sitafloxacin and Bacteremia

Sitafloxacin is a newly approved oral fluoroquinolone in Thailand for treatment of respiratory tract and\ urinary tract infections. Initial in vitro susceptibility testing showed its effect on Escherichia coli with extended-spectrum betalactamases (ESBL), Klebsiella pneumoniae with ESBL, Pseudomonas aeruginosa, and carbapenem resistant Acinetobacter baumannii. To retrospectively review in vitro susceptibility to sitafloxacin on clinical isolates from HRH Princess Maha Chakri\ Sirindhorn Medical Center, Srinakharinwirot University (SWU) and Samitivej Sukhumvit Hospital (SVH).. Between January 2014 and June 2015, all clinical isolates from SWU and SVH that were added to test\ in vitro susceptibility to sitafloxacin were included in the present study. The susceptibility for sitafloxacin was identified by disk diffusion method with inhibition zone diameter 19 mm or greater, considered to be sensitive, and smaller than 16 mm considered to be resistance. The comparative activities of sitafloxacin to other antibiotics were determined by organisms. All bacteria with count numbers of more than 30 would be shown in results.. Among 1,288 clinical isolates from 1,163 clinical specimens that were added in vitro susceptibility test to sitafloxacin, there were 728 clinical isolates from SWU and 560 clinical isolates from SVH. The most common specimens were sputum (482), urine (385), pus (96), and blood (81). Organisms with comparative activities included E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, and Stenotrophomonas maltophilia. The susceptible percentage of sitafloxacin was 72.69% for all E. coli (n = 216) (68.26% for E. coli with ESBL and 86.96% for E. coli without ESBL), 39.31% for all K. pneumoniae (n = 173) (50% for K. pneumoniae with ESBL, 61.11% for K. pneumoniae without ESBL and 13.11% for carbapenem resistant enterobacteriaceae (CRE) strain of K. pneumoniae), 60.66% for P. aeruginosa (n = 366), 66.32% for A. baumannii (n = 386) and 93.94% for S. maltophilia (n = 33). Sitafloxacin had more susceptible percentage as compared to ciprofloxacin for all strains of E. coli, K. pneumoniae, P. aeruginosa, and A. baumannii and more susceptible percentage as compared to levofloxacin for S. maltophilia. Although sitafloxacin might not have good activity against CRE strain of K. pneumoniae, at least some (13.11%) were susceptible as compared to 0% for ciprofloxacin.. Sitafloxacin had more susceptible percentage to E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, and S. maltophilia compared to comparative fluoroquinolones. It should be considered an antibiotic for treatment of respiratory tract and urinary tract infections caused by the resistant strains of these bacteria with susceptible proven of in vitro susceptibility.

Topics: Academic Medical Centers; Acinetobacter baumannii; Anti-Bacterial Agents; Bacteremia; Ciprofloxacin; Escherichia coli; Fluoroquinolones; Gram-Negative Bacteria; Humans; In Vitro Techniques; Klebsiella pneumoniae; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Respiratory Tract Infections; Stenotrophomonas maltophilia; Thailand; Urinary Tract Infections

The emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) complex has posed a great challenge to clinicians worldwide. Sitafloxacin has been shown to have in vitro activity against pathogens resistant to other fluoroquinolones. However, data comparing the anti-CRAB activity of sitafloxacin with that of other antimicrobial agents are limited.. Genospecies were identified by 16S-23S ribosomal RNA intergenic spacer sequencing. Minimum inhibitory concentrations (MICs) were determined by an agar dilution method. Isolates with sitafloxacin MICs ≤ 2 mg/L were provisionally considered as susceptible to sitafloxacin. The MIC breakpoint for tigecycline susceptibility was 2 mg/L.. A total of 167 CRAB complex blood isolates (146 A. baumannii, 7 Acinetobacter pittii, and 14 Acinetobacter nosocomialis) were collected from January 2009 to December 2011. Around 90% of the A. baumannii isolates were resistant to amikacin, cefepime, ceftazidime, piperacillin/tazobactam, ampicillin/sulbactam, ciprofloxacin, and levofloxacin. By contrast, the rate of resistance to colistin, sitafloxacin, and tigecycline was relatively low (0%, 41.1%, and 65.1%, respectively). The MIC50 and MIC90 of ciprofloxacin, levofloxacin, and sitafloxacin were 128 mg/L and >128 mg/L; 16 mg/L and 64 mg/L; 2 mg/L and 8 mg/L, respectively. Compared with ciprofloxacin and levofloxacin, sitafloxacin had a significantly lower MIC (p < 0.001), and the rate of resistance to sitafloxacin was significantly lower than that to ciprofloxacin (97.9% vs. 41.1%, p < 0.001), levofloxacin (97.3% vs. 41.1%, p < 0.001), and tigecycline (p < 0.001).. Sitafloxacin has acceptable in vitro activity against CRAB, even against isolates resistant to other fluoroquinolones. Sitafloxacin may be considered an alternative drug of choice in treating CRAB related infections.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Anti-Bacterial Agents; Bacteremia; beta-Lactam Resistance; Carbapenems; DNA, Bacterial; DNA, Intergenic; DNA, Ribosomal; Fluoroquinolones; Humans; Microbial Sensitivity Tests; RNA, Ribosomal, 16S; RNA, Ribosomal, 23S; Sequence Analysis, DNA