Staphylococcus aureus is responsible for large numbers of hospital-related and community-acquired infections. In this study, we investigated the presence of S. aureus and methicillin-resistant S. aureus (MRSA) in 100 samples from animals (55 cattle, 36 dogs, and 9 cats) and 150 samples from hospitalized human patients. The samples were collected from healthy and diseased animals and from diseased humans and included milk, wound swab, pus, exudates, nasal swab and diabetic ulcer. Initially, S. aureus was isolated and identified by colony morphology, Gram staining, and biochemical tests (catalase and coagulase tests). The S. aureus-positive samples were examined by polymerase chain reaction (PCR) to determine their MRSA status. Of the 100 animal samples, 29 were positive for S. aureus. Four samples (13.8%) from dogs were MRSA-positive, but samples from cattle and cats were MRSA-negative. Of the 150 human samples we collected, 64 were S. aureus-positive and, of these, 34 (53.1%) were MRSA-positive. Most (28%) of the MRSA samples were isolated from surgical wound swabs, followed by the pus from skin infections (11%), exudates from diabetic ulcers (6%), exudates from burns (4%), and aural swabs (3%). By contrast, a low MRSA detection rate (n = 4) was seen in the non-human isolates, where all MRSA bacteria were isolated from nasal swabs from dogs. The antimicrobials susceptibility testing results showed that S. aureus isolates with mecA genes showed resistance to penicillin (100%), oxacillin (100%), erythromycin (73.5%), ciprofloxacin (70.6%), and gentamicin (67.7%). The lowest resistance was found against ceftazidime, and no vancomycin-resistant isolates were obtained. We detected S. aureus and MRSA in both human and canine specimens. Isolates were found to be resistant to some of the antimicrobials available locally. MRSA carriage in humans and animals appears to be a great threat to effective antimicrobials treatment. The prudent use of antimicrobials will reduce the antimicrobial resistance. Our findings will help to find the most appropriate treatment and to reduce antimicrobial resistance in the future by implementing prudent use of antimicrobials. Further studies are required to better understand the epidemiology of MRSA human–animal inter-species transmission in Bangladesh.

Staphylococcal infection is one of the most common food-borne diseases in the world. Moreover, antimicrobial resistance of pathogenic bacteria, including Staphylococcus (S.) aureus is an emerging problem of food safety. This study was conducted to investigate the prevalence of S. aureus in milk, chicken meat, egg and beef; and to determine the multi-drug resistance (MDR) profile of S. aureus in Mymensingh and Gazipur districts, Bangladesh. A total of 189 samples of milk (n=108), chicken meat (n=51), egg (n=20) and beef (n=10) were collected from Bangladesh Agricultural University dairy farm, American dairy farm, Gazipur and different dairy farms of municipal area and retail shops during July 2016 to June 2018. S. aureus were isolated and identified by conventional methods and polymerase chain reaction (PCR). Antimicrobial susceptibility tests were done through disc diffusion test using 10 commonly used antibiotics. The overall prevalence of S. aureus in all food samples was 43.39%. A total of 39 (76.47%) chicken meat, 25 (23.15%) milk, 11(55%) egg and 07 (70%) beef samples were S. aureus positive through conventional method. Among 82 culture positive samples only 39 samples (47.56%) were confirmed by PCR. Antibiogram study showed that S. aureus isolated from chicken meat were mostly resistant to oxytetracycline (71.79%); and highly sensitive to amikacin (100%) and neomycin (100%). S. aureus isolated from milk samples were highly sensitive to neomycin (100%), and resistant to amikacin (56%). Only 28.57% isolates of S. aureus originated from beef samples were resistant to oxytetracycline and 100 % isolates were sensitive to ciprofloxacin, gentamicin, erythromycin, azithromycin, doxycycline. Similarly, S. aureus isolated from egg samples were resistant to erythromycin (81.82%) and 100% sensitive to amikacin. Out of 41.46% MDR isolates 12%, 53.85%, 90.91% and 0% of the S. aureus originated from milk, chicken meat, egg and beef respectively. The higher prevalence of S. aureus in chicken meat, beef, egg and milk indicates unhygienic production, marketing and processing of these foods. Presence of MDR S. aureus in these foods might pose serious public health threats. Rational use of antibiotics with higher sensitivity should be prescribed in managing poultry diseases to reduce re-emerging MDR in Bangladesh.Res. Agric., Livest. Fish.5(2): 175-183, August 2018

