Susceptibility Pattern of Doxycycline in Comparison to Azithromycin, Cefuroxime and Amoxicillin against Common Isolates: A Retrospective Study Based on Diagnostic Laboratory Data

Introduction: Doxycycline acts against a broad range of gram-positive, gramnegative and 'atypical' bacteria as well as some protozoan pathogens such as malaria. In this era of increasing multidrug-resistance, recycling of old antimicrobials should be considered and need more focus in this domain of research. We, therefore, aimed to assess the antimicrobial susceptibility patterns of commonly isolated pathogens against doxycycline, azithromycin, cefuroxime, and amoxicillin from common clinical specimens by using laboratory-based diagnostic data from western India.

Materials and methods: The non-interventional retrospective study was conducted on secondary data extracted from multi-center diagnostic laboratory based in Mumbai, India. Susceptibility data of bacteria isolated from blood, urine, pus, and sputum were used in the study and culture positive samples were segregated. Antimicrobial susceptibility status of doxycycline was checked and compared with azithromycin, cefuroxime, and amoxicillin. Chi-square tests of significance were carried out to assess significant differences in susceptibility patterns. Association between variables was considered statistically significant if the p-value was <0.05.

Results: Percentage susceptibility of collective bacterial isolates was found to be highest for doxycycline in all four specimens (93.1%). Individual percentage susceptibility was observed to be highest for sputum isolates (97.5%) followed by blood (93.8%), pus (92.7%) and urine (70.0%). The activity of doxycycline was found to be 93.5% for the samples resistant to azithromycin. Doxycycline also showed good susceptibility for the isolates resistant to amoxicillin and cefuroxime which was 75.9% and 64.8%, respectively.

Conclusion: Several bacterial isolates from all four sources were found to be susceptible to Doxycycline. It has an important role in the form of a better alternative of major antimicrobial agents like azithromycin, cefuroxime, and amoxicillin against gram-positive cocci. Doxycycline appeared to show better activity against isolates which were resistant to other three antimicrobials.