BackgroundSurra is an animal trypanosomosis, caused by infection with Trypanosoma evansi and leading to severe economic loss due to mortality and morbidity. Compared to tsetse-transmitted animal trypanosomoses, little attention is given to the epidemiology and control of surra. Understanding its epidemiology is a first step in local and global efforts to control the disease. We conducted a systematic review and meta-analysis of published studies on distribution, host ranges and prevalence of T. evansi infection.MethodsFour electronic databases were searched for publications on T. evansi that met our inclusion criteria for the systematic review. Subsets of publications were subjected to meta-analysis for the pooled prevalence of T. evansi in various hosts as determined by multiple detection methods.ResultsA total of 272 references published between 1906–2017 were included. Trypanosoma evansi was reported from 48 countries; largely confined to Africa and Asia with publications on natural T. evansi infections from 77% (n = 48) of countries, contrasting with seven countries in South America, and four in Europe where T. evansi is not endemic but was imported with infected animals. Although surra is a notifiable disease, many countries do not report surra cases to OIE. Trypanosoma evansi was mainly reported from dromedary camels in Africa and the Middle East, water buffaloes, cattle, dogs and horses in East and Southeast Asia. In South America, the acute form of the disease was reported in horses and dogs. Surra was also reported in a wide range of wild animals. Some rare human cases occurred in India and Vietnam. Meta-analysis on a subset of 165 publications indicated pooled prevalence of T. evansi in domestic animals ranging from 14–31%, 6–28% and 2–9% using respectively antibody detection, molecular and parasitological tests, with camels as the most affected, followed by buffalo and cattle.ConclusionsThis study illustrates that T. evansi affects a wide range of domestic and wild animals in Africa, Asia and South America with highest prevalence observed in dromedary camels. For successful control of T. evansi, both locally and globally, the role of wild animals in the epidemiology of surra needs further investigation.Electronic supplementary materialThe online version of this article (10.1186/s13071-019-3311-4) contains supplementary material, which is available to authorized users.

This study compared the populations of antimicrobial-resistant bacteria and the repertoire of antimicrobial resistance genes in four environments: effluent of three municipal wastewater treatment facilities, three cattle feedlot runoff catchment ponds, three swine waste lagoons, and two “low impact” environments (an urban lake and a relict prairie). Multiple liquid and solid samples were collected from each environment. The prevalences and concentrations of antimicrobial-resistant (AMR) Gram-negative (Escherichia coli and Salmonella enterica) and Gram-positive (enterococci) bacteria were determined from individual samples (n = 174). The prevalences of 84 antimicrobial resistance genes in metagenomic DNA isolated from samples pooled (n = 44) by collection date, location, and sample type were determined. The prevalences and concentrations of AMR E. coli and Salmonella were similar among the livestock and municipal sample sources. The levels of erythromycin-resistant enterococci were significantly higher in liquid samples from cattle catchment ponds and swine waste lagoons than in liquid samples from municipal wastewater treatment facilities, but solid samples from these environments did not differ significantly. Similarly, trimethoprim/sulfamethoxazole-resistant E. coli concentrations were significantly higher in swine liquid than in municipal liquid samples, but there was no difference in solid samples. Multivariate analysis of the distribution of antimicrobial resistance genes using principal coordinate analysis showed distinct clustering of samples with livestock (cattle and swine), low impact environment and municipal samples forming three separate clusters. The numbers of class A beta-lactamase, class C beta-lactamase, and fluoroquinolone resistance genes detected were significantly higher (P < 0.05) in municipal samples than in cattle runoff or swine lagoon samples. In conclusion, we report that AMR is a very widespread phenomenon and that similar prevalences and concentrations of antimicrobial-resistant bacteria and antimicrobial resistance genes exist in cattle, human, and swine waste streams, but a higher diversity of antimicrobial resistance genes are present in treated human waste discharged from municipal wastewater treatment plants than in livestock environments.

