EC Microbiology

Background: Azithromycin is an amoxicillin antibiotic that has been widely used in the treatment of respiratory tract infections due to its broad-spectrum activity, favorable pharmacokinetics, and immunomodulatory properties.

Objective: To evaluate the in vitro sensitivity of common respiratory tract pathogens to azithromycin.

Methodology: This is a prospective cross-sectional study conducted in Shendi City, Sudan, from January to February 2025, at the Microbiology Laboratory, Faculty of Medical Laboratory Sciences at Shendi University. A total of 30 sputum samples were collected, from which fourteen strains of pathogenic gram-positive bacteria and two strains of pathogenic gram-negative bacteria were isolated and identified using Gram stain and biochemical tests.

Results: Of the 30 clinical specimens, Staphylococcus aureus was confirmed in 6 (60%), Streptococcus pyogenes in 2 (20%), Klebsiella pneumoniae in 1 (10%), and Pseudomonas aeruginosa in 1 (10%). Azithromycin demonstrated remarkable antimicrobial activity against all gram-positive bacteria and one of the gram-negative bacteria (Pseudomonas aeruginosa), which showed intermediate sensitivity.

Conclusion: The findings of this study indicate that Azithromycin can be used as an antibacterial agent against gram-positive bacterial strains.

 Keywords: Antimicrobial; Azithromycin; Gram-Positive Bacteria; Respiratory Tract Infection

1. Bartlett JG., et al. “Respiratory tract infections: pathogenesis, diagnosis, and management”. Journal of Clinical Microbiology 3 (2018): e01233-17.
2. Dudley MN., et al. “Pharmacokinetics and clinical utility of Azithromycin in respiratory tract infections”. Clinical Infectious Diseases 5 (2021): 815-824.
3. Gao Y., et al. “Antimicrobial resistance trends in respiratory tract pathogens: a global perspective”. Antimicrobial Agents and Chemotherapy 1 (2022): e01521-21.
4. Ventola CL. “The antibiotic resistance crisis: part 1: causes and threats”. P & T4 (2015): 277-283.
5. World Health Organization. “Global action plan on antimicrobial resistance”. Geneva: WHO (2020).
6. Seppala H., et al. “The effect of changes in the consumption of macrolide antibiotics on erythromycin resistance in group A streptococci in Finland”. New England Journal of Medicine 7 (1997): 441-446.
7. Hopkins S. “Clinical toleration and safety of azithromycin”. American Journal of Medicine3A (1991): 40S-45S.
8. Seppala H., et al. “Resistance to erythromycin in group A streptococci”. New England Journal of Medicine 5 (1992): 292-297.
9. Betriu C., et al. “Comparative in vitro activities of linezolid, quinupristin dalfopristin, moxifloxacin, and trovafloxacin against erythromycin susceptible and resistant streptococci”. Antimicrobial Agents and Chemotherapy 7 (2000): 1838-1841.
10. Jacobs MR., et al. “Susceptibility of 1100 Streptococcus pneumoniae strains isolated in 1997 from seven Latin American and Caribbean countries”. International Journal of Antimicrobial Agents 1 (2000): 1724.
11. Koneman EW., et al. “Color atlas and textbook of diagnostic microbiology”. 6^th Philadelphia: Lippincott Williams & Wilkins (2006).
12. MacFaddin JF. “Biochemical tests for identification of medical bacteria”. 3^rd Philadelphia: Lippincott Williams & Wilkins (2000).
13. Koneman EW., et al. “Color atlas and textbook of diagnostic microbiology”. 6^th Philadelphia: Lippincott Williams & Wilkins (2006).
14. Murray PR and Zeitinger JR. “Evaluation of Mueller-Hinton agar for disk diffusion susceptibility tests”. Journal of Clinical Microbiology 5 (1983): 1269-1271.
15. Cheesbrough M. “District laboratory practice in tropical countries”. Second edition. Part 2 (2006).
16. Mahboob N., et al. “Disk diffusion method in enriched Mueller Hinton agar for determining susceptibility of Candida isolates”. Journal of Dhaka Medical College 1 (2020): 28-33.
17. Ibrahim TA., et al. “Antibacterial activity of herbal extracts against multidrug resistant of bacteria from clinical origin”. Life Sciences Leaflets 15 (2011): 490-498.
18. Javed H., et al. “Antibiotic susceptibility patterns of respiratory pathogens”. Journal of Infection in Developing Countries 5 (2018): 345-350.
19. Abdelgader LM., et al. “Antimicrobial activity of azithromycin and erythromycin against Streptococcus pyogenes isolated from sore throat patients in Shendi, Sudan”. SAR Journal of Pathology and Microbiology 1 (2024): 1-7.