1.The manual MGIT system for the detection of M tuberculosis in respiratory specimens: an experience in the University Malaya Medical Centre
Fadzilah Mohd Nor ; Kee Peng Ng ; Yun Fong Ngeow
The Malaysian Journal of Pathology 2009;31(2):93-97
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.
2.Genetic relatedness of Candida albicans bloodstream infection clinical isolates in Malaysia
Chhabra-Singh Saranpal ; Pei Pei Chong ; Kee Peng Ng ; Crystale Siew Ying Lim
Malaysian Journal of Microbiology 2015;11(3):294-299
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
Candida albicans
3.Detection of Respiratory Viruses from ARTI Patients by xTAG RVP Fast v2 Assay and Conventional Methods
Chee Sian Kuan ; Su Mei Yew ; Poh Sim Hooi ; Lu Mei Lee ; Kee Peng Ng
Malaysian Journal of Medical Sciences 2017;24(5):33-43
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.
4.Negative cross-reactivity of rabbit anti-Malassezia furfur antibodies with other yeasts.
Kaw Bing Chua ; Shamala Devi ; Kee Peng Ng ; Poh Sim Hooi ; Shiang Ling Na ; Kerk Hsiang Chua
The Malaysian journal of pathology 2005;27(2):123-5
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.
Antibodies
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Upper case emm
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Rabbits
;
Malassezia furfur
;
Immunization
5.Guidance for the clinical management of infants born to mothers with suspected/confirmed COVID-19 in Singapore.
Kee Thai YEO ; Agnihotri BISWAS ; Selina Kah YING HO ; Juin Yee KONG ; Srabani BHARADWAJ ; Amutha CHINNADURAI ; Wai Yan YIP ; Nurli Fadhillah AB LATIFF ; Bin Huey QUEK ; Cheo Lian YEO ; Yvonne Peng MEI NG ; Kenny Teong TAI EE ; Mei Chien CHUA ; Woei Bing POON ; Zubair AMIN
Singapore medical journal 2022;63(9):489-496
In this paper, we provide guidance to clinicians who care for infants born to mothers with suspected/confirmed COVID-19 during this current pandemic. We reviewed available literature and international guidelines based on the following themes: delivery room management; infection control and prevention strategies; neonatal severe acute respiratory syndrome coronavirus 2 testing; breastfeeding and breastmilk feeding; rooming-in of mother-infant; respiratory support precautions; visiting procedures; de-isolation and discharge of infant; outpatient clinic attendance; transport of infant; and training of healthcare staff. This guidance for clinical care was proposed and contextualised for the local setting via consensus by members of this workgroup and was based on evidence available as of 31 July 2020, and may change as new evidence emerges.
Infant, Newborn
;
Pregnancy
;
Female
;
Humans
;
Mothers
;
COVID-19/epidemiology*
;
Singapore/epidemiology*
;
COVID-19 Testing
;
Pandemics/prevention & control*
;
Infectious Disease Transmission, Vertical/prevention & control*
;
Pregnancy Complications, Infectious/prevention & control*