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

Biagio Santella; Enrica Serretiello; Anna De Filippis; Folliero Veronica; Domenico Iervolino; Federica Dell'Annunziata; Roberta Manente; Francesco Valitutti; Emanuela Santoro; Pasquale Pagliano; Massimiliano Galdiero; Giovanni Boccia; Gianluigi Franci

doi:10.3390/antibiotics10070851

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

Antibiotics (Basel). 2021 Jul 13;10(7):851. doi: 10.3390/antibiotics10070851.

Authors

Affiliations

¹ Section of Microbiology and Virology, University Hospital "Luigi Vanvitelli", 80138 Naples, Italy.
² Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", 80138 Naples, Italy.
³ Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy.
⁴ Clinical Pediatrics and Pediatrics, University Hospital "San Giovanni di Dio e Ruggi d'Aragona", 84131 Salerno, Italy.
⁵ Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", University of Salerno, 84081 Baronissi, Italy.
⁶ Dai Dipartimento di Igiene Sanitaria e Medicina Valutativa U.O.C. Patologia Clinica E Microbiologica, Azienda Ospedaliero-Universitaria S. Giovanni di Dio e Ruggi D'Aragona Scuola Medica Salernitana, Largo Città di Ippocrate, 84131 Salerno, Italy.

Abstract

Lower respiratory tract infections (LRTIs) are the most common infections in humans. It is estimated that 2.74 million deaths worldwide occur each year due to LRTIs. The aim of the study was to determine the frequency and antibiotic susceptibility pattern of microorganisms isolated from respiratory samples of patients with LRTIs. Between January 2015 and December 2019, a total of 7038 sputum and bronchoaspirate samples from suspected LRTI patients were collected. Among them, 2753 samples (39.1%) showed significant microbial growth on culture media. The LRTI rate was higher in patients with male gender (67.1%) and with age between 40-59 years (48.6%). The microorganism identification and antibiotic susceptibility testing were performed with Vitek 2. Out of 4278 isolates species, 3102 (72.5%) were Gram-negative bacteria, 1048 (24.5%) were Gram-positive bacteria, and 128 (3.0%) were Candida spp. Major microorganisms isolated were Acinetobacter baumannii (18.6%), Staphylococcus aureus (15.2%), Pseudomonas aeruginosa (14.2%), and Klebsiella pneumoniae (10.9%). In antimicrobial susceptibility testing, Staphylococcus aureus isolates were mostly resistant to Penicillin G (84.1%) and Oxacillin (48.1%), whereas they demonstrated maximum sensitivity to Tigecycline (100%) and Linezolid (99.5%). Among Gram-negative isolates, Acinetobacter baumannii showed maximum sensitivity to Colistin but was resistant to other antibiotics (95-99%). Klebsiella pneumoniae isolates were mostly resistant to Cefotaxime (72.7%) and sensitive to Gentamicin (54.3%), and Pseudomonas aeruginosa was resistant to Ciprofloxacin (40.3%) and sensitive to Amikacin (85.9%). Gram-negative bacteria represented the species most commonly isolated. A high rate of antimicrobial resistance was observed in this study. In conclusion, the correct identification of causative microorganisms and their susceptibility patterns to antibiotics is crucial for choosing targeted and effective antibiotic therapy in LRTIs, and to prevent the emergence of multidrug-resistant bacteria.

Keywords: antimicrobial resistance; antimicrobial stewardship; epidemiology; lower respiratory tract infections; nosocomial infections.