Kian Sing Chan

Emerging Prevalence of Microsporidial Keratitis in Singapore: Epidemiology, Clinical Features, and Management

OBJECTIVE To investigate the incidence and epidemiologic factors involved in the development of microsporidial keratitis. The association of host immune status and clinical pattern, clinical features, and the role of fluoroquinolone monotherapy in treatment are also examined. DESIGN Retrospective, noncomparative case series. PARTICIPANTS All cases (124 patients, 134 eyes) of microsporidial keratitis confirmed with modified trichrome stain positive of corneal scrape over a 4-year period. METHODS Epidemiologic factors were observed. Host immune status with human immunodeficiency virus (HIV) serology and CD4/CD8 analysis was performed when consent was obtained. Visual acuity (VA) and slit-lamp examination throughout the course of keratitis was recorded. Treatment used included topical fluoroquinolones (ciprofloxacin 0.3%, moxifloxacin 0.5%, gatifloxacin 0.5%, levofloxacin 0.5%, or norfloxacin 0.3%) as monotherapy or in combination with topical fumagillin and/or systemic albendazole. Where corneal edema developed, ultrasound corneal pachymetry was recorded. MAIN OUTCOME MEASURES Demographic features and epidemiologic factors, including host immune status. Clinical features and disease course, including the response to different therapeutic regimes. RESULTS Patients ranged in age from 11 to 68 years (mean, 31.9; median, 30) with a male:female ratio of 8:1 (females n = 17 [13.7%]). We performed HIV serology and CD4/CD8 in 45.9% of cases (n = 57); all the cases tested were negative with normal T-cell indices. Epidemiologic factors included soil exposure (50%), contact lens wear (21.1%), and topical steroid treatment (17.1%). The VA on presentation ranged from 20/20 to 20/100 (median, 20/30) with no loss in lines of VA on resolution. Common features were follicular papillary conjunctivitis and coarse punctate epithelial lesions in 3 patterns--diffuse, peripheral, and paracentral--evolving into nummular keratitis before resolution. Resolution occurred in 99% of cases on topical fluoroquinolone monotherapy. Four patients had recurrent disease that resolved with repeat fluoroquinolone or fluoroquinolone/oral albendazole combination. Two new clinical features were identified--diffuse endotheliitis (19.4%) with corneal edema and limbitis. CONCLUSIONS This study identifies an increasing incidence of microsporidial keratitis in Singapore with a strong correlation with prior soil exposure. Diffuse endotheliitis and limbitis have not been described and resolves with topical steroid therapy. Topical fluoroquinolone monotherapy is a valid treatment option.

Rapid Detection of Staphylococcus aureus Panton-Valentine Leukocidin in Clinical Specimens by Enzyme-Linked Immunosorbent Assay and Immunochromatographic Tests

ABSTRACT Staphylococcus aureus strains producing Panton-Valentine leukocidin (PVL) have been epidemiologically linked to specific human infections. To evaluate immunological tests that may be used to diagnose infections with PVL-producing strains, we prospectively collected pus, respiratory tract specimens, and joint fluid specimens from which S. aureus had been isolated in clinical laboratories in six countries. An enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic test (ICT) targeting LukS-PV were performed directly with clinical samples for the detection of PVL. The same tests were applied to S. aureus culture supernatants. The corresponding S. aureus isolates were characterized by PCR for the presence of the PVL locus (lukS-PV and lukF-PV) and the mec A gene. A total of 185 samples from 144 skin infections, 23 bone and joint infections, and 18 lower respiratory tract infections were analyzed. By PCR, 72/185 S. aureus isolates were PVL locus positive (PVL+); 28 of these were also mecA positive. PVL was detected in the supernatants of all PVL+ strains by both ELISA and an ICT, while no signal was observed with PVL-negative strains. The PVL concentrations in human clinical samples that grew PVL+ strains ranged from 0 to 399 μg/ml by ELISA. By the use of 0.015 μg/ml of PVL as a cutoff value, PVL was detected in 65/72 (90%) of the clinical samples by ELISA. The sensitivity and specificity of the ELISA test were 90% and 100%, respectively. By the ICT, PVL was detected in 57/72 (79%) of the samples, and the sensitivity and specificity of ICT were 79% and 100%, respectively. PVL is expressed by S. aureus during human infection, and a PVL-specific ELISA and ICT could be reliable tests for the diagnosis of infections caused by PVL-producing strains.

