Multidrug-resistant Acinetobacter Baumannii Research Articles

Practical synthesis of isoindolines yields potent colistin potentiators for multidrug-resistant Acinetobacter baumannii.

An efficient and practical one-pot synthesis of isoindolines from readily available starting materials was achieved under mild conditions by implementing an isoindole umpolung strategy. A variety of isoindolines were prepared with good to excellent yields. Biological screens of these identified compounds demonstrated that they are potent potentiators of colistin for multi-drug resistant Acinetobacter baumannii.

Characterization of genes involved in the iron acquisition system of multidrug-resistant Acinetobacter baumannii.

The high prevalence of virulence-associated genes observed in Acinetobacter baumannii isolates underscores the pathogenic potential of this bacterium. The presence of these genes confers enhanced survival, evasion of host defenses, and increased virulence. In this study, we investigate the presence and distribution of genes associated with virulence and assess the antimicrobial susceptibility patterns in clinical isolates of A. baumannii. This research focused on examining the 50 multi-drugs resistant (MDR) strains that were included in this investigation. The identification of these strains was validated using Oxa-51. The presence of the BauA and BasD genes was determined through conventional PCR techniques. The results derived from Oxa-51 PCR confirmed the identification of all 50 selected strains of A. baumannii. Additionally, both the BauA and BasD genes were successfully identified in 82% of the MDR strains. Moreover, the varying antibiotic resistance patterns highlight the challenge in treating A. baumannii infections effectively. Strategies such as combination therapy, antimicrobial stewardship, and infection control measures should be considered to combat this multidrug-resistant pathogen.

Outbreak of Multidrug-resistant Acinetobacter baumannii in a Tertiary Health Center from Northwestern Nigeria.

In spite of its global notoriety and WHO alarm, Acinetobacter baumannii is still an understudied critical-priority pathobiont in Nigeria. We characterized its antimicrobial susceptibility profile and resistance genes during an outbreak. This cross-sectional study involved collection of patients' urine samples and swabs from unit staff's hands and ward environments for the identification of A. baumannii strains using standard morphologic and biochemical methods. The disk diffusion method was used to assess the antimicrobial susceptibility profile of the isolates with the production of extended-spectrum beta-lactamases (ESBLs) confirmed by the combined disk test screening method. Characterization of the resistance genes of the ESBL producers was carried out using polymerase chain reaction polymerase chain reaction technique. A. MDR strains of A. baumannii harboring blaSHV and blaTEM genes were recovered from clinical and environmental sources during the outbreak, which was contained with preventive measures recommended.

Phenotypic and Molecular Characterization of Hypervirulent and Multidrug-Resistant Acinetobacter baumannii Isolated from ICU Respiratory Infections.

The emergence of hypervirulent strains of Acinetobacter baumannii poses a significant threat in intensive care units (ICU). This study aimed to molecularly characterize hypervirulent A. baumannii strains isolated from ICU patients with respiratory infections. Six strains were isolated from ICU patients over one month. Isolates were identified by phenotypic characterization biochemical properties and 16s RNA sequencing. Antibiotic susceptibility testing was conducted followed by resistance genes detection by PCR. MLST, and PFGE were employed to analyse clonal relationships among strains. Plasmid replicon typing and plasmid transmission frequencies were determined. The isolated strains exhibited diverse clinical manifestations, including acute respiratory distress syndrome (ARDS). Antibiotic susceptibility testing revealed multidrug-resistance phenotype. Molecular analysis revealed a complex genetic landscape of antibiotic resistance genes, including ESBLs and carbapenemases, as well as virulence genes such as ompA, csuE, and exoS. The multiple sequence types indicating genetic diversity among the strains as ST1512, ST622, and ST149 (each type two isolates). Plasmid characterization revealed the presence of diverse replicon types associated with multidrug resistance. This study provides comprehensive insights into the phenotypic, molecular, and epidemiological characteristics of hypervirulent A. baumannii outbark in ICU.

A thermosensitive hydrogel formulation of phage and colistin combination for the management of multidrug-resistant Acinetobacter baumannii wound infections.

