Detection and drug resistance profile of Escherichia coli from subclinical mastitis cows and water supply in dairy farms in Saraburi Province, Thailand

When the solution becomes the problem: a review on antimicrobial resistance in dairy cattle

Antibiotics' action, once a 'magic bullet', is now hindered by widespread microbial resistance, creating a global antimicrobial resistance (AMR) crisis. A primary driver of AMR is the selective pressure from antimicrobial use. Between 2000 and 2015, antibiotic consumption increased by 65%, reaching 34.8 billion tons, 73% of which was used in animals. In the dairy cattle sector, antibiotics are crucial for treating diseases like mastitis, posing risks to humans, animals and potentially leading to environmental contamination. To address AMR, strategies like selective dry cow therapy, alternative treatments (nanoparticles, phages) and waste management innovations are emerging. However, most solutions are in development, emphasizing the urgent need for further research to tackle AMR in dairy farms.

Knowledge, Attitude, and Practice of Thai Dairy Farmers on the Use of Antibiotics

Antibiotics have been used regularly in dairy farms by veterinarians; however, they were also used occasionally by farmers without any veterinary prescriptions. Because knowledge, attitude, and practice are important for sustainable antibiotic use, the levels of these aspects among farmers and associated factors should be determined to improve antibiotic use in dairy farming. The study was carried out in 89 Thai dairy farmers, using a structured questionnaire. Data were analyzed using descriptive statistics. The questions were scored and the total scores were calculated for each aspect. Factors associated with knowledge, attitude, and practice scores were identified using the multivariate linear regression. The mean scores for knowledge, attitude, and practice were 62%, 86%, and 78%, respectively. Higher education, participation in a training related to antibiotic use, and being supervised by the Veterinary Teaching Hospital Nong Pho were associated with a higher knowledge score (p < 0.050). Farmers with less experience received a higher attitude score (p = 0.020). Acquiring antibiotic knowledge from other farmers was associated with a lower practice score (p = 0.005). A positive association was found between knowledge and attitude scores (p = 0.021) and practice and attitude score (p < 0.001). Due to the insufficient knowledge on antibiotic use, there is a need to fill the gap to ensure prudent antibiotic use by farmers. Recommendations including training farmers by veterinarian to perceive the prudent antibiotic uses, encouraging young generation with higher education to participate in dairy farming, providing antibiotic use protocols, and decreasing the availability of antibiotics should be implemented to limit overuse by farmers.

Antibiograms, multidrug resistance, and milk-related parameters of bacteria isolated from milk of dairy cattle in Phatthalung, Thailand

Background and Aim

Milk, a nutritious food, is widely consumed in human diets; however, contamination by micro-organisms can negatively impact its quality and consumer health. Contamination by micro-organisms affects the quality of milk, which can affect the quality of the milk production chain. This study aimed to determine the changes in milk composition and antibiotic susceptibility related to bacteria isolated from dairy cow milk.

Materials and Methods

Raw milk samples were collected from 72 dairy cows. All milk samples were subjected to the California Mastitis Test (CMT) for CMT score determination. We also investigated milk composition, bacterial culture (BC), and antibiotic susceptibility.

Results

About 47.22% and 30.56% of dairy cattle were positive for CMT + BC and automatic somatic cell count (ASCC) + BC, respectively. Fecal appearance and animal age were found to be risk factors for ASCC + BC positivity in dairy cattle. Bacteria were found in approximately 76% of milk samples, with the most common isolated species being α-hemolytic Streptococcus spp., coagulase-negative Staphylococcus spp., and Escherichia coli. Of these, 70% are resistant to at least one antibiotic. Variation in the multidrug resistance pattern was high in Klebsiella spp.

Conclusions

Fecal appearance and animal age are risk factors for ASCC + BC positivity in dairy cattle. This study identified antibiotic and multidrug resistance patterns, which require comprehensive studies and effective surveillance systems. Remarkably, the use of antibiotic therapy in dairy cattle should be monitored.

Occurrence and molecular characteristics of antimicrobial resistance, virulence factors, and extended-spectrum β-lactamase (ESBL) producing Salmonella enterica and Escherichia coli isolated from the retail produce commodities in Bangkok, Thailand

The incidence of antimicrobial resistance (AMR) in the environment is often overlooked and leads to serious health threats under the One Health paradigm. Infection with extended-spectrum β-lactamase (ESBL) producing bacteria in humans and animals has been widely examined, with the mode of transmission routes such as food, water, and contact with a contaminated environment. The purpose of this study was to determine the occurrence and molecular characteristics of resistant Salmonella enterica (S. enterica) (n = 59) and Escherichia coli (E. coli) (n = 392) isolated from produce commodities collected from fresh markets and supermarkets in Bangkok, Thailand. In this study, the S. enterica isolates exhibited the highest prevalence of resistance to tetracycline (11.9%) and streptomycin (8.5%), while the E. coli isolates were predominantly resistant to tetracycline (22.5%), ampicillin (21.4%), and sulfamethoxazole (11.5%). Among isolates of S. enterica (6.8%) and E. coli (15.3%) were determined as multidrug resistant (MDR). The prevalence of ESBL-producing isolates was 5.1% and 1.0% in S. enterica and E. coli, respectively. A minority of S. enterica isolates, where a single isolate exclusively carried blaCTX-M-55 (n = 1), and another isolate harbored both blaCTX-M-55 and blaTEM-1 (n = 1); similarly, a minority of E. coli isolates contained blaCTX-M-55 (n = 2) and blaCTX-M-15 (n = 1). QnrS (11.9%) and blaTEM (20.2%) were the most common resistant genes found in S. enterica and E. coli, respectively. Nine isolates resistant to ciprofloxacin contained point mutations in gyrA and parC. In addition, the odds of resistance to tetracycline among isolates of S. enterica were positively associated with the co-occurrence of ampicillin resistance and the presence of tetB (P = 0.001), while the E. coli isolates were positively associated with ampicillin resistance, streptomycin resistance, and the presence of tetA (P < 0.0001) in this study. In summary, these findings demonstrate that fresh vegetables and fruits, such as cucumbers and tomatoes, can serve as an important source of foodborne AMR S. enterica and E. coli in the greater Bangkok area, especially given the popularity of these fresh commodities in Thai cuisine.

Atwill E, Jeamsripong S. Antimicrobial resistance, virulence profile, and genetic analysis of ESBL-producing Escherichia coli isolated from Nile tilapia in fresh markets and supermarkets in Thailand

This study investigated the prevalence and antimicrobial resistance (AMR) of Escherichia coli (E. coli) in Nile tilapia from fresh markets and supermarkets. A total of samples (n = 828) were collected from Nile tilapia including fish flesh (n = 276), liver and kidney (n = 276), and intestine (n = 276). Overall prevalence of fecal coliforms (61.6%) and E. coli (53.0%) were observed. High prevalence of E. coli was found in the intestine (71.4%), followed by the liver and kidney (45.7%). The highest prevalence of resistance was commonly found against tetracycline (78.5%), ampicillin (72.8%), and sulfamethoxazole (45.6%) with resistance to only tetracycline (15.2%) as the most common antibiogram. The prevalence of multidrug resistance (MDR) (54.4%) and Extended-spectrum beta-lactamases (ESBLs) (5.7%) were examined. The predominant virulence genes (n = 158) were st (14.6%), followed by eaeA (0.6%). The blaTEM (73.4%), tetA (65.2%), and qnrS (57.6%). There is statistical significance between Nile tilapia from fresh markets and supermarkets. Based on logistic regression analysis, ampicillin-resistant E. coli was statistically associated with the phenotypic resistance to tetracycline and trimethoprim, and the presence of blaTEM and tetA (p < 0.05). Further investigation of AMR transference and their mechanisms is needed for AMR control.

Isolation of bacteriophages specific to bovine mastitis-causing bacteria and characterization of their lytic activity in pasteurized milk

Background and Aim

Bovine mastitis is one of the most serious issues in dairy production. It is caused by contagious and coliform pathogens such as Staphylococcus spp., Escherichia coli, and Klebsiella pneumoniae. In addition, the emergence of drug-resistant bacteria raises urgent concerns in the field of drug treatment, thus requiring the exploration of alternative treatments. Bacteriophage therapy has been shown to be a promising alternative approach for the control of antibiotic-resistant pathogens. In this study, we aimed to isolate phages specific to contagious mastitis and coliform mastitis, characterize the isolated phages, and examine their ability to lyse bacteria in pasteurized milk samples.

