Sniffer dogs are able to detect the presence of Pseudomonas aeruginosa at very low levels, opening up the possibility for their use in screening and early antibiotic treatment to prevent lung colonisation in cystic fibrosis patients, UK researchers say.
In laboratory experiments carried out at Imperial College, London Bio Detection dogs trained by the charity Medical Detection Dogs demonstrated a high level of accuracy in differentiating in vitro samples of Pseudomonas from other pathogens that cause chronic infections in people with CF.
In the trial, the dogs were trained with a reward system to stop and sit down when presented with low levels of P. aeruginosa in liquid samples derived from sputum of CF patients.
Once trained, dogs were tested by being presented with random sequences of Pseudomonas-positive cultured samples, other cultured bacterial controls or sterile liquid, in a double-blind testing scenario.
When differentiating P. aeruginosa from other bacteria familiar to the dogs, the detection dogs had a mean sensitivity of 94.2% with a specificity of 98.5%. For P. aeruginosa versus previously unencountered bacteria, two of the three dogs maintaining sensitivity at above 90%.
When tested at dilutions of 1:1,000, sensitivity (93.8%) and specificity (94.9%) were consistently maintained; and similarly when presented with mixed, multi-organism cultures, the dogs still correctly identified P. aeruginosa with a sensitivity of 86.5% and a specificity of 84.1%.
Writing in the European Respiratory Journal, the study authors say their findings suggest that dogs may offer a more affordable and sensitive screening approach for Pseudomonas lower airway infection in people with CF.