title: Antibiotic susceptibility of cocultures in polymicrobial infections such as peri-implantitis or periodontitis: an in vitro model.
abstract: BACKGROUND
  Although polymicrobial infections, such as peri-implantitis or periodontitis, were postulated in the literature to be caused by synergistic effects of bacteria, these effects remain unclear looking at antibiotic susceptibility. The aim of this study is to compare the antibiotic susceptibilities of pure cultures and definite cocultures.
  
  
  METHODS
  Laboratory strains of Aggregatibacter actinomycetemcomitans (Aa) (previously Actinobacillus actinomycetemcomitans), Capnocytophaga ochracea (Co), and Parvimonas micra (Pm) (previously Peptostreptococcus micros) were cultivated under anaerobic conditions, and their susceptibilities to 10 antibiotics (benzylpenicillin G, ampicillin, amoxicillin, ampicillin/sulbactam, amoxicillin/clavulanic acid, minocycline, metronidazole, linezolid, azithromycin, and moxifloxacin) were tested using the Epsilometertest. Cocultures, each consisting of two or three bacteria, were treated analogously.
  
  
  RESULTS
  All four cocultures showed lower susceptibilities to azithromycin and minocycline than to pure cultures. The coculture Aa-Co showed a lower susceptibility to moxifloxacin as did the coculture Aa-Pm to benzylpenicillin G; the coculture Co-Pm showed a lower susceptibility to amoxicillin, amoxicillin/clavulanic acid, metronidazole, and benzylpenicillin G. However, the coculture Co-Pm showed a higher susceptibility to ampicillin, linezolid and moxifloxacin as did Aa-Pm and Aa-Co-Pm to linezolid.
  
  
  CONCLUSIONS
  In addition to established in vitro assays, it was demonstrated that antimicrobial cocultures caused antibiotic susceptibilities that differed from those of pure cultures. Bacterial cocultures frequently showed lowered susceptibilities to antibiotics.
authors.affiliation: Department for Oral Surgery; Johannes Gutenberg-University, Mainz, Germany. anastasia.mouratidou@unimedizin-mainz.de
authors.forename: Anastasia
authors.initials: A
authors.lastname: Mouratidou
authors.forename: Julia
authors.initials: J
authors.lastname: Karbach
authors.forename: Bernd
authors.initials: B
authors.lastname: d'Hoedt
authors.forename: Bilal
authors.initials: B
authors.lastname: Al-Nawas
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000189:Actinobacillus Infections / Q000188:drug therapy; D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects; D000658:Amoxicillin / Q000494:pharmacology; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D001372:Aza Compounds / Q000494:pharmacology; D017963:Azithromycin / Q000494:pharmacology; D002206:Capnocytophaga / Q000187:drug effects; D018920:Coculture Techniques; D060085:Coinfection / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D000069349:Linezolid; D008795:Metronidazole / Q000494:pharmacology; D056265:Microbial Interactions / Q000187:drug effects; D008911:Minocycline / Q000494:pharmacology; D000077266:Moxifloxacin; D023303:Oxazolidinones / Q000494:pharmacology; D010400:Penicillin G / Q000494:pharmacology; D010462:Peptostreptococcus / Q000187:drug effects; D057873:Peri-Implantitis / Q000188:drug therapy / Q000382:microbiology*; D010518:Periodontitis / Q000188:drug therapy / Q000382:microbiology*; D011804:Quinolines / Q000494:pharmacology; D013407:Sulbactam / Q000494:pharmacology
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D023303:Oxazolidinones; D011804:Quinolines; D008795:Metronidazole; C035444:sultamicillin; D019980:Amoxicillin-Potassium Clavulanate Combination; D000667:Ampicillin; D000658:Amoxicillin; D017963:Azithromycin; D008911:Minocycline; D000069349:Linezolid; D010400:Penicillin G; D013407:Sulbactam; D000077266:Moxifloxacin