Intrinsic Resistance: A Significant Characteristic in Evaluating Antibiotic Sensitivity Pattern [Letter].

Dear editor

We have read study titled “Antibiotic Susceptibility Pattern and Bacterial Spectrum Among Patients with External Eye Infections at Menelik II Referral Hospital in Addis Ababa, Ethiopia”1 with keen interest for knowing antibiotic profile of organisms causing external eye infection at a referral hospital of Ethiopia as per Clinical and Laboratory standards Institute (CLSI) guidelines.

We would like to add some comments regarding antibiotic susceptibility pattern of isolates which need to be reviewed urgently in this study:

This study reported Providencia stuartii as 100% sensitive (only one strain isolated and tested) to Ampicillin, Gentamicin and Tobramycin whereas P. stuartii is considered intrinsically resistant to several antibiotics including Ampicillin, Gentamicin and Tobramycin.2,3 The bacteria with intrinsic resistance to antibiotic should be reported “Resistant” only.2 Moreover, the intrinsic resistance is highly important as it along with other resistance mechanism may result in poor clinical outcome.4,5

Further, this study reported 16.7% (1 out of 6 strains) resistance in Streptococcus pneumoniae to penicillin. However, CLSI guidelines have not recommended to report penicillin resistant S. pneumoniae strains on the basis of disk diffusion method(s).2

The study was started from January, 2019 but the authors had used CLSI M100 guidelines of 2017. In the modern world of increasing anti-microbial resistance, CLSI updates M100 guidelines on yearly basis introducing variety of antimicrobial combinations against multi-drug and pan-drug resistant isolates. Since the author is dealing with antibiotic susceptibility pattern, so the latest CLSI guidelines must have been used. If still authors want to adhere to old CLSI guidelines then a short explanation in published paper might be of great importance.

However, we thank to the authors to do a highly efficient work on one of the most concerning areas in medical science and making it available to all.