blaOXA Genes Research Articles

Dynamic state of plasmid genomic architectures resulting from XerC/D-mediated site-specific recombination in Acinetobacter baumannii Rep_3 superfamily resistance plasmids carrying blaOXA-58 - and TnaphA6-resistance modules.

The acquisition of bla OXA genes encoding different carbapenem-hydrolyzing class-D β-lactamases (CHDL) represents a main determinant of carbapenem resistance in the nosocomial pathogen Acinetobacter baumannii. The blaOXA-58 gene, in particular, is generally embedded in similar resistance modules (RM) carried by plasmids unique to the Acinetobacter genus lacking self-transferability. The ample variations in the immediate genomic contexts in which blaOXA-58 -containing RMs are inserted among these plasmids, and the almost invariable presence at their borders of non-identical 28-bp sequences potentially recognized by the host XerC and XerD tyrosine recombinases (pXerC/D-like sites), suggested an involvement of these sites in the lateral mobilization of the gene structures they encircle. However, whether and how these pXerC/D sites participate in this process is only beginning to be understood. Here, we used a series of experimental approaches to analyze the contribution of pXerC/D-mediated site-specific recombination to the generation of structural diversity between resistance plasmids carrying pXerC/D-bounded bla OXA-58- and TnaphA6-containing RM harbored by two phylogenetically- and epidemiologically-closely related A. baumannii strains of our collection, Ab242 and Ab825, during adaptation to the hospital environment. Our analysis disclosed the existence of different bona fide pairs of recombinationally-active pXerC/D sites in these plasmids, some mediating reversible intramolecular inversions and others reversible plasmid fusions/resolutions. All of the identified recombinationally-active pairs shared identical GGTGTA sequences at the cr spacer separating the XerC- and XerD-binding regions. The fusion of two Ab825 plasmids mediated by a pair of recombinationally-active pXerC/D sites displaying sequence differences at the cr spacer could be inferred on the basis of sequence comparison analysis, but no evidence of reversibility could be obtained in this case. The reversible plasmid genome rearrangements mediated by recombinationally-active pairs of pXerC/D sites reported here probably represents an ancient mechanism of generating structural diversity in the Acinetobacter plasmid pool. This recursive process could facilitate a rapid adaptation of an eventual bacterial host to changing environments, and has certainly contributed to the evolution of Acinetobacter plasmids and the capture and dissemination of bla OXA-58 genes among Acinetobacter and non-Acinetobacter populations co-residing in the hospital niche.

Virulence potential of multidrug-resistant Acinetobacter baumannii isolates from COVID-19 patients on mechanical ventilation: The first report from Serbia.

Since the WHO declared the COVID-19 pandemic in March 2020, the disease has spread rapidly leading to overload of the health system and many of the patients infected with SARS-CoV-2 needed to be admitted to the intensive care unit (ICU). Around 10% of patients with the severe manifestation of COVID-19 need noninvasive or invasive mechanical ventilation, which represent a risk factor for Acinetobacter baumannii superinfection. The 64 A. baumannii isolates were recovered from COVID-19 patients admitted to ICU at General Hospital "Dr Laza K. Lazarević" Šabac, Serbia, during the period from December 2020 to February 2021. All patients required mechanical ventilation and mortality rate was 100%. The goal of this study was to evaluate antibiotic resistance profiles and virulence potential of A. baumannii isolates recovered from patients with severe form of COVID-19 who had a need for mechanical ventilation. All tested A. baumannii isolates (n = 64) were sensitive to colistin, while resistant to meropenem, imipenem, gentamicin, tobramycin, and levofloxacin according to the broth microdilution method and MDR phenotype was confirmed. In all tested isolates, representatives of international clone 2 (IC2) classified by multiplex PCR for clonal lineage identification, bla AmpC, bla OXA-51, and bla OXA-23 genes were present, as well as ISAba1 insertion sequence upstream of bla OXA-23. Clonal distribution of one dominant strain was found, but individual strains showed phenotypic differences in the level of antibiotic resistance, biofilm formation, and binding to mucin and motility. According to PFGE, four isolates were sequenced and antibiotic resistance genes as well as virulence factors genes were analyzed in these genomes. The results of this study represent the first report on virulence potential of MDR A. baumannii from hospital in Serbia.

Rapid culture-independent loop-mediated isothermal amplification detection of antimicrobial resistance markers from environmental water samples.

