title: In vitro activity of bioactive extracts from rare actinomycetes against multi-drug resistant Streptococcus pneumoniae.
abstract: OBJECTIVE
  In this study, we investigated the in vitro potential of the bioactive extracts from five putatively novel species of actinomycetes isolated from the Indian hot desert against multi-drug resistant (MDR) Streptococcus pneumoniae.
  
  
  RESULTS
  The antimicrobial activity of 10 different extracts was evaluated against S. pneumoniae strains with, erm(B) and mef(E) genes as well as fluoroquinolone-resistant (FQ(R) ) strains using the micro-broth dilution method. Of these 10 extracts, four exhibited good to excellent anti-S. pneumoniae activity with minimum inhibitory concentrations (MICs) ranging from 0·125 to 8 μg ml(-1) . The time-kill kinetics study showed that these extracts killed the pathogens in 2-8 h. In vitro cell-free transcription/translation of luciferase gene using S30 bacterial extract and TNT mammalian ribosome indicated that they inhibited bacterial ribosomes at much lower concentrations than those required to inhibit the mammalian ribosomes.
  
  
  CONCLUSIONS
  This study demonstrates that these are potent concentration-dependent bactericidal metabolites with 16-fold higher in vitro activity than levofloxacin against MDR S. pneumoniae.
  
  
  CONCLUSIONS
  Metabolites from actinomycetes can be excellent inhibitors of MDR S. pneumoniae. Considering the in vitro efficacy of these crude extracts against S. pneumoniae MDR spp., once purified these can be used against streptococcal pathogens causing community-acquired pneumonia.
authors: School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India.
authors: K
authors: K
authors: Tiwari
authors: Centre for Drug Design, Discovery & Development (CD4), SRM University, Sonepat, India.
authors: V S
authors: VS
authors: Raj
authors: Department of Infectious Diseases, New Drug Discovery Research, Ranbaxy Research Laboratories, R & D III, Gurgaon, India.
authors: D J
authors: DJ
authors: Upadhyay
authors: School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India.
authors: R K
authors: RK
authors: Gupta
mesh_terms: D039903:Actinobacteria / Q000737:chemistry* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017714:Community-Acquired Infections / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents
keywords: S. pneumoniae; antimicrobial susceptibility; bioactive extracts; multi-drug resistance; rare actinomycetes; time-kill kinetics