Key Roles of Human Polymorphonuclear Cells and Ciprofloxacin in Lactobacillus Species Infection Control

Abstract

Lactobacilli have the potential to act as reservoirs of antibiotic resistance genes similar to those found in human pathogens, with the risk of transferring these genes to many pathogenic bacteria. In this study, we investigated the role of human polymorphonuclear cells (PMNs) against Lactobacillus spp. both resistant and susceptible to ciprofloxacin (a fluoroquinolone) and the effect of ciprofloxacin on the interaction between PMNs and three Lactobacillus spp. with different patterns of susceptibility to this drug. Hence, the primary functions of PMNs, such as phagocytosis and bacterial intracellular killing, against lactobacilli were investigated. The rate of PMN phagocytosis was high for ciprofloxacin-sensitive and ciprofloxacin-resistant strains. The patterns of intracellular killing of ciprofloxacin-sensitive and ciprofloxacin-resistant strains by PMNs underline that PMNs alone were able to kill lactobacilli. The addition of ciprofloxacin to PMNs did not result in a significant increase in the bacterial uptake by phagocytes. On the contrary, ciprofloxacin had a marked effect on PMN intracellular killing, resulting in increased numbers of killed ciprofloxacin-sensitive bacteria in comparison with antibiotic-free controls. Our data show that by itself, the profile of antibiotic resistance does not constitute an intrinsic factor of greater or lesser pathogenicity toward the host. The ability of PMNs to kill a diverse array of bacterial pathogens is essential for human innate host defense, primarily in immunocompromised patients. Lactobacillus spp., considered nonpathogenic bacteria of the human gastrointestinal and vaginal microbiotas, are widely used as probiotics in dairy products. Moreover, they can positively interact with other microorganisms of the human microbiota (1).Infections caused by lactobacilli are extremely rare; however, they can spread into the blood and cause serious clinical infections (2, 3). Many investigators have demonstrated that lactobacilli have a high natural resistance to many antimicrobial drugs, such as fluoroquinolones, e.g., ciprofloxacin (CIP) (4-7); our recent studies showed that the mechanism of resistance to fluoroquinolones could be associated with the presence of a NorA-like efflux pump found in ciprofloxacin-resistant (CIP r ) strains of L. fermentum isolated from the human oral cavity (8).For several decades, studies on selection and dissemination of antibiotic resistance have focused mainly on clinically relevant species. The magnitude of the problem is significantly increased by the ability of bacteria to transfer resistance horizontally and by the mounting increase in the overuse and misuse of antibiotics, which has created an enormous selective pressure toward resistant bacteria.Gene transfer occurs widely in vivo between pathogenic and commensal bacteria of the human microbiota, as identical resistance genes are present in several bacterial species from different hosts. Lactobacilli have the potential to act as reservoirs of antibiotic resistance genes similar to th...

Broad‐spectrum antimicrobial activity of cinnamoyl esterase‐producing Lactobacilli and their application in fermented rice bran

“…According to Georgieva et al ., 15 resistances to the glycopeptide family of antibiotics, such as vancomycin, is an essential characteristic of the genera Leuconostoc , Pediococcus , and Lactobacillus . Intrinsic resistance to ciprofloxacin is common among the genera, and streptomycin resistance is frequently observed in Lactobacilli 32,33 …”

Techno-functional characterization of indigenous Lactobacillus isolates from the traditional fermented foods of Meghalaya, India

“…Few lactobacilli seem to be intrinsically resistant ( Mandras et al., 2016 ) to second-generation quinolones-fluoroquinolones, viz. norfloxacin, ciprofloxacin, levofloxacin by a presently unknown resistance mechanism ( Hummel et al., 2007 ).…”

Enhanced Killing of Candida krusei by Polymorphonuclear Leucocytes in the Presence of Subinhibitory Concentrations of Melaleuca alternifolia and “Mentha of Pancalieri” Essential Oils

“…PMNs were separated from lithium heparinized venous human blood using Ficoll–Paque (Pharmacia S.p.A., Milan, Italy), and adjusted to 10 6 cells/mL in RPMI 1640 medium (Sigma-Aldrich) as previously described in detail [5,42]. PMN viability, determined by trypan blue exclusion, was greater than 95% [43].…”