Chronic skin wounds are often associated with multidrug-resistant bacteria, impeding the healing process. Bacteriophage (phage) therapy has been revitalized as a promising strategy to counter the growing concerns of antibiotic resistance. However, phage monotherapy also faces several application drawbacks, such as a narrow host spectrum, the advent of resistant phenotypes and poor stability of phage preparations. Phage-antibiotic synergistic (PAS) combination therapy has recently been suggested as a possible approach to overcome these shortcomings. In the present study, we employed a model PAS combination containing a vB_AbaM-IME-AB2 phage and colistin to develop stable wound dressings of PAS to mitigate infections associated with Acinetobacter baumannii. A set of thermosensitive hydrogels were synthesized with varying amounts of Pluronic® F-127 (PF-127 at 15, 17.5 and 20 w/w%) modified with/without 3 w/w% hydroxypropyl methylcellulose (HPMC). Most hydrogel formulations had a gelation temperature around skin temperature, suitable for topical application. The solidified gels were capable of releasing the encapsulated phage and colistin in a sustained manner to kill bacteria. The highest bactericidal effect was achieved with the formulation containing 17.5% PF-127 and 3% HPMC (F5), which effectively killed bacteria in both planktonic (by 5.66 log) and biofilm (by 3 log) states and inhibited bacterial regrowth. Good storage stability of F5 was also noted with negligible activity loss after 9 months of storage at 4 °C. The ex vivo antibacterial efficacy of the F5 hydrogel formulation was also investigated in a pork skin wound infection model, where it significantly reduced the bacterial burden by 4.65 log. These positive outcomes warrant its further development as a topical PAS-wound dressing.

Phage-encoded depolymerases as a strategy for combating multidrug-resistant Acinetobacter baumannii.

Acinetobacter baumannii, a predominant nosocomial pathogen, represents a grave threat to public health due to its multiple antimicrobial resistance. Managing patients afflicted with severe infections caused by multiple drug-resistant A. baumannii is particularly challenging, given the associated high mortality rates and unfavorable prognoses. The diminishing efficacy of antibiotics against this superbug underscores the urgent necessity for novel treatments or strategies to address this formidable issue. Bacteriophage-derived polysaccharide depolymerase enzymes present a potential approach to combating this pathogen. These enzymes target and degrade the bacterial cell's exopolysaccharide, capsular polysaccharide, and lipopolysaccharide, thereby disrupting biofilm formation and impairing the bacteria's defense mechanisms. Nonetheless, the narrow host range of phage depolymerases limits their therapeutic efficacy. Despite the benefits of these enzymes, phage-resistant strains have been identified, highlighting the complexity of phage-host interactions and the need for further investigation. While preliminary findings are encouraging, current investigations are limited, and clinical trials are imperative to advance this treatment approach for broader clinical applications. This review explores the potential of phage-derived depolymerase enzymes against A. baumannii infections.

Drug Repurposing against Anhydro-N-acetylmuramic Acid Kinase of Multi-Drug Resistant Acinetobacter baumannii: An in Silico Approach

ABSTRACT: Acinetobacter baumannii, a gram-negative coccobacillus is accountable for different nosocomial diseases. It has been enlisted in the ‘critical’ category in WHO published list depending on the urgency for novel drug development as it becomes multidrug resistant (MDR). The aim of this study was to find a drug which can be repurposed against any drug target of these bacteria and thus the time and cost required for typical drug development procedure can be bypassed. In this study, Anhydro-N-acetylmuramic acid kinase (AnmK) of Acinetobacter baumannii was analyzed to be a good drug target which is responsible for the structural integrity of the cell wall of these bacteria. The expression probability of the protein is high with 0.916. PROTPARAM analysis shows that it is a thermostable, non polar protein with molecular weight of 41.7 kDa and pI in the acidic range. The structure prediction was done with SWISS-MODEL (with 46.71% identity with the template) and was found reliable with 91.8% amino acid in allowable region. This predicted structure was used for dug repurposing in which drugs are screened from ZINC15 database (containing FDA approved drug) to find their effective binding (if any) with this protein. PyRx software was used for the docking process which found Ergotamine as the most promising repurposed drug in terms of binding energy(-10.5 kcal/mole) and vina score(-10.3 kcal/mole). Molecular Dynamics Simulation shows that binding of this drug with the protein target is stable over picoseconds time scale.

Detection of Multidrug-Resistant Acinetobacter baumannii among Gram-Negative Bacteria Isolated from Clinical Samples

Detection of Multidrug-Resistant Acinetobacter baumannii among Gram-Negative Bacteria Isolated from Clinical Samples

In vitro activity of cefiderocol and comparator antibiotics against multidrug-resistant non-fermenting Gram-negative bacilli.

