Royal College are held in September ... grams in Canada accredited by ... BSc, RT for her technical and photo- ... SCHUSTER FL: Intranuclear virus-like.
Symbiosis of Pneumocystis carinii and cytomegalovirus in a case of fatal pneumonia PIERRE ERNST, MD MOY-FONG CHEN, MD NAT-SAN WANG, MD MANUEL Coslo, MD Pneumocystis carinii pneumonia is a frequent complication in the immunocompromised host. It is often associated with infections due to other opportunistic organisms, most commonly cytomegalovirus.'3 In all 15 cases of P. carinii pneumonia observed over 18 months in homosexual men in California there was evidence of past or concomitant cytomegalovirus infection.4 In one case of fatal pneumonia ascribed to P. carinii infection electron-dense particles, presumed to be cytomegalovirus particles, were seen within the Pneumocystis organisms.5 We present a case of combined P. carinji and cytomegalovirus pneumonia in a young Haitian man that adds further evidence to the possibility of symbiosis between cytomegalovirus and P. carinii.
pattern. Arterial blood gas values were: pH 7.50, oxygen tension (Po2) 60 mm Hg and carbon dioxide tension (Pco2) 24 mm Hg. Over the next 10 days the hypoxemia worsened and the chest roentgenogram showed complete opacification of both lung fields, suggestive of interstitial and alveolar edema. An open lung biopsy was performed 3 weeks after admission, and when P. carinii was identified histologically therapy with trimethoprim-sulfamethoxazole was instituted. Repeated blood, urine and stool cultures were negative except for a light growth of Staphylococcus aureus from one stool sample. There was mild normochromic normocytic anemia throughout his illness and moderate leukocytosis. Protein elec-
trophoresis had normal results except for a serum albumin level of 2.0 g/dl. There was a mild elevation of liver enzyme levels in the serum. The patient's respiratory stat us continued to deteriorate. The arterial blood gas values while the patient was breathing 100% oxygen were: pH 7.06, Po2 53 mm Hg and Pco2 100 mm Hg. The patient died after nearly 5 weeks in hospital. Pathological investigation Methods: An autopsy was performed 12 hours after death. For light microscopy the lungs were inflated and fixed with 10% buffered formaldehyde solution. Paraffinembedded sections were stained with hematoxylin-eosin and Grocott's sil-
Case report
Clinical course
A 34-year-old, married, Haitian man had immigrated to Canada 10 years previously. He had been well all his life until he started suffering from chronic diarrhea and lost approximately 9 kg of body weight in 10 months. He was admitted to hospital for investigation. One week after admission he complained of dyspnea. A physical examination revealed fever, tachypnea and scattered rales. A chest roentgenogram showed a diffuse reticulonodular From the respiratory division, department of medicine, and the department of pathology, Royal Victoria Hospital and McGill University, Montreal Reprint requests to: Dr. Pierre Ernst, Department of epidemiology and health, McGill University, 3775 University St., Montreal, PQ H3A 2B4
FIG. 1-Typical intranuclear inclusions of cytomegalovirus (arrow) and foamy exudates in alveoli. (Hematoxylin-eosin; X5041.) CAN MED ASSOC J, VOL. 128, MAY 1, 1983
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ver methenamine stains. For elec- nm (Fig. 3). Large, thick-walled an outer dense zone. An additional tron microscopy blocks of lung tis- cysts contained trophozoite-like bod- external limiting membrane encirsue 1 to 2 mm wide were fixed in 3% ies 1 to 1.5 .m in diameter. Occa- cled each intracytoplasmic particle. phosphate-buffered glutaraldehyde sional cysts had a small defect in Extrusion of cytoplasmic particles solution, postfixed in 1% osmium their wall (Fig. 4). Some alveolar through a defect in the cell memtetroxide Palade buffer solution, lining cells contained intranuclear brane was occasionally found dehydrated with graded acetone and and intracytoplasmic particles 76 to (Fig. 5). embedded in epoxy resin (Epon). 