Genomic analysis of qnr-harbouring IncX plasmids and their transferability within different hosts under induced stress

Improvement of the conjugation transfer of N. gerenzanensis based on the synergistic effect of quorum sensing and antibiotic interference

Nonomuraea gerenzanensis (N. gerenzanensis) is known for its ability to biosynthesize A40926, the precursor of the glycopeptide antibiotic (GPA) Dalbavancin. However, challenges and uncertainties related to the genetic manipulation of the rare actinomycetes remain. In order to improve the conjugation transfer of N. gerenzanensis, the crucial factors affecting conjugal transfer were evaluated, including agar medium, mycelial state, donor-recipient ratio, magnesium ion concentration, and antibiotic coverage time firstly. Additionally, γ-butyrolactone (GBL) for quorum sensing (QS) and antibiotics targeting bacterial walls were applied to evaluate their effects on conjugation transfer. As a result, the optimal conditions of 5%TSB of liquid medium, 24 h of the period time, V0.1 of agar medium, 30 mM of magnesium ion, the ratio 10:1 of donor-to-recipient, and 27 h of the overlaying time of antibiotic were determined. Furthermore, the results showed that autoinducer GBL and GPA teicoplanin had a synergetic effect on the conjugation transfer of N. gerenzanensis at a working concentration of 60 µM and 0.5 µg mL-1, respectively. The highest conjugation efficiency could reach about 1.3 depending on the optimal process conditions and the interference of QS and antibiotics.

H. Shyu D, Chen YY, Zala D. Whole Genome Sequencing and Pan-Genomic Analysis of Multidrug-Resistant Vibrio cholerae VC01 Isolated from a Clinical Sample

Cholera, a disease caused by the Vibrio cholerae bacteria, threatens public health worldwide. The organism mentioned above has a significant historical record of being identified as a prominent aquatic environmental pollutant capable of adapting its phenotypic and genotypic traits to react to host patients effectively. This study aims to elucidate the heterogeneity of the sporadic clinical strain of V. cholerae VC01 among patients residing in Silvasa. The study involved conducting whole-genome sequencing of the isolate obtained from patients exhibiting symptoms, including those not commonly observed in clinical practice. The strain was initially identified through a combination of biochemical analysis, microscopy, and 16s rRNA-based identification, followed by type strain-based identification. The investigation demonstrated the existence of various genetic alterations and resistance profiles against multiple drugs, particularly chloramphenicol (catB9), florfenicol (floR), oxytetracycline (tet(34)), sulfonamide (sul2), and Trimethoprim (dfrA1). The pan-genomic analysis indicated that 1099 distinct clusters were detected within the genome sequences of recent isolates worldwide. The present study helps to establish a correlation between the mutation and the coexistence of antimicrobial resistance toward current treatment.

Quinolone Resistance Genes and Their Contribution to Resistance in Vibrio cholerae Serogroup O139

BACKGROUND

Quinolones are commonly used for reducing the duration of diarrhea, infection severity, and limiting further transmission of disease related to Vibrio cholerae, but V. cholerae susceptibility to quinolone decreases over time. In addition to mutations in the quinolone-resistance determining regions (QRDRs), the presence of qnr and other acquired genes also contributes to quinolone resistance.

RESULTS

We determined the prevalence of quinolone resistance related genes among V. cholerae O139 strains isolated in China. We determined that eight strains carried qnrVC, which encodes a pentapeptide repeat protein of the Qnr subfamily, the members of which protect topoisomerases from quinolone action. Four qnrVC alleles were detected: qnrVC1, qnrVC5, qnrVC12, and qnrVC9. However, the strains carrying qnrVC1, qnrVC5, and qnrVC12 were ciprofloxacin (CIP)-sensitive. Contrastingly, the strain carrying qnrVC9 demonstrated high CIP resistance. qnrVC9 was carried by a small plasmid, which was conjugative and contributed to the high CIP resistance to the receptor V. cholerae strain. The same plasmid was also detected in V. vulnificus. The qnrVC1, qnrVC5, and qnrVC12 were cloned into expression plasmids and conferred CIP resistance on the host V. cholerae O139 strain.

CONCLUSIONS

Our results revealed the contribution of quinolone resistance mediated by the qnrVC9 carried on the small plasmid and its active horizontal transfer among Vibrio species. The results also suggested the different effects of qnrVC alleles in different V. cholerae strains, which is possibly due to differences in sequences of qnrVC alleles and even the genetic characteristics of the host strains.

Klebsiella pneumoniae ST147: and then there were three carbapenemases

Gram-negative bacteria containing three different carbapenemases are extremely rare. Klebsiella pneumoniae (N22-925) with KPC-2, NDM-1, and OXA-48 was obtained from a Canadian patient with recent hospitalization in Romania. Short and long read whole genome sequencing showed that the bla_KPC-2 was situated on a 214 kb IncFIB(K)/IncFII(K) plasmid, the bla_NDM-1 on a 104 kb IncFIB (pQil)/IncFII(K) plasmid, and the bla_OXA-48 on a 64 kb IncL plasmid. These plasmids were conjugated to Escherichia coli J53. N22-925 belonged to a unique ST147 cluster that is likely endemic in Romania. This case emphasizes the need for rapid carbapenemase screening in patients from endemic regions. We described the first complete genome sequence of a K. pneumoniae isolate with three different carbapenemases, providing a reference for future studies on this rarely reported occurrence.