[Prevalence and Antimicrobial Resistance of Campylobacter jejuni/coli and Analysis of Macrolide Resistance Isolates from Retail Meat in Tokyo, Japan (2010-2019)].

This study aimed to investigate the prevalence and antimicrobial sensitivity of Campylobacter jejuni and Campylobacter coli in retail meat (chicken, beef, pork, venison, wild boar, horse, lamb and mutton) in Tokyo (Japan) from 2010 to 2019. Furthermore, the resistance mechanism of erythromycin (EM)-resistant strains was analysed. C. jejuni had a highly positive rate in domestic chicken meat (53.4%, 334/626 samples), domestic chicken offal (49.3%, 34/69 samples), and domestic beef offal (28.3%, 47/166 samples), while C. coli had a high positivity rate in domestic pork offal (31.7%, 44/139 samples). The positive rate of C. jejuni was significantly higher in offal than that in meat in domestic beef, while the positive rate of C. coli was significantly higher in offal than that in meat in domestic beef and domestic pork (p<0.05). In the isolates, 1.0% (6/631 strains) of C. jejuni and 36.2% (55/152 strains) of C. coli were EM resistant, with 41.5% (262/631 strains) of C. jejuni and 65.1% (99/152 strains) of C. coli being ciprofloxacin resistant. A2075G mutation of the 23S rRNA gene was confirmed in all EM-resistant strains.

[Salmonella Serovars Isolated from Retail Meats in Tokyo, Japan and Their Antimicrobial Susceptibility].

To identify the risk of Salmonella in meat, we investigated the prevalence of Salmonella, serovars and their antimicrobial susceptibility patterns. Salmonella was found in 353 out of 849 (41.6%) chicken, 9 out of 657 (1.4%) pork, 1 out of 517 (0.2%) Beef, 6 out of 8 (75.0%) chicken offal, 43 out of 142 (30.3%) pork offal and 4 out of 198 (2.0) beef offal samples collected from retail meats in Tokyo, Japan between 2009 and 2017. Salmonella Infantis was the most common serovar, followed by S. Schwarzengrund in the isolates from domestic chicken meats. The prevalence rate of S. Infantis decreased while that of S. Schwarzengrund increased by the year. Apart from this, the most prevalent serovars were S. Heidelberg in the imported chicken meat isolates, S. Typhimurium and Salmonella O4:i:- in pork, and S. Derby in beef isolates. Antimicrobial testing revealed high resistance to tetracycline (TC) in all meat sample isolates; however, all the isolates were sensitive to carbapenem and fluoroquinolone. Fourteen cefotaxime (CTX) resistant strains, seven extended spectrum ß-lactamase (ESBL) producing strains and twenty-three AmpC producing strains were isolated from chicken meat samples. These findings indicate that the serovar and antimicrobial susceptibility varied among meat samples.

[Prevalence of Cereulide-Producing Bacillus cereus in Pasteurized Milk].

To recognize the risk of Bacillus cereus in pasteurized milk, we investigated the prevalence of B. cereus and the rate of the production of cereulide from B. cereus isolates. B. cereus was found in 66 out of 101 (65.3%) domestically pasteurized milk samples in Japan. The ces gene was identified in 3 out of 90 B. cereus isolates that were isolated from three samples (one product) among the 101 samples. The ces gene positive isolate, the reference strain F4810/72 and a B. cereus isolate collected in a food poisoning incident were shown the productivity of cereulide using an LC-MS/MS analysis. The LC-MS/MS analysis was confirmed the ability of identification and quantification of cereulide produced in the milk samples. In this study, it was shown that B. cereus strains are prevalent in pasteurized milk, some of these strains produce cereulide, and confirmed usefulness of LC-MS/MS analysis to detect cereulide in milk.

[Prevalence of Antimicrobial Resistance in Escherichia coli Isolated from Retail Meat in Tokyo, Japan].

This study aimed to survey the trend of antimicrobial resistance in Escherichia coli obtained from retail meat. We examined the susceptibilities of 1,115 E. coli isolates obtained from chicken, beef, pork, venison, and wild boar meat from 2011 to 2017 in Tokyo to 14 antimicrobials (ampicillin, cefotaxime (CTX), streptomycin, gentamicin, kanamycin, tetracycline (TC), chloramphenicol, nalidixic acid, ciprofloxacin, sulfamethoxazole-trimethoprim, fosfomycin, amikacin, imipenem, and meropenem). Of all the tested isolates, 18.7% (135/721) isolates from chicken, 77.0% (117/152) from beef, 46.6% (89/187) from pork, 100% (28/28) from venison, and 92.6% (25/27) from wild boar meat were susceptible to all tested antimicrobials. Furthermore, TC resistance was the most common, with rates as high as 56.7% (409/721) and 40.6% (76/187) in the isolates from chicken and pork, respectively. CTX resistance was detected in 4.9% (25/506) of the isolates from domestic chicken and 23.7% (51/215) of the isolates from imported chicken. Moreover, CTX resistance rate in isolates from domestic chicken was significantly lower in 2016 (0.9%, 1/111) and in 2017 (0.8%, 1/121) than in 2012 (10.6%, 17/161). In conclusion, E. coli isolates from retail meat were most commonly resistant to TC, and CTX resistance was higher in E. coli isolates from imported chicken than in E. coli isolates from domestic chicken.

Detection of the mcr-1 gene in colistin-resistant Escherichia coli from retail meat in Japan.

In this study, the presence of the mcr-1 gene in Escherichia coli from retail meat in Japan was investigated. Nine E. coli isolates (eight from chickens and one from pork) carried the mcr-1 gene on the plasmid. In six isolates from domestic chickens, mcr-1 was located on the IncI2 plasmid, which is approximately 60 kb in size. In the remaining three isolates from imported chicken and pork, mcr-1 was located on the IncX4 plasmid (30 kb).

Prevalence and contamination levels of listeria monocytogenes in ready-to-eat foods in Tokyo, Japan.

We surveyed prevalence and contamination levels of Listeria monocytogenes in ready-to-eat foods between 2000 and 2012 in Tokyo. L. monocytogenes was isolated from 52 (1.7%) out of 2,980 samples. Comparing the prevalence in the study period, 2.2% were positive in the former period (2000-2005) and 1.2% in the latter (2006-2012). Using the most probable number (MPN) technique, 32 samples were contaminated with fewer than 0.3 L. monocytogenes/g, 10 samples with 0.3-1.0/g and 4 samples with more than 1.0/g (the maximum was 2.3/g). The most common serovar was 1/2a, followed by 1/2b, 4b and 1/2c. We revealed that ready-to-eat foods in Tokyo were contaminated with L. monocytogenes, although the contamination levels were low.

Multiplex PCR serogrouping of Listeria monocytogenes isolated in Japan.

PCR serogrouping methods were used to examine strains of L. monocytogenes isolated in Japan. Among 187 strains, 99.5% were classified into 4 PCR serogroups corresponding to conventional serotypes. Only one isolate had a new PCR profile, which may be a variant of serogroup IVb.