Bactrim, a combination of sulfamethoxazole and trimethoprim, effectively targets a range of bacterial infections. Its activity spans both Gram-positive and Gram-negative bacteria, as well as certain other microorganisms.
Gram-positive bacteria susceptible to Bactrim include Staphylococcus aureus (methicillin-sensitive strains), Streptococcus pneumoniae (some strains), and Enterococcus faecalis (some strains). However, resistance is increasing, particularly among S. aureus (MRSA) and Enterococcus species. Always check local resistance patterns.
Gram-negative bacteria sensitive to Bactrim include Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, and Proteus mirabilis. Again, resistance varies geographically and should be considered before prescribing.
Beyond Gram-positive and Gram-negative bacteria, Bactrim also exhibits activity against certain atypical organisms such as Pneumocystis jirovecii (causative agent of Pneumocystis pneumonia) and Chlamydia trachomatis.
| Gram-positive | S. aureus (methicillin-sensitive), S. pneumoniae (some strains), E. faecalis (some strains) | MRSA resistance is common; resistance among other species is rising. |
| Gram-negative | E. coli, K. pneumoniae, H. influenzae, P. mirabilis | Resistance is increasing in many areas. Local antibiograms are invaluable. |
| Other | P. jirovecii, C. trachomatis | Generally good activity, though resistance monitoring is important. |
Remember to always consult current guidelines and local antibiograms to guide antibiotic selection. Empirical therapy should be adjusted based on culture and sensitivity results.
