Resistant Acinetobacter Baumannii Research Articles

Insertion Sequences within Oxacillinases Genes as Molecular Determinants of Acinetobacter baumannii Resistance to Carbapenems-A Pilot Study.

Carbapenem-resistant Acinetobacter baumannii is one of the major problems among hospitalized patients. The presence of multiple virulence factors results in bacteria persistence in the hospital environment. It facilitates bacterial transmission between patients, causing various types of infections, mostly ventilator-associated pneumonia and wound and bloodstream infections. A. baumannii has a variable number of resistance mechanisms, but the most commonly produced are carbapenem-hydrolyzing class D β-lactamases (CHDLs). In our study, the presence of blaOXA-23, blaOXA-40 and blaOXA-51 genes was investigated among 88 clinical isolates of A. baumannii, including 53 (60.2%) strains resistant to both carbapenems (meropenem and imipenem) and 35 (39.8%) strains susceptible to at least meropenem. Among these bacteria, all the isolates carried the blaOXA-51 gene. The blaOXA-23 and blaOXA-40 genes were detected in two (5.7%) and three (8.6%) strains, respectively. Among the OXA-23 carbapenemase-producing A. baumannii strains (n = 55), insertion sequences (ISAba1) were detected upstream of the blaOXA-23 gene in fifty-two (94.5%) carbapenem-resistant and two (3.6%) meropenem-susceptible isolates. A. baumannii clinical strains from Poland have a similar antimicrobial resistance profile as those worldwide, with the presence of ISAba1 among blaOXA-23-positive isolates also being quite common. Carbapenem resistance among A. baumannii strains is associated with the presence of CHDLs, especially when insertion sequences are present.

Prediction of tissue exposures of polymyxin-B, amikacin and sulbactam using physiologically-based pharmacokinetic modeling.

The combination antimicrobial therapy consisting of amikacin, polymyxin-B, and sulbactam demonstrated in vitro synergy against multi-drug resistant Acinetobacter baumannii. The objectives were to predict drug disposition and extrapolate their efficacy in the blood, lung, heart, muscle and skin tissues using a physiologically-based pharmacokinetic (PBPK) modeling approach and to evaluate achievement of target pharmacodynamic (PD) indices against A. baumannii. A PBPK model was initially developed for amikacin, polymyxin-B, and sulbactam in adult subjects, and then scaled to pediatrics, accounting for both renal and non-renal clearances. The simulated plasma and tissue drug exposures were compared to the observed data from humans and rats. Efficacy was inferred using joint probability of target attainment of target PD indices. The simulated plasma drug exposures in adults and pediatrics were within the 0.5 to 2 boundary of the mean fold error for the ratio between simulated and observed means. Simulated drug exposures in blood, skin, lung, and heart were consistent with reported penetration ratio between tissue and plasma drug exposure. In a virtual pediatric population from 2 to <18 years of age using pediatric dosing regimens, the interpretive breakpoints were achieved in 85-90% of the population. The utility of PBPK to predict and simulate the amount of antibacterial drug exposure in tissue is a practical approach to overcome the difficulty of obtaining tissue drug concentrations in pediatric population. As combination therapy, amikacin/polymyxin-B/sulbactam drug concentrations in the tissues exhibited sufficient penetration to combat extremely drug resistant A. baumannii clinical isolates.

Nosocomial carbapenem-drug resistant Acinetobacter baumannii, related factors and clinical outcomes in Northeast Iran

Background and objectivesNosocomial infections, including drug-resistant Acinetobacter baumannii infections, continue to impact the health of hospitalized patients. This study sought to determine the prevalence of these infections and assess the associated risk factors and clinical outcomes in Gorgan, Iran.MethodsA retrospective cross-sectional study was conducted on 143 infected patients with Acinetobacter baumannii in two educational hospitals in Gorgan city, Iran between 2016 and 2018. Patient information including age, gender, reason and duration of hospitalization, background of diseases, type of sample culture, symptoms, laboratory findings, prescribed antibiotics, and antibiogram were collected and analyzed. The Logistic regression and survival statistical methods were used by software of SPSS 26.ResultsA total of 37 patients (25.87%) died during hospitalization. The less than one year and 45–65 years age groups demonstrated more deaths (29.7%; p-value < 0.001). Being single (not being married) was found to be a risk factor in increasing the chance of death among patients (OR = 2.154, 95% CI: 1.02–4.53; p = 0.048). Hospitalization in intensive care units (ICUs) was a risk factor for the death of patients (OR = 4.655, 95% CI: 7.6–83.2). The resistance to carbapenems was reported to be an important risk factor for the death of patients.ConclusionsAcinetobacter baumannii infections, particularly those resistant to carbapenems, are a significant risk for patients in ICUs and can lead to higher mortality rates.

