Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

Pathogenicity and virulence of Acinetobacter baumannii: Factors contributing to the fitness in healthcare settings and the infected host

Acinetobacter baumannii is a common cause of healthcare-associated infections and hospital outbreaks, particularly in intensive care units. Much of the success of A. baumannii relies on its genomic plasticity, which allows rapid adaptation to adversity and stress. The capacity to acquire novel antibiotic resistance determinants and the tolerance to stresses encountered in the hospital environment promote A. baumannii spread among patients and long-term contamination of the healthcare setting. This review explores virulence factors and physiological traits contributing to A. baumannii infection and adaptation to the hospital environment. Several cell-associated and secreted virulence factors involved in A. baumannii biofilm formation, cell adhesion, invasion, and persistence in the host, as well as resistance to xeric stress imposed by the healthcare settings, are illustrated to give reasons for the success of A. baumannii as a hospital pathogen.

Emergence of novel hypervirulent Acinetobacter baumannii strain and herpes simplex type 1 virus in a case of community-acquired pneumonia in China

BACKGROUND

A. baumannii is an important and common clinical pathogen, especially in the intensive care unit (ICU). This study aimed to characterize one hypervirulent A. baumannii strain in a patient with community-acquired pneumonia and herpes simplex type 1 virus infection.

METHODS

Minimum inhibitory concentrations (MICs) were determined using the Kirby-Bauer (K-B) and broth microdilution methods. Galleria mellonella infection model experiment was conducted. Whole-genome sequencing (WGS) was performed using the Illumina and Nanopore platforms. The resistance and virulence determinants were identified using the ABRicate program with ResFinder and the VFDB database. The capsular polysaccharide locus (K locus) and lipooligosaccharide outer core locus (OC locus) were identified using Kleborate with Kaptive. Phylogenetic analyses were conducted using the BacWGSTdb server.

RESULTS

A. baumannii XH2146 strain belongs to ST10Pas and ST447Oxf. The strain was resistant to cefazolin, ciprofloxacin, and trimethoprim/sulfamethoxazole (TMP-SMX). Bautype and Kaptive analyses showed that XH2146 contains OCL2 and KL49. WGS analysis revealed that the strain harbored blaADC-76, blaOXA-68, ant(3'')-IIa, tet(B), and sul2. Notably, tet(B) and sul2, both were located within a 114,700-bp plasmid (designated pXH2146-1). Virulence assay revealed A. baumannii XH2146 possessed higher virulence than A. baumannii AB5075 at 12 h. Comparative genomic analysis showed that A. baumannii ST447 strains were mainly isolated from the USA and exhibited a relatively close genetic relationship. Importantly, 11 strains were observed to carry blaOXA-58; blaOXA-23 was identified in 11 isolates and three ST447 A. baumannii strains harbored blaNDM-1.

CONCLUSIONS

Early detection of community-acquired hypervirulent Acinetobacter baumannii strains is recommended to prevent their extensive spread in hospitals.

Antibacterial and anti-coronavirus investigation of selected Senegalese plant species according to an ethnobotanical survey

ETHNOPHARMACOLOGICAL RELEVANCE

In Senegal, upper and lower respiratory tract infections constitute a real health problem. To manage these disorders, most people rely on the use of local medicinal plants. This is particularly the case for species belonging to the botanical families, Combretaceae, Fabaceae, Myrtaceae and Rubiaceae, which are widely used to treat various respiratory problems such as colds, flu, rhinitis, sinusitis, otitis, angina, bronchitis, bronchiolitis and also pneumonia.

AIM OF THE STUDY

The aim of this study was to identify medicinal plants traditionally used for the management of infectious diseases, in particular those of the respiratory tract. On the basis of these ethnopharmacological uses, this study made it possible to highlight the antibacterial, antiviral and cytotoxic activities of selected plant species.

MATERIALS AND METHODS

An ethnobotanical survey was conducted in Senegal among informants, including herbalists, traditional healers, and households, using medicinal plants in the management of infectious diseases, with a focus on respiratory tract infections. The most cited plant species were evaluated in vitro on a panel of 18 human pathogenic bacteria may be involved in respiratory infections and against the human coronavirus HCoV-229E in Huh-7 cells. The antiviral activity of the most active extracts against HCoV-229E was also evaluated on COVID-19 causing agent, SARS-CoV-2 in Vero-81 cells. In parallel, cytotoxic activities were evaluated on Huh-7 cells.

RESULTS

A total of 127 informants, including 100 men (78.74%) and 27 women (21.26%) participated in this study. The ethnobotanical survey led to the inventory of 41 plant species belonging to 19 botanical families used by herbalists and/or traditional healers and some households to treat infectious diseases, with a specific focus on upper respiratory tract disorders. Among the 41 plant species, the most frequently mentioned in the survey were Guiera senegalensis J.F. Gmel. (95.2%), Combretum glutinosum Perr. Ex DC. (93.9%) and Eucalyptus spp. (82.8%). Combretaceae (30.2%) represented the most cited botanical family with six species, followed by Fabaceae (29.3%, 12 species). A total of 33 crude methanolic extracts of the 24 plant species selected for their number of citations were evaluated in vitro for their antimicrobial and cytotoxic activities. Guiera senegalensis, Combretum glutinosum, Vachellia nilotica subsp. tomentosa (Benth.) Kyal. & Boatwr, Eucalyptus camaldulensis Dehnh., and Terminalia avicennioides Guill. & Perr., showed antibacterial activities. The most active plants against HCoV-229E were: Ficus sycomorus L., Mitragyna inermis (Willd.) Kuntze, Pterocarpus erinaceus Poir., and Spermacoce verticillata L. One of these plants, Mitragyna inermis, was also active against SARS-CoV-2.

CONCLUSION

This work confirmed the anti-infective properties of plant species traditionally used in Senegal. Overall, the most frequently cited plant species showed the best antibacterial activities. Moreover, some of the selected plant species could be considered as a potential source for the management of coronavirus infections. This new scientific data justified the use of these plants in the management of some infectious pathologies, especially those of the respiratory tract.

Biological role of mitochondrial TLR4-mediated NF-κB signaling pathway in central nervous system injury

Previous studies suggested that central nervous system injury is often accompanied by the activation of Toll-like receptor 4/NF-κB pathway, which leads to the upregulation of proapoptotic gene expression, causes mitochondrial oxidative stress, and further aggravates the inflammatory response to induce cell apoptosis. Subsequent studies have shown that NF-κB and IκBα can directly act on mitochondria. Therefore, elucidation of the specific mechanisms of NF-κB and IκBα in mitochondria may help to discover new therapeutic targets for central nervous system injury. Recent studies have suggested that NF-κB (especially RelA) in mitochondria can inhibit mitochondrial respiration or DNA expression, leading to mitochondrial dysfunction. IκBα silencing will cause reactive oxygen species storm and initiate the mitochondrial apoptosis pathway. Other research results suggest that RelA can regulate mitochondrial respiration and energy metabolism balance by interacting with p53 and STAT3, thus initiating the mitochondrial protection mechanism. IκBα can also inhibit apoptosis in mitochondria by interacting with VDAC1 and other molecules. Regulating the biological role of NF-κB signaling pathway in mitochondria by targeting key proteins such as p53, STAT3, and VDAC1 may help maintain the balance of mitochondrial respiration and energy metabolism, thereby protecting nerve cells and reducing inflammatory storms and death caused by ischemia and hypoxia.

Derivation and validation of a predictive mortality model of in-hospital patients with Acinetobacter baumannii nosocomial infection or colonization

PURPOSE

Acinetobacter baumannii (Ab) is a Gram-negative opportunistic bacterium responsible for nosocomial infections or colonizations. It is considered one of the most alarming pathogens due to its multi-drug resistance and due to its mortality rate, ranging from 34 to 44,5% of hospitalized patients. The aim of the work is to create a predictive mortality model for hospitalized patient with Ab infection or colonization.

METHODS

A cohort of 140 sequentially hospitalized patients were randomized into a training cohort (TC) (100 patients) and a validation cohort (VC) (40 patients). Statistical bivariate analysis was performed to identify variables discriminating surviving patients from deceased ones in the TC, considering both admission time (T0) and infection detection time (T1) parameters. A custom logistic regression model was created and compared with models obtained from the "status" variable alone (Ab colonization/infection), SAPS II, and APACHE II scores. ROC curves were built to identify the best cut-off for each model.

RESULTS

Ab infection status, use of penicillin within 90 days prior to ward admission, acidosis, Glasgow Coma Scale, blood pressure, hemoglobin and use of NIV entered the logistic regression model. Our model was confirmed to have a better sensitivity (63%), specificity (85%) and accuracy (80%) than the other models.

CONCLUSION

Our predictive mortality model demonstrated to be a reliable and feasible model to predict mortality in Ab infected/colonized hospitalized patients.

Carbapenem-resistant Acinetobacter baumannii (CRAB): metabolic adaptation and transcriptional response to human urine (HU)

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a major human pathogen and a research priority for developing new antimicrobial agents. CRAB is a causative agent of a variety of infections in different body sites. One of the manifestations is catheter-associated urinary tract infection, which exposes the bacteria to the host's urine, creating a particular environment. Exposure of two CRAB clinical isolates, AB5075 and AMA40, to human urine (HU) resulted in the differential expression levels of 264 and 455 genes, respectively, of which 112 were common to both strains. Genes within this group play roles in metabolic pathways such as phenylacetic acid (PAA) catabolism, the Hut system, the tricarboxylic acid (TCA) cycle, and other processes like quorum sensing and biofilm formation. These results indicate that the presence of HU induces numerous adaptive changes in gene expression of the infecting bacteria. These modifications presumably help bacteria establish and thrive in the hostile conditions in the urinary tract. These analyses advance our understanding of CRAB's metabolic adaptations to human fluids, as well as expanding knowledge on bacterial responses to distinct human fluids containing different concentrations of human serum albumin (HSA).

