The effect of Zinc Oxide nanoparticles on Pseudomonas aeruginosa biofilm formation and virulence genes expression.

INTRODUCTION: Due to increased resistance to antimicrobial agents, infectious diseases remain a public health problem worldwide. The current study was designed to examine the effect of Zinc Oxide nanoparticles (ZnO-np) against the biofilm formation ability of P. aeruginosa clinical isolates and to study its effect on the expression level of the genes involved in biofilm formation and virulence factors production. METHODOLOGY: The MIC of ZnO-np against P. aeruginosa was determined by the broth micro dilution method. The effect of ZnO-np on the biofilm-forming isolates of P. aeruginosa was monitored by the microtiter plate method. P. aeruginosa isolates were tested for the expression of different biofilm and virulence genes using real-time rt-PCR. RESULTS: ZnO-np significantly down-regulated the expression level of all biofilm and virulence genes of P. aeruginosa clinical isolates except the toxA gene. CONCLUSIONS: This study demonstrates the promising use of ZnO-np as an anti-biofilm and anti-virulence compound.

Prevalence, phylogeny, and antimicrobial resistance of Escherichia coli pathotypes isolated from children less than 5 years old with community acquired- diarrhea in Upper Egypt.

BACKGROUND: Diarrhoea, affecting children in developing countries, is mainly caused by diarrheagenic Escherichia coli (DEC). This study principally aimed to determine the prevalence of DEC pathotypes and Extended-spectrum ß-lactamase (ESBL) genes isolated from children under 5 years old with diarrhea. METHODS: A total of 320 diarrhoea stool samples were investigated. E. coli isolates were investigated for genes specific for enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) and enterohemorrhagic E. coli (EHEC) using polymerase chain reaction (PCR). Furthermore, antimicrobial susceptibility testing, detection of antibiotic resistance-genes and phylogenetic typing were performed. RESULTS: Over all, DEC were isolated from 66/320 (20.6%) of the children with diarrhoea. EAEC was the predominant (47%), followed by typical EPEC (28.8%) and atypical EPEC (16.6%). Co-infection by EPEC and EAEC was detected in (7.6%) of isolates. However, ETEC, EIEC and EHEC were not detected. Phylogroup A (47%) and B2 (43.9%) were the predominant types. Multidrug-resistance (MDR) was found in 55% of DEC isolates. Extended-spectrum ß-lactamase (ESBL) genes were detected in 24 isolates (24 blaTEM and 15 blaCTX-M-15). Only one isolate harbored AmpC ß-lactamase gene (DHA gene). CONCLUSION: The study concluded that, EAEC and EPEC are important causative agents of diarrhoea in children under 5 years. MDR among DEC has the potential to be a big concern.

Prevalence and molecular characteristics of ESBL and AmpC ß -lactamase producing Enterobacteriaceae strains isolated from UTIs in Egypt.

BACKGROUND: Infections caused by Enterobacteriaceae are mainly treated with the ß-lactam antibiotics, nevertheless, the emergence of species with plasmid-borne ß-lactamases has decreased the efficacy of these antibiotics. Therefore, continuing studies on the resistance pattern of different regions is important for assessment of proper antimicrobial therapy protocols. The study aimed to characterize extended-spectrum ß-lactamase (ESBL) and AmpC ß -lactamase (AmpC) producing Enterobacteriaceae isolated from community-acquired UTIs in Egypt. METHODS: Out of 705 urine samples, 440 Enterobacteriaceae isolates were investigated to detect ESBL and AmpC ß -lactamases producers by phenotypic and molecular methods. RESULTS: Out of 440 Enterobacteriaceae isolates, 311 were identified as ESBL producers by phenotypic testing. ESBL genes were detected in 308 isolates. BlaCTX-M-type was the most prevalent 254 (81.6%), out of them blaCTXM-15 was the commonest (152, 48.8%) followed by blaCTX-M-1 (140, 45%), blaCTX-M-8 (72, 23.1%) and lastly blaCTX-M-2 (4, 1.3%). blaTEM gene also was detected in a high rate (189, 60.7%). Two hundred and thirty-five (75.5%) of ESBL producers harbored blaCTX-M in combination with blaTEM and/or blaSHV genes. Multiple drug resistance in the ESBL-producers was significantly (P < 0.05) higher than in non-ESBL producers. Imipenem was the most effective drug against ESBL producers. Among 35 cefoxitin resistant isolates, 18 (51.4%) identified as carrying AmpC genes by multiplex PCR. Within AmpC ß -lactamase genes, DHA gene was the predominant gene (15, 42.3%). CIT and MOX genes were also present, but in a low rate (5, 14.2% and 4, 11.4%) respectively. Co-existence of multiple AmpC genes was detected exclusively in K. pneumoniae isolates. E. coli isolates harbored DHA gene only. However, FOX gene was not detected in the study isolates. Seventeen of isolates carrying AmpC genes were also positive for ESBL genes. CONCLUSION: The study shows that the prevalence of ESBL producing Enterobacteriaceae spread in south Egypt is alarming, however AmpC ß -lactamase production is not so high.

Phylogenic classification and virulence genes profiles of uropathogenic E. coli and diarrhegenic E. coli strains isolated from community acquired infections.

The emergence of E.coli strains displaying patterns of virulence genes from different pathotypes shows that the current classification of E.coli pathotypes may be not enough, the study aimed to compare the phylogenetic groups and urovirulence genes of uropathogenic Escherichia coli (UPEC) and diarrheagenic E.coli (DEC) strains to extend the knowledge of E.coli classification into different pathotypes. A total of 173 UPEC and DEC strains were examined for phylogenetic typing and urovirulence genes by PCR amplifications. In contrast to most reports, phylogenetic group A was the most prevalent in both UPEC and DEC strains, followed by B2 group. Amplification assays revealed that 89.32% and 94.29% of UPEC and DEC strains, respectively, carried at least one of the urovirulence genes, 49.5% and 31.4% of UPEC and DEC strains, respectively, carried ≥ 2 of the urovirulence genes, fim H gene was the most prevalent (66.9% and 91.4%) in UPEC and DEC strains respectively. Twenty different patterns of virulence genes were identified in UPEC while 5 different patterns in DEC strains. Strains with combined virulence patterns of four or five genes were belonged to phylogenetic group B2. Our finding showed a closer relationship between the DEC and UPEC, so raised the suggestion that some DEC strains might be potential uropathogens. These findings also provide different insights into the phylogenetic classification of E. coli as pathogenic or commensals where group A can be an important pathogenic type as well as into the classification as intestinal or extra- intestinal virulence factors.