RESUMEN
Drug resistant strains of M. tuberculosis pose serious public health problem in Egypt. Inadequate treatment regimens and inefficient laboratory diagnosis of drug-resistant strains are likely major contributors to these problems. Mutations of the rpoB gene associated with rifampin resistance were studied in 25 rifampin resistant clinical strains of Mycobacterium tuberculosis isolated in Egypt. Of the 25 resistant isolates, 17 had a mutation in the 81 bp region of the rpoB gene by single strand conformation polymorphism [SSCP] and DNA sequencing. Only two resistance patterns could be detected by SSCP analysis. Sequence analysis revealed that Ser531AELeu arose most frequently missense mutation [76%] followed by Asp516AE Val [24%]. The sensitivity and specificity of the SSCP result were 100% compared with that of the DNA sequencing. These results suggest that SSCP is an efficient method for predicting rifampin resistance which would reduce the time required for susceptibility testing from 4-8 weeks to few days. It is useful for rapid screening of rifampin resistance in isolates of M. tuberculosis
RESUMEN
Escherichia coli, the predominant species among the facultative anaerobic normal flora of the intestine, plays an important role in maintaining intestinal physiology. It is also commonly found in feces from humans and animals that it is considered as an indicator of fecal contamination when found in water, food, or the environment. For many years the principal method of identifying pathogenic strains of Escherichia coli has been O-H serotyping based on the presence of the cell surface lipopolysaccharide O antigen and the flagellar H antigen. The H antigen of E. coli is specified by a single structural subunit [flagellin] encoded by the fliC gene. For the species as a whole, there are 56 recognized antigenic types [H types], which, in combination with the O antigen, are often associated with bacterial clones that cause specific kinds of disease. In this study, we characterized the E. coli flagellar genes by restriction of their amplified sequence using the RsaI enzyme. A total of 101 strains of Escherichia coli [48 reference strains, and 53 clinical strains] were characterized by RsaI restriction of the amplified flagellin gene [fliC]. The amplified fliC product was a single band between 1.3 and 2.6 kbp. A total of 44 different patterns were observed after RsaI restriction. The proposed determination of fliC restriction patterns should be helpful for epidemiological studies
RESUMEN
Enterococci which are part of the normal intestinal flora are opportunistic human pathogens. The two most important species, E.faecalis and E.faecium are among the leading causes of nosocomial infections that may cause severe infections including endocarditis, urinary tract infection, septicemia and wound infections which are often difficult to treat. The aim of the present study was Isolation and characterization of enterococci from patients with nosocomial infections were performed to determine the most common species responsible for nosocomial infections and to study the patterns of resistance of the isolated strains
Methods: This study is a twelve-month prospective study in which different clinical samples including urine, pus, blood and ascetic fluids were collected from patients with evidence of nosocomial infection at the period from December 2005 to December 2006. These specimens were subjected to a culture on blood and Mac Conkey agar, gram staining, catalase test, bile aesculin hydrolysis and salt tolerance test for isolation of enterococci. Enterococcal strains were further identified to the species level by using biochemical tests which are based on sugar fermentation, pyruvate utilization and arginine decarboxylation. Antimicrobial susceptibility was done for the isolates by disc diffusion method and agar dilution for vancomycin MIC determination
Results: The enterococci infection rate in our hospital was 3.3% isolated from urine [65%], pus [30%] and from ascetic fluid [5%] [p>0.005]. The majority of the isolates were E.faecalis [55%] followed by E. faecium [30%], E. durans [10%] and E. avium [5%]. The most common source of isolation was the internal medicine departments and ICUs [p>0.05]. By disc diffusion method, E.faecalis was more resistant than E.faecium to tertracyclines [P<0.05] and aminoglycosides [P<0.01]. Otherwise, E.faecium was more resistant than E.faecalis to penicillins [P<0.01] and quinolones [P<0.001]. All the strains were sensitive to vancomycin by disc diffusion method. The 20 isolates were further tested by agar dilution method to determine their vancomycin MICs. All the strains were vancomycin susceptible with MICs ranged from 1 micro g/ml to 4 micro g/ml
RESUMEN
