Purpose Here, we investigated the genetic relationships and characteristics of extended- spectrum beta-lactamase-producing Escherichia coli (ESBL- E. coli ) isolates from healthy hosts, humans in the community and swine among the livestock of Amphor Mueang, Lamphun Province, Thailand. Patients and methods Four hundred and nine rectal swabs were collected from healthy people and swine. A total of 212 ESBL- E. coli was isolated and phenotypically confirmed by a combination disk method. Putative ESBL-encoding genes, including bla CTX-M , bla TEM , and bla SHV , were examined by multiplex-PCR. Randomly selected 42 ESBL- E. coli isolates were whole genome sequenced to characterize the ESBL-encoding genes and identify additional antimicrobial resistance genes. The genetic relatedness of 212 ESBL- E. coli was investigated by multilocus sequence typing. Results Overall, bla CTX-M was the dominant ESBL-encoding gene found in 95.75% of the isolates, followed by bla TEM (60.85%) and bla SHV (2.40%). While bla CTX-M-55 was the most common bla ESBL subgroup found in this study. Whole genome sequencing showed a total of 15 different antimicrobial resistance genes other than bla ESBL , including sul, qnr, aph(3ʹ)-Ia , among the selected 42 ESBL- E. coli isolates. Over half of the ESBL- E. coli (56.60%) carried bla CTX-M co-existing with bla TEM . The most common sequence types (STs) identified from human isolates were ST131, ST101, and ST70 while those isolated from swine were ST10, ST48, and ST131. ST131 strains carrying bla CTX-M were the major isolated ESBL- E. coli strains, supporting a previous study that considered this strain truly pathogenic. Noticeably, 66.51% of ESBL- E. coli strains shared 19 identical STs, including a host-restricted ST131 between humans and swine, suggesting that transmission between these two hosts might be possible. Conclusion Proof of a direct transfer of ESBL- E. coli from animals to humans, or vice versa, is required for further elucidation. The ESBL- E. coli isolated from both types of healthy hosts may serve as a reservoir for community-acquired antimicrobial resistance.

BackgroundColistin has been used for therapy of carbapenem-resistant Gram-negative infections in Thailand, especially carbapenem-resistant A. baumannii and P. aeruginosa, for more than 10 years. However, the prevalence of colistin-resistant A. baumannii or P. aeruginosa is still less than 5%. Colistin-resistant Enterobacteriaceae has been increasingly reported globally over the past few years and the use of colistin in food animals might be associated with an emergence of colistin resistance in Enterobacteriaceae. This study aimed to determine the effect of colistin exposure in hospitalized patients who received colistin on development of colistin-resistant (CoR) Escherichia coli (EC) or Klebsiella pneumoniae (KP) colonization and infection.MethodsA prospective observational study was performed in adult hospitalized patients at Siriraj Hospital who received colistin for treatment of infections during December 2016 and November 2017. The surveillance culture samples were collected from the stool and the site of infection of each patient who received colistin at the study enrollment, days 3 and 7 after the study enrollment, and once a week thereafter for determination of CoR EC and CoR KP. CoR EC and CoR KP were also tested for a presence of mcr-1 gene.ResultsOne hundred thirty-nine patients were included. Overall prevalence of CoR EC or CoR KP colonization was 47.5% among 139 subjects. Prevalence of CoR EC or CoR KP colonization was 17.3% of subjects at study enrollment, and 30.2% after study enrollment. Use of fluoroquinolones, aminoglycosides, and colistin was found to be significantly associated with CoR EC or CoR KP colonization. The mcr-1 gene was detected in 13.0% of CoR EC or CoR KP isolates, and in 27.3% of subjects with CoR EC or CoR KP colonization. CoR EC or CoR KP colonization persisted in 65.2% of the subjects at the end of the study. Five patients with CoR KP infections received combination antibiotics and they were alive at hospital discharge.ConclusionsPrevalence of CoR EC or CoR KP colonization in hospitalized patients receiving colistin was high and it was associated with the use of colistin. Therefore, patients who receive colistin are at risk of developing CoR EC or CoR KP colonization and infection.

