Evaluating Minimum Inhibitory Concentration Values of Levofloxacin and Azithromycin on Haemophilus Influenzae

Background: Community Acquired Pneumonia (CAP) is leading cause of morbidity and mortality in all age groups globally. 4 million cases of Community Acquired Pneumonia occur annually. Haemophilus influenzae is a causative organism of CAP. Empirical treatment with antibiotics like levofloxacin and azithromycin is recommended in these cases.

Objectives: This study was conducted to evaluate the minimum inhibitory concentration of levofloxacin and azithromycin in H. influenzae isolates from respiratory specimens.

Design: Minimum inhibitory concentrations of levofloxacin and azithromycin in 40 clinically significant H.influenzaeisolates were tested using E-test method after the approval of Institutional Ethics committee. The results were analyzed according to 2019 CLSI guidelines.

Result: MIC₅₀ for levofloxacin was 0.008 μg/ml, MIC₉₀ 1.5 μg/ml and the 3 resistant isolates had MIC ranging between 8 and 12 μg/ml. Azithromycin MIC₅₀ was 0.047μg/ml, MIC₉₀ 6.4 μg/ml and 5 resistant isolates had MIC between 6 and 32μg/ml.

Conclusion: The rising MIC of levofloxacin and azithromycin in H.influenzaeemphasizes the need to monitor the antibiotic susceptibility pattern on a regular basis. It is also advisable to restrain the use of fluoroquinolones to make it available for use in the tuberculosis treatment and also to avoid any adverse effects.