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.

Ineffectiveness of colistin monotherapy in treating carbapenem-resistant Acinetobacter baumannii Pneumonia: A retrospective single-center cohort study.

BACKGROUND: Acinetobacter baumannii, a common carbapenem-resistant gram-negative bacillus, usually causes nosocomial infections. Colistin has been used for carbapenem-resistant A. baumannii (CRAB) infections; however, only a few studies have evaluated colistin as a treatment option compared to appropriate controls. We investigated the effectiveness of colistin monotherapy in treating CRAB pneumonia compared to those treated without an active drug. METHODS: Adult patients (≥ 18 years) with CRAB isolated from respiratory specimens were screened from September 2017 to August 2022. Only patients with pneumonia treated with colistin monotherapy (colistin group) were included and compared to those without any active antibiotics (no active antibiotics [NAA] group). The primary and secondary outcomes were 30-day all-cause mortality and acute kidney injury within 30 days. The inverse probability of the treatment-weighted Cox proportional hazard model was used to compare mortality between groups. RESULTS: Among the 826 adult patients with CRAB in their respiratory specimens, 45 and 123 patients were included in the colistin and NAA groups, respectively. Most of the CRAB pneumonia (91.1%) cases were hospital-acquired pneumonia. The 30-day all-cause mortality rates in the colistin and NAA groups were 58.3% and 56.1%, respectively, and no difference was observed after adjustments (adjusted hazard ratio, 0.74; 95% CI, 0.47-1.17). The incidence of acute kidney injury was higher in the colistin group (65.3%) compared to the NAA group (39.0%) (P = 0.143). CONCLUSIONS: Colistin monotherapy did not significantly improve treatment outcomes for CRAB pneumonia. The development and evaluation of new antimicrobials for CRAB pneumonia should be advocated in clinical practice.

Tracing clinically-relevant antimicrobial resistances in Acinetobacter baumannii-calcoaceticus complex across diverse environments: A study spanning clinical, livestock, and wastewater treatment settings.

Acinetobacter baumannii has become a prominent nosocomial pathogen, primarily owing to its remarkable ability to rapidly acquire resistance to a wide range of antimicrobial agents and its ability to persist in diverse environments. However, there is a lack of data on the molecular epidemiology and its potential implications for public health of A. baumannii strains exhibiting clinically significant resistances that originate from non-clinical environments. Therefore, the genetic characteristics and resistance mechanisms of 80 A. baumannii-calcoaceticus (ABC) complex isolates, sourced from environments associated with poultry and pig production, municipal wastewater treatment plants (WWTPs), and clinical settings, were investigated. In total, our study classified 54 isolates into 29 previously described sequence types (STs), while 26 isolates exhibited as-yet-unassigned STs. We identified a broad range of A. baumannii STs originating from poultry and pig production environments (e.g., ST10, ST238, ST240, ST267, ST345, ST370, ST372, ST1112 according to Pasteur scheme). These STs have also been documented in clinical settings worldwide, highlighting their clinical significance. These findings also raise concerns about the potential zoonotic transmission of certain STs associated with livestock environments. Furthermore, we observed that clinical isolates exhibited the highest diversity of antimicrobial resistance genes (ARGs). In contrast to non-clinical isolates, clinical isolates typically carried a significantly higher number of ARGs, ranging from 10 to 15. They were also the exclusive carriers of biocide resistance genes and acquired carbapenemases (blaOXA-23, blaOXA-58, blaOXA-72, blaGIM-1, blaNDM-1). Additionally, we observed that clinical strains displayed an increased capacity for carrying plasmids and undergoing genetic transformation. This heightened capability could be linked to the intense selective pressures commonly found within clinical settings. Our study provides comprehensive insights into essential aspects of ABC isolates originating from livestock-associated environments and clinical settings. We explored their resistance mechanisms and potential implications for public health, providing valuable knowledge for addressing these critical issues.

Dynamics of blaOXA-23 gene transmission in Acinetobacter spp. from contaminated veterinary environmental surfaces: an emerging One Health threat?

