Al- Anbar Medical Journal

Abstract

Background: L-phase variants or cell wall deficient bacteria are strains of bacteria that lack cell wall temporally. They are pleomorphic, a term that refers to change in size and shape. Recently, unusual antibiotic result was observed in such bacteria.
Objective: To investigate the role of vancomycin and some ion chelators like calcium and magnesium on the induction of gram-positive cocci (Streptococcus faecalis, milleri Streptococci, Staphylococcus aureus and Streptococcus pneumoniae) to produce L-forms bacteria.
patients and methods: In this study, the bacterial isolates were bacteriologically identified , the MIC and sub-MIC of vancomycin were determined of these isolates by using the technique of micro-broth dilution method , hypertonic special culture media designed for induction of L-forms bacteria with different concentrations of CaCl2 and MgSO4
Results: The results indicated that the species Streptococcus faecalis was the most affected one especially at the concentration of vancomycin 12.5 mg/l, where this bacterium was affected with this concentration of antibiotic and CaCl2 at the concentration of 12 g/l and 6 g/l respectively and MgSO4 at the concentration of 4g/l and provided that at the concentrations of (12+4) g/l and (6+2) g/l of CaCl2 and MgSO4. The milleri Streptococci, Staphylococcus aureus and Streptococcus pneumoniae also were affected at the same concentration of vancomycin (12.5mg/l) and at the concentration of 12 g/l of CaCl2.The milleri Streptococci and Streptococcus pneumoniae also were affected at the concentration of 4 g/l of MgSO4 and at the concentrations of (12+4) g/l and (6+2) g/l of CaCl2 and MgSO4 the milleri Streptococci was clearly affected while the Staphylococcus aureus and Streptococcus pneumoniae were affected only at the concentration of (12+4) g/l of CaCl2 and MgSO4 with availability of vancomycin at the same concentration above. The bacterial isolates also were affected at the concentration of vancomycin (6.25) mg/l with CaCl2 and MgSO4 but at lower percentage.
Conclusions: The vancomycin , CaCl2 and MgSO4 showed great effects on the induction of conversion to L-forms where the best growth of L-forms appeared when the vancomycin added at the concentration of (12.5 mg/l) to the media containing (CaCl2 and MgSO4) together especially at concentration (12 g/l) for the CaCl2 and (4 g/l) for the MgSO4.