Macrolide Resistance Changes in Clinical Isolates of Streptococcus pyogenes in Kentucky
Major
Biology
Department
Biological Sciences
Degree
Undergraduate
Mentor
Marcia M. Pierce
Mentor Department
Biological Sciences
Recommended Citation
Helton, Hayley L.; Jackson, Robert D.; and Watkins, Marcia, "Macrolide Resistance Changes in Clinical Isolates of Streptococcus pyogenes in Kentucky" (2015). University Presentation Showcase Event. 45.
https://encompass.eku.edu/swps/2015/undergraduate/45
Abstract
Group A streptococcal (GAS) infections are most often caused by the species Streptococcus pyogenes. S. pyogenes may cause symptoms ranging from pharyngitis to life-threatening infections such as necrotizing fasciitis. While penicillin is the preferred treatment, patients that are allergic must rely on alternate drugs, including the macrolides erythromycin and clindamycin. Due to overuse of macrolides there is an increase in macrolide-resistant strains of S. pyogenes. Clinical isolates of S. pyogenes obtained ten years apart from a Lexington, Kentucky hospital in 2004 and again in 2014 were analyzed for resistance to these antibiotics. Those strains that tested positive were then genotyped for the mef (A), erm (A), erm (B), and erm (TR) genes. These genes are the basis of mechanisms that induce macrolide resistance. Isolates from 2004 showed resistance to erythromycin (22% of strains), clindamycin (12%), clarithromycin (20%), and lincomycin (22%). Themef (A) gene was more prevalent than the erm (B, TR) genes in 2004. Isolates from 2014 showed resistance to erythromycin (34% of strains), clindamycin (11%), penicillin (9%), and lincomycin (11%). A two proportion z-test was used to measure if there was a significant difference in resistance to erythromycin, clindamycin, and lincomycin. Based on the results from the z-test, isolates are less resistant to clindamycin and lincomycin in 2014 than they were in 2004. Erythromycin resistance was also greater in 2014 than it was in 2004. Further investigation will include verifying genotypes of remaining resistant isolates from 2004 and 2014.
Presentation format
Poster
Poster Number
43
Macrolide Resistance Changes in Clinical Isolates of Streptococcus pyogenes in Kentucky
Group A streptococcal (GAS) infections are most often caused by the species Streptococcus pyogenes. S. pyogenes may cause symptoms ranging from pharyngitis to life-threatening infections such as necrotizing fasciitis. While penicillin is the preferred treatment, patients that are allergic must rely on alternate drugs, including the macrolides erythromycin and clindamycin. Due to overuse of macrolides there is an increase in macrolide-resistant strains of S. pyogenes. Clinical isolates of S. pyogenes obtained ten years apart from a Lexington, Kentucky hospital in 2004 and again in 2014 were analyzed for resistance to these antibiotics. Those strains that tested positive were then genotyped for the mef (A), erm (A), erm (B), and erm (TR) genes. These genes are the basis of mechanisms that induce macrolide resistance. Isolates from 2004 showed resistance to erythromycin (22% of strains), clindamycin (12%), clarithromycin (20%), and lincomycin (22%). Themef (A) gene was more prevalent than the erm (B, TR) genes in 2004. Isolates from 2014 showed resistance to erythromycin (34% of strains), clindamycin (11%), penicillin (9%), and lincomycin (11%). A two proportion z-test was used to measure if there was a significant difference in resistance to erythromycin, clindamycin, and lincomycin. Based on the results from the z-test, isolates are less resistant to clindamycin and lincomycin in 2014 than they were in 2004. Erythromycin resistance was also greater in 2014 than it was in 2004. Further investigation will include verifying genotypes of remaining resistant isolates from 2004 and 2014.
