Antibiotic resistance of Salmonella enterica producing Extended-spectrum B-lactamases [ESBLs] type CMY-2, in poultry

Background and Objective: Salmonella is one of the most important zoonotic pathogens responsible for food-borne infections all over the world. Poultry products are widely acknowledged to be a significant reservoir for Salmonella. This study was done to evaluate the antibiotic resistant of Salmonella enterica producer of beta lactamase spectrum in poultry

Methods: In this descriptive - laboratort study 70 Salmonella enterica serotypes were collected from poultry. All Salmonella isolates were tested to antimicrobial susceptibility testing by the Kirby-Bauer disk diffusion according to Clinical Laboratory Standards Institute [CLSI]. Twenty-nine antibiotics were used in this study. Klebsiella pneumoniae; ATCC 700603 was used as quality control strains. The isolates were determined to be ESBL-producing Salmonella by the conventional double-disk synergy and genotypic method

Results: Among 70 salmonella isolates, the most prevalent serotypes were S.typhimurium and S.enteritidis. All serotypes were susceptible to gentamicin, ciprofloxacin, oflaxacin, imipenem, enrofloxacin. The common resistance was observed to cephalexin [96%], cefazolin [96%] and cephalotin [65%]. Among the 70 Salmonella isolates studied, multi-drug resistance was observed in 59 [84%] isolates. Forty-seven [67%] isolates were found to be ESBL-producing isolates. PCR assay of all isolates showed that 17 isolates [33.3%] carried bala CMY2 gene

Conclusion: This study showed that antibiotic resistance to Salmonella enterica serotypes is due to beta lactamase enzyme in this strain is considerably increased in poultry

[Studying the prevalence of TetA and TetB in kelebsiella, proteus and Enterobacter isolated from urinary tract infection]

Background: Nowadays, the resistance to antibiotics in bacteria encountered many physicians around the world; it is an issue that has created numerous problems in the treatment, like urinary tract infection, as a common infection. The aim of this study was to evaluate prevalence of tetracycline resistant genes in Enterobacteriaceae family [Proteus, Enterobacter and Klebsiella] isolated from urine samples

Materials and methods: In this descriptive study, 230 samples of urinary infection were collected from patients. They were identified by using diagnostic biochemical tests and then antibiotic susceptibility tests were used by ticarcillin, ceftriaxone, cefoxitin, streptomycin, erythromycin and tetracycline antibiotics. Afterwards, DNA plasmids were extracted and PCR was performed by coding proprietary primers resistant to tetracycline [TetA, TetB]

Results: Of 230 suspicious samples, 120 were confirmed after biochemical tests, including 88 Kebsiella, 20 Proteus and 12 Enterobacter. The antibiotic susceptibility test of tetracycline showed 38.33% sensitivity and 34.99% resistance for Klebsiella, 6.66% sensitivity and 3.33% resistance for Enterobacter, and 2.5% sensitivity and 14.16% resistance for Proteus. Out of the 120 samples, 25 Tet[A] gene and 36 Tet[B] were detected

Conclusion: The comparison between the results of cultures and PCR method for the genes Tet[A] and Tet[B] showed that PCR method confirmed antibiogram tests, but for improving sensitivity, accuracy and specificity, other coding tetracycline resistance genes should be studied to reach more conclusive results

Regulation of ERG3, ERG6, and ERG11 genes in antifungal-resistant isolates of candida parapsilosis

Background: Candida parapsilosis is one of the five common strains of yeasts involved in invasive candidiasis. The expression analysis of sterol biosynthesis pathway genes, which are associated with resistance, can assist the better understanding of antifungal resistance mechanisms

Methods: The antifungal susceptibility of 120 clinical C. parapsilosis isolates was examined. The changes in the gene expression related to resistance were analyzed

Results: Eight strains were resistant to fluconazole [FLC], itraconazole [ITC], and amphotericin B [AMB]. The regulation variations included increased mRNA levels of ERG3, ERG6, and ERG11 and decreased mRNA levels of ERG3 and ERG6 in response to FLC. ERG11 mRNA level increases in response to ITC and AMB

Conclusion: The mechanism of resistance to azoles in C. parapsilosis is very similar to C. Albicans. This feature may help to design new treatment strategy for candidiasis

[Alterations of gyrA in Enterobacteriaceae isolated of urinary tract infection resistance to quinolones antibiotics]

