Prevalence and molecular characterization of Listeria spp. and Listeria monocytogenes isolated from fish, shrimp, and cooked ready-to-eat (RTE) aquatic products in Iran

The prevalence of Listeria spp. and Listeria monocytogenes was investigated by biochemical and molecular methods in a total of 201 fish, shrimp, and ready-to-eat seafood samples collected from Iranian supermarkets. Thirty-six samples were also collected from a seafood processing plant. Twenty-one (8.86) of the total retail and processing plant samples (237) were positive for Listeria spp., confirmed by a simplex PCR assay for the prs gene. Seven (2.95) of the total samples were also positive for L. monocytogenes. The presence of four virulence-associated genes in the seafood isolates (inlA, inlC, inlJ, and hlyA) was examined using PCR and the results were compared with seven clinical L. monocytogenes strains. All virulence genes were detected in six fish isolates. One fish isolate did not show amplification of the inlJ and inlC genes. However, all seven clinical strains were positive for internalin genes. Furthermore, a multiplex PCR assay was employed to evaluate the major L. monocytogenes genoserogroups' distribution. The results revealed that the serotypes of lineage II are most frequently present in clinical and food isolates. In summary, PCR screening for both the major L. monocytogenes serovars and virulence genes revealed the potential public health risk posed by L. monocytogenes in aquatic products. © 2016 Elsevier Ltd

Immunization with Bivalent Flagellin Protects Mice against Fatal Pseudomonas aeruginosa Pneumonia

Pseudomonas aeruginosa lung infections present a major challenge to healthcare systems worldwide because they are commonly associated with high morbidity and mortality. Here, we demonstrate the protective efficacy of type a and b flagellins (bivalent flagellin) against acute fatal pneumonia in mice. Mice immunized intranasally with a bivalent flagellin vaccine were challenged by different flagellated strains of P. aeruginosa in an acute pneumonia model. Besides the protective effect of the vaccine, we further measured the host innate and cellular immunity responses. The immunized mice in our study were protected against both strains. Remarkably, active immunization with type a or b flagellin significantly improved survival of mice against heterologous strain compared to flagellin a or b antisera. We also showed that after an intranasal challenge by P. aeruginosa strain, neutrophils are recruited to the airways of vaccinated mice, and that the bivalent flagellin vaccine was proved to be protective by the generated CD4+IL-17+ Th17 cells. In conclusion, bivalent flagellin vaccine can confer protection against different strains of P. aeruginosa in an acute pneumonia mouse model by eliciting effective cellular and humoral immune responses, including increased IL-17 production and improved opsonophagocytic killing

Targeting Listeria monocytogenes consensus sequence of internalin genes using an antisense molecule

As an intracellular pathogen, Listeria monocytogenes can enter host cells where it can replicate and escape detection and eradication by the host immune response making the clearance of infection very challenging. Furthermore, with the advent of antimicrobial resistance, the need for alternative targets is inevitable. Internalin proteins are crucial to this bacterium as they contribute to bacterial entry to the systemic circulation. In this study, we targeted a highly conserved region of these proteins by an antisense sequence that was covalently conjugated to the cell penetrating peptides (CPP) to overcome the challenging delivery barriers. Then, we evaluated the efficiency of this construct in vitro. We also assessed the antigenicity, cytotoxicity, and probability of apoptosis induction by this construct. The studied CPP-PNA inhibited bacterial growth and suppressed the mRNA expression of internalins in a dose-dependent manner. In addition, at all studied concentrations, CPP-PNA significantly reduced the invasion rate of L. monocytogenes in the examined cell lines. Moreover, different concentrations of CPP-PNA did not have a significant antigenic, cytotoxic, and apoptotic properties compared to the control. These results suggest the effectiveness of CPP-antisense in targeting the mRNAs of internalins for various research, therapeutic and preventive purposes. However, additional research is required to evaluate the potency, safety, and pharmacokinetics of this compound for the prevention and treatment of listeriosis

Accuracy of detection of Streptococcus pneumoniae in clinical laboratories by using phenotypic and molecular methods

