High prevalence of multidrug-resistant non-fermentative Gram-negative bacilli harboring bla IMP-1 and bla VIM-1 metallo-beta-lactamase genes in Birjand, south-east Iran

Current trends in the epidemiology of multidrug-resistant and beta-lactamase-producing Pseudomonas aeruginosa in Asia and Africa: a systematic review and meta-analysis

Pseudomonas aeruginosa continues to be a significant contributor to high morbidity and mortality rates worldwide, particularly due to its role in severe infections such as hospital-acquired conditions, including ventilator-associated pneumonia and various sepsis syndromes. The global increase in antimicrobial-resistant (AMR) P. aeruginosa strains has made these infections more difficult to treat, by limiting the effective drug options available. This systematic review and meta-analysis aim to provide an updated summary of the prevalence of AMR P. aeruginosa over the past 5 years. A systematic search was performed across three major electronic databases-PubMed, ScienceDirect, and Web of Science-yielding 40 eligible studies published between 2018 and 2023. Using a random-effects model, our meta-analysis estimated that the overall prevalence of P. aeruginosa in Asia and Africa over the past 5 years was 22.9% (95% CI [14.4-31.4]). The prevalence rates for multidrug-resistant (MDR) and extensively drug-resistant (XDR) P. aeruginosa strains were found to be 46.0% (95% CI [37.1-55.0]) and 19.6% (95% CI [4.3-34.9]), respectively. Furthermore, the prevalence rates of extended-spectrum β-lactamase- and metallo-β-lactamase-producing P. aeruginosa were 33.4% (95% CI [23.6-43.2]) and 16.0% (95% CI [9.8-22.3]), respectively. Notably, resistance rates to β-lactams used for treating pseudomonal infections were alarmingly high, with rates between 84.4% and 100.0% for cephalosporins, and over 40% of P. aeruginosa isolates showed resistance to penicillins. Our analysis identified the lowest resistance rates for last-resort antimicrobials, with 0.3% (95% CI [0.0-1.3]) resistance to polymyxin B and 5.8% (95% CI [1.5-10.2]) to colistin/polymyxin E. The low resistance rates to polymyxins suggest that these antibiotics remain effective against MDR P. aeruginosa. However, the findings also highlight the critical public health threat posed by antimicrobial-resistant P. aeruginosa, particularly concerning β-lactam antibiotics. This underscores the need for effective and carefully planned intervention strategies, including the development of new antibiotics to address the growing challenge of resistance. Developing robust antibiotic treatment protocols is essential for better management and control of pseudomonal infections globally. Therefore, continued research and international collaboration is vital to tackle this escalating public health challenge. This study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO), under registration number CRD42023412839.

Relationship between antibiotic resistance with class 1 integron and SmeDEF efflux pump encoding genes in clinical isolates of Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an emerging multidrug-resistant organism with an increasing frequency of hospital-acquired infections predominantly in developing countries. The purpose of this study was to determine the antibiotic resistance and frequency of the smeD, class 1 integron, and sul1 genes in clinical isolates of S. maltophilia in two Iranian provinces. From January 2020 to September 2021, 38 clinical isolates of S. maltophilia were collected from patients in hospitals in Tabriz and Sanandaj provinces of Iran. S. maltophilia isolates were confirmed by standard bacteriological tests and 16S rRNA gene PCR. Disk diffusion and the MIC test strip methods were used to determine the antibiotic resistance patterns. PCR was performed to investigate the presence of smeD, class 1 integron, and sul1 genes. The antimicrobial test for the isolated S. maltophilia showed a high level of sensitivity against most of the antibiotics used. Maximum sensitivity was recorded for ciprofloxacin (100% (38/38)) and levofloxacin 100% (38/38), followed by ceftazidime (97.36% (37/38)), trimethoprim-sulfamethoxazole (81.57% (31/38)), ticarcillin-clavulanate (60.52% (23/38)), and piperacillin-tazobactam (55.26% (21/38)). We observed a high prevalence of smeD (100% (38/38)) and class 1 integron (94.73% (36/38)) genes in the isolates, and none of the isolates carried the sul1 gene. The findings from this study indicate that resistance to trimethoprim-sulfamethoxazole was not observed, and still, trimethoprim-sulfamethoxazole is the best drug with desirable antimicrobial effect in the treatment of nosocomial infections caused by S. maltophilia strains. Despite the observation of a high number of class 1 integron, the sul1 gene was not observed, which indicates the role of this gene in high-level trimethoprim-sulfamethoxazole resistance and not having a role in low-level resistance. Based on our results, clinical microbiology laboratories need continuous surveillance of resistance rates to trimethoprim-sulfamethoxazole, because of the possibility of S. maltophilia acquiring trimethoprim-sulfamethoxazole-resistance by mobile gen elements.

Emergence of Multidrug-Resistant Non-Fermenting Gram-Negative Bacilli in a Tertiary Care Teaching Hospital of Central India: Is Colistin Resistance Still a Distant Threat?

