Making Antibiotic Choices: Formula Derivation and Usage in the Rational Selection of Antibiotics in the Empirical Treatment of Infections

Purpose: To develop mathematical formulae to aid the selection of antibiotics most appropriate in the empirical treatment of infections. Methods: Formulae quantifying the characteristics of antibiotics with regard to their cost and activity against associated bacterial isolates of given infections were derived from probability laws. Data from records of culture sensitivity test results were compiled and analysed to ascertain bacterial pathogen associations with infections and their sensitivities to prescribed antibiotics. Applicability of derived formulae was demonstrated in the rational selection of antibiotics most appropriate in the empirical treatment of urinary tract infections (UTIs) in selected hospitals in Lesotho. Results: Escherichia. coli, followed by Klebsiella spp, Proteus spp, non-haemolytic Streptococci, Streptococcus pyogenes and then, Pseudomonas spp were identified as the most common uropathogens at the hospitals studied. Two mathematical formulae were derived and used in quantifying activity and cost characteristics of prescribed antibiotics. Cefotaxime, followed by ciprofloxacin - were considered most appropriate for use in treating UTIs empirically among inpatients of the hospitals. Conclusion: Quantifying and using procedurally antibacterial activities and cost characteristics of antibiotics provides a suitable means of making antibiotic choices in the empirical treatment of infections.