An improved method of isolating Pneumocystis carinii from infected rat lungs

Area of Science:

• Medical Mycology
• Parasitology
• Infectious Diseases

Background:

• Pneumocystis carinii pneumonia (PCP) is a significant opportunistic infection.
• Accurate enumeration of Pneumocystis carinii stages is crucial for understanding infection dynamics and treatment efficacy.
• Existing isolation methods often result in parasite clumping and difficulty in distinguishing between different life stages.

Purpose of the Study:

• To develop an improved method for isolating Pneumocystis carinii from infected rat lungs.
• To enable the enumeration of both trophozoite and cyst stages of Pneumocystis carinii.
• To characterize the density of different Pneumocystis carinii stages and host lung debris.

Main Methods:

• Macerated infected rat lung was suspended in a modified calcium, magnesium-free Hanks' balanced salts solution with G-acid to reduce clumping.
• The suspension underwent digestion using a buffer containing calcium, magnesium, collagenase, hyaluronidase, and deoxyribonuclease.
• Parasites were separated from debris using Percoll density gradients based on differential densities of trophozoites, cysts, and host lung material.

Main Results:

• The new method effectively reduced clumping of parasites and host lung material.
• It allowed for the distinct enumeration of both trophozoites and cysts.
• Density studies revealed trophozoites and non-nucleated cysts at 1.028 g/ml, nucleated cysts at 1.030 g/ml, and host debris at 1.040 g/ml.

Conclusions:

• This optimized isolation technique provides relatively clump-free suspensions of infected rat lung.
• The method facilitates the accurate enumeration of Pneumocystis carinii trophozoites and cysts.
• The characterization of nucleated cysts and their density is a significant outcome of this study.