[The effect of surgical antibiotic prophylaxis and the timing of its administration on the risk of surgical wound infection].
BACKGROUND
Clinical trials have demonstrated the efficacy of surgical prophylaxis (SP). Nevertheless, how the timing of antibiotic administration influences the risk of infection in clinical praxis has scarcely been studied. In this study an assessment was made of whether the non administration of antibiotic, or its administration longer than 2 hours preoperatively, or only postoperatively, are associated with a higher rate of infection of the surgical wound (SWI) compared with antibiotic administration within the two hours prior to surgery in our setting.


METHODS
Observational, longitudinal, pseudoretrospective study. It included 2,483 patients undergoing surgery in 1992, with clean-contaminated, contaminated and clean with prophylaxis indication, and without previous infection surgeries. Information on variables potentially associated with SWI and incidence of infection was monitored. A multivariate analysis was made by means of the logistic regression method to evaluate the association of prophylaxis and time of administration, controlling for the remaining variables.


RESULTS
754 patients received appropriate prophylaxis (within 2 hours prior to surgery); 28 of these patients (3.7%) developed SWI. Twenty-four of the 107 who received prophylaxis longer than 2 hours prior to surgery developed infection (22.4%; p < 0.001 compared with the first group; OD: 7.5, 95% CI: 3.94-14.1); in the group of patients non receiving preintervention doses 94 patients developed infection (7.7%; p = 0.001; OR: 2.16, 95% IC: 1.38-3.41). Among patients who did not receive prophylaxis 24 infections were detected (6%; p = 0.10; OR: 1.66, 95% CI: 0.91-2.99). In the multivariate analysis the administration of prophylaxis longer than 2 hours prior to surgery or postoperatively was confirmed to be associated with a higher SWI rate, as in the non-administration situation, controlling for the remaining variables (OR for longer than 2 hours: 5.82; for postoperative administration: 3.23, and for non-administration: 2.68).


CONCLUSIONS
The administration of SP is inappropriate in a high percentage of cases. The administration of SP within the 2 hours prior to surgery reduces the risk of SWI, compared with the administration 2 hours or longer prior to intervention or only postoperatively.
Servicio de Medicina Preventiva, Hospital Virgen de la Salud, Toledo.
E
E
Muñoz Platón
J A
JA
Jiménez Antolín
S
S
Brea Zubigaray
P
P
Bravo García
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019072:Antibiotic Prophylaxis / Q000706:statistics & numerical data; D002648:Child; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D013530:Surgical Wound Infection / Q000453:epidemiology / Q000517:prevention & control*; D013997:Time Factors
Efecto de la profilaxis quirúrgica antibiótica y su tiempo de administración sobre el riesgo de infección de herida quirúrgica.