Acinetobacter junii: an emerging One Health pathogen

Acinetobacter junii is an opportunistic human and animal pathogen severely understudied. Here, we conducted the largest genomic epidemiological study on this pathogen to date. Our data show that this bacterium has spread globally. Also, we found that some human and non-human isolates are not well differentiated from one another, implying transmission between clinical and non-clinical, non-human settings. Remarkably, human but also some non-human isolates have clinically important antibiotic resistance genes, and some of these genes are located in plasmids. Given these results, we put forward that A. junii should be considered an emerging One Health problem. In this regard, future molecular epidemiological studies about this species will go beyond human isolates and will consider animal-, plant-, and water-associated environments.

IMPORTANCE

Acinetobacter baumannii is the most well-known species from the genus Acinetobacter. However, other much less studied Acinetobacter species could be important opportunistic pathogens of animals, plants and humans. Here, we conducted the largest genomic epidemiological study of A. junii, which has been described as a source not only of human but also of animal infections. Our analyses show that this bacterium has spread globally and that, in some instances, human and non-human isolates are not well differentiated. Remarkably, some non-human isolates have important antibiotic resistance genes against important antibiotics used in human medicine. Based on our results, we propose that this pathogen must be considered an issue not only for humans but also for veterinary medicine.

Modular, inducible, and titratable expression systems for Escherichia coli and Acinetobacter baumannii

Gene expression systems that transcend species barriers are needed for cross-species analysis of gene function. In particular, expression systems that can be utilized in both model and pathogenic bacteria underpin comparative functional approaches that inform conserved and variable features of bacterial physiology. Here, we develop replicative and integrative vectors alongside a novel, IPTG-inducible promoter that can be used in the model bacterium Escherichia coli K-12 as well as strains of the antibiotic-resistant pathogen, Acinetobacter baumannii. We generate modular vectors that transfer by conjugation at high efficiency and either replicate or integrate into the genome, depending on design. Embedded in these vectors, we also developed a synthetic, IPTG-inducible promoter, P abstBR , that induces to a high level, but is less leaky than the commonly used trc promoter. We show that P abstBR is titratable at both the population and single cell level, regardless of species, highlighting the utility of our expression systems for cross-species functional studies. Finally, as a proof of principle, we use our integrating vector to develop a reporter for the E. coli envelope stress σ factor, RpoE, and deploy the reporter in E. coli and A. baumannii, finding that A. baumannii does not recognize RpoE-dependent promoters unless RpoE is heterologously expressed. We envision that these vector and promoter tools will be valuable for the community of researchers that study fundamental biology of E. coli and A. baumannii.

Characterization of antibiotic and disinfectant susceptibility in biofilm-forming Acinetobacter baumannii: A focus on environmental isolates

The clinical role of Acinetobacter baumannii has been highlighted in numerous infectious syndromes with a high mortality rate, due to the high prevalence of multidrug-resistant (MDR) isolates. The treatment and eradication of this pathogen is hindered by biofilm-formation, providing protection from noxious environmental factors and antimicrobials. The aim of this study was to assess the antibiotic susceptibility, antiseptic susceptibility and biofilm-forming capacity using phenotypic methods in environmental A. baumannii isolates. One hundred and fourteen (n = 114) isolates were collected, originating from various environmental sources and geographical regions. Antimicrobial susceptibility testing was carried out using the disk diffusion method, while antiseptic susceptibility was performed using the agar dilution method. Determination of biofilm-forming capacity was carried out using a microtiter-plate based method. Resistance in environmental A. baumannii isolates were highest for ciprofloxacin (64.03%, n = 73), levofloxacin (62.18%, n = 71) and trimethoprim-sulfamethoxazole (61.40%, n = 70), while lowest for colistin (1.75%, n = 2). Efflux pump overexpression was seen in 48.25% of isolates (n = 55), 49.12% (n = 56) were classified as MDR. 6.14% (n = 7), 9.65% (n = 11), 24.65% (n = 28) and 59.65% (n = 68) of isolates were non-biofilm producers, weak, medium, and strong biofilm producers, respectively. No significant differences were observed between non-MDR vs. MDR isolates regarding their distribution of biofilm-producers (P = 0.655). The MIC ranges for the tested antiseptics were as follows: benzalkonium chloride 16-128 μg mL-1, chlorhexidine digluconate 4-128 μg mL-1, formaldehyde 64-256 μg mL-1 and triclosan 2-16 μg mL-1, respectively. The conscientious use of antiseptics, together with periodic surveillance, is essential to curb the spread of these bacteria, and to maintain current infection prevention capabilities.

Resazurin microplate test method for rapid determination of colistin resistance in carbapenem-resistant Acinetobacter baumanii isolates

BACKGROUND

Colistin-resistant Acinetobacter baumannii isolates are extremely important pathogens for hospital-acquired infections.

OBJECTIVE

To investigate the effectiveness of the resazurin microplate assay (REMA) for the rapid determination of colistin resistance.

METHODS

Susceptibility for colistin was investigated in vitro by the broth microdilution method (BMD) and the resazurin microplate assay (REMA) on 106 carbapenem-resistant Acinetobacter baumannii isolates.

RESULTS

The results of both test methods were compared, and the categorical agreement between them was found to be 100%. No minor, major, or very major discrepancy was observed between the 2 methods.

CONCLUSIONS

The most important advantages of REMA are that the results are obtained within 6 hours compared to the reference method, that it is easy to evaluate because it is colorimetric, and that the susceptibility result can be reported to the clinician on the same day as bacterial identification.

Identification and characterization of Acinetobacter nosocomialis BfmRS, two-component regulatory system, essential for biofilm development

BACKGROUND

Biofilm development by bacteria is considered to be an essential stage in the bacterial infection. Acinetobacter nosocomialis is an important nosocomial pathogen causing a variety of human infections. However, characteristics and specific determinants of biofilm development have been poorly characterized in A. nosocomialis.

OBJECTIVE

The aim of this study was to investigate the factors involved in the biofilm development by A. nosocomialis.

METHODS

Library of random transposon mutants was constructed using the Tn5 mutagenesis. The mutant strains, in which the ability of biofilm formation was significantly impaired, were screened by gentian violet staining. The roles of BfmR and BfmS were determined by constructing a bfmR and bfmS deletion mutant and analyzing the effects of bfmR and bfmS mutation on the biofilm development and motility of A. nosocomialis.

RESULTS

We identified a biofilm-defective mutant in which a transposon insertion inactivated an open reading frame encoding the BfmR in a two-component regulatory system consisting of BfmR and BfmS. The bfmR mutant revealed a significant reduction in biofilm formation and motility compared to wild-type strain. Deficiency in the biofilm formation and motility of the bfmR mutant was restored by single copy bfmR complementation. In contrast, the bfmS mutant had no effect on biofilm formation.

CONCLUSION

A. nosocomialis has a two-component regulatory system, BfmRS. BfmR is a response regulator required for the initial attachment and maturation of biofilm during the biofilm development as well as the bacterial growth. BfmR could be a potential drug target for A. nosocomialis infection.

Predictions of Immunodominant Epitope Peptides From the AsaA Type VI Secretion System in Acinetobacter baumannii: A Computational Approach

Introduction Acinetobacter baumannii, designated as a priority pathogen by the World Health Organization (WHO), is responsible for recalcitrant infections in immunocompromised patients. The type VI secretion system (T6SS) is a class of macromolecular secretion machines, contributing to its virulence. The aim of this study is thus to predict the immune-dominant epitope peptides from the Acinetobacter T6SS-associated protein of A. baumannii (AsaA). Methods AsaA protein retrieval from the bacteria was carried out using computational platforms and the evaluation of antigenicity and allergenicity was performed. The T-cell epitopes of major histocompatibility complex class II binders were identified followed by molecular docking of the immune-dominant epitopes with human leukocyte antigen alleles using the ClusterPro server (https://cluspro.org/help.php). Additionally, the B-cell epitopes were predicted. Results Immune-informatic analysis showed immune-dominant peptides in the most favored regions with promising interactions with HLA alleles DP, DQ, DR, and toll-like receptor showing high binding capacity. Conclusion In the present investigation, epitope 1 (LILFLIGNY) was found to be a promising candidate for the synthesis of vaccines. However, it requires further experimentation for its immunological memory and response.

Seasonal meropenem resistance in Acinetobacter baumannii and influence of temperature-driven adaptation

BACKGROUND

Recognition of seasonal trends in bacterial infection and drug resistance rates may enhance diagnosis, direct therapeutic strategies, and inform preventive measures. Limited data exist on the seasonal variability of Acinetobacter baumannii. We investigated the seasonality of A. baumannii, the correlation between temperature and meropenem resistance, and the impact of temperature on this bacterium.

