H2S as an indicator of water supply vulnerability and health risk in low-resource settings: a prospective cohort study.

In this large-scale longitudinal study conducted in rural Southern India, we compared a presence/absence hydrogen sulfide (H2S) test with quantitative assays for total coliforms and Escherichia coli as measures of water quality, health risk, and water supply vulnerability to microbial contamination. None of the three indicators showed a significant association with child diarrhea. The presence of H2S in a water sample was associated with higher levels of total coliform species that may have included E. coli but that were not restricted to E. coli. In addition, we observed a strong relationship between the percent positive H2S test results and total coliform levels among water source samples (R(2) = 0.87). The consistent relationships between H2S and total coliform levels indicate that presence/absence of H2S tests provide a cost-effective option for assessing both the vulnerability of water supplies to microbial contamination and the results of water quality management and risk mitigation efforts.

Assessment of aerobic bacterial contamination of computer keyboards in a tropical setting.

BACKGROUND: Computers are widely used in healthcare for improved and effective care. Previous published reports have shown microorganisms colonising computer keyboards in some clinical areas. OBJECTIVES: This study was undertaken to measure, compare and characterize the aerobic microorganisms in computer keyboards of hospital and non-hospital settings. METHODOLOGY: Samples were collected from commonly used keys of computers in hospital and non-hospital settings using moistened sterile swabs, inoculated in liquid and solid media, and incubated aerobically at 37 degrees C for 24-48 h. Growth was identified as per standard microbiological procedures. Antibiotic susceptibility was determined for pathogenic strains by Kirby-Bauer method. RESULTS: Growth was seen in all 80 samples (40 from each setting). Staphylococcus aureus was isolated from both settings (hospital: 6 MRSA, 11 MSSA; non-hospital: 4 MRSA, 9 MSSA). Gram-negative bacilli were isolated more frequently from hospital (33%). Statistical analysis showed homogeneity among isolates from computer keyboards in both settings, except for Pseudomonas. CONCLUSION: Isolation of microorganisms from "high-touch" surfaces such as computer keyboards is indicative of the need for awareness on cleaning of such surfaces or disinfection and adequate hand hygiene.