Assessment of cleanliness of blood pressure cuffs in hospitals using atp bioluminescence detection device and microbial cultures

Background: Blood pressure cuffs (BPC) are among the commonest reusable medical equipments used in hospitals. Therefore, there is a considerable concern regarding the potential for these cuffs to transmit HCAI between patients. BPC are frequently contaminated with skin flora and occasionally with pathogens and may lead to increase the risk of HCAI. This risk of cross contamination and possible HCAI could be decreased by using single-patient use products, such as a protective cover for sphygmomanometer cuffs.

Objective: To evaluate levels of contamination of the blood pressure cuff: hooks, loops (Velcro fastners) and cuff cover (inner aspect) & To determine the correlation between ATP bioluminescence and microbial cultures

Methods: BPC on all adult wards in a 450-bedded District General Hospital were tested to determine the level of contamination using ATP bioluminescence detections device and conventional microbiological testing. ATP bioluminescence system measures the amount of ATP as a surrogate marker of contamination. 3 BPC surfaces were randomly sampled: hooks, loops (Vecro) and inner side (surface that comes in contact the patient’s skin). From each of the above sites duplicate swabs were obtained from a 10cm² area. One of the swabs was used to determine the amount of ATP (expressed as Reactive Light Units), the other swab was vortexed in saline, and serial dilutions were cultured on blood agar and incubated at 37C in air for 24 hours. The colony count was expressed as cfu/ ml.

Results: 111 BPC were sampled and 333 samples were collected for ATP bioluminescence and culture. There was no growth in 240/333 (72%) of the samples One sample (1/333, 0.3%) from a loop from which a mixture of S.aureus and S.epidemidis was isolated, all other samples (92/333, 27.6%) yielded skin flora (S.epidermidis, Micrococcus sp or diphtheroids) or environmental contaminants (Bacillus sp. in one sample).   When comparing the three sample sites cultured, the inner side sample area had the highest number of bacteria (Mean: 4 cfu/ml range: 0-504 cfu/ml). Hooks and loops had similar number of colony forming units (Hooks -Mean 1.4cfu/ml; range: 0-58; Loops: Mean: <1 cfu/ml, range 0-113 cfu/ml) the amount of ATP (RLU) from the samples was generally low (mode: 152 RLU, Median: 366 RLU; Range: 20- 49,233 RLU). There was no correlation between the number of colony forming units and RLU.

Conclusions: In this study, we have demonstrated that a majority of the blood pressure cuffs fail to grow common aerobic bacteria and have little organic contamination as shown by relatively low ATP detected. Although we did not isolate any organisms associated with HCAI, nearly a third of the cuffs yielded skin flora (and in S.aureus in one sample) and some of the cuffs had very high organic contamination suggesting that a potential for transmission of infections and the need for improved cleaning procedures between patients.