RESULTS

Meropenem resistance rates increased with lower temperatures, peaking in winter/colder months. Nonresistant strain detection exhibited temperature-dependent seasonality, rising in summer/warmer months and declining in winter/colder months. In contrast, resistant strains showed no seasonality. Variations in meropenem-resistant and nonresistant bacterial resilience to temperature changes were observed. Nonresistant strains displayed growth advantages at temperatures ≥ 25 °C, whereas meropenem-resistant A. baumannii with β-lactamase OXA-23 exhibited greater resistance to low-temperature (4 °C) stress. Furthermore, at 4 °C, A. baumannii upregulated carbapenem resistance-related genes (adeJ, oxa-51, and oxa-23) and increased meropenem stress tolerance.

CONCLUSIONS

Meropenem resistance rates in A. baumannii display seasonality and are negatively correlated with local temperature, with rates peaking in winter, possibly linked to the differential adaptation of resistant and nonresistant isolates to temperature fluctuations. Furthermore, due to significant resistance rate variations between quarters, compiling monthly or quarterly reports might enhance comprehension of antibiotic resistance trends. Consequently, this could assist in formulating strategies to control and prevent resistance within healthcare facilities.

Interplay of xenobiotic-degrading and antibiotic-resistant microorganisms among the microbiome found in the air, handrail, and floor of the subway station

Investigating the quality of the subway environment, especially regarding antibiotic resistance genes (ARGs) and xenobiotics, conveys ecological and health impacts. In this study, compositions and relations of microorganisms harboring ARGs and xenobiotic degradation and metabolism genes (XDGs) in the Sukhumvit subway station (MRT-SKV) in Bangkok was assessed by analyzing the taxonomic and genetic diversity of the microbiome in the air and on the surfaces of floor and handrail. The major bacteria in the MRT-SKV (including Moraxella, which was abundant in the bioaerosol and handrail samples, and Staphylococcus, which was abundant in the bioaerosol samples) were found to contain both ARGs and XDGs. The co-abundance correlation network revealed notable relationships among bacteria harboring antibiotic resistance genes (ARGs) and xenobiotic degradation genes (XDGs). Significant associations were observed between ARGs linked to glycopeptide and fluoroquinolone resistance and genes associated with benzoate, styrene, and atrazine degradation pathways, as well as between ARGs related to cephamycin, cephalosporin, and MLS resistance and XDGs associated with the cytochrome P450-dependent drug metabolism pathway. These correlations suggested that selective pressure exerted by certain xenobiotics and antibiotics can simultaneously affect both ARGs and XDGs in the environment and should favor correlations and co-survival among ARG- and XDG-containing bacteria in the environments. The correlations may occur via shared mechanisms of resistance to both xenobiotics and antibiotics. Finally, different correlation pairs were seen in different niches (air, handrail, floor) of the subway environment or different geolocations. Thus, the relationship between ARG and XDG pairs most likely depends on the unique characteristics of the niches and on the prominent types of xenobiotics and antibiotics in the subway environment. The results indicated that interactions and connections between microbial communities can impact how they function. These microorganisms can have profound effects on accumulation of xenobiotics and ARGs in the MRT-SKV.

A Comprehensive Review of Bovine Colostrum Components and Selected Aspects Regarding Their Impact on Neonatal Calf Physiology

Colostrum contains macro- and micronutrients necessary to meet the nutritional and energy requirements of the neonatal calf, bioactive components that intervene in several physiological aspects, and cells and microorganisms that modulate the calf's immune system and gut microbiome. Colostrum is sometimes mistaken as transition milk, which, although more nutritive than whole milk, has a distinct biochemical composition. Furthermore, most research about colostrum quality and colostrum management focuses on the transfer of maternal IgG to the newborn calf. The remaining components of colostrum and transition milk have not received the same attention, despite their importance to the newborn animal. In this narrative review, a large body of literature on the components of bovine colostrum was reviewed. The variability of these components was summarized, emphasizing specific components that warrant deeper exploration. In addition, the effects of each component present in colostrum and transition milk on several key physiological aspects of the newborn calf are discussed.

Characteristics of the Genetic Spread of Carbapenem-Resistant Acinetobacter baumannii in a Tertiary Greek Hospital

Acinetobacter baumannii (Ab) has increasingly been identified as a cause of hospital-acquired infections and epidemics. The rise of carbapenem-resistant Acinetobacter baumannii (CRAB) poses significant challenges in treatment. Nosocomial outbreaks linked to CRAΒ A. baumannii strains have been reported worldwide, including in Greece. This study aimed to analyze the molecular epidemiology trends of multidrug-resistant A. baumannii isolates in a tertiary hospital in Athens, Greece. A total of 43 clinical isolates of extensively drug-resistant (XDRAB), pan-drug-resistant (PDRAB), and CRAB were collected from patients suffering from blood infection, hospitalized between 2016 and 2020 at the internal medicine clinics and the ICU. A.baumannii isolates underwent testing for Ambler class B and D carbapenemases and the detection of ISAba1, and were typed, initially, using pulsed-field gel electrophoresis, and, subsequently, using sequence-based typing and multiplex PCR to determine European Clone lineages. The blaOXA-23 gene accompanied by ISAba1 was prevalent in nearly all A. baumannii isolates, except for one carrying blaOXA-58. The intrinsic blaOXA-51-like gene was found in all isolates. No Ambler class B carbapenemases (VIM, NDM) were detected. Isolates were grouped into four PF-clusters and no one-cluster spread was documented, consistent with the absence of outbreak. The study indicated that XDR/PDR-CRAB isolates predominantly produce OXA-23 carbapenemase and belong to European Clone II. Further research is needed to understand the distribution of resistant bacteria and develop effective prevention and control strategies.

Taxonomic Diversity and Functional Traits of Soil Bacterial Communities under Radioactive Contamination: A Review

Studies investigating the taxonomic diversity and structure of soil bacteria in areas with enhanced radioactive backgrounds have been ongoing for three decades. An analysis of data published from 1996 to 2024 reveals changes in the taxonomic structure of radioactively contaminated soils compared to the reference, showing that these changes are not exclusively dependent on contamination rates or pollutant compositions. High levels of radioactive exposure from external irradiation and a high radionuclide content lead to a decrease in the alpha diversity of soil bacterial communities, both in laboratory settings and environmental conditions. The effects of low or moderate exposure are not consistently pronounced or unidirectional. Functional differences among taxonomic groups that dominate in contaminated soil indicate a variety of adaptation strategies. Bacteria identified as multiple-stress tolerant; exhibiting tolerance to metals and antibiotics; producing antioxidant enzymes, low-molecular antioxidants, and radioprotectors; participating in redox reactions; and possessing thermophilic characteristics play a significant role. Changes in the taxonomic and functional structure, resulting from increased soil radionuclide content, are influenced by the combined effects of ionizing radiation, the chemical toxicity of radionuclides and co-contaminants, as well as the physical and chemical properties of the soil and the initial bacterial community composition. Currently, the quantification of the differential contributions of these factors based on the existing published studies presents a challenge.

Current treatment options for pneumonia caused by carbapenem-resistant Acinetobacter baumannii

PURPOSE OF REVIEW

The purpose of this review is to briefly summarize the challenges associated with the treatment of pneumonia caused by carbapenem-resistant Acinetobacter baumannii (CRAB), discuss its carbapenem-resistance, and review the literature supporting the current treatment paradigm and therapeutic options.

RECENT FINDINGS

In a multicenter, randomized, and controlled trial the novel β-lactam-β-lactamase inhibitor sulbactam-durlobactam was compared to colistin, both in addition to imipenem-cilastatin. The drug met the prespecified criteria for noninferiority for 28-day all-cause mortality while demonstrating higher clinical cure rates in the treatment of CRAB pneumonia. In an international, randomized, double-blind, placebo controlled trial colistin monotherapy was compared to colistin combined with meropenem. In this trial, combination therapy was not superior to monotherapy in the treatment of drug-resistant gram-negative organisms including CRAB pneumonia.

SUMMARY

CRAB pneumonia is a preeminent public health threat without an agreed upon first line treatment strategy. Historically, there have been drawbacks to available treatment modalities without a clear consensus on the first-line treatment regimen. CRAB pneumonia is a top priority for the continued development of antimicrobials, adjuvant therapies and refinement of current treatment strategies.

Genomic insights into the adaptation of Acinetobacter johnsonii RB2-047 to the heavy metal-contaminated subsurface mine environment

The subsurface mine environments characterized by high levels of toxic metals and low nutrient availability represent an extreme threat to bacterial persistence. In recent study, the genomic analysis of the Acinetobacter johnsonii strain RB2-047 isolated from the Rozália Gold Mine in Slovakia was performed. As expected, the studied isolate showed a high level of heavy metal tolerance (minimum inhibitory concentrations were 500 mg/L for copper and nickel, 1,500 mg/L for lead, and 250 mg/L for zinc). The RB2-047 strain also showed noticeable resistance to several antibiotics (ampicillin, kanamycin, chloramphenicol, tetracycline and ciprofloxacin). The genomic composition analysis demonstrated a low number of antibiotic and metal resistance coding genes, but a high occurrence of efflux transporter genes located on the bacterial chromosome. The experimental inhibition of efflux pumps resulted in decreased tolerance to Zn and Ni (but not to Cu and Pb) and to all antibiotics tested. In addition, the H33342 dye-accumulation assay confirmed the high efflux activity in the RB2-047 isolate. These findings showed the important role of efflux pumps in the adaptation of Acinetobacter johsonii strain RB2-047 to metal polluted mine environment as well as in development of multi-antibiotic resistance.