Environmental water is considered one of the main vehicles for the transmission of antimicrobial resistance (AMR), posing an increasing threat to humans and animals health. Continuous efforts are being made to eliminate AMR; however, the detection of AMR pathogens from water samples often requires at least one culture step, which is time-consuming and can limit sensitivity. In this study, we employed comparative genomics to identify the prevalence of AMR genes within among: Escherichia coli, Klebsiella, Salmonella enterica and Acinetobacter, using publicly available genomes. The mcr-1, blaKPC (KPC-1 to KPC-4 alleles), blaOXA-48, blaOXA-23 and blaVIM (VIM-1 and VIM-2 alleles) genes are of great medical and veterinary significance, thus were selected as targets for the development of isothermal loop-mediated amplification (LAMP) detection assays. We also developed a rapid and sensitive sample preparation method for an integrated culture-independent LAMP-based detection from water samples. The developed assays successfully detected the five AMR gene markers from pond water within 1h and were 100% sensitive and specific with a detection limit of 0.0625 μg/mL and 10cfu/mL for genomic DNA and spiked bacterial cells, respectively. The integrated detection can be easily implemented in resource-limited areas to enhance One Health AMR surveillances and improve diagnostics.

OprL Gene Sequencing, Resistance Patterns, Virulence Genes, Quorum Sensing and Antibiotic Resistance Genes of XDR Pseudomonas aeruginosa Isolated from Broiler Chickens.

Pseudomonas aeruginosa is incriminated in septicemia, significant economic losses in the poultry production sector, and severe respiratory infections in humans. This study aimed to investigate the occurrence, oprL sequencing, antimicrobial resistance patterns, virulence-determinant, Quorum sensing, and antibiotic resistance genes of P. aeruginosa retrieved from broiler chickens. Two hundred samples were collected from 120 broiler chickens from broiler farms at Ismailia Governorate, Egypt. Consequently, the bacteriological examination was conducted and the obtained P. aeruginosa strains were tested for oprL gene sequencing, antibiogram, and PCR screening of virulence, Quorum sensing, and antibiotic resistance genes. The overall prevalence of P. aeruginosa in the examined birds was 28.3%. The oprL gene sequence analysis underlined that the tested strain expressed a notable genetic identity with various P. aeruginosa strains isolated from different geographical areas in the USA, India, China, Chile, and Ghana. PCR evidenced that the obtained P. aeruginosa strains, carrying virulence-related genes: oprL, toxA, aprA, phzM, and exoS in a prevalence of 100%, 100%, 42.5%, 33.3%, and 25.9%, respectively. Moreover, the recovered P. aeruginosa strains possessed the Quorum sensing genes: lasI, lasR, rhlI, and rhlR in a prevalence of 85.2%, 85.2%, 81.5%, and 81.5%, respectively. Furthermore, 40.7% of the isolated P. aeruginosa were XDR to seven antimicrobial classes, possessing sul1, bla TEM, tetA, bla CTX-M, bla OXA-1, and aadA1 genes. As we can tell,thisisthefirstreportemphasizing theevolutionofXDRP. aeruginosastrainsfrom broiler chicken in Egypt, which is supposed to be a serious threat to public health.The emerging XDR P. aeruginosa in poultry frequently harbored the oprL, toxA, and aprA virulence genes, the lasI, lasR, rhlI, and rhlR Quorum sensing genes, and the sul1, bla TEM, tetA, bla CTXM, bla OXA-1, and aadA1 resistance genes.

Resistance to critically important antibiotics in hospital wastewater from the largest Croatian city

The emergence of extended-spectrum β-lactamase (ESBL)- and especially carbapenemases in Enterobacterales has led to limited therapeutic options. Therefore, it is critical to fully understand all potential routes of transmission, especially in high-risk sources such as hospital wastewater. This study aimed to quantify four enteric opportunistic pathogens (EOPs), total, ESBL- and carbapenem-resistant coliforms and their corresponding resistance genes (two ESBL and five carbapenemase genes) and to characterize enterobacterial isolates from hospital wastewater from two large hospitals in Zagreb over two seasons. Culturing revealed similar average levels of total and carbapenem-resistant coliforms (3.4 × 104 CFU/mL), and 10-fold lower levels of presumptive ESBL coliforms (3 × 103 CFU/mL). Real-time PCR revealed the highest E. coli levels among EOPs (105 cell equivalents/mL) and the highest levels of the blaKPC gene (up to 10−1 gene copies/16S copies) among all resistance genes examined. Of the 69 ESBL- and 90 carbapenemase-producing Enterobacterales (CPE) isolates from hospital wastewater, all were multidrug-resistant and most were identified as Escherichia coli, Citrobacter, Enterobacter, and Klebsiella. Among ESBL isolates, blaCTX-M-15 was the most prevalent ESBL gene, whereas in CPE isolates, blaKPC-2 and blaNDM-1 were the most frequently detected CP genes, followed by blaOXA-48. Molecular epidemiology using PFGE, MLST and whole-genome sequencing (WGS) revealed that clinically relevant variants such as E. coli ST131 (blaCTX-M-15/blaTEM-116) and ST541 (blaKPC-2), K. pneumoniae ST101 (blaOXA-48/blaNDM-1), and Enterobacter cloacae complex ST277 (blaKPC-2/blaNDM-1) were among the most frequently detected clone types. WGS also revealed a diverse range of resistance genes and plasmids in these and other isolates, as well as transposons and insertion sequences in the flanking regions of the blaCTX-M, blaOXA-48, and blaKPC-2 genes, suggesting the potential for mobilization. We conclude that hospital wastewater is a potential secondary reservoir of clinically important pathogens and resistance genes and therefore requires effective pretreatment before discharge to the municipal sewer system.

