Open Microbiology Journal最新文献

Mucopolysaccharidosis type II is a human recessive disease linked to the X chromosome caused by deficiency of lysosomal enzyme Iduronate 2-Sulfate Sulfatase (IDS), which leads to accumulation of glycosaminoglycans in tissues and organs. The human enzyme has been expressed in Escherichia coli and Pichia pastoris in attempt to develop more successful expression systems that allow the production of recombinant IDS for Enzyme Replacement Therapy (ERT). However, the preservation of native signal peptide in the sequence has caused conflicts in processing and recognition in the past, which led to problems in expression and enzyme activity. With the main object being the improvement of the expression system, we eliminate the native signal peptide of human recombinant IDS. The resulting sequence showed two modified codons, thus, our study aimed to analyze computationally the nucleotide sequence of the IDSnh without signal peptide in order to determine the 3D structure and other biochemical properties to compare them with the native human IDS (IDSnh). Results showed that there are no significant differences between both molecules in spite of the two-codon modifications detected in the recombinant DNA sequence.

Background: Several nontuberculous mycobacteria (NTM) were previously isolated from diverse environments such as water, soil, sewage, food and animals. Some of these NTM are now known to be opportunistic pathogens of humans.

Objective: The main purpose of the study was to identify NTM isolates stored at the National Microbiology Reference Laboratory (NMRL) and were previously isolated from humans during a national tuberculosis (TB) survey.

Methods: Pure NTM cultures already isolated from human sputum samples during the national TB survey were retrieved from the NMRL and used for this study. DNA was extracted from the samples and 16S ribosomal RNA gene amplified by polymerase chain reaction. The amplicons were sequenced and bioinformatics tools were used to identify the NTM species.

Results: Out of total of 963 NTM isolates stored at the NMRL, 81 were retrieved for speciation. Forty isolates (49.4%) were found to belong to Mycobacterium avium-intracellulare complex (MAC) species. The other 41 isolates (50.6%) were identified as M. lentiflavum (6.2%), M. terrae complex (4.9%), M. paraense (4.9%), M. kansasii (3.7%), M. moriokaense (3.7%), M. asiaticum (2.5%), M. novocastrense (2.5%), M. brasiliensis (2.5%), M. elephantis (2.5%), M. paraffinicum (1.2%), M. bohemicum (1.2%), M. manitobense (1.2%), M. intermedium (1.2%), M. tuberculosis complex (1.2%), M. parakoreense (1.2%), M. florentinum (1.2%), M. litorale (1.2%), M. fluoranthenivorans (1.2%), M. sherrisii (1.2%), M. fortuitum (1.2%) and M septicum (1.2%). Two isolates (2.5%) could not be identified, but were closely related to M. montefiorense and M. phlei respectively. Interestingly, the MAC species were the commonest NTM during the survey.

Conclusion: The study emphasizes the importance of identifying species of NTM in Zimbabwe. Future studies need to ascertain their true diversity and clinical relevance.

Helicobacter pylori is a global health problem which has encouraged scientists to find new ways to diagnose, immunize and eradicate the H. pylori infection. In silico studies are a promising approach to design new chimeric antigen having the immunogenic potential of several antigens. In order to obtain such benefit in H. pylori vaccine study, a chimeric gene containing four fragments of FliD sequence (1-600 bp), UreB (327-334 bp),VacA (744-805 bp) and CagL(51-100 bp) which have a high density of B- and T-cell epitopes was designed. The secondary and tertiary structures of the chimeric protein and other properties such as stability, solubility and antigenicity were analyzed. The in silico results showed that after optimizing for the purpose of expression in Escherichia coli BL21, the solubility and antigenicity of the construct fragments were highly retained. Most regions of the chimeric protein were found to have a high antigenic propensity and surface accessibility. These results would be useful in animal model application and accounted for the development of an epitope-based vaccine against the H. pylori.

Commensals of the human body can shift to a pathogenic phase when the host immune system is impaired. This study aims to investigate the effect of seven yeast and two bacterial commensals and opportunistic pathogens isolated from blood and the female genital tract on the transepithelial electrical resistance (TER) of human cervical epithelial cell cultures (HeLa). The pathogens Candida tropicalis, C. parapsilosis, C. glabrata, C. krusei, C. albicans and Saccharomyces cerevisiae, caused a significant decrease in TER as compared to the controls; Lactobacillus spp caused a significant increase in TER versus the controls and Escherichia coli had no effect on the TER of the cell monolayers. The above data show that Candida spp., S. cerevisiae and Lactobacillus spp. have a non-selective effect on the TER of HeLa cell monolayers. These results are consistent with the in vivo non-selective action of these microorganisms on the various human mucosal epithelia.

