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In vitro antibiotic synergy against Flavobacterium meningosepticum: implications for therapeutic options
M C Di Pentima1, E O Mason, S L Kaplan
1Department of Pediatrics, Texas Children's Hospital, Houston 77030, USA.
Abstract:
Flavobacterium meningosepticum is an unusual, highly resistant, gram-negative bacillus that is associated with neonatal meningitis and nursery outbreaks of meningitis. The optimal therapy for this infection is not known. We successfully treated three neonates with intravenous vancomycin and rifampin. We determined the in vitro activity of meropenem, ciprofloxacin, vancomycin, linezolid (PNU-100766), and rifampin, alone and in combination, against four isolates of F. meningosepticum from neonates with sepsis and meningitis. MICs were determined by tube dilution, and fractional inhibitory concentrations were calculated with use of the checkerboard microtiter dilution technique. Synergy was observed between rifampin and vancomycin against three isolates, while combinations of vancomycin, ciprofloxacin, and linezolid showed an additive effect against all isolates. These results support the clinical evidence that the combination of vancomycin and rifampin is an appropriate regimen for neonatal meningitis due to F. meningosepticum. The combination of meropenem and vancomycin was antagonistic. The clinical efficacy of combinations including ciprofloxacin, newer quinolones, or linezolid for treating F. meningosepticum meningitis deserves further study.
Insights
Vancomycin and rifampin effectively treated neonatal meningitis caused by the resistant bacterium Flavobacterium meningosepticum. In vitro studies confirmed synergy between these antibiotics, supporting their use in clinical settings.
Area of Science:
- Microbiology and Infectious Diseases
- Neonatal Medicine
- Pharmacology
Background:
- Flavobacterium meningosepticum is a rare, multidrug-resistant Gram-negative bacterium.
- This pathogen is a significant cause of neonatal meningitis and hospital-acquired infections.
- Optimal therapeutic strategies for F. meningosepticum infections remain undefined.
Purpose of the Study:
- To evaluate the in vitro antimicrobial activity of various agents against Flavobacterium meningosepticum.
- To assess the synergistic, additive, or antagonistic effects of antibiotic combinations.
- To provide evidence supporting effective treatment regimens for neonatal meningitis.
Main Methods:
- Minimum Inhibitory Concentrations (MICs) were determined using standard tube dilution.
- Fractional Inhibitory Concentrations (FICs) were calculated via checkerboard microtiter assays.
- Antibiotic susceptibility testing included meropenem, ciprofloxacin, vancomycin, linezolid, and rifampin.
Main Results:
- Vancomycin and rifampin demonstrated synergistic activity against three of four F. meningosepticum isolates.
- Combinations of vancomycin with ciprofloxacin or linezolid showed additive effects.
- Meropenem and vancomycin exhibited antagonistic interactions.
Conclusions:
- The combination of vancomycin and rifampin is a promising therapeutic option for neonatal meningitis caused by F. meningosepticum.
- Clinical success in three neonates supports this combination regimen.
- Further research is warranted for novel agents like ciprofloxacin and linezolid.