Contamination and decontamination of Doppler probes

Nosocomial infection occurs in 2-9% of patients undergoing vascular surgery and can lead to death, amputation or require complex revision surgery. Neck ties, pagers, stethoscopes and Doppler probes have been shown to carry pathogens. We measured bacterial colonisation of Doppler probes on a vascular unit and audited the effect of staff education at reducing this contamination.

Bacteriological culture swabs were taken from hand-held Doppler probes on the vascular surgical ward and clinic. There was no protocol for cleaning the Doppler probes, so manufacturers were contacted for their recommendations. The results of cultures were presented to nursing and medical staff, who were then asked to clean the probes with alcohol wipes after each use. After an interval of 1 week, bacteriological cultures from the same Doppler probes was repeated.

Fifty bacteriological cultures were performed from 10 Doppler probes over a 4-week period. Thirteen (26%) cultures were positive for diphtheroids, coliforms, coagulase-negative staphylococci and skin flora. After staff education, 42 further swabs were taken from the same probes; two positive cultures were obtained with scanty growth of skin flora (chi2 P < 0.05).

Staff education and simple cleaning significantly reduces the contamination of hand-held Doppler probes and may help prevent nosocomial infection.