Comparison of Circulating Tumour Cells and Circulating Cell-Free Epstein-Barr Virus DNA in Patients with Nasopharyngeal Carcinoma Undergoing Radiotherapy

Quantification of Epstein-Barr virus (EBV) cell-free DNA (cfDNA) is commonly used in clinical settings as a circulating biomarker in nasopharyngeal carcinoma (NPC), but there has been no comparison with circulating tumour cells (CTCs). Our study aims to compare the performance of CTC enumeration against EBV cfDNA quantitation through digital PCR (dPCR) and quantitative PCR. 74 plasma samples from 46 NPC patients at baseline and one month after radiotherapy with or without concurrent chemotherapy were analysed. CTCs were captured by microsieve technology and enumerated, while three different methods of EBV cfDNA quantification were applied, including an in-house qPCR assay for BamHI-W fragment, a CE-IVD qPCR assay (Sentosa ®) and a dPCR (Clarity™) assay for Epstein-Barr nuclear antigen 1 (EBNA1). EBV cfDNA quantitation by all workflows showed stronger correlation with clinical stage, radiological response and overall survival in comparison with CTC enumeration. The highest detection rate of EBV cfDNA in pre-treatment samples was seen with the BamHI-W qPCR assay (89%), followed by EBNA1-dPCR (85%) and EBNA1-qPCR (67%) assays. Overall, we show that EBV cfDNA outperforms CTC enumeration in correlation with clinical outcomes of NPC patients undergoing treatment. Techniques such as dPCR and target selection of BamHI-W may improve sensitivity for EBV cfDNA detection.

blaOXA-181–positive Klebsiella pneumoniae, Singapore

To the Editor: Nordmann et al. (1) raised concern over the global spread of carbapenemase-producing Enterobacteriaceae. In their article, they called attention to the oxacillinase-48 (OXA-48) type carbapenemases because bacteria that produce these enzymes do not have a distinctive antimicrobial drug susceptibility profile, and there is less awareness of this mechanism of carbapenem resistance. We report the recent isolation of blaOXA-181–positive Klebsiella pneumoniae from 2 patients from Bangladesh who were admitted to separate hospitals in Singapore within a short period of each other.

Impact of Smoking and Brain Metastasis on Outcomes of Advanced EGFR Mutation Lung Adenocarcinoma Patients Treated with First Line Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors.

Objectives This purpose of this study was to examine clinical-pathologic factors – particularly smoking and brain metastases – in EGFR mutation positive (M+) lung adenocarcinoma (ADC) to determine their impact on survival in patients treated with first line EGFR TKI. Methods A retrospective review of EGFR mutation reflex testing experience for all ADC diagnosed at a tertiary Asian cancer centre from January 2009 to April 2013. Amongst this cohort, patients with advanced EGFR M+ ADC treated with first line EGFR TKI were identified to determine factors that influence progression free and overall survival. Results 444/742 (59.8%) ADC reflex tested for EGFR mutations were EGFR M+. Amongst never-smokers (n=468), EGFR M+ were found in 74.5% of females and 76.3% of males, and amongst ever smokers (n=283), in 53.3% of females and 35.6% of males. Exon 20 mutations were found more commonly amongst heavy smokers (> 50 pack years and > 20 pack years, Pearson’s chi square p=0.044, and p=0.038 respectively). 211 patients treated with palliative first line TKI had a median PFS and OS of 9.2 and 19.6 months respectively. 26% of patients had brain metastasis at diagnosis. This was significantly detrimental to overall survival (HR 1.85, CI 1.09-3.16, p=0.024) on multivariate analysis. There was no evidence that smoking status had a significant impact on survival. Conclusions The high prevalence of EGFR M+ in our patient population warrants reflex testing regardless of gender and smoking status. Smoking status and dosage did not impact progression free or overall survival in patients treated with first line EGFR TKI. The presence of brain metastasis at diagnosis negatively impacts overall survival.

