Background:Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation.Objectives:In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated.Materials and Methods:Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant.Results:The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella.Conclusions:Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation.

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Oily skin areas of small animals may be a source of novel biosurfactant-producing bacteria. lularly and contain hydrophobic and hydrophilic moieties that confer the ability to accumulate between fluid phases, thus reducing surface and interfacial tension at the surface and interface respectively (2). Rosenberg and Ron (3) suggested that biosurfactants can be divided into low-molecular-mass molecules, which efficiently lower surface and interfacial tension, and high molecular-mass polymers, which are more effective as emulsion-stabilizing agents. Recently, several groups have presented intriguing data suggesting that biosurfactants are important for microbial growth and survival in the environment. For example, surfactin production is necessary for fruiting body formation by Bacillus subtilis (4). Apart from their obvious role as agents that decrease Background: Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. They are a structurally diverse group of surface-active molecules and are highly sought after biomolecules for both present and future applications. Objectives: The aim of the present study was to isolate and identify biosurfactant producing bacteria from the ear canal and inguinal areas (oily skin areas) of dogs and cats. Materials and Methods: Eighty inguinal area and ear canal samples were collected from stray and owned dogs and cats (10 animals each, 20 samples) and screened for biosurfactant-producing bacteria using criteria such as hemolysis, oil spreading and E 24 emulsification index tests. The isolated strains were identified at genus level. Results: 42 hemolytic bacterial strains (20 from dogs and 22 from cats) were isolated. The owned animal's samples had a higher population of positive strains than the stray ones. In total 11 isolates (26. 2%) were positive for all examinations, out of these 9 (21. 1%) isolates belonged to owned animals. 9 isolates (out of 11) (82%) were gram positive of which 4 (44. 4%) were Bacillus spp. and 3 (27. 2%) Lactobacillus spp. Conclusions: The results showed that biosurfactant producing bacteria are distributed in the oily skin areas of both dogs and cats. Further investigation into the composition of the biosurfactants and phylogenetic determination of biosurfactant producing bacteria is suggested.

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