Emergence and spread of resistant and biofilm-forming Acinetobacter baumannii in critically ill COVID-19 patients

The COVID-19 pandemic has raised concerns beyond the viral infection itself. Bacterial co-infections, particularly those involving Acinetobacter baumannii, have become a significant worry in critically ill COVID-19 patients. A. baumannii is an opportunistic pathogen that can cause nosocomial infections, especially in patients with compromised immune systems. This study investigated 36 A. baumannii isolates obtained from COVID-19 patients during a concurrent outbreak. The isolates were collected over two years through routine medical requests sent to the Clinical Microbiology laboratory. Identification of the strains was confirmed through biochemical tests, the Phoenix BD® Automated Microbiology System, and MALDI-TOF Mass Spectrometry. The study assessed the antimicrobial sensitivity of the isolates, with a specific focus on resistance to the beta-lactam group as well as aminoglycosides. The presence of specific antibiotic resistance genes (blaOXA-23, -24, -51 and -58, blaKPC, blaSHV, blaIMP, blaVIM, aac(6')-Ib, ant(3'')-Ia, and aph(3')-Ia) was investigated using PCR and Sanger DNA sequencing. Biofilm-forming capabilities of the isolates were also evaluated. The findings revealed diverse resistance profiles, with a high prevalence of resistant strains, including resistance to carbapenems. Genetic analysis suggested potential clonal spread of certain strains within the hospital setting. Moreover, a significant proportion of the isolates demonstrated strong biofilm-forming abilities, which can enhance persistence and antibiotic resistance. In conclusion, this study highlights the need for vigilant monitoring and targeted interventions to address bacterial co-infections in COVID-19 patients. The diversity in resistance patterns, potential clonal spread, and robust biofilm-forming abilities among A. baumannii isolates underscore the importance of addressing this issue to better manage and treat critically ill COVID-19 patients.

Effect of colistin combined with sulbactam: 9 g versus 12 g per day on mortality in the treatment of carbapenems resistant Acinetobacter baumannii pneumonia: a randomized controlled trial.

The current treatment recommendation involves administering a high dose of sulbactam alongside at least one additional agent. However, there remains a lack of data regarding the optimal dosage of sulbactam. We investigated whether administering sulbactam at a dosage of 12 g/day decreases the mortality rate among patients with CRAB pneumonia compared to 9 g/day. The study was an open-label, superiority, randomized controlled trial conducted at Phramongkutklao Hospital between September 2019 and September 2023 in patients diagnosed with CRAB. Participants were randomly assigned to receive a combination of colistin with either 9 or 12 g/day of sulbactam. The primary endpoint was the all-cause mortality rate at 28 days post-randomization. Among the 138 participants, there was a trend toward a lower mortality rate in the 12 g/day group (59.4% vs. 47.8%; p = 0.158). After adjusting for factors associated with mortality, a lower mortality was observed in the 12 g/day group (adjusted HR 0.54 [95% CI 0.33-0.87]; p = 0.0110). The microbiological cure rate at day 7 was higher in the 12 g/day group (73.2% vs. 89.4%; p = 0.02). Colistin in combination with sulbactam at a dosage of 12 g/day may improve mortality compared to 9 g/day.

Analysis of antimicrobial resistance and genetic diversity of Acinetobacter baumannii in a tertiary care hospital in Haikou City.