Arginine catabolic mobile element in methicillin-resistant Staphylococcus aureus (MRSA) clonal group ST239-MRSA-III isolates in Singapore: implications for PCR-based screening tests.

Espedido and coworkers found that up to 38.7% of methicillin-resistant Staphylococcus aureus (MRSA) clonal group ST239-MRSA-III strains in a Sydney hospital carried an arginine catabolic mobile element (ACME) type II variant that inserted between orfX and the staphylococcal cassette chromosome mec

Successful treatment of NDM-1 Klebsiella pneumoniae bacteraemia in a neutropenic patient

Abstract The rapid emergence of novel multidrug-resistant organisms coupled with the slow development of new antibiotics is of great concern. With the discovery of New Delhi metallo-beta-lactamase 1 (NDM-1)-producing Klebsiella pneumoniae, clinicians are faced with problems in the treatment of infections caused by this multidrug-resistant organism. Therapeutic experiences are limited. We share our experience of the successful treatment of a febrile neutropenic patient with NDM-1-producing K. pneumoniae bacteraemia.

Changing molecular epidemiology and high rates of mupirocin resistance among meticillin-resistant Staphylococcus aureus in Singaporean hospitals

A prospective cross-sectional study was performed to determine the continuing shift in the molecular epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in Singapore. In total, 666 MRSA isolates from screening cultures performed between 7 and 20 January 2013 were obtained from all seven public sector hospitals in Singapore and were subjected to molecular typing using multilocus variable-number tandem-repeat fingerprinting with confirmatory multilocus sequencing typing for clustered isolates. Isolates were also tested for the presence of the orfX-ACME insert and the high-level mupirocin resistance gene ileS-2. The major circulating clones in Singaporean hospitals were ST22 (63.2%), ST45 (18.9%) and ST239 (10.7%). The orfX-ACME insert was only found in ST239 isolates (31/71, 43.7%), but ileS-2 was found in 207 (31.1%) of the MRSA isolates, varying between 10.0% and 47.8% among the hospitals. In conclusion, the molecular epidemiology of MRSA in Singaporean hospitals has continued to change, with ST45 now replacing ST239 in addition to the ongoing replacement of the latter by ST22. Although a greater proportion of ST239 isolates carry the orfX-ACME insert, the actual clinical impact may be marginal as ST239 MRSA continues to decline. Finally, high-level mupirocin resistance rates are remarkably high in local healthcare-associated MRSA, with implications for MRSA decolonisation and infection prevention. Further surveillance is required to monitor the changing epidemiological trends.

Methicillin-resistant Staphylococcus aureus throat colonization among healthcare workers during an outbreak in Singapore General Hospital.

During an Outbreak in Singapore General Hospital • Author(s): Kian Sing Chan, MBBS; Moi Lin Ling, MBBS, FRCPA, CPHQ; Li Yang Hsu, MBBS, MPH; Ai Ling Tan, MBBS, FRCPA Source: Infection Control and Hospital Epidemiology, Vol. 30, No. 1 (January 2009), pp. 95-97 Published by: The University of Chicago Press on behalf of The Society for Healthcare Epidemiology of America Stable URL: http://www.jstor.org/stable/10.1086/593123 . Accessed: 15/05/2014 21:11

Microsporidian Eye Infection from Outdoor Recreational Activities

Ed. Note: The authors of the published article did not feel that a response was necessary . The minireview in the Journal of Clinical Microbiology by Ramanan et al. ([1][1]) mentions that microsporidia may cause keratitis, particularly in contact lens wearers. We wish to highlight another risk