Bovine tuberculosis (bTb) is endemic in Bangladesh but the true prevalence has not yet been reported. Our objectives for this study were to determine the true prevalence and identify risk factors for bTb at the animal- and herd-level in Bangladesh. A total of 510 cows were randomly selected during January 2018 to December 2018. Caudal fold (CFT) and comparative cervical tuberculin tests (CCT) were serially interpreted. Animal- and herd-level risk factor data were collected using a pre-tested questionnaire. The hierarchical true prevalence of bTb was estimated within a Bayesian framework. The herd- and animal-level risk factors were identified using mixed effects logistic regression. The apparent prevalence of bTb was 20.6% [95% Confidence Interval (CI): 17.3; 24.3] based on CFT. The animal-level true prevalence of bTb was 21.9 (13.0; 32.4). The herd-level true prevalence in different regions varied from 41.9% to 88.8%. The region-level true prevalence was 49.9 (13.8; 91.2). There is a 100% certainty that herds from Bhaluka and Mymensingh Sadar upazilas are not free from bTb. The odds of bTb were 3.9 times (1.2; 12.6) higher in herds having more than four cows than those with ≤ 4 cows. On the other hand, the risk of bTb was 3.3 times higher (1.0; 10.5) in non-grazing cows than grazing cows. Crossbred cows were 2.9 times (1.5; 5.9) more likely to be infected with bTb than indigenous cows. The risk of bTb in animals with cough was 2.3 times (1.2; 4.3) higher than those without cough. Crossbred, non-grazing cows with cough should be targeted for bTb surveillance. Herds of the Mymensingh, Sadar and Bhaluka regions should be emphasized for bTb control programs. Estimation of Bayesian hierarchical true prevalence facilitates identification of areas with higher prevalence and can be used to indicate regions that where true prevalence exceeds a pre-specified critical threshold.

Methicillin-resistant Staphylococcus aureus (MRSA) is defined by the presence of the mecA gene, which is considered to have been transferred horizontally from unknown bacterial species to S. aureus . As a candidate of evolutionary precursor of the mecA , the mecA -like gene ( mecA homologue), which is ubiquitously present in Staphylococcus sciuri has been proposed. In this study, sequences of the mecA homologue in four S. sciuri strains (SCBM1–SCBM4) derived from dairy cows were determined to analyze their genetic characteristics and relatedness to mecA and the mecA homologue reported so far. The mecA -like gene sequences of the four S. sciuri strains were identical with each other and were considered to encode a product comprising 665 amino acids that is one amino acid smaller in size than products of mecA -like gene reported previously for S. sciuri strains K1, K11, and K3 ( mecA1 ). The mecA homologue of a representative strain SCBM1 showed 79.3–79.8% sequence identity to MRSA mecA and 93.4–94.4% identity to mecA homologues reported for the three S. sciuri strains. Between S. sciuri strain SCBM1 and strains K1, K11, or K3, amino acid sequence identities in transpeptidase domain of the mecA -like gene product (98.2–98.5%) were higher than those in the transglycosylase domain (92.1–94.3%). In addition, SCBM1 showed extremely high sequence identities of hsp60, sodA , and rpoB genes (more than 98.7%) to S. sciuri strains, while showing 70.3–94.2% identity of these genes to other staphylococcal species. These findings indicated that mecA homologues in S. sciuri may be genetically more divergent than mecA in MRSA and methicillin-resistant coagulase-negative staphylococci.