86 nm in diameter; the particles in Sections 1 to 2 gm thick were cut the nucleus consisted of a dense Discussion with an ultramicrotome, stained central core about 64 nm in diameThe course of this patient's respwith 1% toluidine blue and exam- ter surrounded by an inner halo and ined with the light microscope. Thinner sections, 60 to 100 nm thick, were stained with both uranyl acetate and lead citrate and examined with an electron microscope. Gross findings: Skin lesions included a healed 6-cm long thoracotomy scar, chest tube drainage sites and superficial decubitus ulcers on the buttocks. The lungs weighed 2000 g in total and showed bilateral fibrinous pleuritis with pleural adhesions; sections were greyish white, bulky, firm and airless. The gastrointestinal tract was normal. Severe ulcerative tracheobronchitis and left adrenal vein thrombosis were also noted. Light microscopic findings: The lungs showed diffuse interstitial fibrosis with prominent type II cell hyperplasia and focal squamous metaplasia in the small bronchioles. Some alveolar lining cells and a few other types of cells were enlarged and had a prominent eosinophilic intranuclear inclusion surrounded by a clear halo characteristic of cytomegalovirus (Fig. 1). Some alveolar spaces contained foamy eosinophilic material that Grocott's stain revealed to be the cyst forms of P. carinii. Cytomegalovirus inclusions were also found in the mediastinal lymph nodes and the adrenal glands but were absent in other organs, including the gastrointestinal tract. The left adrenal vein contained an organized thrombus, and the left adrenal showed foci of hemorrhagic infarction in the cortex. P. carinii was found only in the lungs. Electron microscopic findings: Trophozoites of P. carinii 1 to 2 .tm in diameter formed aggregated masses in some alveolar spaces (Fig. 2). Elongated pseudopodia were intermingled into a complicated network. The nucleus and cytoplasm of some of the trophozoites contained FIG. 3-Trophozoites containing small, round, electron-dense bodies (arrows) 48 to small, round, electron-dense bodies 80 nm in diameter. Complicated networks of pseudopodia evident in upper half of ranging in diameter from 48 to 80 field. (Uranyl acetate-lead citrate; X63 000.) 1099
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iratory disease was compatible with both P. carinji and cytomegalovirus pneumonia.6 Pathological studies confirmed the simultaneous presence of P. carinli and a virus of the herpes group in the lungs both before and after death. Though electron microscopy does not permit differentiation of the several viruses
in this group (herpes simplex virus, vaccinia-herpes zoster virus and cytomegalovirus), light microscopy does allow diagnosis of cytomegalovirus infection, as in this case. No underlying malignant disease was found in our patient, and he had not received immunosuppressive medication. However, his host defences,
FIG. 4-Three trophozoite-like bodies in cyst with defect in wall (arrow). (Uranyl acetate-lead citrate; X63 000.)
FIG. 5-Cytomegalovirus particles 76 to 84 nm in diameter in cytoplasm and nucleus of alveolar lining cells. Some intracytoplasmic particles are extruding through defect in cell membrane (arrow). (Uranyl acetate-lead citrate; X30 000.)
especially cellular immunity, may have been diminished secondary to malnutrition,7 which was suggested by the weight loss and the low serum level of albumin following 10 months of diarrhea. Hughes and associates,8 from their work with children and laboratory animals, suggested that protein-calorie malnutrition may be the most important host factor predisposing to P. carinji pneumonia. No cause for this patient's diarrhea was found before or after death. Generalized cytomegalovirus infection was evident; however, no cytomegalovirus inclusions were seen in the gastrointestinal tract. Trophozoite and cyst forms of P. carinii were found only in the lungs. Given the frequent concurrence of disease caused by P. carinji and cytomegalovirus,9 is there an interaction between these agents resulting in greater pathogenicity? Infec tion, as opposed to disease, due to P. carinji or cytomegalovirus is very common. The prevalence of antibodies to cytomegalovirus in adult populations ranges from 40% to 100%, depending on geographic region and socioeconomic factors.'0 Prevalence rates of 94% and 54% respectively have been reported for homosexual and heterosexual men attending the same venereal disease clinic.' Cytomegalovirus-induced immune dysfunction'2 4 may be responsible for an increase in susceptibility to opportunistic infections, and the high prevalence of cytomegalovirus infection might therefore explain the epidemic of opportunistic infection in homosexuals4 due to so-called acquired immune deficiency syndrome (AIDS).'6 Our patient, a Haitian immigrant, is also a member of a group at high risk in this epidem1617 ic. There is evidence of a more specific interaction between cytomegalovirus and P. carin ii. We observed small, round bodies 48 to 80 nm in diameter in some trophozoites (Fig. 3). These electron-dense particles were similar in size and appearance to the core of the virus particles seen in the alveolar lining cells (Fig. 5). They also closely resembled the round bodies, interpreted as being cytomegalovirus particles, observed within the trophozoites of P. carinii in another case of fatal pneumonia.