BACKGROUND: Carbapenem-resistant Acinetobacter baumannii is a common pathogen associated with healthcare-acquired infections, and robust infection prevention and control protocols exist in human healthcare settings. In contrast, infection prevention and control (IPC) standards are limited in veterinary medicine, necessitating further investigation. AIM: Examine the possible transmission of carbapenem-resistant Acinetobacter spp. in a veterinary practice where a cat was diagnosed with an OXA-23-producing A. baumannii ST2 strain. METHODS: Environmental samples together with nasal and hand swabs from the veterinary personnel were collected. All swabs were screened for the presence of extended-spectrum-ß-lactamase- and carbapenemase-producing Enterobacterales, meticillin-resistant staphylococcus and multi-drug-resistant Acinetobacter spp. Whole-genome sequencing was performed for carbapenemase-producing strains. RESULTS: Of the veterinary staff, 60% carried meticillin-resistant Staphylococcus epidermidis. Environmental evaluation showed that 40% (N=6/15) of the surfaces analysed by contact plates and 40% (N=8/20) by swabs failed the hygiene criteria. Assessment of the surfaces revealed contamination with five OXA-23-producing Acinetobacter spp. strains: an OXA-23-producing Acinetobacter schindleri on the weight scale in the waiting room; and four OXA-23-producing Acinetobacter lwoffii strains, on different surfaces of the treatment room. The blaOXA-23 gene was located on the same plasmid-carrying Tn2008 across the different Acinetobacter spp. strains. These plasmids closely resemble a previously described OXA-23-encoding plasmid from a human Portuguese nosocomial Acinetobacter pittii isolate. Distinctly, the OXA-23-producing A. baumannii ST2 clinical strain had the resistant gene located on Tn2006, possibly inserted on the chromosome. CONCLUSION: The detection of an OXA-23-producing A. baumannii ST2 veterinary clinical strain is of concern for companion animal health and infection, prevention and control. This study established the dynamic of transmission of the plasmid-mediated blaOXA-23 gene on critical surfaces of a small animal veterinary practice. The genetic resemblance to a plasmid found in human nosocomial settings suggests a potential One Health link.

Multi-drug Resistant Acinetobacter baumannii: Phenotypic and Genotypic Resistance Profiles and the Associated Risk Factors in Teaching Hospital in Jordan.

BACKGROUND: This study aimed to determine the prevalence of Antimicrobial Resistance Genes (ARGs), with a focus on colistin resistance in clinical A. baumannii, as well as the risk factors associated with A. baumannii infection in Jordanian patients. METHODS: In total, 150 A. baumannii isolates were obtained from patients at a teaching hospital. The isolates were tested for antimicrobial susceptibility using disc diffusion and microdilution methods. PCR amplification was used to detect ARGs, and statistical analysis was conducted to evaluate the influence of identified risk factors on the ARGs acquisition. RESULTS: More than 90% of A. baumannii isolates were resistant to monobactam, carbapenem, cephalosporins, Fluoroquinolones, penicillin, and ß-lactam agents. Moreover, 20.6% of the isolates (n = 31) were colistin-resistant. Several ARGs were also detected in A. baumannii isolates. Univariate analysis indicated that risk factors and the carriage of ARGs were significantly associated P ≤ (0.05) with gender, invasive devices, immunodeficiency, systemic diseases, tumors, and covid-19. Logistic regression analysis indicated seven risk factors, and three protective factors were associated with the ARGs (armA, strA, and strB) P ≤ (0.05). In contrast, tetB and TEM were associated with 2 risk factors each P ≤ (0.05). CONCLUSION: Our study indicates a high prevalence of MDR A. baumannii infections in ICU patients, as well as describing the case of colistin-resistant A. baumannii for the first time in Jordan. Additionally, the risk factors associated with ARGs-producing A. baumannii infections among ICU patients suggest a rapid emergence and spread of MDR A. baumannii without adequate surveillance and control measures.

Novel sequence type of carbapenem-resistant Acinetobacter pittii ST1451 with enhanced virulence isolated from septicaemic neonates in India.

