ABSTRACT
BACKGROUND & OBJECTIVES: Beta haemolytic streptococci belonging to Lancefield group A, B, C and G cause a wide spectrum of clinical diseases. Hence there is a need for rapid and accurate typing of these strains. The present study was undertaken to evaluate the use of intact cell matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for rapid discrimination between strains of beta haemolytic streptococci. METHODS: Colonies of beta haemolytic streptococci were emulsified with chemical matrix on the sample slide, dried and analyzed by MALDI-TOF-MS. RESULTS: The reproducibility of results for all groups of beta haemolytic streptococci was good and spectra obtained for Lancefield group A, C and G streptococci showed discrimination between the groups on visual comparison. A finer difference in spectrum was observed among group A streptococci isolated from different locations at different periods of time. INTERPRETATION & CONCLUSION: MALDI-TOF-MS may be a potential tool in discriminating between strains of beta haemolytic streptococci, and also in the characterisation of untypable strains of group A streptococci.
Subject(s)
Adolescent , Child , Escherichia coli/metabolism , Humans , Mass Spectrometry/methods , Reproducibility of Results , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Streptococcal Infections/diagnosis , Streptococcus/geneticsABSTRACT
BACKGROUND & OBJECTIVES: There has been a resurgence in the incidence of rheumatic heart disease all over the world and hence surveillance and strain characterization are important. The aim of this study was to screen children in a rural community in south India for throat carriage of group A streptococci and to clinically assess them for signs of rheumatic heart disease. METHODS: Throat swabs were collected from children (5-14 yr) in the village of Orathur, Tamil Nadu and cultured on tryptose blood agar plates. Beta haemolytic streptococci were serogrouped using Streptex kit and biotyped based on their ability to ferment carbohydrates and production of beta-glucuronidase enzyme. Blood samples were also collected and antibodies to streptolysin O demonstrated by latex agglutination tests. All the children were examined by a paediatrician; ECG and echocardiography were performed to assess cardiac function. RESULTS: Eighty of the 310 children included in the study had symptoms of acute respiratory infections; 16 of them grew beta haemolytic streptococci of which 8 belonged to group A (10%). Biotype 4 was most common. Antistreptolysin O (ASO) test did not correlate with culture results. Two of 310 children had rheumatic heart disease but both were culture negative. INTERPRETATION & CONCLUSION: Pharyngeal carriage of group A streptococci was common in this population. The prevalence of rheumatic heart disease was 0.6 per cent. The study emphasizes the need for active surveillance and characterization of GAS isolates.
Subject(s)
Adolescent , Child , Child, Preschool , Humans , India/epidemiology , Pharyngitis/epidemiology , Rural Population , Streptococcal Infections/epidemiology , Streptococcus pyogenes/isolation & purificationABSTRACT
Throat swabs were collected from 310 children aged 5-14 years attending a rural health camp at Orathur near Chennai. Group C Streptococci were isolated from 13/310 (4.19%) cases. Seven out of 13 patients had symptoms of respiratory tract infection. Biochemical characterization of the isolates was done by hemolytic characteristics, Voges-Proskauer test, fermentation of trehalose and sorbitol and hydrolysis of 4-methylumbelliferyl-D-â-glucuronide. Four out of 13 strains were identified as S. equisimilis.