In Vitro Antibiofilm Efficacies of Different Antibiotic Combinations with Zinc Sulfate against Pseudomonas aeruginosa Recovered from Hospitalized Patients with Urinary Tract Infection.

Walid Elkhatib,Ayman Noreddin

doi:10.3390/antibiotics3010064

Abstract

Urinary tract infections (UTIs) are a serious healthcare dilemma influencing millions of patients every year and represent the second most frequent type of body infection. Pseudomonas aeruginosa is a multidrug-resistant pathogen causing numerous chronic biofilm-associated infections including urinary tract, nosocomial, and medical devices-related infections. In the present study, the biofilm of P. aeruginosa CCIN34519, recovered from inpatients with UTIs, was established on polystyrene substratum and scanning electron microscopy (SEM) and was utilized for visualization of the biofilm. A previously described in vitro system for real-time monitoring of biofilm growth/inhibition was utilized to assess the antimicrobial effects of ciprofloxacin, levofloxacin, moxifloxacin, norfloxacin, ertapenem, ceftriaxone, gentamicin, and tobramycin as single antibiotics as well as in combinations with zinc sulfate (2.5 mM) against P. aeruginosa CCIN34519 biofilm. Meanwhile, minimum inhibitory concentrations (MICs) at 24 h and mutant prevention concentrations (MPCs) at 96 h were determined for the aforementioned antibiotics. The real-time monitoring data revealed diverse responses of P. aeruginosa CCIN34519 biofilm to the tested antibiotic-zinc sulfate combinations with potential synergisms in cases of fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin, and norfloxacin) and carbapenem (ertapenem) as demonstrated by reduced MIC and MPC values. Conversely, considerable antagonisms were observed with cephalosporin (ceftriaxone) and aminoglycosides (gentamicin, and tobramycin) as shown by substantially increased MICs and MPCs values. Further deliberate in vivo investigations for the promising synergisms are required to evaluate their therapeutic potentials for treatment of UTIs caused by P. aeruginosa biofilms as well as for developing preventive strategies.

Highlights

Biofilm associated infections tend to be reluctant and difficult to eradicate [1]
Variable pressure scanning electron microscopy was used for visualization of the biofilm on polystyrene plates after 12 h of incubation in absence of physical distortion or gold coating of the biofilm
Real-time monitoring data showed that ciprofloxacin alone inhibited the biofilm growth for 4, 8, 20, and 38 h with the tested concentration levels of 0.1, 0.2, 0.4, and 0.8 μg/mL, respectively

Summary

Introduction

Biofilm associated infections tend to be reluctant and difficult to eradicate [1]. The increased antibiotic resistance of biofilms was generally attributed to the biofilm-associated patterns of gene expression, slow growth rate, and substantially diminished antimicrobial diffusion within the biofilm [2].Biofilms are considered relevant to the clinical settings because they play key roles in the ability of biofilm-ensconced bacteria to tolerate relatively high therapeutic doses of antibiotics and persist in chronic infections [3,4]. Biofilm associated infections tend to be reluctant and difficult to eradicate [1]. The increased antibiotic resistance of biofilms was generally attributed to the biofilm-associated patterns of gene expression, slow growth rate, and substantially diminished antimicrobial diffusion within the biofilm [2]. Biofilms are considered relevant to the clinical settings because they play key roles in the ability of biofilm-ensconced bacteria to tolerate relatively high therapeutic doses of antibiotics and persist in chronic infections [3,4]. States annually [6,7]. UTIs are the most common urological disease in the United States, with a financial burden on the healthcare system exceeding $3.5 billion annually [8]

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