Objective: A survey of antimicrobial resistance in S. pneumoniae isolates collected from representative geographic regions of Mississippi during two different respiratory seasons was conducted to determine rates and distribution of drug resistance.
Design: A total of 318 S. pneumoniae isolates was collected from July 1999 to March 2000, and 171 isolates were collected from July 2001 to March 2002. The minimum inhibitory concentration for 12 antibiotics was determined by the micro dilution method.
Setting: A total of 28 hospitals through out the state of Mississippi participated in the submission of S. pneumoniae isolates felt to be clinically relevant and reported to the attending physician. Specimens were transported to a central laboratory via state health department courier.
Patient population: Isolates were obtained from hospital inpatients as well as outpatients seen in local clinics.
Main outcome measures: Changes in the percentage of isolates resistant to the tested antibiotics and patient demographics were collected.
Results: Pediatric isolates accounted for 36% and 28%, respectively, in 2000 and 2002. The relative percentage of total respiratory isolates remained for each year. Resistance to penicillin increased in pediatric (58% vs. 71%) and adult (40% vs. 52%) as did resistance to ceftriaxone (pediatric 14% vs. 31%; adult 9% vs. 25%) from 2000 to 2002. The majority of isolates were resistant to multiple antibiotics in both years tested.
Conclusion: The results of this study are comparable to those from other national studies of antimicrobial resistance in S. pneumoniae demonstrating increasing resistance to multiple classes of antibiotics quantitatively and qualitatively.