Benefit of systematic selection of pairs of cases matched by surgical specialty for surveillance of bacterial transmission in operating rooms

Abstract

Bacterial transmission within and between successive surgical cases occurs in operating rooms (ORs), often includes anesthesia equipment as a reservoir, and can be monitored by collecting samples and identifying bacteria by genetic testing. We evaluated how tochoose cases for active surveillance to quantify the effectiveness of interventions in 2groups ofORs (eg, rooms with germicidal lighting vs those without). Data were from a 7 OR single-specialty gastrointestinal endoscopy suite and from atypical 8OR multispecialty surgical suite. At the multispecialty hospital, 40.3% (SE 1.2%) of the total number of cases could be used for surveillance (ie, followed by another case of the same specialty and matched with a corresponding pair of cases from the other OR group). Random selection obtained fewer matched pairs than deliberate selection: mean ratio of random/deliberate = 0.64 (0.01) for the single-specialty and 0.51 (0.02) for the multispecialty suite (P<.001). The efficiency of sampling to obtain pairs of successive surgical cases of the same specialty isimpaired markedly by randomly selecting pairs ofcases (or using convenience sampling) as compared to choosing pairs deliberately. This is important because the number ofcases that can be suitably used for surveillance of bacterial transmission will typically be less than one-half the total case number.