Prevalence of carbapenemase genes blaOXA-51 and blaOXA23 in multi-drug resistance Acinetobacter baumannii isolated from hospital environment

Prevalence of carbapenemase genes blaOXA-51 and blaOXA23 in multi-drug resistance Acinetobacter baumannii isolated from hospital environment

First Report of OXA-48 and IMP Genes Among Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Isolates from Diarrheic Calves in Tunisia.

Antimicrobial resistance is one of the most serious threats to human and animal health. Evidence suggests that the overuse of antimicrobial agents in animal production has led to the emergence and dissemination of multidrug-resistant isolates. The objective of this study was to assess the rate of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in calf feces and to characterize their resistance genes for antibiotics like beta-lactams and colistin, but also to determine their virulence genes. Fecal samples were collected from 100 diarrheic calves in the region of Bizerte, Tunisia. After isolation, E. coli isolates were screened for antimicrobial resistance against 21 antibiotics by the disc diffusion method. Characterization of β-lactamase genes and determination of associated resistance genes were performed by polymerase chain reaction. Among 71 E. coli isolates, 26 (36.6%) strains were ESBL-producing. Most of these isolates were multidrug-resistant (92.3%) and the most prevalent beta-lactamase genes detected were blaCTX-M (n = 26), blaSHV (n = 11), and blaTEM (n = 8), whereas only 1 isolate carried the blaCMY gene. In addition, resistance to carbapenems was detected in two isolates; one of them harbored both blaOXA-48 and blaIMP genes and the other isolate carried only the blaIMP gene. Several resistance genes were identified for the first time in Tunisia from cases of diarrheic calves. Furthermore, to the best of our knowledge, this is the first report of detection and identification of carbapenem resistance genes and virulence genes from calves in North Africa. A high occurrence of antimicrobial resistance of E. coli recovered from fecal samples of calves with diarrhea was observed, highlighting the need for prudent use of antimicrobial agents in veterinary medicine to decrease the incidence of multidrug-resistant bacteria for both animals and humans.

Multidrug-Resistant ESBL-Producing E. coli in Clinical Samples from the UK.

Globally, cephalosporin therapy failure is a serious problem for infection control. One causative agent of cephalosporin-resistant infections is multidrug-resistant (MDR) E. coli producing extended-spectrum β-lactamases (ESBLs) and/or plasmid-encoded AmpC (pAmpC) β-lactamases. We evaluated the occurrence of ESBL/pAmpC genetic determinants in phenotypically MDR E. coli isolated from clinical samples of blood, faeces, ear effusion, urine and sputum from a UK hospital. Phenotypic resistance profiling for 18 antibiotics (from seven classes) showed that 32/35 isolates were MDR, with resistance to 4-16 of the tested antibiotics. Of the isolates, 97.1% showed resistance to ampicillin, 71.4% showed resistance to co-amoxiclav, cefotaxime, ceftazidime and ceftiofur, and 68.5% showed resistance to cefquinome. blaCTX-M, blaTEM and blaOXA-1 genes were detected in 23, 13 and 12 strains, respectively, and Intl1 was detected in 17 isolates. The most common subtypes among the definite sequence types were CTX-M-15 (40%) and TEM-1 (75%). No E. coli isolates carried pAmpC genes. Significant correlations were seen between CTX-M carriage and cefotaxime, ceftiofur, aztreonam, ceftazidime and cefquinome resistance; between blaCTX-M, blaTEM and blaOXA-1 carriage and ciprofloxacin resistance; and between Intl1 carriage and trimethoprim/sulfamethoxazole resistance. Thus, MDR phenotypes may be conferred by a relatively small number of genes. The level and pattern of antibiotic resistance highlight the need for better antibiotic therapy guidelines, including reduced use and improved surveillance.

Antibiotic-Resistant Bacteria, Antimicrobial Resistance Genes, and Antibiotic Residue in Food from Animal Sources: One Health Food Safety Concern.

