Viral and bacterial upper respiratory tract infection in hospital health care workers over time and association with symptoms

Raina MacIntyre, C.; Chughtai, Abrar Ahmad; Zhang, Yi; Seale, Holly; Yang, Peng; Chen, Joshua; Pan, Yang; Zhang, Daitao; Wang, Quanyi

Colonisation is important as this may progress to invasive disease [1] . Bacterial colonisation may be an important source of horizontal spread of infection within the community [1] . Among 170 HCWs with positive bacterial result at baseline, 68 (40%) became negative at the end of the study. Natural clearance of bacteria in asymptomatic and symptomatic subjects has not yet been studied. The rates of bacterial colonisation in symptomatic HCWs were higher than in asymptomatic HCWs, but this was not significant. Bacterial colonisation in the majority of the HCWs resolved without any treatment or development of symptoms. We found 12 cases of CRI developed over 4 weeks, 11 of which had bacterial colonisation at baseline. If bacterial shedding occurs asymptomatically, then a large amount of undetected transmission may be occurring in hospitals. This may be important for bacteria such as pneumococcus, where the transition from carriage to invasive disease is thought to occur soon after acquisition of infection.