BackgroundThere is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia.MethodsVarious samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods.ResultsAt the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested.Conclusions E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7.

Specific concerns have been raised that third-generation cephalosporin-resistant (3GC r ) Escherichia coli, trimethoprim-sulfamethoxazole-resistant (COT r ) E. coli, 3GC r Salmonella enterica, and nalidixic acid-resistant (NAL r ) S. enterica may be present in cattle production environments, persist through beef processing, and contaminate final products. The prevalences and concentrations of these organisms were determined in feces and hides (at feedlot and processing plant), pre-evisceration carcasses, and final carcasses from three lots of fed cattle (n ‫؍‬ 184). The prevalences and concentrations were further determined for strip loins from 103 of the carcasses. 3GC r Salmonella was detected on 7.6% of hides during processing and was not detected on the final carcasses or strip loins. NAL r S. enterica was detected on only one hide. 3GC r E. coli and COT r E. coli were detected on 100.0% of hides during processing. Concentrations of 3GC r E. coli and COT r E. coli on hides were correlated with pre-evisceration carcass contamination. 3GC r E. coli and COT r E. coli were each detected on only 0.5% of final carcasses and were not detected on strip loins. Five hundred and 42 isolates were screened for extraintestinal pathogenic E. coli (ExPEC) virulence-associated markers. Only two COT r E. coli isolates from hides were ExPEC, indicating that fed cattle products are not a significant source of ExPEC causing human urinary tract infections. The very low prevalences of these organisms on final carcasses and their absence on strip loins demonstrate that current sanitary dressing procedures and processing interventions are effective against antimicrobial-resistant bacteria.

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The specific antimicrobial resistance (AMR) decreases that can be expected from reducing antimicrobial (AM) use in United States (US) beef production have not been defined. To address this data gap, feces were recovered from 36 lots of "raised without antibiotics" (RWA) and 36 lots of "conventional" (CONV) beef cattle. Samples (N = 719) were collected during harvest and distributed over a year. AMR was assessed by: i) culture of six AM-resistant bacteria (ARB); ii) qPCR for 10 AMR genes (ARGs); iii) an qPCR array of 84 ARGs; and iv) metagenomic sequencing. Generally, AMR levels were similar, but some were higher in CONV. The prevalence of third-generation cephalosporin-resistant (3GC) was marginally different between production systems (47.5 % CONV, 34.8% RWA, = 0.04), but the seasonal effect (92.8% summer, 48.3% winter, < 0.01) was greater. Erythromycin-resistant (ERY) spp. concentrations significantly differed between production systems (CONV = 1.91 log CFU/g, RWA = 0.73 log CFU/g, < 0.01). Levels of ,, (A),(B), (C),(F), (Q),(A), (B),(M), and (X) ARGs were higher ( < 0.05) in CONV. Aggregate abundances of all 43 ARGs detected by metagenomic sequencing and the aggregate abundances of ARGs in the aminoglycoside, β-lactam, macrolide-lincosamide-streptogramin B (MLS), and tetracycline AM classes did not differ (log fold change < 1.0) between CONV and RWA. These results suggest that further reductions of AM use in US beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance. The majority of AM use in the US is for food-animal production, leading to concerns that typical AM use patterns during CONV beef cattle production in the US contribute broadly to AMR occurrence. In the present study, levels of AMR were generally similar between CONV and RWA cattle. Only a limited number of modest AMR increases were observed in CONV, primarily involving MLS and tetracycline resistance. Macrolides (tylosin) and tetracyclines (chlortetracycline) are administered in-feed for relatively long durations to reduce liver abscesses. To ensure judicious AM use, the animal health, economic, and AMR impacts of shorter duration in-feed administration of these AMs should be examined. However, given the modest AMR reductions observed, further reductions of AM use in US beef cattle production may not yield significant AMR reductions beyond MLS and tetracycline resistance.