Materials and Methods

The Staphylococcus phage vB_Sau-RP15 isolated from raw milk in our previous study was used in this study. Other three phages, vB_Eco-RN12i1, vB_Kpn-RN14i1, and vB_Ssc-RN20i3, were isolated from wastewater using E. coli 5823, K. pneumoniae 194, and Staphylococcus sciuri MM01 as hosts, respectively. The host range and efficiency of plating (EOP) were determined following phage isolation. Moreover, the lysis activities of these phages against their hosts were investigated in pasteurized milk using a multiplicity of infections (MOIs) of 10 and 100 at 37°C. Phages were applied using individual and combination phages.

Results

According to the EOP results, all phages showed high specificity to their respective hosts. They are tailed phages with distinct morphologies. Individual phage treatments in spiked pasteurized milk with their respective bacterial hosts significantly reduced the bacterial counts in both MOI conditions during the first 2 h of the treatment (approximately 1-8 log reduction compared to the control). Although these phages specifically infected only their hosts, the phage cocktail resulted in a better result compared to the use of individual phage. However, bacterial regrowth was observed in all experiments, which may be related to the development of phage-insensitive mutants.

Conclusion

Our findings suggest that the application of phages could be used to treat bovine mastitis. Phage cocktail is suitable to promote the efficacy of phage treatment in pasteurized milk. However, when considering the use of phages in dairy cows, certain phage properties in raw milk and in vivo and ex vivo should be highlighted to ensure their effectiveness as biocontrol agents for bovine mastitis treatment.

Draft genome sequence of multidrug-resistant Escherichia coli MAHK_SCM_BAU_30A strain isolated from a subclinical mastitis cow in Bangladesh

This study announces the sequence of a multidrug-resistant Escherichia coli MAHK_SCM_BAU_30A strain isolated from bovine subclinical mastitis milk in 2022 in Bangladesh. Our assembled genome had a length of 4,884,948 bp, three plasmids, two CRISPR arrays, five prophages, 51 predicted antibiotic resistance, and 72 predicted virulence factor genes.

Antimicrobial resistance in southeast Asian water environments: A systematic review of current evidence and future research directions

Antimicrobial resistance has been a serious and complex issue for over a decade. Although research on antimicrobial resistance (AMR) has mainly focused on clinical and animal samples as essential for treatment, the AMR situation in aquatic environments may vary and have complicated patterns according to geographical area. Therefore, this study aimed to examine recent literature on the current situation and identify gaps in the AMR research on freshwater, seawater, and wastewater in Southeast Asia. The PubMed, Scopus, and ScienceDirect databases were searched for relevant publications published from January 2013 to June 2023 that focused on antimicrobial resistance bacteria (ARB) and antimicrobial resistance genes (ARGs) among water sources. Based on the inclusion criteria, the final screening included 41 studies, with acceptable agreement assessed using Cohen's inter-examiner kappa equal to 0.866. This review found that 23 out of 41 included studies investigated ARGs and ARB reservoirs in freshwater rather than in seawater and wastewater, and it frequently found that Escherichia coli was a predominant indicator in AMR detection conducted by both phenotypic and genotypic methods. Different ARGs, such as blaTEM, sul1, and tetA genes, were found to be at a high prevalence in wastewater, freshwater, and seawater. Existing evidence highlights the importance of wastewater management and constant water monitoring in preventing AMR dissemination and strengthening effective mitigation strategies. This review may be beneficial for updating current evidence and providing a framework for spreading ARB and ARGs, particularly region-specific water sources. Future AMR research should include samples from various water systems, such as drinking water or seawater, to generate contextually appropriate results. Robust evidence regarding standard detection methods is required for prospective-era work to raise practical policies and alerts for developing microbial source tracking and identifying sources of contamination-specific indicators in aquatic environment markers.

Detection of AcrA and AcrB Efflux Pumps in Multidrug-Resistant Klebsiella pneumonia that Isolated from Wounds Infection Patients in Al-Diwaniyah Province

Many infections produced by multidrug-resistant (MDR) Klebsiella pneumoniae are the main cause of death and treatment restrictions worldwide. In K. pneumoniae, the efflux pump system is dangerous in drug resistance. Therefore, this study was designed to investigate the involvement of the AcrA and AcrB efflux pumps in antibiotic resistance in Klebsiella pneumoniae isolated from wound patients. During June 2021-February 2022, 87 clinical isolates of Klebsiella pneumonia bacteria were obtained from wound samples patients consulted to the hospitals in AL-Diwaniyah province, Iraq. The disc diffusion method performed an antibiotic susceptibility test after microbiological/biochemical identification. The polymerase chain reaction (PCR) technique was used to examine efflux genes' prevalence (acrA and acrB). The results showed that resistance to Carbenicillin 72 (82.7%), Erythromycin 66 (75.8%), Rifampin 58 (66.6%), Ceftazidime 52 (59.7%), Cefotaxime 44 (50.5%), Novobiocin 38 (43.6%), Tetracycline 32 (36.7%), Ciprofloxacin 22 (25.2%), Gentamicin 16 (18.3%), Nitrofurantoin 6 (10.3%) in Klebsiella pneumoniae isolates. The PCR procedure revealed that the occurrence of the acrA and acrB genes is 55 (100%) and 55 (100%), respectively. The findings of this investigation show that the AcrA and AcrB efflux pumps play a crucial character in antibiotic resistance in multidrug-resistant Klebsiella pneumoniae bacterial isolates. As a result of the unintentional transmission of antimicrobial resistance genes, precise detection of resistance genes using molecular approaches is required to switch the extent of resistant strains.

Invited review: Antimicrobial resistance in bovine mastitis pathogens: A review of genetic determinants and prevalence of resistance in European countries

Antimicrobial resistance is an urgent and growing problem worldwide, both for human and animal health. In the animal health sector actions have been taken as concerns grow regarding the development and spread of antimicrobial resistance. Mastitis is the most common infection in dairy cattle. We aimed to summarize the genetic determinants found in staphylococci, streptococci, and Enterobacteriaceae isolated from mastitic milk samples and provide a comparison of percentage resistance to a variety of antimicrobials in European countries.

Prevalence and Characterization of Serratia marcescens Isolated from Clinical Bovine Mastitis Cases in Ningxia Hui Autonomous Region of China

Purpose

This study aimed to investigate the prevalence and genetic characterization of Serratia marcescens isolates from clinical bovine mastitis in Ningxia Hui Autonomous Region of China.

Methods

S. marcescens was identified by the polymerase-chain reaction of 16S rRNA gene and sequencing. Antimicrobial susceptibility was tested by the disk diffusion method. Genes of resistance and virulence were determined by the PCR.

Results

Overall, S. marcescens were confirmed from 32 of 2897 (1.1%) mastitis milk samples. These isolates showed high resistance to cefazolin (30/32, 93.8%) and chloramphenicol (28/32, 87.5%). A 12.5% (4/32) of the isolates displayed multidrug resistance (MDR). The most prevalent resistant genes found in S. marcescens were TEM (32/32, 100%) and CTX-M (24/32, 75.0%; CTX-M-15, 14/32, 43.8%; CTX-M-14, 8/32, 25.0%; CTX-M-65, 2/32, 6.3%) for extended-spectrum beta-lactamase, cmlA (28/32, 87.5%) and floR (16/32, 50.0%) for chloramphenicol resistance, SIM-1 (2/32, 6.3%) for carbapenemases, and sdeB (28/32, 87.5%), sdeY (26/32, 81.3%), sdeR (26/32, 81.3%) and sdeD (20/32, 62.5%) for efflux pumps. Moreover, all isolates carried virulence genes flhD, entB, and kpn, and most of them contained mrkD (30/32, 93.8%), ycfM (26/32, 81.3%), bsmB (26/32, 81.3%), pigP (26/32, 81.3%), kfu (24/32, 75.0%) and shlB (24/32, 75.0%).

Conclusion

To our knowledge, this is the first report of genetic determinants for antimicrobial resistance and virulence in S. marcescens isolated from bovine mastitis cases in China. These findings are useful for developing strategies for prevention and treatment of bovine mastitis caused by S. marcescens in China.