This study addresses the distribution and antimicrobial resistance of Acinetobacter baumannii (A. baumannii) in a medical facility in Haikou City, aiming to provide essential insights for enhancing in-hospital treatment and prevention strategies. We conducted a retrospective analysis of 513 A. baumannii isolates collected from a tertiary care hospital in Haikou between January 2018 and December 2020, focusing on their antimicrobial resistance patterns. Random Amplified Polymorphic DNA (RAPD) analysis was performed on 48 randomly selected A. baumannii strains. Using Gel-pro4.0 and NTSYSspc2.10 software, we constructed dendrograms to assess the genetic diversity of these strains. Our results indicate that males between 60 and 70 years old are particularly vulnerable to A. baumannii infections, which are most frequently detected in sputum samples, with a detection rate exceeding 70%. Alarmingly, over 50% of the isolates were identified as multi-drug resistant. The RAPD-PCR fingerprinting cluster analysis demonstrated substantial genetic diversity among the strains. Using primer OPA-02 at a 45% similarity coefficient, the strains were categorized into four groups (A-D), with group A being predominant (39 strains). high-prevalence areas like the Neurosurgery and Intensive Care Medicine Wards require enhanced surveillance and targeted interventions to manage Group C infections effectively. Additionally, the varied presence of other groups necessitates customized strategies to address the specific risks in each ward. Similarly, primer 270 at a 52% similarity coefficient classified the strains into five groups (E-I), with group E being most common (36 strains). The study highlights a concerning prevalence of antimicrobial resistance, particularly multi-drug resistance, among A. baumannii strains in the Haikou hospital. The significant genetic diversity, especially within groups A and E, underscores the need for tailored hospital treatment protocols and prevention measures. These findings contribute to the growing body of research on antimicrobial resistance, emphasizing the urgent need for effective management strategies in healthcare settings.

Repurposing FDA-approved drugs for combating tigecycline resistance in Acinetobacter baumannii: in silico screening against BaeR protein.

Acinetobacter baumannii is becoming a gravely threatening nosocomial infection with a higher mortality rate. The present study targets the BaeR protein that mediates resistance to tigecycline antibiotics. The BaeR protein, along with the aid of BaeS, senses the incoming antibiotics and stimulates the expression of resistance proteins. These resistance proteins efflux the antibiotics and protect the cells from its effect. The main goal of the current study is to determine potential inhibitors from already existing FDA-approved drugs that could mitigate the BaeR protein. A range of in silico approaches, including molecular dynamics, virtual screening, SIFT analysis, ADMET, DFT, MM/GBSA, MMPBSA and per residue interaction analysis, were performed to identify inhibitors against this protein. The screening of FDA-approved compounds against the BaeR protein yielded 620 compounds. These compounds were clustered by SIFT to distinguish related compounds, it resulted in 20 different clusters. The top five clusters that can accommodate the binding site with better interaction and score by fulfilling all criteria were selected. The DFT analysis showed a smaller energy gap among all the compounds, indicating the ability of the compound to form firm interactions. All the compounds showed less binding free energy in both MM/GBSA and MM/PBSA analyses. The compounds were observed to be stable throughout the simulation. The per-residue interaction analysis confirmed that interactions with binding site residues were stable throughout the simulation. As a result of the study, four compounds, namely ZINC000003801919, DB01203, DB11217 and ZINC0000000056652, were identified as efficient candidates to deal with antimicrobial resistance in A. baumannii.

Environmental contamination with carbapenem resistant Acinetobacter baumannii in healthcare settings in Fiji: a potential source of infection.

