Isolation and identification of nontuberculous mycobacteria from specimens of lower respiratory tract of transplanted patients based on the evaluation of 16SrRNA gene.

BACKGROUND: Nontuberculous mycobacteria are pervasive microorganisms and are often present as saprophytes in humans, animals, and the environment. Today, these bacteria are known as the most important environmental opportunists and, in the last decades, infections by nontuberculous mycobacteria have multiplied, due to increased immunodeficiency (cancer, transplant recipients, HIV). STUDY DESIGN: This study aimed to investigate the infections by nontuberculous mycobacteria in transplanted patients. METHODS: The study was performed on 57 samples from respiratory secretions of transplant recipients taken by standard methods. Nontuberculous mycobacteria were identified by culture method and molecular identities of clinical isolates were investigated by PCR amplification using 16SrRNA gene and sequence analysis and Blast of the sequences. Demographic data were evaluated by Spss software. RESULTS: The prevalence of nontuberculous mycobacteria in transplant patients was 22.8%, the age of patients was between 23 and 52 years. The most common involvement of nontuberculous mycobacteria in our transplanted individuals were 6 strains of M avium-intracellulare Complex (42.87%), followed by 2 strains of M marinum (14.29%) and 1 strain each (7.14%) of M xenopi, M chelonae, M intracellulare, M kansasii, M simiae. At the conclusion of the tests, one final strain was identified as M tuberculosis (7.14%). CONCLUSION: The prevalence of nontuberculous mycobacteria indicates their importance in the fate of these patients. The identification of nontuberculous mycobacteria is a neglected part of microbiology laboratories, due to the lack of sufficient facilities and the risk associated with their culture. Therefore developing routine methods for the identification of these infections appears to be critical, especially in hospitals with the transplantation ward.

Clinical characteristics and molecular epidemiology of children with meningitis in Tehran, Iran: a prospective study.

The molecular epidemiology of meningitis in children is unclear in Iran, and data are scarce. We aimed to characterize its clinical and paraclinical features as well as to determine the distribution of genotype/capsular types of common bacterial meningitis agents in children in Iran. All children suspected to have meningitis aged 4 days to 15 years were enrolled onto a prospective cross-sectional study from January 2015 to September 2017. Diagnostic values of clinical features, cerebrospinal fluid and serum parameters were evaluated independently and in combination with each other by multivariate logistic regression to develop a diagnostic rule. Genotype/capsular types of all the isolates were determined by targeting serotype-specific genes with uniplex or multiplex PCR. Among 119 patients suspected of having meningitis, 43 had bacterial meningitis, 19 aseptic and one tuberculous; and there were 56 nonmeningitis cases (NMC). Presentation of four features at the same time-cerebrospinal fluid white blood cell count, protein, polymorphonuclear leukocytes and serum C-reactive protein-revealed 100% sensitivity and 86.4% specificity for diagnosis of bacterial meningitis. Haemophilus influenzae type b (60%), Streptococcus pneumoniae serotype 3 (28.5%) and Neisseria meningitidis B (63.5%) were the most prevalent serotypes. This study demonstrated that a well-designed combination of clinical and paraclinical features is useful, but these combinations are not good enough to be relied on as stand-alone exclusionary tests for the diagnosis of bacterial meningitis. In addition, public immunization of infants with the most prevalent bacterial meningitis serotypes is recommended.

Suppressing the CRISPR/Cas adaptive immune system in bacterial infections.

Clustered regularly interspaced short palindromic repeats (CRISPR) coupled with CRISPR-associated (Cas) proteins (CRISPR/Cas) are the adaptive immune system of eubacteria and archaebacteria. This system provides protection of bacteria against invading foreign DNA, such as transposons, bacteriophages and plasmids. Three-stage processes in this system for immunity against foreign DNAs are defined as adaptation, expression and interference. Recent studies suggested a correlation between the interfering of the CRISPR/Cas locus, acquisition of antibiotic resistance and pathogenicity island. In this review article, we demonstrate and discuss the CRISPR/Cas system's roles in interference with acquisition of antibiotic resistance and pathogenicity island in some eubacteria. Totally, these systems function as the adaptive immune system of bacteria against invading foreign DNA, blocking the acquisition of antibiotic resistance and virulence factor, detecting serotypes, indirect effects of CRISPR self-targeting, associating with physiological functions, associating with infections in humans at the transmission stage, interfering with natural transformation, a tool for genome editing in genome engineering, monitoring foodborne pathogens etc. These results showed that the CRISPR/Cas system might prevent the emergence of virulence both in vitro and in vivo. Moreover, this system was shown to be a strong selective pressure for the acquisition of antibiotic resistance and virulence factor in bacterial pathogens.