Antimicrobial resistance, Extended-Spectrum β-Lactamase production and virulence genes in Salmonella enterica and Escherichia coli isolates from estuarine environment

The impact of antimicrobial resistance (AMR) on global public health has been widely documented. AMR in the environment poses a serious threat to both human and animal health but is frequently overlooked. This study aimed to characterize the association between phenotype and genotype of AMR, virulence genes and Extended-Spectrum β-Lactamase (ESBL) production from estuarine environment. The Salmonella (n = 126) and E. coli (n = 409) were isolated from oysters and estuarine water in Thailand. The isolates of Salmonella (96.9%) and E. coli (91.4%) showed resistance to at least one antimicrobial agent. Multidrug resistance (MDR) was 40.1% of Salmonella and 23.0% of E. coli. Resistance to sulfamethoxazole was most common in Salmonella (95.2%) and E. coli (77.8%). The common resistance genes found in Salmonella were sul3 (14.3%), followed by blaTEM (11.9%), and cmlA (11.9%), while most E. coli were blaTEM (31.5%) and tetA (25.4%). The ESBL production was detected in Salmonella (1.6%, n = 2) of which one isolate was positive to blaTEM-1. Eight E. coli isolates (2.0%) were ESBL producers, of which three isolates carried blaCTX-M-55 and one isolate was blaTEM-1. Predominant virulence genes identified in Salmonella were invA (77.0%), stn (77.0%), and fimA (69.0%), while those in E. coli isolates were stx1 (17.8%), lt (11.7%), and stx2 (1.2%). Logistic regression models showed the statistical association between resistance phenotype, virulence genes and ESBL production (p < 0.05). The findings highlighted that estuarine environment were potential hotspots of resistance. One Health should be implemented to prevent AMR bacteria spreading.

Phylogenetic analysis and antibiotic resistance of Escherichia coli isolated from wild and domestic animals at an agricultural land interface area of Salaphra wildlife sanctuary, Thailand

Background and Aim

Domestic and wild animals are important reservoirs for antibiotic-resistant bacteria. This study aimed to isolate Escherichia coli from feces of domestic and wild animals at an agricultural land interface area of Salaphra Wildlife Sanctuary, Thailand, and study the phylogenic characteristics and antibiotic resistance in these isolates.

Materials and Methods

In this cross-sectional, descriptive study, we randomly collected ground feces from free-ranging wild animals (deer and elephants) and domestic animals (cattle and goats). All fecal samples were inoculated onto MacConkey agar plates, and lactose-fermenting colonies were identified as E. coli. Antibiotic susceptibility of the E. coli isolates was determined using the disc diffusion method. Polymerase chain reaction assays were used to detect antibiotic resistance and virulence genes.

Results

We obtained 362 E. coli isolates from the collected fecal samples. The E. coli isolates were categorized into four phylogenetic groups according to the virulence genes (chuA, vjaA, and TspE4C2). Phylogenetic Group D was predominant in the deer (41.67%) and elephants (63.29%), whereas phylogenetic Group B1 was predominant in the cattle (62.31%), and phylogenetic Groups A (36.36%) and B2 (33.33%) were predominant in the goats. Antibiotic susceptibility testing revealed that most antibiotic-resistant E. coli were isolated from domestic goats (96.96%). Among the 362 E. coli isolates, 38 (10.5%) were resistant to at least one antibiotic, 21 (5.8%) were resistant to two antibiotics, and 6 (1.66%) were resistant to three or more antibiotics. Ampicillin (AMP) was the most common antibiotic (48.48%) to which the E. coli were resistant, followed by tetracycline (TET) (45.45%) and trimethoprim-sulfamethoxazole (3.03%). One isolate from an elephant was resistant to five antibiotics: AMP, amoxicillin, sulfisoxazole, TET, and ciprofloxacin. Determination of antibiotic resistance genes confirmed that E. coli isolates carried antibiotic resistance genes associated with phenotypic resistance to antibiotics. Most antibiotic-resistant E. coli belonged to phylogenic Groups A and B1, and most non-resistant E. coli belonged to phylogenic Groups B2 and D.

Conclusion

Monitoring E. coli isolates from wild and domestic animals showed that all four phylogenic groups of E. coli have developed antibiotic resistance and are potential sources of multidrug resistance. High levels of antibiotic resistance have been linked to domestic animals. Our results support strengthening surveillance to monitor the emergence and effects of antibiotic-resistant microorganisms in animals.

Genetic and Antimicrobial Resistance Profiles of Mammary Pathogenic E. coli (MPEC) Isolates from Bovine Clinical Mastitis

Mammary pathogenic E. coli (MPEC) is one of the main pathogens of environmental origin responsible for causing clinical mastitis worldwide. Even though E. coli are strongly associated with transient or persistent mastitis and the economic impacts of this disease, the virulence factors involved in the pathogenesis of MPEC remain unknown. Our aim was to characterize 110 MPEC isolates obtained from the milk of cows with clinical mastitis, regarding the virulence factor-encoding genes present, adherence patterns on HeLa cells, and antimicrobial resistance profile. The MPEC isolates were classified mainly in phylogroups A (50.9%) and B1 (38.2%). None of the isolates harbored genes used for diarrheagenic E. coli classification, but 26 (23.6%) and 4 (3.6%) isolates produced the aggregative or diffuse adherence pattern, respectively. Among the 22 genes investigated, encoding virulence factors associated with extraintestinal pathogenic E. coli pathogenesis, fimH (93.6%) was the most frequent, followed by traT (77.3%) and ompT (68.2%). Pulsed-field gel electrophoresis analysis revealed six pulse-types with isolates obtained over time, thus indicating persistent intramammary infections. The genes encoding beta-lactamases detected were as follows: bla_TEM (35/31.8%); bla_CTX-M-2/bla_CTX-M-8 (2/1.8%); bla_CTX-M-15 and bla_CMY-2 (1/0.9%); five isolates were classified as extended spectrum beta-lactamase (ESBL) producers. As far as we know, papA, shf, ireA, sat and bla_CTX-M-8 were detected for the first time in MPEC. In summary, the genetic profile of the MPEC studied was highly heterogeneous, making it impossible to establish a common genetic profile useful for molecular MPEC classification. Moreover, the detection of ESBL-producing isolates is a serious public health concern.

Characterizing the antimicrobial resistance profile of Escherichia coli found in sport animals (fighting cocks, fighting bulls, and sport horses) and soils from their environment

Background and Aim

Antimicrobial resistance (AMR) is a significant threat to global health and development. Inappropriate antimicrobial drug use in animals cause AMR, and most studies focus on livestock because of the widespread use of antimicrobial medicines. There is a lack of studies on sports animals and AMR issues. This study aimed to characterize the AMR profile of E. coli found in sports animals (fighting cocks, fighting bulls, and sport horses) and soils from their environment.

Materials and Methods

Bacterial isolation and identification were conducted to identify E. coli isolates recovered from fresh feces that were obtained from fighting cocks (n = 32), fighting bulls (n = 57), sport horses (n = 33), and soils from those farms (n = 32) at Nakhon Si Thammarat. Antimicrobial resistance was determined using 15 tested antimicrobial agents - ampicillin (AM), amoxicillin-clavulanic acid, cephalexin (CN), cefalotin (CF), cefoperazone, ceftiofur, cefquinome, gentamicin, neomycin, flumequine (UB), enrofloxacin, marbofloaxacin, polymyxin B, tetracycline (TE), and sulfamethoxazole/trimethoprim (SXT). The virulence genes, AMR genes, and phylogenetic groups were also examined. Five virulence genes, iroN, ompT, hlyF, iss, and iutA, are genes determining the phylogenetic groups, chuA, cjaA, and tspE4C2, were identified. The AMR genes selected for detection were blaTEM and blaSHV for the beta-lactamase group; cml-A for phenicol; dhfrV for trimethoprim; sul1 and sul2 for sulfonamides; tetA, tetB, and tetC for TEs; and qnrA, qnrB, and qnrS for quinolones.