Antibiotic-resistant bacteria causing foodborne serious illnesses can be found in contaminated food. Therefore, this study aimed to identify the pathogens, genes, and antimicrobial residues present in raw milk and meat. We collected 40 raw milk and 40 beef samples using the aseptic method from various parts of the Faisalabad metropolis, Pakistan. The samples were cultured on blood, MacConkey, and UTI chrome agar. The VITEK 2 compact system was used for microbial identification and determination of minimum inhibitory concentrations. Antimicrobial resistance genes for extended-spectrum β-lactamases, methicillin resistance in Staphylococcus aureus, and carbapenem resistance were identified using molecular techniques. ELISA was used to determine the tetracycline residue level in each sample. The beef samples showed polymicrobial contamination with 64 bacterial isolates, with Escherichia coli (29; 45.3%) and Klebsiella pneumoniae (11; 17.1%) predominating. The milk samples showed polymicrobial contamination with 73 bacterial isolates, with E. coli (22; 30%), K. pneumoniae (12; 16.4%), and S. aureus (10; 13.6%) forming the majority. Twenty-eight (43.7%) isolates from beef harbored tet genes, nineteen (29.6%) blaCTX-M, and fourteen (21.8%) blaNDM-1, and twenty-six (35.6%) isolates from milk harbored tet genes, nineteen (26%) blaTEM and blaCTX-M, and three (4%) blaNDM-1. Twenty-two (55%) each of the beef and milk samples exceeded the maximum residue limit for tetracycline. Polymicrobial contamination by bacteria possessing blaCTX-M, blaTEM, blaNDM-1, blaOXA, mecA, and tet genes was identified in food samples. The high tetracycline residue levels pose a serious health risk to consumers.

Susceptibility profile of bla OXA-23 and metallo-β-lactamases co-harbouring isolates of carbapenem resistant Acinetobacter baumannii (CRAB) against standard drugs and combinations.

The rapid emergence of carbapenem resistant Acinetobacter baumannii (CRAB) has resulted in an alarming situation worldwide. Realizing the dearth of literature on susceptibility of CRAB in genetic context in the developing region, this study was performed to determine the susceptibility profile against standard drugs/combinations and the association of in-vitro drug synergy with the prevalent molecular determinants. A total of 356 clinical isolates of A. baumannii were studied. Confirmation of the isolates was done by amplifying recA and ITS region genes. Susceptibility against standard drugs was tested by Kirby Bauer disc diffusion. Minimum inhibitory concentration (MIC), MIC50 and MIC90 values against imipenem, meropenem, doripenem, ampicillin/sulbactam, minocycline, amikacin, polymyxin B, colistin and tigecycline was tested as per guidelines. Genes encoding enzymes classes A (bla GES, bla IMI/NMC-A, bla SME, bla KPC), B (bla IMP, bla VIM, bla NDM) and D (bla OXA-51, bla OXA-23 and bla OXA-58) were detected by multiplex polymerase chain reaction. Synergy against meropenem-sulbactam and meropenem-colistin combinations was done by checkerboard MIC method. Correlation of drug synergy and carbapenemase encoding genes was statistically analyzed. Of the total, resistance above 90% was noted against gentamicin, ciprofloxacin, levofloxacin, ceftazidime, cefepime, ceftriaxone, cotrimoxazole and piperacillin/tazobactam. By MIC, resistance rates from highest to lowest was seen against imipenem 89.04% (n=317), amikacin 80.33% (n=286), meropenem 79.49% (n=283), doripenem 77.80% (n=277), ampicillin/sulbactam 71.62% (n=255), tigecycline 55.61% (n=198), minocycline 14.04% (n=50), polymyxin B 10.11% (n=36), and colistin 2.52% (n=9). CRAB was 317 (89.04%), 81.46% (n=290) were multidrug resistant and 13.48% (n=48) were extensively drug resistant. All the CRAB isolates harboured bla OXA-51 gene (100%) and 94% (n=298) bla OXA-23 gene. The bla IMP gene was most prevalent 70.03% (n=222) followed by bla NDM, 59.62% (n=189). Majority (87.69%, 278) were co-producers of classes D and B carbapenemases, bla OXA-23 with bla IMP and bla NDM being the commonest. Synergy with meropenem-sulbactam and meropenem-colistin was 47% and 57% respectively. Reduced synergy (p= <0.0001) was noted for those harbouring bla OXA-51+blaOXA-23with bla NDM gene alone or co-producers. Presence of bla NDM gene was a significant cause of synergy loss in meropenem-sulbactam and meropenem-colistin. In bla NDM endemic regions, tigecycline, minocycline and polymyxins could be viable options against CRAB isolates with more than one carbapenemase encoding genes.

Molecular Characteristics of an NDM-4 and OXA-181 Co-Producing K51-ST16 Carbapenem-Resistant Klebsiella pneumoniae: Study of Its Potential Dissemination Mediated by Conjugative Plasmids and Insertion Sequences.

