Analysis of susceptibility data received in state-wide surveillance system

Background:  Antimicrobial resistance has become a serious public health threat recently.  The susceptibility data for antibiotics are useful to medical practice in many ways. 

Objectives: The objectives of this study are: (1) analyze susceptibility data received in state-wide surveillance system; (2) develop antibiogram reports for selected pathogens: Streptococcus Pneumonia, Salmonella, E. Coli (STEC) ; (3) track antibiotic resistance patterns and enhance  antibiotic stewardship.  

Methods: The data were analyzed and presented in accordance with Clinical Laboratory Standards Institute (CLSI) guidelines.  The trend analysis of 5-year antimicrobial resistance data was conducted to track resistance patterns of clinically important microorganisms.

Results:  Aggregated antibiograms for Streptococcus pneumonia, Salmonella, E. Coli (STEC) have been developed using antibiotic data reported to the South Carolina electronic surveillance system. Preliminary trend analysis for selected antibiotics was also carried out. For example, a total of 559 Streptococcus pneumonia cases have antibiotic susceptibility data reported during 2009-2013 with age range from 0 to 99 (median=56). Out of 559 cases, 86 cases (15%) were children under 12 years old. Over the last 5 years, susceptibility to ceftriaxone among Streptococcus pneumonia isolates has been shown to range from 90.37% to 97.06%, clindamycin (82.19%-96.49%), levofloxacin (97.44%-100%) and vancomycin (97%-100%). The denominator is the number of cases with an isolate tested for particular antibiotic. Specifically, a total of 99 (97.06%) isolates were susceptible to ceftriaxone, 33 isolates (52.38%) were resistant to erythromycin, 10 isolates (12.35%) was resistant to penicillin and 7 isolates (10.77%) were resistant to trimethoprim-sulfamethoxazole in 2013. The susceptibility rates for ceftriaxone, levofloxacin and vancomycin stay relatively stable from 2009-2013.

Conclusion: A comprehensive analysis of the susceptibility reported to the South Carolina surveillance system from participating laboratories can promote appropriate use of antibiotics and support the antibiotic stewardship initiative.