Search Results (5)

Background: The increase in antimicrobial resistance includes emerging mechanisms such as 16S ribosomal RNA methylases, which confer high-level resistance to aminoglycosides. In this regard, the most predominant genes observed worldwide are rmtB and armA, but their presence in Uruguay is unknown. Objectives: We describe the genomic characterization of isolates carrying rmtB and rmtC, together with bla_NDM-5 and bla_NDM-1, respectively, and rmtD in our country. Methology: Five isolates from patients admitted to three hospitals were studied. Identification and antibiotic susceptibility testing were performed using the Vitek2 System. Whole Genome Sequencing was conducted, and hybrid assembly was performed with Unicycler. In silico analysis using the Center for Genomic Epidemiology’s tools was undertaken to predict antibiotic resistance determinants, plasmid incompatibility groups, and sequence types. Results: We report three K. pneumoniae ST307 isolates with an IncR plasmid carrying bla_NDM-5/bla_CTX-M-15/bla_TEM-1B/rmtB/dfrA14/dfrA12/sul1/qacEΔ1/ermB/mphA, one K. pneumoniae ST258 harboring an IncC plasmid containing rmtC/bla_NDM-1/bla_CMY-6/aac(6′)-Ib/sul1, and one E. cloacae ST88 isolate with an IncFIB/II plasmid hosting rmtD, within a novel Tn21-like transposon named Tn7825, alongside bla_OXA-101/sul1/tet(G)/floR, and a new variant of bla_TEM assigned as bla_TEM-258. One of the strains, named UH_B2, also carried an IncM1 plasmid encoding qnrE1/bla_TEM-1/bla_CTX-M-8 associated with ISEcp1. Conclusions: This is the first description of plasmids harboring 16S rRNA methyltransferases in Uruguay. The association and dissemination of diverse antibiotic-resistant genes underpin the health threat they represent, highlighting the lack of available antibiotics effective against multidrug-resistant microorganisms. Full article

The rapid spread of carbapenemase-producing strains has led to increased levels of resistance among Gram-negative bacteria, especially enterobacteria. The current study aimed to collect and genetically characterize the colistin- and carbapenem-resistant isolates, obtained in one of the biggest hospitals (Military Medical Academy) in Sofia, Bulgaria. Clonal relatedness was detected by RAPD and MLST. Carbapenemases, ESBLs, and mgrB were investigated by PCR amplification and sequencing, replicon typing, and 16S rRNA methyltransferases with PCRs. Fourteen colistin- and carbapenem-resistant K. pneumoniae isolates were detected over five months. Six carbapenem-resistant and colistin-susceptible isolates were also included. The current work revealed a complete change in the spectrum of carbapenemases in Bulgaria. bla_NDM-5 was the only NDM variant, and it was always combined with bla_OXA-232. The coexistence of bla_OXA-232 and bla_NDM-5 was observed in 10/14 (72%) of colistin- and carbapenem-resistant K. pneumoniae isolates and three colistin-susceptible isolates. All bla_NDM-5- and bla_OXA-232-positive isolates belonged to the ST6260 (ST101-like) MLST type. They showed great mgrB variability and had a higher mortality rate. In addition, we observed bla_OXA-232 ST14 isolates and KPC-2-producing ST101, ST16, and ST258 isolates. The colistin- and carbapenem-resistant isolates were susceptible only to cefiderocol for bla_NDM-5- and bla_OXA-232-positive isolates and to cefiderocol and ceftazidime/avibactam for bla_OXA-232- or bla_KPC-2-positive isolates. All bla_OXA-232-positive isolates carried rmtB methylase and the colE replicon type. The extremely limited choice of appropriate treatment for patients infected with such isolates and their faster distribution highlight the need for urgent measures to control this situation. Full article