There are multiple ongoing outbreaks of carbapenem resistant Acinetobacter baumannii (CRAb) infection in Fiji's hospitals. CRAb is able to colonize and persist on various hospital surfaces for extended periods. We conducted a study to understand the extent of hospital environmental contamination and phylogenetic links with clinical isolates. Swabs were collected from high-touch surfaces at Colonial War Memorial Hospital (CWMH) September 2021 and December 2022; Lautoka Hospital (LTKH) August 2022; and Labasa Hospital (LBSH) November 2022. All bacterial isolates were identified, and antimicrobial susceptibility testing (AST) performed; isolates resistant to carbapenems and producing a carbapenemase underwent whole genome sequencing. Comparison was made to clinical isolates obtained from CWMH in 2016-2017 and 2019-2021 and from LTKH and LBSH from 2020-2021. From the 180 environmental samples collected, ten (5.6%) CRAb were isolated; no other carbapenem-resistant gram-negative organisms were isolated. Seven (70%) of the CRAb were isolated from CWMH and three (30%) from LTKH; no CRAb were isolated from LBSH. Of the seven CWMH CRAb, two were sequence type 2 (ST2), three ST25, and two ST499. All LTKH isolates were ST499. The two environmental CRAb ST2 isolates were closely genetically linked to isolates obtained from patients in CWMH, LTKH, and LBSH 2020-2021. Similarly, the three environmental CRAb ST25 isolates were closely genetically linked to isolates obtained from patients admitted to CWMH in 2019-2021 and LBSH in 2020. The environmental CRAb ST499 isolates represented two distinct clones, with clone 1 comprising two genetically identical isolates from CWMH and clone 2 the three isolates from LTKH. Although no genetic linkages were observed when comparing environmental ST499 isolates to those from CWMH patients in 2020-2021, both clone 1 isolates were genetically identical to an isolate obtained from a patient admitted during the sampling period. Our study highlights the contamination of high-touch surfaces within Fiji hospitals with CRAb, suggesting that these may serve as important sources for CRAb. Phylogenetic linkages to CRAb isolated from patients since 2019 underscores the persistence of this resistant pathogen in hospital settings and the ongoing risk for hospital-acquired infections.

Manipulation of natural transformation by AbaR-type islands promotes fixation of antibiotic resistance in Acinetobacter baumannii

The opportunistic pathogen Acinetobacter baumannii, carries variants of A. baumannii resistance islands (AbaR)-type genomic islands conferring multidrug resistance. Their pervasiveness in the species has remained enigmatic. The dissemination of AbaRs is intricately linked to their horizontal transfer via natural transformation, a process through which bacteria can import and recombine exogenous DNA, effecting allelic recombination, genetic acquisition, and deletion. In experimental populations of the closely related pathogenic Acinetobacter nosocomialis, we quantified the rates at which these natural transformation events occur between individuals. When integrated into a model of population dynamics, they lead to the swift removal of AbaRs from the population, contrasting with the high prevalence of AbaRs in genomes. Yet, genomic analyses show that nearly all AbaRs specifically disrupt comM, a gene encoding a helicase critical for natural transformation. We found that such disruption impedes gene acquisition, and deletion, while moderately impacting acquisition of single nucleotide polymorphism. A mathematical evolutionary model demonstrates that AbaRs inserted into comM gain a selective advantage over AbaRs inserted in sites that do not inhibit or completely inhibit transformation, in line with the genomic observations. The persistence of AbaRs can be ascribed to their integration into a specific gene, diminishing the likelihood of their removal from the bacterial genome. This integration preserves the acquisition and elimination of alleles, enabling the host bacterium-and thus its AbaR-to adapt to unpredictable environments and persist over the long term. This work underscores how manipulation of natural transformation by mobile genetic elements can drive the prevalence of multidrug resistance.

Exploiting human immune repertoire transgenic mice for protective monoclonal antibodies against antimicrobial resistant Acinetobacter baumannii

The use of monoclonal antibodies for the control of drug resistant nosocomial bacteria may alleviate a reliance on broad spectrum antimicrobials for treatment of infection. We identify monoclonal antibodies that may prevent infection caused by carbapenem resistant Acinetobacter baumannii. We use human immune repertoire mice (Kymouse platform mice) as a surrogate for human B cell interrogation to establish an unbiased strategy to probe the antibody-accessible target landscape of clinically relevant A. baumannii. After immunisation of the Kymouse platform mice with A. baumannii derived outer membrane vesicles (OMV) we identify 297 antibodies and analyse 26 of these for functional potential. These antibodies target lipooligosaccharide (OCL1), the Oxa-23 protein, and the KL49 capsular polysaccharide. We identify a single monoclonal antibody (mAb1416) recognising KL49 capsular polysaccharide to demonstrate prophylactic in vivo protection against a carbapenem resistant A. baumannii lineage associated with neonatal sepsis mortality in Asia. Our end-to-end approach identifies functional monoclonal antibodies with prophylactic potential against major lineages of drug resistant bacteria accounting for phylogenetic diversity and clinical relevance without existing knowledge of a specific target antigen. Such an approach might be scaled for a additional clinically important bacterial pathogens in the post-antimicrobial era.

