Distribution and dissemination of antimicrobial-resistant Salmonella in broiler farms with or without enrofloxacin use

Abstract

BackgroundSalmonella is a major zoonotic food-borne pathogen that persists on poultry farms, and animals undergo reinfection with endemic strains. The present study aimed to investigate the characteristics and dissemination of antimicrobial-resistant Salmonella within and between broiler farms that used enrofloxacin and those that did not.ResultsCloacal and environmental (litter, feed, and water) samples from two selected flocks in each of 12 farms owned by the same company were collected three times over a 30-day period of two production cycles during 2015–2016. The rate of Salmonella isolation was 7.8% (123/1584). Nine Salmonella serotypes (116 isolates) and seven untypable isolates were identified, and Salmonella Montevideo was the most prevalent serotype. Azithromycin-resistant (17.9%) and colistin-resistant (3.3%) isolates were detected, and multidrug-resistant isolates (43.1%) were also observed. No isolate was resistant to enrofloxacin or ciprofloxacin; however, intermediate resistance to enrofloxacin was significantly higher (P < 0.05) in farms that used enrofloxacin than in those that did not. The rate of multi-drug resistance among litter isolates (25/44, 56.8%) was significantly higher (P < 0.05) than that among cloacal swab (24/67, 35.8%) and feed (4/12, 33.3%) isolates. Pulsed-field gel electrophoresis (PFGE) analysis of strains of the same serotype was conducted to determine their epidemiological relationship. The PFGE types were classified into 31 groups with a 100% correlation cutoff in dendrograms for Salmonella Montevideo isolates, which showed 100% genomic identity based on age, sample type, flock, and production cycle within and between farms.ConclusionThe present study highlights the occurrence of horizontal transmission and cyclic contamination with antimicrobial-resistant Salmonella in broiler farms owned by the same company. Litter may be a good indicator of indoor environmental contamination with antimicrobial-resistant Salmonella on farms. Additionally, enrofloxacin use may be one of the factors promoting resistance towards it in Salmonella.Electronic supplementary materialThe online version of this article (10.1186/s12917-018-1590-1) contains supplementary material, which is available to authorized users.

Antibiogram Profiles and Risk Factors for Multidrug Resistance of Salmonella enterica Recovered from Village Chickens (Gallus gallus domesticus Linnaeus) and Other Environmental Sources in the Central and Southern Peninsular Malaysia

“…The highest levels of resistance manifested by the isolates from the aforementioned studies were against tetracycline (100%), ampicillin (100%), clindamycin (100%), and ciprofloxacin (83%). Moreover our Salmonella isolates were susceptible to ciprofloxacin in contrast to that reported elsewhere as being between 30.8% and 96% [ 28 , 29 , 30 , 31 ].…”

“…These findings further support the role of the environment in the dissemination and recirculation of MDR Salmonella [ 49 , 50 ]. Shang et al (2018) found a significantly higher isolation rate of MDR Salmonella from litter samples compared to other samples in broiler farms, indicating the significance of poultry litters in the in-door environmental transmission of MDR Salmonella [ 31 ].…”

Prevalence of Multidrug Resistance Non-Typhoidal Salmonellae Isolated from Layer Farms and Humans in Egypt.

“…Antibiotic sensitivity test results presented in table 6 showed that some human isolates are 100% resistant to certain antibiotics such as neomycin and chloramphenicol, despite their limited use in the human field. This finding illustrates the pivotal role of poultry farms in transmitting the infection to humans (Shang et al, 2018). The results of the antibiotic sensitivity test suggested the guidelines for both physicians and veterinarians to select the relevant antibiotics to diminish antibiotic resistance among NTS which have industrial and public health significance.…”

Antimicrobial Resistance in Salmonella Serovars Isolated From an Egg-Producing Region in Brazil

“…In 2016, the use of colistin sulfate as a performance enhancer was banned in Brazil (Brasil, 2016) in order to prevent cross-resistance of pathogens of public health concern (Hu et al, 2017). Therefore, the identification of polymyxin E-resistant zoonotic Salmonella strains in layer farms in the present study is a matter of concern, as this drug is one of the last treatment choices for human salmonellosis, and resistance against broad-spectrum drugs may result in high mortality rates (Costa et al, 2013;Shang et al, 2018).…”

“…The 41% rate of ciprofloxacinresistant strains determined in the present study is in agreement with previous studies, which also found high incidence rates of resistant Salmonella spp., of 25.0% in Ghana (Andoh et al, 2017) and of 35.1% in Shanghai (Wei et al, 2019). These results are a matter of concern, as the emergence of such strains may lead to failure of the treatment of severe bacterial infections in human medicine (Costa et al, 2013;Shang et al, 2018).…”