A potential role for the chest X-ray in the transmission of resistant bacteria in the ICU

Introduction

An investigation of infection control practices used by X-ray technicians during the performance of routine chest X-ray scans in the ICU, transmission of resistant bacteria to the X-ray machine, and the effect of an infection control intervention. Up to 20% of patients acquire infections in the ICU, 44% of which may be transferred on caregivers' hands. Daily routine chest X-ray scans are performed sequentially, presenting the potential for bacterial spread. The degree to which X-ray technicians apply infection control measures, and the extent to which bacteria are transferred, is unknown.

Methods

Compliance with 14 infection control measures was measured covertly during the performance of daily chest X-ray scans. Bacterial surface cultures were taken from the X-ray machines. An educational intervention (informing the technicians about resistant bacteria, machine culture results and correct alcohol and glove use) was instituted. Observations and machine cultures were repeated. The appearance of resistant bacteria in patient cultures was followed.

Results

Infection control practices were compared before and after the intervention. Alcohol hand-rub use before patient contact increased from 12% to 25% of occasions (P = 0.009), from 0% to 62% prior to touching the X-ray machine (P < 0.001) and from 9% to 39% (P < 0.001) before touching the next patient. Glove use also improved significantly.

Resistant Gram-negative bacteria grew in 12/31 (39%) preintervention X-ray machine cultures and 0/29 (0%, P < 0.001) postintervention cultures. Cultures with no bacterial growth increased from 11/31 (33%) to 22/29 (67%, P = 0.002) pre to post intervention.

New occurrences of resistant Gram-negative bacteria in clinical cultures decreased from 19 in 68 patients (28%) pre intervention to 8/84 (10%, P = 0.003) post intervention.

Conclusion

Resistant Gram-negative bacteria are found frequently on the X-ray machine, probably being transferred on technicians' hands. This represents the potential for patient-to-patient bacteria transfer. A simple infection control intervention decreases X-ray machine contamination and is associated with a decrease in the appearance of resistant bacteria in patient cultures, although causality is not proven.