OXA Genes Research Articles

Antimicrobial Profiling of Resistant Genes in Bacteria Isolated from Drinking Water Sources in Bonny Island, Rivers State, Nigeria

The global health crisis of antimicrobial resistance (AMR) necessitates a profound understanding of its dynamics, particularly in environmental reservoirs such as drinking water sources. The aim of the study was to identify the presence and variety of antibiotic-resistant genes (ARGs) within bacteria isolated from drinking water sources in Bonny Island, Rivers State, Nigeria – an area characterized by unique ecological and human-induced factors. Eighty water samples were collected from drinking water distribution systems within Bonny Island for a period of six month. Bacteria isolated from drinking water samples within Bonny Island underwent antimicrobial profiling, including susceptibility tests against a range of clinically relevant antibiotics. Molecular techniques were employed to identify the isolated bacteria and characterize specific ARGs, illuminating the genetic basis of resistance in the isolated bacteria. The bacterial isolates displayed varying resistance patterns, with the highest resistance observed against cefuroxime (59.6%), cefotaxime (48.9%), ceftazidime (44.7%), ceftriaxone (36.3%), chloramphenicol, and Augmentin (29.8%), while resistance to cotrimoxazole and gentamicin was lower (12.8%). Among the bacterial isolates, the tet gene, conferring resistance to tetracycline antibiotics, was present in 46.7% of cases, while 100% exhibited the oxa gene and 93.3% possessed the aac(6’)-ib gene. Preliminary findings revealed a diverse array of bacteria with varying resistance profiles, including both common and emerging pathogens. The identified ARGs covered genes providing resistance to a broad spectrum of antibiotics, including beta-lactams, fluoroquinolones, and tetracyclines. These results underscore the potential risks associated with the spread of ARGs in drinking water sources and their potential transfer to pathogenic bacteria.

Study Gene Expression of OXA-48and CTX-M-1 Genes Cephalosporin resistance in Escherichia coli isolated from urinary tract infections in Baghdad hospitals

Escherichia coli are a normal flora in the human. It is pathogenic in patients with immune system disorders and is the leading cause of enteritis, urinary tract infection, septicemia and other medical infections. E. coli is the most common cause of community and hospital-acquired urinary tract infections (UTIs). It is responsible for >80% of all cases of UTI. These study samples were taken from Al-Karama Teaching Hospital and Al-Yarmouk Teaching Hospital in Baghdad. This study aimed to determine the Minimum Inhibition concentration (MIC) of Ceftazidim. As well as comparing the effect of antibiotics and without antibiotics on beta-lactam genes (OXA-48 –CTXM-1) resistance to Cephalosporin where there is an overexpression of gene expression in the antibiotic between (125-64) µg/ml. Bacteria produce beta-lactam enzymes that break down the beta-lactam ring in the antibiotic, which reduces the effectiveness of antibiotics. This mechanism is one of the mechanisms of resistance in bacteria. The presence of both genes increases the resistance of this species to Cephalosporin. The results of gene expression when treated with antibiotics for the OXA-48 gene in his sample were 1.4, and the highest value was 14.5, as well as for the CTX-M-1 gene, where the results ranged between the lowest value of 1.3 and the highest value of 7.3 when compared to the control samples, we notice an overexpression of gene. It was concluded that the resistance of E. coli to Ceftazidim was related to the genes blaOXA45 and CTXM-1, but the primary role may be due to blaOXA45. Keywords: Gene Expression, OXA-48 Gene, CTX-M-1 Gene, Cephalosporin, Escherichia coli.

Designing a Multiplex PCR for Rapid and Accurate Detection of Metallobetalactamases Resistant Genes from Acinetobacter baumaniiIsolates in Tehran City, Iran.