Results

The E. coli derived from sports animals were resistant at different levels to AM, CF, CN, UB, SXT, and TE. The AMR rate was overall higher in fighting cocks than in other animals, with significantly higher resistance to AM, CF, and TE. The highest AMR was found in fighting cocks, where 62.5% of their isolates were AM resistant. In addition, multidrug resistance was highest in fighting cocks (12.5%). One extended-spectrum beta-lactamase E. coli isolate was found in the soils, but none from animal feces. The phylogenetic analysis showed that most E. coli isolates were in Group B1. The E. coli isolates from fighting cocks had more virulence and AMR genes than other sources. The AMR genes found in 20% or more of the isolates were blaTEM (71.9%), qnrB (25%), qnrS (46.9%), and tetA (56.25%), whereas in the E. coli isolates collected from soils, the only resistance genes found in 20% or more of the isolates were blaTEM (30.8%), and tetA (23.1%).

Conclusion

Escherichia coli from fighting cock feces had significantly higher resistance to AM, CF, and TE than isolates from other sporting animals. Hence, fighting cocks may be a reservoir of resistant E. coli that can transfer to the environment and other animals and humans in direct contact with the birds or the birds' habitat. Programs for antimicrobial monitoring should also target sports animals and their environment.

Molecular Characterization and Antimicrobial Resistance of Pathogenic Escherichia coli Strains in Children from Wolaita Sodo, Southern Ethiopia

Introduction

Pathogenic Escherichia coli strains cause diarrheal infection in children due to their virulence factors. A nonanalytical observational study followed by a purposive sampling technique was conducted from October 2017 to June 2018, to determine the antimicrobial susceptibility patterns and molecularly detect pathogenic Escherichia coli strains in under-five children at Wolaita Sodo town using molecular and the Kirby-Bauer disc diffusion method.

Result

In the current investigation, out of 110 stool samples, Escherichia coli was isolated in 68 (61.8%) (95% CI: 52.1–70.9%). Out of 68 Escherichia coli isolates, 61.9% of Escherichia coli isolates were resistant, 9.4% were intermediately resistant, and 28.7% were susceptible. Among the antimicrobial agents, 91.2% of Escherichia coli isolates were highly sensitive to ciprofloxacin followed by norfloxacin (86.8%). Virulence genes were detected in 55.9% (38/68) (95% CI 52.1%–70.9%) of isolates. The following genes were detected: stx1 (6 (8.8%)), stx2 (4 (5.9%)), eaeA (5 (7.4%)), eaat (14 (20.5%)), and St (4 (5.9%)). Out of 68 Escherichia coli isolates, 43 (63.2%) isolates had shown multidrug resistance patterns. Furthermore, 11.8% of Escherichia coli isolates had shown resistance to eight different drugs. The multidrug resistance index value of Diarrheagenic Escherichia coli pathotypes was greater than or equal to 0.4, which indicates the high risk of resistance.

Conclusion

This study demonstrated important pathogenic Escherichia coli strains and multidrug resistance in isolates containing virulence genes. Wise use of antimicrobials and improving the hygienic practices amongst parents of children reduce its occurrence. Therefore, appropriate usage of antimicrobial agents should also be highly practiced in hospitals.

Map of Enteropathogenic Escherichia coli Targets Mitochondria and Triggers DRP-1-Mediated Mitochondrial Fission and Cell Apoptosis in Bovine Mastitis

Bovine mastitis seriously affects bovine health and dairy product quality. Escherichia coli is the most important pathogen in the environment and dairy products. Enteropathogenic Escherichia coli (EPEC) is a zoonotic pathogen, which seriously threatens the health of people and dairy cows. We recently reported that E. coli can induce endogenous apoptosis in bovine mammary epithelial cells. However, the mechanism of EPEC-damaged mitochondria and -induced bovine mastitis is unclear. In this study, we found that EPEC can induce DRP-1-dependent mitochondrial fission and apoptosis. This was verified by the application of Mdivi, a DRP-1 inhibitor. Meanwhile, in order to verify the role of the Map virulence factor in EPEC-induced bovine mastitis, we constructed a map mutant, complementary strain, and recombinant plasmid Map_His. In the present study, we find that Map induced DRP-1-mediated mitochondrial fission, resulting in mitochondrial dysfunction and apoptosis. These inferences were further verified in vivo by establishing a mouse mastitis model. After the map gene was knocked out, breast inflammation and apoptosis in mice were significantly alleviated. All results show that EPEC targets mitochondria by secreting the Map virulence factor to induce DRP-1-mediated mitochondrial fission, mitochondrial dysfunction, and endogenous apoptosis in bovine mastitis.

Synergistic Antibacterial and Anti-inflammatory Activities of Ocimum tenuiflorum Ethanolic Extract against Major Bacterial Mastitis Pathogens

Mastitis is the most prevalent global illness affecting dairy cows. This bacterial infection damages and inflames the udder tissues. Several plant extracts have demonstrated synergistic antibacterial activities with standard drugs in mastitis treatment. Scant information exists on Ocimum tenuiflorum L. This study evaluated the antibacterial activity of O. tenuiflorum extract and its interaction with antibacterial drugs against common mastitis pathogens including Staphylococcus aureus, coagulase-negative Staphylococci (CNS), Streptococcus agalactiae, and Escherichia coli. Anti-inflammatory activities in LPS-stimulated RAW264.7 macrophage cells were also studied. The O. tenuiflorum extract exhibited antibacterial activities against S. aureus, CNS, and S. agalactiae with minimum inhibitory concentration (MIC) ranging from 3.9 to 31.2 µg/mL and minimum bactericidal concentration (MBC) ranging from 15.6 to 500 µg/mL. Combinations of O. tenuiflorum with penicillin or amoxicillin-clavulanic acid showed synergistic effects against all tested strains but an additive effect with cefazolin and gentamicin. Pretreatment of the extract significantly decreased the expression of inflammatory molecules (IL-6, TNF-α, IL-1β, iNOS, COX-2, and PGE2) generated by LPS in macrophages. Results suggested O. tenuiflorum effectiveness against various Gram-positive mastitis bacteria, with the potential to reduce antibacterial doses and combat inflammation.

Development of multidrug-resistant Escherichia coli in some Egyptian veterinary farms

Background and Aim: Food of animal origin is considered a major source of foodborne diseases. In this context, multidrug-resistant (MDR) Escherichia coli pose a serious hazard to public health due to the consumption of food contaminated with antibiotics that are used for the treatment of various bacterial infections in farm animals. Therefore, this study aimed to determine the effect of the excessive use of antibiotics on the development of MDR E. coli strains in Egyptian poultry, dairy, and meat farms. Materials and Methods: A total of 1225 samples were randomly collected from poultry, dairy, and meat products intended for human consumption in different governorates. E. coli were isolated from the collected samples and subjected to biochemical identification and antibiotic sensitivity tests with antibiotics commonly used in human and veterinary medicine. Then, amoxicillin (AML)- and oxytetracycline (OT)-resistant E. coli isolates were subjected to a polymerase chain reaction test to detect the blaTEM and tetA genes, respectively. Results: E. coli were isolated from 132 out of 350, 148 out of 350, 177 out of 350, and 35 out of 175 poultry, milk, meat, and human samples, respectively. Most of the isolates expressed multidrug resistance, and resistance genes (blaTEM and tetA) were detected in all the tested AML- and OT-resistant E. coli isolates. Conclusion: Foods of animal origin may represent a source of MDR E. coli, which can be a major threat to public health.

Prevalence and Antimicrobial Resistance of Escherichia coli, Salmonella and Vibrio Derived from Farm-Raised Red Hybrid Tilapia (Oreochromis spp.) and Asian Sea Bass (Lates calcarifer, Bloch 1970) on the West Coast of Peninsular Malaysia

Antibiotics are widely used in intensive fish farming, which in turn increases the emergence of antimicrobial-resistant (AMR) bacteria in the aquatic environment. The current study investigates the prevalence and determines the antimicrobial susceptibility of E. coli, Salmonella, and Vibrio in farmed fishes on the west coast of Peninsular Malaysia. Over a period of 12 months, 32 aquaculture farms from the Malaysian states of Selangor, Negeri Sembilan, Melaka, and Perak were sampled. Both E. coli and Salmonella were highly resistant to erythromycin, ampicillin, tetracycline, and trimethoprim, while Vibrio was highly resistant to ampicillin and streptomycin. Resistance to the antibiotics listed as the highest priority and critically important for human therapy, such as colistin in E. coli (18.1%) and Salmonella (20%) in fish, is a growing public health concern. The multi-drug resistance (MDR) levels of E. coli and Salmonella in tilapia were 46.5% and 77.8%, respectively. Meanwhile, the MDR levels of E. coli, Salmonella, V. parahaemolyticus, V. vulnificus and V. cholerae in Asian seabass were 34%, 100%, 21.6%, 8.3% and 16.7%, respectively. Our findings provide much-needed information on AMR in aquaculture settings that can be used to tailor better strategies for the use of antibiotics in aquaculture production at the local and regional levels.

