Non-steroidal anti-inflammatory drugs ketorolac and etodolac can augment the treatment against pneumococcal meningitis by targeting penicillin-binding proteins.

Abstract

Streptococcus pneumoniae is the principal etiological agent of acute bacterial meningitis (ABM) which has fatal outcome in children and elderly. Due to poor blood-brain barrier (BBB) permeation, conventional β-lactam antibiotics fail to establish the requisite bactericidal concentration in central nervous system leading to resistance in meningeal infections. The present study intended to identify potential therapeutic alternatives against Streptococcal meningitis. Virtual screening, pharmacokinetics/pharmacodynamics (PK/PD) and anti-bacterial evaluations were employed to screen potential drugs. Molecular docking and structural dynamics simulations were performed to analyze the binding affinity and interaction stability of the drugs against the conventional Penicillin binding protein (PBP) targets. Screened drugs were also checked for interactions with other possible Streptococcal targets and relevant host targets. Non-steroidal anti-inflammatory drugs (NSAIDs) ketorolac and etodolac exhibiting high BBB-permeation and anti-bacterial potency were identified. Ketorolac and etodolac possessed uniform binding affinities against PBP1A, PBP2X, PBP2B and PBP3 with low inhibition constants (<50μM). Against PBP2B and PBP3, higher binding affinities were observed for ketorolac (-6.45 and -6Kcal/mol respectively) and etodolac (-6.36 and -6.55Kcal/mol respectively) than penicillin (-5.95 and -5.85Kcal/mol respectively) and cefotaxime (-5.08 and -5.07Kcal/mol respectively). The binding affinities were contributed by conventional H-bonds and non-canonical interactions with active site residues of PBPs. Structural dynamics simulations further indicated the overall stability of the drug-bound complexes through minimal overall average root-mean square fluctuations (RMSFs) (<1.0Å). The average binding affinities of Ketorolac and Etodolac with PBPs were marginally higher than other Streptococcal targets and comparable to their conventional inflammatory targets. Pharmacological and structural profiles indicated that ketorolac and etodolac can potentially subdue the cause and effects of streptococcal meningitis and hence encourage experimental validations.