Antimicrobials in small-scale urban pig farming in a lower middle-income country – arbitrary use and high resistance levels

Abstract

BackgroundAdministration of antimicrobials to food-producing animals is regarded as a major contributor to the overall emergence of resistance in bacteria worldwide. However, few data are available on global antimicrobial use and resistance (AMR) in livestock, especially from low- and middle-income countries.MethodsWe conducted a structured survey of 91 small-scale pig farms in the urban and peri-urban areas of Phnom Penh, Cambodia, to assess the farmers’ knowledge, attitudes and practices related to antimicrobial use in their pig production. Commensal Escherichia coli was isolated from three healthy pigs from each farm (n = 261) and susceptibility testing was performed against 14 antimicrobials, using broth microdilution. Univariable logistic regression and generalized linear mixed models were used to investigate potential associations between farm characteristics, management factors and resistance to different types of antimicrobials.ResultsWe found a widespread and arbitrary use of antimicrobials, often based on the farmer’s own judgment. Around 66% of the farmers reported frequently self-adjusting treatment duration and dosage, and 45% had not heard about the term ‘antimicrobial resistance’. The antimicrobials most commonly mentioned or kept by the farmers were amoxicillin, tylosin, gentamicin and colistin. Around 37% used a feed concentrate that contained antimicrobials, while antimicrobials for humans were used as a last-line treatment by 10% of the farmers. Commensal E. coli exhibited high prevalence of resistance to several antimicrobials considered to be of critical importance for human medicine, including ampicillin, ciprofloxacin and colistin, and multidrug-resistance was found in 79% of the samples. Higher prevalence of resistance was observed on farms that administered prophylactic antimicrobials and on farms that treated the entire group or herd in the event of disease.ConclusionThe widespread and arbitrary use of antimicrobials in pig farming in Cambodia is highly worrisome. Overall, farmers had a low awareness of the risks and consequences related to antimicrobial use and AMR. The results presented in this study confirm the hypothesis that non-rational use of antimicrobials results in higher prevalence of AMR and highlight the need for professional animal health systems that involve medically rational use of antimicrobials in emerging economies such as Cambodia.Electronic supplementary materialThe online version of this article (10.1186/s13756-018-0328-y) contains supplementary material, which is available to authorized users.

Carriage of carbapenemase‐ and extended‐spectrum cephalosporinase‐producing Escherichia coli and Klebsiella pneumoniae in humans and livestock in rural Cambodia; gender and age differences and detection of blaOXA‐48 in humans

“…Pigs were often kept in crowded confinement (Osbjer et al, ), which allows for frequent transmission of bacteria. Previous studies have found that antibiotic use in the pig and poultry industry in Cambodia is widespread and uncontrolled (Om & McLaws, ; Ström, Boqvist, et al, ). ESCE is also frequent in poultry production in Europe, even in countries with low antibiotic resistance burden, and the prevalence is mainly related to vertical transmission (Blaak et al, ; Borjesson et al, ).…”

“…A study on backyard chicken farms in Vietnam concluded that detection of mcr‐1 ‐carrying bacteria in chicken samples was associated with colistin use and that detection in human samples was associated with exposure to mcr‐1 ‐positive chickens (Trung et al, ). Through interviewing pig farmers in Cambodia, Ström, Boqvist, et al ()) found that antibiotic use, including colistin, was common in pig farms and sometimes used as prophylactic treatment.…”

“…Little is known about the situation in Cambodian livestock, but one study detected E. coli isolates harbouring bla TEM‐1 and bla CMY‐2 from faecal samples from five pigs in a Cambodian slaughterhouse (Trongjit, Angkittitrakul, & Chuanchuen, ). Interviews with pig farmers have revealed that antibiotic use was common in pig farms (Ström, Boqvist, et al, ). ESBL‐producing Salmonella has recently been isolated from retail meat in Phnom Penh, Cambodia, and most isolates were harbouring bla CTX‐M‐55 (Nadimpalli et al, ).…”

Meat and Fish as Sources of Extended-Spectrum β-Lactamase–Producing Escherichia coli, Cambodia

“…Approximately half of these colonization isolates had MLSTs detected among food, and a substantial portion were more likely to produce CTX-M-55 and be amphenicol resistant than colonization isolates that grouped separately. The fact that chloramphenicol has not been used in human medicine for almost 20 years in Cambodia, yet chloramphenicol analogs (e.g., florfenicol, thiamphenicol) are administered to food animals ( 5 , 7 ), suggests a food origin for these colonizing isolates.…”

“…High ESBL colonization rates in low- and middle-income countries such as Cambodia are usually attributed to unrestricted consumer access to and hospital overuse of third-generation cephalosporins ( 3 , 4 ). However, antimicrobial drugs in classes critical for human health (e.g., β-lactams, macrolides, aminoglycosides, polymyxins) are increasingly being used in food animals ( 5 ). In Cambodia, weak public health protections and consumption of undercooked animal products could exacerbate the spread of ESBL-producing E. coli or ESBL genes from animals to humans.…”