Antibiotic resistance in faecal bacteria (Escherichia coli, Enterococcus spp.) in feral pigeons

To determine the presence of antibiotic-resistant faecal Escherichia coli and Enterococcus spp. in feral pigeons (Columba livia forma domestica) in the Czech Republic.

Cloacal swabs of feral pigeons collected in the city of Brno in 2006 were cultivated for antibiotic-resistant E. coli. Resistance genes, class 1 and 2 integrons, and gene cassettes were detected in resistant isolates by polymerase chain reaction (PCR). The samples were also cultivated for enterococci. Species status of enterococci isolates was determined using repetitive extragenic palindromic-PCR. Resistance genes were detected in resistant enterococci by PCR. E. coli isolates were found in 203 of 247 pigeon samples. Antibiotic resistance was recorded in three (1·5%, n(E. coli) =203) isolates. Using agar containing ciprofloxacin, 12 (5%, n(samples) =247) E. coli strains resistant to ciprofloxacin were isolated. No ESBL-producing E. coli isolates were detected. A total of 143 enterococci were isolated: Ent. faecalis (36 isolates), Ent. faecium (27), Ent. durans (19), Ent. hirae (17), Ent. mundtii (17), Ent. gallinarum (12), Ent. casseliflavus (12) and Ent. columbae (3). Resistance to one to four antibiotics was detected in 45 (31%) isolates. Resistances were determined by tetK, tetL, tetM, tetO, aac(6')aph(2''), ant(4')-Ia, aph(3')-IIIa, ermB, pbp5, vanA and vanC1 genes.

Antibiotic-resistant E. coli and Enterococcus spp. occurred in feral pigeons in various prevalences.

Feral pigeon should be considered a risk species for spreading in the environment antimicrobial resistant E. coli and enterococci.