Bovine rotavirus (BRV) is considered the leading cause of calf diarrhea worldwide, including Bangladesh. In this study we aimed to identify risk factors for BRV infection and determine the G and P genotypes of BRV strains in diarrheic calves. Fecal samples were collected from 200 diarrheic calves in three districts between January 2014 and October 2015. These samples were screened to detect the presence of BRV using rapid test-strips BIO K 152 (RTSBK). The RTSBK positive samples were further tested by polyacrylamide gel electrophoresis and the silver staining technique to detect rotavirus dsRNA. Risk factors were identified by multivariable logistic regression analysis. The G and P genotypes of BRV were determined by RT-PCR and sequencing. A phylogenetic tree was constructed based on the neighbor-joining method using CLC sequence viewer 8.0. About 23% of the diarrheic calves were BRV positive. The odds of BRV infection were 3.8- (95% confidence interval [95% CI]: 1.0–14.7) and 3.9-times (95% CI:1.1–14.2) higher in Barisal and Madaripur districts, respectively, than Sirrajganj. The risk of BRV infection was 3.1-times (95% CI: 1.5–6.5) higher in calves aged ≤ 5 weeks than those aged >5 weeks. Moreover, the risk of BRV infection was 2.6-times (95% CI:1.1–5.8) higher in crossbred (Holstein Friesian, Shahiwal) than indigenous calves. G6P[11] was the predominant genotype (94.4%), followed by G10P[11] (5.6%). The BRV G6 strains were found to be closest (98.9–99.9%) to Indian strains, and BRV G10 strains showed 99.9% identities with Indian strain. The VP4 gene of all P[11] strains showed >90% identities to each other and also with Indian strains. The most frequently identified BRV genotype was G6P[11]. About 23% of calf diarrhea cases were associated with BRV. To control disease, high-risk areas and younger crossbred calves should be targeted for surveillance and management. The predominant genotype could be utilized as the future vaccine candidate or vaccines with the dominant genotype should be used to control BRV diarrhea in Bangladesh.

Background and Aim: The emergence of antimicrobial-resistant bacteria, such as Escherichia coli in milk, is a serious public health concern as milk is considered a complete food and an important part of daily human diet worldwide, including in Bangladesh. However, there have been no reports on the molecular characterization and antibiotic resistance profile of extended-spectrum beta-lactamase (ESBL)-producing E. coli from milk of healthy cows in Bangladesh. Therefore, this study aimed to detect and characterize ESBL-producing E. coli (ESBL-Ec) in milk samples from healthy cows in smallholder dairy farms in Mymensingh district, Bangladesh, and assess the potential risk of consuming this milk. Materials and Methods: A total of 100 milk samples were collected from apparently healthy cows on smallholder dairy farms. Escherichia coli was isolated from the collected samples using standard methods. The detection of ESBL-Ec was performed phenotypically using cultural methods and genotypically by ESBL genetic determinants using multiplex polymerase chain reaction. Antimicrobial susceptibility testing of the ESBL-Ec isolates was performed using the disk diffusion method with 15 common antimicrobials. Results: In this study, out of the 100 samples tested, 70 (70%) were found to be positive for E. coli. Among these, 41 (58.6%) strains were identified as ESBL-producing, both phenotypically and genotypically, with the presence of blaCTX-M, blaTEM, and blaSHV individually or combined (blaCTX-M plus blaTEM plus blaSHV). The antibiogram of these ESBL-positive isolates revealed high resistance against commonly used antibiotics, such as ampicillin, cefotaxime, and gentamicin (100%), azithromycin (88%), oxytetracycline (27%), nalidixic acid, cotrimoxazole/trimethoprim (24%), and streptomycin (22%). In addition, one isolate showed resistance to 4th generation of cephalosporin (cefepime). Most importantly, extensive multidrug resistance was found in many ESBL-Ec isolates. However, the isolates were highly sensitive to drugs such as ceftriaxone (100%) and imipenem (100%). This is the first study to detect ESBL-Ec in raw milk from healthy cows on smallholder dairy farms in Bangladesh. Conclusion: More than 58% of the E. coli isolated from raw milk of healthy cows tested positive for ESBL production and showed resistance to most commonly used antimicrobials which may be alarming for human health. A limitation of our study is that we had a small size of sample collected from one district in Bangladesh. Therefore, a larger sample size covering a wider geographic area, and using multi-locus sequence typing and whole genome sequencing could provide a more comprehensive understanding of the prevalence and characteristics of ESBL-Ec in Bangladesh. Keywords: ampicillin, antibiogram, blaCTX-M, cefotaxime, multiplex PCR, multidrug resistance.