The growth of a variety of commonly encountered bacterial pathogens in several commercially available intravenous infusion fluids was studied. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter aerogenes, Mima polymorpha. Staphylococcus aureus, and Staphylococcus epidermidis in concentrations of 104 – 105 colony-forming units/ml were placed in commercially available solutions of 0.9% sodium chloride, Ringer’s lactate, dextrose 5% in Ringer’s lactate, and dextrose 5% in water. The number of viable microorganisms was determined at 24, 48, 72 and 96 hours and examined at both 23 C and 37 C. Populations of gram-negative bacilli generally increased by two logs in 24 to 48 hours, both at 23 and 37 C, while gram-positive cocci remained stationary or died off. Tonicity, pH and available nutrients appeared to play major roles in survival and growth, while temperature was less important. Dextrose 5% in water appeared to be the most hostile to bacterial growth, while 0.9% sodium chloride. Ringer’s lactate and dextrose 5% in Ringer’s lactate appeared to be more conducive to growth. In the event of contamination, it is concluded that physicians and pharmacists should expect to encounter primarily gram-negative bacilli; by 48 hours, considerable concentrations of contaminating bacteria can be expected; and despite bacteria concentrations of 106 colony-forming units/ml, no turbidity of fluid will be noted.
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