Molecular Epidemiology, Microbial Virulence, and Resistance of Carbapenem-Resistant Enterobacterales Isolates in a Teaching Hospital in Guangzhou, China.

Infection caused by carbapenem-resistant Enterobacterales (CRE) is a global public health problem. We performed whole-genome sequencing to investigate the molecular epidemiological characteristics of local CRE infections and understand the prevalence of hypervirulent carbapenem-resistant Klebsiella pneumoniae (CRKP). Analysis of multiLocus sequence typing (MLST), antibiotic resistance genes, plasmid replicons, virulence genes, and the genetic environment was also performed. Klebsiella pneumoniae (89, 60.95%) was the most common CRE species, primarily prevalent in the intensive care unit (36, 40.45%). Most CRE strains showed a high resistance rate to multiple antibiotics, especially cephalosporins and carbapenems. However, most of these isolates were susceptible to tigecycline (81.7%). Notably, the predominant sequence type (ST) of CRKP isolates was ST11 (80.90%, 72/89), with 93.05% as Klebsiella pneumoniae carbapenemase (KPC)-ST11. In Escherichia coli isolates, ST410 (21.43%, 6/28) was the predominant type, with approximately half carrying blaNDM-5, and importantly, the ST167 carbapenem-resistant Escherichia coli (CRECO) harbors both New Delhi metallo-ß-lactamase (NDM)-5 and KPC-2. In Enterobacter cloacae isolates, three cases of ST88 were carrying the blaNDM-1 gene, and the ST594 carbapenem-resistant Enterobacter cloacae (CRECC) carrying NDM-1 and KPC-2 has also been identified. In addition, we found three novel STs, ST5386-ST5388. The IncFII (pHN7A8) (98.41%, 62/63) was the most common plasmid replicon type in KPC-2-producing CRKP strains, and the predominant plasmid ST of IncF was [f33:A-:B-] (n = 73). Two CRKP isolates were found to carry 4 virulence genes (iutA, iroB, rmpA, and rmpA2). As concluded, among CRKP strains, ST11 was the predominant ST with blaKPC-2, and a large proportion of CRKP strains co-harbor blaKPC-2, blaSHV, blaCTX-M, blaTEB-1B, and fosA. The predominant carbapenemase genes carried by CRECO and CRECC were blaNDM-1 and blaCTX-M, respectively.

Emergence of Clinical Pseudomonas aeruginosa Isolate Guangzhou-PaeC79 Carrying crpP, blaGES-5, and blaKPC-2 in Guangzhou of China.

As a potential "Superbug," Pseudomonas aeruginosa remains the leading concern in antimicrobial resistance. In this study, the emergence of clinical P. aeruginosa isolate was found to carry crpP and blaGES-5 on the chromosome and blaKPC-2 on a plasmid. A clinical P. aeruginosa strain Guangzhou-PaeC79 with an extensively drug-resistant phenotype was isolated, which was resistant to all classes of clinical commonly used antibiotics. It contains one chromosomal DNA and one plasmid, with seven acquired antimicrobial resistance genes identified on the chromosome, including carbapenem resistance gene blaGES-5 and fluoroquinolone resistance gene crpP, and carbapenem resistance gene blaKPC-2 located on an IncP-6-type plasmid pPAEC79 carrying a Tn3-like element. Carriage of any two of the resistance genes has never been previously reported, and simultaneous carriage of three bla and crpP may explain the bacterial phenotype as high-level resistance to imipenem and meropenem (≥16 µg/mL) and resistance to ciprofloxacin and levofloxacin.

Integron mediated bacterial resistance and virulence on clinical pathogens.

Integron was recognized as mobile elements responsible for the emergence and diffusion of antibiotic resistance, virulence and pathogenicity. The existence of resistant integron in pathogens may consequently lead to the increasing number of clinical failures in bacterial mediated diseases, as well as the expenses. In this study, a total of 22 clinical pathogens (including E. faecalis, S. aureus, K. pneumoniae, Enterobacter, P. aeruginosa and Acinetobacter) were subjected to the identification of class 1-class 3 integrons and drug resistant gene cassettes by high flux LAMP method. According to the results, the clinical isolates were screened as carrying class 1 integron with dfrA12-orfF-aadA2 cassette array, class 1 integron with dfrA17-aadA5 cassette array, class 1 integron with aadA2 cassette, class 1 integron with blaVIM2 cassette, class 1 and class 2 integron with dfrA1-sat1-aadA1 and dfrA12-orfF-aadA2 cassette arrays simultaneously, which was accordantly with the previous data. The optimized high flux LAMP assay was proceeded in water bath at 65 °C for 60 min and determined by naked eye, with the time consumption restricted within 2.5 h. Prior to conventional PCR method, the high flux LAMP assay was demonstrated as a highly-specific and highly-sensitive method. This study offered a valid LAMP method in resistance integrons detection for laboratory use, which was time-saving and easy-determination.