Background: Urinary tract infection is one of the most common infections, which if not treated, it can cause serious problems in patients. One of the ways to treat of this infection is antibiotic therapy. Nowaday, antibiotic resistance in microorganisms is a main problem for physicians and patients in the world. The aim of this study was to evaluate the genetic resistance to quinolones antibiotics in Enterobacteriaceae isolated in urine samples

Materials and methods: 100 bacteria of Enterobacteriaceae family were isolated from suspected samples of urinary infection. Antibiotic susceptibility of isolated bacteria to quinolone antibiotics, including ciprofloxacin, nalidixic acid, norfloxacin, ofloxacin, levofloxacin and enrofloaxin, was performed by disc diffusion method according to standard guidelines [CLSI 2014]. PCR was performed by specific primers of gyrA gene

Results: Hundred bacteria were isolated of clinical urine sample including 60 E.coli, 32 Klebsiella, 3 Enterobacter, and 5 Proteus. Antibiotic resistance to ciprofloxacin were 36%, nalidixic acid 45%, norfloxacin 38%, ofloxacin 38%, levofloxacin 35% and enrofloaxin 39%. Totally, 36 bacteria were resist to all antibiotics, which 29 bacteria [80.55%] revealed mutation in gyrA gene. Conclusion: This study revealed that Ecoli isolates carry a mutation in gyrA genes. This mutation has an important role in antibiotic resistance to quinolons

effect of EFG1 gene silencing on down-regulation of SAP5 gene, by use of RNAi technology

Efg1 transcription factor is believed to be the main regulator of hyphal formation under many different conditions. In addition, it is responsible for positive regulation of the expression of several hyphalspecific genes. SAP5, which encodes secreted aspartic proteinase, is one of the mentioned genes and is crucial for pathogenicity properties. In the present work we have established the experimental conditions for the use of siRNA in the diploid yeast Candida albicans in order to knock-down the EFG1 gene expression as well as the Efg1-dependent gene, SAP5. The 19-nucleotide siRNA was designed according to cDNA sequence of EFG1 gene in C. albicans and modified-PEG/LiAc method was applied for yeast transfection. To quantify the level of both EFG1 and SAP5 gene expression, the cognate mRNAs were measured in C. albicans by quantitative real-time RT-PCR and data was consequently analyzed by use of REST[registered mark] software. Images taken by fluorescent microscopy method indicated the effectiveness of transfection. According to REST[registered mark] software data analysis, expression of EFG1 gene decreased about 2.5-fold using 500 nM of siRNA. A 7-fold decrease in EFG1 gene expression was observed when applying 1 micro M of siRNA [P<0.05]. Consequently, the expression of SAP5 was significantly down-regulated both in yeast treated with 500 and 1000 nM of siRNA [P<0.05]. In conclusion, post-transcriptional gene silencing [PTGS] is likely to be considered as a promising approach to discover new gene targets so as to design fungal-specific antifungal agents, and it is strongly possible that we are taking the right way to battle with C. albicans-associated infections

Green synthesis of silver nanoparticles: the reasons for and against Aspergillus parasiticus

The enzymatic activity of fungi has recently inspired the scientists with re-explore the fungi as potential biofactories rather than the causing agents of humans and plants infections. In very recent years, fungi are considered as worthy, applicable and available candidates for synthesis of smaller gold, silver and other nano-sized particles. A standard strain of Aspergillus parasiticus was grown on a liquid medium containing mineral salt. The cell-free filtrate of the culture was then obtained and subjected to synthesize SNPs while expose with 1mM of AgNO[3]. Further characterization of synthesized SNPs was performed afterward. In addition, antifungal activity of synthesized SNPs was evaluated against a standard strain of Candida albicans. The reduction of Ag+ ions to metal nanoparticles was investigated virtually by tracing the color of the solution which turned into reddish-brown after 72 h. The UV-vis spectra demonstrated a broad peak centering at 400 nm which corresponds to the particle size much less than 70 nm. The results of TEM demonstrated that the particles were formed fairly uniform, spherical, and small in size with almost 90% in 5-30 nm range. The zeta potential of silver nanoparticles was negative and equal to 15.0 which meets the quality and suggested that there was not much aggression. Silver nanoparticles synthesized by A. parasiticus showed antifungal activity against yeast strain tested and exhibited MIC value of 4 microg/mL. The filamentous fungus, A. parasiticus has successfully demonstrated potential for extra cellular synthesis of fairly monodispersed, tiny silver nanoparticles

