Vancomycin-resistant enterococci in King Chulalongkorn Memorial Hospital: a 5-year study.

The emergence of hospital acquired infections with bacteria resistant to antimicrobials such as vancomycin resistant enterococci (VRE) has become a worldwide concern. The authors studied the prevalence and surveillance of 5 years study of VRE in King Chulalongkon Memorial Hospital and phenotype of these resistance strains. A total of enterococci 1854 isolates were collected from clinical specimens from 1995 to 1999. Screening vancomycin resistance was identified by the agar plated method and minimal inhibitory concentration (MIC) of vancomycin was determined for vancomycin-resistance strains by E-test. The results demonstated that 15 (0.81%) VRE were isolated from 1,854 specimens. Fourteen VRE were identified as Enterococcus faecium and one strain was Enterococcus faecalis. All of these strains, carrying the VanB phenotype, were susceptible to teicoplanin. Similar to other studies, most VRE strains are E. faecium. To the authors' knowledge, this is the first VRE study carried out in King Chulalongkorn Memorial Hospital. The results showed a low prevalence of VRE and surveillance of 5 years study demonstated a gradual increase of VRE. Therefore, it is important to continue periodic surveys of VRE to prevent the spread of VRE in hospitals.

Amplification of P1 gene by polymerase chain reaction for detection of Mycoplasma pneumoniae.

Mycoplasma pneumoniae is a causative agent of human respiratory tract infection of which the clinical features are not significantly different from those of infections caused by other respiratory pathogens. The diagnosis is based principally on laboratory tests. Since conventional methods such as culture and serological tests are time-consuming, insensitive, and non-specific, polymerase chain reaction (PCR) was employed for laboratory diagnostics. This study was aimed to develop PCR method to detect M. pneumoniae by designing primers to amplify fragment of the P1 adhesin gene. Two protocols, PCR-probe hybridization and nested PCR, were carried out. False-positive result due to amplicon carry over was prevented by using dUTP instead of dTTP and the addition of enzyme uracil DNA glycosylase (UDG). For nested PCR, UDG was added only in the first round reaction mixture. The sensitivity of PCR was 10 fg of M, pneumoniae DNA as detected by agarose gel electrophoresis and increased to be 1 fg as detected by either probe hybridization or nested PCR. The specificity of PCR was tested with DNAs from Mycoplasma spp, a variety of different bacterial genera and human leukocyte. All gave negative results. Considering of the speed, sensitivity, specificity and the prevention of amplicon carryover, the developed PCR-based protocols were suitable and reliable for the detection of M. pneumoniae in routine laboratory.