Lower Respiratory Tract Pathogens and Their Antimicrobial Susceptibility Pattern: A 5-Year Study

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Lower respiratory tract infections (LRTIs) are a leading cause of mortality worldwide, necessitating an understanding of causative pathogens and their resistance patterns.
• Effective management of LRTIs relies on accurate identification of microbial agents and their susceptibility to antibiotics to guide appropriate treatment strategies.

Purpose of the Study:

• To determine the frequency of microorganisms isolated from respiratory samples of patients diagnosed with LRTIs.
• To analyze the antibiotic susceptibility patterns of these isolated microorganisms.
• To provide data that can inform targeted antibiotic therapy and combat antimicrobial resistance in LRTI management.

Main Methods:

• Collection and culture of 7038 sputum and bronchoaspirate samples from suspected LRTI patients between January 2015 and December 2019.
• Identification of microbial isolates and antibiotic susceptibility testing performed using the Vitek 2 system.
• Statistical analysis of microbial prevalence and resistance rates.

Main Results:

• Significant microbial growth was observed in 39.1% of samples, with Gram-negative bacteria (72.5%) being the predominant isolates, followed by Gram-positive bacteria (24.5%) and Candida spp. (3.0%).
• Key identified pathogens included Acinetobacter baumannii (18.6%), Staphylococcus aureus (15.2%), Pseudomonas aeruginosa (14.2%), and Klebsiella pneumoniae (10.9%).
• High rates of antimicrobial resistance were noted, with specific resistances observed in Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa against commonly used antibiotics, while sensitivity varied for specific agents like Tigecycline, Linezolid, Colistin, Gentamicin, and Amikacin.

Conclusions:

• Gram-negative bacteria are the most frequently isolated microorganisms in LRTIs, exhibiting significant antimicrobial resistance.
• The study underscores a high prevalence of multidrug-resistant bacteria, posing a challenge for effective LRTI treatment.
• Accurate identification of pathogens and their antibiotic susceptibility profiles is critical for selecting effective therapies and preventing the spread of resistance.