Genome-wide association study on milk production and somatic cell score for Thai dairy cattle using weighted single-step approach with random regression test-day model

Genome-wide association studies are a powerful tool to identify genomic regions and variants associated with phenotypes. However, only limited mutual confirmation from different studies is available. The objectives of this study were to identify genomic regions as well as genes and pathways associated with the first-lactation milk, fat, protein, and total solid yields; fat, protein, and total solid percentage; and somatic cell score (SCS) in a Thai dairy cattle population. Effects of SNPs were estimated by a weighted single-step GWAS, which back-solved the genomic breeding values predicted using single-step genomic BLUP (ssGBLUP) fitting a single-trait random regression test-day model. Genomic regions that explained at least 0.5% of the total genetic variance were selected for further analyses of candidate genes. Despite the small number of genotyped animals, genomic predictions led to an improvement in the accuracy over the traditional BLUP. Genomic predictions using weighted ssGBLUP were slightly better than the ssGBLUP. The genomic regions associated with milk production traits contained 210 candidate genes on 19 chromosomes [Bos taurus autosome (BTA) 1 to 7, 9, 11 to 16, 20 to 21, 26 to 27 and 29], whereas 21 candidate genes on 3 chromosomes (BTA 11, 16, and 21) were associated with SCS. Many genomic regions explained a small fraction of the genetic variance, indicating polygenic inheritance of the studied traits. Several candidate genes coincided with previous reports for milk production traits in Holstein cattle, especially a large region of genes on BTA14. We identified 141 and 5 novel genes related to milk production and SCS, respectively. These novel genes were also found to be functionally related to heat tolerance (e.g., SLC45A2, IRAG1, and LOC101902172), longevity (e.g., SYT10 and LOC101903327), and fertility (e.g., PAG1). These findings may be attributed to indirect selection in our population. Identified biological networks including intracellular cell transportation and protein catabolism implicate milk production, whereas the immunological pathways such as lymphocyte activation are closely related to SCS. Further studies are required to validate our findings before exploiting them in genomic selection.

Bacteria from bovine clinical mastitis showed multiple drug resistance

Mastitis, which often manifests as udder infection in dairy animals, is of great concern as it affects public health and results in heavy economic losses to the dairy industry. A hospital-based cross-sectional study was conducted to determine the cultivable bacterial species associated with bovine clinical mastitis and their resistance patterns towards different antimicrobials. The milk samples from cows suffering from clinical mastitis during monsoon season were investigated. The prevalence of clinical mastitis was significantly high in Holstein-Friesian crossbred cows, followed by in Jersey crossbred, Red Kandhari and Deoni. Significantly high prevalence was observed during 4th to 6th months of lactation. A total of 110 bacterial isolates belonging to 14 different genera were isolated and identified. Aminoglycosides and quinolones were found to be the most effective antibiotics. Vancomycin resistant penicillinase producing Gram positive bacteria were demonstrated. Gram negative bacteria resistant to extended spectrum β lactamases, cephalosporins, tetracyclines, vancomycin and chloramphenicol as well as vancomycin resistant enterococci, multiple drug resistant (MDR) gram negative rods, MDR Pseudomonas and MDR Acinetobacter were found. Widespread resistance of Streptococcus uberis towards cephalosporins was documented. Variable MDR patterns were recorded within a single species. MDR transfer from non-pathogens to emerging foodborne and established mastitis pathogens could be a potential problem to the dairy industry as well as to public health.

Prevalence, Antimicrobial Susceptibility, and Molecular Characterization of Escherichia coli Isolated From Raw Milk in Dairy Herds in Northern China

Escherichia coli is a common bacterium in the intestines of animals, and it is also the major important cause of toxic mastitis, which is an acute or peracute disease that causes a higher incidence of death and culling of cattle. The purpose of this study was to investigate E. coli strains isolated from the raw milk of dairy cattle in Northern China, and the antibacterial susceptibility of these strains and essential virulence genes. From May to September 2015, 195 raw milk samples were collected from 195 dairy farms located in Northern China. Among the samples, 67 (34.4%) samples were positive for E. coli. About 67 E. coli strains were isolated from these 67 samples. The prevalence of Shiga toxin-producing E. coli (STEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), and enteroinvasive E. coli (EIEC) were 9, 6, 4.5, and 1.5%, respectively. Among the virulence genes detected, stx1 was the most prevalent (6/67, 9%) gene, followed by eae (3/67, 4.5%), and estB (2/67, 3%). Moreover, the strains exhibited different resistance levels to ampicillin (46.3%), amoxicillin-clavulanic acid (16.4%), trimethoprim-sulfamethoxazole (13.4%), tetracycline (13.4%), cefoxitin (11.9%), chloramphenicol (7.5%), kanamycin (7.5%), streptomycin (6.0%), tobramycin (4.5%), azithromycin (4.5%), and ciprofloxacin (1.5%). All of the E. coli isolates were susceptible to gentamicin. The prevalence of β-lactamase-encoding genes was 34.3% in 67 E. coli isolates and 45% in 40 β-lactam-resistance E. coli isolates. The overall prevalence of bla SHV, bla TEM, bla CMY, and bla CTX-M genes were 1.5, 20.9, 10.4, and 1.5%, respectively. Nine non-pathogenic E. coli isolates also carried β-lactamase resistance genes, which may transfer to other pathogenic E. coli and pose a threat to the farm's mastitis management projects. Our results showed that most of E. coli were multidrug resistant and possessed multiple virulence genes, which may have a huge potential hazard with public health, and antibiotic resistance of E. coli was prevalent in dairy herds in Northern China, and ampicillin should be used cautiously for mastitis caused by E. coli in Northern China.

Evidence-Based Tracking of MDR E. coli from Bovine Endometritis and Its Elimination by Effective Novel Therapeutics

Antibiotic-resistant bacteria have become the predominant etiology of endometritis and thus require effective treatment approaches. We used ultrasonography coupled with clinical signs and presented complaints of reproductive issues to investigate the epidemiology, phylogenetic analysis, antimicrobial resistance, and development of novel therapeutics against Escherichia coli isolated from endometritis in bovine (n = 304 from 10 commercial dairy farms). The prevalence of bovine endometritis in this study was 43.75%, while among these, 72.18% samples were positive for E. coli. Nucleotide analysis performed through BLAST and MEGAX showed 98% similarity to the nucleotide sequence of the reference E. coli strain (accession number CP067311.1). The disk diffusion assay revealed pathogen resistance to most antibiotics. Pattern of MIC order of resistance was as follows: enrofloxacin < gentamicin < co-amoxiclav < streptomycin < amoxicillin < metronidazole < oxytetracycline. Field trials revealed the highest recovery rate (in terms of clearance of endometritis and establishment of pregnancy) in case of gentamicin + enrofloxacin (100%) and gentamicin alone (100%), followed by co-amoxiclav + gentamicin (84.61%), oxytetracycline alone (78.57%), and metronidazole + enrofloxacin (33.33%). Hence, the current study reported a higher prevalence of multidrug-resistant E. coli showing considerable similarity with reference strain, and finally, the effective response of novel antibiotics to treat cases.