BACKGROUND: The clinical relevance of Acinetobacter pittii is increasing, but reports of this organism causing neonatal sepsis are rare. OBJECTIVES: To understand the mechanisms of resistance and virulence of A. pittii isolated from neonatal blood belonging to a novel sequence type. MATERIALS AND METHODS: Antibiotic susceptibility, MLST, WGS, phylogenomic comparison with a global collection of carbapenemase-harbouring A. pittii were done. To study the pathogenic potential of novel A. pittii, in vitro and in vivo assays were carried out. RESULTS AND DISCUSSION: Two novel multidrug-resistant A. pittii from neonatal blood belonging to a novel sequence type 1451 (ST1451) were isolated. WGS revealed that the isolates were almost similar (147 SNP distant) and harbouring two carbapenem resistance genes blaNDM-1 with upstream ISAba125 and downstream bleMBL along with blaOXA-58 with upstream ISAba3. Other resistance genes included blaADC-25, blaOXA-533, aph(3″)-Ib, aph(3')-VIa, aph(6)-Id, aac(3)-IId, mph(E), msr(E), sul2 and tet(39), different efflux pump genes and amino acid substitutions within GyrA (Ser81Leu) and ParC (Ser84Leu; Glu88Ala) were detected among the isolates. The study genomes were closely related to four strains belonging to ST119. The isolates showed biofilm production, serum resistance, growth under iron limiting condition, surface-associated motility and adherence to host cell. Isolates induced cytokine production in the host cell and showed mice mortality. DISCUSSION AND CONCLUSIONS: This study is the first report of the presence of blaNDM-1 in A. pittii from India along with another carbapenemase blaOXA-58. Emergence of highly virulent, multidrug-resistant A. pittii with attributes similar to A. baumannii calls for surveillance to identify the novel strains and their pathogenic and resistance potential.

Prevalence of colistin resistance in clinical isolates of Acinetobacter baumannii: a systematic review and meta-analysis.

INTRODUCTION: The development of colistin resistance in Acinetobacter baumannii during treatment has been identified in certain patients, often leading to prolonged or recurrent infections. As colistin, is the last line of therapy for A. baumannii infections that are resistant to almost all other antibiotics, colistin-resistant A. baumannii strains currently represent a significant public health threat, particularly in healthcare settings where there is significant selective pressure. AIM: The aim of this study was to comprehensively determine the prevalence of colistin resistance in A. baumannii from clinical samples. Regional differences in these rates were also investigated using subgroup analyses. METHOD: The comprehensive search was conducted using "Acinetobacter baumannii", "Colistin resistant" and all relevant keywords. A systematic literature search was performed after searching in PubMed, Embase, Web of Science, and Scopus databases up to April 25, 2023. Statistical analysis was performed using Stata software version 17 and sources of heterogeneity were evaluated using I2. The potential for publication bias was explored using Egger's tests. A total of 30,307 articles were retrieved. After a thorough evaluation, 734 studies were finally eligible for inclusion in the present systematic review and meta-analysis. RESULT: According to the results, the prevalence of resistance to colistin among A. baumannii isolates was 4% (95% CI 3-5%), which has increased significantly from 2% before 2011 to 5% after 2012. South America had the highest resistance rate to this antibiotic. The broth microdilution method had the highest level of resistance, while the agar dilution showed the lowest level. CONCLUSIONS: This meta-analysis found a low prevalence of colistin resistance among A. baumannii isolates responsible for infections worldwide from 2000 to 2023. However, there is a high prevalence of colistin-resistant isolates in certain countries. This implies an urgent public health threat, as colistin is one of the last antibiotics available for the treatment of infections caused by XDR strains of A. baumannii.

An outbreak of multi-drug-resistant Acinetobacter baumannii on a burns ICU and its control with multi-faceted containment measures.

