Trimethoprim-sulfamethoxazole prophylaxis and antibiotic nonsusceptibility in invasive pneumococcal disease

Area of Science:

• * Infectious Diseases
• * Microbiology
• * Public Health

Background:

• * Invasive pneumococcal disease (IPD) remains a significant public health concern globally.
• * Antimicrobial resistance (AMR) poses a growing threat to effective treatment of bacterial infections.
• * Understanding the impact of prophylactic antibiotic use on AMR is crucial for guiding clinical practice.

Purpose of the Study:

• * To investigate the association between trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis and antimicrobial resistance patterns in *Streptococcus pneumoniae*.
• * To determine if TMP-SMX use influences resistance to other commonly used antibiotics.
• * To provide evidence for empirical treatment strategies in patients with a history of TMP-SMX use.

Main Methods:

• * Analysis of 5,043 invasive pneumococcal disease (IPD) isolates collected through South African national surveillance.
• * Retrospective estimation of the effect of TMP-SMX prophylaxis on antimicrobial susceptibility testing (AST) results.
• * Statistical assessment of the correlation between TMP-SMX non-susceptibility and resistance to other antimicrobial agents.

Main Results:

• * Patients on TMP-SMX prophylaxis were significantly more likely to harbor pneumococcal isolates non-susceptible to TMP-SMX.
• * TMP-SMX non-susceptibility was associated with increased resistance to penicillin, erythromycin, and rifampin.
• * A strong correlation was observed between TMP-SMX non-susceptibility and multidrug resistance (MDR) in IPD isolates.

Conclusions:

• * Prophylactic use of TMP-SMX is associated with the emergence of antimicrobial resistance in *Streptococcus pneumoniae*.
• * Resistance to TMP-SMX predicts resistance to other critical antibiotics, complicating treatment options.
• * Clinical guidelines should consider patient history of TMP-SMX use when initiating empirical therapy for suspected IPD.