Norazah Ahmad

Characterization of Shigella sonnei in Malaysia, an increasingly prevalent etiologic agent of local shigellosis cases

BackgroundShigellosis is a major public health concern worldwide, especially in developing countries. It is an acute intestinal infection caused by bacteria of the genus Shigella, with a minimum infective dose as low as 10–100 bacterial cells. Increasing prevalence of Shigella sonnei as the etiologic agent of shigellosis in Malaysia has been reported. As there is limited information on the genetic background of S. sonnei in Malaysia, this study aimed to characterize Malaysian S. sonnei and to evaluate the prospect of using multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) for subtyping of local S. sonnei.MethodsForty non-repeat clinical strains of S. sonnei isolated during the years 1997–2000, and 2007–2009 were studied. The strains were isolated from stools of patients in different hospitals from different regions in Malaysia. These epidemiologically unrelated strains were characterized using biotyping, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) and MLVA.ResultsThe two biotypes identified in this study were biotype a (n = 29, 73%) and biotype g (n = 11, 27%). All the 40 strains were sensitive to kanamycin, ceftriaxone and ciprofloxacin. Highest resistance rate was observed for streptomycin (67.5%), followed by tetracycline (40%) and trimethoprim-sulfamethoxazole (37.5%). All the S. sonnei biotype g strains had a core resistance type of streptomycin - trimethoprim-sulfamethoxazole - tetracycline whereas the 29 biotype a strains were subtyped into eight resistotypes. All the strains were equally distinguishable by PFGE and MLVA. Overall, PFGE analysis indicated that S. sonnei biotype a strains were genetically more diverse than biotype g strains. Cluster analysis by MLVA was better in grouping the strains according to biotypes, was reflective of the epidemiological information and was equally discriminative as PFGE.ConclusionsThe S. sonnei strains circulating in Malaysia throughout the period studied were derived from different clones given their heterogeneous nature. MLVA based on seven selected VNTR loci was rapid, reproducible and highly discriminative and therefore may complement PFGE for routine subtyping of S. sonnei.

The In Vitro Antibiotic Susceptibility of Malaysian Isolates of Burkholderia pseudomallei

Acute melioidosis may present as localised or septicaemic infections and can be fatal if left untreated. Burkholderia pseudomallei resistant to antibiotics used for the treatment of melioidosis had been reported. The aim of this study was to determine the in vitro antibiotic susceptibility patterns of Burkholderia pseudomallei isolated in Malaysia to a panel of antibiotics used for the treatment of melioidosis and also to potential alternative antibiotics such as tigecycline, ampicillin/sulbactam, and piperacillin/tazobactam. A total of 170 Burkholderia pseudomallei isolates were subjected to minimum inhibitory concentration determination using E-test method to eleven antibiotics. All isolates were sensitive to meropenem and piperacillin/tazobactam. For ceftazidime, imipenem, amoxicillin/clavulanic acid, and doxycycline resistance was observed in 1 isolate (0.6%) for each of the antibiotics. Trimethoprim/sulfamethoxazole resistance was observed in 17 (10%) isolates. For other antibiotics, ampicillin/sulbactam, chloramphenicol, tigecycline, and ciprofloxacin resistance were observed in 1 (0.6%), 6 (3.5%), 60 (35.3%) and 98 (57.7%) isolates respectively. One isolate B170/06 exhibited resistance to 4 antibiotics, namely, ciprofloxacin, chloramphenicol, trimethoprim/sulfamethoxazole, and tigecycline. In conclusion, the Malaysian isolates were highly susceptible to the current antibiotics used in the treatment of melioidosis in Malaysia. Multiple resistances to the antibiotics used in the maintenance therapy are the cause for a concern.

Identification of Brucella spp. isolated from human brucellosis in Malaysia using high-resolution melt (HRM) analysis

Molecular approaches have been investigated to overcome difficulties in identification and differentiation of Brucella spp. using conventional phenotypic methods. In this study, high-resolution melt (HRM) analysis was used for rapid identification and differentiation of members of Brucella genus. A total of 41 Brucella spp. isolates from human brucellosis were subjected to HRM analysis using 4 sets of primers, which identified 40 isolates as Brucella melitensis and 1 as Brucella canis. The technique utilized low DNA concentration and was highly reproducible. The assay is shown to be a useful diagnostic tool, which can rapidly differentiate Brucella up to species level.

Identification and In Vitro Antimicrobial Susceptibility of Brucella Species Isolated from Human Brucellosis

Brucellosis is a world-wide zoonotic disease with a major impact on the public health. Due to the high risk of laboratory acquired infection, limited laboratory investigations were performed on this organism, including detailed identification and susceptibility study. Brucella melitensis is the commonest aetiological agent for human brucellosis in this region. The in vitro susceptibility pattern against selected antimicrobial agents was assessed using E-test. All isolates were noted to be sensitive to all the antimicrobial agents tested except for rifampicin where elevated MIC > 1 μg/mL was noted in 30 out of 41 isolates tested.