This study evaluated the in vitro activity of cefiderocol, ceftazidime/avibactam, and aztreonam/avibactam against clinically important multidrug-resistant non-fermenting Gram-negative bacilli. Bacteraemic isolates of 126 multidrug-resistant Acinetobacter baumannii (MDRAB), 110 imipenem-resistant Pseudamoas aeruginosa [including 14 difficult-to-treat resistant P. aeruginosa (DTRPA)], 45 beta-lactam-non-susceptible Burkholderia cepacia complex (BCC), 47 levofloxacin or trimethoprim/sulfamethoxazole-non-susceptible Stenotrophomonas maltophilia and 22 ciprofloxacin-non-susceptible Elizabethkingia spp. collected between 2019 and 2021 were subjected to MIC determination for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam. The MIC50/90s of cefiderocol for drug-resistant A. baumannii, P. aeruginosa, BCC, S. maltophilia and Elizabethkingia spp. were 0.25/2, 0.25/1, ≤0.06/≤0.06, ≤0.06/0.25 and >32/>32 mg/L, respectively. Cefiderocol inhibited 94.4% (119/126) of MDRAB, 100% of imipenem-resistant P. aeruginosa, 100% of DTRPA and 100% of BCC at an MIC ≤4 mg/L, and 97.9% (46/47) of S. maltophilia at ≤1 mg/L. Ceftazidime/avibactam inhibited 76.4% (84/110) of imipenem-resistant P. aeruginosa, 21.4% (3/14) of DTRPA and 68.9% (31/45) of BCC at an MIC ≤8 mg/L. Aztreonam/avibactam had MIC50/90s of 16/>32, 8/16 and 4/8 mg/L for imipenem-resistant P. aeruginosa, BCC and S. maltophilia, respectively. At ≤8 mg/L, aztreonam/avibactam inhibited 7.1% (1/14) of DTRPA and 93.6% (44/47) of S. maltophilia isolates. Elizabethkingia spp. demonstrated high MICs for cefiderocol, ceftazidime/avibactam and aztreonam/avibactam, with all MIC50s and MIC90s > 32 mg/L. Cefiderocol may serve as an alternative treatment for multidrug-resistant A. baumannii, P. aeruginosa, BCC and S. maltophilia when other antibiotics have been ineffective or intolerable. The role of ceftazidime/avibactam and aztreonam/avibactam in the management of BCC or S. maltophilia infections warrants further investigation.

Exploring Roles of the Polysaccharide Capsule in Pathogenesis of Hypervirulent Acinetobacter baumannii Clinical Isolate Lac-4.

The frequently multidrug-resistant bacterial pathogen Acinetobacter baumannii is a leading cause of nosocomial infections, including ventilator-associated pneumonia, such that the World Health Organization and US Centers for Disease Control and Prevention have declared it a top priority candidate for novel drug development. Nearly all clinical A. baumannii strains express a thick surface polysaccharide capsule that protects against desiccation, host defenses, and disinfectants. In this study, we investigated the contribution of the polysaccharide capsule to virulence caused by the A. baumannii clinical isolate Ab Lac-4, which is rare in its ability to cause pneumonia and disseminated sepsis in healthy mice. We assessed the role of the capsule in wildtype Lac-4 (WT) by generating a premature stop codon in wza, which codes for the polysaccharide export protein. The wza# mutant was hypersensitive to killing by complement, whole blood, and healthy human neutrophils compared to WT and a revertant mutant (wza-Rev). Furthermore, the wza# mutant was highly attenuated in murine sepsis and unable to disseminate from the lungs during pneumonia. This study reinforces the capsule as a key contributor to Ab Lac-4 hypervirulence.

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

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. 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. 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. 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.

The impact of environmental cleaning protocol featuring PX-UV in reducing the incidence of multidrug-resistant gram-negative healthcare-associated infection and colonization in intensive care units in Thailand.

In this quasi-experimental study, implementing PX-UV to the standard environmental cleaning protocol was associated with a reduction in the overall incidence of multidrug-resistant (MDR) gram-negative organisms (P = .01) and MDR Acinetobacter baumannii (P = .001) in intervention intensive care units. However, the intervention did not reduce patient length of stay and 30-day mortality.

