Exhaled Pneumocystis jirovecii output and detection of asymptomatic exhalation by facemask sampling in HIV-uninfected, immunocompromised patients
Holmes, Christopher Koo, Sharon Perera, Nelun Barer, Michael R
Holmes, Christopher
Koo, Sharon
Perera, Nelun
Barer, Michael R
Abstract
Background: Pneumocystis jirovecii pneumonia (PJP) transmission is poorly defined. Previous studies have sampled air of rooms occupied by HIV-infected patients with PJP, while natural and direct exhalations of HIV-uninfected subjects remain under-investigated. Here, clinical facemasks were used to examine and quantify potential P. jirovecii exhalations from HIV-uninfected patients with suspected PJP and to determine whether pathogen exhalation was definable clinically or radiologically.
Methods: Forty-five patients in Leicester (England), highly suspected of having PJP based on European Conference on Infections in Leukaemia (ECIL-5) guidelines, each wore one facemask carrying a gelatine/PVA sampling matrix for 1 h while respiring normally. Mask contamination with P. jirovecii was assessed using a modified quantitative polymerase chain reaction targeting mitochondrial large subunit (MtLSU). Radiological findings on chest X-ray (CXR) and computed tomography (CT) were graded and analysed for correlation with P. jirovecii signals alongside relevant clinical and laboratory findings.
Results: P. jirovecii was detected in seven of 20 patients diagnosed with PJP and three of 19 patients with suspected but undiagnosed PJP. The median captured signal was 8.59 × 104 MtLSU copies/mask (interquartile range (IQR) = 3.01 × 105-1.81 × 104). Blood β-D-glucan test results correlated with the mask detection data (r = 0.65; P<0.0001) but other clinical indices and radiological features did not. Five of the 10 P. jirovecii-exhalers exhibited normal CXR with a median exhalation burden 1.28 × 105 copies/mask (IQR = 1.51 × 105-2.27 × 104). Two P. jirovecii-exhalers (7.64 × 104 copies/mask) were asymptomatic.
Conclusion: P. jirovecii was exhaled sufficiently during normal respiration to be detectable in facemasks worn by HIV-uninfected patients. Neither clinical nor radiological features correlated with P. jirovecii exhalation.
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Date
2022-12-12
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Abdulwhhab, M. T., Holmes, C. W., Mutuyimana, J., Koo, S. S. F., Wisniewska, A., Auty, J., Perera, N., & Barer, M. R. (2023). Exhaled Pneumocystis jirovecii output and detection of asymptomatic exhalation by facemask sampling in HIV-uninfected, immunocompromised patients. The Journal of hospital infection, 132, 20–27. https://doi.org/10.1016/j.jhin.2022.12.003