Comparative antimicrobial susceptibility of biofilm versus planktonic forms of Salmonella enterica strains isolated from children with gastroenteritis

• Published in: European journal of clinical microbiology & infectious diseases 2010-11, Vol.29 (11), p.1401-1405
• Main Authors: Papavasileiou, K, Papavasileiou, E, Tseleni-Kotsovili, A, Bersimis, S, Nicolaou, C, Ioannidis, A, Chatzipanagiotou, S
• Format: Article
• Language: English
• Subjects: Adolescent; Anti-Bacterial Agents - pharmacology; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antimicrobial agents; Bacteria; Bacterial diseases; Bacterial diseases of the digestive system and abdomen; Biofilms; Biofilms - drug effects; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Child; Child, Preschool; Drug Resistance, Bacterial; Gastroenteritis; Gastroenteritis - microbiology; Human bacterial diseases; Humans; Infant; Infectious diseases; Internal Medicine; Medical Microbiology; Medical sciences; Microbial Sensitivity Tests; Pharmacology. Drug treatments; Plankton - drug effects; Regrowth; Salmonella; Salmonella enterica; Salmonella enterica - drug effects; Salmonella enterica - isolation & purification; Salmonella enteritidis - drug effects; Salmonella enteritidis - isolation & purification; Salmonella Infections - microbiology; Salmonella typhimurium - drug effects; Salmonella typhimurium - isolation & purification
• ISSN: 0934-9723; 1435-4373
• DOI: 10.1007/s10096-010-1015-y

In the present study, 194 Salmonella enterica strains, isolated from infected children and belonging to various serotypes, were investigated for their ability to form biofilms and the biofilm forms of the isolated strains were compared to their corresponding planktonic forms with respect to the antimicrobial susceptibility. For the biofilm-forming strains, the minimum inhibitory concentration for bacterial regrowth (MICBR) from the biofilm of nine clinically applicable antimicrobial agents was determined, and the results were compared to the respective MIC values of the planktonic forms. One hundred and nine S. enterica strains out of 194 (56%) belonging to 13 serotypes were biofilm-forming. The biofilm forms showed increased antimicrobial resistance compared to the planktonic bacteria. The highest resistance rates of the biofilm bacteria were observed with respect to gentamicin (89.9%) and ampicillin (84.4%), and the lowest rates with respect to ciprofloxacin and moxifloxacin (2.8% for both). A remarkable shift of the MICBR₅₀ and MICBR₉₀ toward resistance was observed in the biofilm forms as compared to the respective planktonic forms. The development of new consensus methods for the determination of the antimicrobial susceptibility of biofilm forms seems to be a major research challenge. Further studies are required in order to elucidate the biofilm antimicrobial resistance mechanisms of the bacterial biofilms and their contribution to therapeutic failure in infections with in vitro susceptible bacteria.