Conjugative plasmidic AmpC detected in Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae human clinical isolates from Portugal

Calcium-sensing receptor alleviates gut damage caused by endotoxemia by regulating gut microbiota

Background

Growing evidence points to an association between the gut microbiota and neonatal diseases. Calcium-sensing receptor (CaSR) is a major modulator of tissue responses associated with calcium homeostasis and is highly expressed in the mammalian gut. CaSR may affect the composition and balance of the intestinal microenvironment.

Methods

Neonatal rats were randomized to the control, lipopolysaccharide (LPS), CaSR agonist, and CaSR inhibitor groups. The intestinal contents of neonatal rats were collected within 24 hours or 7 days after intervention. Then, 16S rRNA short amplicon sequencing was used to analyze biological information and the richness and diversity of individual taxa.

Results

LPS aggravated intestinal injury. The CaSR agonist alleviated injury, and the inhibitor further enhance intestinal injury. Activation of CaSR enhanced the diversity of the gut microbiota and the abundance of Lactobacillus. The lowest abundance of Firmicutes and the highest abundance of Bacteroidetes were found in the agonist group. CaSR impacted the bacterial species in rats with endotoxemia, and Akkermansia had the greatest effect on the differences among groups.

Conclusions

Activation of CaSRs could enhance the species richness and β-diversity of the gut microbiota and alter the abundance of many taxa. This could attenuate LPS-induced gut injury by modulating the gut microbiota.

Phenotypic and genetic screening of Klebsiella pneumoniae isolates from human UTI patients for beta-lactamases and their genetic diversity analysis by ERIC and REP PCRs

Klebsiella pneumoniae is one of the major nosocomial pathogens responsible for pneumoniae, septicaemia, liver abscesses, and urinary tract infections. Coordinated efforts by antibiotic stewardship and clinicians are underway to curtail the emergence of antibiotic-resistant strains. The objective of the present study is to characterize K. pneumoniae strains through antibiotic resistance screening for production of beta-lactamases (β-lactamases) such as extended spectrum beta lactamases (ESBLs), AmpC β-lactamases, and carbapenemases by phenotypic and genotypic methods and genetic fingerprinting by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) and repetitive element palindromic PCR (REP-PCR). A total of 85 K. pneumoniae strains isolated from 504 human urinary tract infections (UTI) were used in this study. Only 76 isolates showed positive in phenotypic screening test (PST), while combination disc method (CDM) as phenotypic confirmatory test (PCT) confirmed 72 isolates as ESBL producers. One or more β-lactamase genes were detected by PCR in 66 isolates (91.66%, 66/72) with blaTEM gene being the most predominant (75.75%, 50/66). AmpC genes could be detected in 21 isolates (31.8%, 21/66) with FOX gene being the predominant (24.24%, 16/66), whereas NDM-I was detected in a single strain (1.51%, 1/66). Genetic fingerprinting using ERIC-PCR and REP-PCR revealed wide heterogeneity among β-lactamase producing isolates with discriminatory power of 0.9995 and 1, respectively.

Plasmid-Mediated AmpC (pAmpC) Genotypes Among Uropathogenic Escherichia coli: A Hospital-Based Study From Western Uttar Pradesh

Introduction Resistance due to AmpC and extended-spectrum beta (β)-lactamases (ESBLs) in Escherichia coli is an emerging problem worldwide. AmpC enzymes are a subclass of β-lactamases that have a capacity to hydrolyze and deactivate a large range of β-lactam antibiotics, particularly cephalosporins, penicillins, and monobactams, although frequently being susceptible to carbapenems and fourth-generation cephalosporins. The prevalence of plasmid-mediated AmpC (pAmpC) genotypes in uropathogenic E. coli isolates were looked at a tertiary care teaching hospital of Western Uttar Pradesh. Materials and methods A total of 312 non-repeat clinical E. coli isolates among patients presented with urinary tract infections (UTIs) were investigated by standard microbiological methods. Isolates were screened for the presence of ampC using a cefoxitin (30 µg) disc and confirmed using an inhibitor-based assay. Using multiplex polymerase chain reaction (PCR), six AmpC genotypes, namely, CIT, DHA, EBC, ACC, FOX, and MOX, were genotypically identified. Results A total of 152 (48.72%) uropathogenic E. coli isolates tested positive on the cefoxitin screening. Out of which, AmpC production was confirmed in 118/152 (77.63%) using a phenotypic method. In particular, the pAmpC gene was found in 56/152 (36.84%) isolates. CIT was the most common gene detected in this geographical area (57.14 %). Multiple genes, i.e., CIT and FOX, were also detected in 14.29% of the isolates.  Conclusion Identifying AmpC producers is important in routine microbiology laboratory as they are a nosocomial threat requiring strict adherence to infection control protocols. A confirmatory phenotypic test followed by genotypic tests will help in the correct and accurate identification of this resistance.

Synthesis and photodynamic antimicrobial chemotherapy against multi-drug resistant Proteus mirabilis of ornithine-porphyrin conjugates in vitro and in vivo

For the treatment of bacterial infections, photodynamic antimicrobial chemotherapy (PACT) has the advantage of circumventing multi-drug resistance. In this work, new cationic photosensitizers against multi-drug resistant Proteus mirabilis (MRPM) were designed and synthesized by the conjugation of amino phenyl porphyrin with basic amino acid L-ornithine. Their photoinactivation efficacies against MRPM in vitro were reported and include the influence of laser energy, uptake, MIC and MBC, dose-dependent photoinactivation effects, membrane integrity, and fluorescence imaging. The PACT in vivo was evaluated using a wound mouse model infected by MRPM. Photosensitizer 4d displayed high photo inactivation efficacy against MRPM at 7.81 μM under illumination, and it could accelerate wound healing via bactericidal effect. These ornithine-porphyrin conjugates are potential photosensitizers for PACT in the treatment of MRPM infection.

Prevalence of plasmid-mediated AmpC β-lactamases among uropathogenic Escherichia coli isolates in southwestern Iran

OBJECTIVE

This study was undertaken to evaluate AmpC β-lactamase-producing Escherichia coli urine isolates and to characterize the frequency of plasmid-mediated AmpC (pAmpC)-encoding genes.

METHODS

Antimicrobial susceptibility tests were performed using the disk diffusion technique. AmpC β-lactamase production was assessed with a phenotypic inhibitor-based method. The presence of 6 pAmpC-encoding cluster genes was detected by multiplex polymerase chain reaction (PCR).

RESULTS

The proportion of antibiotic resistance of E. coli isolates ranged from 7.4% to 90.5%, and more than half (51.6%) of the total isolates were multidrug-resistant (MDR). Among the 95 E. coli isolates, 60 (63.2%) were found to be cefoxitin-resistant, but only 14 (14.7%) isolates were confirmed as AmpC β-lactamase-producers. In the PCR assay, pAmpC-encoding genes were found in 15 (15.8%) isolates, and blaDHA was the most prevalent type. However, blaFOX, blaMOX, and blaACC genes were not detected in the isolates.

CONCLUSION

Our findings contributed valuable information concerning antibiotic resistance, confirmatory phenotypic testing for AmpC production, and pAmpC β-lactamase gene content in E. coli isolates in southwestern Iran. The level of MDR recorded in AmpC-producing strains of this study was worrying; therefore, implementing strong infection control approaches to reduce the MDR burden is recommended.