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Evaluation of Chemical Changes in Laboratory-Induced Colistin-Resistant Klebsiella pneumoniae.

ABSTRACT: This study evaluates the electrical potential and chemical alterations in laboratory-induced colistin-resistant Klebsiella pneumoniae, as compared to the susceptible strain using spectroscopic analyses. The minimal inhibitory concentration (MIC) of colistin, ζ-potential and chemical composition analysis of K. pneumoniae strains are determined. The results obtained for the K. pneumoniae^Col-R with induced high-level colistin resistance (MIC = 16.0 ± 0.0 mg/L) are compared with the K. pneumoniae^Col-S strain susceptible to colistin (MIC = 0.25 ± 0.0 mg/L). Fourier transform infrared (FTIR) and Raman spectroscopic studies revealed differences in bacterial cell wall structures and lipopolysaccharide (LPS) of K. pneumoniae^Col-R and K. pneumoniae^Col-S strains. In the beginning, we assumed that the obtained results could relate to a negative charge of the bacterial surface and different electrostatic interactions with cationic antibiotic molecules, reducing the affinity of colistin and leading to its lower penetration into K. pneumoniae^Col-R cell. However, no significant differences in the ζ-potential between the K. pneumoniae^Col-R and K. pneumoniae^Col-S strains are noticed. In conclusion, this mechanism is most probably associated with recognisable changes in the chemical composition of the K. pneumoniae^Col-R cell wall (especially in LPS) when compared to the susceptible strain.

SUBMITTER: Pruss A

PROVIDER: S-EPMC8268070 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The emergence and dissemination of carbapenemases, bacterial enzymes able to inactivate most β-lactam antibiotics, in Enterobacteriaceae is of increasing concern. The concurrent spread of resistance against colistin, an antibiotic of last resort, further compounds this challenge further. Whole-genome sequencing (WGS) can play a significant role in the rapid and accurate detection/characterization of existing and emergent resistance determinants, an essential aspect of public health surveillance and response activities to combat the spread of antimicrobial resistant bacteria. In the current study, WGS data was used to characterize the genomic content of antimicrobial resistance genes, including those encoding carbapenemases, in 10 multidrug-resistant Klebsiella pneumoniae isolates from Pakistan. These clinical isolates represented five sequence types: ST11 (n = 3 isolates), ST14 (n = 3), ST15 (n = 1), ST101 (n = 2), and ST307 (n = 1). Resistance profiles against 25 clinically-relevant antimicrobials were determined by broth microdilution; resistant phenotypes were observed for at least 15 of the 25 antibiotics tested in all isolates except one. Specifically, 8/10 isolates were carbapenem-resistant and 7/10 isolates were colistin-resistant. The blaNDM-1 and blaOXA-48 carbapenemase genes were present in 7/10 and 5/10 isolates, respectively; including 2 isolates carrying both genes. No plasmid-mediated determinants for colistin resistance (e.g. mcr) were detected, but disruptions and mutations in chromosomal loci (i.e. mgrB and pmrB) previously reported to confer colistin resistance were observed. A blaOXA-48-carrying IncL/M-type plasmid was found in all blaOXA-48-positive isolates. The application of WGS to molecular epidemiology and surveillance studies, as exemplified here, will provide both a more complete understanding of the global distribution of MDR isolates and a robust surveillance tool useful for detecting emerging threats to public health.

Project description:Klebsiella pneumoniae is a nosocomial pathogen with high morbidity and mortality rates in hospitalized patients. The emergence of multidrug-resistant K. pneumoniae has become more challenging to treat, with the prevalence of colistin-resistance. Therefore, reliable methods for detecting colistin resistance are required. Many plants' essential oils have antimicrobial activity and have been used to combat multiple antibiotic resistances. This study aimed to investigate the characterization and prevalence of the colistin resistance gene mcr-1 in K. pneumoniae in Egypt, evaluate rapid polymyxin NP test, determine the transferability of mcr-1 gene, and study the synergistic activity of eugenol combined with colistin against K. pneumoniae isolates. Eighty-two K. pneumonia isolates were collected from different human samples, followed by antibiotic susceptibility testing, rapid polymyxin NP test, and detection of the mcr-1 gene and its transfer frequency. Determination of the MICs of colistin alone and in combination with eugenol was performed, then mcr-1 gene expression was determined in the presence of eugenol. Thirty-two isolates (39%) were colistin-resistant. Rapid polymyxin NP test failed to detect resistant isolates with MICs below 32 µg/mL. Detection of mcr-1 gene was made in 27 (84%) of colistin resistant isolates. The rest isolates possess alteration in the mgrB gene which probably causes colistin resistance. The mcr-1 gene was transferred by conjugation to other sensitive isolates. MIC of eugenol ranged from 416 to 1664 µg/mL, and FICI ranged from 0.265 to 0.75. Results also revealed suppression of mcr-1 gene expression in the presence of sub MIC of eugenol. Our results demonstrated a high prevalence of mcr-1 in Egypt and its ability to transfer to other strains. Difficult determination of colistin-resistant isolates with low values with rapid polymyxin NP test was apparent. Eugenol exerted a synergistic effect with colistin and improved its antimicrobial activity.

Project description:Objective: The emergence of resistance against last-resort antibiotics, carbapenem and colistin, in Klebsiella pneumoniae has been reported across the globe. Bacteriophage therapy seems to be one of the most promising alternatives. This study aimed to optimize the quantity and frequency of bacteriophage cocktail dosage/s required to eradicate the Klebsiella pneumoniae bacteria in immunocompetent septicemic mice. Methods: The three most active phages ɸKpBHU4, ɸKpBHU7, and ɸKpBHU14 characterized by molecular and TEM analyses were in the form of cocktail and was given intraperitoneally to mice after inducing the septicemia mice model with a constant dose of 8 × 107 colony-forming unit/mouse (CFU/mouse) Klebsiella pneumoniae. After that, the efficacy of the phage cocktail was analyzed at different dosages, that is, in increasing, variable, constant, and repeated dosages. Furthermore, interleukin-6 and endotoxin levels were estimated with variable doses of phage cocktail. Results: We have elucidated that phage therapy is effective against the Klebsiella pneumoniae septicemia mice model and is a promising alternative to antibiotic treatments. Our work delineates that a single dose of phage cocktail with 1 × 105 plaque-forming unit/mouse (PFU/mouse) protects the mice from fatal outcomes at any stage of septicemia. However, a higher phage dosage of 1 × 1012 PFU/mice is fatal when given at the early hours of septicemia, while this high dose is not fatal at the later stages of septicemia. Moreover, multiple repeated dosages are required to eradicate the bacteria from peripheral blood. In addition, the IL-6 levels in the 1 × 105 PFU/mouse group remain lower, but in the 1 × 1012 PFU/mouse group remains high at all points, which were associated with fatal outcomes. Conclusion: Our study showed that the optimized relatively lower and multiple dosages of phage cocktails with the strict monitoring of vitals in clinical settings might cure septicemia caused by MDR bacteria with different severity of infection.

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Evaluation of Chemical Changes in Laboratory-Induced Colistin-Resistant Klebsiella pneumoniae.

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