Fe3O4 NPs-encapsulated metal-organic framework/enzyme hybrid nanoreactor for drug-resistant bacterial elimination via enhanced chemodynamictherapy

As a potential tool for combating bacterial infections, chemodynamic therapy (CDT), which utilizes the highly toxic hydroxyl radical (•OH), has shown tremendous promise. Its antibacterial efficacy, however, is compromised by insufficient H2O2 levels and a near-neutral pH at infection sites. Herein, a glucose-fueled and H2O2 self-supplying •OH nanogenerator (GOx-Fe3O4@MIL) based on cascade catalytic reactions is successfully constructed by immobilizing glucose oxidase (GOx) on the surface of Fe3O4 NPs-encapsulated MIL88B–NH2. MIL88B–NH2 (MIL NPs), a peroxidase-mimicking enzyme, immobilizes and protects GOx while synergistically enhancing the CDT effect of Fe3O4 NPs. GOx can continuously convert glucose into gluconic acid and H2O2. The former reduces the pH value to approximately 4, at which point Fe3O4@ MIL NPs exhibit the highest reaction activity. The continually produced H2O2 is used for subsequent catalysis of activated Fe3O4 @MIL NPs to generate highly toxic •OH for antibacterial applications, avoiding the direct use of relatively high concentrated and toxic H2O2. In vitro and in vivo results indicate that the designed self-activated nanoreactor can significantly inhibit methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDR-AB) growth with negligible biotoxicity.

In vivo dose response and efficacy of the β-lactamase inhibitor, durlobactam, in combination with sulbactam against the Acinetobacter baumannii-calcoaceticus complex.

Multi-drug resistant (MDR) Acinetobacter baumannii is emerging as a pathogen of increasing prevalence and concern. Infections associated with this Gram-negative pathogen are often associated with increased morbidity and mortality and few therapeutic options. The β-lactamase inhibitor sulbactam used commonly in combination with ampicillin demonstrates intrinsic antibacterial activity against A. baumannii acting as an inhibitor of PBP1 and PBP3, which participate in cell wall biosynthesis. The production of β-lactamases, particularly class D oxacillinases, however, has limited the utility of sulbactam resorting to increased doses and the need for alternate therapies. Durlobactam is a non-β-lactam β-lactamase inhibitor that demonstrates broad β-lactamase inhibition including class D enzymes produced by A. baumannii and has shown potent in vitro activity against MDR A. baumannii, particularly carbapenem-resistant isolates in susceptibility and pharmacodynamic model systems. The objective of this study is to evaluate the exposure-response relationship of sulbactam and durlobactam in combination using in vivo neutropenic thigh and lung models to establish PK/PD exposure magnitudes to project clinically effective doses. Utilizing established PK/PD determinants of %T>MIC and AUC/MIC for sulbactam and durlobactam, respectively, non-linear regressional analysis of drug exposure was evaluated relative to the 24-hour change in bacterial burden (log10 CFU/g). Co-modeling of the data across multiple strains exhibiting a broad range of MIC susceptibility suggested net 1-log10 CFU/g0 reduction can be achieved when sulbactam T>MIC exceeds 50% of the dosing interval and durlobactam AUC/MIC is 10. These data were ultimately used to support sulbactam-durlobactam dose selection for Phase 3 clinical trials.

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.

The impact of COVID-19 on microbiological profile and antibiotic consumption in ICU: a retrospective study in an infectious disease hospital in Brazil

