Effect of fluoxetine on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei.

Aim: This study evaluated the effect of fluoxetine (FLU) on planktonic and biofilm growth and the antimicrobial susceptibility of Burkholderia pseudomallei. Materials & methods: The minimum inhibitory concentrations (MICs) for FLU were determined by broth microdilution. Its effect on growing and mature biofilms and its interaction with antibacterial drugs were evaluated by assessing biofilm metabolic activity, biomass and structure through confocal microscopy. Results: The FLU MIC range was 19.53-312.5 µg/ml. FLU eradicated growing and mature biofilms of B. pseudomallei at 19.53-312.5 µg/ml and 1250-2500 µg/ml, respectively, with no structural alterations and enhanced the antibiofilm activity of antimicrobial drugs. Conclusion: These results bring perspectives for the use of FLU in the treatment of melioidosis, requiring further studies to evaluate its applicability.

Antimicrobial susceptibility and production of virulence factors by bacteria recovered from bitches with pyometra.

Pyometra is one of the most common diseases in adult female dogs, characterized by a suppurative bacterial infection of the uterus with accumulation of inflammatory exudate and a variety of local and systemic clinical manifestations. This study aimed to identify the bacteria within the uterine content and vaginal canal of bitches with pyometra and evaluate their antimicrobial susceptibility and production of virulence factors. Uterine and vaginal content were collected with sterile swabs from 30 bitches diagnosed with pyometra. Bacteria were identified and assessed for their antimicrobial susceptibility and production of virulence factors, including biofilms, siderophores, proteases and hemolysins, both in planktonic and biofilm forms. A total of 82 bacterial isolates (35 uterus, 47 vagina), belonging to 21 species, were identified, with Escherichia coli as the most prevalent species (32/82, 39%). As for susceptibility, 39/79 (49.4%) isolates were resistant to one or more drugs, with resistance proportion among Gram-positive bacteria (87.5%) higher (p < .05) than that observed for Gram-negative bacteria (32.7%). Four coagulase-negative Staphylococcus species were resistant to methicillin. Regarding virulence, the isolates had low production of biofilms, siderophores, proteases and hemolysins, suggesting that the occurrence of pyometra might be more associated with host-related factors than bacterial virulence.

Rhamnolipid enhances Burkholderia pseudomallei biofilm susceptibility, disassembly and production of virulence factors.

Aim: This study evaluated the effect of the biosurfactant rhamnolipid on the antimicrobial susceptibility, biofilm growth dynamics and production of virulence factors by Burkholderia pseudomallei. Materials & methods: The effects of rhamnolipid on planktonic and biofilm growth and its interaction with antibacterial drugs were evaluated. Then, its effects on growing and mature biofilms and on protease and siderophore production were assessed. Results: Rhamnolipid did not inhibit B. pseudomallei growth, but significantly enhanced the activity of meropenem and amoxicillin-clavulanate against mature biofilms. Rhamnolipid significantly reduced the biomass of mature biofilms, significantly increased protease production by growing and mature biofilms and siderophore release by growing biofilms. Conclusion: Rhamnolipid enhances the antimicrobial activity against B. pseudomallei, assists biofilm disassembly and alters protease and siderophore production by bacterial biofilms.

Chlorpromazine-impregnated catheters as a potential strategy to control biofilm-associated urinary tract infections.

Aim: This study proposes the impregnation of Foley catheters with chlorpromazine (CPZ) to control biofilm formation by Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae. Materials & methods: The minimum inhibitory concentrations (MICs) for CPZ and the effect of CPZ on biofilm formation were assessed. Afterward, biofilm formation and the effect of ciprofloxacin and meropenem (at MIC) on mature biofilms grown on CPZ-impregnated catheters were evaluated. Results: CPZ MIC range was 39.06-625 mg/l. CPZ significantly reduced (p < 0.05) biofilm formation in vitro and on impregnated catheters. In addition, CPZ-impregnation potentiated the antibiofilm activity of ciprofloxacin and meropenem. Conclusion: These findings bring perspectives for the use of CPZ as an adjuvant for preventing and treating catheter-associated urinary tract infections.