Comparative analysis between levofloxacin and ciprofloxacin to assess their bactericidal activity using antimicrobial susceptibility disk diffusion on isolates obtained from urine samples

Abstract EN

Background : Urinary tract infection is one of the most common clinical presentations at the Bahrain Defence Force Hospital (BDFH) where fluoroquinolone (ciprofloxacin) is the first-line prescribed antibiotic.

Levofloxacin has recently been added to the antibiotic formulary.

This study was based on culture-positive urine specimens collected in the period February 1 to August 31, 2011.

The objective of this study was to analyze the antimicrobial sensitivity of ciprofloxacin compared to levofloxacin on clinical isolates obtained from patients with UTI at BDFH.

Methods : The sensitivity analysis on both antibiotics was carried out using 5-microgram disk diffusion on 452 isolates obtained from patients.

The in-vitro activity of the two fluoro-quinolones was evaluated based on the zone of inhibition produced by each antibiotic.

The values for the zones were obtained from the Clinical and Laboratory Standards Institute (CLSI-2011).

Results : Overall levofloxacin provided an improved sensitivity response in patients with culture-positive Enterobacteriacae (71 %) as compared to ciprofloxacin (67 %).

In addition, the culture results showed that the most common UTI causative organisms in BDFH were E-coli (63.9 %), followed by Klebsiella pneumoniae (17.3 %), Proteus species (7.1 %) and Pseudomonas aeruginosa (2.7 %).

There was a statistically significant difference (p = .004) in response to the two fluoroquinolones among the four groups of organisms.

Levofloxacin showed statistically significant disk diffusion susceptibility response among E-coli (M = 20.38, 95 % CI [18.69, 22.07]) and Klebsiella pneumoniae (M = 26.33, 95 % CI [24.45, 28.22]) p = .001, while there was no significant difference in disk diffusion susceptibility response among Proteus species and Pseudomonas aeruginosa.

Conclusion : Levofloxacin had a significantly better disk diffusion sensitivity response than ciprofloxacin in patients with E-coli and Klebsiella pneumoniae culture positive urine specimens.