Antibiotic susceptibility patterns at the Médecins Sans Frontières (MSF) Acute Trauma Hospital in Aden, Yemen: a retrospective study from January 2018 to June 2021

Background

Antimicrobial resistance (AMR) is an urgent global health concern, especially in countries facing instability or conflicts, with compromised healthcare systems. Médecins Sans Frontières (MSF) established an acute trauma hospital in Aden, Yemen, treating mainly war-wounded civilians, and implemented an antimicrobial stewardship (AMS) programme. This study aimed to describe clinical characteristics and identify antibiotic susceptibility patterns representative of patients treated with antibiotics.

Methods

Retrospective cross-sectional study using routinely collected data from all patients treated with antibiotics in the MSF-Aden Acute Trauma hospital between January 2018 and June 2021. Routine clinical data from patients' files was entered into an AMS electronic database and microbiological data were entered into WHONET. Both databases were imported and merged in REDCap and analysed using RStudio.

Results

Three hundred and sixty-three of 481 (75%) included patients were injured by violence-related trauma. Most were men aged 19-45 years (n = 331; 68.8%). In total, 598 infections were diagnosed and treated. MDR organisms were identified in 362 (60.5%) infections in 311 (65%) patients. Skin and soft-tissue infections (SSTIs) (n = 143; 24%) were the most common, followed by osteomyelitis (n = 125; 21%) and intra-abdominal-infections (IAIs) (n = 116; 19%), and 111 (19%) secondary bloodstream infections were identified. Escherichia coli was the most frequently identified pathogen, causing IAI (n = 87; 28%) and SSTI (n = 43; 16%), while Staphylococcus aureus caused mainly osteomyelitis (n = 84; 19%). Most Gram-negatives were ESBL producers, including E. coli (n = 193; 81.4%), Klebsiella pneumoniae (n = 72; 77.4%) and Enterobacter cloacae (n = 39; 50%) while most S. aureus were methicillin resistant (n = 93; 72.6%).

Conclusions

High rates of MDR were found. This information will facilitate a comprehensive review of the empirical antibiotic treatment guidelines.

Epidemiology, resistance genomics and susceptibility of Acinetobacter species: results from the 2020 Spanish nationwide surveillance study

BackgroundAs increasing antibiotic resistance in Acinetobacter baumannii poses a global healthcare challenge, understanding its evolution is crucial for effective control strategies.AimWe aimed to evaluate the epidemiology, antimicrobial susceptibility and main resistance mechanisms of Acinetobacter spp. in Spain in 2020, and to explore temporal trends of A. baumannii.MethodsWe collected 199 single-patient Acinetobacter spp. clinical isolates in 2020 from 18 Spanish tertiary hospitals. Minimum inhibitory concentrations (MICs) for nine antimicrobials were determined. Short-read sequencing was performed for all isolates, and targeted long-read sequencing for A. baumannii. Resistance mechanisms, phylogenetics and clonality were assessed. Findings on resistance rates and infection types were compared with data from 2000 and 2010.ResultsCefiderocol and colistin exhibited the highest activity against A. baumannii, although colistin susceptibility has significantly declined over 2 decades. A. non-baumannii strains were highly susceptible to most tested antibiotics. Of the A. baumannii isolates, 47.5% (56/118) were multidrug-resistant (MDR). Phylogeny and clonal relationship analysis of A. baumannii revealed five prevalent international clones, notably IC2 (ST2, n = 52; ST745, n = 4) and IC1 (ST1, n = 14), and some episodes of clonal dissemination. Genes bla OXA-23, bla OXA-58 and bla OXA-24/40 were identified in 49 (41.5%), eight (6.8%) and one (0.8%) A. baumannii isolates, respectively. ISAba1 was found upstream of the gene (a bla OXA-51-like) in 10 isolates.ConclusionsThe emergence of OXA-23-producing ST1 and ST2, the predominant MDR lineages, shows a pivotal shift in carbapenem-resistant A. baumannii (CRAB) epidemiology in Spain. Coupled with increased colistin resistance, these changes underscore notable alterations in regional antimicrobial resistance dynamics.

Structural basis of Acinetobacter type IV pili targeting by an RNA virus

Acinetobacters pose a significant threat to human health, especially those with weakened immune systems. Type IV pili of acinetobacters play crucial roles in virulence and antibiotic resistance. Single-stranded RNA bacteriophages target the bacterial retractile pili, including type IV. Our study delves into the interaction between Acinetobacter phage AP205 and type IV pili. Using cryo-electron microscopy, we solve structures of the AP205 virion with an asymmetric dimer of maturation proteins, the native Acinetobacter type IV pili bearing a distinct post-translational pilin cleavage, and the pili-bound AP205 showing its maturation proteins adapted to pilin modifications, allowing each phage to bind to one or two pili. Leveraging these results, we develop a 20-kilodalton AP205-derived protein scaffold targeting type IV pili in situ, with potential for research and diagnostics.

Development and Evaluation of an Immunoinformatics-Based Multi-Peptide Vaccine against Acinetobacter baumannii Infection

Multi-drug-resistant (MDR) Acinetobacter baumannii is an opportunistic pathogen associated with hospital-acquired infections. Due to its environmental persistence, virulence, and limited treatment options, this organism causes both increased patient mortality and incurred healthcare costs. Thus, prophylactic vaccination could be ideal for intervention against MDR Acinetobacter infection in susceptible populations. In this study, we employed immunoinformatics to identify peptides containing both putative B- and T-cell epitopes from proteins associated with A. baumannii pathogenesis. A novel Acinetobacter Multi-Epitope Vaccine (AMEV2) was constructed using an A. baumannii thioredoxin A (TrxA) leading protein sequence followed by five identified peptide antigens. Antisera from A. baumannii infected mice demonstrated reactivity to rAMEV2, and subcutaneous immunization of mice with rAMEV2 produced high antibody titer against the construct as well as peptide components. Immunization results in increased frequency of IL-4-secreting splenocytes indicative of a Th2 response. AMEV2-immunized mice were protected against intranasal challenge with a hypervirulent strain of A. baumannii and demonstrated reduced bacterial burden at 48 h. In contrast, all mock vaccinated mice succumbed to infection within 3 days. Results presented here provide insight into the effectiveness of immunoinformatic-based vaccine design and its potential as an effective strategy to combat the rise of MDR pathogens.

Identification and Clinical Characteristics of Community-Acquired Acinetobacter baumannii in Patients Hospitalized for Moderate or Severe COVID-19 in Peru

Acinetobacter baumannii has been described as a cause of serious community-acquired infections in tropical countries. Currently, its implications when simultaneously identified with other pathogens are not yet adequately understood. A descriptive study was conducted on hospitalized patients with a diagnosis of moderate/severe SARS-CoV-2-induced pneumonia confirmed via real-time RT-PCR. Patients aged > 18 years who were admitted to a specialized COVID-19 treatment center in Peru were selected for enrollment. A. baumannii was detected via the PCR amplification of the blaOXA-51 gene obtained from nasopharyngeal swabs within 48 h of hospitalization. A total of 295 patients with COVID-19 who met the study inclusion criteria were enrolled. A. baumannii was simultaneously identified in 40/295 (13.5%) of COVID-19-hospitalized patients. Demographic data and comorbidities were comparable in both Acinetobacter-positive and -negative subgroups. However, patients identified as being infected with Acinetobacter were more likely to have received outpatient antibiotics prior to hospitalization, had a higher requirement for high-flow nasal cannula and a higher subjective incidence of fatigue, and were more likely to develop Acinetobacter-induced pneumonia during hospitalization. Conclusions: The group in which SARS-CoV-2 and A. baumannii were simultaneously identified had a higher proportion of fatigue, a higher frequency of requiring a high-flow cannula, and a higher proportion of superinfection with the same microorganism during hospitalization.

Chloramphenicol Binding Sites of Acinetobacter baumannii Chloramphenicol Acetyltransferase CatB8

Acinetobacter baumannii is a multidrug-resistant pathogen that has become one of the most challenging pathogens in global healthcare. Several antibiotic-resistant genes, including catB8, have been identified in the A. baumannii genome. CatB8 protein, one of the chloramphenicol acetyltransferases (Cats), is encoded by the catB8 gene. Cats can convert chloramphenicol (chl) to 3-acetyl-chl, leading to bacterial resistance to chl. Here, we present the high-resolution cocrystal structure of CatB8 with chl. The structure that we resolved showed that each monomer of CatB8 binds to four chl molecules, while its homologous protein only binds to one chl molecule. One of the newly discovered chl binding site overlaps with the site of another substrate, acetyl-CoA. Through structure-based biochemical analyses, we identified key residues for chl recruiting and acetylation of chl in CatB8. Our work is of significant importance for understanding the drug resistance of A. baumannii and the effectiveness of antibiotic treatment.

Hetero-antagonism of avibactam and sulbactam with cefiderocol in carbapenem-resistant Acinetobacter spp

The emergence of Gram-negative bacteria resistant to multiple antibiotics, particularly carbapenem-resistant (CR) Acinetobacter strains, poses a significant threat globally. Despite efforts to develop new antimicrobial therapies, limited progress has been made, with only two drugs-cefiderocol and sulbactam-durlobactam-showing promise for CR-Acinetobacter infections. Cefiderocol, a siderophore cephalosporin, demonstrates promising efficacy in the treatment of Gram-negative infections. However, resistance to cefiderocol has been reported in A. baumannii. Combination therapies, such as cefiderocol with avibactam or sulbactam, show reduced MICs against cefiderocol-non-susceptible strains with in vivo efficacy, although the outcomes can be complex and species-specific. In the present work, the molecular characterization of spontaneous cefiderocol-resistant variants, a CRAB strain displaying antagonism with sulbactam and an A. lwoffii strain showing antagonism with avibactam, were studied. The results reveal intriguing insights into the underlying mechanisms, including mutations affecting efflux pumps, transcriptional regulators, and iron homeostasis genes. Moreover, gene expression analysis reveals significant alterations in outer membrane proteins, iron homeostasis, and β-lactamases, suggesting adaptive responses to selective pressure. Understanding these mechanisms is crucial for optimizing treatment strategies and preventing adverse clinical outcomes. This study highlights the importance of preemptively assessing drug synergies to navigate the challenges posed by antimicrobial resistance in CR-Acinetobacter infections.