Dissemination of NDM-mediated carbapenem resistance in biofilm-forming Acinetobacter baumannii in some Egyptian hospitals

Dissemination of NDM-mediated carbapenem resistance in biofilm-forming Acinetobacter baumannii in some Egyptian hospitals

Resensitization to colistin results in rapid and stable recovery of adherence, serum resistance and ompW in Acinetobacter baumannii.

Colistin resistance in Acinetobacter baumannii is an emerging problem that limits antimicrobial therapy options. We isolated two pairs of colistin susceptible and colistin-resistant A. baumannii (K1007/K1006 and K408/K409) from two patients diagnosed with carbapenem-resistant A. baumannii infection. Colistin susceptible isolates were exposed to in vitro colistin induction for 50 generations. The selected cell populations were subjected to DNA and RNA sequencing and phenotypic assays. In the in vitro induction assay, K408 gained colistin resistance on the corresponding day of clinical resistance (K408-G25) and got resensitized to colistin in the consecutive generation (K408-G26). A significant upregulation of ompW, ata, adeFGH genes on K408-G25 was followed by a downregulation upon resensitization to colistin (G26). Despite the upregulation of the ompW gene in transcriptomic analysis, the ompW protein disappeared on K408-G25 and recovered in the resensitized generation (G26). In parallel, disrupted cell membrane integrity recovered in K408-G26. In the K408-G25, downregulation of pbpG and upregulation of pbp1a/pbp3 genes decreased serum-resistance which was reversed in the resensitized generation (G26). The K1007 did not gain colistin resistance amongst 50-generations, however, the generation corresponding to clinical resistance day (K1007-G9) had a similar trend with K408-G25. The clinical colistin-resistant K409 and K1006 had SNPs on pmrA and pmrB genes. In this study, we observed that A. baumannii regulates adhesion, efflux pumps and serum-resistance associated genes as an early response to colistin stress. Besides, the ompW protein disappears in the cell membrane of colistin resistant cells which recovers after resensitization to colistin. The lack of ompW protein in colistin-resistant cells should be taken into consideration for escape mutants in development of antivirulence vaccination or treatment options.

Colorimetric Loop-Mediated Isothermal Amplification Assays Accurately Detect blaOXA-23-like and ISAba1 Genes from Acinetobacter baumannii in Pure Cultures and Spiked Human Sera.

Carbapenem resistance in Acinetobacter baumannii is a critical global health threat attributed to transferrable carbapenemase genes. Carbapenemase genotyping using polymerase chain reaction (PCR) presents a challenge in resource-limited settings because of its technical requirements. This study designed new loop-mediated isothermal amplification (LAMP) primers using multiple sequence alignment-based workflows, validated the primer performance against multiple target variants in silico, and developed novel LAMP assays (LAntRN-OXA23 and LAntRN-ISAba1) to detect the transferable blaOXA-23-like carbapenemase genes and ISAba1 elements in pure cultures and A. baumannii-spiked serum samples. The designed LAMP primers bind to the conserved regions of their highly polymorphic targets, with their in silico performance comparable with other published primers. The in vitro LAMP assays (using 30 PCR-profiled A. baumannii and 10 standard multidrug-resistant gram-negative isolates) have 100% concordance with the PCR-positive clinical samples, limits of detection as low as 1 pg/µL (200 copies/µL), and specificities of 57.89-100%. Both assays produced positive results when testing DNA samples (extracted using a commercial kit) from blaOXA-23-like and ISAba1-blaOXA-51-like PCR-positive A. baumannii-spiked normal human sera (five set-ups per target). In summary, the LAMP assays accurately detected the target genes and have applications in infection management, control, and point-of-care testing in resource-limited healthcare settings.