BACKGROUND: Patients in burns centres are at high risk of acquiring multi-drug-resistant organisms (MDROs) due to the reduced skin barrier and long hospital stay. METHODS: This study reports the investigation and control of an outbreak of MDR Acinetobacter baumannii in a burns centre. The 27 patients hospitalized in the centre during the outbreak were screened regularly, and a total of 132 environmental samples were analysed to identify a potential source. Fourier-transform infra-red (FT-IR) spectroscopy and multi-locus sequence typing were applied to characterize the outbreak strain. RESULTS: Between August and November 2022, the outbreak affected eight patients, with 11 infections and three potentially related fatal outcomes. An interdisciplinary and multi-professional outbreak team implemented a bundle strategy with repetitive admission stops, isolation precaution measures, patient screenings, enhanced cleaning and disinfection, and staff education. FT-IR spectroscopy suggested that the outbreak started from a patient who had been repatriated 1 month previously from a country with high prevalence of MDR A. baumannii. Environmental sampling did not identify a common source. Acquisition of the outbreak strain was associated with a higher percentage of body surface area with burn lesions ≥2a [per percent increase: odds ratio (OR) 1.05, 95% confidence interval (CI) 0.99-1.12; P=0.09], and inversely associated with a higher nurse-to-patient ratio (per 0.1 increase: OR 0.34, 95% CI 0.10-1.12; P=0.06). CONCLUSIONS: Burn patients with a higher percentage of body surface area with burn lesions ≥2a are at high risk of colonization and infection due to MDROs, particularly during periods of high workload. A multi-faceted containment strategy can successfully control outbreaks due to MDR A. baumannii in a burns centre.

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.

Impact of antibiotic exposure on antibiotic-resistant Acinetobacter baumannii isolation in intensive care unit patients: a systematic review and meta-analysis.

BACKGROUND: Acinetobacter baumannii (AB) poses a significant threat to critically ill patients in intensive care units (ICUs). Although an association between antibiotic exposure and resistant AB is reported in the literature, a synthesis of evidence in ICU patients is still lacking. AIM: To summarize the evidence on the association between prior antibiotic exposure and the occurrence of resistant AB in ICU patients. METHODS: Online databases were searched for cohort and case-control studies providing data on the association of interest. Carbapenem/multidrug-resistant AB isolation was compared with non-isolation; carbapenem/multidrug-resistant AB was compared with carbapenem/antibiotic-susceptible AB; and extensively drug-resistant AB isolation was compared with non-isolation. Each comparison was subjected to a restricted maximum likelihood random-effects meta-analysis per antibiotic class, estimating pooled ORs. Stratified meta-analyses were performed by study design, outcome type and association-measure adjustment. FINDINGS: Overall, 25 high-quality studies were retrieved. Meta-analyses showed that carbapenem/multidrug-resistant AB isolation was associated with previous exposure to aminoglycosides, carbapenems, third-generation cephalosporines, glycylcyclines, and nitroimidazoles. Increased risk of isolation of carbapenem/multidrug-resistant AB isolation vs carbapenem/antibiotic-susceptible AB was shown for prior exposure to aminoglycosides, antipseudomonal penicillins, carbapenems, fluoroquinolones, glycopeptides, and penicillins. Third-generation cephalosporin exposure increased the risk of extensively drug-resistant AB isolation vs non-isolation. CONCLUSION: This systematic review clarifies the role of antibiotic use in antibiotic-resistant AB spread in ICUs, although for some antibiotic classes the evidence is still uncertain due to the small number of adjusted analyses, methodological and reporting issues, and limited number of studies. Future studies need to be carried out with standardized methods and appropriate reporting of multivariable models.

Contribution of active surveillance cultures to the control of hospital-acquired carbapenem-resistant Acinetobacter baumannii in an endemic hospital setting.

BACKGROUND: Despite the increasing rates of carbapenem-resistant Acinetobacter baumannii (CRAB) carriage among hospitalized patients in endemic settings, the role of active surveillance cultures and cohorting is still debated. We sought to determine the long-term effect of a multifaceted infection-control intervention on the incidence of CRAB in an endemic setting. METHODS: A prospective, quasi-experimental study was performed at a 670-bed, acute-care hospital. The study consisted of 4 phases. In phase I, basic infection control measures were used. In phase II, CRAB carriers were cohorted in a single ward with dedicated nursing and enhanced environmental cleaning. In phase III large-scale screening in high-risk units was implemented. Phase IV comprised a 15-month follow-up period. RESULTS: During the baseline period, the mean incidence rate (IDR) of CRAB was 44 per 100,000 patient days (95% CI, 37.7-54.1). No significant decrease was observed during phase II (IDR, 40.8 per 100,000 patient days; 95% CI, 30.0-56.7; P = .97). During phase III, despite high compliance with control measures, ongoing transmission in several wards was observed and the mean IDR was 53.9 per 100,000 patient days (95% CI, 40.5-72.2; P = .55). In phase IV, following the implementation of large-scale screening, a significant decrease in the mean IDR was observed (25.8 per 100,000 patient days; 95% CI, 19.9-33.5; P = .03). An overall reduction of CRAB rate was observed between phase I and phase IV (rate ratio, 0.6; 95% CI, 0.4-0.9; P < .001). CONCLUSIONS: The comprehensive intervention that included intensified control measures with routine active screening cultures was effective in reducing the incidence of CRAB in an endemic hospital setting.