Three novel multiplex PCR assays for rapid detection of virulence, antimicrobial resistance, and toxin genes in Acinetobacter calcoaceticus-baumannii complex species

The Acinetobacter calcoaceticus-baumannii (ACB) complex is an often-overlooked group of nosocomial pathogens with a significant environmental presence. Rapid molecular screening methods for virulence, antimicrobial resistance, and toxin (VAT) genes are required to investigate the potential pathogenicity of environmental isolates. This study aimed to develop and apply novel ACB complex-specific multiplex PCR (mPCR) primers and protocols for the rapid detection of eight VAT genes. We optimized three single-tube mPCR assays using reference DNA from ACB complex and other Acinetobacter species. These assays were then applied to detect VAT genes in cultured ACB complex isolates recovered from clinical and environmental sources. Widespread detection of VAT genes in environmental isolates confirmed the validity, functionality, and applicability of these novel assays. Overall, the three newly developed ACB complex species-specific mPCR assays are rapid and simple tools that can be adopted in diagnostic and clinical lab settings. The detection of VAT genes in environmental isolates suggests that environmental niches could serve as a reservoir for potentially pathogenic ACB complex and warrants further investigation. The newly developed mPCR assays are specific, sensitive, and efficient, making them well-suited for high-throughput screening in epidemiological studies and evaluating the potential pathogenicity of ACB complex recovered from various sources.

Lactobacillus reuteri biofilms formed on porous zein/cellulose scaffolds: Synbiotics to regulate intestinal microbiota

Supplementing probiotics or indigestible carbohydrates is a usual strategy to prevent or revert unhealthy states of the gut by reshaping gut microbiota. One criterion that probiotics are efficacious is the capacity to survive in the gastrointestinal tract. Biofilm is the common growth mode of microorganisms with high tolerances toward harsh environments. Suitable scaffolds are crucial for successful biofilm culture and large-scale production of biofilm-phenotype probiotics. However, the role of scaffolds containing indigestible carbohydrates in biofilm formation has not been studied. In this study, porous zein/cellulose composite scaffolds provided nitrogen sources and carbon sources simultaneously at the solid/liquid interfaces, being beneficial to the biofilm formation of Lactobacillus reuteri. The biofilms showed 2.1-17.4 times higher tolerances in different gastrointestinal conditions. In human fecal fermentation, the biofilms combined with the zein/cellulose composite scaffolds act as the "synbiotics" positively modulating the gut microbiota and the short-chain fatty acids (SCFAs), where biofilms provide probiotics and scaffolds provide prebiotics. The "synbiotics" show a more positive regulation ability than planktonic L. reuteri, presenting potential applications in gut health interventions. These results provide an understanding of the synergistic effects of biofilm-phenotype probiotics and indigestible carbohydrates contained in the "synbiotics" in gut microbiota modulation.

Antimicrobial efficacy of eravacycline against emerging extensively drug-resistant (XDR) Acinetobacter baumannii isolates

PURPOSE

Drug-resistant Acinetobacter baumannii is an emerging threat. This study has been conducted to observe the efficacy of eravacycline along with the RND-efflux pump system.

METHODS

A cross-sectional study was done collecting 48 clinical isolates of Acinetobacter baumannii. MICs of 15 antibiotics were detected along with BMD of tigecycline and eravacycline. PCR products of drug-resistant regulatory genes were sequenced and analyzed.

RESULTS

Of the total 48 Isolates, 35 (72.91%) were XDR and 13 (27.08%) were MDR. Out of all, 60.41% of isolates were found to be susceptible to eravacycline by BMD according to both FDA and EUCAST guidelines. A 2-fold decline of MIC50/90 was observed with the use of eravacycline compared to tigecycline. RND-efflux genes like AdeC in 30 (62.5%) isolates and Regulatory gene AdeS in 29 (60.41%) isolates were detected, explaining the existing resistance mechanism.

CONCLUSIONS

XDR Acinetobacter poses an escalating threat due to its resistance to multiple antibiotics, raising serious concerns in healthcare settings. Eravacycline is an encouraging new drug for empirical use in severe infection caused due to the same. Molecular investigation and strict antimicrobial stewardship should be followed to control the emergence, and a better understanding of mechanisms of resistance to prevent the spread of drug-resistant isolates.

Characterization of two bacteriophages specific to Acinetobacter baumannii and their effects on catheters biofilm

Multidrug-resistant strains of Acinetobacter baumannii cause major nosocomial infections. Bacteriophages that are specific to the bacterial species and destroy bacteria can be effectively used for treatment. In this study, we characterized lytic bacteriophages specific to A. baumannii strains. We isolated lytic bacteriophages from environmental water samples and then investigated their morphology, host range, growth characteristics, stability, genome analysis, and biofilm destruction on the catheter surface. Our results showed that the efficacy of the phages varied between 32% and 78%, tested on 78 isolates of A. baumannii; 80 phages were isolated, and two lytic bacteriophages, vB_AbaP_HB01 (henceforth called C2 phage) and vB_AbaM_HB02 (henceforth called K3 phage), were selected for characterization. Electron microscopy scans revealed that the C2 and K3 phages were members of the Podoviridae and Myoviridae families, respectively. Whole-genome sequencing revealed that the sequence of the C2 phage is available in the NCBI database (accession number: OP917929.1), and it was found sequence identity with Acinetobacter phage AB1 18%, the K3 phage DNA sequence is closely related to Acinetobacter phage vB_AbaM_phiAbaA1 (94% similarity). The cocktail of C2 and K3 phages demonstrated a promising decrease in the bacterial cell counts of the biofilm after 4 h. Under a scanning electron microscope, the cocktail treatment destructed the biofilm on the catheter. We propose that the phage cocktail could be a strong alternative to antibiotics to control the A. baumannii biofilm in catheter infections.

Colistin resistance in carbapenem non-susceptible Acinetobacter baumanii in a tertiary care hospital in India: clinical characteristics, antibiotic susceptibility and molecular characterization

INTRODUCTION

Acinetobacter baumanii (AB) is a bacterium of concern in the hospital setup due to its ability to thrive in unfavorable conditions and the rapid emergence of antibiotic resistance. Carbapenem resistance in this organism is disheartening, further clouded by the emergence of colistin resistance.

AIM

The present prospective study aims to note the epidemiology, molecular profile, and clinical outcome of patients with colistin resistance AB infections in a multispecialty tertiary care setup in Odisha, Eastern India.

METHODS

All AB strains received from March 2021 to February 2022, identified by Vitek2 (Biomerieux) and confirmed by oxa-51 genes, were included. Carbapenem and colistin resistance were identified as per CLSI guidelines. Known mutations for blaOXA-23-like, blaIMP, blaVIM, blaKP, lpxA, lpxC, pmrA, pmrB, and plasmid mediated mcr (mcr1-5) were screened by conventional PCR techniques. The clinical outcome was noted retrospectively from case sheets. Data was entered in MS Excel and tabulated using SPSS software.

RESULTS

In the study period, 350 AB were obtained, of which 317(90.5%) were carbapenem resistant (CRAB). Among the CRAB isolates, 19 (5.9%) were colistin resistant (ABCoR). The most valuable antibiotics in the study were tigecycline (65.4% in ABCoI; 31.6% in ABCoR) and minocycline (44.3% in CI; 36.8% in CR). There was a significant difference in mortality among ABCoI and ABCoR infections. bla OXA was the predominant carbapenem resistance genotype, while pmrA was the predominant colistin resistant genotype. There were no plasmid mediated mcr genes detected in the present study.

Risk Factors Associated with Mortality in Acinetobacter baumannii Infections: Results of a Prospective Cohort Study in a Tertiary Public Hospital in Guayaquil, Ecuador

Antibiotic overuse and the resulting antimicrobial resistance pose significant global public health challenges, providing an avenue for opportunistic pathogens like Acinetobacter baumannii to thrive. This study will report the trends of Acinetobacter baumannii antimicrobial resistance patterns at the Hospital Teodoro Maldonado Carbo, Ecuador. An observational, analytical, longitudinal, and prospective study was conducted involving patients diagnosed with hospital-acquired infections. Antimicrobial susceptibility testing was performed, followed by molecular analysis of carbapenemase genes in Acinetobacter baumannii isolates. We included 180 patients aged from 16 to 93 years. The hospital mortality rate was 63/180 (35%). Invasive mechanical ventilation (IMV) was indicated in 91/180 patients (50.4%). The overall survival (OS) rate in patients on IMV was 49.5% (45/91), with a median survival of 65 days. The OS rate in patients not on IMV was 80.9% (72/89), with a median survival of 106 days (HR 2.094; 95% CI 1.174-3.737; p = 0.012). From multivariate analysis, we conclude that ventilator-associated pneumonia is the most related factor to OS.

