Prevalence of gram-negative bacilli in nares and on hands of pharmacy personnel: lack of effect of occupational exposure to antibiotics.

Exposure to antibiotics alters host flora and facilitates colonization by gram-negative bacilli (GNB). This may be important among pharmacy personnel, who have frequent contact with antibiotics and who have sometimes been suspected of inadvertently introducing GNB into parenteral solutions during admixture. We evaluated the risk of colonization by GNB, especially by tribe Klebsielleae (TK) which can proliferate in intravenous fluids, by culturing the hands and nares of 98 pharmacy personnel and 56 control subjects. Four culture surveys of pharmacy personnel yielded mean isolation rates of 79 and 52% for GNB and TK, respectively, from hands and 12 and 6.7% for GNB and TK, respectively, from nares; these rates did not differ significantly from those for control subjects (P greater than 0.1). The frequency with which pharmacy personnel performed antibiotic admixture did not significantly affect the rate of isolation of GNB or TK (P greater than 0.2). No multiresistant strains were isolated, and susceptibility patterns were similar for GNB species from pharmacy personnel and controls. These data indicate that occupational exposure of pharmacy personnel to antibiotics is not of sufficient magnitude to increase rates of nasal colonization or hand contamination with GNB.