SURVIVAL ON SKIN AND SURFACES OF EPIDEMIC AND NON-EPIDEMIC STRAINS OFENTEROBACTERIA FROM NEONATAL SPECIAL CARE UNITS

It has been suggested that increased ability to survive on the hands o f hospital staff contributes to transmission of certain strains of Gra mnegative bacteria. We tested this hypothesis by comparing the surviva l on fingertips, glass slides and membrane filters of epidemic (M, maj or) and matched non-epidemic (S, sporadic) faecal strains of Escherich ia coli (n=13 vs. 13) and Klebsiella spp. (n=19 vs. 19) found among 10 66 neonates in 25 special care units (SCUs). The time to 50% killing a t 22 degrees C in air was longer for E. coli than for Klebsiella spp. both on human skin (median 6 vs. 2 min P<0.001) and glass surfaces (15 vs. 8 min P<0.001). On the other hand, Klebsiella spp. were superior to E. coli in long-term survival tests on membrane filters expressed a s the minimum inoculum still yielding growth after 10 days exposure at 22 degrees C in air (10(5) vs. 10(8) bacteria P<0.001). Despite a lar ge Variation in survival times between individual strains no differenc es between M strains and S strains were observed in any of the three t ests. This indicates that bacterial properties other than survival on surfaces contribute to the increased capacity for transmission of cert ain strains of enterobacteria in SCUs.