Prevalence of Enterobacteriaceae spp. and its multidrug-resistant rates in clinical isolates: A two-center cross-sectional study.

Enterobacteriaceae spp., owing to their high durability and antibiotic-resistant mechanisms, are described as an eminent part of health treatments in hospital-acquired infections. This study aimed to estimate the prevalence of clinical isolated Enterobacteriaceae spp., and their multidrug-resistant rate in the north of Iran. In this cross-sectional study, over two years (2017-2019), clinical isolates were collected and Enterobacteriaceae spp. were identified using the standard media culture and Analytical Profile Index (API 20E) kit from two centers in the north of Iran. Isolates were confirmed by targeting the rpoB gene. Moreover, the susceptibility patterns of isolates were assessed using disc diffusion methods according to the Clinical Laboratory Standard Institute (CLSI) guidelines. Out of 2645 clinical specimens, 297 (11.2%) were confirmed as Enterobacteriaceae spp. containing Eshershia. coli 93 (31%), Citrobacter freundii 65 (21.9%), Klebsiella pneumoniae 48 (16.2%), Enterobacter spp. 43 (14.5%), and Proteus spp. 23 (7.7%). As much as 8.7% of other spp. Ampicillin (81.1%) and cephalexin (80.9%) have been shown to have the greatest resistant, and nalidixic acid (65%) and amikacin (59.2%) were the most sensitive drugs. Multidrug-resistance (MDR) strains are more isolated in the Burn and Burn intensive care unit (BICU) than other wards. The MDR frequency in Bouali and Zareh hospitals were 65 (49.61%) and 130 (78.31%), respectively. Considering the high isolation rates of MDR Enterobacteriaceae spp., preventive measures need to be taken to remove the mentioned bacteria from hospital wards.

Purification and Evaluation of Polysaccharide Intercellular Adhesion (PIA) Antigen from Staphylococcus epidermidis.

The polysaccharide intercellular adhesin (PIA) confers major functional effects in biofilm formation, which bears an important role in the pathogenicity of Staphylococcus epidermidis. Following the identification of biofilm-forming strains by biochemical and molecular methods, isogenic strain was prepared and in vitro biofilm formation assay was performed consequently. By parallel analysis of both the PIA-positive and PIA-negative strains using size exclusion chromatography by Fast protein liquid chromatography (FPLC) method, the respective PIA was purified. Recovered PIA was examined using colorimetric and hemagglutination assays. Finally, the recovered PIA was analyzed using Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy methods. By the parallel purification process and comparison of the obtained graphs from the FPLC detector, fractions near the void volume were determined as PIA. The colorimetric and hemagglutination assays were applied and the content of carbohydrates (hexose = 620 µg/ml, hexosamine = 5700 µg/ml and ketoses = 170 µg/ml) and hemagglutination titer (1:128) in recovered polysaccharide were determined. This study shows that PIA has a significant role in the biofilm formation in S. epidermidis strains. The recovered polysaccharide and its molecular weight were analyzed within the near void volume of the utilized column.

PIA and rSesC Mixture Arisen Antibodies Could Inhibit the Biofilm-Formation in Staphylococcus aureus.

BACKGROUND: Staphylococcus aureus as a causative agent of hospital-acquired infections has been considered as the primary concern in biomaterial-related infections (BAIs). METHODS: Following the purification of polysaccharide intercellular adhesion (PIA) as an efficient macromolecule in biofilm formation in the native condition, recombinant S. epidermidis surface-exposed rSesC protein, with the most homology to clumping factor A (ClfA) in S. aureus was cloned and expressed in a prokaryotic host as well. Fourier transform infrared spectrometry (FTIR) and Western blotting procedure analyzed purified PIA and protein, respectively. Then, the immune response was evaluated by measuring total IgG titers. Moreover, the capacity of Anti-biofilm forming activity of arisen antibodies to a biofilm-forming S. aureus strains was assessed by the semi-quantitative micro-plate procedure. RESULTS: Data showed that the total IgGs were boosted in mice immunized sera. By performing an inhibition assay, the biofilm inhibitory effect of secreted antibodies to test strain was observed. Arisen antibodies against the mixture significantly were more potent than PIA and rSesC, when comparing individual antigens in a biofilm inhibition assay. CONCLUSION: immunization of mice with mentioned antigens especially a mixture of them, could eliminate the biofilm formation process in S. aureus. Hopefully, this study corresponds to the suggestion that the immunization of mice with PIA and rSesC candidate vaccines could protect against S. aureus infection.

Isolation of High Level Macrolide Resistant Bordetella pertussis Without Transition Mutation at Domain V in Iran.

BACKGROUND: Bordetella pertussis, as a causative agent of whooping cough, due to the annual rise y of infection cases, failure of prophylaxis and treatment by macrolides, is considered as the new concern in the health care system. OBJECTIVES: The main objective of this study was the determination of single nucleotide polymorphisms (SNPs) at domain V, as the main binding site for macrolides, following the identification of high level macrolides resistant B. pertussis. MATERIALS AND METHODS: Following the identification of 11 recovered B. pertussis isolates, from a total of 1084 nasopharyngeal swabs, by using the biochemical and molecular methods, the activities of erythromycin, azithromycin and clarithromycin antibiotics against the recovered isolates were examined. Subsequently, A-G transition mutations in domain V were analyzed by molecular techniques, such as Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and sequencing. RESULTS: After susceptibility testing, one strain was detected as a high level macrolide resistant B. pertussis (Erythromycin = 128 µg/mL, Clarithromycin > 256 µg/mL). After sequencing and PCR-RFLP methods, transition mutations in positions 2047 and 2058 of the mentioned domain were not observed. CONCLUSIONS: Although previous studies have shown that A-G transition mutations in 23 SrRNA gene (domain V) are the main reason for the occurrence of high level macrolides resistance in B. pertussis, however, the mentioned single nucleotide polymorphisms (SNPs) have not been detected in our resistant strain. This is the first report of high level macrolide resistant B. pertussis, without SNPs in domain V, in Iran.

Detection of both vanA & vanB genes in vanA phenotypes of Enterococci by Taq Man RT-PCR.

Twenty seven isolates of vancomycin resistant Enterococci based on the disk diffusion and E- test have been screened; being found eight (0.3%) clinical isolates of vanA & vanB through Taq Man Real Time PCR assay. This study shows the presence of both vanA & vanB genotypes in vanA phenotypes clinical isolates in the three hospitals in Iran.

Detection of both vanA & vanB genes in vanA phenotypes of Enterococci by Taq Man RT-PCR

Twenty seven isolates of vancomycin resistant Enterococci based on the disk diffusion and E- test have been screened; being found eight (0.3%) clinical isolates of vanA & vanB through Taq Man Real Time PCR assay. This study shows the presence of both vanA & vanB genotypes in vanA phenotypes clinical isolates in the three hospitals in Iran.