Oral Presentation 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

Antibiotic susceptibility profiles of Streptococcus pyogenes isolated from invasive and non-invasive infections in a low-resourced setting:  Findings from the AFROStrep Study (#61)

Kimona Rampersadh 1 , Clinton Moodley 2 , Kelin Engel 1 , Taariq Salie 1 , Liesl J Zuhlke 3 4 , James B Dale 5 , Mark E Engel 1
  1. AFROStrep Research Initiative, Department of Medicine, University of Cape Town & Groote Schuur Hospital, Cape Town, South Africa
  2. Division of Medical Microbiology, University of Cape Town, Cape Town, South Africa
  3. Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
  4. Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital and University of Cape Town, Cape Town, South Africa
  5. Division of Infectious Diseases, University of Tennessee Health Science Center, Tennessee, USA

Background
Streptococcus pyogenes (group A Streptococcus) causes a wide variety of uncomplicated and serious life-threatening infections, as well as the post-infectious immune complications of acute rheumatic fever and rheumatic heart disease. Fluctuating trends in the antibiotic resistance patterns of this organism have been reported worldwide. The present study aimed to evaluate the antibiotic susceptibility profiles of GAS isolated from invasive and non-invasive infections from hospitals in Cape Town, South Africa.

Methods 
We selected 60 non-duplicated GAS isolates (invasive =29, non-invasive = 31) from the most-prevalent emm-types within the AFROStrep Biorepository collected during a prospective passive surveillance laboratory study conducted in 2016 in Cape Town. We used the Sensititre® STP6F system to perform antimicrobial susceptibility testing (AST) to determine the minimum inhibitory concentrations of a panel of 20 clinically relevant antibiotics. Breakpoints were assigned using the CLSI M100‐Ed31(2021) guidelines.

Results
Eight (13%) isolates (4 invasive and 4 non-invasive) were found to be resistant to Tetracycline, seven of which were emm76. The remaining isolate (invasive emm43) was also resistant to both Azithromycin and Erythromycin.  All isolates were susceptible at low MICs to Moxifloxacin, Penicillin, Levofloxacin, Meropenem, Azithromycin, Ertapenem, Cefuroxime, Amoxicillin/Clavulanic acid, Trimethoprim/Sulfamethoxazole, Ceftriaxone, Linezolid, Vancomycin, Cefotaxime, Clindamycin, Daptomycin, Cefepime, Chloramphenicol and Tigecycline.

Conclusion
In our setting, GAS remains susceptible to routine antimicrobial agents used in our low-resourced setting.  Knowledge of the prevalence of resistance and MIC trends of commonly used antibiotics for Streptococcus pyogenes will aid in avoiding therapeutic failures and inform future vaccine development.