Healthcare related transmission of Pneumocystis pneumonia: From key insights toward comprehensive prevention

Abstract

In at risk populations, Pneumocystis pneumonia (PCP) may occur as a solitary event as well as in a cluster- or outbreak setting due to interpatient transmission of Pneumocystis jirovecii. Despite the data and insights obtained from studies of outbreaks of PCP, the development and implementation of comprehensive recommendations for the prevention of healthcare related transmission of P. jirovecii have been delayed. Both optimization of chemoprophylaxis strategies as well as combination with prudent use of isolation precautions are warranted to achieve this goal. The rationale of the available measures for the prevention of PCP should be viewed in the context of what is currently known about the complex biology and epidemiology of P. jirovecii. From there, phased but practical prevention strategies can be deducted to balance the efforts, costs and negative consequences of chemoprophylaxis and isolation precautions with the beneficial effect of preventing healthcare related transmission of P. jirovecii and development of PCP.

No Change of Pneumocystis jirovecii Pneumonia after the COVID-19 Pandemic: Multicenter Time-Series Analyses

“…However, the fungal load (relatively high Ct values with ≥30 or small copies with 10-4000/µL in PCR tests) of P. jirovecii exhaled in the air is lower than with viral infections [31,34,36,37,41,42], and potentially, not all the asymptomatically acquitted P. jirovecii propagules can induce sustained PCP [20,27,31]. In addition, the airborne-transmission of P. jirovecii should require common contact with contaminated air, indicating that transmission is much more probable with people who meet frequently [27,31,42,77,78]. Reinforced social distancing and nationwide infection control measures inversely increased common close contact within the home [7].…”

“…The main reason for the persistence of the PCP diagnosis during the COVID-19 pandemic would probably be associated with the much lower transmission probability and infectivity of P. jirovecii in the air compared to airborne-transmitted viruses (estimated basic reproduction number [R0] during the early stages of an epidemic or pandemic: 1.5-5.5 for SARS-CoV-2, 1.3-23.0 for influenza, 3.0 for RSV, and 3.7-57.0 for measles) [27,31,[72][73][74][75][76].…”

“…Pneumocystis jirovecii is an important respiratory opportunistic pathogen that contributes to critical illness and poor outcomes in severe immunocompromised transplant recipients and patients with acquired immunodeficiency syndrome [20]. Even though P. jirovecii pneumonia (PCP) may occur after environmental acquisition [20][21][22][23][24][25][26], accumulating evidence has established person-to-person transmission (possibly airborne) or asymptomatic carriers (colonization) of P. jirovecii, even in the general population, strongly supported by many outbreaks in healthcare-associated and community environments [27][28][29][30][31][32][33][34][35][36][37]. Several seroepidemiologic surveys revealed that the majority (70-80%) of healthy children were seropositive for P. jirovecii [38][39][40].…”

Airborne Interindividual Transmission of Pneumocystis jirovecii

“…This indicates that P. jirovecii can be exhaled and spread from both PCP patients and colonized patients. However, whether colonized patients represent infectious sources at the same level as PCP patients is still an open question considering the difference in pulmonary fungal burden [47,50]. The major findings of P. jirovecii genotyping clinical samples and air samples are summarized (Table 2).…”

“…Further, precautions should be proposed to prevent P. jirovecii transmission from patients developing PCP who may be highly contagious. Whether precautionary measures should be implemented for colonized patients or healthcare workers who may have a role in the transmission chain remains a subject of debate [33,50,58]. Through In a different approach, the French Hygiene Society recommends that susceptible patients should wear a mask when encountering all other patients [59].…”