Acinetobacter baumannii transformants expressing oxacillinases and metallo-β-lactamases that confer resistance to meropenem: new tools for anti-Acinetobacter drug development and AMR preparedness.

Antimicrobial resistance (AMR) in Acinetobacter baumannii is an unmet medical need. Multiple drug-resistant/extremely drug-resistant strains of A. baumannii do not display growth well in in vivo models, and consequently, their response to antibacterial therapy is inconsistent. We addressed this issue by engineering carbapenem resistance motifs into the highly virulent genetic background of A. baumannii AB5075. This strain has a chromosomally encoded oxa-23 that was deleted (Δoxa-23), then plasmids expressing oxa-23, oxa-24/40, oxa-58, imp-1, vim-2, and ndm-1 were introduced to create the mutant strains. Each transformant was used as a challenge strain in a neutropenic murine thigh infection model and assessed for the extent of growth and response to meropenem 200 mg/kg subcutaneously every 6 h (q6h). Pharmacodynamic analyses were performed by transforming drug exposure from dose (mg/kg) to the fraction of the dosing interval; free meropenem concentrations were >minimum inhibitory concentration (MIC) (fT > MIC). AB5075 and the AB5075Δoxa-23 mutant had a MICs of 32 and 4 mg/L, respectively. The transformants harboring oxacillinases oxa-24/40 and oxa-58 had an MIC of 64 mg/L. The metallo-β-lactamases imp-1, vim-2, and ndm-1 had MICs of 128, 64, and 64 mg/L, respectively. All vehicle-treated transformants displayed in vivo growth in the range of 0.75-1.4 log. The response to meropenem was consistent with the varying fT > MIC of the transformants and was readily described by an inhibitory sigmoid Emax relationship. Stasis was achieved with a fT > MIC of 0.36. These A. baumannii transformants are invaluable new tools for the assessment of anti-Acinetobacter compounds and provide a new pathway for AMR preparedness.

Comparison of Beta-Lactamase Profiles and Epidemiology of Multi-Drug Resistant Acinetobacter baumannii Isolates in Southwest Turkey: 2011 vs. 2019 Study

Background: The most significant problem encountered with hospital infections caused by multi-drug resistant Acinetobacter baumannii isolates is the difficulty in treatment. Defining resistance mechanisms is important for the development of treatment strategies. Objectives: The aim of this study was to investigate the beta-lactamase genes and clonal relationship in multi-drug resistant A. baumannii isolates in Mugla, Turkey, as no data are currently available for this province. Methods: Total 96 multi-drug resistant A. baumannii isolates obtained from hospitalized patients, between 2011 - 2012 period (n = 61) and in year 2019 (n = 35) were investigated and compared for antibiotic susceptibilities, beta-lactamase enzyme encoding genes by polymerase chain reaction (PCR) method. Repetitive extragenic palindromic (REP) PCR was made for dendrogram analysis to illustrate hierarchical relationship between isolates. Results: Overall, 74.0% of the isolates were obtained from patients in intensive care units. All multi-drug resistant isolates were found resistant to ciprofloxacin, piperacillin, piperacillin-tazobactam, meropenem, and imipenem by the disk diffusion method. The minimum inhibitory concentration values indicated that all isolates were resistant to imipenem, while colistin resistance was determined as 21.9%. The ISAba-I insertion element was present in all isolates. BlaOXA-23-like was present in 96.9%, and blaOXA-24-like was detected in three (3.1%) isolates. blaNDM positivity was shown in 5.2% of isolates. The indistinguishable or closely related isolates ratio was detected as 29.5% for the 2011 - 2012 period and 80% for 2019. Conclusions: Our findings showed that antibiotic resistance rates were high in A. baumannii, particularly isolated from intensive care unit patients in Mugla province. The prevalence of beta-lactamase and metallo-beta-lactamase genes has been increasing year by year, with the blaOXA-23-like gene region being the most prevalent. Additionally, the co-existence of these genes among strains is also on the rise. These findings from two different periods may provide useful reference data for future studies.

