Summary (continued)
Polymerase chain reaction analyses revealed the presence of invA, sopB and bcfC in all six isolates, whereas sopE1 and gipA were absent. All six isolates were resistant to lincomycin and streptomycin, but all were susceptible to ciprofloxacin, colistin sulphate and gentamicin. Among the S. Typhimurium isolates, seven resistance profiles were identified: penicillins, aminoglycosides, fluoroquinolones, lincosamides, phenicols, tetracyclines and sulphonamides; four resistance profiles were identified in the isolates of S. Braenderup and S. Lomita: aminoglycosides, fluoroquinolones, lincosamides and polymyxin. Thus, the distribution of resistance to the antibiotics was largely dependent on serotype identity. The presence of invA, avrA, ssaQ, mgtC, siiD, sopB and bcfC was associated with resistance to chloramphenicol; invA, sopB and bcfC with resistance to streptomycin and lincosamide; and invA and sodC1 with resistance to trimethoprim–sulfamethoxazole. The identification of serotypes S. Typhimurium, S. Braenderup and S. Lomita in the squab samples has important implications because these serotypes are significant causes of food poisoning and enteric fever in humans.