Acinetobacter baumannii strains harboring Meallobetalactamases (MBL) pose a significant threat in the context of nosocomial infections. The present investigation was undertaken with the objective of devising a Multiplex PCR methodology for the concurrent detection of MBL genes within A. baumannii strains prevalent in Tehran City, Iran. Between October 2020 and February 2021, 100 strains of A. baumannii were procured from burn specimens of hospitalized patients at Motahhari Hospital in Tehran. The identification of A. baumannii strains involved conventional biochemical techniques, coupled with confirmation of the presence of the bla OXA-51 gene. Antibiotic susceptibility was assessed using the Kirby-Bauer disc diffusion test. MBL-producing strains were characterized through a phenotypic approach employing the combined disk test, alongside Multiplex PCR for the simultaneous identification of bla VIM, bla IMP, bla GIM, and bla NDM genes. Statistical analyses were conducted using the chi-square test, with SPSS version 20.0 employed for data processing. Among 100 strains examined, 96.1% exhibited positivity for MBL, as determined by the combined disk test. The study revealed a predominance of extensively drug-resistant (XDR) strains, with colistin demonstrating the highest level of sensitivity. The genotypic assay unveiled that Multiplex PCR identified bla VIM, bla NDM, and bla IMP in 20 strains, bla VIM and bla NDM in 30 strains, and exclusively the bla NDM gene in 45 strains. Notably, the Multiplex PCR technique exhibited the capacity to concurrently detect MBL genes (bla VIM, bla IMP, bla GIM, bla NDM) in 2 strains. The current investigation underscores prevalence of the bla NDM gene within clinical strains of A. baumannii. Furthermore, Multiplex PCR emerges as a robust and highly sensitive technique for rapid discernment of the MBL genes within in A. baumannii strains.

B-066 Evaluation on Effectiveness of Colloidal Gold Immunochromatography Assay for Rapid Detection of Carbapenemase-producing Enterobacteriaceae

Abstract Background The identification, treatment, and control of carbapenem-resistant Enterobacteriaceae (CRE) infections are a major challenge for health care institutions and diagnostic laboratories worldwide. A novel Carbapenemase-producing Bacteria Test Kit (Lateral Flow Assay) from Dynamiker Biotechnology (Tianjin) Co., Ltd. is a qualitative test that was easy to operate and can be widely accepted by clinical and primary medical. Results can be read in just 15 minutes using colloidal gold immunochromatography, which can detect double and multiple carbapenemase types (Fig. 1). We analyzed the effectiveness of Dynamiker carbapenemase-producing bacteria test kit for rapid detection of CRE carbapenemase. Methods A total of 120 strains of Enterobacterales in blood culture were collected, including 80 strains of CRE and 40 strains of CSE (carbapenem-susceptibility Enterobacteriaceae). PCR was used to detect KPC, NDM, IMP, VIM and OXA-48 genes as gold standard. Dynamiker carbapenemase-producing bacteria test kit was used to detect the carbapenemase produced by CRE, which was conducted by the performance evaluation combined with PCR results. Results The 80 strains of CRE expressing carbapenemase genes were all positive for the detection of carbapenemasstre by Dynamiker carbapenemase-producing bacteria test kit, which includes 39 strains producing KPC, 26 strains producing NDM, 8 strains producing IMP, 5 strains producing VIM and 2 strains producing OXA-48 enzymes; the 40 strains of CSE were negative and no carbapenemase were detected. Compared with the PCR results, the sensitivity and specificity of the four enzymes by Dynamiker carbapenemase-producing bacteria test kit were both 100% (Fig. 2). Conclusion Dynamiker carbapenemase-producing bacteria test kit can be applied as a simple, rapid, sensitive and specific diagnostic method for the detection of different CRE carbapenemase types, which is of great value for the accurate use of clinical anti-infective therapy.Fig. 1.Operating procedures of colloidal gold immunochromatography.Fig. 2.Results of Dynamiker carbapenemase-producing bacteria test kit C: Control, K: KPC, N: NMD, I: IMP, V: VIM, O: OXA-48.

Analysis of Osmotic Tolerance, Physiological Characteristics, and Gene Expression of Salmonella enterica subsp. enterica Serotype Derby.