Prevalence and risk factors for multidrug-resistant Escherichia coli isolated from subclinical mastitis in the western Chitwan region of Nepal

Subclinical mastitis (SCM) represents a significant burden and challenge to modern dairy management. Multidrug-resistant Escherichia coli (MDR E. coli) in milk poses a public health threat to humans especially via the consumption of unpasteurized dairy products. This study aimed to determine the occurrence of MDR E. coli in cows and buffalo in the households of the western part of the Chitwan district of Nepal. A total of 243 lactating cows and buffalo were included in this study. Milk samples (n = 972) were screened using the California Mastitis Test (CMT). The E. coli was isolated from milk samples that were positive for CMT using standard bacteriological protocols. A semi-structured questionnaire was administered to farmers to identify the risk factors associated with the occurrence of SCM in cows and buffalo. Of the 243 dairy animals screened, 42.8% (n = 104/243) showed positive CMT results. However, of the 972 quarters sampled, only 19.3% (n = 188/972) were positive for SCM. The prevalence of E. coli in these animals was found to be 16.5% in animals (n = 40/243). However, E. coli was isolated from only 5% (n = 49/972) of the quarters. Of the 49 E. coli isolated, the resistance to ceftriaxone (38.8%, n = 19/49) and ciprofloxacin (37.7%, n = 17/49) were the most prevalent. Animals with a history of mastitis were 3.57 times more likely to have SCM than other animals. Similarly, lactating animals with previous teat abrasions were 3.22 times more likely to develop SCM than animals without teat injuries. As expected, cleaning the barn once in 2 to 3 d was associated with an increased occurrence of SCM in lactating cows. This study reports the occurrence of MDR E. coli in SCM, which poses a public health threat. Creating awareness of milk pasteurization, and food safety practices are necessary among the farmers.

Multidrug-resistant Escherichia coli in Raw Milk: Molecular Characterization and the potential impact of camel's Urine as an Antibacterial Agent

Raw milk is one of the most important vehicles for transmitting various pathogens, especially Escherichia coli (E. coli). Multidrug-resistant pathogens are highly prevalent among mastitic cows in various dairy farms worldwide. Therefore, our current study is based on the identification of E. coli from mastitic cow’s milk and their resistance to various antibacterial agents. As well, the impact of camel’s urine on multi-drug resistant E. coli were also evaluated. Thirty-three E. coli isolates were recovered from 254 milk samples. All strains were initially identified phenotypically by culturing on specific media and Vitek 2 Compact System. The protein fingerprinting technique was used as a confirmatory method. The Stx1, Stx2 and eae genes were also verified by polymerase chain reaction (PCR). The antimicrobial resistance of E. coli strains was tested by the Vitek 2 AST-GN69 cards. Thirty multi-drug resistant E. coli strains (20 from mastitic milk and 10 from clinical samples) were laboratory tested with different concentrations (100%, 75%, 50% and 25%) of virgin and breeding camel’s urine, using the paper disc diffusion method. Our findings showed that 93.94% of E. coli strains were recognized by the Vitek™ 2 system. The results of proteomic investigation illustrated that 100% of E. coli strains were identified at log values ≥2.00. The genotypic identification of the three virulence genes illustrated that 90.1%, 63.64%, and 30.55% of E. coli strains were able to carry the Stx1, eae, and Stx2 genes, respectively. Most strains of E. coli showed strong resistance against cefazolin (78.79%), ceftazidime (66.67%), cefotaxime (60.61%), ceftriaxone (54.55%), and cefepime (39.40%). The results of the antibacterial effect of camel’s urine revealed that the mean inhibitory zones of virgin camel’s urine were 28 mm, 17 mm, and 14 mm, for the concentrations of 100%, 75%, and 50%, respectively. Whereas; the inhibitory zones for the breeding camel’s urine were 18 mm, 0 mm, and 0 mm, for the concentrations of 100%, 75%, and 50%, respectively. We concluded that the majority of E. coli strains were able to harbor some virulence genes and resist many antibiotics. Our study also provided a robust evidence that the camel’s urine, particularly from the virgin camels has robust antimicrobial activity against multidrug-resistant E. coli strains.

Genes conferring anti­microbial resistance in cattle with subclinical mastitis

This study was carried out to evaluate the antimicrobial resistance (AMR) as a risk factor associated with some microorganisms isolated from subclinical mastitis (SCM) milk samples from Holstein Friesian dairy animals in Fayoum area, Egypt. The percentage of the SCM in the farm was found to be 41.18% and 63.88% at quarter and cows level respectively, with mean somatic cell count (SCC) of 8.8×105 ± 9.2×103 cells/mL and electrical conductivity (EC) 6.27 ± 0.066 mS/cm for SCM quarter milk samples. Out of the total 444 SCM cow milk samples, the most often isolated microorganisms were Staphylococcus aureus: 296 (66.6%), Enterococcus spp.: 230 (51.80%), Escherichia coli: 210 (47.29%) and Streptococcus agalactiae: 106 (23.87%). AMR was determined by disc diffusion test and the corresponding resistance genes were detected by PCR. Results of the in vitro susceptibility tests performed and the phenotypes indicated that the highest resistance to antibiotics for isolated microorganisms was against penicillin followed by amoxicillin + clavulanic acid, oxacillin and tetracycline, whereas moderate resistance was exhibited to oxytetracycline, ampicillin, sulfamethazole/trimethoprim, cefotaxime and erythromycin. However the most effective antibiotics against most isolates were nitrofurantoin and gentamicin followed by enrofloxacin, norfloxacin and cefoxitin. It was shown that the resistance to tetracyclines was due to the tetK or tetA(A) genes, the resistance to β-lactams (penicillins) – to blaZ and blaTEM genes, to macrolides (erythromycin): to ermB and ermC genes. Methicillin resistance genes were mecA, mec1 and mecC, glycopeptides (vancomycin) resistance gene was vanA, and norfloxacin resistance was attributed to norA gene.

Antimicrobial resistance of Escherichia coli isolated from retail foods in northern Xinjiang, China

To determine antimicrobial resistance, 431 samples of retail foods purchased at different supermarkets in Northern Xinjiang were examined in this study. There were 112 Escherichia coli strains that were isolated, with approximately 26% of the samples contaminated by E. coli. The detection rate of E. coli isolated from pork was the highest (59.6%), followed by mutton (52.6%), retail fresh milk (52.4%), duck (36.4%), beef (35.3%), chicken (33.3%), and ready-to-eat food (12.9%); the E. coli detection rate for fish and vegetables was <11%. The result showed that the 112 isolates were mostly resistant to tetracycline (52%), followed by ampicillin (42%), compound trimethoprim/sulfamethoxazole (37%), amoxicillin (33%), and nalidixic acid (32%), imipenem resistance was not detected. One hundred isolates carried at least one antimicrobial resistance gene. The detection rate of resistance genes of our study was as follows: tetA (38%), tetB (27%), bla OXA (40%), bla TEM (20%), floR (20%), sul1 (16%), sul2 (27%), aad Ala (19%), aadB (11%), strA (28%), and strB (24%); tetC and bla PSE were not detected. Virulence genes fimC, agg, stx2, fimA, fyuA, papA, stx1, and eaeA were found in 52, 34, 21, 19, 6, 3, 2, and 2 isolates, respectively; papC was not detected. There was a statistically significant association between fimC and resistance to ciprofloxacin (p = .001), gentamicin (p = .001), amikacin (p = .001), levofloxacin (p = .001), and streptomycin (p = .001); between fimA and resistance to tetracycline (p = .001), ampicillin (p = .001), compound trimethoprim/sulfamethoxazole (p = .001), and amoxicillin (p = .003); between agg and resistance to gentamicin (p = .001), tetracycline (p = .001), ciprofloxacin (p = .017), and levofloxacin (p = .001); and between stx2 and resistance to ampicillin (p = .001), tetracycline (p = .001), compound trimethoprim/sulfamethoxazole (p = .002), and amoxicillin (p = .015).

Bacterial Endotoxin Induces Oxidative Stress and Reduces Milk Protein Expression and Hypoxia in the Mouse Mammary Gland

The aim of this study was to investigate the mechanisms underlying the reduced milk production during mastitis. We hypothesized that bacterial endotoxin induces hypoxia, oxidative stress, and cell apoptosis while inhibiting milk gene expression in the mammary gland. To test this hypothesis, the left and right sides of the 4^th pair of mouse mammary glands were alternatively injected with either lipopolysaccharide (LPS, E. coli 055: B5, 100 μL of 0.2 mg/mL) or sterile PBS through the teat meatus 3 days postpartum. At 10.5 and 22.5 h postinjection, pimonidazole HCl, a hypoxyprobe, was injected intraperitoneally. At 12 or 24 h after the LPS injection, the 4^th glands were individually collected (n = 8) and analyzed. LPS treatment induced mammary inflammation at both 12 and 24 h but promoted cell apoptosis only at 12 h. Consistently, H₂O₂ content was increased at 12 h (P < 0.01), but dropped dramatically at 24 h (P < 0.01) in the LPS-treated gland. Nevertheless, the total antioxidative capacity in tissue tended to be decreased by LPS at both 12 and 24 h (P = 0.07 and 0.06, respectively). In agreement with these findings, LPS increased or tended to increase the mRNA expression of antioxidative genes Nqo1 at 12 h (P = 0.05) and SLC7A11 at 24 h (P = 0.08). In addition, LPS inhibited mammary expression of Csn2 and Lalba across time and protein expression of Csn1s1 at 24 h (P < 0.05). Furthermore, hypoxyprobe staining intensity was greater in the alveoli of the PBS-treated gland than the LPS-treated gland at both 12 and 24 h, demonstrating a rise in oxygen tension by LPS treatment. In summary, our observations indicated that while intramammary LPS challenge incurs inflammation, it induces oxidative stress, increases cell apoptosis and oxygen tension, and differentially inhibits the milk protein expression in the mammary gland.

