Detection of pneumolysin in cerebrospinal fluid for rapid diagnosis of Pneumococcal meningitis.

BACKGROUND & OBJECTIVES: Pneumolysin, a toxin produced by Streptococcus pneumoniae is associated with virulence and is found in all invasive isolates. Its role as a diagnostic tool has recently been exploited. Most of the methods used are based on molecular techniques and are not cost-effective. The present study was undertaken to evaluate a simple, rapid and cost-effective method to detect pneumolysin in CSF as a diagnostic test for pneumococcal meningitis. METHODS: A total of 75 CSF samples from children with presumptive diagnosis of acute pyogenic meningitis or encephalitis were subjected to Gram stain, culture and pneumolysin detection by Cowan 1 staphylococcal protein A co-agglutination technique. RESULTS: Pneumolysin was detected in 26(78.8%) of 33 culture proven CSF samples and 4(9.5%) of 42 culture negative samples. Antigen detection by Co-A had a specificity of 90 per cent and a sensitivity of 79 per cent when compared with culture. Compared to Gram stain, pneumolysin Co-A had a specificity and sensitivity of 91.0 and 92.0 per cent respectively. INTERPRETATION & CONCLUSION: Detection of pneumolysin was found to be a simple, low cost antigen detection assay for rapid diagnosis of pneumococcal meningitis, for routine use in the developing countries.

Pneumolysin in urine: A rapid antigen detection method to diagnose pneumococcal pneumonia in children.

PURPOSE: Etiological diagnosis of pneumococcal pneumonia is difficult in small children in whom blood culture cannot be done or who have already been started on antibiotics. A simple technique which can be applied at the bedside or in the outpatient department may help in obviating this problem. Detection of pneumolysin, a product of invasive pneumococci is being exploited as a diagnostic tool. METHODS: An attempt was made to detect this protein in urine of seventy children, clinically suspected and radiologically diagnosed cases of pneumonia. Seventy age and sex matched controls were included in the study. Purified pneumolysin was prepared from clinical isolates of invasive pneumococcal infections. This was used to raise polyclonal antisera in rabbits. The antisera was used to sensitise Cowan 1 Staphylococcus aureus (CoA). A slide agglutination was performed with 25 microL urine and equal quantity of the reagent. RESULTS: Results were compared with CoA reagent sensitised with antisera raised against a genetically derived pneumolysoid and capsular polysaccharide for antigen detection in the urine. Pneumolysin could be detected in 42.9% (30/70) urine samples from cases with pneumonia by the genetically derived antigen and in 37.1% samples by the in house prepared antigen, in contrast to 2.1% in healthy controls and 4.2% in children with infections other than pneumonia. The result was statistically significant. Detection of pneumolysin was slightly better than detection of capsular polysaccharide antigen in urine although the result was not statistically significant. Blood culture proved to be positive in only 29.5% cases. CONCLUSIONS: Pneumolysin detection in urine showed promising results and was found to be simple and rapid. It will help in quickening the diagnosis of pneumococcal pneumonia.

Cost-effective method of serotyping streptococcus pneumoniae using staphylococcal co-agglutination.

Typing of Streptococcus pneumoniae to determine the serotype prevalence has paved the way for polyvalent vaccines to prevent invasive pneumococcal infection. Variation of serotype prevalence in different geographical areas necessitates typing of strains from these areas for effective vaccine protection. High cost of antisera very often is a hindering factor in undertaking this exercise. We have tried to evaluate typing by co-agglutination to reduce cost. Clinical isolates of S.pneumoniae from Pondicherry and surrounding Tamil Nadu were serotyped using antisera coated Staphylococcus aureus Cowan I strain and compared with standard quellung reaction. There was hundred percent correlation. By this method we could determine the serotypes causing invasive infections in this area. A commercially available Pneumotest kit was used as source of type specific antisera. Serotype 1 was found to be the major isolate (20.1%) by both the tests. Twenty-four isolates (13%) belonged to the nonvaccine types. Rest of the isolates was made up by serotypes 6, 5, 19, 23 and 12. Co-agglutination method was found to be a simple rapid and economical technique. Ten milliliters of the reagent could be made, using 0.1 ml of standard antisera. Shelf life was found to be six months at 40C.

Serotype distribution & antimicrobial resistance in Streptococcus pneumoniae causing invasive & other infections in south India.

BACKGROUND & OBJECTIVES: Streptococcus pneumoniae continues to be a major cause of morbidity and mortality in developing countries. The emerging resistance to some common antibiotics compounds the problem. There arises a need to monitor the resistance pattern and map serotype distribution in different geographic locations. The present study was undertaken to determine the serotype prevalence and antibiotic susceptibility of clinically significant S. pneumoniae isolated from a tertiary care hospital in south India. METHODS: A total of 150 clinical isolates from invasive and other clinically significant pneumococcal infections were serotyped and screened for susceptibility to commonly used antibiotics by standard and modified laboratory procedures. RESULTS: Majority (59.3%) of the isolates belonged to one or other of the serotypes 1, 6, 19, 5, 23 and 7. Serotype 1 was the commonest isolate from patients of meningitis and empyema followed by pneumonia. Nineteen isolates (12.6%) were nonvaccine type. Eleven (7.3%) isolates were relatively resistant to penicillin (minimum inhibitory concentration was between 0.1 and 1 microgram/ml) and 64 were resistant to one or more antibiotics. Resistance was distributed equally among the predominant serotypes. INTERPRETATION & CONCLUSION: The common serotypes responsible for significant infections were similar to those reported in some other studies from India, with minor variations. Resistance to cotrimoxazole and tetracycline was predominant followed by chloramphenicol. Low level resistance to penicillin was observed but no isolate had absolute resistance. This calls for monitoring of resistance and mapping of serotype distribution from various parts of India.

Throat carriage of pneumococci in healthy school children in the Union Territory of Pondicherry.

BACKGROUND & OBJECTIVES: Colonisation of Streptococcus pneumoniae in the throat is common among children the world over. Little is known about the relationship of nasopharyngeal carriage and invasive disease or the way it spreads within the households and close confines. There is a paucity of data on the colonization of Strep. pneumoniae in the throat of healthy children in India. To determine the prevalence of pneumococcal carriage in school children of urban and rural Pondicherry, a study was undertaken. METHODS: Throat swabs of healthy school-going children between 5-10 yr of age were examined for pneumococcal carriage, by standard bacteriological techniques. RESULTS: A prevalence rate of 24.3 per cent was noted. There was no difference in the carriage rate among the rural children when compared to urban children. No age, sex or geographical predilection of pneumococcal carriage was noted. A statistically significant seasonal variation, however, was seen. Carriage rate increased during the colder months and was found to be the highest in the months of March and November. INTERPRETATION & CONCLUSIONS: Strep. pneumoniae circulates in the community among healthy children. Carriage rate is influenced by seasonal variation.