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, 2020 and May 13, 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.