifer diets (OR=3.2; 95% CI: 2.0-5.4), access of lactating or dry cows to surface water (e.g., lake, pond, river, or stream) (OR=2.3; 95% CI: 1.3-3.9), disposal of manure in liquid form (slurry or irrigation, as opposed to disposal of manure by broadcast/solid spreader only) on owned or rented land (OR=1.8; 95% CI: 1.3-3.9), and cows eating or grazing of roughage from fields where manure was applied in solid or liquid form and not plowed under during the same growing season (OR=1.8; 95% CI: 1.0-3.0). A seasonal association was also present as cows were more likely to be Salmonella-positive in summer, spring, and fall compared to winter. Herd size was not associated with Salmonella shedding in the final multi-variable model. The herd-level risk factors identified in this study could potentially be implemented in Salmonella control programs on dairy farms.

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms

The objective of this study was to evaluate associations between herd-level factors and the isolation of Salmonella in calves from dairy farms in Minnesota, Wisconsin, Michigan and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. Salmonella was isolated in fecal samples from 176 (3.8%) of 4673 preweaned calves with 40 (31.0%) of 129 farms having at least one positive calf sample over the course of the study. Multivariable logistic regression using the generalized estimating equations approach was used to evaluate risk factors for Salmonella shedding after adjustment for effects of herd size, season, state of origin and the multiple sampling occasions per herd. Factors retained in the final model that were associated with an increased odds for Salmonella shedding were lack of routine feeding of milk replacer containing antimicrobials to preweaned calves (OR=2.8, 95% CI: 1.4, 5.8), use of maternity housing as a hospital area for sick cows more than once a month (OR=2.1, 95% CI: 1.1, 4.0), and cow prevalence level by visit, categorized into the following four-levels: > or =20% (OR=11.6, 95% CI: 5.7, 23.7), 10-19.9% (OR=4.7, 95% CI: 2.0, 11.5), 0.1-9.9% (OR=3.6, 95% CI: 1.5, 8.7) and 0% (reference level). Herd size was not associated with Salmonella shedding in the final multivariable model.

Horses and the risk of zoonotic infections

Infectious agents are insidious, often changing to adapt to host defenses or treatment advances. Because these challenges will continue, the need to apply standard and transmission-based precautions is important not only in the human hospital setting but in the veterinary clinic setting. In addition, to prevent human infection and potential liability, clinics need to establish program algorithms to prevent disease spread for specific agents or planned procedures to respond to potential nosocomial and zoonotic disease events. These need to be done proactively. Furthermore, more money needs to be dedicated to establish infection control programs and to improve the science of infection control in the veterinary setting.

Reports of zoonotic disease outbreaks associated with animal exhibits and availability of recommendations for preventing zoonotic disease transmission from animals to people in such settings

OBJECTIVE

To assess the number of zoonotic disease outbreaks associated with animal exhibits and identify published recommendations for preventing zoonotic disease transmission from animals to people in exhibit settings.

DESIGN

Literature review and survey of state public health veterinarians and state epidemiologists.

PROCEDURE

MEDLINE and agriculture databases were searched from 1966 through 2000. Retrieved references and additional resources provided by the authors were reviewed. A survey was sent to state public health veterinarians and state epidemiologists to determine whether their states had written recommendations or guidelines for controlling zoonotic diseases in animal exhibition venues, whether their states maintained a listing of animal exhibitors in the state, and whether they had any information on recent outbreaks involving animals in exhibitions.

RESULTS

11 published outbreaks were identified. These outbreaks occurred in a variety of settings including petting zoos, farms, and a zoological park. An additional episode involving exposure to a potentially rabid bear required extensive public health resources. A survey of state public health veterinarians identified 16 additional unpublished outbreaks or incidents. Most states did not have written recommendations or guidelines for controlling zoonotic diseases or any means to disseminate educational materials to animal exhibitors.

CONCLUSIONS

Recent outbreaks of zoonotic diseases associated with contact with animals in exhibition venues highlight concerns for disease transmission to public visitors. Only a handful of states have written guidelines for preventing zoonotic disease transmission in animal exhibition venues, and published recommendations currently available focus on preventing enteric diseases and largely do not address other zoonotic diseases or prevention of bite wounds.

Mites (Acari: Laelapidae) associated with sigmodontinae rodents in Entre Ríos Province, Argentina

The richness, diversity, abundance and prevalence of mite species associated with sigmodontine rodents of different species in Entre Ríos province, Argentina are studied. Five of the six species of mites were reported for the first time in the study area. The richness and diversity of mites was higher on Oligoryzomys flavescens and O. delticola than on Akodon azarae. Androlaelaps rotundus was dominant and exhibited higher values of mean abundance and prevalence on A. azarae, Mysolaelaps microspinosus on O. flavescens and Gigantolaelaps mattogrossensis on O. delticola.