Antibiotic resistance: a global crisis, problems and solutions

Healthy state is priority in today's world which can be achieved using effective medicines. But due to overuse and misuse of antibiotics, a menace of resistance has increased in pathogenic microbes. World Health Organization (WHO) has announced ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) as the top priority pathogens as these have developed resistance against certain antibiotics. To combat such a global issue, it is utmost important to identify novel therapeutic strategies/agents as an alternate to such antibiotics. To name certain antibiotic adjuvants including: inhibitors of beta-lactamase, efflux pumps and permeabilizers for outer membrane can potentially solve the antibiotic resistance problems. In this regard, inhibitors of lytic domain of lytic transglycosylases provide a novel way to not only act as an alternate to antibiotics but also capable of restoring the efficiency of previously resistant antibiotics. Further, use of bacteriophages is another promising strategy to deal with antibiotic resistant pathogens. Taking in consideration the alternatives of antibiotics, a green synthesis nanoparticle-based therapy exemplifies a good option to combat microbial resistance. As horizontal gene transfer (HGT) in bacteria facilitates the evolution of new resistance strains, therefore identifying the mechanism of resistance and development of inhibitors against it can be a novel approach to combat such problems. In our perspective, host-directed therapy (HDT) represents another promising strategy in combating antimicrobial resistance (AMR). This approach involves targeting specific factors within host cells that pathogens rely on for their survival, either through replication or persistence. As many new drugs are under clinical trials it is advisable that more clinical data and antimicrobial stewardship programs should be conducted to fully assess the clinical efficacy and safety of new therapeutic agents.

Genomic analysis of diverse environmental Acinetobacter isolates identifies plasmids, antibiotic resistance genes, and capsular polysaccharides shared with clinical strains

Acinetobacter baumannii, an important pathogen known for its widespread antibiotic resistance, has been the focus of extensive research within its genus, primarily involving clinical isolates. Consequently, data on environmental A. baumannii and other Acinetobacter species remain limited. Here, we utilized Illumina and Nanopore sequencing to analyze the genomes of 10 Acinetobacter isolates representing 6 different species sourced from aquatic environments in South Australia. All 10 isolates were phylogenetically distinct compared to clinical and other non-clinical Acinetobacter strains, often tens of thousands of single-nucleotide polymorphisms from their nearest neighbors. Despite the genetic divergence, we identified pdif modules (sections of mobilized DNA) carrying clinically important antimicrobial resistance genes in species other than A. baumannii, including carbapenemase oxa58, tetracycline resistance gene tet(39), and macrolide resistance genes msr(E)-mph(E). These pdif modules were located on plasmids with high sequence identity to those circulating in globally distributed A. baumannii ST1 and ST2 clones. The environmental A. baumannii isolate characterized here (SAAb472; ST350) did not possess any native plasmids; however, it could capture two clinically important plasmids (pRAY and pACICU2) with high transfer frequencies. Furthermore, A. baumannii SAAb472 possessed virulence genes and a capsular polysaccharide type analogous to clinical strains. Our findings highlight the potential for environmental Acinetobacter species to acquire and disseminate clinically important antimicrobial resistance genes, underscoring the need for further research into the ecology and evolution of this important genus.IMPORTANCEAntimicrobial resistance (AMR) is a global threat to human, animal, and environmental health. Studying AMR in environmental bacteria is crucial to understand the emergence and dissemination of resistance genes and pathogens, and to identify potential reservoirs and transmission routes. This study provides novel insights into the genomic diversity and AMR potential of environmental Acinetobacter species. By comparing the genomes of aquatic Acinetobacter isolates with clinical and non-clinical strains, we revealed that they are highly divergent yet carry pdif modules that encode resistance to antibiotics commonly used in clinical settings. We also demonstrated that an environmental A. baumannii isolate can acquire clinically relevant plasmids and carries virulence factors similar to those of hospital-associated strains. These findings suggest that environmental Acinetobacter species may serve as reservoirs and vectors of clinically important genes. Consequently, further research is warranted to comprehensively understand the ecology and evolution of this genus.

Stachyose in combination with L. rhamnosus GG ameliorates acute hypobaric hypoxia-induced intestinal barrier dysfunction through alleviating inflammatory response and oxidative stress

High altitude is closely related to intestinal mucosal damage and intestinal microbiota imbalance, and there is currently no effective prevention and treatment measures. In this study, the effects of stachyose (STA), L. rhamnosus GG (LGG) and their combination on inflammatory response, oxidatve stress and intestinal barrier function in mice exposed to acute hypobaric hypoxia were investigated. Our results indicated the combination of STA and LGG could more effectively regulate intestinal microbiota disorders caused by hypobaric hypoxia than STA or LGG alone. When mice were administered with STA + LGG, the content of short chain fatty acids (SCFAs) especially butyric acid significantly increased, which helped intestinal cells to form tight connections, improve the level of anti-inflammatory cytokine (TGF-β) and antioxidant enzymes (SOD, CAT, GSH-Px), and decrease the expression of pro-inlammatory cytokines and hypoxia-inducing factors (IFN-γ, IL-1β, IL-6, TNF-α and HIF-1α), thereby enhance the strong intestinal barrier function. Furthermore, the synbiotics significantly reduced the ratio of Firmicutes to Bacteroidetes, while significantly increased the relative abundance of Rikenella, Bacteroides, Odoribacter, Ruminiclostridium_5 and Gordonibacter, which were correlated with production of SCFAs and anti-inflammatory role. Correlation analysis showed that the protective effect of synbiotics on intestinal barrier function was associated with its anti-inflammatory activity and antioxidant capacity. It provided a strong foundation for further research on the role of STA and LGG in maintaining normal intestinal function at high altitude. Our study has identified and demonstrated a new synbiotic that may be one of the ideal intervention measures for preventing and treating intestinal dysfunction at high altitude.

Clinical Outcomes and Bacterial Characteristics of Carbapenem-resistant Acinetobacter baumannii Among Patients From Different Global Regions

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAb) is 1 of the most problematic antimicrobial-resistant bacteria. We sought to elucidate the international epidemiology and clinical impact of CRAb.

METHODS

In a prospective observational cohort study, 842 hospitalized patients with a clinical CRAb culture were enrolled at 46 hospitals in five global regions between 2017 and 2019. The primary outcome was all-cause mortality at 30 days from the index culture. The strains underwent whole-genome analysis.

RESULTS

Of 842 cases, 536 (64%) represented infection. By 30 days, 128 (24%) of the infected patients died, ranging from 1 (6%) of 18 in Australia-Singapore to 54 (25%) of 216 in the United States and 24 (49%) of 49 in South-Central America, whereas 42 (14%) of non-infected patients died. Bacteremia was associated with a higher risk of death compared with other types of infection (40 [42%] of 96 vs 88 [20%] of 440). In a multivariable logistic regression analysis, bloodstream infection and higher age-adjusted Charlson comorbidity index were independently associated with 30-day mortality. Clonal group 2 (CG2) strains predominated except in South-Central America, ranging from 216 (59%) of 369 in the United States to 282 (97%) of 291 in China. Acquired carbapenemase genes were carried by 769 (91%) of the 842 isolates. CG2 strains were significantly associated with higher levels of meropenem resistance, yet non-CG2 cases were over-represented among the deaths compared with CG2 cases.

CONCLUSIONS

CRAb infection types and clinical outcomes differed significantly across regions. Although CG2 strains remained predominant, non-CG2 strains were associated with higher mortality. Clinical Trials Registration. NCT03646227.

Treatment and Management of Acinetobacter Pneumonia: Lessons Learned from Recent World Event

Acinetobacter pneumonia is a significant healthcare-associated infection that poses a considerable challenge to clinicians due to its multidrug-resistant nature. Recent world events, such as the COVID-19 pandemic, have highlighted the need for effective treatment and management strategies for Acinetobacter pneumonia. In this review, we discuss lessons learned from recent world events, particularly the COVID-19 pandemic, in the context of the treatment and management of Acinetobacter pneumonia. We performed an extensive literature review to uncover studies and information pertinent to the topic. The COVID-19 pandemic underscored the importance of infection control measures in healthcare settings, including proper hand hygiene, isolation protocols, and personal protective equipment use, to prevent the spread of multidrug-resistant pathogens like Acinetobacter. Additionally, the pandemic highlighted the crucial role of antimicrobial stewardship programs in optimizing antibiotic use and curbing the emergence of resistance. Advances in diagnostic techniques, such as rapid molecular testing, have also proven valuable in identifying Acinetobacter infections promptly. Furthermore, due to the limited availability of antibiotics for treating infections caused A. baumannii, alternative strategies are needed like the use of antimicrobial peptides, bacteriophages and their enzymes, nanoparticles, photodynamic and chelate therapy. Recent world events, particularly the COVID-19 pandemic, have provided valuable insights into the treatment and management of Acinetobacter pneumonia. These lessons emphasize the significance of infection control, antimicrobial stewardship, and early diagnostics in combating this challenging infection.

The role of type VI secretion system genes in antibiotic resistance and virulence in Acinetobacter baumannii clinical isolates

Introduction

The type VI secretion system (T6SS) is a crucial virulence factor in the nosocomial pathogen Acinetobacter baumannii. However, its association with drug resistance is less well known. Notably, the roles that different T6SS components play in the process of antimicrobial resistance, as well as in virulence, have not been systematically revealed.