The carbapenem-resistant Klebsiella pneumoniae (CRKP) strain GX34 was recovered from the respiratory tract of an elderly male with severe pneumonia, and only susceptible to amikacin, tigecycline, and colistin. Complete genome suggested that it belonged to K51-ST16 and harbored plasmid-encoded NDM-4 and OXA-181, located on IncFIB plasmid GX34p1_NDM-4 and ColKP3/IncX3 plasmid GX34p4_OXA-181, respectively. A series of transconjugants generated in the plasmid conjugation assays, including Escherichia coli J53-N1 (harboring a self-transmissible and blaNDM-1-producing plasmid Eco-N-1-p), J53-N2 (harboring a blaNDM-4-producing plasmid and a helper plasmid GX34p5), and J53-O (harboring a blaOXA-181-producing plasmid), could be stably inherited after 10 days of serial passage and no significant biological fitness costs were detected. Furthermore, we first reported the blaNDM-1 gene, derived from blaNDM-4 mutation (460C>A) under meropenem pressure, could be in vitro transferred into a self-conjugative, recombined plasmid Eco-N-1-p of J53-N1. Eco-N-1-p was mainly recombined by GX34p4_OXA-181 (40,449 bp, 75.16%) and GX34p1_NDM-4 (8,553 bp, 15.89%), in which IS26 and IS5-like probably played a major role. Eco-N-1-p could be transferred into the conjugation recipient K. pneumoniae KP54 and make the latter sacrifice fitness. The retention rates of blaNDM-1 remained high stability (>80% after 200 generations). The comparative genomic analysis of GX34 and those carrying blaNDM-4 or blaOXA-181 genes retrieved from the NCBI RefSeq database showed all blaNDM-4 (26/26, 100.00%) and blaOXA-181 (13/13, 100.00%) were surrounded by IS26. The immediate environment of blaNDM-4 and blaOXA-181 in GX34 and some retrieved strains shared identical features, hinting at their possible dissemination. Effective measures should be taken to monitor the spread of this clone.

Detection of Virulence Factors and Antibiotic Resistance among Klebsiella pneumoniae Isolates from Iran.

The current study assessed the detection of virulence genes and drug resistance among Klebsiella pneumoniae isolates from Iran. During 2018 to 2020, 52 K. pneumoniae isolates were obtained from patients at Iran hospitals. By disk diffusion method, the antimicrobial susceptibility of K. pneumoniae isolates was assessed, and ESBL-producing K. pneumoniae isolates were detected by CDDT method. PCR analysis was done to detect virulence genes (iucB, iutA, iroN, kfu, allS, fimH, ybtS, mrkD, and entB); ESBL-encoding genes (bla TEM, bla PER, bla CTX-M, bla VEB, and bla SHV); and class D (bla OXA-48), class B (bla VIM, bla NDM, and bla IMP), and class A (bla KPC and bla GES) carbapenemase genes. Among all isolates, 84.6%, 13.5%, and 1.9% isolates were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. Also, 84.6% were ESBL-producing and 71.2%, 53.8%, 40.4%, and 9.6% of all isolates were carrying bla TEM, bla SHV, bla CTX-M, and bla OXA-48 genes, respectively. Six isolates (11.5%) were positive for bla NDM gene. In contrast, no isolates were positive for the presence of bla KPC, bla IMP, and bla VIM. Virulence factor genes including iucB, iutA, iroN, kfu, allS, fimH, ybtS, mrkD, and entB were carried by 24%, 46.2%, 25%, 11.5%, 17.3%, 86.5%, 75%, 88.5%, and 100% isolates, respectively. This study evaluated the distribution and prevalence of virulence factor genes among K. pneumoniae isolates. The treatment of these infections is challenging due to the existence of particular virulence factors and the rise of antibiotic resistance. Therefore, the current study accentuates the necessity of finding new and efficient solutions for stopping the increase of antibiotic resistance.

Molecular epidemiology of carbapenem-resistant Acinetobacter baumannii isolates in Turkiye: Systematic review.

The World Health Organization has designated carbapenem-resistant Acinetobacter baumannii (CRAB) as a "critical" pathogen on the global priority list of antibiotic-resistant bacteria. This study aims to discuss the molecular epidemiology of CRAB isolates in Turkiye in the last 12 years and the prevalence of gene regions associated with resistance or pathogenesis using a systematic review method. Our study consists of a literature search, determination of eligibility and exclusion criteria, qualitative analysis of studies, data extraction, and statistical analysis. All studies were analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Guidelines. The incidence rates of blaOXA-23, blaOXA-23-like, blaOXA-24/40, blaOXA-24/40-like, blaOXA-51, blaOXA-51-like, blaOXA-58, and blaOXA-58-like genes in CRAB strains were 76.4%, 68.6%, 1.2%, 3.4%, 97.0%, 98.6%, 8.4%, and 17.1%, respectively. It was determined that the prevalence of the blaOXA-23 and blaOXA-58 gene regions showed a statistically significant change over the years. Due to the high prevalence of A. baumannii strains carrying the blaOXA-23 variant, it is necessary to follow its geographical distribution and transposon and plasmid movements. Based on available data, molecular surveillance of CRAB strains should be standardized. In addition, sterilization and disinfection processes applied within the scope of an effective struggle against CRAB strains that can remain live on surfaces for a long time should be reviewed frequently.

