Table 5.

Studies describing antimicrobial resistance in Pneumocystis jirovecii.

Author	Year	Resistance mechanism	Antifungal agent affected	Clinical significance
Argy et al.	2018	Cytochrome b (cyt b) mutation (A144V)	Atovaquone	Failure of atovaquone prophylaxis in heart transplant patients
Singh et al.	2019	DHPS mutations: novel non-synonymous nucleotide substitution at position 288 (G → A), resulting in amino acid change (Val96Ile)	Trimethoprim–sulfamethoxazole	3 of 12 (25%) HIV-positive adult patients with HIV and PJP were found to have this mutation and died despite treatment with trimethoprim–sulfamethoxazole, while the other 9 survived
Singh et al.	2015	Mutations (nucleotide substitutions) in the dihydrofolate reductase (DHFR) gene	Trimethoprim–sulfamethoxazole	Among a mixed population (HIV-positive and HIV-negative), treated for PJP with trimethoprim–sulfamethoxazole, 2/14 (14%) of patients with DHFR mutations died; both had co-infections, and the DHFR mutations were of uncertain significance

DHFR, dihydrofolate reductase; DHPS, dihydropteroate synthase; HIV, human immunodeficiency virus; PJP, Pneumocystis jirovecii pneumonia.