Abstract
Background
Thoracic and respiratory infections require timely microbiological diagnosis, whereas pathogen distribution and antimicrobial susceptibility may vary substantially across settings and specimen types. Local laboratory‐based data can therefore support antimicrobial‐resistance surveillance and interpretation of culture results.
Methods
We conducted a retrospective laboratory‐based study of thoracic and respiratory culture records processed at a private referral microbiology laboratory in Damascus, Syria, from January 1, 2022, to December 31, 2025. Culture‐positive specimens were categorized as pleural‐space, deep pulmonary/lung surgical, or tracheal/airway specimens. Pleural‐space and deep pulmonary/lung surgical specimens were combined as the primary analysis group, whereas airway specimens were analyzed separately as an exploratory subgroup. Antimicrobial susceptibility testing was interpreted according to CLSI M100, 30th edition (2020), with agent‐specific tested denominators and cautious interpretation of estimates based on fewer than 30 isolates.
Results
Among 356 eligible culture records, 136 were positive (38.2%). The mean age was 42.3 ± 21.5 years, and 66.9% were from male patients. Bacterial isolates accounted for 127/136 (93.4%). The most frequent bacteria were
Staphylococcus aureus
(38/127, 29.9%),
Escherichia coli
(30/127, 23.6%),
Klebsiella pneumoniae
(26/127, 20.5%), and
Pseudomonas aeruginosa
(18/127, 14.2%). In the primary pleural/deep group,
S
.
aureus
showed high in vitro susceptibility to vancomycin (35/35, 100%) and linezolid (33/35, 94.3%). Among dominant gram‐negative isolates, amikacin and meropenem showed comparatively high activity, whereas several cephalosporins, fluoroquinolones, and trimethoprim‐sulfamethoxazole showed lower susceptibility. No colistin‐resistant isolate was identified.
Conclusion
Culture‐positive thoracic and respiratory specimens in this Syrian referral laboratory showed a mixed
S
.
aureus
and gram‐negative microbiological profile. These findings provide local laboratory‐based susceptibility signals that support organism‐specific AST interpretation and antimicrobial‐resistance surveillance, whereas small organism‐specific denominators preclude their use as formal empirical‐treatment recommendations.