Bacteroides fragilis is an extensively studied anaerobic bacterium comprising the normal flora of the human gut. B. fragilis is known to be one of the most commonly isolated species from clinical samples and has been shown to cause a wide range of pathologies in humans [1, 2]. As an opportunistic pathogen B. fragilis can cause abscess formation and bacteremia [2]. Additionally in its enterotoxigenic form, B. fragilis is a known cause of diarrheal illness, is associated with inflammatory bowel disease, and has been recently characterized in patients with colon cancer [3 - 5]. As research in the field of the gut microbiome continues to expand at an ever increasing rate due to advances in the availability of next generation sequencing and analysis tools it is important to outline various molecular methods that can be employed in quickly detecting and isolating relevant strains of B. fragilis. This review outlines methods that are routinely employed in the isolation and detection of B. fragilis, with an emphasis on characterizing enterotoxigenic B. fragilis (ETBF) strains.

Human noroviruses are a group of viral agents that afflict people of all age groups. The viruses are now recognized as the most common causative agent of nonbacterial acute gastroenteritis and foodborne viral illness worldwide. However, they have been considered to play insignificant roles in the disease burden of acute gastroenteritis for the past decades until the recent advent of new and more sensitive molecular diagnostic methods. The availability and application of the molecular diagnostic methods have led to enhanced detection of noroviruses in clinical, food and environmental samples, significantly increasing the recognition of noroviruses as an etiologic agent of epidemic and sporadic acute gastroenteritis. This article aims to summarize recent efforts made for the development of molecular methods for the detection and characterization of human noroviruses.

Staphylococcus aureus is an important pathogen that can cause a variety of infections, including superficial and systematic infections, in humans and animals. The persistent emergence of multidrug resistant S. aureus, particularly methicillin-resistant S. aureus, has caused dramatically economic burden and concerns in the public health due to limited options of treatment of MRSA infections. In order to make a correct choice of treatment for physicians and understand the prevalence of MRSA, it is extremely critical to precisely and timely diagnose the pathogen that induces a specific infection of patients and to reveal the antibiotic resistant profile of the pathogen. In this review, we outlined different PCR-based approaches that have been successfully utilized for the rapid detection of S. aureus, including MRSA and MSSA, directly from various clinical specimens. The sensitivity and specificity of detections were pointed out. Both advantages and disadvantages of listed approaches were discussed. Importantly, an alternative approach is necessary to further confirm the detection results from the molecular diagnostic assays.

Francisella tularensis is the causative pathogen of tularemia and a Tier 1 bioterror agent on the CDC list. Considering the fact that some subpopulation of the F. tularensis strains is more virulent, more significantly associated with mortality, and therefore poses more threat to humans, rapid identification and characterization of this subpopulation strains is of invaluable importance. This review summarizes the up-to-date developments of assays for mainly detecting and characterizing F. tularensis and a touch of caveats of some of the assays.

Imipenem-resistant multi-drug resistant (IR-MDR) Acinetobacter baumannii has been emerged as a morbidity successful nosocomial pathogen throughout the world.To address imipenem being yet the most effective antimicrobial agent against A. baumannii to control outbreaks and treat patients, a systematic review and meta-analysis was performed to evaluate the prevalence of IR-MDR A. baumannii. We systematically searched Web of Science, PubMed, MEDLINE, Science Direct, EMBASE, Scopus, Cochrane Library, Google Scholar, and Iranian databases to identify studies addressing the antibiotic resistance of A. baumannii to imipenem and the frequency of MDR strains in Iran. Out of 58 articles and after a secondary screening using inclusion and exclusion criteria and on the basis of title and abstract evaluation, 51 studies were selected for analysis. The meta-analysis revealed that 55% [95% confidence interval (CI), 53.0-56.5] of A. baumannii were resistant to imipenem and 74% (95% CI, 61.3-83.9) were MDR. The MDR A. baumannii population in Iran is rapidly changing toward a growing resistance to imipenem. Our findings highlight the critical need for a comprehensive monitoring and infection control policy as well as a national susceptibility review program that evaluates IR-MDR A. baumannii isolates from various parts of Iran.