Antibiotic Resistance Determinants and Virulence Factors of Hypervirulent and Carbapenem Non-Susceptible Pseudomonas aeruginosa.

BACKGROUND: The aim was to investigate the distribution of antibiotic resistance determinants and virulence factors in a group of carbapenem non-susceptible Pseudomonas aeruginosa (P. aeruginosa). METHODS: From March 2018 to May 2019, a total of 98 P. aeruginosa samples were collected from 6 hospitals in Ningbo and Hangzhou, Zhejiang Province, China. Drug susceptibility tests to 13 antimicrobial agents were conducted. The presence of antibiotic resistance determinants and virulence factors were investigated by PCR, including 39 ß-lactamase genes, 14 aminoglycoside modifying enzyme genes, 10 16SrRNA methylase genes, and 11 virulence genes. Phylogenetics of 98 P. aeruginosa was analyzed by sample cluster analysis (UPGMA). RESULTS: PCR revealed the presence of 7 ß-lactamase genes, 5 aminoglycoside modifying enzymes, 1 16S rRNA methylase gene, and 8 virulence genes in total, at least 2 ß-lactamase genes and 4 virulence genes were positive in every isolate. In addition, regional differences in distributions of resistance and virulence genes remained between 2 cities. Sample cluster analysis showed that the strains had obvious aggregation and were divided into several clusters, strains in the same cluster were isolated from different hospitals, even from different cities. CONCLUSIONS: Carrying resistance genes blaPDC and blaOXA-50 group and virulence genes plcH, aprA, and algD were the important epidemiological characteristics of this group of P. aeruginosa. The present findings provide insights into the mechanisms of hypervirulence as well as resistance to ß-lactams and aminoglycosides. To the best of our knowledge, this is the first report of blaPDC, blaOXA-50, and aph(3')-XV in P. aeruginosa in China.

[Emergence of novel variants of gyrA, parC, qnrS genes in multi-drug resistant Klebsiella caused pneumonia].

OBJECTIVE: To investigate the resistant mechanism of quinolones on multi-drug resistant Klebsiella caused pneumonia (MDR-KPN). METHODS: From August 2008 to May 2010, 47 strains of MDR-KPN were collected from 6 hospitals in Hangzhou and Huzhou in Zhejiang province in China. Drug target genes to quinolones (gyrA, parC) and quinolone-resistance genes mediated by mobile genetic elements [qnrA, qnrB, qnrS, aac (6')-Ib-cr, qepA] were analyzed by PCR and verified by DNA sequencing. RESULTS: Positive results were found in 47 strains of MDR-KPN, 43 strains (91.5%) of gyrA mutation, 40 strains (85.1%) of parC mutation, 3 strains (6.4%) of qnrB2, 1 strain (2.1%) of qnrB 4, 8 strains (17.0%) of qnrS 1, 5 strains (10.6%) of qnrS 4, 2 strains (4.3%) of aac (6')-Ib-cr respectively. Moreover, 5 novel variants of gyrA (GenBank accession number: JN811952, JN811953, JN811954, JN811955, JN811956), 5 novel variants of parC (GenBank accession number: JN817432, JN817433, JN817434, JN817435, JN817436) were also identified. In addition, qnrS4 (GenBank accession number: JN836269) appeared to be the novel variants of qnrS. CONCLUSION: Quinolone-resistance-determining region played a key role on the resistance to quinolones in this group of MDR-KPN, and quinolone-resistance genes mediated by mobile genetic elements [qnrB2, qnrB4, qnrS1, qnrS4, aac (6')-Ib-cr] showed positive in some parts of the strains. This was the first report on emergence of qnrS4 in the world.