Purpose Multidrug-resistant (MDR) organisms are being increasingly reported from India. This study aimed to determine the antibiotic susceptibility pattern of non-fermenting Gram-negative bacilli (NF-GNB) isolated from all the clinical samples to estimate the prevalence of MDR MDR NF-GNB and to screen for colistin-resistance genes among all colistin-resistant strains. Materials and methods This prospective study conducted from January 2021 to July 2022 at a tertiary care teaching hospital in central India identified MDR NF-GNB from clinical samples using standard procedures and antimicrobial susceptibility testing conducted as per Clinical Laboratory Standards Institute (CLSI) guidelines. Colistin-resistant strains identified by broth microdilution were further subjected to detection of plasmid-mediated colistin-resistant genes (mcr-1, mcr-2, mcr-3) by polymerase chain reaction (PCR). Results A total 2,106 NF-GNB were isolated from 21,019 culture positive clinical samples, of which 743 (35%) were MDR. Majority of MDR NF-GNB isolated were from pus (45.50%) followed by blood (20.50%). Out of 743 non-duplicate MDR non-fermenters,the most common were Pseudomonas aeruginosa (51.7%), Acinetobacter baumannii (23.4%),and others (24.9%).Around5.2% Pseudomonas aeruginosa and 2.3% Acinetobacter baumannii were resistant to colistin, and 88.2% were resistant to ceftazidime. Burkholderia cepacia complexwas 100% susceptible to minocycline and least susceptible to ceftazidime (28.6%). Out of 11, 10 (90.9%) Stenotrophomonas maltophilia were susceptible to colistin and least susceptible to ceftazidime and minocycline (27.3%). All 33 colistin-resistant strains (minimal inhibitory concentration ≥ 4 µg/mL) were found to be negative for mcr-1, mcr-2, and mcr-3 genes. Conclusion Our study showed a significantly wide variety of NF-GNB, ranging from Pseudomonas aeruginosa (51.7%), Acinetobacter baumannii (23.4%),to Acinetobacter haemolyticus (4.6%), Pseudomonas putida (0.9%), Elizabethkingia meningoseptica (0.7%), Pseudomonas luteola (0.5%), and Ralstonia pickettii (0.4%), which have not been commonly reported in literature. Of all the non-fermenters isolated in the present study, 35.28% were MDR, raising the concern for rationalizing antibiotic use and improving infection control measures to avert or slow the emergence of antibiotic resistance.

Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii with Special Reference to Carbapenemases: A Systematic Review

Carbapenemases are β-lactamase enzymes that hydrolyze a variety of β-lactams including carbapenem and belong to different Ambler classes (A, B, D). These enzymes can be encoded by plasmid or chromosomal-mediated genes. The major issues associated with carbapenemases-producing organisms are compromising the activity and increasing the resistance to carbapenems which are the last resort antibiotics used in treating serious infections. The global increase of pathogen, carbapenem-resistant A. baumannii has significantly threatened public health. Thus, there is a pressing need for a better understanding of this pathogen, to know the various carbapenem resistance encoding genes and dissemination of resistance genes from A. baumannii which help in developing strategies to overcome this problem. The horizontal transfer of resistant determinants through mobile genetic elements increases the incidence of multidrug, extensive drug, and Pan-drug resistant A. baumannii. Therefore, the current review aims to know the various mechanisms of carbapenem resistance, categorize and discuss carbapenemases encoding genes and various mobile genetic elements, and the prevalence of carbapenemase genes in recent years in A. baumannii from various geographical regions.

Phenotypic and genotypic detection of resistance mechanisms in carbapenem-resistant gram-negative bacteria isolated from Egyptian ICU patients with first emergence of NDM-1 producing Klebsiella oxytoca

Background and Objectives

Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods.

Materials and Methods

Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB).

Results

Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-encoding genes, including bla _NDM-1, bla _VIM-2, and bla _OXA-48. This study described the first emergence of NDM-1 producing Klebsiella oxytoca in Egyptian ICUs.

Conclusion

High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiotics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

Antimicrobial resistance, virulence factors, and genotypes of Pseudomonas aeruginosa clinical isolates from Gorgan, northern Iran

Pseudomonas aeruginosa is an important nosocomial pathogen with a capacity of resistance to multiple antibiotics and production of various extracellular and cell-associated virulence factors that clearly contribute to its pathogenicity. The objective of this study was to investigate the antibiotic susceptibility, virulence factors, and clonal relationship among clinical isolates of P. aeruginosa. Different clinical specimens from hospitalized patients were investigated for P. aeruginosa. Susceptibility of the isolates was evaluated by disc diffusion and broth microdilution methods, as described by the Clinical and Laboratory Standards Institute (CLSI) guideline. A total of 97 P. aeruginosa isolates were recovered from clinical specimens. The percentage of isolates resistant to antimicrobials was imipenem 25.77%, meropenem 15.46%, gentamicin 16.49%, tobramycin 15.46%, amikacin 16.49%, ciprofloxacin 20.61%, levofloxacin 24.74, ceftazidime 20.61%, piperacillin 15.46%, piperacillin/tazobactam 12.37%, colistin 9.27%, and polymyxin B 11.34%. Of isolates, 87.62% possessed β-hemolytic activity, 78.35% lecithinase, 59.8% elastase, 37.11% DNase, and 28.86% twitching motility. The frequency of virulence genes in isolates was lasB 82.47%, plcH 82.47%, exoA 58.76%, exoS 56.7%, and pilA 10.3%. ERIC-PCR typing clustered P. aeruginosa isolates to 19 common types (CT1-CT19) containing isolates from different hospitals and 43 single types (ST1-ST43). Colistin and polymyxin B were the most effective agents against the majority of P. aeruginosa isolates, emphasizing the effort to maintain their antibacterial activity as last-line therapy. The frequency of some virulence factors and genes was noticeably high, which is alarming. In addition, more effective strategies and surveillance are necessary to confine and prevent the inter-hospital and/or intra-hospital dissemination of P. aeruginosa between therapeutic centers.