Down-regulation of the ALS3 gene as a consequent effect of RNA-mediated silencing of the EFG1gene in candida albicans

The most important virulence factor which plays a central role in Candida albicans pathogenesis is the ability of this yeast to alternate between unicellular yeast and filamentous hyphal forms. Efg1 protein is thought to be the main positive regulating transcription factor, which is responsible for regulating hyphal-specific gene expression under most conditions. ALS3 is one of the Efg1-associated genes encoding a multi-functional adhesive polypeptide, which mediates adherence to diverse host substrates. In this study, the EFG1 gene was knocked down by using synthetic siRNA in C. albicans and the regulation in ALS3 as one of the Efg1-dependent genes was investigated. The 19-nucleotide siRNA was designed based on cDNA sequence of EFG1 gene in C. albicans. Transfection was performed using modified- plyethylen glycol/LiAc method. To quantify the level of EFG1 and the hyphal-specific ALS3 gene expression, the cognate EFG1 and ALS3 mRNA were measured in C. albicans by quantitative real-time RT-PCR. Fluorescent microscopy pictures indicated that transfection was performed successfully. Also, according to relative expression software tool, expression of EFG1 gene was decreased significantly with 500 nM siRNA as well as 1 micro M siRNA [P<0.05]. However, more significant downregulations were observed in the expression of ALS3 in both concentrations of 500 nM and 1 micro M siRNA [P<0.05]. In conclusion, we demonstrated the down-regulation of ALS3 gene as a consequent of applying EFG1-specific siRNA in C. albicans. This may lead us to design anti-fungal-specific agents in order to face with C. albicans-associated infections

Extracellular production of silver nanoparticles by using three common species of dermatophytes: trichophyton rubrum, trichophyton mentagrophytes and microsporum canis

To develop a new green approach for biosynthesis of silver nanoparticles, myconanotechnology has been represented as a novel field of study in nanotechnology. In this study, we have reported the extracellular synthesis of highly stable silver nanoparticles using three species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. Clinical strains of these species were grown in a liquid medium containing mineral salt and incubated at 25[degree sign]C for 5-7 days. The cell-free filtrate of each culture was obtained and subjected to synthesize silver nanoparticles in the presence of 1 mM AgNO[3]. The reduction of Ag+ ions in metal nanoparticles was investigated virtually by tracing the solution color which was switched into reddish-light brown after 72 h. For T. mentagrophytes, a UV-visible spectra demonstrating a strong, quite narrow peak located between 422 and 425 nm was obtained. For M. canis, a fairly wide peak centering at 441 nm and for T. rubrum, a weak spectrum to decipher were observed. According to transmission electron microscopy [TEM] results, fairly uniform, spherical, and small in size with almost less than 50 nm particles were forms in case of T. mentagrophytes. For the other two species, TEM images showed existence of small spherical nanosilvers but not as small as nanoparticles synthesized by T. mentagrophytes. We observed that species belong to a single genus of the fungi have variable ability to synthesize silver nanoparticles extracellulary with different efficiency. Furthermore, the extracellular synthesis may make the process simpler and easier for following processes

[Application of polymerase chain reaction [PCR] in the diagnosis of neurocryptoccosis]

In the last two decades, cryptococcosis has been gaining a distinct public health importance due to the growing number of AIDS cases. Considering the low sensitivity of direct examination with India ink and culture, use of sensitive techniques is crucial in the diagnosis of cryptococcal meningitis. Polymerase Chain Reaction [PCR] can be used to directly detect Cryptococcus neoformans in CSF samples to increase the diagnostic power in cases where conventional methods are unable to detect the organism. In this cross-sectional study, CSF samples were obtained from 25 patients suspected of having neurocryptococcosis. The patients were referred to the Medical Mycology Laboratory of the School of Public Health affiliated to Tehran University of Medical Sciences from March 2009 to February 2010. Three different methods, direct India ink examination, culture and PCR were used to evaluate the CSF samples. Two 102 and 106 of Cryptococcus neoformans dilutions in 1ml of CSF were prepared and examined by the three methods. In PCR method, two primer pairs were selected to amplify the Cryptococcus neoformans URA5 gene. The sequences of primers were for A, B, C and D serotypes. Only in one case PCR, as well as direct examination and culture were positive. All the other samples were negative in PCR, direct examination or culture. Both CSF dilutions were positive in the three tests in the mentioned patient and the positive control. PCR method can efficiently identify both control and positive samples of Cryptococcus neoformans