title: Bacterial filamentation of Yersinia pestis by beta-lactam antibiotics in experimentally infected mice.
abstract: OBJECTIVE
  To identify alternatives to streptomycin for treating pneumonic plague, we evaluated beta-lactam antibiotics to treat experimental pneumonic plague in mice.
  
  
  METHODS
  Mice were exposed to a lethal inhaled dose of Yersinia pestis and treated with beta-lactam antibiotics administered every 6 hours, starting 42 hours postexposure.
  
  
  RESULTS
  The mice died or were euthanized in extremis 3 days postexposure. We observed marked bacterial filamentation of Y pestis in the tissues of mice treated with ceftazidime (10/10 mice), aztreonam (9/10 mice), or ampicillin (1/10 mice), but not in the tissues of mice treated with cefotetan, cefazolin, ceftriaxone, or saline. There was no evidence of septation of the filamentous bacteria by light or electron microscopy. The filamentous bacteria were confirmed as Y pestis based on their reactivity with rabbit anti-Y pestis F1 serum.
  
  
  CONCLUSIONS
  Marked bacterial filamentation of Y pestis can be produced in vivo by certain beta-lactam antibiotics. This antibiotic-induced morphologic change is important because filamentous bacteria in clinical samples could possibly be confused with filamentous actinomycotic organisms.
authors.affiliation: Pathology Division, USAMRIID, Ft Detrick, MD 21702-5011, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Davis
authors.forename: P
authors.initials: P
authors.lastname: Vogel
authors.forename: D L
authors.initials: DL
authors.lastname: Fritz
authors.forename: K E
authors.initials: KE
authors.lastname: Steele
authors.forename: M L
authors.initials: ML
authors.lastname: Pitt
authors.forename: S L
authors.initials: SL
authors.lastname: Welkos
authors.forename: A M
authors.initials: AM
authors.lastname: Friedlander
authors.forename: W R
authors.initials: WR
authors.lastname: Byrne
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D005260:Female; D005407:Flagella / Q000187:drug effects* / Q000648:ultrastructure; D008168:Lung / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D009026:Mortality; D010930:Plague / Q000188:drug therapy*; D013154:Spleen / Q000382:microbiology / Q000648:ultrastructure; D015010:Yersinia pestis / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams