Explore the vast range of titles available.

can cause intestinal and extra-intestinal infections which ranged from mild to life-threatening infections. The severity of infection is a product of many factors including virulence properties and antimicrobial resistance. To determine the antibiotic resistance pattern, the distribution of virulence factors and their association with one another and with some selected resistance genes. Virulence properties were analyzed phenotypically while antimicrobial susceptibility was tested by Kirby-Bauer agar disc diffusion method. In addition, 64 isolates were tested for 6 colicin genes, virulence genes and , and resistance genes by polymerase chain reaction (PCR). Extra-intestinal pathogenic isolated from urine and blood samples represented a battery of virulence factors and resistance genes with a great ability to produce biofilm. Also, a significant association (P<0.05) among most of the tested colicin, virulence and resistance genes was observed. The observed associations indicate the importance and contribution of the tested factors in the establishment and the progress of infection especially with (ExPEC) which is considered a great challenging health problem. There is a need for studying how to control these factors to decrease the rate and the severity of infections. The relationship between virulence factors and resistance genes is complex and needs more studies that should be specific for each area.

To investigate the phenotypic and genomic characteristics of the multi-drug resistant and hypervirulent strain recovered from bacteremia. Antimicrobial susceptibility testing (AST) was performed by the microdilution method. Antimicrobial resistance genes, virulence-associated genes, multilocus sequence typing (MLST), and plasmid replicon were characterized by next-generation sequencing (NGS) and nanopore sequencing. S1 nuclease-pulsed field gel electrophoresis (S1-PFGE) and Southern blotting were performed to characterize the plasmid profile. The hypervirulent colistin- and carbapenem-resistant strain DY2009 was identified as ST5571, co-carrying , and . In silico analysis found that it was K2 serotype. AST results revealed that DY2009 was resistant to carbapenems, cephalosporins, ciprofloxacin, chloramphenicol, and colistin but remained susceptible to aztreonam, gentamicin, amikacin, and tigecycline. Through the whole-genome analysis, a variety of virulence determinants were identified, including . Plasmid analysis confirmed that the and gene harbored a ~33 kb IncX4 plasmid and a ~44 kb IncX3 plasmid. In contrast, was encoded by chromosome. To the best of our knowledge, we first report the clinical hypervirulent isolate co-producing MCR-1, NDM-1, and OXA-10 causing bacteremia. We found that and genes were located on two self-conjugative epidemic plasmids, contributing to the widespread MCR-1 and NDM-1 in China. The results of this work improve our understanding of the genetic background of colistin- and carbapenem-resistant isolate from bacteremia and the resistance mechanisms. Our findings highlight the urgent need for infection control of such strain to prevent it from becoming an extensive-drug resistant clone.

Background Providencia rettgeri is a nosocomial pathogen associated with urinary tract infections and related to Healthcare-Associated Infection (HAI). In recent years isolates producing New Delhi Metallo-β-lactamase (NDM) and other β-lactamases have been reported that reduce the efficiency of clinical antimicrobial treatments. In this study, we analyzed antibiotic resistance, the presence of resistance genes and the clonal relationship of two P. rettgeri isolates obtained from male patients admitted to the same hospital in Bogotá – Colombia, 2015. Results Antibiotic susceptibility profile evaluated by the Kirby-Bauer method revealed that both isolates were resistant to third-generation carbapenems and cephalosporins. Whole-genome sequencing (Illumina HiSeq) followed by SPAdes assembling, Prokka annotation in combination with an in-house Python program and resistance gene detection by ResFinder identified the same six β-lactamase genes in both isolates: bla NDM-1 , bla VIM-2 , bla CTX-M-15 , bla OXA-10 , bla CMY-2 and bla TEM-1 . Additionally, various resistance genes associated with antibiotic target alteration ( arn A, Pmr E, Pmr F, Lpx A, Lpx C, gyr B, fol P, mur A, rpo B, rps L, tet 34) were found and four efflux pumps ( Ros AB, Emr D, mdt H and cml A). The additional resistance to gentamicin in one of the two isolates could be explained by a detected SNP in CpxA (Cys191Arg) which is involved in the stress response of the bacterial envelope. Genome BLAST comparison using CGView, the ANI value (99.99%) and the pangenome (using Roary) phylogenetic tree (same clade, small distance) showed high similarity between the isolates. The rMLST analysis indicated that both isolates were typed as rST-61,696, same as the RB151 isolate previously isolated in Bucaramanga, Colombia, 2013, and the FDAARGOS_330 isolate isolated in the USA, 2015. Conclusions We report the coexistence of the carbapenemase genes bla NDM-1 , and bla VIM-2 , together with the β-lactamase genes bla CTX-M-15 , bla OXA-10 , bla CMY-2 and bla TEM-1 , in P. rettgeri isolates from two patients in Colombia. Whole-genome sequence analysis indicated a circulation of P. rettgeri rST-61,696 strains in America that needs to be investigated further.

The extensive use of β-lactam antibiotics has led to significant resistance, primarily due to hydrolysis by β-lactamases. OXA class D β-lactamases can hydrolyze a wide range of β-lactam antibiotics, rendering many treatments ineffective. We investigated the effects of single amino acid substitutions in OXA-10 on its substrate spectrum. Broad-spectrum variants with point mutations were searched and biochemically verified. Three key residues, G157D, A124T, and N73S, were confirmed in the variants, and their crystal structures were determined. Based on an enzyme kinetics study, the hydrolytic activity against broad-spectrum cephalosporins, particularly ceftazidime, was significantly enhanced by the G157D mutation in loop 2. The A124T or N73S mutation close to loop 2 also resulted in higher ceftazidime activity. All structures of variants with point mutations in loop 2 or nearby exhibited increased loop 2 flexibility, which facilitated the binding of ceftazidime. These results highlight the effect of a single amino acid substitution in OXA-10 on broad-spectrum drug resistance. Structure-activity relationship studies will help us understand the drug resistance spectrum of β-lactamases, enhance the effectiveness of existing β-lactam antibiotics, and develop new drugs.

The OXA-10 class D β-lactamase has been reported to contribute to carbapenem resistance in non-fermenting Gram-negative bacilli; however, its contribution to carbapenem resistance in Enterobacterales is unknown. In this work, minimum inhibitory concentrations (MICs), whole genome sequencing (WGS), cloning experiments, kinetic assays, molecular modelling studies, and biochemical assays for carbapenemase detection were performed to determine the impact of OXA-10 production on carbapenem resistance in two XDR clinical isolates of Escherichia coli with the carbapenem resistance phenotype (ertapenem resistance). WGS identified the two clinical isolates as belonging to ST57 in close genomic proximity to each other. Additionally, the presence of the blaOXA-10 gene was identified in both isolates, as well as relevant mutations in the genes coding for the OmpC and OmpF porins. Cloning of blaOXA-10 in an E. coli HB4 (OmpC and OmpF-deficient) demonstrated the important contribution of OXA-10 to increased carbapenem MICs when associated with porin deficiency. Kinetic analysis showed that OXA-10 has low carbapenem-hydrolysing activity, but molecular models revealed interactions of this β-lactamase with the carbapenems. OXA-10 was not detected with biochemical tests used in clinical laboratories. In conclusion, the β-lactamase OXA-10 limits the activity of carbapenems in Enterobacterales when combined with low permeability and should be monitored in the future.

In this study, we describe, for the first time, the co-existence of and in a carbapenem-resistant strain DY2019 isolated from a patient with urinary tract infection in China. We aimed to investigate the genomic context of two β-lactamase-producing plasmids and characterize the transmission mechanism of the carbapenemase-encoding gene. Whole-genome sequencing of strain DY2019 was performed with Nanopore and Illumina platforms, which revealed a chromosome sequence with the length of 4,830,928 bp, an IncC group plasmid pDY2019-OXA (size of 178,134 bp), and a novel IncHI2 group plasmid pDY2019-NDM (length 348,495 bp). A total of 16 antimicrobial resistance genes (ARGs) that confer resistance to nine different antibiotic groups were identified in strain DY2019, and 11 of them were carried by plasmid pDY2019-OXA. These data and analyses suggest that the carbapenem-resistant strains may serve as potential reservoir of carbapenemase and highlight the need for further close surveillance of this species in clinical settings.

Pseudomonas aeruginosa remains a leading cause of severe wound infection and mortality in burn patients. The current study aimed to determine the prevalence of Ambler class A and D β-lactamases among P. aeruginosa isolated from infected burn injuries in Tehran, Iran. Bacteriological samples were taken from burn patients with clinical symptoms of burn infection. Fifty Gram-negative, oxidase-positive, catalase- positive bacilli, grown at 42ºC and production of pigment on Mueller-Hinton agar were identified as P. aeruginosa. All of the 50 isolates were examined for antibiotic susceptibility via disk diffusion method, and production of Ambler class A and and D β-lactamases by phenotypic screening test. The presence of Ambler class A and D β-lactamases was confirmed by polymerase chain reaction technique. The results showed that the majority of isolates (88%) were multi-drug resistant. Out of these 50 imipenem resistant isolates, 7 (14%), 18 (36%), 18 (36%) and 18 (36%) strains were positive for bla PER , bla OXA-10 , bla TEM and bla SHV genes alone or in combination, respectively. None of the isolates possessed bla KPC or bla GES genes. The current study highlights that the high level of resistance to many antibacterial agents and a gradual increase in the degree of PER, OXA-10, SHV and TEM ESBLs among the majority of imipenem resistant P. aeruginosa isolated from patients with burn infection is an enormous threat in burn centers in Iran.

The current study reports dissemination of highly stable bla family of beta lactamases among diverse group of nosocomial isolates of Gram-negative bacilli within a tertiary referral hospital of the northern part of India. In the current study, a total number of 590 Gram negative isolates were selected for a period of 1 year (i.e. 1st November 2011-31st October 2012). Members of Enterobacteriaceae and non fermenting Gram negative rods were obtained from Silchar Medical College and Hospital, Silchar, India. Screening and molecular characterization of β-lactamase genes was done. Integrase gene PCR was performed for detection and characterization of integrons and cassette PCR was performed for study of the variable regions of integron gene cassettes carrying bla . Gene transferability, stability and replicon typing was also carried out. Isolates were typed by ERIC as well as REP PCR. Twenty-four isolates of Gram-negative bacilli that were harboring bla family (OXA-14, and OXA16) with fact that resistance was to the extended cephalosporins. The resistance determinant was located within class I integron in five diverse genetic contexts and horizontally transferable in Enterobacteriaceae, was carried through IncY type plasmid. MIC values were above break point for all the tested cephalosporins. Furthermore, co-carriage of bla was also observed. Multiple genetic environment of bla in this geographical region must be investigated to prevent dissemination of these gene cassettes within bacterial population within hospital settings.

Background: Klebsiella is one of the Enterobacteriaceae family that causes infections such as pneumonia, urinary tract infections (UTI), and meningitis. Klebsiella strains are capable of producing enzymes that can degrade the third-generation of cephalosporins known as broad-spectrum beta-lactamase enzymes. The resistance of Klebsiella strains to β-lactam antibiotics is related to the presence of β-lactamase genes.Methods: In this study, 90 isolates of Klebsiella were isolated from two inpatient and outpatient groups, each of them was 45 isolates, which were collected from patients with urinary tract infection in educational hospitals of Shahrekord. The isolates were identified using phenotypic agar diffusion, disc phenotypic confirmation tests, and E-test of extended-spectrum beta-lactamase (ESBL). The PCR molecular method was used to diagnose and determine the strains containing broad-spectrum β-lactamases.Results: Thirty (66%) inpatients and 8 (17.8%) outpatients had broad-spectrum β-lactamase enzymes. The frequency of β-lactamase OXA-10 genes and PER in inpatients were 90% and 33%, respectively and also in outpatients were 50% and 12.5%, respectively.Conclusions: This study showed that the prevalence of isolated Klebsiella producing broad-spectrum β-lactamases is higher in inpatients in comparison to outpatients. Therefore, the rapid and accurate identification of bacteria and their resistance genes in clinical microbiology labs are highly recommended.

We investigated the extended-spectrum (ESBLs) and metallo-beta-lactamases (MBLs) among Pseudomonas aeruginosa isolates in Saudi Arabia. Disc susceptibility testing was performed on 200 P. aeruginosa isolates collected during 2010 at the Armed Forces Hospital in Riyadh, with MIC testing and phenotypic screening for ESBLs and MBLs carried out on those found to be ceftazidime resistant. Genes for ESBLs and MBLs were sought by PCR. Thirty-nine (19·5%) P. aeruginosa isolates were ceftazidime resistant, mostly with considerable resistance to other antibiotics except colistin. Twenty-three of these 39 (59%) appeared ESBL positive and 16 (41%) had MBLs. blaVEB, and blaGES genes were found in 20 (86·95%), and 5 (21·74%) of 23 ESBL-positive isolates, respectively whilst blaVIM was detected in all 16 MBL-producers. blaOXA-10-like often accompanied blaVEB, blaVIM or blaGES. Several isolates had similar antibiogram and β-lactamase profiles, and may represent outbreaks; nevertheless, the collection was not dominated by any single clone. This dominance of acquired ceftazidime-inactivating beta-lactamases, often in combination is in contrast to the situation in Europe and the USA, where most ceftazidime resistance in P. aeruginosa is attributable to AmpC and efflux. [PUBLICATION ABSTRACT]