Effectiveness of Minocycline in Multidrug Resistance Gram Negative Bacilli: A Cross-sectional Study

Introduction: Antibiotic resistance is a global public health threat and remains a challenge for the physicians. Due to increased incidence of resistance to the commonly prescribed antibiotics, a newer drug or a re-emerge of an older class of antibiotic will be a choice of treatment of the Multidrug Resistant (MDR) organisms.

Aim: To determine the effectiveness of minocycline in MDR gram negative bacterial isolates by determining its Minimum Inhibitory Concentration (MIC) and to compare its effectiveness with imipenem and meropenem.

Materials and Methods: A cross-sectional periodical study was conducted during May 2016 to May 2017 using 150 non repetitive MDR gram negative bacterial isolates recovered from various clinical specimens sent to Central Laboratory, Department of Microbiology, Sri Ramachandra Medical College and Research Institute, SRIHER, Porur, Chennai, India. All the isolates were subjected for antibiotic susceptibility testing by disc diffusion method for the routine antibiotics and MIC determination by Epsilometry test (E-strip) for minocycline and meropenem and interpreted as per Clinical and Laboratory Standards Institute (CLSI) guidelines 2016. Statistical analysis was calculated with Open Epi using two by two table version 3.01.

Results: Out of the 150 study isolates minocycline was susceptible in 105 (70%) followed by imipenem and meropenem both susceptible for isolates 94 (62.7%). Minocycline was also susceptible among the 79 (84%) out of 94 of meropenem susceptible strains with a statistically significant p-value of <0.05. Similarly 26 (46.4%) out of 56 of meropenem resistant strains were susceptible for minocycline which was also statistically significant with a p-value <0.05.

Conclusion: Considering the cost of treatment with colistin which is the choice of treatment for carbapenemase producing gram negative bacteria’s, minocycline can be considered as it is cheaper and less toxic. The possibility to switch from injectable to oral formulation is also possible with minocycline and so can also be considered as an alternative for colistin in such conditions.