New Delhi Metallo-β-lactamase and other mechanisms of carbapenemases among Enterobacteriaceae in rural South India

Emergence of pandrug-resistant carbapenemase-producing Enterobacterales in dogs and cats: a cross-sectional study in Egypt

One of the most important emerging health problems is the increasing role of animals in the rapid global rise in resistance to last-resort antibiotics, such as carbapenems. However, there is limited information on the role of pet animals in harboring and spreading pandrug-resistant (PDR) carbapenemase-producing Enterobacterales (CPE), especially in Egypt. This cross-sectional study was conducted to screen for CPE in healthy and diseased pets using phenotypic and molecular methods and the NG-Test CARBA 5 immunochromatographic assay. Rectal swabs were collected from 62 dogs and 48 cats, incubated overnight in tryptic soy broth containing 10 μg of meropenem disc and subsequently cultured on MacConkey agar supplemented with meropenem (1 mg/L). Sixty-six isolates (60.6%), including 56 Klebsiella pneumoniae, seven Escherichia coli, and three K. oxytoca isolates, were confirmed to be carbapenem-resistant Enterobacterales (CRE) by the disc diffusion method, broth microdilution test, CNPt-direct, and PCR assay targeting carbapenemase genes. Forty-three (65.2%) dogs and 23 (34.8%) cats carried CPE. Of these, 35 (70.0%) were healthy (including 27 dogs and 8 cats) and 31 (52.5%) were diseased (including 16 dogs and 15 cats). bla OXA-181 was the most common gene detected (42/66, 63.6%), followed by bla IMP (40/66, 60.6%), bla OXA-48-like (29/66, 43.9%), bla KPC and bla VIM (20/66, 30.3% each), and bla NDM (17/66, 25.8%). The identified genotypes were bla KPC-2, bla IMP-1, bla VIM-1, bla NDM-1, and bla NDM-5. The CARBA 5 assay showed higher sensitivity and specificity for the detection of NDM, OXA and KPC than that for VIM and IMP genes. Antimicrobial resistance profiles of CRE isolates revealed 20 PDR, 30 extensively drug-resistant (XDR), and 16 multidrug-resistant (MDR) phenotypes. This study provides evidence of colonization with PDR CPE in dogs and cats. To manage the infection or colonization of pets in veterinary clinical settings, extended surveillance systems should be considered, and the use of critical antibiotics should be strictly controlled.

Ruthenium(II) polypyridyl complexes as emerging photosensitisers for antibacterial photodynamic therapy

Photodynamic therapy (PDT) has recently emerged as a potential valuable alternative to treat microbial infections. In PDT, singlet oxygen is generated in the presence of photosensitisers and oxygen under light irradiation of a specific wavelength, causing cytotoxic damage to bacteria. This review highlights different generations of photosensitisers and the common characteristics of ideal photosensitisers. It also focuses on the emergence of ruthenium and more specifically on Ru(II) polypyridyl complexes as metal-based photosensitisers used in antimicrobial photodynamic therapy (aPDT). Their photochemical and photophysical properties as well as structures are discussed while relating them to their phototoxicity. The use of Ru(II) complexes with recent advancements such as nanoformulations, combinatory therapy and photothermal therapy to improve on previous shortcomings of the complexes are outlined. Future perspectives of these complexes used in two-photon PDT, photoacoustic imaging and sonotherapy are also discussed. This review covers the literature published from 2017 to 2023.

Edwards M, Lennox A, Mahadevaiah S, Chandrashekhar S, Prudhvi Raj S, Pradhan A, Kalyatanda G. Prevalence of antimicrobial resistance in urine, blood, and wound pathogens among rural patients in Karnataka, India

Background and objective

Antimicrobial resistance (AMR) is increasing in tertiary-care hospitals across India, which consumes more antibiotics than any other country. Microorganisms with novel resistance mechanisms, initially isolated in India, are now recognized worldwide. Until now, most efforts to stem AMR in India have focused on the inpatient setting. Ministry of Health data now suggest that rural areas are playing a more significant role in the pathogenesis of AMR than was previously appreciated. Thus, we conducted this pilot study to ascertain whether AMR is common in pathogens causing infections acquired in the wider rural community.

Methods

We performed a retrospective prevalence survey of 100 urine, 102 wound, and 102 blood cultures obtained from patients who were admitted to a tertiary-care facility in Karnataka, India, with infections acquired in the community. The study population included patients >18 years of age who (1) were referred to the hospital by primary care doctors, (2) had a positive blood, urine, or wound culture, and (3) were not previously hospitalized. Bacterial identification and antimicrobial susceptibility testing (AST) were carried out on all isolates.

Results

Enterobacteriaceae were the most common pathogens isolated from urine and blood cultures. Significant resistance to quinolones, aminoglycosides, carbapenems, and cephalosporins was noted among pathogens isolated from all cultures. Specifically, high resistance rates (>45%) to quinolones, penicillin, and cephalosporins were evident among all 3 types of culture. Among blood and urinary pathogens, there were high resistance rates (>25%) to both aminoglycosides and carbapenems.

