Bacterial filamentation of Yersinia pestis by beta-lactam antibiotics in experimentally infected mice.
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.
Davis
K J
KJ
Pathology Division, USAMRIID, Ft Detrick, MD 21702-5011, USA.
Vogel
P
P
Fritz
D L
DL
Steele
K E
KE
Pitt
M L
ML
Welkos
S L
SL
Friedlander
A M
AM
Byrne
W R
WR
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
D000900:Anti-Bacterial Agents; D047090:beta-Lactams