Salmonella is an important foodborne pathogen, and recent epidemiological studies have shown high infection rates of Salmonella enterica subsp. enterica serotype Derby (S.Derby) in poultry in western China and other regions. S.Derby presents increasing concerns with the development of resistance to hypertonic environments; however, there are few reports investigating the mechanism of resistance. Therefore, in this study, we examined hypertonic adaptation in S.Derby at the physiological and molecular levels. The K-B paper method, wiping glass bead method, crystal violet staining, and RT-PCR combined with comparative genomics analysis were employed to characterize virulence, drug resistance, biofilm formation, and changes in gene expression of genes related to hypertonic adaptation in S.Derby. Hypertonic-adapted S.Derby exhibited resistance to OXA, AMP, PEN, and CEP antibiotics, and biofilm-forming ability was 1.25 times that of nonadapted S.Derby. RT-PCR results showed that compared with nonadapted S.Derby, the expression of virulence-related genes in hypertonic-adapted S.Derby increased by 2-3 times, that of biofilm-related genes increased by 2-4 times, and that of OXA, AMP, PEN, and CEP-related drug resistance genes was relatively high. Four hypertonic tolerance-related genes (otsA, proV, proW, omsV) were preliminarily identified in S.Derby. The expression of proW was always relatively high in hypertonic-adapted S.Derby, the expression of otsA gradually became higher than that of proW with increasing time of osmotic stress, and the expression of proV and omsV was only high in non-hypertonic-adapted S.Derby.

Dissemination of the Acinetobacter baumannii isolates belonging to global clone 2 containing AbGRI resistance islands in a referral hospital.

Acinetobacter baumannii strains belonging to global clone 2 (GC2) contain resistance islands (AbGRIs), which are composed of genes conferring resistance to older and newer antibiotics. Here, to locate these genes in AbGRIs, the GC2 strains from Tehran, Iran were examined. Among the 170 A. baumannii, 90 isolates were identified as GC2. Of the genes that confer resistance to older antibiotics, tetA(B), tetR(B) (tetracyclines), strA, and strB (aminoglycosides) were located in AbGRI1 of 65 GC2 isolates (72.2%). Of the other aminoglycosides, the aphA1b was located in AbGRI2-12b (63.6%), AbGRI2-12a (21.2%), or AbGRI2-1 (15.1%). The aacC1 and aadA1 genes were co-located within AbGRI2-1 (5.5%). The armA was located in AbGRI3-4 (77.7%) and AbGRI3ABI221 (22.2%). Of sulfonamides, the sul1 was located within AbGRI2-1 (5.5%). Of beta-lactams, the blaTEM was located in AbGRI2-12b (42%), AbGRI2-12a (14%), AbGRI2-1 (10%), or AbGRI2ABI257 (34%). The oxa23 gene conferring resistance to newer antibiotics (carbapenems) was located in AbaR4 (81.1%); of them, the AbaR4 was located within AbGRI1 in 45.2% of the isolates. This study showed that the GC2 isolates, which contained at least one AbGRI, disseminate in the hospital. Hence, it is likely that the AbGRIs play a significant role in conferring resistance to older and newer antibiotics in GC2 isolates from Iran. IMPORTANCE The majority of Acinetobacter baumannii isolates that are resistant to multiple antibiotics belong to one of the two major global clones, namely global clone 1 (GC1) and global clone 2 (GC2). The resistance islands, which contain variable assortments of transposons, integrons, and specific resistance genes, have been characterized in the genome of these GCs. In GC2 A. baumannii, the chromosomally located A. baumannii genomic resistance islands (AbGRIs) carry the genes conferring resistance to older and newer antibiotics. In this context, we tested whether GC2 isolates collected from a referral hospital carry the AbGRIs containing these genes. This study provided evidence for the circulation of the GC2 A. baumannii strains harboring AbGRI resistance islands between different wards of a referral hospital.

Molecular characterization of Carbapenem-resistant Escherichia coli isolates from sewage at Mulago National Referral Hospital, Kampala: a cross-sectional study

