Prevalence, Antibiotic Resistance, and Molecular Typing of Staphylococcus aureus Isolated from Ready-to-Eat Foods in Guangdong, South China.

The increasing global popularity of ready-to-eat (RTE) foods for their convenience simultaneously brings along a risk, as these products can be contaminated with various microorganisms, including potentially harmful pathogens. We aimed to investigate the food contamination of Staphylococcus aureus (S. aureus) in RTE foods in Guangdong, South China. All S. aureus isolates were subjected to characterization through antimicrobial susceptibility tests, multilocus sequence typing (MLST), and PCR analysis for detecting mec and blaZ genes. A total of 824 RTE food samples were collected from 2017 to 2022, of which 73 (8.9%) were found to be contaminated with S. aureus. Contamination levels were mostly in the range of 0.3-1.0 most probable number (MPN)/g, with 10 samples exceeding 110 MPN/g. Of the 73 S. aureus isolates, 10 were identified as methicillin-resistant S. aureus (MRSA). In MRSA, resistance was most frequently observed to penicillin (100%, 10/10), followed by erythromycin (80.0%, 8/10) and tetracycline (70%, 7/10). And in methicillin-sensitive S. aureus (MSSA), resistance was most frequently observed to penicillin (98.4%, 62/63), followed by tetracycline (30.2%, 19/63) and erythromycin (23.8%, 15/63). Overall, 98.6% (72/73) of the isolates demonstrated resistance to at least one antimicrobial agent, whereas 31.5% (23/73) were resistant to three or more antimicrobials. Fifty-seven S. aureus isolates harbored the penicillin-resistant gene blaZ, and 10 isolates carried the mec gene. In addition, 30.1% of the isolates harbored genes for classical staphylococcal enterotoxins (SEs), with seb being the most frequently detected SE gene. MLST revealed that the 73 isolates belonged to 14 different sequence types (STs), the most prevalent of which was ST7. In MRSA, the most common prevalent clone is ST6, and in MSSA, ST7 was the most common isolates. The prevalent multidrug resistance indicates that the resistance situation of foodborne S. aureus in Guangdong is severe, posing a potential threat to consumer safety and health.

Characterization of Extended Spectrum Β-Lactamase Producing Enterobacteria and Methicillin-Resistant Staphylococcus aureus Isolated from Raw Pork and Cooked Pork Products in South China.

In this study, we assessed the co-colonization with extended spectrum ß-lactamase producing Enterobacteria (ESBL-E) and methicillin-resistant Staphylococcus aureus (MRSA) in raw pork and cooked pork products in south China. In total, 240 raw pork and 240 cooked pork samples collected from supermarkets (n = 20) and local butcher shops (n = 20) in the city of Guangzhou (China) were investigated. Raw pork and cooked pork was more frequent colonization with ESBL-E (7.5% in raw pork and 0.4% in cooked pork products) than with MRSA (4.2% in raw pork). Two of samples were contaminated with both tested types of multidrug-resistant bacteria. High antibiotic-resistance rate with wide spectrums of both ESBL-E and MRSA isolated were observed. In ESBL-E isolates, TEM (n = 15), CTX-M-1 (n = 3), CTX-M-9 (n = 1), and SHV (n = 1) genes were detected. TEM and SHV genes were associated with CTX-M-1 in 2 isolates, respectively. The CTX-M-9 gene of 1 isolate from cooked pork samples was found to be transferred to Escherichia coli J53 by conjugation. Detected MLST-types of MRSA were livestock-associated ST7 (n = 5) and ST9 (n = 4), as well as hospital-acquired ST239 (n = 1), suggesting contamination from human source(s) during meat processing. These findings confirmed a contamination of raw pork and cooked pork with ESBL-E and MRSA and emphasized the necessity of enforcing hygienic practices and specific detection of MRSA and ESBL-producing bacteria in meat processing and storage.

Prevalence and characterization of drug-resistant tuberculosis in a local hospital of Northeast China.

OBJECTIVES: To investigate the distribution and risk factors associated with drug-resistant tuberculosis (TB) at a local hospital in Northeast China. METHODS: A total of 205 patients with TB were enrolled in the study from March 8, 2010 to July 13, 2011. Mycobacterium tuberculosis (MTB) strains isolated from patients were subjected to drug susceptibility testing by proportion method. RESULTS: Among the 205 patients with MTB, 54 (26.3%) had isolates that showed resistance to at least one drug. The overall prevalence of multidrug-resistant TB (MDR-TB) was 6.8% (n = 14) (3.0% of newly diagnosed patients and 22.0% of previously treated cases). Importantly, an extensively drug-resistant TB (XDR-TB) isolate was found, which was isolated from a newly treated patient. Eleven (5.4%) were infected with a poly-resistant strain of MTB (5.5% of newly diagnosed patients and 4.9% of previously treated cases). The mono-resistance rates of isoniazid, rifampin, ethambutol, streptomycin, ofloxacin, and kanamycin were 3.4%, 1.5%, 2.4%, 3.9%, 2.4%, and 0.5%, respectively. Certain groups, including previously treated patients and male patients, were more likely to develop drug-resistant TB. CONCLUSIONS: The results of this analysis of drug resistance in MTB reflect the situation in a local hospital and indicate that the morbidity related to TB, especially MDR-TB, is still a serious health problem. Thus, the timely detection of drug resistance is of great importance to optimize treatment and to direct infection control measures to block the transmission of MDR-TB.