In vitro Activity of Cefiderocol and Ceftazidime-Avibactam, Against Carbapenemase-Producing Enterobacterales

Carbapenemase production is an issue of significant clinical and public health concern, because of the shortage of effective antimicrobial agents available for treatment. Here, we present antimicrobial susceptibility data of ceftazidime-avibactam, cefiderocol, and other clinically relevant antibiotics for carbapenemase-producing Enterobacterales bloodstream isolates, in accordance with European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. A total of 133 carbapenemase producing Enterobacterales bloodstream isolates from May 2010 to September 2018 were included in the study. Species were identified using matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (Bruker Daltonics, Germany). The presence of the blaKPC, blaNDM, blaOXA-48, blaVIM, and blaIMP carbapenemase genes were investigated by BD Max CRE assay (Becton Dickinson, USA) and in-house PCR. Antimicrobial susceptibility testing was performed by the BD Phoenix automated system (Becton Dickinson, USA), except cefiderocol and colistin. Cefiderocol and colistin susceptibility was determined by disk diffusion and broth microdilution method, respectively. Except for cefiderocol and ceftazidime-avibactam, the percentage of susceptible isolates did not exceed 90% for any of the antibiotics tested. Although none of the isolates were resistant to cefiderocol, the ceftazidime-avibactam resistance rate was 9.8%. All of the ceftazidime-avibactam resistant strains were NDM (New Delhi metallo-beta-lactamases) producers. Among the other clinically relevant antibiotics tested, only amikacin, colistin, tigecycline, and fosfomycin susceptibility rates exceeded 50%. Of the 133 isolates 22.6% were resistant to colistin which is the preferred antibiotic with a second active agent for infections caused by metallo-beta-lactamase producing Enterobacterales in Turkey. In our study, resistance to ceftazidime-avibactam was detected only in metallo-beta-lactamase producing Enterobacterales isolates, while cefiderocol was found to be effective against all strains. It is important to monitor regional antimicrobial susceptibility data, as the emergence of antimicrobial resistant phenotypes is directly linked to the use of any given antimicrobial agent.

Phenotypic and genotypic detection of carbapenemase-producing Escherichia coli and Klebsiella pneumoniae in Accra, Ghana.

To describe the occurrence of carbapenem resistance among multidrug-resistant (MDR) Escherichia coli and Klebsiella pneumoniae isolated from clinical specimens in Accra using phenotypic and genotypic methods. The study was cross-sectional, involving 144 clinical MDR E. coli and K. pneumoniae isolates recovered from the Central Laboratory of the Korle Bu Teaching Hospital (KBTH). The isolates were re-cultured bacteriologically, identified using standard biochemical tests, and subjected to antibiotic susceptibility testing using the Kirby-Bauer method. Carbapenem resistance was determined based on imipenem, meropenem, and ertapenem zones of inhibition, as well as minimum inhibitory concentrations (MICs). Carbapenemase production was determined phenotypically by modified Hodge test (MHT) and modified carbapenem inactivation method (mCIM), and genotypically with multiplex PCR targeting the blaKPC, blaIMP, blaNDM, blaVIM, and blaOXA-48 genes. Of the 144 MDR isolates, 69.4% were E. coli, and 30.6% were K. pneumoniae. The distribution of antimicrobial resistance rates among them was ampicillin (97.2%), cefuroxime (93.1%), sulfamethoxazole-trimethoprim (86.8%), tetracycline (85.4%), cefotaxime and cefpodoxime (77.1% each), amoxicillin-clavulanate (75%), ceftriaxone (73.6%), ciprofloxacin (70.8%), levofloxacin (66.0%), cefepime (65.3%), ceftazidime (64.6%), gentamicin (48.6), piperacillin-tazobactam (40.3%), cefoxitin (14.6%), amikacin (13.9%), ertapenem and meropenem (5.6% each), and imipenem (2.8%). In total, 5.6% (8/144) of them were carbapenem-resistant (carbapenem MIC range = 0.094-32.0 μg/ml), with 75% (6/8) of these testing positive by the phenotypic tests and 62.5% (5/8) by the genotypic test (of which 80% [4/5] carried blaOXA-48 and 20% (1/5) blaNDM). The blaVIM, blaIMP, and blaKPC genes were not detected. Although the rates of antibiotic resistance among the isolates were high, the prevalence of carbapenemase producers was low. The finding of blaOXA-48 and blaNDM warrants upscaling of antimicrobial resistance surveillance programmes and fortification of infection prevention and control programmes in the country.

