Pneumocystis jirovecii dihydropteroate synthase genotypes in immunocompetent infants and immunosuppressed adults, Amiens, France

Abstract

To date, investigations of Pneumocystis jirovecii circulation in the human reservoir through the dihydropteroate synthase (DHPS) locus analysis have only been conducted by examining P. jirovecii isolates from immunosuppressed patients with Pneumocystis pneumonia (PCP). Our study identifies P. jirovecii genotypes at this locus in 33 immunocompetent infants colonized with P. jirovecii contemporaneously with a bronchiolitis episode and in 13 adults with PCP; both groups of patients were monitored in Amiens, France. The results have pointed out identical features of P. jirovecii DHPS genotypes in the two groups, suggesting that in these groups, transmission cycles of P. jirovecii infections are linked. If these two groups represent sentinel populations for P. jirovecii infections, our results suggest that all persons parasitized by P. jirovecii, whatever their risk factor for infection and the form of parasitism they have, act as interwoven circulation networks of P. jirovecii.

Figure 1

Identification of Pneumocystis jiroveci dihydropteroate synthase (DHPS) genotypes. Electrophoresis on 1.5% agarose gel of DHPS polymerase chain reaction products after digestion with AccI (upper line) and HaeIII (lower line). M, molecular weight marker (123 Gibco BRL; Cergy Pontoise, France). Lane 1: double mutant genotype; lanes 2 and 5: wild genotype; lane 3: mixed infection with a wild genotype and a mutant genotype that has the mutation at nucleotide position 165; lane 4: mixed infection with a wild genotype and a mutant genotype which has the mutation at nucleotide position 171.

Figure 2

Frequencies of Pneumocystis jiroveci dihydropteroate synthase mutants in patients with Pneumocystis pneumonia and who had no prior sulfonamide exposure, from diverse European cities. Amiens, France (the present study), Paris (13), Lyon (12), Copenhagen (4), Milan, Italy (2), Rome (11), and London (35).