BackgroundThe COVID-19 pandemic has triggered crises in the public health sector that have complex and multifaceted interrelationships with antimicrobial resistance. It is important to evaluate the impact of COVID-19 on microbiological profile, antibiotic and alcohol gel consumption in Intensive Care Units (ICU). MethodsThis is a retrospective study undertaken in an infectious disease hospital located in Bahia/Brazil during three periods: from March 2019 to February 2020; from March 2020 to February 2021; and from March 2021 to February 2022. It was evaluated the incidence density of Candida spp and of multidrug-resistant Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species (ESKAPE group) in blood, urine and tracheal secretion isolated 48 h after the patient's admission to the ICU, as well as the use of alcohol gel (in milliliters) and consumption of antibiotics in Defined Daily Dose (DDD) per 1,000 ICU patient-days in the previous year and in the first two years of COVID-19 pandemic. ResultsThere was an increase in Candida spp. (5.81, p < 0.001, IRR = 10.47, 95 % CI 2.57‒42.62) and in carbapenem-resistant A. baumannii in clinical cultures (4.71, p < 0.001, IRR = 8.46, 95 % CI 2.07‒34.60), the latter mainly in tracheal secretions (3.18, p= 0.02, IRR = 11.47, 95 % CI 1.58‒83.39). A rise in the consumption of ceftriaxone and piperacillin-tazobactam, along with an increase in the utilization of alcohol gel were observed. ConclusionThe shifting microbiological profile can be attributed to both the unique characteristics of patients with COVID-19 and the adjustments made to healthcare facilities' structural and work routines. Understanding these changes is essential in addressing the accelerated impact of antimicrobial resistance during the pandemic. Therefore, conducting thorough reviews of institutional practices and routines becomes critical in mitigating the consequences of antimicrobial resistance and its implications for patient care.

An outbreak within an outbreak: The impact of Infection Prevention and Control strategies on hospital-acquired infections and the occurrence of multi-drug resistant organisms during the COVID-19 pandemic

Background. The coronavirus disease 2019 (COVID-19) pandemic placed an unprecedented strain on intensive care units (ICUs) in South Africa. Infection prevention and control (IPC) strategies were highlighted to minimise the risk to healthcare workers and for the protection of patients from contracting hospital-acquired infections (HAIs). During the third wave, our institution adopted a shift system to address severe burnout among ICU personnel. We noted an upstroke in the occurrence of HAIs, specifically carbapenem-resistant Enterobacterales (CRE) and multidrug-resistant (MDR) Acinetobacter baumannii. Objectives. To report these outbreaks, compare the rate of CRE and A. baumannii infections with the first COVID-19 wave and to analyse its impact on patient outcomes. Method. We retrospectively analysed data from a prospectively collected registry involving all adult patients with severe COVID-19 admitted to the dedicated COVID-19 ICU from May 2021 to September 2021. Information from the admission database, including the patients’ demographics, comorbidities, laboratory results and length of ICU stay were extracted. Results. Ninety patients were admitted with severe COVID-19 during the third wave. There was an outbreak of both CRE (the majority Klebsiella pneumoniae) and A. baumannii. Furthermore, 18 patients cultured the same CRE organism, and 25 patients cultured the environmental organism A. baumannii. The HAI rate was significantly higher compared with the first wave published data: 59/90 (65.6%) v. 73/363 (20.1%, p&lt;0.01). Patients with any HAI had a longer mean stay in ICU (10.1 days v. 6.7 days (p&lt;0.01) and a higher mortality of 48/59 (81%) v. 19/31 (61%) (p=0.05). Conclusion. We observed a very significant rise in HAIs in the COVID-19 ICU during the third wave compared with the first, with almost three times as many patients developing HAIs. Unsurprisingly, it was associated with a longer mean stay in ICU and a higher mortality. The outbreak of both CRE and A. baumannii, and the fact that many patients cultured the same CRE organism and A. baumannii, strongly suggests that a critical breakdown in IPC measures had occurred.

Structure-based identification of novel inhibitors targeting the enoyl-ACP reductase enzyme of Acinetobacter baumannii

Acinetobacter baumannii is a Gram-negative multidrug-resistant bacterial pathogen primarily associated with nosocomial infections resulting in increased morbidity and mortality in adults and infants, especially in sub-Saharan Africa where the clinical burden is high. New therapeutics are needed to treat multidrug-resistant Acinetobacter baumannii infections and reduce transmission. The study used computer-integrated drug discovery approaches including pharmacophore modelling, molecular docking, and molecular dynamics simulation to screen potential inhibitors against the enoyl-acyl carrier protein reductase—FabI protein of Acinetobacter baumannii. The top three potential inhibitors: 21272541 > 89795992 > 89792657 showed favourable binding free energies including coulombic energy, van der Waals energy, and polar and non-polar energies. Furthermore, all three complexes were extremely stable and compact with reduced fluctuations during the simulations period. Inhibitor 21272541 exhibited the highest binding affinity against the Acinetobacter baumannii FabI protein. This is similar to our recent report, which also identified 21272541 as the lead inhibitor against Klebsiella pneumoniae infections. Future clinical studies evaluating drug effectiveness should prioritise inhibitor 21272541 which could be effective in treating infections caused by Gram-negative organisms.