Use of molecular subtyping in surveillance for Salmonella enterica serotype typhimurium

BACKGROUND

Because Salmonella enterica serotype typhimurium is the most common serotype isolated from persons with salmonellosis in the United States, it is difficult to detect unusual clusters or outbreaks. To determine whether molecular subtyping could be useful in public health surveillance for S. enterica serotype typhimurium, the Minnesota Department of Health initiated the routine use of pulsed-field gel electrophoresis (PFGE) of isolates.

METHODS

Beginning in 1994, all S. enterica serotype typhimurium isolates submitted by clinical laboratories to the Department of Health were subtyped by PFGE. A standard questionnaire was used to interview patients about possible sources of infection.

RESULTS

From 1994 through 1998, 998 cases of infection with S. enterica serotype typhimurium were reported to the Minnesota Department of Health (4.4 cases per 100,000 person-years). PFGE was performed on 958 of the isolates (96 percent), and 174 different patterns were identified. Sixteen outbreaks with a common source were identified, accounting for 154 cases. PFGE subtyping made it possible to confirm 10 outbreaks that involved small numbers of cases in institutional settings. Of six larger, community-based outbreaks, four would probably not have been recognized without PFGE subtyping. These four outbreaks accounted for 96 of the 154 culture-confirmed outbreak cases (62 percent). Fifty-six of 209 isolates tested for antimicrobial susceptibility (27 percent) were resistant to at least five antimicrobial agents. The multidrug-resistant isolates identified had unique PFGE patterns.

CONCLUSIONS

Routine molecular subtyping of S. enterica serotype typhimurium by PFGE can improve the detection of outbreaks and aid in the identification of multidrug-resistant strains. Combining routine molecular subtyping with a method of rapid communication among public health authorities can improve surveillance for S. enterica serotype typhimurium infections.

The changing epidemiology of malaria in Minnesota

Malaria cases reported to the Minnesota Department of Health increased from 5 in 1988 to 76 in 1998, paralleling the number of immigrants to Minnesota. In 20% of cases, the Plasmodium species was not identified; 44% of cases were hospitalized. The public health community needs to reevaluate current recommendations for refugee screening, provider and patient education, and laboratory capacity.

Food-borne disease in the 21st century. What challenges await us?

As the world shrinks and international commerce expands, food-borne illness is likely to become a major public health focus worldwide. Improved surveillance, community education, thorough understanding of the food production chain, use of HACCP strategies, and ionizing radiation are all important for reducing the risks. Primary care physicians play a crucial role in surveillance and early reporting, as well as in educating the public on the importance of basic food safety.

Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. Investigation Team

BACKGROUND

Increasing resistance to quinolones among campylobacter isolates from humans has been reported in Europe and Asia, but not in the United States. We evaluated resistance to quinolones among campylobacter isolates from Minnesota residents during the period from 1992 through 1998.

METHODS

All 4953 campylobacter isolates from humans received by the Minnesota Department of Health were tested for resistance to nalidixic acid. Resistant isolates and selected sensitive isolates were tested for resistance to ciprofloxacin. We conducted a case-comparison study of patients with ciprofloxacin-resistant Campylobacter jejuni isolated during 1996 and 1997. Domestic chicken was evaluated as a potential source of quinolone-resistant campylobacter.

RESULTS

The proportion of quinolone-resistant C. jejuni isolates from humans increased from 1.3 percent in 1992 to 10.2 percent in 1998 (P<0.001). During 1996 and 1997, infection with quinolone-resistant C. jejuni was associated with foreign travel and with the use of a quinolone before the collection of stool specimens. However, quinolone use could account for no more than 15 percent of the cases from 1996 through 1998. The number of quinolone-resistant infections that were acquired domestically also increased during the period from 1996 through 1998. Ciprofloxacin-resistant C. jejuni was isolated from 14 percent of 91 domestic chicken products obtained from retail markets in 1997. Molecular subtyping showed an association between resistant C. jejuni strains from chicken products and domestically acquired infections in Minnesota residents.

CONCLUSIONS

The increase in quinolone-resistant C. jejuni infections in Minnesota is largely due to infections acquired during foreign travel. However, the number of quinolone-resistant infections acquired domestically has also increased, largely because of the acquisition of resistant strains from poultry. The use of fluoroquinolones in poultry, which began in the United States in 1995, has created a reservoir of resistant C. jejuni.

Animal by-products contaminated with Salmonella in the diets of lactating dairy cows

As part of a total mixed ration, two rumen-fistulated dairy cows were fed meat and bone meal that had been artificially contaminated with Salmonella spp. Samples from the rumen, feces, and milk were taken 3 d/wk and cultured for salmonella. Rectal temperatures and rumen pH were also measured at the time of sample collection. Over the 2-mo study, salmonella were intermittently recovered from rumen contents, from feces, and from necropsy specimens of rumen contents, cecal contents, and mesenteric lymph nodes. No excretion of salmonella in milk was detected. An elevated rumen pH was associated with increased isolation of salmonella. No clinical illness was observed for either cow. Meat and bone meal that has been contaminated with low concentrations of salmonella is unlikely to result in clinical illness in healthy adult lactating cows. However, dairy producers should continue to be concerned about feed biosecurity and water contamination of animal by-products to prevent and control contamination by salmonella.