bioRxiv Science⌕ Search

Biology subjects

Bakthavatchalam, Y. D.

Publications and source records attributed to Bakthavatchalam, Y. D..

2 recordsLinked to original sources

ompC/F mutations drive XDR phenotype and lineage defining super clones of E. coli: Sequential events and consequences

Multi-drug resistant Escherichia coli is an increasing public health problem. Though, PBP3 insertions with blaNDM, blaCMY and blaOXA-48 like is restricted to South-East Asia with few reports from USA. The study suggests ompC/F variants as a core factor to classify ESBL (E), non-ESBL (NE), and ESBL with PBP3 and carbapenemases (EPBP3) clones. EPBP3 results in treatment complication, as most of the time, E. coli with PBP3 insertions co-carries blaNDM (87.5%), blaCMY (96.3%) and blaOXA-48 like (88.8%) implicating it as a predisposing factor for carbapenemase gene acquirement. Cefiderocol and cefepime/zidebactam are the choice against EPBP3 E. coli. Evolutionary BEAST analysis revealed consecutive events of YRIN and YRIK insertions in PBP3 gene leading to a surge in MDR E. coli clones. Further, emergence of the super clones STs 410, 405, 167 and 617 featuring these phenotypes is a major threat for developing and developed countries, which needs close monitoring. ImportanceThe manuscript describes various E. coli resistant genotypes across the globe and their importance in the choice of antimicrobial for treatment. The study identified six clades based on ompC and ompF mutations with a strong correlation to PBP3 insertions co-carried with beta-lactamases including blaNDM. Though, the ompC and ompF mutations were reported to precede the acquisition of carbapenemases in E. coli, clade segregation based on AMR genes as observed in this study reveals the ompC and ompF genes as a potential biomarker for AMR clade identification in E. coli. Currently, cefiderocol and cefepime/zidebactam seems to be the only choice to cover the AMR mechanism mediated by PBP3 insertions. Further, emergence of the super clones STs 410, 405, 167 and 617 featuring these PBP3 phenotypes is a major threat for developing and developed countries, which needs close monitoring.

genomics↗

Origin and evolutionary dynamics of multi-drug resistant and highly virulent community-associated methicillin-resistant Staphylococcus aureus ST772-SCCmec V lineage

BackgroundCommunity-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are increasing in prevalence across the world. However, studies on the molecular epidemiology and the genomic investigation of MRSA are limited in India. ObjectivesTo understand the molecular epidemiology of MRSA and to reconstruct the origin and evolution of S. aureus belonged to the sequence type (ST772). MethodsA total of 233 non-repetitive MRSA isolates were screened for the presence staphylococcal cassette chromosome (SCCmec) types, multi-locus sequence types (MLST) and staphylococcal protein A (spa) types. Whole genome sequence data of ST772-SCCmec V (n=32) isolates were generated and analysed along with the publically available ST772-SCCmec V (n=273) genome. ResultsST772 (27%), ST22 (19%) and ST239 (16%) were found as the predominant STs. Analysis of the core SNPs using Bayesian time scaled phylogenetic analysis showed ST772-SCCmec V was emerged on the Indian subcontinent in 1960s. The acquisition of integrated resistance plasmid (IRP) in the ST772-SCCmec V lineage during 1990s, fixation of SCCmec V (5C2) and the double serine mutations (S84L, S80Y) appears to have played a key role in the successful expansion. The IRP carries the loci for multiple antibiotic resistant genes: beta-lactam (blaZ), aminoglycosides (aphA3-sat-aadE), macrolide (mphC), macrolide-lincosamide-streptogramin B (msrA) and bacitracin (bacA, bacB). ConclusionThe Panton Valentine Leukocidin (PVL) positive ST772 and ST22 MRSA lineages are observed in the hospital settings. ST772-SCCmec V has the multi-drug resistance trait of hospital-associated (HA) MRSA and the epidemiological characteristics of CA-MRSA. The antimicrobial use pattern may have driven the spread and survival of ST772 MRSA in hospitals.

microbiology↗