Molecular epidemiology and antimicrobial resistance patterns of carbapenem-resistant Acinetobacter baumannii isolates from patients admitted at ICUs of a teaching hospital in Zunyi, China.

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a predominant strain of healthcare-associated infections worldwide, particularly in intensive care units (ICUs). Therefore, it is imperative to study the molecular epidemiology of CRAB in the ICUs using multiple molecular typing methods to lay the foundation for the development of infection prevention and control strategies. This study aimed to determine the antimicrobial susceptibility profile, the molecular epidemiology and conduct homology analysis on CRAB strains isolated from ICUs. The sensitivity to various antimicrobials was determined using the minimum inhibitory concentration (MIC) method, Kirby-Bauer disk diffusion (KBDD), and E-test assays. Resistance genes were identified by polymerase chain reaction (PCR). Molecular typing was performed using multilocus sequence typing (MLST) and multiple-locus variable-number tandem repeat analysis (MLVA). Among the 79 isolates collected, they exhibited high resistance tovarious antimicrobials but showed low resistance to levofloxacin, trimethoprim-sulfamethoxazole, and tetracyclines. Notably, all isolates of A. baumannii were identified as multidrug-resistant A. baumannii (MDR-AB). The bla OXA-51-like, adeJ, and adeG genes were all detected, while the detection rates of bla OXA-23-like (97.5%), adeB (93.67%), bla ADC (93.67%), qacEΔ1-sul1 (84.81%) were higher; most of the Ambler class A and class B genes were not detected. MLST analysis on the 79 isolates identified five sequence types (STs), which belonged to group 3 clonal complexes 369. ST1145Ox was the most frequently observed ST with a count of 56 out of 79 isolates (70.89%). MLST analysis for non-sensitive tigecycline isolates, which were revealed ST1145Ox and ST1417Ox as well. By using the MLVA assay, the 79 isolates could be grouped into a total of 64 distinct MTs with eleven clusters identified in them. Minimum spanning tree analysis defined seven different MLVA complexes (MCs) labeled MC1 to MC6 along with twenty singletons. The locus MLVA-AB_2396 demonstrated the highest Simpson's diversity index value at 0.829 among all loci tested in this study while also having one of the highest variety of tandem repeat species. The molecular diversity and clonal affinities within the genomes of the CRAB strains were clearly evident, with the identification of ST1144Ox, ST1658Ox, and ST1646Oxqaq representing novel findings.

Real-life Data on Cefiderocol Efficacy and Safety to Treat Multidrug-Resistant Acinetobacter baumannii Infections.

The objective of this study was to expand real-life data on cefiderocol efficacy to treat multidrug-resistant Acinetobacter baumannii infections. This was a retrospective monocentric study including patients hospitalized (>24 hours) at Policlinico Tor Vergata, Rome, Italy, between May 1, 2021, and September 1, 2022, treated with cefiderocol (>48 hours). The primary objective was early clinical improvement at 48-72 hours from cefiderocol start; secondary objectives were clinical success (composite outcome of infection resolution and 14-day survival), breakthrough infection, overall 30-day mortality, and cefiderocol-related adverse events. Eleven patients were enrolled; 91% males (10/11), with a median age (interquartile range [IQR]) of 69 (59-71) years, 91% had ≥1 comorbidity, and 72.7% (8/11) were hospitalized in internal medicine wards. Six patients with bloodstream infection (54.5%; 4 primary, 2 central line-associated), 2 with pneumonia (18.2%), 2 with urinary tract infections (18.2%), and 1 with intra-abdominal infection (9.1%) were treated. Four patients (36.3%) presented with septic shock at cefiderocol start. Cefiderocol was used as monotherapy in 3/11 patients (27.3%), was combined with colistin in all the other 8 cases, and was used in triple combination with tigecycline in 2 patients. The median duration of treatment (IQR) was 12 (10-14) days. Early clinical improvement was documented in 8/11 patients (72.7%), clinical success in 8/11 patients (72.7%). Overall 30-day mortality was 27.3% (3/11), with death occurring a median (IQR) of 19 (17.5-20.5) days after the start of therapy. No cefiderocol-related adverse events were documented. Cefiderocol seems to be a safe and effective option for multidrug-resistant Acinetobacter baumannii infections.