Antibiotic susceptibility patterns of community- and hospital-acquired Staphylococcus aureus and Escherichia coli in Estonia

This study compares the susceptibility patterns of Staphylococcus aureus an d Escherichia coli isolated from patients with hospital-acquired and outpat ient infections. A total of 902 isolates of S. aureus and 1,114 of E. coli were collected in five different Estonian medical centers between January 1 997 and November 1997. Strains were grouped into two different categories, depending on whether they had been obtained from inpatients or outpatients. Compared to S. aureus strains isolated from inpatients, the strains from o utpatients were significantly more resistant to erythromycin (25.3% vs. 17. 9%), tetracycline (33.5% vs. 22.4%) and trimethoprim-sulfamethoxazole (13.9 % vs. 7.9%). Thc overall prevalence of oxacillin-resistant S, aureus was 10 .4%, with no significant differences noted between isolates recovered from inpatients and outpatients. In the case of E. coli, significantly more isol ates from inpatients (42.8%) than from outpatients (34.4%) were ampicillin- resistant. Inpatient isolates of E. coli were also more resistant to cefota xime (9.3%) and nitrofurantoin (11.2%) than outpatient strains (0% and 3.1% , respectively). Analysis showed remarkable co-resistance among both inpati ent and outpatient strains of S. aureus and E. coli. Multiple resistant S. aureus and E. coli strains represented 15.1% and 17.3%, respectively of the organisms examined in this study. With respect to E. coli, significantly m ore multiresistant isolates were found in inpatient than outpatient isolate s (20.4% vs. 8.9%). Our results indicate that the distinction between commu nity-acquired and hospital infections due to S. aureus and E. coli may not be valid in Estonia.