BackgroundColonization with multidrug-resistant (MDR) bacteria is a major risk factor for developing subsequent MDR infections.MethodsWe performed a prospective surveillance study in hospitalized patients at Siriraj Hospital. Nasal cavity, throat, inguinal area and rectal swabs were obtained within the first 48-h after admission, on day-5 after hospitalization and then every 7 days until discharge. Target bacteria included extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL), carbapenem-resistant-P.aeruginosa (CR-PA), carbapenem-resistant-A.baumannii (CR-AB) and methicillin-resistant S.aureus (MRSA).ResultsFrom January 2013–December 2014, 487 patients were enrolled. The baseline prevalence of colonization by ESBL, CR-PA, CR-AB and MRSA at any site was 52.2%, 6.8%, 4.7% and 7.2%, respectively. After 3-week of hospitalization, the prevalence of colonization by ESBL, CR-PA, CR-AB and MRSA increased to 71.7%, 47.2%, 18.9% and 18.9%, respectively. Multivariable analysis revealed that diabetes mellitus and recent cephalosporin exposure were the independent risk factors for baseline colonization by ESBL. The independent risk factors for CR-AB and/or CR-PA colonization were cerebrovascular diseases, previous hospitalization, transfer from another hospital/a LTCF and previous nasogastric tube use, whereas those for MRSA colonization were previous fluoroquinolone exposure and previous nasogastric tube use.ConclusionsThe baseline prevalence of colonization by ESBL was relatively high, whereas the baseline prevalence of colonization by CR-PA, CR-AB and MRSA was comparable to previous studies. There was an increasing trend in MDR bacteria colonization after hospitalization.

Background Increasing awareness of and understanding about antimicrobial resistance (AMR), promoting changes in behavior, and monitoring of AMR in the community are challenging, as AMR is associated with many contributing factors that are difficult to assess individually. This study aimed to determine the effectiveness of a community-based AMR campaign for improving awareness, understanding, and behavior relating to antibiotic use and AMR in Thailand and to assess if fecal carriage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae could be a proxy composite indicator of AMR in the community. Methods This study was conducted in 4 communities that are home to approximately 400 000 people. A self-administered questionnaire on awareness, understanding, and behavior relating to antibiotic use and AMR was responded to by 20 521 and 19 634 adults before and immediately after the AMR campaign, respectively, at the household level. Fecal samples were collected from 534 adults before the AMR campaign and from 709 adults at 18 months after the AMR campaign to determine presence of ESBL-producing Enterobacteriaceae. Results Awareness, understanding, and behavior relating to antibiotic use and AMR, as assessed by a self-administered questionnaire, were significantly improved after the AMR campaign. The fecal carriage rate of ESBL-producing Enterobacteriaceae decreased from 66.5% before to 44.6% after the AMR campaign (P < .01). Conclusions Our AMR campaign was effective for improving awareness, understanding, and behavior relating to antibiotic use and AMR among people in the community at the household level, and the prevalence of fecal carriage of ESBL-producing Enterobacteriaceae seemed to be decreased after the AMR campaign. Fecal carriage rate of ESBL-producing Enterobacteriaceae may be a proxy composite indicator of AMR in the community.

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Objective: To investigate the extent of antibiotic-resistant bacteria and antibiotic residue contamination in fresh raw foods sold at wholesale markets in Thailand, which may be the important drivers of antibiotic-resistant bacteria colonization and antibiotic-resistant bacterial infection in Thai population. Materials and Methods: Fresh raw foods, including food from animal products, seafoods, vegetables, fruits, and honey were purchased from two large wholesale markets in Thailand. Food samples were cultured for antibiotic-resistant bacteria and tested for the presence and amount of antibiotic residue. Results: Among 521 samples for bacterial culture, 86.9% grew at least one kind of bacteria. Enterobacteriaceae were commonly isolated and were commonly resistant to ampicillin (76.7% to 100%). ESBL-producers and ceftriaxone-resistant Enterobacteriaceae were prevalent in swine and duck samples (56.7% to 91.7%). Some isolates were resistant to co-amoxiclav (13.3% to 60.0%) and cefoxitin (5.0% to 30.0%). Colistin-resistant Enterobacteriaceae were observed in pork meat (1.4%) and chicken offal (7.0%). Ertapenem-resistant Enterobacteriaceae were detected in cha-om (26.7%). Among 501 samples for antibiotic residue testing, 37.1% contained at least one antibiotic residue. Enrofloxacin was the most prevalent antibiotic residue, followed by doxycycline and tilmicosin. Although most samples contained less antibiotics than the maximum residue limit (MRL), 7.0% contained an amount of at least one antibiotic above the MRL. Conclusion: Many fresh raw foods sold at wholesale markets in Thailand were contaminated with antibiotic-resistant bacteria, and some contained antibiotic residues. Therefore, Thai people are at risk of being colonized with antibiotic-resistant bacteria and developing antibiotic-resistant bacterial infection due to consuming foods contaminated with antibiotic-resistant bacteria or containing antibiotic residues. Keywords: antibiotic-resistant bacteria, antibiotic residue, fresh raw foods, wholesale market, Thailand