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in cattle production - a threat around the world

Food producing animal is a global challenge in terms of antimicrobial resistance spread. Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are relevant opportunistic pathogens that may spread in many ecological niches of the One Health approach as human, animal and environment due to intestinal selection of antimicrobial resistant commensals in food production animals. Cattle production is a relevant ecological niche for selection of commensal bacteria with antimicrobial resistance from microbiota. Enterobacteriaceae show importance in terms of circulation of resistant-bacteria and antimicrobial resistance genes via food chain creating a resistance reservoir, setting up a threat for colonization of humans and consequent health risk. ESBL-producing Enterobacteriaceae are a threat in terms of human health responsible for life threatening outbreaks and silent enteric colonization of community populations namely the elder population. Food associated colonization is a risk difficult to handle and control. In a time of globalization of food trading, population intestinal colonization is a mirror of food production and in that sense this work aims to make a picture of ESBL-producing Enterobacteriaceae in animal production for food over the world in order to make some light in this reality of selection of resistant threats in food producing animal.

Prevalence of extended-spectrum β-lactamases in the local farm environment and livestock: challenges to mitigate antimicrobial resistance

The effectiveness of antibiotics has been challenged by the increasing frequency of antimicrobial resistance (AR), which has emerged as a major threat to global health. Despite the negative impact of AR on health, there are few effective strategies for reducing AR in food-producing animals. Of the antimicrobial resistant microorganisms (ARMs), extended-spectrum β-lactamases (ESBLs)-producing Enterobacteriaceae are an emerging global threat due to their increasing prevalence in livestock, even in animals raised without antibiotics. Many reviews are available for the positive selection of AR associated with antibiotic use in livestock, but less attention has been given to how other factors including soil, water, manure, wildlife, and farm workers, are associated with the emergence of ESBL-producing bacteria. Understanding of antibiotic resistance genes and bacteria transfer at the interfaces of livestock and other potential reservoirs will provide insights for the development of mitigation strategies for AR.

Detection of antimicrobial resistance genes of carbapenem-resistant Enterobacteriaceae in Escherichia coli isolated from the water supply of smallholder dairy farms in Saraburi and Maha Sarakham, Thailand

Background and Aim: The problem of antimicrobial resistance of bacteria in both humans and animals is an important public health concern globally, which is likely to increase, including in Thailand, where carbapenem-resistant Enterobacteriaceae (CRE), such as Escherichia coli, are of particular concern. They are pathogens found in the gastrointestinal tract of humans and other animals as well as in the environment. They may cause opportunistic infection and are often resistant to antibiotics in various fields especially in animal husbandry, such as pets or livestock farms. This study aimed to investigate the occurrence of carbapenem-resistant E. coli from water samples of smallholder dairy farms in Saraburi and Maha Sarakham, Thailand. Materials and Methods: Sixty-four water samples were collected from 32 dairy farms in Kaeng Khoi district, Muak Lek district, and Wang Muang district of Saraburi Province, and Kantharawichai district and Mueang district of Maha Sarakham Province, Thailand. All samples were cultured and isolated for E. coli by biochemical tests. All E. coli isolates were tested for drug susceptibility using imipenem, meropenem, and drug resistance genes of carbapenemases such as blaNDM, blaIMP, and blaOXA48 of drug-resistant E. coli isolates detected by polymerase chain reaction (PCR) technique. Results: A total of 182 E. coli isolates were found (140 and 42 isolates from Saraburi and Maha Sarakham, respectively). Drug sensitivity tests found that two isolates of E. coli from water in Kaeng Khoi were resistant to imipenem; therefore, the incidence of E. coli resistance to carbapenem was 1.43% of Saraburi Province. On the other hand, there was no incidence of drug-resistant E. coli in Maha Sarakham. In addition, the detection of the drug-resistant gene of E. coli in both isolates by PCR showed the expression of blaNDM. Conclusion: This study reports E. coli resistance to antimicrobial drugs on livestock farms. It can be considered to be the first report of E. coli CRE detection in a dairy farm at Saraburi, which should be the subject of further extended study.

Phenotypic antimicrobial susceptibility of environmental bacteria from mastitic milk of pastured dairy cows of S. Miguel (Azores)

The aim of this study was to evaluate the phenotypic (in vitro) antimicrobial susceptibility of milk pathogens isolated from subclinical and clinical mastitis in outdoor dairy herds of S. Miguel, Azores. Between January and March 2018, a total of 144 isolates was obtained from dairy cows with mastitis. Escherichia coli (38.9%; n = 56), Streptococcus uberis (20.1%; n = 29), and coagulase-negative staphylococci (17.4%; n = 25) were the major milk pathogens isolated. An in vitro average susceptibility of 52.0% was observed for 13 different antimicrobials (n = 725). According to an analysis of the mean for proportions, the proportions of bacterial isolates presenting in vitro susceptibility to danofloxacin (75.3%; P < 0.001) and to trimethoprim-sulfamethoxazole (25.0%; P < 0.05) were outside of the upper (65.8%) and lower (25.6%) decision lines, respectively. This profile was related to mainly with E. coli and Strep. uberis isolates. Multidrug resistance was observed in 2.1% isolates, namely, in two Strep. uberis strains from the same farm and one Enterococcus sp. strain. In conclusion, varying degrees of in vitro susceptibility of milk pathogens to the tested antimicrobials were observed, suggesting that these environmental bacteria probably play an important role in the spread of antimicrobial resistances in pastures. The use of fluoroquinolones to treat mastitis of dairy cows should be carefully evaluated in order to maintain their suitability for human medicine.

Epidemiological investigation of subclinical bovine mastitis in Algeria and molecular characterization of biofilm-forming Staphylococcus aureus

Thirty dairy farms were selected for this study; the first objective of our study was to investigate the prevalence of subclinical bovine mastitis (SCM) in Eastern Algeria, from 600 lactating cows, and to identify potential risk factors associated with the occurrence of bovine mastitis and bacteria isolation using logistic regression. The second objective was to evaluate biofilm formation capacity and detect biofilm-associated genes of S. aureus, isolated from SCM cases. Molecular typing was investigated by spa typing. The prevalence of mastitis at cow and quarter level was 37.66% (226/600) and 27.17% (555/2042), respectively. Stage of lactation, cow breed, milk production, and the study area were factors associated with SCM. In addition, the most frequent pathogens isolated from mastitic milk were coagulase-negative staphylococci (CNS), E. coli, and S. aureus. The study area was highly associated with SCM caused by S. aureus; cows from Setif province were 18 times more affected with SCM caused by S. aureus compared to cows from Batna province (OR = 18.6, 95%CI 2.038-171.2), but were less affected with SCM caused by CNS isolates (OR = 0.17, 95%CI 0.033-0.868). Moreover, cows with milk production less than 10 L per day increased (p < 0.05) the prevalence of mastitis caused by E. coli. All the S. aureus isolates had biofilm-forming ability, and 41.66% of isolates were positive for adhesion genes (icaA, icaD, fbnA, and clfA). This study, therefore, warrants the need for improving sanitary measures and strict hygienic measures, and presents the first insight into biofilm-forming ability of S. aureus strains causing mastitis in dairy herds in Algeria, which will help in tracking the evolution of epidemic strains responsible for causing bovine mastitis.