Methods

The importance of three representative T6SS core genes involved in the drug resistance and virulence of A. baumannii, namely, tssB, tssD (hcp), and tssM was elucidated.

Results

A higher ratio of the three core genes was detected in drug-resistant strains than in susceptible strains among our 114 A. baumannii clinical isolates. Upon deletion of tssB in AB795639, increased antimicrobial resistance to cefuroxime and ceftriaxone was observed, alongside reduced resistance to gentamicin. The ΔtssD mutant showed decreased resistance to ciprofloxacin, norfloxacin, ofloxacin, tetracycline, and doxycycline, but increased resistance to tobramycin and streptomycin. The tssM-lacking mutant showed an increased sensitivity to ofloxacin, polymyxin B, and furazolidone. In addition, a significant reduction in biofilm formation was observed only with the ΔtssM mutant. Moreover, the ΔtssM strain, followed by the ΔtssD mutant, showed decreased survival in human serum, with attenuated competition with Escherichia coli and impaired lethality in Galleria mellonella.

Discussion

The above results suggest that T6SS plays an important role, participating in the antibiotic resistance of A. baumannii, especially in terms of intrinsic resistance. Meanwhile, tssM and tssD contribute to bacterial virulence to a greater degree, with tssM being associated with greater importance.

Genomic investigation unveils colistin resistance mechanism in carbapenem-resistant Acinetobacter baumannii clinical isolates

Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrABC two-component system and overexpression of eptA gene due to upstream insertion of ISAba1 have been shown to play a major role. Thus, the aim of our study is to characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 207 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrABC genes were characterized by whole-genome shotgun sequencing. Twenty-eight complete genomes were further characterized by hybrid assembly approach to study insertional inactivation of lpx genes and the association of ISAba1-eptA. Several single point mutations (SNPs), like M12I in pmrA, A138T and A444V in pmrB, and E117K in lpxD, were identified. We are the first to report two novel SNPs (T7I and V383I) in the pmrC gene. Among the five colistin-resistant A. baumannii isolates where complete genome was available, the analysis showed that three of the five isolates had ISAba1 insertion upstream of eptA. No mcr genes were identified among the isolates. We mapped the SNPs on the respective protein structures to understand the effect on the protein activity. We found that majority of the SNPs had little effect on the putative protein function; however, some SNPs might destabilize the local structure. Our study highlights the diversity of colistin resistance mechanisms occurring in A. baumannii, and ISAba1-driven eptA overexpression is responsible for colistin resistance among the Indian isolates.IMPORTANCEAcinetobacter baumannii is a Gram-negative, emerging and opportunistic bacterial pathogen that is often associated with a wide range of nosocomial infections. The treatment of these infections is hindered by increase in the occurrence of A. baumannii strains that are resistant to most of the existing antibiotics. The current drug of choice to treat the infection caused by A. baumannii is colistin, but unfortunately, the bacteria started to show resistance to the last-resort antibiotic. The loss of lipopolysaccharides and mutations in lipid A biosynthesis genes are the main reasons for the colistin resistance. The present study characterized 207 A. baumannii clinical isolates and constructed complete genomes of 28 isolates to recognize the mechanisms of colistin resistance. We showed the mutations in the colistin-resistant variants within genes essential for lipid A biosynthesis and that cause these isolates to lose the ability to produce lipopolysaccharides.

Genomic analysis of extensively drug-resistant Acinetobacter baumannii harbouring a conjugative plasmid containing aminoglycoside resistance transposon TnaphA6

The occurrence of multidrug-resistant Acinetobacter baumannii (MDRA) has increased rapidly and is associated with severe nosocomial infections. MDRA has emerged in the hospital setting and has evolved into extensively drug-resistant A. baumannii (XDRA). A clinical XDRA isolate obtained from a hospitalised patient in 2016 was evaluated for antibiotic susceptibility and whole-genome sequence. The XDRA isolate was resistant to β-lactams, including broad-spectrum cephalosporins and carbapenems, and to aminoglycosides, fosfomycin, fluoroquinolones, tetracyclines, tigecycline, and trimethoprim-sulfamethoxazole. The isolate harboured abaF, ant(3″)-II-c, aph(3″)-Ib, aph(6)-Id, armA, blaADC-73, blaTEM-1, blaOXA-66, blaOXA-23, mphE, msrE and tet(B). Quinolone resistance was associated with mutations gyrA S81L and parC S84L. Tigecycline resistance was associated with a mutation in adeS. The isolate belonged to Oxford and Pasteur scheme sequence type 1050 and 2, respectively, and harboured a conjugative plasmid containing the aminoglycoside resistance transposon TnaphA6. Our study demonstrates that the isolate is closely related to a recent MDRA identified in Australia and the USA, in which a similar conjugative plasmid is not observed. Although the MDRA in Australia caused an outbreak, our hospital's surveillance protocol managed to prevent a further outbreak. Our finding suggests that this XDRA isolate is of concern in hospital and community care settings. The gpi allele could be a marker for discriminating this isolate from clonal complex 92 isolates.

Acinetobacter baumannii infection in intensive care unit: analysis of distribution and drug resistance

BACKGROUND

The isolation rate and drug resistance rate of Acinetobacter baumannii (A.baumannii) have increased over the years, which has become one of the main causes of infection and death in intensive care unit (ICU) patients. Analysis of the distribution characteristics, drug resistance and influencing factors of A.baumannii in ICU could provide basis and reference for the infection prevention and clinical treatment.

METHODS AND RESULTS

In this study, patients diagnosed with A.baumannii infection in ICU from January 2020 to December 2021 were selected. Samples of patients were collected for bacterial culture, drug sensitivity test analysis and drug resistant gene detection of A.baumannii. A total of 197 strains of A.baumannii were cultured in 2021, which was 18 strains more than in 2020. The specimens were mainly from lower respiratory tract secretions, and the isolated strains were multi-drug resistant. The resistance of isolates to tobramycin, gentamicin, and trimethoprim-sulfamethoxazole in 2021 showed a significant increase compared to 2020, while there were no significant differences observed in other resistance changes. The prevalence of multi-drug resistant A.baumannii in ICU remains high. Among them, all imipenem-resistant A.baumannii strains carried OXA-23 gene.

CONCLUSION

Clinical treatment should use antibiotics reasonably based on the characteristics of bacterial resistance, and strengthen the prevention and control of hospital infection, pay more attention to the disinfection and isolation to reduce the risk of cross infection.

Epidemiology and antimicrobial resistance trends of Acinetobacter species in the United Arab Emirates: a retrospective analysis of 12 years of national AMR surveillance data

Introduction

Acinetobacter spp., in particular A. baumannii, are opportunistic pathogens linked to nosocomial pneumonia (particularly ventilator-associated pneumonia), central-line catheter-associated blood stream infections, meningitis, urinary tract infections, surgical-site infections, and other types of wound infections. A. baumannii is able to acquire or upregulate various resistance determinants, making it frequently multidrug-resistant, and contributing to increased mortality and morbidity. Data on the epidemiology, levels, and trends of antimicrobial resistance of Acinetobacter spp. in clinical settings is scarce in the Gulf Cooperation Council (GCC) and Middle East and North Africa (MENA) regions.

Methods

A retrospective 12-year analysis of 17,564 non-duplicate diagnostic Acinetobacter spp. isolates from the United Arab Emirates (UAE) was conducted. Data was generated at 317 surveillance sites by routine patient care during 2010-2021, collected by trained personnel and reported by participating surveillance sites to the UAE National AMR Surveillance program. Data analysis was conducted with WHONET.

Results

Species belonging to the A. calcoaceticus-baumannii complex were mostly reported (86.7%). They were most commonly isolated from urine (32.9%), sputum (29.0%), and soft tissue (25.1%). Resistance trends to antibiotics from different classes during the surveillance period showed a decreasing trend. Specifically, there was a significant decrease in resistance to imipenem, meropenem, and amikacin. Resistance was lowest among Acinetobacter species to both colistin and tigecycline. The percentages of multidrug-resistant (MDR) and possibly extensively drug-resistant (XDR) isolates was reduced by almost half between the beginning of the study in 2010 and its culmination in 2021. Carbapenem-resistant Acinetobacter spp. (CRAB) was associated with a higher mortality (RR: 5.7), a higher admission to ICU (RR 3.3), and an increased length of stay (LOS; 13 excess inpatient days per CRAB case), as compared to Carbapenem-susceptible Acinetobacter spp.

Conclusion

Carbapenem-resistant Acinetobacter spp. are associated with poorer clinical outcomes, and higher associated costs, as compared to carbapenem-susceptible Acinetobacter spp. A decreasing trend of MDR Acinetobacter spp., as well as resistance to all antibiotic classes under surveillance was observed during 2010 to 2021. Further studies are needed to explore the reasons and underlying factors leading to this remarkable decrease of resistance over time.

Pandrug-resistant Acinetobacter baumannii from different clones and regions in Mexico have a similar plasmid carrying the blaOXA-72 gene

Background

Multidrug-resistant Acinetobacter baumannii is a common hospital-acquired pathogen. The increase in antibiotic resistance is commonly due to the acquisition of mobile genetic elements carrying antibiotic resistance genes. To comprehend this, we analyzed the resistome and virulome of Mexican A. baumannii multidrug-resistant isolates.