Investigation of Antibiotic Resistance Profiles and Carbapenemase Resistance Genes in Acinetobacter Baumannii Strains Isolated From Clinical Samples

Objective: Acinetobacter baumannii is an important pathogen that can develop multiple drug resistance. Here, we aimed to investigate the antibiotic resistance profiles of A. baumannii strains isolated from the various clinics of our hospital and determine the class D beta-lactamase resistance genes causing carbapenem resistance. Methods: Between June-2016 and June-2017, 157 A. baumannii strains isolated from clinical specimens of our hospital were identified with automatic bacterial identification system and antibiograms were determined by the same system. Among the carbapenem resistant strains, blaOXA-51, blaOXA-58, blaOXA-23 and blaOXA-24 genes were also investigated by PCR method. Results: When we analyze the resistance profiles of the strains, we observed that the lowest resistance rate was against colistin with 5 (3.2%) strains. OXA-51 and OXA-23 genes were found positive in all isolates, while OXA-24 was found positive in 16 (32%) strains; OXA-58 was not detected in any of the strains. Conclusion: The most effective antibiotics for carbapenem resistant A. baumannii isolates were colistin, tigecycline and amikacin. Prevelance of OXA-24 enzyme gene was found higher than other similar studies. Monitoring antibiogram profiles and conducting molecular epidemiological studies may help us detect resistant bacteria at the source and reduce the development of resistance.

High Prevalence of blaOXA-48 and blaNDM-Producing Carbapenem-Resistant Klebsiella pneumoniae Isolated from Clinical Samples in Shahid Rajaei Hospital in Tehran, Iran

Background: Due to the increasing antibiotic resistance, treating infections caused by Klebsiella pneumoniae has become more challenging. Objectives: The present study aimed to investigate the prevalence of blaOXA-48 and blaNDM producing carbapenem-resistant K. pneumoniae isolated from clinical samples in Shahid Rajaei hospital in Tehran, Iran. Methods: Various clinical samples were collected from 1,186 patients admitted with open heart surgery in two wards (ICU and surgery) in Shahid Rajaei Heart Hospital in Tehran, Iran. Klebsiella pneumoniae isolates were identified by standard microbiologic tests. Antimicrobial susceptibility of isolates were determined by disk diffusion and E-test methods. A modified carbapenem inactivation method (mCIM) was performed to detect the presence of carbapenemase. Antibiotic resistance genes were detected using conventional polymerase chain reaction (PCR) by primers targeting blaOXA-48, blaSPM, blaIMP, blaVIM, and blaNDM genes. Results: A total of 131 clinical isolates of K. pneumoniae were isolated and 45.8% (60/131) of them were resistant to carbapenem. Klebsiella pneumoniae isolates showed the highest resistance rate (100%) to ceftriaxone, ceftazidime, cefazolin, and cefepime and the maximum sensitivity to tigecycline (96.7%). The carbapenemase-encoding blaOXA-48 and blaNDM-1 genes were detected in 96.7% and 66.7% of isolates, respectively. Eight different clusters of the isolates, considering a ≥ 80% homology cut-off, were shown with the same rep-PCR pattern. Clusters A, B, C, D, E, F, G, and H included 20, 11, 7, 6, 6, 3, 2, and 2 members, respectively. Conclusions: The RAPD-PCR method reveals the clonal relationship between isolates and may help improve infection control procedures.

Comparative genomic analysis of plasmids harboring bla OXA-48-like genes in Klebsiella pneumoniae.

The emergence and spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) is a serious medical problem worldwide. Acquired OXA-48-like carbapenemases encoded by plasmids are important causes of carbapenem resistance in K. pneumoniae. To explore the links between plasmids and bla OXA-48-like genes in K. pneumoniae, we systematically analyzed the variants of bla OXA-48-like plasmid replicon types, phylogenetic patterns, geographic distribution, conjugative transfer regions, and the genetic environments surrounding bla OXA-48-like of 191 bla OXA-48-like-harboring plasmids, which were identified from 4451 plasmids of K. pneumoniae downloaded from GenBank. Our results showed that seven different variants of bla OXA-48-like genes were identified from the 191 bla OXA-48-like-harboring plasmids in K. pneumoniae, with bla OXA-48, bla OXA-232, and bla OXA-181 being highly prevalent. In K. pneumoniae, bla OXA-48 was mainly carried by the composite transposon Tn1999.2 located on IncL/M-type conjugative plasmids, which were mainly geographically distributed in Switzerland, Germany, and China. In K. pneumoniae, the blaOXA-232 gene was mainly carried by 6.1-kb ColKP3-type mobilizable plasmids, which were mainly isolated in India. In K. pneumoniae, bla OXA-181 was mainly carried by a group of 50-kb ColKP3-IncX3 hybrid conjugative plasmids and a group of small ColKP3-type mobilizable plasmids with lengths of 5.9-9.3 kb, the former was sporadically discovered in China, South Korea, India, and Czech Republic, while the latter was almost all isolated in India. In addition, five bla OXA-245-harboring 65.9-kb IncL plasmids of K. pneumoniae isolated in Spain were found to have the genetic context of bla OXA-245 more complicated than that of bla OXA-48-harboring IncL/M-type plasmids, with two copies of IS1R inserted both upstream and downstream of bla OXA-245-lysR. These findings enhance our understanding of the genetic diversity of bla OXA-48-like-harboring plasmids in K. pneumoniae.