Identification of novel drug targets to counteract efflux pump mediated multidrug resistance in Acinetobacter baumannii

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii poses an escalating threat to the healthcare system worldwide. A significant factor contributing to increasing resistance is the overexpression of chromosomally encoded efflux pumps, which expel antibiotics from bacterial cells, thereby rendering treatments less effective. The efflux pumps not only mediate resistance to antibiotics through drug efflux but also work synergistically with other resistance mechanisms, thereby doubling the resistance. Despite their crucial role in antibiotic resistance, understanding of the structure, function, mechanisms of action, and regulation of efflux pumps remains limited, which is necessary for devising effective strategies to restore drug susceptibility and to combat MDR isolates. In this context, the present study evaluated the prevalence of efflux pump overexpression in clinical A. baumannii isolates using phenotypic and genotypic methods and identified potential therapeutic targets employing a network-based approach. A total of 172 A. baumannii isolates were collected and subjected to antibiotic susceptibility tests using the Kirby-Bauer disk diffusion method. All the isolates were found to be MDR, with 94.76 % showing resistance to carbapenems. Efflux pump overexpression was detected in 54.65 % of isolates using the Ethidium-Bromide Agar Cartwheel method, and efflux pump inhibitory activity was observed in 68.71 % of isolates using cyanide m-chlorophenylhydrazone (CCCP). A total of thirteen efflux pump genes were detected in the tested isolates using diagnostic PCR, which were considered for interaction network analysis using STRING. Clustering analysis of the merged network identified two highly interconnected clusters, each comprising functional partners crucial for efflux pump function and regulation. Key hub genes, including AdeB, AdeJ, AdeK, AdeC, macB, tolC, AIL80285.1, AdeR, and AdeS, were identified as primary targets due to their significant influence on the network. Additionally, 24 clustered genes were pinpointed as potential drug targets for developing novel therapeutics to combat the formidable challenge of efflux pump-mediated MDR in A. baumannii.

Intensifying inactivation strategies: Insights into the role of ultrasound on the inactivation of antibiotic resistant Acinetobacter baumannii via Photo-Fenton reaction

Improvisation of the contemporary water treatment technologies is critical not only to prevent water borne diseases but also to augment the available water sources. Here, a systematic study is effectuated to comprehend the upswing in the inactivation efficiency of Photo-Fenton (PF) chemistry induced by ultrasound (US) against antibiotic resistant (ABR) Acinetobacter baumannii (A. baumannii). Inactivation of A. baumannii (≈5×106 CFU/mL) was noticed within 75 and 105 min of US assisted PF (SPF) and PF processes respectively using 20 mg/L of H2O2 and 2 mg/L of Fe2+. It was interesting to notice that the PF reaction was effective under weak acidic condition (pH=3 and 5.5) whereas SPF process was realized over a wide pH range (3, 5.5, 7 and 9). No reactivation of the bacteria was found in both the processes till 96 h suggesting the impairment of not only the bacterial cell membrane but also the intracellular components. Experimental results although has suggested the generation of several reactive oxygen species (ROS), the inactivation mechanism was suggested to be dominated by the H2O2 and •OH. The damage caused to the bacterial cell membranes by the synergistic role of US and ROS was observed in the electron microscopy images. Comparative transcriptomic analysis has indicated the upregulation of genes regulating the LPS assembly proteins (Lpt A, B, C) and Pls B, Pgs A and Pal genes regulating the phospholipid synthesis which are known to regulate the stress induced response in bacteria. The SPF process was further validated with real water samples and the treated water was not found to have remarkable toxic effect on the in-vivo animal which endorse its candidature for future applications.

Characterization of a colistin resistant, hypervirulent hospital isolate of Acinetobacter courvalinii from Canada.

