Streptococcus pneumoniae is responsible for many community infections, with the main ones being pneumonia and meningitis. Pneumococcus has developed increased resistance to multiple classes of antibiotics. Developing countries face significant problems of antimicrobial resistance with poor diagnostic facilities, unauthorized sale of antimicrobials, lack of appropriate functioning drug regulatory mechanisms, and non-human use of antimicrobials such as in animal production [13, 14]. In this work, we investigated the antimicrobial resistance profile and MDR pattern of S. pneumoniae from clinical isolates in two regions in Ethiopia. Currently, the antibiotic resistance patterns of S. pneumoniae isolates vary widely from one country to another, but many studies are reporting a high frequency of antimicrobial resistance among pneumococcal isolates.
In the present study, the resistance rate of pneumococci to a penicillin (17.5%) was higher than other beta-lactam antibiotics such as cefotaxime (1.8%) and ceftriaxone (1.8%). Cefotaxime and ceftriaxone have a similar group of the spectrum. The resistance rate to penicillin in the present study was higher than studies in Central Africa (< 6%) , Tunisia (1.2%)  and United States (14.8%) , but higher penicillin resistance rates were observed in Taiwan (43.3–73.2%) , Canada (26.1%) , China (88.3%) , Russia (28%) , Nigeria (28%)  and Guinea (21.5%) . The high prevalence of penicillin resistance in this report implies that the use of penicillin for empiric treatment of suspected pneumococcal infection should no longer be recommended. However, cefotaxime and ceftriaxone show very good activities against S. pneumoniae which might be due to their lack of availability and high cost compared to commonly used penicillin.
The overall resistance rate of S. pneumoniae to erythromycin, clindamycin, tetracycline, chloramphenicol, and trimethoprim/sulfamethoxazole was 59.6%, 17.5%, 38.6%, 17.5%, and 24.6%, respectively. The rate of resistance to erythromycin was 59.6%. This was lower than in studies done in Canada (100%)  and China (95.2%) , but higher than in Russia (26%) , Mozambique (23.6%)  and Pakistan (up to 29.7%) . Seventeen and a half percent (17.5%) isolates were resistant to clindamycin. Higher clindamycin resistance rates were observed in Canada (40.6%)  and China (95.8%) . In addition, 38.6% of our isolates were resistant to tetracycline, which is lower than studies in China (93.6%)  and Nigeria (73.5%) . Furthermore, the resistance rate to trimethoprim/sulfamethoxazole was 24.6% in our study. Higher resistance rates were reported in Central Africa (up to 69%) , Canada (34.5%) , China (66.7%) , Russia (57%) , Nigeria (96.2%)  and Pakistan (86.6%) . In addition, 17.5% of our strains were resistant to chloramphenicol, which is comparable to 18.9% in Central Africa , but lower than in Niger where up to 60% was reported .
These differences in antimicrobial resistance may be explained by differences in the source of the isolates, geographical variability, high prevalence of HIV infection, and antibiotics usage. Higher rates of antibiotic resistance have been linked to high antimicrobial consuming countries . In Ethiopia, antibiotics can be bought without a prescription and this probably leads to overuse and misuse of antibiotics which can promote the widespread antibiotic resistance strain in the area .
The emergence of MDR S. pneumoniae isolates has been a worldwide public health concern for several years. In this study, we demonstrated that penicillin-resistant S. pneumoniae strains were also resistant to erythromycin, tetracycline, and clindamycin (10.5%, 10.5%, and 7% of isolates, respectively). Erythromycin resistant S. pneumoniae strains were resistant to tetracycline, clindamycin, and chloramphenicol (33.3%, 17.5%, and 15.8% of isolates, respectively).
The most common MDR phenotype was resistance to penicillin, erythromycin, tetracycline, and clindamycin, detected in 33.3% of the total isolates. Such MDR rates were higher than those observed in China (21.4%) , Russia (22%)  and Portugal (26%) . However, it was lower than studies reported from Tunisia (96.5%) , Nigeria (53.8%)  and China (99.4%) . Moreover, the results reveal a common pattern of co-resistance to penicillin, erythromycin, clindamycin, and tetracycline. The empirical treatment of pneumococcal infections, especially invasive infections, often requires a combination of two or more antibiotics and longer durations. These conditions inevitably lead to the initiation of high or multidrug resistance among patients with infections.