BackgroundEscherichia coli (E. coli) is one of the most frequent causes of fatal bacterial infections affecting both humans and animals. The resistance to Carbapenems is mainly associated with enzyme-mediated resistance mechanism, through the acquisition of Carbapenemase genes. In Uganda, no studies have been done to detect presence of Carbapenem-resistant E. coli in sewage. We therefore carried out a study to characterize Carbapenem-resistant E. coli from sewage from Mulago National Referral Hospital.Methods and resultsIn this cross-sectional study, a total of 104, sewage samples were aseptically collected, cultured on MacConkey agar supplemented with Meropenem 1 µg/ml with other standard microbiology methods to screen for Carbapenem-resistant E. coli (CREC). Antimicrobial susceptibility testing was performed on the CREC, using Imipenem (10 mg/disc) and Meropenem (10 mg/disc), Carbapenem drugs readily available on market. Multiplex PCR was performed on selected Carbapenem-resistant and susceptible isolates to detect Carbapenemase genes. Later the isolates were pathotyped for virulence genes that included pathogenicity islands (PAIs) and phylogenetic markers. The results showed that the Carbapenem-resistant E. coli isolates were more resistant to Meropenem (64%) than Imipenem (60%). KPC gene was the most predominant (75%), followed by NDM gene (30%) while no OXA-48, IMP-1, and IMP-2 genes were detected. Pathotyping of virulence genes showed presence of eae gene, as the most predominant (40%), followed by elt gene (25%) and negative for stx and aggR genes. For PAI markers, only the PAI IV536 gene was detected at 10%. Then, pathotyping of the phylogenetic markers was present in 85% of the typed isolates with yjaA gene the most abundant (60%) while both chuA and TSPE4.C2 were detected in 5% of the isolates.ConclusionBoth pathogenic and non-pathogenic Carbapenem-resistant E. coli strains are present in the sewage of Mulago National Referral Hospital in Uganda.

Endogenous Bacteremia Caused by Intestinal Colonization of Carbapenem-Resistant Enterobacteriaceae (CRE) in Immunocompromised Children.

Carbapenem-resistant Enterobacteriaceae (CRE) infection is life-threatening, especially for immunocompromised children. The source tracking of CRE could prevent bacteremia during hospitalization. In this study, the intestinal colonization of CRE and their translocation to blood were investigated. Stool samples from immunocompromised pediatric patients were collected after admission, and secondary stool and blood samples were collected in case of fever. After CRE phonotypic detection, the OXA-48, NDM-1, VIM, IMP, and KPC genes were detected by PCR. Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) was used to determine the phylogenic relatedness of the blood and fecal isolates. Bacteremia was recorded in 71.4% of the patients. Enterobacteriaceae spp. were recorded in 100% of the stool samples and 31% of the blood samples. The correlation between the length of stay (LOS), days of fever, chemotherapy regimens, and death rate was significant (p-value ≤ 0.05). OXA-48 was present in all CRE isolates in both the primary and the secondary stool samples and the blood samples. According to the phylogenetic data, 58.33% of the patients with bacteremia had identical blood and stool isolates. The death rate was 24.4% in children with CRE bacteremia. The primary intestinal colonization with CRE in immunocompromised pediatrics and their translocation to blood was established in this study. The implementation of infection control programs and the application of infection prevention strategies for immunocompromised children is necessary.

Frequency of OXA-Type Carbapenemases among Carbapenem-Resistant Acinetobacter baumannii in Clinical Isolates from Adult Intensive Care Unit in India

Abstract Purpose Acinetobacter baumannii is a highly virulent bacteria in modern health care, with a high ability to acquire antimicrobial resistance. Carbapenemases production appears to be the most common mechanism involved in drug resistance to carbapenem. As the prevalence of carbapenem-resistant A. baumannii was high in intensive care unit (ICU) patients, this study was designed to find the frequency of oxacillinases (OXA) genes including OXA-23, OXA-24, OXA-51, and OXA-58. Materials and Methods A clinical specimen was collected from patients admitted to the adult ICU. DNA was isolated from carbapenem-resistant A. baumannii and amplified using conventional polymerase chain reaction technique and gel electrophoresis for visualization of results. Results The frequency of the OXA-23 gene was high with 87.5%, followed by OXA-51 gene with 73.2%. All 56 isolates were negative for the OXA-24 and OXA-58 genes. We also found that both OXA-23 and OXA-51 genes coexisted in 40 (71.4%) isolates. No significant difference was found between drug-resistant genes (OXA-23 and OXA-51) and clinical outcomes. The relationship between the presence of OXA gene was compared between survivors and nonsurvivors, which was found out to be nonsignificant. The presence of OXA genes showed no significant increase in the length of hospital stay. The significant association between acute physiology and chronic health evaluation IV scores and clinical outcome was calculated, and it was evident in the comparison of the discharged and died groups. Conclusion Early detection of these drug-resistant genes by molecular methods is essential in decreasing the spread of carbapenem-resistant A. baumannii.