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.

Evolutionary trends of carbapenem-resistant and susceptible Acinetobacter baumannii isolates in a major tertiary care setting from North India.

Emergence of carbapenem-resistant A. baumannii (CRAB) is a global, ongoing healthcare concern. CRAB is among the topmost priority pathogens, with various studies focusing on its global population structure and resistant allelic profiles. However, carbapenem-susceptible A. baumannii (CSAB) isolates are often overlooked due to their sensitivity to beta-lactams, which can provide important insights into origin of CRAB lineages and isolates. In the present study, we report genomic investigation of CRAB and CSAB coexisting in Indian hospital setting. MLST based population structure and phylogenomics suggest they mainly follow distinct evolutionary routes forming two phylogroups. PG-I exclusively for a successful clone (ST2) of CRAB and PG-II comprises diversified CSAB isolates except PG3373, which is CRAB. Additionally, there are few CRAB isolates not belonging to PG-I and sharing clonal relationship with CSAB isolates indicating role of genome plasticity towards extensive drug resistance in the nosocomial environment. Further, genealogical analysis depicts prominent role of recombination in emergence and evolution of a major CRAB lineage. Further, CRAB isolates are enriched in resistomes as compared to CSAB isolates, which were encoded on the genomic island. Such comparative genomic insights will aid in our understanding and localized management of rapidly evolving pandrug resistant nosocomial pathogens.

Insights into the epidemiology, risk factors, and clinical outcomes of carbapenem-resistant Acinetobacter baumannii infections in critically ill children.

Background and aims: Carbapenem-resistant Acinetobacter baumannii (CRAB) has become a leading cause of nosocomial infections with an increasing impact on critically ill patients, yet there is limited data on contributing factors. This study was aim to evaluate the prevalence and risk factors, and clinical outcomes of CRAB infections among critically ill children in a tertiary university teaching hospital in China. Methods: From January 2016 to December 2021, all children diagnosed with nosocomial Acinetobacter baumannii (A. baumannii) infections in the pediatric intensive care unit (PICU) were identified through the computerized microbiology laboratory databases. Among them, children suffering from CRAB infection were designated as a case group, while children with carbapenem susceptible A. baumannii (CSAB) infection were assigned to a control group. This retrospective case-control study was based on two groups of patients to determine potential clinical factors contributing to CRAB infection and death among critically ill children via univariate and multivariate analyses. Results: During the 6-year study period, a total of 372 episodes of nosocomial A. baumannii infection in the PICU were eligible and included in the study. These isolates displayed moderate or high rates of resistance to all tested antimicrobials except colistin. The overall prevalence of CRAB and MDRAB (multidrug-resistant A. baumannii) was 78.0% and 80.9%, respectively. Several risk factors found to significantly increase CRAB infection included receiving invasive operation (OR = 9.412, p = 0.001), gastric intubation (OR = 2.478, p = 0.026), prior carbapenems exposure (OR = 2.543, p = 0.003), severe pneumonia (OR = 3.235, p = 0.001), and hemoglobin <110g/L (OR = 3.049, p = 0.005). Of 372 patients with CRAB infection, the mortality rate was 30.9% (115/372) and mortality did not differ between children with CRAB and CSAB infections. Septic shock (OR = 2.992, p = 0.001), AST > 46U/L (OR = 2.015, p = 0.005), bone marrow aspiration (OR = 2.704, p = 0.008), lymphocyte <20 % (OR = 1.992, p = 0.006) and age (OR = 1.094, p = 0.002) were independent risk factors for the death of A. baumanni infection. Conclusions: This study highlights considerable incidence rate and remarkable mortality of children with A. baumanni (especially CRAB) infections, and identifies age-specific risk factors for CRAB infection and mortality in critically ill children. These risk factors should be taken into account in pediatric hospitals in order to establish early intervention and rational treatment to improve clinical outcomes.