Enterococci which are part of the normal intestinal flora are opportunistic human pathogens. The two most important species, E.faecalis and E.faecium are among the leading causes of nosocomial infections that may cause severe infections including endocarditis, urinary tract infection, septicemia and wound infections which are often difficult to treat. The aim of the present study was Isolation and characterization of enterococci from patients with nosocomial infections were performed to determine the most common species responsible for nosocomial infections and to study the patterns of resistance of the isolated strains
Methods: this study is a twelve-month prospective study in which different clinical samples including urine, pus, blood and ascetic fluids were collected from patients with evidence of nosocomial infection at the period from December 2005 to December 2006. These specimens were subjected to a culture on blood and Mac Conkey agar, gram staining, catalase test, bile aesculin hydrolysis and salt tolerance test for isolation of enterococci. Enterococcal strains were further identified to the species level by using biochemical tests which are based on sugar fermentation, pyruvate utilization and arginine decarboxylation. Antimicrobial susceptibility was done for the isolates by disc diffusion method and agar dilution for vancomycin MIC determination
Results: The enterococci infection rate in our hospital was 3.3% isolated from urine [65%], pus [30%] and from ascetic fluid [5%] [p>0.005]. The majority of the isolates were E.faecalis [55%] followed by E. faecium [30%], E. durans [10%] and E. avium [5%]. The most common source of isolation was the internal medicine departments and ICUs [p>0.05]. By disc diffusion method, E.faecalis was more resistant than E.faecium to tertracyclines [P<0.05] and aminoglycosides [P<0.01]. Otherwise, E.faecium was more resistant than E.faecalis to penicillins [P<0.01] and quinolones [P<0.001]. All the strains were sensitive to vancomycin by disc diffusion method. The 20 isolates were further tested by agar dilution method to determine their vancomycin MICs. All the strains were vancomycin susceptible with MICs ranged from 1 micro g/ml to 4 micro g/ml
RESUMEN
Drug resistant strains of M. tuberculosis pose serious public health problem in Egypt. Inadequate treatment regimens and inefficient laboratory diagnosis of drug-resistant strains are likely major contributors to these problems. Mutations of the rpoB associated with rifampin resistance were studied in 25 rifampin resistant clinical strains of Mycobacterium tuberculosis isolated in Egypt. Of the 25 resistant isolates, 17 had a mutation in the 81 bp region of the rpoB gene by single strand conformation polymorphism [SSCP] and DNA sequencing. Only two resistance patterns could be detected by SSCP analysis. Sequence analysis revealed that Ser[531] - Leu arose most frequently missense mutation [76%] followed by Asp[516] - Val [24%]. The sensitivity and specificity of the SSCP result were 100% compared with that of the DNA sequencing. These results suggest that SSCP is an efficacious method for predicting rifampin resistance and would reduce the time required for susceptibility testing from 4-8 weeks to few days and it is useful for rapid screening of rifampin resistance in susceptible and fully resistant isolates of M. tuberculosis
RESUMEN
Mycobacterium tuberculosis strains resistant to streptomycin (SM), isoniazid (INH), and/or rifampin (RIF) as determined by the conventional Lõwenstein-Jensen proportion method (LJPM) were compared with the E test, a minimum inhibitory concentration susceptibility method. Discrepant isolates were further evaluated by BACTEC and by DNA sequence analyses for mutations in genes most often associated with resistance to these drugs (rpsL, katG, inhA, and rpoB). Preliminary discordant E test results were seen in 75 percent of isolates resistant to SM and in 11 percent to INH. Discordance improved for these two drugs (63 percent) for SM and none for INH when isolates were re-tested but worsened for RIF (30 percent). Despite good agreement between phenotypic results and sequencing analyses, wild type profiles were detected on resistant strains mainly for SM and INH. It should be aware that susceptible isolates according to molecular methods might contain other mechanisms of resistance. Although reproducibility of the LJPM susceptibility method has been established, variable E test results for some M. tuberculosis isolates poses questions regarding its reproducibility particularly the impact of E test performance which may vary among laboratories despite adherence to recommended protocols. Further studies must be done to enlarge the evaluated samples and looked possible mutations outside of the hot spot sequenced gene among discrepant strains.