Carbapenem-resistant Pseudomonas aeruginosa (P. aeruginosa) strains have become a global threat due to their remarkable capability to survive and disseminate successfully by the acquisition of resistance genes. As a result, the treatment strategies have been severely compromised. Due to the insufficient available data regarding P. aeruginosa resistance from Pakistan, we aimed to investigate the resistance mechanisms of 249 P. aeruginosa strains by antimicrobial susceptibility testing, polymerase chain reaction for the detection of carbapenemases, aminoglycoside resistance genes, extended-spectrum beta-lactamases (ESBLs), sequence typing and plasmid typing. Furthermore, we tested silver nanoparticles (AgNPs) to evaluate their in vitro sensitivity against antimicrobial-resistant P. aeruginosa strains. We observed higher resistance against antimicrobials in the general surgery ward, general medicine ward and wound samples. Phenotypic carbapenemase-producer strains comprised 80.7% (201/249) with 89.0% (179/201) demonstrating genes encoding carbapenemases: bla_NDM-1 (32.96%), bla_OXA48 (37.43%), bla_IMP (7.26%), bla_VIM (5.03%), bla_KPC-2 (1.12%), bla_NDM-1/bla_OXA48 (13.97%), bla_OXA-48/bla_VIM (1.68%) and bla_VIM/bla_IMP (0.56%). Aminoglycoside-modifying enzyme genes and 16S rRNA methylase variants were detected in 43.8% (109/249) strains: aac(6′)-lb (12.8%), aac(3)-lla (12.0%), rmtB (21.1%), rmtC (11.0%), armA (12.8%), rmtD (4.6%), rmtF (6.4%), rmtB/aac(3)-lla (8.2%), rmtB/aac(6′)-lla (7.3%) and rmtB/armA (3.6%). In total, 43.0% (77/179) of the strains coharbored carbapenemases and aminoglycoside resistance genes with 83.1% resistant to at least 1 agent in 3 or more classes and 16.9% resistant to every class of antimicrobials tested. Thirteen sequence types (STs) were identified: ST235, ST277, ST234, ST170, ST381, ST175, ST1455, ST1963, ST313, ST207, ST664, ST357 and ST348. Plasmid replicon types IncFI, IncFII, IncA/C, IncL/M, IncN, IncX, IncR and IncFIIK and MOB types F11, F12, H121, P131 and P3 were detected. Meropenem/AgNPs and Amikacin/AgNPs showed enhanced antibacterial activity. We reported the coexistence of carbapenemases and aminoglycoside resistance genes among carbapenem-resistant P. aeruginosa with diverse clonal lineages from Pakistan. Furthermore, we highlighted AgNP’s potential role in handling future antimicrobial resistance concerns. Full article

Hospital-acquired infections caused by P. aeruginosa contribute to global distress because of the elevated rates of microbial antibiotic resistance. Aminoglycosides are antipseudomonal agents that are effectively and frequently utilized to eradicate this infection. This current study is a retrospective study investigating plasmid-mediated aminoglycoside resistance by focusing on the prevalence of the genes encoding aminoglycoside-modifying enzymes (AMEs) and 16S rRNA methylase among P. aeruginosa clinical isolates from Taif, Saudi Arabia. A hundred clinical isolates of P. aeruginosa were collected. The isolates were identified from February 2021 to February 2022. Antibiotic susceptibility testing and MICs were determined using (DD) and (BM-MIC) testing, respectively. AMEs and 16S rRNA methylase variants in bacterial isolates were amplified via PCR for genetic detection. A relatively high multiple antibiotic resistance rate corresponding to 10–32% was reported. Eighteen percent of P. aeruginosa isolates were gentamicin–amikacin–tobramycin resistant according to the MIC levels. The aminoglycoside-resistant strains were additionally identified via GyrA gene sequencing. The phylogenic relatedness dendrogram of the sequenced GyrA genes was performed using a neighbor-joining method via MEGAX software version 10.2.6. The most prevalent AME encoding gene was aac(6′)-Ib, observed in 94.4% of resistant isolates, while a resistance gene cocktail of [aac(6′)-Ib and ant(3″)-I] was a highly frequent combination (27.8%). This study updated the knowledge about aminoglycoside resistance mechanisms in P. aeruginosa, which constitutes an urgent need, especially after the COVID-19 crisis, which was associated with increased antimicrobial use and resistance rates. Full article

The widespread use of antibiotics in large-scale livestock production has led to serious antibiotic resistance. Proteus mirabilis is an important pathogenic bacterium on large-scale farms. Chromosomally localized mobilizable genetic elements (genomic islands) and mobile genetic elements (Tn7-like transposons) play an important role in the acquisition and transmission of resistance genes by P. mirabilis. To study the prevalence and resistance characteristics of antibiotic-resistant genomic islands in P. mirabilis of animal origin in China, we performed whole genome sequencing of P. mirabilis isolated from large-scale pig and chicken farms. Three new variants of PmGRI1 (HN31, YN8, and YN9), and a hybrid structure (HN2p) formed by the multidrug-resistant Tn7-like-HN2p transposon and a genomic island PmGRI1-HN2p, were identified from P. mirabilis. All variants underwent homologous recombination mediated by insertion sequence IS26. A genomic rearrangement in the chromosome between the Tn7-like-HN2p transposon and PmGRI1-HN2p occurred in HN2p. The heterozygous structure contained various antimicrobial resistance genes, including three copies of fluoroquinolone resistance gene qnrA1 and 16S rRNA methylase gene rmtB, which are rarely found in P. mirabilis. Our results highlight the structural genetic diversity of genomic islands by characterizing the novel variants of PmGRI1 and enrich the research base of multidrug resistance genomic islands. Full article