Distribution of virulence genes and the molecular epidemiology of Streptococcus pyogenes clinical isolates by emm and multilocus sequence typing methods.

BACKGROUND: Streptococcus pyogenes has a variety of virulence factors and the predominant invasive strains differ according to specific emm types and geographical orientation. Although emm typing is commonly used as the gold standard method for the molecular characterisation, multilocus sequence typing (MLST) has become an important tool for comparing the genetic profiles globally. This study aimed to screen selected virulence genes from invasive and non-invasive clinical samples and to characterise the molecular epidemiology by emm typing and MLST methods. MATERIALS AND METHODS: A total of 42 S. pyogenes isolates from invasive and non-invasive samples collected from two different tertiary hospitals were investigated for the distribution of virulence factors and their molecular epidemiology by emm and multilocus sequence typing methods. Detection of five virulence genes (speA, speB, speJ, ssa and sdaB) was performed using multiplex polymerase chain reaction (PCR) using the standard primers and established protocol. Phylogenetic tree branches were constructed from sequence analysis utilised by neighbour joining method generated from seven housekeeping genes using MEGA X software. RESULTS: Multiplex PCR analysis revealed that sdaB/speF (78.6%) and speB (61.9%) were the predominant virulence genes. Regardless of the type of invasiveness, diverse distribution of emm types/subtypes was noted which comprised of 27 different emm types/subtypes. The predominant emm types/subtypes were emm63 and emm18 with each gene accounted for 11.8% whereas 12% for each gene was noted for emm28, emm97.4 and emm91. The MLST revealed that the main sequence type (ST) in invasive samples was ST402 (17.7%) while ST473 and ST318 (12% for each ST) were the major types in non-invasive samples. Out of 18 virulotypes, Virulotype A (five genes, 55.6%) and Virulotype B (two genes, 27.8%) were the major virulotypes found in this study. Phylogenetic analysis indicated the presence of seven different clusters of S. pyogenes. Interestingly, Cluster VI showed that selected emm/ST types such as emm71/ST318 (n=2), emm70.1/ST318 (n=1), emm44/ST31 (n=1) and emm18/ST442 (n=1) have clustered within a common group (Virulotype A) for both hospitals studied. CONCLUSION: The present study showed that group A streptococcci (GAS) are genetically diverse and possess virulence genes regardless of their invasiveness. Majority of the GAS exhibited no restricted pattern of virulotypes except for a few distinct clusters. Therefore, it can be concluded that virulotyping is partially useful for characterising a heterogeneous population of GAS in hospitals.

The importance of using a right test method in diagnosing leptospirosis.

Leptospirosis is a common febrile illness in Malaysia. The disease is caused by pathogenic bacteria called leptospires that are transmitted directly or indirectly from animals to humans via contaminated water or soil. It is a potentially serious but treatable disease. Its symptoms may mimic those of other unrelated febrile illnesses such as dengue, influenza, meningitis, hepatitis or viral haemorrhagic fevers. The spectrum of the disease is extremely wide, ranging from subclinical infection to a severe syndrome of multiorgan infection with high mortality. The diagnosis requires high suspicion with history of exposure to water or environment possibly contaminated with infected animal urine. This is a case of a 13 year-oldgirl with no known medical illness, and a history of exposure to outdoor activities. However, paired sera for leptospirosis serology was not diagnostic. She then developed septic shock on day 14 of illness. But due to high suspicion of leptospirosis, antibiotic therapy was upgraded to ceftriaxone and samples were sent for further testing which revealed that leptospires were detected in the urine, using molecular technique. She improved after treated as leptospirosis.

The importance of using a right test method in diagnosing leptospirosis

@#Leptospirosis is a common febrile illness in Malaysia. The disease is caused by pathogenic bacteria called leptospires that are transmitted directly or indirectly from animals to humans via contaminated water or soil. It is a potentially serious but treatable disease. Its symptoms may mimic those of other unrelated febrile illnesses such as dengue, influenza, meningitis, hepatitis or viral haemorrhagic fevers. The spectrum of the disease is extremely wide, ranging from subclinical infection to a severe syndrome of multiorgan infection with high mortality. The diagnosis requires high suspicion with history of exposure to water or environment possibly contaminated with infected animal urine. This is a case of a 13 year-oldgirl with no known medical illness, and a history of exposure to outdoor activities. However, paired sera for leptospirosis serology was not diagnostic. She then developed septic shock on day 14 of illness. But due to high suspicion of leptospirosis, antibiotic therapy was upgraded to ceftriaxone and samples were sent for further testing which revealed that leptospires were detected in the urine, using molecular technique. She improved after treated as leptospirosis.

Identification of germline alterations in breast cancer predisposition genes among Malaysian breast cancer patients using panel testing.

Although an association between protein-truncating variants and breast cancer risk has been established for 11 genes, only alterations in BRCA1, BRCA2, TP53 and PALB2 have been reported in Asian populations. Given that the age of onset of breast cancer is lower in Asians, it is estimated that inherited predisposition to breast cancer may be more significant. To determine the potential utility of panel testing, we investigated the prevalence of germline alterations in 11 established and 4 likely breast cancer genes in a cross-sectional hospital-based cohort of 108 moderate to high-risk breast cancer patients using targeted next generation sequencing. Twenty patients (19%) were identified to carry deleterious mutations, of whom 13 (12%) were in the BRCA1 or BRCA2, 6 (6%) were in five other known breast cancer predisposition genes and 1 patient had a mutation in both BRCA2 and BARD1. Our study shows that BRCA1 and BRCA2 account for the majority of genetic predisposition to breast cancer in our cohort of Asian women. Although mutations in other known breast cancer genes are found, the functional significance and breast cancer risk have not yet been determined, thus limiting the clinical utility of panel testing in Asian populations.