Microbiological Evaluation of Total and Thermotolerant Coliforms in the Water and Drinking Fountains of a Public School in Gama ‑ Distrito Federal

Abstract

Introduction: Water is the most important natural resource of
the planet and is essential for sustaining the life of all living beings.
However, it can also serve many microorganisms harmful to the human
health.
Objective: To evaluate and identify the presence of total and thermotolerant
coliforms in the water and faucets of drinking fountains
of a school.
Methods: This is a qualitative and quantitative research, which
collected five water samples in test tubes and five samples of smear
in the surface of faucets by means of swabs. The water samples were
evaluated according to Normative Instruction 62 of Brazil’s Ministry
of Agriculture, following a series of 10‑1, 10‑2 e 10‑3 dilutions. These
samples were subjected to the test of presumptive coliforms, which
were inoculated in Sodium Lauryl Sulfate concentrations in single
and double concentrations, and were then incubated at 36 ± 1 º C
for 24/48 hours. The smears of the taps were sown in Petri dishes
on blood agar and MacConkey agar, then incubated at 36 ± 1 º C for
24/48 hours. These dishes were tested for catalase, Gram staining
and coagulase.
Results: None of the analyzed samples presented contamination
by total or thermotolerant coliforms, although the faucet surfaces
were contaminated by Staphylococcus aureus in 25% of the samples,
Staphylococcus sp in 37.5% of the samples and Gram‑Positive Bacillus
in 37.5% of the samples.
Conclusion: All water samples were in conformity with Ordinance
2914/2011 of the Ministry of Health. However, it is important to note
that the faucets did not present satisfactory results as to the presence
of microorganisms, considering that these microorganisms can be
pathogenic to human health.