Conclusion

Efforts to stem AMR rates in India need to focus on rural populations. Such efforts will need to characterize antimicrobial overprescribing practices, healthcare-seeking behaviors, and antimicrobial use in agriculture in rural settings.

Evaluation of in-vitro susceptibility of ß-lactam-resistant Gram-negative bacilli to ceftazidime-avibactam and ceftolozane-tazobactam from clinical samples of a general hospital in southern Brazil

BACKGROUND

The spread of carbapenemase- and extended-spectrum β-lactamase (ESBL)-producing gram-negative bacilli (GNB) represent a global public health threat that limits therapeutic options for hospitalized patients. This study aimed to evaluate the in-vitro susceptibility of β-lactam-resistant GNB to ceftazidime-avibactam (C/A) and ceftolozane-tazobactam (C/T), and investigate the molecular determinants of resistance.

METHODS

Overall, 101 clinical isolates of Enterobacterales and Pseudomonas aeruginosa collected from a general hospital in Brazil were analyzed. Susceptibility to the antimicrobial agents was evaluated using an automated method, and the minimum inhibitory concentrations (MIC50/90) of C/A and C/T were determined using Etest®. The β-lactamase-encoding genes were investigated using polymerase chain reaction.

RESULTS

High susceptibility to C/A and C/T was observed among ESBL-producing Enterobacterales (100% and 97.3% for CLSI and 83.8% for BRCAST, respectively) and carbapenem-resistant P. aeruginosa (92.3% and 87.2%, respectively). Carbapenemase-producing Klebsiella pneumoniae exhibited high resistance to C/T (80%- CLSI or 100%- BRCAST) but high susceptibility to C/A (93.4%). All carbapenem-resistant K. pneumoniae isolates were susceptible to C/A, whereas only one isolate was susceptible to C/T. Both antimicrobials were inactive against metallo-β-lactamase-producing K. pneumoniae isolates. Resistance genes were concomitantly identified in 44 (44.9%) isolates, with bla CTX-M and bla SHV being the most common.

CONCLUSIONS

C/A and C/T were active against microorganisms with β-lactam-resistant phenotypes, except when resistance was mediated by metallo-β-lactamases. Most C/A- and C/T-resistant isolates concomitantly carried two or more β-lactamase-encoding genes (62.5% and 77.4%, respectively).

High Frequency of blaOXA-48like Producing Klebsiella pneumoniae Isolated from Nosocomial Infection in Azerbaijan, Iran

BACKGROUND

Klebsiella pneumoniae is one of the significant agents of hospital-acquired infections. In recent years, carbapenem-resistant K. pneumoniae (CRKP) isolates have been found in numerous epidemics of nosocomial infections. This study aimed to determine carbapenem resistance mechanisms and molecular epidemiological of CRKP infections in Azerbaijan, Iran.

MATERIALS AND METHODS

A total of 50 non-duplicated CRKP from January 2020 to December 2020 were isolated form Sina and Imam Reza Hospitals in Tabriz, Iran. Antimicrobial susceptibility testing was performed by the disk-diffusion method. The carbapenem resistance mechanisms were determined by the phenotypic and PCR procedures. CRKP isolates were typed by the Random Amplified Polymorphic DNA PCR (RAPD-PCR) technique.

RESULTS

Amikacin was the most effective antibiotics against CRKP isolates. AmpC overproduction was observed in five CRKP isolates. Efflux pump activity was found in one isolate by the phenotypic method. Carba NP test could find carbapenemases genes in 96% of isolates. The most common carbapenemases gene in CRKP isolates were bla_OXA-48-like (76%) followed by bla_NDM (50%), bla_IMP (22%), bla_VIM (10%), and bla_KPC (10%). The outer membrane protein genes (OmpK36 and OmpK35) were identified in 76% and 82% of CRKP isolates, respectively. RAPD-PCR analysis yielded 37 distinct RAPD-types. Most bla_OXA-48-like positive CRKP isolates were obtained from patients hospitalized in intensive care unit (ICU) wards with urinary tract infections.

CONCLUSION

The bla_OXA-48-like is the main carbapenemase among CRKP isolates in this area. Most bla_OXA-48-like producer CRKP strains were collected from the ICU ward and urine samples. To control infections due to CRKP, a strict control program in hospital settings is required.

