Characterization of KPC-2-producing Klebsiella pneumoniae and affected patients of a pediatric hospital in Brazil

Carbapenemase-producing Klebsiella pneumoniae (CPKp) infections are important threats to pediatric populations. Thus, a retrospective study was conducted in a Brazilian reference pediatric hospital, and 26 CPKp isolates obtained from 23 patients were characterized. The affected population had important underlying diseases, reflecting previous hospitalization and antibiotic use. Most CPKp isolates were resistant to all antibiotic classes, and bla_KPC-2 was the only carbapenemase-encoding gene. bla_CTX-M-15 was common among the isolates, and modification or absence of the mgrB gene was the cause of polymyxin B resistance. Ten different sequence types were identified, and clonal complex 258 was prevalent. Alleles wzi50 and wzi64 were the most recurrent ones regarding K-locus type, with a remarkable contribution of the epidemic ST11/KL64 lineage as a colonizer. Our findings show that lineages associated with the pediatric population are similar to those found in adults, reinforcing the need for epidemiological surveillance to effectively implement prevention and control measures.

The Association of the Phylogenetic Typing of the Klebsiella pneumoniae Isolates with Antibiotic Resistance

Klebsiella pneumoniae complex (KPC) accounts for approximately one-third of all Gram-negative infections. Moreover, it is highly resistant and can taxonomically be distributed into KpI, KpII, and KpIII phylogroups. This study aimed to investigate the distribution of phylogenetic groups and the relationship between them and antibiotic resistance patterns. For this purpose, we collected KPC isolates from Tabriz, Iran, between 2018 and 2020. Antimicrobial susceptibility testing was performed by disk diffusion agar, and phylogenetic groups were then examined using gyrA restriction fragment length polymorphism (RFLP) and parC PCR methods. A total of 100 KPC isolates were obtained from the clinical specimens (urine, respiratory secretion, blood, wounds, and trachea). The enrolled patients included 47 men and 53 women aged from 1 to 91 years old. The highest sensitivity was found related to fosfomycin as 85%, followed by amikacin as 66%. The three phylogenetically groups by the RFLP-PCR method were found in KPC, 96% (96 isolates) as KpI, 3% (3 isolates) as KpII, and 1% (1isolate) as KpIII. The highest antibiotic resistance was observed in KpI. It was shown that a valid identification of three phylogenetic groups of KPC can be done by combining both gyrA PCR-RFLP and parC PCR. Of note, the KpI group was also observed as the dominant phylogenetic group with the highest resistance to antibiotics.

Molecular Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates Producing blaVIM, blaNDM, and blaIMP in Clinical Centers in Isfahan, Iran

Background: The emergence and spread of metallo-beta-lactamase (MBL)-producing Klebsiella pneumoniae are growing global public health concerns. One of the most common mechanisms of carbapenem resistance is the production of MBLs, including Verona integron-encoded metallo-beta-lactamase (VIM), New Delhi metallo-beta-lactamase (NDM) and imipenemase (IMP). Objectives: This study aimed to investigate MBLs production among K. pneumoniae isolates. Methods: In this study, 240 K. pneumoniae isolates were collected from clinical samples in three clinical centers of Isfahan, Iran, during February 2017 and November 2018. All isolates were identified using biochemical, microbiological, and molecular methods, and then antimicrobial susceptibility tests were performed to find MBL-producing isolates via phenotypic and genotypic detection methods. Moreover, the minimum inhibitory concentration (MIC) of antibiotics against MBL-positive strains was determined by E-test. Eventually, the clonal relatedness of the MBL-positive strains was analyzed using both multilocus sequence typing (MLST) and rep-PCR. Results: Overall, 33.7% (81/240) of the isolates were resistant to carbapenems, among which 25 (30.8%) were considered MBL-positive. Among 81 strains resistant to carbapenems, genes encoding FimH, rmpA, and mrkD were detected in 87.6% (71/81), 11.1% (9/81), and 67.9% (55/81) of the isolates, respectively. Besides, TEM and SHV as antibiotic resistance genes were detected in 49.3% (40/81) and 80.2% (65/81) of the isolates. But, magA was not detected in any of the tested isolates. The PCR results revealed that blaVIM-1 was the most prevalent gene (13.6%; 11/81), while both blaIMP-1 and blaNDM-1 were only detected in two isolates. Multilocus sequence typing demonstrated that 15 MBL producers belonged to three sequence types (ST): 11 to ST23, two to ST1147, and two to ST15. Finally, rep-PCR typing showed similar fingerprints with MLST, except for ST23, such that ST23 was discriminated in two clonal groups, suggesting the greater discriminatory power of rep-PCR. Conclusions: Here, we reported the emergence of MBL-producing K. pneumoniae in clinical centers of Isfahan, Iran. The findings are alarming and represent the urgent need for the application of infection control programs.

