Laboratory Aspects of Management of Chronic Pulmonary Infections in Patients with Cystic Fibrosis

In 1994, the U.S. Cystic Fibrosis Foundation sponsored a consensus conference (33) on microbiology and infectious disease in patients with cystic fibrosis (CF), a homozygous recessive disease in individuals of Caucasian descent.The organization of that conference followed the recognition that the discovery of the CF gene in 1989 was not going to yield a quick cure for CF and that chronic pulmonary infection was the primary culprit in the early mortality associated with this disease.The resulting document made recommendations for the detection, isolation, identification, and susceptibility testing of organisms recognized as significant or potentially significant in the lung diseases of this patient population.The microbial species that are clearly associated with lung disease in CF patients (CF lung disease) are relatively few, including Staphylococcus aureus, Pseudomonas aeruginosa, and Burkholderia cepacia complex (Table 1).Organisms having a secondary role in CF lung disease include respiratory viruses, such as respiratory syncytial virus and influenza virus; Haemophilus influenzae; and Aspergillus fumigatus.Mycobacterium spp.but not Mycobacterium tuberculosis, Stenotrophomonas maltophilia, and Alcaligenes xylosoxidans are being seen with increasing frequencies in CF patients, in part because of the increasing life spans of CF patients and the relentless use of antimicrobial agents in this patient population.However, the role of the latter organisms in CF lung disease has not been clearly determined.In addition, organisms that phenotypically resemble B. cepacia complex organisms (i.e., Burkholderia gladioli, Ralstonia spp., and Pandoraea spp.) are also being seen with increasing frequencies due to the use of selective media that improve the rates of recovery of B. cepacia complex isolates.These media also improve the rates of recovery of these other species.Although there are no data that suggest that these non-B.cepacia complex organisms play a role in CF lung disease, these organisms are difficult to differentiate phenotypically from B. cepacia complex.As we will review, misidentification of these seemingly harmless saprophytes as B. cepacia complex organisms may have profound consequences for the patient.This minireview discusses the state of the art in the laboratory diagnosis of the infectious agents associated with CF lung disease.