Multiplex PCR Detection of Common Carbapenemase Genes and Identification of Clinically Relevant Escherichia coli and Klebsiella pneumoniae Complex

Carbapenem-resistant Enterobacterales (CRE) species are top priority pathogens according to the World Health Organization. Rapid detection is necessary and useful for their surveillance and control globally. This study developed a multiplex polymerase chain reaction (mPCR) detection of the common carbapenemase genes NDM, KPC, and OXA-48-like, together with identification of Escherichia coli, and distinguished a Klebsiella pneumoniae complex to be K. pneumoniae, K. quasipneumoniae, and K. variicola. Of 840 target Enterobacterales species, 190 E. coli, 598 K. pneumoniae, 28 K. quasipneumoniae, and 23 K. variicola. with and without NDM, KPC, or OXA-48-like were correctly detected for their species and carbapenemase genes. In contrast, for the Enterobacterales species other than E. coli or K. pneumoniae complex with carbapenemase genes, the mPCR assay could detect only NDM, KPC, or OXA-48-like. This PCR method should be useful in clinical microbiology laboratories requiring rapid detection of CRE for epidemiological investigation and for tracking the trends of carbapenemase gene dynamics.

Comparative evaluation of phenotypic and genotypic methods for the rapid and cost-effective detection of carbapenemases in extensively drug resistant Klebsiella pneumoniae

PURPOSE

Carbapenemases are the enzymes that can hydrolyze carbapenems and other β-lactam antibiotics. These enzymes confer resistance to multiple antibiotics and act as a stumbling block in the treatment of infections caused by gram-negative bacteria. Therefore, rapid and specific detection of these enzymes is crucial for deciding the course of treatment and better clinical outcomes.

MATERIAL AND METHODS

This study was conducted to compare various phenotypic and PCR based methods for the detection of carbapenemases in carbapenem- and colistin-resistant Klebsiella pneumoniae. One hundred clinical isolates of extensively resistant Klebsiella pneumoniae were included in the study. Phenotypic detection for carbapenemases was performed by Rapidec® Carba NP (Biomerieux), modified carbapenem inactivation method (mCIM), imipenem-ethylenediaminetetraacetic acid disk synergy (EDS), double disk synergy test using mercaptopropionic acid (DDST-MPA), and combined disk method (CD) and for colistin by microbroth dilution method. Genotypic detection for carbapenemases and colistin resistance was performed by targeted PCR.

RESULTS

The sensitivity of Carba NP test and mCIM were positive in 95% and 96% respectively and specificity was 100% for both methods. The sensitivity of EDS, DDST-MPA, and CD were 55.6%, 88.9% and 54.5% respectively. Among the carbapenem resistance genes, blaOXA-48 (82%) genes were the most prevalent. Among metallo-beta lactamases, blaVIM (56%) was most common followed by blaNDM (54%) and blaIMP (20%). The mcr-1 gene for colistin resistance was not detected in any isolate.

CONCLUSION

Among the five phenotypic assays analyzed, the mCIM is the most simple, inexpensive, accurate and reproducible method for carbapenemase detection in Klebsiella pneumoniae. The DDST-MPA test provides the best sensitivity for the detection of carbapenemases, although specificity is low. These tests, when applied in a clinical laboratory and assessed by the microbiologist, can help in guiding the course of treatment.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

Evaluation of Resistance Mechanisms in Carbapenem-Resistant Enterobacteriaceae

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) is a major concern leading to morbidity and mortality in the world. CRE often is becoming a cause of therapeutic failure in both hospital and community-acquired infections.

AIM

This study aimed to investigate the resistance mechanisms of CRE by phenotypic and molecular methods.

MATERIALS AND METHODS

Sixty CRE (50 Klebsiella pneumoniae, 6 Escherichia coli, and 4 Enterobacter spp.) were isolated from October 2018 to June 2019. Antimicrobial susceptibility testing was carried out using phenotypic methods. The carbapenem resistance mechanisms including efflux pump hyperexpression, AmpC overproduction, carbapenemase genes, and deficiency in OmpK35 and OmpK36 were determined by phenotypic and molecular methods, respectively.

RESULTS

Sixty CRE (50 Klebsiella pneumoniae, 6 Escherichia coli, and 4 Enterobacter spp.) were isolated from October 2018 to June 2019. Amikacin was found to be the most effective drug against CRE isolates. All isolates were resistant to imipenem and meropenem by the micro-broth dilution. AmpC overproduction was observed in all Enterobacter spp. and three K. pneumoniae isolates. No efflux pump activity was found. Carba NP test and Modified Hodge Test could find carbapenemase in 59 (98%) isolates and 57 (95%) isolates, respectively. The most common carbapenemase gene was bla OXA-48-like (72.8%) followed by bla NDM (50.8%), bla IMP (18.6%), bla VIM (11.8%), and bla KPC (6.7%). The ompK35 and ompK36 genes were not detected in 10 and 7 K. pneumoniae isolates, respectively.

CONCLUSION

The amikacin is considered as a very efficient antibiotic for the treatment of CRE isolates in our region. Carbapenemase production and overproduction of AmpC are the main carbapenem resistance mechanisms in CRE isolates. Finally, Carba NP test is a rapid and reliable test for early detection of carbapenemase-producing isolates.