BACKGROUND:
Laryngoscope blades are in contact with mucous membrance and can pissiblily contaminated with transmissible microgranisms. The cover for the blade of the laryngoscope may be can prevent the cross infection. The aim of this study was to evaluate the effect of use of disposable nylon sheath over laryngoscope blade on bacterial contamination of pharynx and post operative sore throat.

METHODS:
66 patients undergoing general anesthesia were included in this study. In case group (n=32) a translucid nylon cover enclosing the blade of laryngoscope. In control group (n=34) the blade used without cover . Before induction of anesthesia, in both groups the samples from blade, and before induction of anesthesia and 24hr after operation the sample from patients pharynx were obtained and sent for aerobic and anaerobic bacterial culture. Frequency of positive culture and post operative sore throat were determined. The intensity of post operative sore throat was assessed at 24hr after operation using visual analogue scale (VAS). Data were ananlyzed using chi-square, Fisher exact, McNemar and t-tests.

FINDINGS:
The frequency of positive culture of pharynx before induction of anesthesia in case and control groups was 89.3 % and 94.1 % respectively (P>0.05). This frequency was 43.7 % and 61.8 % at 24 hr after operation (P>0.05).
In 6 samples of laryngoscope blade, bacterial culture was positive. The occurence of post operative sore throat in both groups was 62.5% and 52.9% respectively (P>0.05). There were no correlation between pharyngeal cultures and post operative sore throat.

CONCLUSION:
The bacteriological study of laryngoscope blades showed that the routine cleaning and sterilization of blades in our hospital is effective. Laryngoscope blade cover has no effects on bacterial contamination of pharynx and post operative sore throat.

KEY WORDS:
Laryngoscope, Cover, Bacterial Contamination, Pharynx, Sore throat