Methods

Six clinical strains of A. baumannii from three Mexican hospitals were sequenced using the Illumina platform, the genomes were assembled with SPAdes and annotated with Prokka. Plasmid SPAdes and MobRecon were used to identify the potential plasmid sequences. Sequence Type (ST) assignation under the MLST Oxford scheme was performed using the PubMLST database. Homologous gene search for known virulent factors was performed using the virulence factor database VFDB and an in silico prediction of the resistome was conducted via the ResFinder databases.

Results

The six strains studied belong to different STs and clonal complexes (CC): two strains were ST208 and one was ST369; these two STs belong to the same lineage CC92, which is part of the international clone (IC) 2. Another two strains were ST758 and one was ST1054, both STs belonging to the same lineage CC636, which is within IC5. The resistome analysis of the six strains identified between 7 to 14 antibiotic resistance genes to different families of drugs, including beta-lactams, aminoglycosides, fluoroquinolones and carbapenems. We detected between 1 to 4 plasmids per strain with sizes from 1,800 bp to 111,044 bp. Two strains from hospitals in Mexico City and Guadalajara had a plasmid each of 10,012 bp pAba78r and pAba79f, respectively, which contained the bla OXA-72 gene. The structure of this plasmid showed the same 13 genes in both strains, but 4 of them were inverted in one of the strains. Finally, the six strains contain 49 identical virulence genes related to immune response evasion, quorum-sensing, and secretion systems, among others.

Conclusion

Resistance to carbapenems due to pAba78r and pAba79f plasmids in Aba pandrug-resistant strains from different geographic areas of Mexico and different clones was detected. Our results provide further evidence that plasmids are highly relevant for the horizontal transfer of antibiotic resistance genes between different clones of A. baumannii.

Virulence Factors and Pathogenicity Mechanisms of Acinetobacter baumannii in Respiratory Infectious Diseases

Acinetobacter baumannii (A. baumannii) has become a notorious pathogen causing nosocomial and community-acquired infections, especially ventilator-associated pneumonia. This opportunistic pathogen is found to possess powerful genomic plasticity and numerous virulence factors that facilitate its success in the infectious process. Although the interactions between A. baumannii and the pulmonary epitheliums have been extensively studied, a complete and specific description of its overall pathogenic process is lacking. In this review, we summarize the current knowledge of the antibiotic resistance and virulence factors of A. baumannii, specifically focusing on the pathogenic mechanisms of this detrimental pathogen in respiratory infectious diseases. An expansion of the knowledge regarding A. baumannii pathogenesis will contribute to the development of effective therapies based on immunopathology or intracellular signaling pathways to eliminate this harmful pathogen during infections.

Cefiderocol and Sulbactam-Durlobactam against Carbapenem-Resistant Acinetobacter baumannii

Infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) remain a clinical challenge due to limited treatment options. Recently, cefiderocol, a novel siderophore cephalosporin, and sulbactam-durlobactam, a bactericidal β-lactam-β-lactamase inhibitor combination, have been approved by the Food and Drug Administration for the treatment of A. baumannii infections. In this review, we discuss the mechanisms of action of and resistance to cefiderocol and sulbactam-durlobactam, the antimicrobial susceptibility of A. baumannii isolates to these drugs, as well as the clinical effectiveness of cefiderocol and sulbactam/durlobactam-based regimens against CRAB. Overall, cefiderocol and sulbactam-durlobactam show an excellent antimicrobial activity against CRAB. The review of clinical studies evaluating the efficacy of cefiderocol therapy against CRAB indicates it is non-inferior to colistin/other treatments for CRAB infections, with a better safety profile. Combination treatment is not associated with improved outcomes compared to monotherapy. Higher mortality rates are often associated with prior patient comorbidities and the severity of the underlying infection. Regarding sulbactam-durlobactam, current data from the pivotal clinical trial and case reports suggest this antibiotic combination could be a valuable option in critically ill patients affected by CRAB infections, in particular where no other antibiotic appears to be effective.

Trends in the susceptibility of U.S. Acinetobacter baumannii-calcoaceticus species complex and Stenotrophomonas maltophilia isolates to minocycline, 2014-2021

IMPORTANCE

Acinetobacter baumannii-calcoaceticus species complex and Stenotrophomonas maltophilia are opportunistic, non-fermentative Gram-negative organisms that can cause serious hospital-acquired infections in immunocompromised patients. These pathogens are inherently resistant to several common drug classes and often acquire other resistance mechanisms, making them difficult to treat. In this study, we analyzed the trends of susceptibility of over 2,500 U.S. bacterial isolates collected from hospitalized patients over an 8-year period to minocycline, which is used to treat infections caused by these pathogens. These in vitro data suggest that minocycline is a useful treatment option for infections caused by Acinetobacter baumannii-calcoaceticus species complex or Stenotrophomonas maltophilia.

The microbiology and pathogenesis of nonfermenting Gram-negative infections

PURPOSE OF REVIEW

This review provides an overview of most recent evidence about pathogenesis traits and virulence factors contributing to successful colonization or infection by P. aeruginosa , A. baumannii , S. maltophilia and B. cepacia complex, among the most clinically relevant nonfermenting Gram-negative bacteria (NFGNB).

RECENT FINDINGS

The growing clinical importance of NFGNB as important opportunistic pathogens causing difficult-to-treat infections in a fragile patients' population in stressed by numerous studies. Identification of novel virulence factors and deciphering of their mechanisms of action have greatly furthered our understanding of NFGNB pathogenesis, revealing that each pathogen-specific armamentarium of virulence factors (adhesins, motility, capsule, biofilm, lipopolysaccharide, exotoxins, exoenzymes, secretion systems, siderophores) can be likely responsible for the difference in the pathophysiology even in the context of a similar infection site. Emerging evidence of the immunomodulatory effect of some virulence factors is also acknowledged.

SUMMARY

NFGNB continue to be a serious global problem as cause of life-threatening opportunistic infections, owing to a highly heterogeneous content of virulence factors and their extensive number of intrinsic resistance mechanisms. Further efforts in development of novel effective antimicrobials and of alternative strategies targeting key virulence factors are warranted.

Metagenomic next-generation sequencing of bronchoalveolar lavage fluid in non-severe and severe pneumonia patients

Metagenomic next-generation sequencing (mNGS) is widely used as a more promising technology than conventional tests. However, its clinical utility in the context of bronchoalveolar lavage fluid (BALF) samples for discriminating between non-severe and severe pneumonia is not well established. Thus, this study aimed to investigate the diagnostic performance of mNGS on BALF samples from 100 individuals suspected of pneumonia, and compared it with conventional microbiological tests (CMT) of BALF samples and the final clinical diagnosis. Twenty-seven cases of non-severe pneumonia and 73 cases of severe pneumonia patients were finally clinically diagnosed. Among 100 cases, diagnostic performance of mNGS and culture showed a significant difference; 65 cases had the same sample types, of which 25 cases were diagnosed as positive by mNGS only (38.46%) and 1 was diagnosed as positive by culture only (1.54%). Moreover, 24 cases were diagnosed positive in both mNGS and culture (36.92%) and 15 cases tested negative in both mNGS and culture (23.08%). Among 35 cases, 28 out of 35 cases were diagnosed as positive by mNGS, while only 4 out of 35 cases were diagnosed as positive by the indirect immunofluorescence method (IIFT). In addition, the positive rate of mNGS was higher than that of culture in cases regardless of prior antibiotic exposure. Mixed pathogens were found to be significantly more prevalent in severe pneumonia patients than in non-severe pneumonia patients. Importantly, among 38 cases who were diagnosed solely by mNGS, 25 patients experienced an improved outcome after physicians changed the therapy according to the mNGS results. In conclusion, the results showed that mNGS of BALF represents a potentially effective tool for detection of mixed pathogens in severe pneumonia.

Antibacterial and antibiofilm activity of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H pyrazoles and thiazoles in multidrug-resistant pathogens

To find novel antibiotic drugs, six 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H derivatives named 1b, 1d (pyrazoles), 2a, 2b, 2c, and 2d (thiazoles) were evaluated in silico and in vitro. The in silico analyses were based on ADME pharmacokinetic parameters (absorption, distribution, metabolism, and excretion). The in vitro antibacterial activity was evaluated in Gram-positive and Gram-negative species (Staphylococcus aureus ATCC® 25904, Staphylococcus epidermidis ATCC® 35984, Klebsiella pneumoniae ATCC® 700603, and Acinetobacter baumannii ATCC® 19606), by determination of minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), kinetics curve, and antibiofilm assays. As results, the azoles have activity against the Gram-negative species K. pneumoniae ATCC® 700603 and A. baumannii ATCC® 19606. No antibacterial activity was observed for the Gram-positive bacteria evaluated. Thus, the azoles were evaluated against clinical isolates of K. pneumoniae carbapenemase (KPC) and A. baumannii multidrug-resistant (Ab-MDR). All azoles have antibacterial activity against Ab-MDR isolates (Gram-negative) with MIC values between 512 μg/mL and 1,024 μg/mL. Against KPC isolates the azoles 1b, 1d, and 2d present antibacterial activity (MIC = 1,024 μg/mL). In the kinetics curve assay, the 1b and 1d pyrazoles reduced significantly viable cells of Ab-MDR isolates and additionally inhibited 86.6 to 95.8% of the biofilm formation. The in silico results indicate high possibility to permeate the blood-brain barrier (2b) and was predict human gastrointestinal absorption (all evaluated azoles). Considering that the research and development of new antibiotics is a priority for drug-resistant pathogens, our study revealed the antibacterial and antibiofilm activity of novel azoles against K. pneumoniae and A. baumannii pathogens.