Pneumocystis carinii Carriage among Cystic Fibrosis Patients, as Detected by Nested PCR

Abstract

A total of 137 sputa from 95 consecutive cystic fibrosis (CF) patients undergoing routine bacteriological surveillance were analyzed for Pneumocystis carinii colonization using nested PCR. Seven of 95 patients (7.4%) were PCR positive, suggesting that P. carinii carriage may exist among CF patients due to their underlying pulmonary disease.Cystic fibrosis (CF) is the most common life-shortening autosomal recessive disorder in Caucasians; it is caused by different mutations in the CF transmembrane conductance regulator gene, which is on chromosome 7 (4). Since the CF transmembrane conductance regulator gene encodes a protein functioning as a cyclic AMP-regulated chloride channel in the apical membrane of epithelial cells, several systems, including the sinopulmonary system, the gastrointestinal tract, and the male urogenital tract, can be affected in CF. The chronic bronchopulmonary manifestation of the disease poses the most serious clinical problem and causes most morbidity and mortality in CF patients. One major factor contributing to bronchopulmonary disease in CF patients is the persistent colonization and infection with typical CF bacterial pathogens, like mucoid and nonmucoid Pseudomonas aeruginosa, Staphylococcus aureus, nontypeable Haemophilus influenzae, and Burkholderia cepacia.Pneumocystis carinii is an opportunistic pathogen causing serious and even life-threatening pneumonia (P. carinii pneumonia [PCR]) in immunosuppressed patients. PCP is speculated to result either from a de novo infection or from reactivation of latent childhood infection. Seroconversion usually happens during early childhood, leading to high seroprevalence rates (3). Autopsy studies using microscopy or immunofluorescence, however, revealed no or only a very low prevalence of P. carinii, less than 1%, in adults without predisposing diseases (1, 2, 10). More sensitive methods like PCR may be able to detect even low numbers of P. carinii organisms in clinically asymptomatic but colonized persons. In a recent study it was shown that a considerable percentage (19%) of immunocompetent adult patients with primary pulmonary disease but without overt PCP were colonized by P. carinii, as established by primary and nested PCR on bronchoalveolar lavage (BAL) specimens (6). This suggests that P. carinii carriage may exist in immunocompetent patients with underlying pulmonary disease. Since it is conceivable that preexisting lung tissue damage may favor colonization by P. carinii, we hypothesized that P. carinii DNA might be detected in respiratory samples from CF patients. In a previous study on P. carinii carriage among CF patients, however, Varela et al. were not able to detect P. carinii using four different staining methods on sputa from 45 consecutive CF patients (8).To evaluate the prevalence of P. carinii colonization in CF patients, 137 sputa from 95 consecutive CF patients (43 females and 52 males; median age, 23.2 years) who were not receiving trimethoprim-sulfamethoxazole for treatment of underlying bacterial infections were exami...

Prospective Multicenter Study of Pneumocystis jirovecii Colonization among Cystic Fibrosis Patients in France

“…According to our observations, it is a reliable technique that allowed us to detect Pneumocystis colonization in 12.5% of our patients. This percentage is in agreement with data reported for CF patients from European and Brazilian areas (7.4, 21.5, and 38.2%) (22,24,26) but higher than the value of 1.3% reported by Le Gal et al for a series of 76 CF patients from French Brittany (14). As previously reported (1,17), such geographic differences in Pneumocystis carriage prevalence might be linked with the local Pneumocystis circulation, which may be lower in northern France (14; our results in Lille).…”

“…Despite technical factors that can influence the reported prevalence of Pneumocystis colonization, and according to the abovecited studies (including our results), it appears that CF is associated with lower Pneumocystis colonization rates than are other chronic pulmonary diseases (14,20,22,24,26,27,32). Three studies have reported the association of P. jirovecii and P. aeruginosa in CF patients (14,22,25), but whether Pneumocystis infection/colonization complicated CF-associated lung disease remains unclear.…”

“…Several works support a significant association of P. jirovecii colonization with diverse chronic pulmonary diseases (6,12,21). Few severe PcP cases in cystic fibrosis (CF) patients have been reported (23,25), and only some studies have reported Pneumocystis carriage, the clinical significance of which remains practically unexplored (14,(18)(19)(20)(22)(23)(24)(25)(26). The aims of the present study were therefore to evaluate the prevalence of P. jirovecii colonization during a prospective multicenter observational study, to provide information regarding the distribution of Pneumocystis genotypes, and to explore the clinical relevance of Pneumocystis colonization among CF patients in France.…”

Colonization by Pneumocystis jirovecii and Its Role in Disease

“…The prevalence of colonization varies with the population and the underlying disease. For example, Pneumocystis colonization is detected in individuals with cystic fibrosis, and the prevalence ranges from 1% to 22% (90,253,270). Patients with interstitial lung diseases appear to have a higher prevalence of colonization, especially if they are receiving corticosteroids.…”

Induced sputum for diagnosingPneumocystis cariniipneumonia in HIV patients: new data, new issues

“…Whether a positive result by PCR is indicative of the presence of a clinical disease is controversial [24][25][26][27][28][29][30]. VARGAS et al [31] reported a healthcare worker who was an asymptomatic carrier of PCP after being in contact with a patient confirmed with PCP.…”