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Effect of penicillin and chloramphenicol on the growth and endotoxin release by N. meningitidis
M C Mellado1, R Rodríguez-Contreras, A Mariscal
1Department of Preventive Medicine, School of Medicine, University of Granada, Spain.
Abstract:
The action of two antibiotics, penicillin and chloramphenicol, on bacterial growth and endotoxin liberation was studied in 18 strains of Neissevia meningitidis isolated from blood and CSF of patients with meningococcal infections. The antibiotics were administered both separately and in combined form in doses equivalent to 1 MIC and 100 MIC. Penicillin was found to produce a faster and more intense bactericidal effect than chloramphenicol during the first hour, whereas at 12 h these differences were not significant. This could explain the initial worsening observed in some infected patients when large doses of penicillin are administered. An increased liberation of endotoxin after adding penicillin was observed in six of the strains studied, whereas the remaining 12 did not show significant increases. The six strains (belonging to serogroup B) were known to have an enhanced capacity for spontaneous endotoxin liberation.
Insights
Penicillin and chloramphenicol impact meningococcal growth and endotoxin release. Penicillin
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Neisseria meningitidis causes severe infections.
- Antibiotic treatment is crucial for managing meningococcal disease.
- Endotoxin release can exacerbate infection severity.
Purpose of the Study:
- To investigate the effects of penicillin and chloramphenicol on bacterial growth.
- To assess the impact of these antibiotics on endotoxin liberation.
- To correlate findings with clinical observations in meningococcal infections.
Main Methods:
- Studied 18 Neisseria meningitidis strains from patient samples (blood and CSF).
- Administered penicillin and chloramphenicol separately and in combination.
- Tested antibiotic concentrations at 1 Minimum Inhibitory Concentration (MIC) and 100 MIC.
Main Results:
- Penicillin demonstrated a more rapid bactericidal effect than chloramphenicol within the first hour.
- At 12 hours, the bactericidal differences between antibiotics were not significant.
- Increased endotoxin liberation was observed with penicillin in six strains, particularly those from serogroup B known for spontaneous endotoxin release.
Conclusions:
- The rapid bactericidal action of penicillin may contribute to initial clinical worsening in some patients.
- Specific Neisseria meningitidis strains, especially serogroup B, exhibit varied responses to antibiotic-induced endotoxin release.
- Understanding these antibiotic-host-pathogen interactions is vital for optimizing treatment strategies.