ABSTRACT
Introduction: Acute respiratory tract infections (ARTIs) are a major cause of morbidity and mortality in paediatric patients. Therefore, early detection of the viral aetiologies of ARTIs is essential for patient management and infection control. In this study, we evaluated the performance of a new multiplex polymerase chain reaction (PCR) assay (xTAG Respiratory Viral Panel [RVP] Fast v2) in the detection of respiratory viruses by comparing it with that of viral culture and direct immunofluorescence (IF) staining. Methods: Nasopharyngeal swab and aspirate samples were collected prospectively from 199 patients who presented with ARTIs at the University Malaya Medical Centre (UMMC) in Kuala Lumpur, Malaysia during a 10-month period. The PCR assay was conducted in parallel with conventional culture and direct IF staining methods. Results: The positive rate of the xTAG RVP Fast v2 assay (78.4%) in detecting respiratory viruses was higher than that of the viral isolation (7.5%) and direct IF (23.1%) methods. Using the xTAG RVP Fast v2 assay, human enterovirus/human rhinovirus (HEV/HRV) was the most frequently detected (46.2%). The xTAG RVP Fast v2 assay revealed mixed infection caused by two or three respiratory viruses in 40 specimens, and these were undetected by the viral isolation and direct IF methods. Conclusion: The xTAG RVP Fast v2 assay was superior to conventional methods in the identification of common respiratory viruses, with higher sensitivity and shorter turnaround times for laboratory results.
ABSTRACT
Aims: The aim of this study was to investigate the genetic relatedness of the most prevalent Candida bloodstream infection (BSI) species in in a Malaysian population via Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) fingerprinting. Methodology and results: The genomic DNA of 43 Candida BSI blood culture samples obtained from Universiti Malaya Medical Centre (UMMC) was isolated, after which species identification was carried out using PCR with ITS-1 and ITS-4 pan-fungal primers in conjunction with CHROMagar™ Candida. The predominant Candida species in the BSI samples is Candida albicans (14 out of 43 isolates). RAPD-PCR on these 14 C. albicans clinical isolates was performed using PST as the arbitrary primer. Data analysis using MEGA found an overall non-relatedness of these 14 clinical isolates [average similarity coefficient (SAB) value 0.733±0.172]. Following in-depth analysis, five of the 14 isolates were observed to be identical (SAB values of 1.00 each), four isolates had SAB values of 0.80-0.99, indicating that they are highly similar, but are non-identical, while five isolates are unrelated (SAB lower than 0.80). This suggests that microevolution might have occurred and that these clinical isolates may possibly belong to different strains. Conclusion, significance and impact of study: A fair degree of genetic heterogeneity was found among the 14 C. albicans isolates from UMMC. To our knowledge, this is the first report on the genetic profiles of C. albicans bloodstream infection isolates from Malaysia, warranting further studies in the possible evolutionary trends within this Candida species in Malaysia. Keywords: Randomly Amplified Polymorphic DNA PCR (RAPD-PCR), Candida albicans, Candida bloodstream infections, Genetic relatedness, DNA fingerprinting
Subject(s)
Candida albicansABSTRACT
A prospective study was conducted on 510 respiratory specimens for the presence of M. tuberculosis detected by direct acid-fast bacilli (AFB) smear examination, culture in the Manual Mycobacteria Growth Indicator Tube (BBL MGIT, Becton-Dickinson) and culture on Lowenstein-Jensen (LJ) medium. From positive BBL MGIT tubes, Ziehl-Neelsen and Gram stains were performed and subcultures were put up on LJ medium. A total of 101 (19.8%) specimens were positive by the BBL MGIT, 60 (11.8%) by primary LJ medium culture, 31 (6.1%) by direct smear examination and 29 (5.7%) by all three methods. Using primary LJ culture as the gold standard, the sensitivity and specifi city of the BBL MGIT were 90% and 89.6% respectively but the sensitivity of AFB smear microscopy was only 48.3%. About half (51.1%) of the BBL MGIT false positives were due to contamination by non-AFB bacteria. The remaining false positives comprised specimens that were AFB microscopy positive but LJ culture negative. Of the AFB isolates obtained on LJ primary and sub-cultures, almost all (93.3%) were identifi ed as Mycobacterium tuberculosis complex. The mean time-to-detection was signifi cantly shorter (p<0.0001) for the BBL MGIT than for LJ culture. For the former, positive results were available within 14 days for both AFB smear-positive and AFB smear-negative specimens. On the average, positive results were obtained 1.8 days earlier for direct AFB smear-positive samples than for AFB smear-negative samples. On the other hand, positive growth on LJ medium appeared after at least 33 days of incubation. These fi ndings suggest that the BBL MGIT system will be a suitable alternative to LJ culture for the routine diagnosis of pulmonary tuberculosis, but a combination of liquid and solid cultures is still required for the highest diagnostic accuracy.
ABSTRACT
Anti-Malassezia furfur monospecific polyclonal antibodies was produced by repeated immunization of rabbit with Malassezia furfur yeast cells mixed with Freud adjuvant. The antibody titres of respective rabbit's serum samples prior to and after each immunization against M. furfur were assayed by indirect immunofluorescence technique using the M. furfur whole yeast antigen fixed in Teflon coated slides. The highest anti-M. furfur antibody titre achieved was 1 in 1280 dilution. At 1:20 dilution, none of the respective serum samples taken at various stages of immunization gave positive immunofluorescent staining against any of the other species of yeasts tested in this study. Anti-M. furfur monospecific polyclonal antibodies produced in rabbit in this study has the potential for diagnostic application in immunohistochemical detection of M. furfur in human tissues.