Microbial Distribution and Antibiotic Susceptibility of Lower Respiratory Tract Infections Patients From Pediatric Ward, Adult Respiratory Ward, and Respiratory Intensive Care Unit

Abstract

Introduction: Lower respiratory tract infections (LRTIs) account for significant morbidity and mortality in patients admitted to hospitals worldwide, especially in children and elderly. The prevalent microorganisms and antibiotic susceptibility were investigated among LRTI patients from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU) in order to achieve more efficient treatment protocols and better recovery.

Methods: In this retrospective cross-sectional study (January 2016 to December 2019), 4,161 positive culture samples out of 18,798 different specimens (9,645 respiratory tract samples and 9,153 blood samples) from LRTI patients were analyzed for pathogen incidence and antibiotic sensitivity.

Results: Among the respiratory tract cultures, the frequency of Gram-negative bacterial strains was higher than Gram-positive bacterial strains. Pseudomonas aeruginosa was the dominant pathogen in both the adult respiratory ward (n = 156, 21.49%) and RICU (n = 975, 35.67%), whereas Staphylococcus aureus (n = 66, 19.19%) was the most common bacterium in the pediatric ward. Among the blood cultures, Gram-positive bacteria remained the major microorganisms involved in LRTIs, and the most frequent pathogen was Staphylococcus epidermidis (n = 59, 47.20%) in the pediatric ward and Staphylococcus aureus (n = 10, 21.8%) in adult respiratory ward. However, Gram-negative bacteria were the main pathogens in the RICU, of which Klebsiella pneumoniae (n = 51, 27.57%) is the most prevalent. Pseudomonas aeruginosa of LRTI patients remained highly susceptible (>70%) to routine antibiotics in pediatric ward. However, it only had high susceptibility to amikacin, tobramycin, gentamicin in both the adult respiratory ward and RICU and its antibiotic sensitivity to meropenem and imipenem was moderate in the adult respiratory ward and mild (<30%) in the RICU. Staphylococcus aureus isolated from LRTI patients was highly susceptible to linezolid, daptomycin, teicoplanin, vancomycin, tigecycline, rifampicin, and trimethoprim/sulfamethoxazole in all three wards, moderately susceptible to gentamicin in both the adult respiratory ward and RICU and to clindamycin, oxacillin, moxifloxacin only in the adult respiratory ward.

Conclusions: Microbial distribution and their patterns of antibiotic susceptibility revealed a high divergence among LRTI patients admitted to different wards in this hospital. Thus, different antibiotic therapies should be considered for distinct age groups.

Keywords: Klebsiella pneumoniae; Pseudomonas aeruginosa; Staphylococcus aureus; antibiotic susceptibility; lower respiratory tract infections.

FIGURE 1

Monthly distribution of sampling (A) respiratory tract cultures, (B) blood cultures in patients with lower respiratory tract infections from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU). More respiratory tract and blood cultures of LRTI patients from three wards were performed in all seasons (January to December) than in cold seasons (October to December). RICU, respiratory intensive care unit.

FIGURE 2

Distribution of microorganisms in positive respiratory tract cultures of lower respiratory tract infection patients from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU). Gram-negative bacteria remained the major pathogens among the respiratory tract cultures. P. aeruginosa, Pseudomonas aeruginosa; A. baumannii, Acinetobacter baumannii; K. pneumonia, Klebsiella pneumonia; S. maltophilia, Stenotrophomonas maltophilia; H. influenza, Haemophilus influenza; E. coli, Escherichia coli; M. catarrhalis, Moraxella catarrhalis; E. cloacae, Enterobacter cloacae; B. cepacia, Burkholderia cepacia; S. aureus, Staphylococcus aureus; S. pneumonia, Streptococcus pneumonia; C. albicans, Candida albicans; C. tropicalis, Candida tropicalis; C. glabrata, Candida glabrata.

FIGURE 3

Distribution of microorganisms in positive blood cultures of lower respiratory tract infection patients from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU). Among the blood cultures, the frequency of Gram-positive bacteria was higher than Gram-negative bacteria in the pediatric ward and adult respiratory ward, and Gram-negative bacterial strains remained the major pathogens in the RICU. K. pneumonia, Klebsiella pneumonia; E. coli, Escherichia coli; A. baumannii, Acinetobacter baumannii; S. epidermidis, Staphylococcus epidermidis; S. hominis, Staphylococcus hominis; S. aureus, Staphylococcus aureus; S. capltis, Staphylococcus capltis; S. haemolyticus, Staphylococcus haemolyticus; E. faecium, Enterococcus faecium; S. agalactiae, Streptococcus agalactiae; S. pneumonia, Streptococcus pneumoniae; C. albicans, Candida albicans; C. parapsilosis, Candida parapsilosis.

FIGURE 4

Major Gram-negative bacteria isolated and their drug-susceptibility rates in patients with lower respiratory tract infections from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU). The antimicrobial susceptibility performed by VITEK 2 Compact or the manual Kirby–Bauer (K–B) disk diffusion method. RICU, respiratory intensive care unit.

FIGURE 5

Major Gram-positive bacteria isolated and their drug-susceptibility rates in patients with lower respiratory tract infections from the pediatric ward, adult respiratory ward, and respiratory intensive care unit (RICU). The antimicrobial susceptibility performed by VITEK 2 Compact or the manual Kirby–Bauer (K–B) disk diffusion method. RICU, respiratory intensive care unit.