Prevalence of OXA genes responsible for carbapenem-resistance among Acinetobacter baumannii isolated from clinical samples in Iraq

Abstract Background: Acinetobacter, measured as an opportunistic pathogen has lately occurred as a vital nosocomial pathogen in the world, frequently relating patients with reduced host defenses. Patients in dangerous cases obtain infections while they are staying in care wards, so the incidence of these infections varies significantly in different individuals and clinical settings. Objectives: This work aims to examine the prevalence of carbapenem-resistance genes among isolates of Acinetobacter baumannii gathered from three hospitals in Iraq. Materials and Methods: A total of 30 isolates of A. baumannii were gathered from different clinical samples from February to July 2022. DNA of all specimens was extracted. Gradient polymerase chain reaction was applied to discover the genes of bla-OXA carbapenemases. Results: The results exhibited a variation of carbapenemase genes in all isolates that had been examined. Although all isolates had at least three genes of carbapenemase that have been tested, the most commonly identified genes in class D β-lactamases were bla OXA-51 and bla OXA-23 which was established in all isolates of A. baumannii 30 (100%) tested. It was also found that nine (30%) of tested isolates had borne the gene of bla OXA-58. No isolate exhibited amplification for the gene of bla OXA-40. Conclusion: The maximum occurrence and prevalence of the genes of OXA β-lactamase in A. baumannii bacteria in Iraqi hospitals were bla OXA-23 and bla OXA-51.

Metabolomics revealed mechanism for the synergistic effect of sulbactam, polymyxin-B and amikacin combination against Acinetobacter baumannii.

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii prompts clinicians to consider treating these infections with polymyxin combination. Metabolomic analysis was applied to investigate the synergistic effects of polymyxin-B, amikacin and sulbactam combination therapy against MDR A. baumannii harboring OXA-23 and other drug resistant genes. The drug concentrations tested were based on their clinical breakpoints: polymyxin-B (2 mg/L), amikacin (16 mg/L), polymyxin-B/amikacin (2/16 mg/L), and polymyxin-B/amikacin/sulbactam (2/16/4 mg/L). The triple antibiotic combination significantly disrupted levels of metabolites involved in cell outer membrane structure including fatty acids, glycerophospholipids, nucleotides, amino acids and peptides as early as 15 min after administration. Amikacin and polymyxin-B alone perturbed a large number of metabolites at 15 min and 1 h, respectively, but the changes in metabolites were short-lived lasting for less than 4 h. In contrast, the combination treatment disrupted a large amount of metabolites beyond 4 h. Compared to the double-combination, the addition of sulbactam to polymyxin-B/amikacin combination produce a greater disorder in A. baumannii metabolome that further confer susceptibility of bacteria to the antibiotics. The metabolomic analysis identified mechanisms responsible for the synergistic activities of polymyxin-B/amikacin/sulbactam against MDR A. baumannii.

Phenotypic and Genotypic Detection of Carbapenem Resistant Organism Causing Nosocomial Infection in Patients Attending Tertiary Care Hospital

Aims: Nosocomial infections are the leading cause of mortality. ESKAPE organisms are the primary causes of nosocomial infection as these organisms are more or less carbapenem resistant. This study aimed to isolate and identify the etiological agents responsible for causing nosocomial infection and determine the carbapenemase producing organism by phenotypic and genotypic detection.
 Study Design: The study design is cross-sectional study.
 Place and Duration of Study: The study was conducted in the Department of Microbiology, at Index Medical College, Indore, between January 2020 and January 2022.
 Methodology: Total of 246 samples was collected from the patients who develop symptoms after 48- 72 hrs of hospitalization. Samples were processed for identification of etiological agents. Gram negative organisms were selected and further identified for carbapenemase enzyme. Screening was done by Kirby Bauer disc diffusion test and further confirmed by Modified Hodge test, Combined Disc test, Double Disc Synergy Diffusion test and Carbapenem Inactivation method. Genotypic detection was done by using multiplex polymerase chain reaction for KPC, NDM and OXA-48 gene.
 Results: Out of 107-gram-negative organisms, 19 (17.75%) were carbapenem resistant. Among 19 carbapenem resistant GNR, 13% MHT, 15% CCDT, 17% DDST and 17% mCIM were positive. The sensitivity and specificity of MHT, CCDT, DDST, mCIM were 74%/100, 84%/100,95%/100 and 95%/100respectively. The genotypic detection shows highest percentage of blaNDM 74% which is followed by bla OXA-48 31% and blaKPC 26%.
 Conclusion: Hospitals have become the hotspot for various microorganism causing nosocomial infections and are getting carbapenem resistance due to irrational use of antibiotics. Antimicrobial stewardship is one of the effective measures that minimize the resistance. Proper universal precaution can also minimize, spread of resistance in organism. If the last resort drug gets resistant, then it could be challenging for the clinician to treat their patients. Hospitals should have regular HAI meeting and release of antibiogram to know the pattern of these notorious organisms invading infection.