Introduction: Streptococcus pneumoniae, is one of the most important bacterial pathogens and a member of viridians streptococci group. Accurate identification and differentiation of this form of bacteria from other relative streptococci, is the base of epidemiological study of this type of organism. The aim of this study was to evaluate the accuracy of detection of Streptococcus pneumoniae in clinical laboratories in Tehran, by using phenotypic and genotypic methods. Materials and Methods: A total number of 110 isolates, identified as pneumococci by some clinical laboratories in Tehran, were collected between March 2010 to May 2012.After isolating the colonies, biochemical identification tests by optochin susceptibility (Mast) and bile solubility (direct method) methods were performed. After DNA extraction, PCR was performed to define lytA gene as a molecular identification for Streptococcus pneumonia. Results: After re-identifying the isolates, fifty of them were determined as true pneumococci, and other remaining sixty isolates were identified as: three gram negative coccobacilli, seven non alpha hemolytic streptococci, and fifty Viridans streptococci. Most of misidentifications were related to respiratory and eye infecting streptococci. Unlike non pneumococcal isolates, all 50 pneumococcal isolates were positive for lytA gene. Conclusion: There was 55 error in detection of pneumococci in this study. The use of optochin susceptibility test as the sole detection tool and also lack of supplemental tests and proper quality controlling, are the main causes of failure in diagnosing pneumococci in Iran. Misidentifications may result in incorrect epidemiological data gathering, unnecessary treatment, and false increased antibiotic resistance reports for this organism. Regarding the high incidence of inaccuracies in defining this specific type of microorganism, we suggest the presence of a clinical microbiologist in the hospital laboratories to perform the right diagnostic tests and quality controlling would be essential. © 2015, Semnan University of Medical Sciences. All rights reserved

Epidemiological burden of Listeria monocytogenes in Iran

Objective(s): Listeria monocytogenes is a foodborne pathogenic bacteria causing the infection listeriosis, which possibly affects all people, particularly immunocompromised persons and pregnant women. This microorganism can be found in several processed foods, dairy products, raw milk, meat and fish products, seafoods, eggs, fruits, and vegetables. This review discusses about the epidemiological significance, incidence, contamination routes of L. monocytogenes in different products and current data about listeriosis in the Iran. Materials and Methods: For accessing to relevant articles and studies, a search was done in main databases and also, almost all Iranian published articles were studied in this field. Results: Outbreaks of listeriosis have been reported in many parts of the worldwide, however there is scanty data about the prevalence of listeriosis in Iran. Accordingly, as a result of high incidence of L. monocytogenes in women with bad obstetric history or history of abortions, diagnosis procedures for detection of L. monocytogenes and timely treatment was suggested. Conclusion: In spite of low incidence of infection in the past, increased interest for lightly preserved and/or ready-to-eat (RTE) food products has recently led to increasing of L. monocytogenes prevalence which has become a public health concern. Subsequently, further researches about the prevalence of L. monocytogenes and also antibiotic susceptibility testing is needed to enable the detection of the contaminated foods, as well as ensures the effective treatment. © 2018, Mashhad University of Medical Sciences. All rights reserved

Determination of the frequency of β-lactamase genes (bla SHV, bla TEM, bla CTX-M) and phylogenetic groups among ESBL-producing uropathogenic Escherichia coli isolated from outpatients

Escherichia coli accounts for 70-95 of community-acquired urinary tract infections (UTIs). Recently, there has been an increase in the prevalence of extended-spectrum β-lactamase (ESBL) in the community which required an accurate identification for better management. Therefore, the current study was performed to determine the antimicrobial resistance pattern, investigate ESBL phenotypes and genotypes (blaCTX-M, bla TEM and bla SHV genes) and determine the phylogenetic groups among ESBL-positive isolates from outpatients. One hundred and eighty-three positive urine samples were collected from 4450 outpatient clinic attendees. Antibiotic susceptibility was determined and ESBL phenotype screening was carried out using disk diffusion agar and combination disk techniques, respectively. The assessment of the presence of the blaCTX-M, bla TEM and blaSHV genes and phylogenetic grouping were performed using the polymerase chain reaction (PCR) method. Out of 183 E. coli isolates, 59 (32.2) showed a positive ESBL phenotype. The prevalence of ESBL-producing E. coli was higher in males (57.4). Fifty-seven of the ESBL-producing strains carried at least one of the β-lactamase genes (bla CTX-M, bla TEM, bla SHV). Phylotyping of multi-drug resistant isolates indicated that the isolates belonged to B2, A and D phylogroups. Analysis of resistance patterns among these phylogroups revealed that 74.4, 55.3 and 29.7 of the isolates in the B2 group were resistant to trimethoprim-sulfamethoxazole, ciprofloxacin and gentamicin, respectively. Most of the strains in the phylogroup B2 carried the bla CTX-M gene. All the ESBL-producing isolates were placed in one of the four phylogenetic groups. The presence of CTX-M and resistance to quinolones were more frequent in B2 strains than in non-B2 strains. © 2020 Azam Fattahi et al., published by De Gruyter, Berlin/Boston

Prevalence, and virulence determination of listeria monocytogenes strains isolated from clinical and non-clinical samples by multiplex polymerase chain reaction

