Nitazoxanide inhibits biofilm production and hemagglutination by enteroaggregative Escherichia coli strains by blocking assembly of AafA fimbriae.
Enteroaggregative Escherichia coli (EAEC) strains have emerged as common causes of persistent diarrhea and malnutrition among children and HIV-infected persons. During infection, EAEC typically adheres to the intestinal mucosa via fimbrial adhesins, which results in a characteristic aggregative pattern. In the study described here we investigated whether the broad-spectrum antiparasitic and antidiarrheal drug nitazoxanide (NTZ) might be active against EAEC in vitro. While E. coli strains were resistant to NTZ in rich Luria-Bertani medium (MIC > 64 microg/ml), the drug was slightly inhibitory in a minimal medium supplemented with glucose (MinA-G medium; MIC, approximately 32 microg/ml). NTZ also inhibited biofilm production by strain EAEC 042 in both Dulbecco's modified Eagle's medium and MinA-G medium with a 50% inhibitory concentration of approximately 12 microg/ml. Immunofluorescence and immunoblot analyses with antibody against the major fimbrial subunit AafA of aggregative adherence fimbriae vaariant II (AAF/II) established that the numbers of AAF/II filaments on bacteria grown in the presence of NTZ were dramatically reduced. Comparative quantitative reverse transcription-PCR and reporter gene fusions (aafA::phoA) indicated that aafA expression was unaffected by NTZ, while aggR transcript levels and aggR::lacZ expression were increased approximately 10- and 2.5-fold, respectively, compared with that for the untreated controls. More generally, NTZ inhibited hemagglutination (HA) of red blood cells by the non-biofilm-producing strain JM221 expressing either AAF/I or type I fimbriae. Our findings suggest that the inhibitory action of NTZ on biofilm formation and HA is likely due to inhibition of fimbrial assembly. Antimicrobial agents that inhibit the assembly or function of fimbrial filaments should be good candidates for the prevention of infection.
Shamir
Eliah R
ER
Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia 22908, USA.
Warthan
Michelle
M
Brown
Sareena P
SP
Nataro
James P
JP
Guerrant
Richard L
RL
Hoffman
Paul S
PS
D018830:Adhesins, Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D000890:Anti-Infective Agents / Q000494:pharmacology; D001483:Base Sequence; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002648:Child; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D003967:Diarrhea / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology* / Q000517:prevention & control; D010861:Fimbriae, Bacterial / Q000187:drug effects / Q000502:physiology; D005798:Genes, Bacterial; D006384:Hemagglutination / Q000187:drug effects; D006801:Humans; D009154:Mutation; D009574:Nitro Compounds; D013844:Thiazoles / Q000494:pharmacology*; D014774:Virulence / Q000187:drug effects / Q000235:genetics
C108511:AafA protein, E coli; D018830:Adhesins, Escherichia coli; D000890:Anti-Infective Agents; D017931:DNA Primers; D004269:DNA, Bacterial; D009574:Nitro Compounds; D013844:Thiazoles; C041747:nitazoxanide