In-house ELISA screening using a locally-isolated Leptospira in Malaysia: determination of its cut-off points

BackgroundLeptospirosis is a zoonotic disease caused by Leptospira species and is distributed globally. Microscopic agglutination test (MAT) is the serological ‘gold standard’ for diagnosis of leptospirosis but it is time-consuming and labour-intensive. An alternative serological method that is rapid, sensitive and specific is important for early treatment to reduce morbidity and mortality. The use of local Leptospira isolation may improve the sensitivity and specificity of the test because it may varies from one geographical region to another region. The objective of this study was to determine the sensitivity, specificity and cut-off points for an in-house Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) using a locally isolated Leptospiral strain IMR/175 as the antigen for the detection of anti-Leptospiral IgM.MethodsSerum samples from 270 patients with clinical symptoms of leptospirosis were subjected to the in-house IgM ELISA, MAT and Leptospirosis rapid test. The optimal cut-off values for positivity and negativity of the IgM ELISA were determined by Receiver Operating Characteristic curves and mean ± 2 standard deviation (SD) analyses of the ELISA values.ResultsThe area under the curve (AUC) which indicates the diagnostic performance of the in-house IgM ELISA was 0.953 (95% Confidence Interval, CI: 0.928, 0.978). The sensitivity and specificity of 90.38% and 87.72% respectively were obtained with the cut-off point of 0.55. A higher sensitivity (96.15%) was obtained when the cut-off point was set at 0.45.ConclusionsThe in-house IgM ELISA assay using local Leptospira isolation was shown to be sensitive and may be suitable to use for the serological diagnosis of leptospirosis for our local hospital setting.

Outbreak of Human Brucellosis from Consumption of Raw Goats' Milk in Penang, Malaysia

We report the largest outbreak of brucellosis in Penang, Malaysia. Brucellosis is not endemic in this region. The index case was a 45-year-old goat farm owner presented with 3 weeks of fever, headache, severe lethargy, poor appetite, and excessive sweating. He claimed to have consumed unpasteurized goats milk that he had also sold to the public. Tests were negative for tropical diseases (i.e., dengue fever, malaria, leptospirosis and scrub typhus) and blood culture showed no growth. Based on epidemiological clues, Brucella serology was ordered and returned positive. Over a period of 1 year, 79 patients who had consumed milk bought from the same farm were diagnosed with brucellosis. Two of these patients were workers on the farm. Four laboratory staff had also contracted the disease presumably through handling of the blood samples. The mean duration from onset of symptoms to diagnosis was 53 days with a maximum duration of 210 days. A combination treatment of rifampin and doxycycline for 6 weeks was the first line of treatment in 90.5% of patients. One-third of the patients had sequelae after recovering and 21% had a relapse. We highlight the importance of Brucellosis as a differential diagnosis when a patient has unexplained chronic fever.

First Draft Genome Sequences of Malaysian Clinical Isolates of Corynebacterium diphtheriae

ABSTRACT Corynebacterium diphtheriae has caused multiple isolated diphtheria cases in Malaysia over the years. Here, we report the first draft genome sequences of 15 Malaysia C. diphtheriae clinical isolates collected from the years 1981 to 2016.

First Two Cases of Fungal Infections Associated with Multi-drug Resistant Yeast, Fereydounia khargensis

Abstract The number of new fungal pathogens is increasing due to growing population of immunocompromised patients and advanced identification techniques. Fereydounia khargensis is a yeast and was first described in 2014 from environmental samples. As far as we know, this is the first report of human infections associated with F. khargensis. The yeasts were isolated from blood of a HIV-positive patient and pleural fluid of chronic renal failure patient. Amplification and sequencing of the internal transcribed spacer and the large subunit regions confirmed the identity of the isolates. Both isolates showed multi-drug resistance to antifungal agents tested.

Community-acquired methicillin-resistant Staphylococcus auereus in a Malaysian tertiary centre in year 2009

Community-Acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is a pathogen recognized to be distinct from hospital-acquired MRSA phenotypically and genotypically. We aimed to identify CA-MRSA cases in UKMMC, their antibiotic susceptibility patterns and genotypic characteristics.

First isolation of Candida wangnamkhiaoensis from the blood of immunocompromised paediatric patient

Candida wangnamkhiaoensis is a species clustered under the Hyphopichia clade has not ever been isolated from any clinical specimens. To the best of our knowledge, this is the first report of C. wangnamkhiaoensis associated with fungaemia in immunocompromised paediatric patient. The isolate was assigned a strain name as UZ1679/14, in which the identification was confirmed by a polymerase chain reaction‐sequencing of the internal transcribed spacer (ITS) and large subunit (LSU) regions of the rRNA gene. Antifungal susceptibility pattern showed that the isolate was sensitive to anidulafungin, caspofungin, fluconazole and voriconazole. The patient clinically improved after the antifungal treatment with caspofungin.