Introduction: This study aimed to determine the prevalence, and virulence factors of Listeria monocytogenes isolated from various samples by multiplex polymerase chain reaction (MPCR). Methods: A total of 617 isolates were obtained and MPCR was employed for detection of the inlA, inlC, and inlJ genes. Results: L. monocytogenes was detected in 46 (7.45) of the 617 specimens. inlA, inlC, and inlJ were detected in 100, 76.26, and 71 isolates, respectively. Conclusions: This study validated MPCR in the analysis and rapid detection of L. monocytogenes. The role of the genes in pathogenesis of the strains can also be affirmed. © 2016, Sociedade Brasileira de Medicina Tropical. All rights reserved

Molecular detection of blaVEB-1 beta-lactamase encoding gene among extended spectrum B-Lactamase positive wound isolates of Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa is considered as a leading cause of nosocomial infections. Burn and wound infections are mainly caused by multidrug-resistant P. aeruginosa isolates. Drug resistance frequently occurs among nosocomial isolates and can usually resist a myriad of antibiotics such as novel β-lactam antibiotics. Detection of multidrug-resistant isolates could assist better drug administration. Objectives: The aim of this study was to detect Extended Spectrum Beta-Lactamases (ESBL) positive wound isolates and the genes encoding blaVEB-1 ESBL among wound isolates of P. aeruginosa. Materials and Methods: A total of 89 wound isolates of P. aeruginosa were collected from patients (47 (n = 42) were male and 53 (n = 47) were female) at six Iranian hospitals between years 2009 and 2011. Antibiotic susceptibility and phenotypic ESBL production tests were conducted. The combined disk was used to determine ESBLs production. The blaVEB-1 gene was detected with the polymerase chain reaction (PCR). Results: The majority of the wound isolates were resistant to augmentin (90, n = 80) and cefpodoxime (87.6, n = 78). However, the majority was susceptible to imipenem and meropenem. Fifty-eight (42) wound isolates were ESBL positive. The antibiotic resistance amongst ESBL positive isolates was relatively higher than ESBL negative isolates. Twenty-three (40) ESBL-positive isolates amplified the blaVEB-1 gene. Conclusions: More than behalf of the wound isolates were ESBL positive, and the presence of blaVEB-1 was determined in less than half of these isolates. Fortunately, resistance to imipenem and meropenem was low. © 2015 Pediartric Infections Research Center

Thefromdominancepatients andof healthypilus isletindividuals1 in pneumococcal isolates collected

Background: Pili in Streptococcus pneumoniae have been shown to be one of the adherence factors for epithelial cells in the human upper respiratory tract. Two types of pilus-like structures (pilus islet-1 and pilus islet-2) have been distinguished in S. pneumoniae. Objectives: To investigate the presence of pilus islet-1 (PI-1) in S. pneumoniae and the correlation between our isolates. Materials and Methods: In this study, 162 S. pneumoniae isolates were collected fromclinical specimens, and normal flora were also examined for the distribution of PI-1 using the presence of the rlrA and rrgC genes as markers for this islet and sipA as an indicator of pilus islet-2 (PI-2). BOX-PCR analyses were performed to determine the genetic relationship between isolates. Results: The results confirmed the presence of rlrA and rrgC genes in both clinical (n = 39) and normal flora (n = 26) isolates. Theminimal inhibitory concentration results revealed that the rate of resistance of these isolates to the three antibiotics tested ranged from 26 for penicillin to 46 for erythromycin and tetracycline. Furthermore, 12 of the isolates were resistant to all three antibiotics. Strain typing using repetitive element BOX-PCR analysis among the 65 isolates identified 8 different band patterns. Conclusions: Our results indicated that the dissemination of PI-1 was widespread in S. pneumoniae isolates, although no PI-2 isolates were detected. Furthermore, the frequency of rlrA and rrgC of clinical isolates was significantly more than that of normal flora isolates. © 2016, Ahvaz Jundishapur University of Medical Sciences

A bioassay-guided fractionation scheme for characterization of new antibacterial compounds from Prosopis cineraria aerial parts

Background and Objectives:Due to the importance of finding of new antibacterial agents, the antibacterial properties of Prosopis cinerariaaerial parts were investigated using a bioassay guided fractionation scheme. Materials and Methods:The organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane and ethyl acetate. The MICs of fractions were determined against some human pathogenic bacteria using broth micro-dilution assay. The primary characterization and identification of bioactive substance(s) was based on a bio-autograph- ical method using HPTLC and flash chromatography in parallel with agar overlay assays. Finally the exact mass of effective compound(s) was determined by LC-MS. Results:The best antibacterial activities were related to the ethyl acetate fraction. The effective antibacterial compound of the plant were 2 substances with molecular weight of 348 and 184 Dalton that inhibited the growth of assessed Gram positive bacteria with MIC values lower than 125 to 62.5 µg/ml synergistically. Conclusion: Further analysis using nuclear magnetic resonance could reveal the exact structure of these two antibacterial substances. These 2 effective antibacterial compounds could be applied as lead compound for synthesis of new antibacterial agents. © 2016, Tehran University of Medical Science. All Rights reserved