[Importance of the bacterium-host interaction in coagulase-negative staphylococci isolated from neonates]

Neonates represent a high risk population for infections by coagulase-negative staphylococci (CNS). To have a better understanding of these process our purpose was to compare the expected result of the bacterium-host interaction given by the neonates' risks factors and the micro-organisms' virulence factors with the condition of infecting or colonising strain that emerge from the diagnosis on the basis of the clinical symptoms.

We studied 24 neonates who were submitted to an epidemiological control establishing as risk factors: catheters, vesicle sounds, previous surgery and immunodepressed conditions. In the CNS recovered from clinical samples we determined the following virulence factors: synergistic hemolysis, slime production, adherence to Teflon catheters and hydrophobicity.

We found correlation between the clinical diagnosis and the expected result of the bacterium-host interaction in 21 patients (87.5%). Among them, in 8 patients infection didn't occurred in spite of having the micro-organisms 3 from 4 virulence factors since the patients didn't have risk factors.

A microbiological study based entirely on identification and treatment can alter the biological context. It is necessary to understand the bacterium-host interaction for an appropriate comprehension of the bacterial diseases.