Frequency of Metalo beta Lactamase genes, bla IMP1, INT 1 in Acinetobacter baumanii isolated from burn patients North of Iran

Outer membrane vesicles in gram-negative bacteria and its correlation with pathogenesis

There is a widespread distribution of gram-negative bacteria worldwide, which are responsible for the deaths of numerous patients each year. The illnesses they cause can be localized and systemic, and these bacteria possess several key virulence factors that contribute to their pathogenicity. In recent years, several distinct mechanisms of pathogenesis have evolved that remain largely unknown to scientists and medical experts. Among these, outer membrane vesicles (OMVs) are undoubtedly one of the most significant factors influencing virulence. OMVs contain various bacterial compounds and can have diverse effects on host organisms and the immune system, potentially exacerbating disease and inflammation while evading immune responses. This review comprehensively examines the role of OMVs in bacterial pathogenesis, their interaction with host cells, and their potential biomedical applications. Understanding the molecular mechanisms governing OMV biogenesis and function could pave the way for novel antimicrobial strategies and therapeutic interventions.

Geographical mapping and temporal trends of Acinetobacter baumannii carbapenem resistance: A comprehensive meta-analysis

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) is of critical concern in healthcare settings, leading to limited treatment options. In this study, we conducted a comprehensive meta-analysis to assess the prevalence of CRAB by examining temporal, geographic, and bias-related variations.

METHODS

We systematically searched prominent databases, including Scopus, PubMed, Web of Science, and EMBASE. Quality assessment was performed using the JBI checklist. Subgroup analyses were performed based on the COVID-19 timeframes, years, countries, continents, and bias levels, antimicrobial susceptivity test method and guidelines.

RESULTS

Our comprehensive meta-analysis, which included 795 studies across 80 countries from 1995 to 2023, revealed a surge in carbapenem resistance among A. baumannii, imipenem (76.1%), meropenem (73.5%), doripenem (73.0%), ertapenem (83.7%), and carbapenems (74.3%). Temporally, 2020-2023 witnessed significant peaks, particularly in carbapenems (81.0%) and meropenem (80.7%), as confirmed by meta-regression, indicating a steady upward trend.

CONCLUSION

This meta-analysis revealed an alarmingly high resistance rate to CRAB as a global challenge, emphasizing the urgent need for tailored interventions. Transparency, standardized methodologies, and collaboration are crucial for the accurate assessment and maintenance of carbapenem efficacy.

Antibacterial and anti-biofilm properties of carvacrol alone and in combination with cefixime against Escherichia coli

BACKGROUND

Plant-derived compounds can be used as antimicrobial agents in medicines and as food preservatives. These compounds can be applied along with other antimicrobial agents to strengthen the effect and/or reduce the required treatment dose.

RESULTS

In the present study, the antibacterial, anti-biofilm and quorum sensing inhibitory activity of carvacrol alone and in combination with the antibiotic cefixime against Escherichia coli was investigated. The MIC and MBC values for carvacrol were 250 μg/mL. In the checkerboard test, carvacrol showed a synergistic interaction with cefixime against E. coli (FIC index = 0.5). Carvacrol and cefixime significantly inhibited biofilm formation at MIC/2 (125 and 62.5 μg/mL), MIC/4 (62.5 and 31.25 μg/mL) and MIC/8 (31.25 and 15.625 μg/mL) for carvacrol and cefixime, respectively. The antibacterial and anti-biofilm potential effect of carvacrol confirmed by the scanning electron microscopy. Real-time quantitative reverse transcription PCR revealed significant down-regulation of the luxS and pfs genes following treatment with a MIC/2 (125 μg/mL) concentration of carvacrol alone and of only pfs gene following treatment with MIC/2 of carvacrol in combination with MIC/2 of cefixime (p < 0.05).

CONCLUSIONS

Because of the significant antibacterial and anti-biofilm activity of carvacrol, the present study examines this agent as an antibacterial drug of natural origin. The results indicate that in this study the best antibacterial and anti-biofilm properties are for the combined use of cefixime and carvacrol.

The Spread of Insertion Sequences Element and Transposons in Carbapenem Resistant Acinetobacter baumannii in a Hospital Setting in Southwestern Iran

BACKGROUND

Acinetobacter baumannii is one of the most important hospital pathogenic bacteria that cause infectious diseases. The present study aimed to determine the frequency of carbapenem resistance genes in association with transposable elements and molecular typing of carbapenem-resistant A. baumannii bacteria collected from patients in Shiraz, Iran.

MATERIALS AND METHODS

A total of 170 carbapenem-resistant A. baumannii isolates were obtained from different clinical specimens in two hospitals. The minimum inhibitory concentrations (MIC) of imipenem were determined and the prevalence of OXA Carbapenemases, Metallo-β-lactamases genes, insertion sequences (IS) elements, and transposons were evaluated by the polymerase chain reaction (PCR) method. Finally, molecular typing of the isolates was performed by the Enterobacterial Repetitive Intergenic Consensus-PCR method.

RESULTS

The MICs ranged from 16 to 1,024 µg/mL for imipenem-resistant A. baumannii isolates. Out of the 170 carbapenem resistant A. baumannii isolates, blaOXA-24-like (94, 55.3%) followed by blaOXA-23-like (71, 41.7%) were predominant. In addition, A. baumannii isolates carried blaVIM (71, 41.7%), blaGES (32, 18.8%), blaSPM (4, 2.3%), and blaKPC (1, 0.6%). Moreover, ISAba1 (94.2%) and Tn2009 (39.2%) were the most frequent transposable elements. Furthermore, (71, 44.0%) and (161, 94.7%) of the ISAba1 of the isolates were associated with blaOXA-23 and blaOXA-51 genes, respectively. Besides (3, 1.7%), (1, 0.6%) and (5, 2.9%) of blaOXA-23 were associated with IS18, ISAba4, and ISAba2, respectively. Considering an 80.0% cut off, clusters and four singletons were detected.

CONCLUSION

According to the results, transposable elements played an important role in the development of resistance genes and resistance to carbapenems. The results also indicated carbapenem-resistant A. baumannii bacteria as a public health concern.