Objective　To understand the contamination characteristics of Enterobacteriaceae, and the drug resistance, related drug resistance genes and genotypes of ESBLs-producing strains in ready-to-eat fresh-cut fruits and vegetables, so as to provide references not only for food safety of ready-to-eat fresh-cut fruits and vegetables, but also for the risk prevention and control of drug-resistant bacteria. Methods　In 2023, Common fresh-cut fruits and vegetables samples were collected from markets in Hainan. Quantitative detection of Enterobacteriaceae bacteria was performed, with enrichment in enteric bacterial enrichment broth and selective isolation using ESBL chromogenic medium. ESBLs-producing antibiotic-resistant Enterobacteriaceae strains were then identified and their drug resistance to antibiotics was analyzed using VITEK 2 Compact automatic microbial identification system. The related drug-resistant genes were detected by PCR, the PCR-positive products were sequenced to determine the resistance genotypes. Results　Among the 427 samples of ready-to-eat fresh-cut fruits and vegetables collected, the contamination levels of Enterobacteriaceae ranged from 1.30 to 6.86 lg CFU/g. Forty-nine strains of Klebsiella pneumoniae (contamination rate 11.48%, 49/427) and thirty-eight strains of Escherichia coli (contamination rate 8.90%, 38/427) were identified as ESBLs producers. These ESBLs-producing strains showed multiple drug resistance, with ESBLs-producing Klebsiella pneumoniae showing a 100.00% resistance rate to ampicillin and cefazolin (49/49); resistance rates to ceftazidime, ceftriaxone, and cefepime were 73.46% (36/49), 81.63% (40/49), and 73.46% (36/49), respectively; the resistance rate to trimethoprim-sulfamethoxazole was 79.59% (39/49). ESBLs-producing E. coli strains have 100% resistance to ampicillin, cefazolin, ceftazidime, ceftriaxone, and cefepime (38/38), with a resistance rate of 52.63% (20/38) to trimethoprim-sulfamethoxazole. Detection of resistance genes revealed that the β-lactam resistance gene blaCTX-M, the sulfonamide resistance gene sulII, and the mobile element integrase gene intI were detected in ESBLs-producing Klebsiella pneumoniae and Escherichia coli at rates of 57.14% (28/49) and 84.21% (32/38), 75.51% (37/49) and 68.42% (26/38), and 91.84% (45/49) and 86.84% (33/38), respectively. The β-lactam resistance genotypes included CTX-M-1, CTX-M-9, and TEM-1, while CTX-M-2, CTX-M-8, CTX-M-25, and SHV types were not detected. Conclusions　In 2023, ready-to-eat fresh-cut fruits and vegetables in Hainan were contaminated with Enterobacteriaceae producing ESBLs. There is a prevalent multidrug resistance in isolated strains of ESBLs-producing Klebsiella pneumoniae and Escherichia coli, presenting a high risk for resistance gene horizontal transmission. It is recommended to pay attention to the contamination of drug-resistant bacteria in ready-to-eat fresh-cut fruits and vegetables in the whole chain of "environment-food-human" to prevent them from becoming vectors for the spread of resistance genes through the food chain, posing a threat to human health.

Objective　To provide a data foundation not only for food safety supervision and pollution source tracing, but also for the clinical treatment of drug-resistant bacteria in barreled drinking water, the drug resistance and type Ⅲ secretion system (T3SS) virulence genes carriage of Pseudomonas aeruginosa detected in barreled drinking water in Hainan Province were investigated, and the correlative relationship between strain ribosomal subtypes and virulence genes were then discussed. Methods The drug resistance of the isolated 55 strains of Pseudomonas aeruginosa was confirmed by using VITEK 2 Compact automatic microbial drug sensitivity system, and the T3SS virulence genes ExoU, ExoS, ExoT and ExoY were amplified by PCR, bacterial strain subtypes and homology were analyzed by the RiboPrinter automatic microbial gene fingerprint identification system. Results The drug sensitivity results showed that Pseudomonas aeruginosa isolated from barreled water had relatively low drug resistance, though one strain of multidrug-resistant Pseudomonas aeruginosa was discovered, resistant to imipenem, ciprofloxacin and cefepime. The distribution of T3SS virulence genes showed four genotypic combinations: ExoT+/ExoY+/ExoS+/ExoU- (45.45%, 25/55), ExoT+/ExoY+/ExoS-/ExoU+ (34.55%, 19/55), ExoT+/ExoY-/ExoS-/ExoU+(18.18%, 10/55), ExoT+/ExoY+/ExoS+/ExoU+ (1.82%, 1/55). Ribosomal typing results showed that the Pseudomonas aeruginosa strains were divided into six subtypes, the numbers of each subtype accounted for 24 (43.64%), 1 (1.82%), 25 (45.45%), 1 (1.82%), 3 (5.45%) and 1 (1.82%) respectively, with subtype Ⅰ and subtype Ⅲ being dominant. The main T3SS genotypes of the top two subtype I and subtype III were ExoT+/ExoY+/ExoS-/ExoU+ (16/24, 66.67%) and ExoT+/ExoY+/ExoS+/ExoU- (22/25, 88%). Conclusions The T3SS secretion system exhibits the characteristics of multiple virulence genes' coordinated expression, and there is a certain correlation between subtypes of bacterial strains and virulence genotypesThe exploration of the relationship between them provides guidance for tracing the source of Pseudomonas aeruginosa contamination, production control, clinical treatment in barrelled drinking water, and preliminarily establishes the initial data of local Pseudomonas aeruginosa strains in barrelled drinking water as well the related drug sensitivity data in Hainan.