Characterization of Acinetobacter baumannii Isolated from Raw Milk.

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen associated with nosocomial infections. In this study, 100 raw milk samples were collected from Qena, Egypt, and subjected to conventional and molecular assays to determine the presence of A. baumannii and investigate their antimicrobial resistance and biofilm formation. Our findings revealed that, among the 100 samples, Acinetobacter spp. were found in 13 samples based on CHROM agar results. We further characterized them using rpoB and 16S-23SrRNA sequencing and gyrB multiplex PCR analysis and confirmed that 9 out of the 13 Acinetobacter spp. isolates were A. baumannii and 4 were other species. The A. baumannii isolates were resistant to β-lactam drugs, including cefotaxime (44%), ampicillin-sulbactam and levofloxacin (33.3% for each), imipenem, meropenem and aztreonam (22.2% for each). We observed different antimicrobial resistance patterns, with a multi-antibiotic resistant (MAR) index ranging from 0.2 to 0.3. According to the PCR results, blaOXA-51 and blaOXA-23 genes were amplified in 100% and 55.5% of the A. baumannii isolates, respectively, while the blaOXA-58 gene was not amplified. Furthermore, the metallo-β-lactamases (MBL) genes blaIMP and blaNDM were found in 11.1% and 22.2% of isolates, respectively, while blaVIM was not amplified. Additionally, eight A. baumannii isolates (88.8%) produced black-colored colonies on Congo red agar, demonstrating their biofilm production capacity. These results showed that, besides other foodborne pathogens, raw milk should also be examined for A. baumannii, which could be a public health concern.

2048. Molecular Characterization and Resistance Factors of Circulating Acinetobacter baumannii isolates in South-East Michigan

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAb) is increasing due to widespread use of antibiotics. Multidrug resistant (MDR) CRAb is a major threat to public health as treatment options are limited. The objective of this study is to elucidate the molecular epidemiology of circulating antibiotic resistance genes causing MDR CRAb infections by using a combination of whole-genome Multi-Locus Sequence Typing (wgMLST) and antibiotic susceptibility phenotyping. Table 1.Molecular characterization of MDR CRAb isolates*The numbers indicate % of sequence identity match for each Beta-lactamase gene. Methods Bacterial isolates were derived from cultures taken from subjects 48 hours following admission as part of routine clinical care for patients between 2017-2020. Isolates were obtained from 16 hospital units (both ICU and non-ICU) across two hospitals in the Detroit area. Whole Genome Sequencing (WGS) was performed using Illumina MiniSeq or Nextseq. WgMLST analysis was performed using BioNumerics software v7.6. ResFinder software was used for analysis of antibiotic resistance genes. Isolates underwent antibiotic susceptibility testing using a broth microdilution method (VITEK2) and Clinical &amp; Laboratory Standards Institute (CLSI) minimum inhibitory concentration (MIC) cut offs. Results Out of the 95 total isolates, 51(54%) were CRAb isolates and of the CRAb isolates, 21(41%) were MDR CRAb. WgMLST identified that majority of the circulating MDR CRAb isolates belonged to ST2Pas (ST195Ox and ST208Ox) based on CDC definitions (Table 1). MDR CRAb isolates were resistant to 3 different classes of antibiotics including aminoglycosides, fluroquinolones and β-lactams. β-lactamase genes present include (blaADC-25, blaOXA-23, blaOXA-66 and blaTEM1D) for both ST195Ox and ST208Ox and (blaADC-25, blaOXA-23 and blaOXA-223) for ST406Pas (ST310Ox). Among the patients with MDR CRAb infections, most were males with respiratory infections in a non-ICU setting. Conclusion The study demonstrated a high proportion of isolates belonged to ST2 Pas carrying multiple beta-lactamase genes including blaOXA-23 gene. ST406Pas might be an emerging lineage carrying the blaOXA-23 gene. In addition to stringent infection control measures, continuous surveillance is recommended in limiting the spread of MDR CRAb isolates in the healthcare settings. Disclosures Chetan Jinadatha, MD, MPH, AHRQ R01 Grant-5R01HS025598: Grant/Research Support|EOS Surfaces: Copper Coupons and materials for testing Keith S. Kaye, MD, MPH, Allecra: Advisor/Consultant|GlaxoSmithKline plc.: Receiving symposia honoraria|GlaxoSmithKline plc.: GlaxoSmithKline plc.-sponsored study 212502|Merck: Advisor/Consultant|qpex: Advisor/Consultant|Shionogi: Grant/Research Support|Spero: Advisor/Consultant Piyali Chatterjee, PhD, AHRQ Grant # 1R03HS027667-01: Grant/Research Support|AHRQ Grant # 1R03HS027667-01: Central Texas Veterans Health Care System.