Colistin-induced structural and biochemical changes in carbapenem-resistant Acinetobacter baumannii isolated from the hospital environment.

BACKGROUND: Acinetobacter baumannii is an emerging multidrug-resistant bacterium and is considered as one of the important causes of nosocomial infections. OBJECTIVES: The main objectives are to determine the drug-resistant pattern of beta-lactamase-producing A. baumannii, colistin-induced structural and biochemical changes. METHODS: A. baumannii strains were isolated from the restrooms using the selective media, viz., restroom door, restroom floor, washing area, and restroom tap. A total of 120 samples were collected from all four sampling sites. These strains and their drug-resistance patterns were identified. Then carbapenem-resistance was analyzed and the occurrence of the drug-resistant gene (blaOXA-23) was determined. Colistin was applied at various concentrations (20 - 100 µg/mL) and the molecular mechanism of A. baumannii was analysed. RESULTS: The bacterial population was high on doors (53 ±â€¯2 CFU/mL), followed by restroom tap (19 ±â€¯1 CFU/mL), restroom floor (14 ±â€¯3 CFU/mL), and washing area (3 ±â€¯0 CFU/mL), respectively. A total of 343 A. baumannii strains were isolated from the 120 samples obtained for one year from the restroom. The isolated bacteria showed resistance to selected carbapenems, with 100% isolates being resistant to imipenem, followed by cefotaxime (1.4 ±â€¯0.2% susceptibility). More blaOXA-23 gene carrying strains were isolated from restroom tap(89 ±â€¯2.1%) than other sources. Colistin exhibited bactericidal activity against drug-resistant A. baumannii. Treating A. baumannii strain with 100 µg/mL colistin induced cell membrane roughness in vitro. Scanning Electron Microscopy (SEM) analysis revealed moderate cell shrinkage after treatment with colistin. Bacterial cells treated with hydrogen peroxide or colistin for 30 min induced the production of hydroxyl radicals. The bacterial lysis increased fluorescence and hydroxyl radicals, and released cellular protein and sugars. CONCLUSIONS: The isolated A. baumannii was resistant to imipenem and showed susceptibility to colistin. Colistin disrupted cell membrane in drug-resistant A. baumannii in vitro. The regular screening for drug-resistance among A. baumannii strains can help monitor the outbreak of A. baumannii and manage control measures.

Acinetobacter baumannii: assessing susceptibility patterns, management practices, and mortality predictors in a tertiary teaching hospital in Lebanon.

BACKGROUND: Acinetobacter baumannii is a major nosocomial pathogen capable of causing life-threatening infections. This bacterium is highly resistant to antibiotics and associated with high mortality rates. Therefore, this study aimed to evaluate A. baumannii's susceptibility patterns to antimicrobials, assess the appropriateness of the initiated antimicrobial therapy, determine the mortality rate, and identify predictors associated with mortality. METHODS: A retrospective observational study was conducted among patients infected with A. baumannii at a university hospital in Lebanon through the revision of medical records. Kaplan-Meier survival analysis and log-rank tests were used to analyze time-to-mortality. Binary logistic regression was performed to identify predictors of mortality. RESULTS: The records of 188 patients were screened, and 111 patients with A. baumannii infection were enrolled. Almost all isolates were resistant to carbapenem, and 43% of the isolates were extensively-drug resistant. Almost half of the patients received initial inappropriate antimicrobial therapy (n = 50, 45.1%). The 30-day mortality rate associated with A. baumannii infection was 71.2% (79/111). The time to mortality in patients who received inappropriate antimicrobial therapy (5.70 ± 1.07 days) was significantly shorter than in those who received appropriate antimicrobial therapy (12.43 ± 1.01 days, P < 0.01). Binary logistic regression revealed that inappropriate antimicrobial therapy (adjusted odds ratio [AOR] = 16.22, 95% CI 2.68-9.97, P = 0.002), mechanical ventilation (AOR = 14.72, 95% CI 3.27-6.61, P < 0.001), and thrombocytopenia (AOR = 8.82, 95% CI 1.12-9.75, P = 0.003) were more likely associated with mortality. CONCLUSIONS: A. baumannii exhibits an alarming mortality rate among infected patients. Thrombocytopenia, mechanical ventilation, and inappropriate antibiotic administration are associated with mortality in patients infected with A. baumannii. The prompt initiation of appropriate antimicrobial therapy, infection control measures, and effective stewardship program are crucial to reduce the incidence of A. baumannii and improve the treatment outcomes.