GENOTYPIC RESISTANCE DRUGS OF ESCHERICHIA COLI STRAINS ISOLATED FROM KAZAKHSTANI PRODUCERS’ CHEESES TO ANTIMICROBIAL

Global spread of antimicrobial resistance among pathogens is alarming for the modern society. The research aimed to study distribution of Escherichia coli in cheeses produced in Kazakhstan and to assess its resistance to antibacterial drugs. There were collected 101 samples of cheeses at retail outlets in different regions of Kazakhstan in 2021-2023, from which 55(54.4%) E. coli strains were isolated using conventional microbiological methods. The strains were phenotypically evaluated for antibiotic resistance, and the resistant isolates were tested for antibiotic resistance genes for the β-lactams group-penicillins (blaTEM, blaSHV, and OXA genes), aminoglycosides (aphA1, aadB), tetracyclines (tetA, tetB), quinolones (qnrA, qepA) and sulphonamides (sul1, sul2, and sul3 genes). Among studied E. coli strains 61% were resistant to at least one of the 21 antibiotics tested and were multi-resistant to the 15 antibacterial drugs. The greatest resistance was to sulfamethoxazole (43.6%), tetracycline (32%), followed by cefoxitin (29%). Isolates showed resistance to gentamicin (18.1%), ofloxacin (12.7%), furadonin (11%), amoxicillin (9.1%), doxycycline (7.2%). A gene encoding resistance to sulfonamides (sul3) was identified in eight E. coli strains. Thus, genotypic antibiotic resistance has been established in E. coli populations contaminating cheeses produced in the central, northern and eastern regions of Kazakhstan.

Induced Expression of the Acinetobacter sp. Oxa Gene in Lactobacillus acidophilus and Its Increased ZEN Degradation Stability by Immobilization.

Zearalenone (ZEN, ZEA) contamination in various foods and feeds is a significant global problem. Similar to deoxynivalenol (DON) and other mycotoxins, ZEN in feed mainly enters the body of animals through absorption in the small intestine, resulting in estrogen-like toxicity. In this study, the gene encoding Oxa, a ZEN-degrading enzyme isolated from Acinetobacter SM04, was cloned into Lactobacillus acidophilus ATCC4356, a parthenogenic anaerobic gut probiotic, and the 38 kDa sized Oxa protein was expressed to detoxify ZEN intestinally. The transformed strain L. acidophilus pMG-Oxa acquired the capacity to degrade ZEN, with a degradation rate of 42.95% at 12 h (initial amount: 20 μg/mL). The probiotic properties of L. acidophilus pMG-Oxa (e.g., acid tolerance, bile salt tolerance, and adhesion properties) were not affected by the insertion and intracellular expression of Oxa. Considering the low amount of Oxa expressed by L. acidophilus pMG-Oxa and the damage to enzyme activity by digestive juices, Oxa was immobilized with 3.5% sodium alginate, 3.0% chitosan, and 0.2 M CaCl2 to improve the ZEN degradation efficiency (from 42.95% to 48.65%) and protect it from digestive juices. The activity of immobilized Oxa was 32-41% higher than that of the free crude enzyme at different temperatures (20-80 °C), pH values (2.0-12.0), storage conditions (4 °C and 25 °C), and gastrointestinal simulated digestion conditions. Accordingly, immobilized Oxa could be resistant to adverse environmental conditions. Owing to the colonization, efficient degradation performance, and probiotic functionality of L. acidophilus, it is an ideal host for detoxifying residual ZEN in vivo, demonstrating great potential for application in the feed industry.

