<p>In-vitro Investigation of Antibiotics Efficacy Against Uropathogenic <em>Escherichia coli</em> Biofilms and Antibiotic Induced Biofilm Formation at Sub-Minimum Inhibitory Concentration of Ciprofloxacin</p>

Abstract

Background: Community-acquired urinary tract infections are associated with significant morbidity, and uropathogenic Escherichia coli (UPEC) alone causes 90% of urinary tract infections. This bacterium retains a diverse armament of virulence factors including fimbria, hemolysins, and siderophores production. In a post invasion scenario, formation of intracellular communities mimic biofilm-like characteristics and are linked to recurrent urinary tract infections. We investigated the effects of different frontline antibiotics on the formation, inhibition, and eradication of biofilms of virulent UPEC strains. Materials and Methods: A total of 155 UPEC strains were scrutinized for various virulence factors including gelatinase, cell surface hydrophobicity, hemagglutination, and serum bactericidal activity. Biofilm formation was confirmed by three different methods: Congo red agar, test tube, and tissue culture plate method. Biofilm inhibition and eradication assays were performed according to the standard protocols. Topographical analysis of biofilms was done by scanning electronic microscopy (SEM). Results: Out of 155 strains, 113 (73%) were strong biofilm formesr, while 37 (24%) produced biofilms at moderate level. Significant differences were observed between MICs of planktonic cells (MIC-p) and MICs of UPEC biofilms (MIC-b). Among tested frontline antibiotics, levofloxacin successfully inhibited biofilms at a concentration of 32 µg/mL, while trimethoprim eradicated biofilms at higher concentrations (512-1024 µg/mL). Ciprofloxacin treatment at sub-MIC level significantly enhanced biofilm formation (P<0.05). Conclusion: The majority of UPEC strains are strong biofilm formers and show higher tolerance towards frontline antibiotics in biofilm form. We observed significant inhibitory effects of levofloxacin (32 µg/mL) on UPEC biofilms, while treatment with sub-minimal concentrations of ciprofloxacin significantly enhanced biofilm formation. Out of all tested antibiotics, trimethoprim (512-1024 µg/mL) eradicated UPEC biofilms.

Synergistic effects of carvacrol, α-terpinene, γ-terpinene, ρ-cymene and linalool against Gardnerella species

“…This last combination was more effective in reducing the total biomass of the biofilm (~ 50%) than the whole EO (~ 30%). This further demonstrates that biofilm cultures susceptibility to antimicrobials cannot be predicted from the standardized MIC determinations 74 , 75 . Despite not being able to completely eradicate the biofilm biomass, cell culturability was significantly affected, with no colony detected in many of the tested conditions.…”

Effect of ciprofloxacin and in vitro gut conditions on biofilm of Escherichia coli isolated from clinical and environmental sources

“…The effects of antibiotic on preformed biofilm varied between different in vitro gut conditions. Sub‐MIC of ciprofloxacin has previously been shown to reduce biofilm formation (Dong et al, 2019) while another study showed contrary to the above in that it induced biofilm formation (Rafaque et al, 2020). However, during infection, pathogens are exposed to varied conditions in the gut; therefore, the effect of antibiotics under different in vitro gut conditions need better understanding.…”

“…Pereira et al (2007) found only one isolate harbouring qnr among 144 ciprofloxacin-resistant isolates (Pereira et al, 2007). This could be due to other resistance mechanisms such as QRDR mutations or overexpression of efflux pumps in fluoroquinolone-resistant strains (Jazeela et al, 2019;Rezazadeh et al, 2016;Shetty et al, 2019).…”

Sub-Inhibitory Concentrations of Amoxicillin and Tylosin Affect the Biofilm Formation and Virulence of Streptococcus suis

“…Hathroubi et al also observed that the sub-MIC penicillin G in Actinobacillus pleuropneumoniae ( A. pleuropneumoniae ) significantly affected biofilms, increased biomass and biofilm thickness, and induced phenotypic changes in biofilm structure [ 31 ]. Similarly, the study by Rafaque et al showed that, in the presence of sub-inhibitory concentrations of ciprofloxacin, the biofilm formation ability of Escherichia coli ( E. coli ) was significantly increased [ 32 ]. Moreover, Mlynek et al found that sub-inhibitory concentrations of Amoxicillin can induce the production of extracellular genes in Staphylococcus aureus ( S. aureus ), thereby stimulating the formation of biofilms [ 33 ].…”