Prevalence of carbapenem resistance in Acinetobacter baumannii and Pseudomonas aeruginosa in sub-Saharan Africa: A systematic review and meta-analysis.

Carbapenems are effective drugs against bacterial pathogens and resistance to them is considered a great public health threat, especially in notorious nosocomial pathogens like Acinetobacter baumannii and Pseudomonas aeruginosa. In this study, we aimed to determine the prevalence of carbapenem resistance in A. baumannii and P. aeruginosa infections in Sub-Saharan Africa. Databases (PubMed, Scopus, Web of Science, and African Journal Online) were systematically searched following the Preferred Reporting Items for Systematic review and meta-analysis protocols (PRISMA-P) 2020 statements for articles reporting carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) prevalence between 2012 and 2022. Pooled prevalence was determined with the random effect model and funnel plots were used to determine heterogeneity in R. A total of 47 articles were scanned for eligibility, among which 25 (14 for carbapenem-resistant A. baumannii and 11 for carbapenem-resistant P. aeruginosa) were included in the study after fulfilling the eligibility criteria. The pooled prevalence of CRPA in the present study was estimated at 8% (95% CI; 0.02-0.17; I2 = 98%; P <0.01). There was high heterogeneity (Q = 591.71, I2 = 98.9%; P<0.0001). In addition, this study's pooled prevalence of CRAB was estimated at 20% (95% CI; 0.04-0.43; I2 = 99%; P <0.01). There was high heterogeneity (Q = 1452.57, I2 = 99%; P<0.0001). Also, a funnel plot analysis of the studies showed high degree of heterogeneity. The carbapenemase genes commonly isolated from A. baumannii in this study include blaOXA23, blaOXA48, blaGES., blaNDM, blaVIM, blaOXA24, blaOXA58, blaOXA51, blaSIM-1, blaOXA40, blaOXA66, blaOXA69, blaOXA91, with blaOXA23 and blaVIM being the most common. On the other hand, blaNDM, blaVIM, blaIMP, blaOXA48, blaOXA51, blaSIM-1, blaOXA181, blaKPC, blaOXA23, blaOXA50 were the commonly isolated carbapenemase genes in P. aeruginosa, among which blaVIM and blaNDM genes were the most frequently isolated. Surveillance of drug-resistant pathogens in Sub-Saharan Africa is essential in reducing the region's disease burden. This study has shown that the region has significantly high multidrug-resistant pathogen prevalence. This is a wake-up call for policymakers to put in place measures to reduce the spread of these critical priority pathogens.

Acinetobacter spp. bloodstream infection in hematological patients: a 10-year single-center study.