Antibiotic Susceptibility and Virulence Factors in Escherichia coli from Sympatric Wildlife of the Apuan Alps Regional Park (Tuscany, Italy)

Today a growing number of studies are focusing on antibiotic resistance in wildlife. This is due to the potential role of wild animals as reservoirs and spreaders of pathogenic and resistant bacteria. This study focused on isolating and identifying Escherichia coli from the feces of wild animals living in the Apuan Alps Regional Park (Tuscany, Italy) and evaluating some of their antibiotic resistance and pathogenicity traits. Eighty-five fecal samples from different species were studied. Seventy-one E. coli were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry analysis, subjected to antibiograms and polymerase chain reaction for the detection of antibiotic resistance genes and pathogenicity factors. The highest resistance rates were found against cephalothin (39.4%) and ampicillin (33.8%), followed by amoxicillin/clavulanic acid (15.5%), streptomycin (12.7%), and tetracycline (5.6%). Regarding resistance genes, 39.4% of the isolates were negative for all tested genes. The remaining isolates were positive for bla_CMY-2, sul2, strA-strB and aadA1, tet(B), and tet(A), encoding resistance to beta-lactams, trimethoprim/sulfamethoxazole, streptomycin, and tetracycline, respectively. With regard to virulence factors, 63.4% of the isolates were negative for all genes; 21.1% carried astA alone, which is associated with different pathotypes, 9.9% carried both escV and eaeA (aEPEC); single isolates (1.4%) harbored escV (aEPEC), escV associated with astA and eaeA (aEPEC), astA with stx2 and hlyA (EHEC) or astA and stx1, stx2, and hlyA (EHEC). These results show that wildlife from nonanthropized environments can be a reservoir for antibiotic-resistant microorganisms and suggest the need for a deeper knowledge on their origin and diffusion mechanisms through different ecological niches.

Shiga Toxin-Producing Escherichia coli in Mastitis: An International Perspective

The pathogen profile of Escherichia coli mastitis reveals a complex etiology involving commensal, environmental, and other distinct E. coli pathotypes such as enteropathogenic E. coli and of recent, Shiga toxin-producing E. coli (STEC) have been associated with bovine intramammary infections (IMI). Many researchers have not been testing for STEC and focused on E. coli detection without further subtyping, and as such, the prevalence of STEC in mastitis remains underdiagnosed and underreported. Owing to the dearth of information on STEC involvement in IMI, this review provides an international perspective on the prevalence of STEC in mastitis. In addition, predominant serotypes, ancillary virulence factors, and antimicrobial resistance profiles of STEC isolated from mastitis cases were summarized. This information is important for public health policy since STEC impact both animal health and human welfare. Importantly, the low infectious doses of STEC are a major concern to public health. The review highlights the need for further surveillance to ascertain the potential for environmental contamination and food chain security by STEC from bovine mastitis, and emphasizes appropriate, science-based mitigation approaches for prevention or control.

Characterisation and Antibiotic Resistance of Selected Bacterial Pathogens Recovered from Dairy Cattle Manure during Anaerobic Mono-Digestion in a Balloon-Type Digester

Dairy cattle manure serves as a potential source of contamination and infection of animals, humans and the environment. Manure samples withdrawn from a balloon-type digester during anaerobic digestion were evaluated for the presence of antibiotic-resistant bacterial pathogens. The bacterial load of the samples was determined via a viable plate count method and the recovered isolates were subjected to characterisation and identification. These isolates were employed in antibiotic susceptibility testing using a disc diffusion method against a suite of 10 conventional antibiotics. The multiple antibiotic resistance (MAR) index was calculated and MAR phenotypes were generated. Although all the bacterial pathogens showed a certain degree of resistance to the studied antibiotics, a marked resistance was demonstrated by Campylobacter sp. to co-trimoxazole (87.5%) and nalidixic acid (81.5%). Remarkably, a high resistance (82.42%) was demonstrated against the antibiotic class, macrolide, followed by beta-lactams (40.44%), suggesting that bacterial resistance depended on the chemical structure of the antibiotics. However, individual bacterial isolates varied in resistance to particular antibiotics. Of the 83 bacterial isolates, 40(48.19%) observed MAR > 0.2 and, thus, were described as multidrug-resistant isolates. A total of 28 MAR phenotypes were revealed with the highest frequency of MAR phenotypes (37.5%) expressed against 3 antibiotics. Results indicated a high risk of exposure to various antibiotics and wide diversity of antibiotic resistance.

Detection, characterization, and antibiogram of extended-spectrum beta-lactamase Escherichia coli isolated from bovine milk samples in West Bengal, India

Background:

Milk is considered as complete food and an important part of human diet throughout the world including India. Bacterial contamination of milk such as Escherichia coli due to unhygienic condition and poor udder health can cause infections, especially in infants and elders or in immunocompromised persons. Possession of antimicrobial resistance genes by commensal bacteria present in milk makes the issue more serious.

Aim:

The study was aimed to isolate and characterize extended-spectrum beta-lactamase (ESBL)-producing E. coli from milk samples collected from different parts of West Bengal, India, to assess the potential risk associated with the food.

Materials and Methods:

Around 182 milk samples were collected from apparently healthy cows reared by organized dairy farms in West Bengal. E. coli was isolated from collected samples as per standard methods followed by serotyping. The detection of ESBL-producing E. coli was done both phenotypically and genotypically by detecting the presence of bla_CTX-M gene. Antibiogram of the ESBL-positive isolates was done using common 12 antibiotics by disc diffusion method.

Results:

A total of 22 (12.1%) samples were found to be positive for E. coli in this study. Different serotypes such as O11, O20, O22, O34, O35, O128, O149, and UT were isolated from the collected samples. 12 (54.5%) E. coli strains showed the capability of producing ESBL, both phenotypically and genotypically with the presence of bla_CTX-M gene. Antibiogram of these ESBL-positive isolates revealed the drugs such as colistin (100%), levofloxacin (83.33%), and imipenem (66.67%) to be highly sensitive against this pathogen but drugs such as cefotaxime (100%), ceftazidime (91.67%), amoxicillin/clavulanic acid (83.33%), tetracycline (75.00%), and gentamicin (58.33%) to be very much resistant.

Conclusion:

More than 50% of the E. coli strains prevalent in the bovine milk samples were positive for ESBL production and are resistant to most of the common antimicrobials which may be alarming for human health.

Antibiotic Use in Agriculture and Its Consequential Resistance in Environmental Sources: Potential Public Health Implications

Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems). The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

Genomic Analysis of Third Generation Cephalosporin Resistant Escherichia coli from Dairy Cow Manure

The production of extended-spectrum β-lactamases (ESBLs) conferring resistance to new derivatives of β-lactams is a major public health threat if present in pathogenic Gram-negative bacteria. The objective of this study was to characterize ceftiofur (TIO)- or cefotaxime (FOX)-resistant Escherichia coli isolated from dairy cow manure. Twenty-four manure samples were collected from four farms and incubated under anaerobic conditions for 20 weeks at 4 °C or at 25 °C. A total of 37 TIO- or FOX-resistant E. coli were isolated from two of the four farms to determine their susceptibility to 14 antibiotics. Among the 37 resistant E. coli, 10 different serotypes were identified, with O8:H1 being the predominant serotype (n = 17). Five isolates belonged to each of serotypes O9:NM and O153:H42, respectively. All 37 cephalosporin resistant isolates were multi-resistant with the most prevalent resistance spectrum being amoxicillin-clavulanic acid-ampicillin-cefoxitin-ceftiofur-ceftriaxone-chloramphenicol-streptomycin-sulfisoxazole-tetracycline-trimethoprim-sulfamethoxazole. The genomes of 18 selected isolates were then sequenced and compared to 14 selected human pathogenic E. coli reference genomes obtained from public repositories using different bioinformatics approaches. As expected, all 18 sequenced isolates carried at least one β-lactamase bla gene: TEM-1, TEM-81, CTX-M115, CTX-M15, OXA-1, or CMY-2. Several other antibiotic resistance genes (ARGs) and virulence determinants were detected in the sequenced isolates and all of them harbored antimicrobial resistance plasmids belonging to classic Inc groups. Our results confirm the presence of diverse ESBL producing E. coli isolates in dairy cow manure stored for a short period of time. Such manure might constitute a reservoir of resistance and virulence genes for other bacteria that share the same environment.