In-vitro activity of oral third-generation cephalosporins plus clavulanate against ESBL-producing Enterobacterales isolates from the MERINO trial

Extended-spectrum-beta-lactamase (ESBL)-producing Enterobacterales as a cause of community-acquired uncomplicated urinary tract infection (UTI) is on the rise. Currently, there are minimal oral treatment options. New combinations of existing oral third-generation cephalosporins paired with clavulanate may overcome resistance mechanisms seen in these emerging uropathogens. Ceftriaxone-resistant Escherichia coli and Klebsiella pneumoniae containing CTX-M-type ESBLs or AmpC, in addition to narrow-spectrum OXA and SHV enzymes, were selected from blood culture isolates obtained from the MERINO trial. Minimum inhibitory concentration (MIC) values of third-generation cephalosporins (cefpodoxime, ceftibuten, cefixime, cefdinir), both with and without clavulanate, were determined. One hundred and one isolates were used with ESBL, AmpC and narrow-spectrum OXA genes (e.g. OXA-1, OXA-10) present in 84, 15 and 35 isolates, respectively. Susceptibility to oral third-generation cephalosporins alone was very poor. Addition of 2 mg/L clavulanate reduced the MIC50 values (cefpodoxime MIC50 2 mg/L, ceftibuten MIC50 2 mg/L, cefixime MIC50 2 mg/L, cefdinir MIC50 4 mg/L) and restored susceptibility (33%, 49%, 40% and 21% susceptible, respectively) in a substantial number of isolates. This finding was less pronounced in isolates co-harbouring AmpC. In-vitro activity of these new combinations may be limited in real-world Enterobacterales isolates co-harbouring multiple antimicrobial resistance genes. Pharmacokinetic/pharmacodynamic data would be useful for further evaluation of their activity.

Detection of Β-Lactamase OXA Genes and Biofilm Production in Carbapenem Resistant Gram-Negative Bacilli

Objectives: The emergence of carbapenem resistance in biofilm producer Gram-negative bacteria poses a substantial challenge to manage infections. This study aimed to evaluate biofilm production and molecular characterization of carbapenem resistance Gram-negative rods. Methods: Total of 46 bacteria were isolated from various clinical samples, including blood, CSF, urine, sputum, saliva, tracheal secretion, and pus. Following the standard guidelines for bacterial identification (CLSI), bacterial pathogens are isolated and identified. The antibiotic susceptibility profile was obtained against commercially available antibiotics including Amoxicillin, Amikacin, Ceftazidime, Cefepime, Imipenem, Meropenem, Gentamycin, Tobramycin, Doxycycline, Minocycline, Tazobactam, Ciprofloxacin, and Levofloxacin following CLSI guidelines. Biofilm production potential was quantified by using 96-well flat bottom microtiter plates. Phenotypic and molecular characterization of carbapenem-resistant bacteria was performed. The genotypic resistance to carbapenem was determined using OXA-23, OXA-24, OXA-51 and OXA-58 gene primers. Results: The Gram-negative bacterial strains were found as Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens. The phenotypic resistance against carbapenem drugs was 95%. DNA of carbapenem-resistant bacteria isolated by commercially available kit and polymerase chain reaction assay was performed and optimized to identify OXA-23 (84%), OXA-24(90%), OXA-51(83%) and OXA-58(80%) gene in bacterial strains. Practical Implication: For better and prompt management of antimicrobial resistance further work on genetics is required and warranted to produce gene effective drugs to enhance antimicrobial effect of carbapenems. Conclusion: The prevalence of carbapenem resistance among Gram-negative bacilli was high. OXA genes have raised clinical concern and further study is required to detect carbapenemase-producing bacteria. Keywords: Antibiotic Resistance, Biofilm, Carbapenem-resistance, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, β-lactamases, OXA-23, OXA-24, OXA-51 and OXA-58

Characterization and Antibiotic Susceptibility Testing Of Acinetobacter Species in a Tertiary Care Hospital with Special Reference to NDM and OXA Genes

Characterization and Antibiotic Susceptibility Testing Of Acinetobacter Species in a Tertiary Care Hospital with Special Reference to NDM and OXA Genes

A Correlation between 3'-UTR of OXA1 Gene and Yeast Mitochondrial Translation.