PURPOSE: This study investigated the clinical and antimicrobial characteristics of Acinetobacter spp. bloodstream infection (BSI) in hematological patients. Risk factors for 30-day mortality and carbapenem-resistant Acinetobacter spp. (CRA) BSI acquisition were also identified. METHODS: We reviewed forty hematological patients with Acinetobacter spp. BSI in a large Chinese blood disease hospital between 2013 and 2022. The remaining CRA isolates were subjected to whole-genome sequencing. RESULTS: The 30-day mortality rate was high at 35%. Hematological patients with Acinetobacter spp. BSI often presented with severe conditions and co-infections at multiple sites. All strains were colistin-susceptible and 40.0% were CR. Multivariate analysis identified several risk factors associated with CRA BSI acquisition, including previous exposure to carbapenems within 30 days and CRA colonization. Very severe aplastic anaemia, tetracycline-resistant Acinetobacter spp. BSI, and unresolved neutropenia after infection were closely associated with 30-day mortality. Non-survivors often presented with higher median PCT and CRP levels and severe complications, such as intracranial infection, cardiac dysfunction, respiratory failure, and severe sepsis or septic shock. Our study also identified inappropriate empirical antibiotic therapy as an independent predictor of 30-day mortality (OR: 11.234, 95% CI: 1.261-20.086, P = 0.030). This study was the first to report A. oleivorans as a human pathogen, and to identify its unique oxacillinase, OXA-325. CONCLUSION: An environment-originated non-pathogenic species can become pathogenic when the body's immunity is compromised. Our results also highlighted the importance of improving neutropenia after infection, treating severe organ dysfunction, and administering appropriate empirical antibiotic therapy to reduce mortality in this patient population.

Prevalence of Acinetobacter baumannii and Candida auris in Patients Receiving Mechanical Ventilation.

Importance: To date, only 1 statewide prevalence survey has been performed for Acinetobacter baumannii (2009) in the US, and no statewide prevalence survey has been performed for Candida auris, making the current burden of these emerging pathogens unknown. Objective: To determine the prevalence of A baumannii and C auris among patients receiving mechanical ventilation in Maryland. Design, Setting, and Participants: The Maryland Multi-Drug Resistant Organism Prevention Collaborative performed a statewide cross-sectional point prevalence of patients receiving mechanical ventilation admitted to acute care hospitals (n = 33) and long-term care facilities (n = 18) between March 7, 2023, and June 8, 2023. Surveillance cultures (sputum, perianal, arm/leg, and axilla/groin) were obtained from all patients receiving mechanical ventilation. Sputum, perianal, and arm/leg cultures were tested for A baumannii and antibiotic susceptibility testing was performed. Axilla/groin cultures were tested by polymerase chain reaction for C auris. Main Outcomes and Measures: Prevalence of A baumannii, carbapenem-resistant A baumannii (CRAB), and C auris. Prevalence was stratified by type of facility. Results: All 51 eligible health care facilities (100%) participated in the survey. A total of 482 patients receiving mechanical ventilation were screened for A baumannii and 470 were screened for C auris. Among the 482 patients who had samples collected, 30.7% (148/482) grew A baumannii, 88 of the 148 (59.5%) of these A baumannii were CRAB, and C auris was identified in 31 of 470 (6.6%). Patients in long-term care facilities were more likely to be colonized with A baumannii (relative risk [RR], 7.66 [95% CI, 5.11-11.50], P < .001), CRAB (RR, 5.48 [95% CI, 3.38-8.91], P < .001), and C auris (RR, 1.97 [95% CI, 0.99-3.92], P = .05) compared with patients in acute care hospitals. Nine patients (29.0%) with cultures positive for C auris were previously unreported to the Maryland Department of Health. Conclusions: A baumannii, carbapenem-resistant A baumannii, and C auris were common among patients receiving mechanical ventilation in both acute care hospitals and long-term care facilities. Both pathogens were significantly more common in long-term care facilities than in acute care hospitals. Patients receiving mechanical ventilation in long-term care facilities are a high-risk population for emerging pathogens, and surveillance and prevention efforts should be targeted to these facilities.

The multifaceted genus Acinetobacter: from infection to bioremediation.

Acinetobacter is a vast bacterial genus comprising of numerous species with variable characteristics. The enigma associated with clinical strains that have been implicated in many nosocomial outbreaks has prompted the need for continuous research on pathogens like Acinetobacter baumannii and members of the ACB complex. However, numerous species of Acinetobacter genus possess diverse metabolic capabilities and have the potential for a plethora of industrial and environment-based applications. Therefore, a comprehensive review on the entire genus, including many under-represented topics, would contribute extensive information to the scientific community indulged in Acinetobacter research. The current review is a unique compilation that attempts to provide the latest update on the genus covering its clinical as well as ecological aspects. Moreover, it is the first study of its kind that focuses on the entire genus and elaborates on the phylogenetic relationships, pathogenesis, and virulence mechanisms, followed by emerging biotechnological applications with future directions.