Staphylococcus aureus is a frequent and major contagious mastitis bacterial pathogen. The antibiotic treatment cure rates vary considerably from 4% to 92%. Staphylococcus aureus readily becomes resistant to antibiotics, resulting in persistent noncurable intramammary infection that usually results in culling of infected animals. Because of its notorious ability to acquire resistance to the commonly used as well as last resort antimicrobials such as methicillin and vancomycin and the development of multidrug-resistant strains, antimicrobial resistance (AMR) in S. aureus is of paramount importance in human medicine. The objective of this study was to evaluate the prevalence of AMR and genetic diversity of S. aureus isolates from milk of dairy cattle. Staphylococcus aureus isolates (n = 239) from 33 dairy farms in Tennessee were tested against 10 antimicrobials by broth microdilution method using the Sensititer system. Genetic diversity of resistant isolates was evaluated by pulsed-field gel electrophoresis (PFGE). Overall, AMR of the S. aureus isolates varied from as low as 1.3% for ceftiofur to as high as 25% for sulfadimethoxine. Out of 239 S. aureus isolates, 82 (34.3%) of them were resistant to at least 1 of the 10 antimicrobials. The AMR isolates belonged to two major PFGE types, indicating the presence of dominant clonal patterns among the resistant isolates. In general, there was a variation of prevalence of AMR within and among farms over time, with an increasing trend in tetracycline resistance. Judicious use of antimicrobials in dairy cattle farms can reduce the development of antimicrobial-resistant S. aureus.

Concerns have been raised that in-feed chlortetracycline (CTC) may increase antimicrobial resistance (AMR), specifically tetracycline-resistant (TET r ) Escherichia coli and third-generation cephalosporin-resistant (3GC r ) E. coli. We evaluated the impact of a 5-day in-feed CTC prophylaxis on animal health, TET r E. coli, and 3GC r E. coli. A control group of cattle (n ‫؍‬ 150) received no CTC, while a CTC group (n ‫؍‬ 150) received in-feed CTC (10 mg/lb of body weight/day) from the 5th to the 9th day after feedlot arrival. Over 25% (38/150) of the animals in the control group developed illnesses requiring therapeutic treatment with antimicrobials critically important to human medicine. Only two animals (1.3%) in the CTC group required such treatments. Fecal swab and pen surface occurrences of generic E. coli (isolated on media that did not contain antimicrobials of interest and were not isolated based on any specific resistance), TET r E. coli, and 3GC r E. coli were determined on five sampling occasions: arrival at the feedlot, 5 days posttreatment (5 dpt), 27 dpt, 75 dpt, and 117 dpt. On 5 dpt, TET r E. coli concentrations were higher for the CTC group than the control group (P < 0.01). On 27 dpt, 75 dpt, and 117 dpt, TET r E. coli concentrations did not differ between groups. 3GC r E. coli occurrences did not differ between control and CTC groups on any sampling occasion. For both groups, generic, TET r , and 3GC r E. coli occurrences were highest on 75 dpt and 117 dpt, suggesting that factors other than in-feed CTC contributed more significantly to antimicrobial-resistant E. coli occurrence. IMPORTANCEThe occurrence of human bacterial infections resistant to antimicrobial therapy has been increasing. It has been postulated that antimicrobial resistance was inevitable, but the life span of the antimicrobial era has been prematurely compromised due to the misuse of antimicrobials in clinical and agricultural practices. Direct evidence relating the use of antimicrobials in livestock production to diminished human health outcomes due to antimicrobial resistance is lacking, and the U.S. Food and Drug Administration has taken an approach to maximize therapeutic efficacy and minimize the selection of resistant microorganisms through judicious use of antimicrobials. This study demonstrated that prophylactic in-feed treatment of chlortetracycline administered for 5 days to calves entering feedlots is judicious, as this therapy reduced animal morbidity, reduced the use of antimicrobials more critical to human health, and had no long-term impact on the occurrence of antimicrobial-resistant E. coli.