Non-baumannii Acinetobacter spp. are becoming more prevalent in clinical settings including those that present resistance to last-resort antibiotics such as colistin. AB222-IK40 is an Acinetobacter courvalinii strain isolated from the Ottawa Hospital Research Institute located in Ottawa, Canada. To our knowledge, it is the first report of clinical A. courvalinii in Canada. Based on the susceptibility profile, AB222-IK40 is resistant to colistin and non-susceptible to ertapenem. Whole-genome sequencing allowed for genomic investigation into colistin resistance mechanisms. No previously identified mechanism(s) were observed, but a mobile colistin resistance (mcr)-like gene and a UDP-glucose dehydrogenase gene were identified. Based on phylogenomic analyses, the mcr-like gene is an intrinsic phosphoethanolamine transferase. This gene family is implicated in one of the many mechanisms responsible for colistin resistance in Acinetobacter baumannii as well as Acinetobacter modestus. UDP-glucose dehydrogenase is involved in colistin resistance in Enterobacterales and has been shown to be involved in capsule formation in A. baumannii. Global lipidomics revealed greater abundance of phosphatidyl-myo-inositol and lyso-phosphatidyl ethanolamine moieties in the membrane of A. courvalinii than in A. baumannii. Lipidomic profiles showed differences that were probably responsible for the colistin resistance phenotype in AB222-IK40. This isolate was also hypervirulent based on survival assays in Galleria mellonella. As this is the first report of A. courvalinii from a hospital in Canada, this species may be an emerging clinical pathogen, and therefore, it is important to understand this mechanism of its colistin resistance and hypervirulence.

Exploring the Sequence analysis of the Two-Component System Response Regulator OmpR in Multi-Drug Resistant (MDR) Acinetobacter baumannii

Background: The study focuses on the clinical profiles, antibiotic susceptibility, and genetic characteristics of 25 A. baumannii isolates from patients with urinary tract infections (UTIs). Patient Cohort: Ages range from 18 to 70 years, with a male to female ratio of 1.375. Notable Finding: Some multidrug-resistant (MDR) isolates had commonalities with extensively drug-resistant (XDR) variations, showing the evolution of drug resistance.Methods: Antibiotic Efficacy Analysis: Evaluation of antibiotic efficacy when the variable moved from lower (Bin 1) to higher (Bin 2) levels. Correlation Matrix: An analysis of antibiotic correlations to better identify potential cross-resistance and shared characteristics. Genetic Diversity Analysis: An examination of variants in the OmpR gene, including mutations and polymorphisms. Sequence analysis is used to identify point mutations in OmpR, with an emphasis on transitions such as adenine (A) to guanine (G).Results: Significant improvement in antibiotic efficacy from Bin 1 to Bin 2. Correlation Findings: Antibiotics have complex interactions, which may indicate cross-resistance. Genetic diversity: Variations in the OmpR gene have implications for virulence and adaptability. Sequence Analysis: The majority of point mutations in OmpR were transitions, with A typically changing to G.Conclusion: In Iraq, researchers have discovered the first evidence that clinical resistance in A. baumannii may be caused by structural alterations in the OmpR gene. A. baumannii isolates' genetic diversity at certain locations suggests possible implications on virulence and adaptation.Keywords: Acinetobacter baumannii; OmpR; Polymorphism; MDR

Multidrug-resistant Acinetobacter baumannii: An underestimated pathogen in veterinary medicine in Italy

The increasing drug resistance of Acinetobacter (A.) baumannii is a growing concern globally. This bacterium, prevalent in hospitals, is responsible for multi-resistant infections and has been identified by the WHO as a priority pathogen for new antibiotic development. While there is extensive information on human isolates, data on animal isolates are scarce and fragmented based on limited clinical cases and genomic analyses. The impact of resistant strains on public and veterinary health is challenging to assess due to a lack of data. However, the potential impact on public health cannot be underestimated. Therefore, it is imperative to strengthen surveillance of A. baumannii in domestic animals, livestock, and wildlife. The growing presence of this pathogen in veterinary clinical samples is alarming, especially given the increasing interaction between animals and humans. Recognizing animals as potential reservoirs is crucial for understanding pathogen transmission dynamics, given their capacity for zoonotic transmission. With the rise in the number of animals testing positive for multi-resistant bacteria, monitoring A. baumannii in the animal population is vital to prevent the pathogen's spread and protect public health. A review of studies conducted in Italy on the topic underscores the role of pets, livestock, and foods of animal origin in the transmission of A. baumannii and Acinetobacter spp. Further animal research is urgently needed to gain a better understanding of the mechanisms of spread and resistance. This review underscores the need to explore this area, providing crucial insights for public health and infectious disease management within a One Health context.