Mitochondria possess their own DNA (mtDNA) and are capable of carrying out their transcription and translation. Although protein synthesis can take place in mitochondria, the majority of the proteins in mitochondria have nuclear origin. 3' and 5' untranslated regions of mRNAs (3'-UTR and 5'-UTR, respectively) are thought to play key roles in directing and regulating the activity of mitochondria mRNAs. Here we investigate the association between the presence of 3'-UTR from OXA1 gene on a prokaryotic reporter mRNA and mitochondrial translation in yeast. OXA1 is a nuclear gene that codes for mitochondrial inner membrane insertion protein and its 3'-UTR is shown to direct its mRNA toward mitochondria. It is not clear, however, if this mRNA may also be translated by mitochondria. In the current study, using a β-galactosidase reporter gene, we provide genetic evidence for a correlation between the presence of 3'-UTR of OXA1 on an mRNA and mitochondrial translation in yeast.

The emergence of plasmid-encoded oxacillinase and carbapenemase among uropathogenic Escherichia coli (UPEC) isolated from hospitalized patients in the North of Iran

Carbapenemase enzyme production is responsible for resistance to carbapenem among Gram-negative bacteria. This study aimed to detect common carbapenemase and oxacilinase genes among uropathogenic E. coli (UPEC) isolated from hospitalized patients in Rasht, north of Iran. In the present study, from 2000 urine samples, 263 UPEC strains were isolated from inpatients with urinary tract infections (UTI) in 2020. The Kirby-Bauer disk diffusion susceptibility test was used to determine the sensitivity or resistance of isolates to antimicrobial compounds. The double-disk test confirmed extended-spectrum β lactamase (ESBL) production phenotypically, and the presence and distribution of genes encoding carbapenemase and oxacilinase were investigated using polymerase chain reaction (PCR). Based on the findings, 13/263 isolates (8 ESBL and five non-ESBL) showed a non-susceptible phenotype to at least one of the studied carbapenem group antibiotics, and 121 (46%) isolates were ESBL-producers. PCR for oxacilinase and carbapenemase genes was done on all 126 isolates, including ESBL-positive and carbapenem-resistant strains, in which 10 (7.9%) and 25 (19.8%) isolates harbored OXA-1 and IMP genes, respectively. Also, OXA-2, OXA-10, OXA-48, VIM, and NDM genes were not found in any studied isolates. IMP and OXA-1 genes among carbapenemase-producing isolates indicate the possible spread of antibiotic-resistant strains. Hence, identification and control of ESBL and carbapenemase-producing strains, although with almost low frequency due to plasmid genes encoding carbapenemase, is essential for infection control.

High prevalence of extensively drug resistant and extended spectrum beta lactamases (ESBLs) producing uropathogenic Escherichia coli isolated from Faisalabad, Pakistan.

Urinary tract infections (UTIs) are predominantly caused by uropathogenic Escherichia coli (E. coli). There is rapid increase in antimicrobial resistance in UTIs, also declared as a serious health threat by World Health Organization (WHO). Present study was designed to investigate the antimicrobial resistance status with specific focus on ESBLs and carbapenemases in local uropathogenic E. coli (UPEC) isolates. E. coli isolates were characterized from patients of all ages visiting diagnostic laboratories for urine examination. Demographic data was also recorded for each patient. Antibiograms were developed to observe antibiotic resistance in UPEC using Kirby Bauer disc diffusion technique. Double Disc Synergy test (DDST) was used for phenotypic ESBL test. ESBLs and carbapenemases genes were detected in UPEC using PCR. The PCR results were confirmed by sequencing. The UPEC isolates under study exhibited 78%, 77%, 74%, 72% and 55% resistance against cefotaxime, amoxicillin, erythromycin, ceftriaxone and cefixime, respectively. Resistance against colistin and meropenem was observed in 64% and 34% isolates, respectively. Phenotypic DDST identified 48% isolates as ESBLs producers. Genotypic characterization identified 70%, 74.4% and 49% prevalence of CTXM-1, TEM-1 and CTXM-15 genes respectively. One isolate was observed exhibiting co-existence of all ESBL genes. TEM-1 + CTXM-1 and TEM-1 + CTXM-1 + CTXM-15 + OXA-1 gene patterns were dominant among ESBLs. For carbapenem-resistance, 14% isolates indicated the presence of KPC whereas GES and VIM was detected in 7% and 3.4% isolates, respectively. In conclusion, our results present a high prevalence of extensively drug resistant UPEC isolates with a considerable percentage of ESBL producers. These findings propose the need of continuous surveillance for antimicrobial resistance and targeted antimicrobial therapy.