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There is good evidence for infection of other protozoa by viruses.'8 It is plausible that P. carinji might act as an intermediate host for cytomegalovirus and that this particular symbiotic relationship might explain our findings as well as the frequent concurrence of the infections by the two organisms. Although other explanations are possible,5"9 it seems worth while to conduct electron microscopic studies of lung tissue from additional patients with the two infections in an attempt to confirm our findings. We thank Mrs. Hassmig Minassian, BSc, RT for her technical and photographic help. Dr. Ernst is the recipient of a grant from the Institut de recherche en sant6 et s6curit6 au travail du Quebec. References
9. L. CLAIR RA: Descriptive epidemiology of interstitial pneumocystic pneumonia. An analysis of 107 cases from the United States, 1955-1967. Am Rev Respir Dis
1969; 99: 542-547 10. KRECH U: Complement-fixing antibodies against cytomegalovirus in different parts of the world. Bull WHO 1973; 49: 103106 11. DREW WL, MINTZ L, MINER RC, SANDS M, KETTERER B: Prevalence of cytomegalovirus infection in homosexual men. J Infect Dis 1981; 143: 188-192 12. RAND KH, POLLARD RB, MERIGAN TC: Increased pulmonary superinfections in cardiac-transplant patients undergoing primary cytomegalovirus infection. N Engi J Med 1978; 298: 95 1-953 13. RINALDO CR IR, CARNEY WP, RICHTER BS, BLACK PH, HIRSCH MS: Mecha-
1. WALZER PD, PERL DP, KROG5TAD DJ,
nisms of immunosuppression in cytome-
RAwsoN PG, SCHULTZ MG: Pneumocystis carinii pneumonia in the United States: epidemiologic, diagnostic, and clinical features. Ann Intern Med 1974; 80: 83-93
galoviral mononucleosis. J Infect Dis 1980; 141: 488-495
2. HAMPERL H: Pneumocystis infection and cytomegaly of the lungs in the newborn and adult. Am J Pathol 1956; 32: 1-13 3. RIFKIND D, STARZL TE, MARCHIORO IL, WADDELL WR, ROwLANDS DT JR,
HILL RB IR: Transplantation pneumonia. JAMA 1964; 189: 808-8 12
14. MASUR H, MIcHELIs MA, GREENE JB, ONORATO I, STOUWE RA, HOLZMAN RS, WORMSER G, BRETTMAN L, LANGE M, MURRAY HW, CUNNINGHAM-RUNDLE5 5: An outbreak of communityacquired Pneumocystis carinii pneumonia: initial manifestation of cellular immune dysfunction. N Engi J Med 1981; 305: 1431-1438
4. Kaposi's sarcoma and Pneumocystis pneumonia among homosexual men New York City and California. Morb Mortal Wkly Rep 1981; 30: 305-308
15. SEIGAL FP, LOPEZ C, HAMMER GS, BROWN AE, KORNFELD SI, GOLD I, HA55ETT J, HIR5CHMAN SZ, CUNNINGHAM-RUNDLES C, ADELE5BERG BR, PARNHAM DM, SIEGAL M, CUNNINGHAM-RUNDLES 5, ARMSTRONG D: Severe
5. WANG NS, HUANG SN, THURLBECK
mosexuals, manifested by chronic penanal ulcerative herpes simplex lesions.
WM: Combined Pneumocystis carinii
acquired immunodeficiency in male hoIbid: 1439-1444
and cytomegalovirus infection. Arch Pathol 1970; 90: 529-535 16. Update on acquired immune deficiency 6. ABDALLAH PS, MARK IB, MERIGAN TC: Diagnosis of cytomegalovirus pneumonia in compromised hosts. Am J Med 1976; 61: 326-332 7. SMYTHE PM, SCHONLAND M, BRERETON-STILES GG, CooVADIA HM, GRACE HI, LOENING WEK, MAFOYANE A, PARENT MA: Thymolymphatic deficiency and depression of cell-mediated immunity in protein-calorie malnutrition. Lancet 1971; 2: 939-943 8. HUGHES WT, PRICE RA, SISKO F, HAyRON WS, KAFATOS AG, SCHONLAND M, SMYTHE PM: Protein-calorie malnutrition: a host determinant for Pneumocystis carinii infection. Am J Dis Child 1974; 128: 44-52
syndrome (AIDS) - United States. Morb Mortal Wkly Rep 1982; 31: 507-514
17. Opportunistic infections and Kaposi's sarcoma among Haitians in the United States. Ibid: 353-361 18. SCHUSTER FL: Intranuclear virus-like bodies in the amoeboflagellate Naegleria
gruberi. J Protozool 1969; 16: 724-727 19. GOTTLIEB MS, SCHROFF R, SCHANKER HM, WEISMAN ID, FAN PT, WOLF RA,
SAXON A: Pneumocystis carinii pneumonia and mucosal candidiasis in previously healthy homosexual men: evidence of a new acquired cellular immunodeficiency.
NEnglJ Med 1981; 305: 1425-1431