Galactose-Clicked Curcumin-Mediated Reversal of Meropenem Resistance among Klebsiella pneumoniae by Targeting Its Carbapenemases and the AcrAB-TolC Efflux System

In over eighty years, despite successive antibiotics discoveries, the rapid advent of multidrug resistance among bacterial pathogens has jolted our misapprehension of success over them. Resistance is spreading faster than the discovery of new antibiotics/antimicrobials. Therefore, the search for better antimicrobials/additives becomes prudent. A water-soluble curcumin derivative (Curaq) was synthesised, employing a Cu (I) catalysed 1, 3-cyclo addition reaction; it has been evaluated as a potential treatment for multidrug-resistant isolates and as an antibiotic adjuvant for meropenem against hypervirulent multidrug-resistant Klebsiella pneumoniae isolates. We also investigated its solubility and effect over carbapenemase activity. Additionally, we investigated its impact on the AcrAB-TolC system. We found that Curaq inhibited bacterial growth at a minimal concentration of 16 µg/mL; at a 32 µg/mL concentration, it killed bacterial growth completely. Only nine (9.4%) Klebsiella isolates were sensitive to meropenem; however, after synergising with Curaq (8 µg/mL), 85 (88.54%) hvKP isolates became sensitive to the drug. The Curaq also inhibited the AcrAB-TolC efflux system at 1 µg/mL concentration by disrupting the membrane potential and causing depolarisation. The kinetic parameters obtained also indicated its promise as a carbapenemase inhibitor. These results suggest that Curaq can be an excellent drug candidate as a broad-spectrum antibacterial and anti-efflux agent.

The Efficacy of AgNO3 Nanoparticles Alone and Conjugated with Imipenem for Combating Extensively Drug-Resistant Pseudomonas aeruginosa

INTRODUCTION

The extensive drug-resistant (XDR) Pseudomonas aeruginosa (P. aeruginosa) causes a range of infections with high mortality rate, which inflicts additional costs on treatment. The use of nano-biotechnology-based methods in medicine has opened a new perspective against drug-resistant bacteria. The aim of this study was to evaluate the effectiveness of the AgNO3 nanoparticles alone and conjugated with imipenem (IMI) to combat extensively drug-resistant P. aeruginosa.

METHODS

Antibiotic susceptibility was carried out using disc diffusion method. Detection of different resistant genes was performed using standard polymerase chain reaction (PCR). The chemically synthesized AgNO3 particles were characterized using scanning electron microscope (SEM), dynamic light scattering (DLS) and X-ray diffraction (XRD) methods. Fourier transform infrared spectroscopy (FTIR) was accomplished to confirm the binding of AgNO3 with IMI. The microdilution broth method was used to obtain minimum inhibitory concentration (MIC) of AgNO3 and IMI-conjugated AgNO3. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was carried out on L929 cell line to study the cytotoxicity of nanoparticles. The data were analyzed by Eta correlation ratio and chi-square (X 2) test.

RESULTS

Analysis of the antibiotic resistance pattern showed that 12 (24%) isolates were XDR, and MIC values of IMI were between 64 and 128 μg/mL. Frequency of SHV, TEM, CTX M, IMP, VIM, OPR, SIM, SPM, GIM, NDM, VEB, PER, KPC, OXA, intI, intII, and intIII genes were 29 (58%), 26 (52%), 26 (52%), 32 (64%), 23 (46%), 43 (86%), 3 (6%), 6 (12%), 3 (6%), 4 (8%), 7 (14%), 6 (12%), 18 (36%), 4 (8%), 19 (38%), 16 (32%), and 2 (4%), respectively. The XRD, SEM, DLS, and FTIR analysis confirmed the synthesis of AgNO3 nanoparticles and their conjugation with IMI. The AgNO3 nanoparticles had antimicrobial activity, and their conjugation with IMI showed enhanced effectiveness against XDR isolates. The synthesized AgNO3 showed no cytotoxic effects.

CONCLUSION

The results suggest that IMI-conjugated AgNO3 has a strong potency as a powerful antibacterial agent against XDR P. aeruginosa.

Determination of the frequency of β-lactamase genes (bla SHV, bla TEM, bla CTX-M) and phylogenetic groups among ESBL-producing uropathogenic Escherichia coli isolated from outpatients

Background

Escherichia coli accounts for 70–95% of community-acquired urinary tract infections (UTIs). Recently, there has been an increase in the prevalence of extended-spectrum β-lactamase (ESBL) in the community which required an accurate identification for better management. Therefore, the current study was performed to determine the antimicrobial resistance pattern, investigate ESBL phenotypes and genotypes (blaCTX-M, bla TEM and bla SHV genes) and determine the phylogenetic groups among ESBL-positive isolates from outpatients.

Methods

One hundred and eighty-three positive urine samples were collected from 4450 outpatient clinic attendees. Antibiotic susceptibility was determined and ESBL phenotype screening was carried out using disk diffusion agar and combination disk techniques, respectively. The assessment of the presence of the blaCTX-M, bla TEM and blaSHV genes and phylogenetic grouping were performed using the polymerase chain reaction (PCR) method.

Results

Out of 183 E. coli isolates, 59 (32.2%) showed a positive ESBL phenotype. The prevalence of ESBL-producing E. coli was higher in males (57.4%). Fifty-seven of the ESBL-producing strains carried at least one of the β-lactamase genes (bla CTX-M, bla TEM, bla SHV). Phylotyping of multi-drug resistant isolates indicated that the isolates belonged to B2, A and D phylogroups. Analysis of resistance patterns among these phylogroups revealed that 74.4%, 55.3% and 29.7% of the isolates in the B2 group were resistant to trimethoprim-sulfamethoxazole, ciprofloxacin and gentamicin, respectively. Most of the strains in the phylogroup B2 carried the bla CTX-M gene.

Conclusions

All the ESBL-producing isolates were placed in one of the four phylogenetic groups. The presence of CTX-M and resistance to quinolones were more frequent in B2 strains than in non-B2 strains.