Pseudomonas aeruginosa cross-infection in cystic fibrosis

Abstract

In this Aug 18 commentary, D Geddes1Geddes DM Of isolates and isolation: Pseudomonas aeruginosa in adults with cystic fibrosis.Lancet. 2001; 358: 522-523Summary Full Text Full Text PDF PubMed Scopus (23) Google Scholar addresses the topic of Pseudomonas aeruginosa cross-infection in cystic fibrosis, and identifies several key questions: how often and why it happens, how much does cross-infection contribute to morbidity and mortality, and what actions should be taken to prevent cross-infection. We have documented clear evidence of cross-infection at two UK adult cystic fibrosis centres.2Jones AM Govan JRW Doherty CJ et al.Spread of a multiresistant strain of Pseudomonas aeruginosa in an adult cystic fibrosis clinic.Lancet. 2001; 358: 557-558Summary Full Text Full Text PDF PubMed Scopus (201) Google Scholar, 3McCallum SJ Corkhill J Gallagher M Ledson MJ Hart CA Walshaw MJ Superinfection with a transmissible strain of Pseudomonas aeruginosa in adults with cystic fibrosis chronically colonised by P aeruginosa.Lancet. 2001; 358: 558-560Summary Full Text Full Text PDF PubMed Scopus (130) Google Scholar Although previously thought to be rare, P aeruginosa cross-infection is an emerging complication in cystic fibrosis. In studies using molecular fingerprinting techniques researchers have reported compelling evidence of cross-infection outbreaks in the UK and other countries.2Jones AM Govan JRW Doherty CJ et al.Spread of a multiresistant strain of Pseudomonas aeruginosa in an adult cystic fibrosis clinic.Lancet. 2001; 358: 557-558Summary Full Text Full Text PDF PubMed Scopus (201) Google Scholar, 3McCallum SJ Corkhill J Gallagher M Ledson MJ Hart CA Walshaw MJ Superinfection with a transmissible strain of Pseudomonas aeruginosa in adults with cystic fibrosis chronically colonised by P aeruginosa.Lancet. 2001; 358: 558-560Summary Full Text Full Text PDF PubMed Scopus (130) Google Scholar, 4Armstrong DS Nixon G Carlin J Carzino R Grimwood K Long term outbreak of transmissible virulent strain of Pseudomonas aeruginosa in a paediatric cystic fibrosis clinic.Pediatr Pulmonol. 2000; 20: 285Google Scholar, 5Hunfeld KP Schmidt C Krackhardt B et al.Risk of Pseudomonas aeruginosa crosscolonisation in patients with cystic fibrosis within a holiday camp: a molecularepidemiological study.Wien Klin Wochenschr. 2000; 112: 329-333PubMed Google Scholar Currently, most UK cystic fibrosis centres have not surveyed their clinics with reliable typing techniques for P aeruginosa. Geddes is wrong to assume that P aeruginosa cross-infection remains rare. The true extent of this problem in UK centres is, at present, unknown. Only widespread microbiological surveillance, including a form of molecular fingerprinting, will give us the answer. The assumption by Geddes that P aeruginosa outbreaks are due to a simple breakdown in cross-infection control measures is clearly incorrect. If such a breakdown had occurred, spread of many different strains would be expected within cystic fibrosis centres; however, the problem is limited to a few rogue strains. Despite widespread bacterial surveillance of the hospital inpatient and outpatient environments, we find no reservoir for the transmissible strains. The only samples that yielded such strains were patient sputa. The most likely mode of spread is direct patient-to-patient contact. How much P aeruginosa cross-infection contributes to morbidity and mortality is currently unknown. As Geddes points out, intuitively cross-infection with a multiresistant strain must be a disadvantage. The ability of such strains to cause superinfection3McCallum SJ Corkhill J Gallagher M Ledson MJ Hart CA Walshaw MJ Superinfection with a transmissible strain of Pseudomonas aeruginosa in adults with cystic fibrosis chronically colonised by P aeruginosa.Lancet. 2001; 358: 558-560Summary Full Text Full Text PDF PubMed Scopus (130) Google Scholar a further worrying feature. Increased virulence in association with transmissible P aeruginosa strain has also been reported.4Armstrong DS Nixon G Carlin J Carzino R Grimwood K Long term outbreak of transmissible virulent strain of Pseudomonas aeruginosa in a paediatric cystic fibrosis clinic.Pediatr Pulmonol. 2000; 20: 285Google Scholar P aeruginosa cross-infection cannot be ignored. Widespread microbiological surveillance is justified and essential, despite the potential cost involved to gather the necessary information to prevent spread and possibly to avert further outbreaks. Pseudomonas aeruginosa cross-infection in cystic fibrosisAuthor's reply Full-Text PDF