Is screening of patients for Pseudomonas aeruginosa groin/rectal carriage useful in identifying those at risk of bacteraemia in haematology and other high-risk clinical settings?

Background

Pseudomonas aeruginosa is a leading cause of healthcare-associated infections in patients exposed to hospital waters. A rising incidence of P. aeruginosa bacteraemia at our tertiary teaching hospital prompted investigation.

Aim

Microbiological screening at patient admission to support early identification of acquisition.

Methods

A 41-bed haematology ward (800-bed teaching-hospital, London) was surveyed between January 24^th, 2020 and May 13^th, 2020. Concurrent rectal and groin swabs were collected in duplicate upon admission weekly. Results were compared with historical shower, drain, and tap water contamination data.

Findings

A total of 606 groin/rectal swabs were collected from 154 patients; 61 female and 93 male. Six out of 154 patients admitted (3.9%) were positive for P. aeruginosa. Two patients (1.3%; 95% confidence interval (CI): 0.16 to 4.6) were colonized at admission while four patients (2.6%; CI: 0.7 to 6.5) became colonized by 33 days (interquartile range: 13 to 54) of stay. Concurrent duplicate sampling yielded both positive and negative results in all colonized patient-cases. One patient subsequently developed P. aeruginosa bacteraemia. Shower water and corresponding drains from the four patient rooms where P. aeruginosa was acquired were heavily contaminated (>300 cfu/100 mL) with P. aeruginosa 265 days (median; range: 247–283) before patient admission.

Conclusion

Rectal/groin swab-screening at admission to hospital might be valuable for early detection of patient colonization but it is intrusive, resource-demanding, and yield may be low. In high-risk settings, enhanced environmental monitoring, decontamination of surfaces and drains, and point-of-use filter-barriers is recommended, especially if expected duration of stay exceeds 30 days.