Apr 7, 2009 - infection presenting as atypical pneumonia (5), we adopted serological testing (6) and a nested polymerase chain reaction (PCR) assay to ...
Jpn. J. Infect. Dis., 67, 122-126, 2014
Short Communication
A Case Series of Possibly Recrudescent Orientia tsutsugamushi Infection Presenting as Pneumonia Jae-Hyoung Im1, Ji Hyeon Baek1, Jin-Soo Lee1, Moon-Hyun Chung1*, Sun Myoung Lee2, and Jae-Seung Kang3 1Department 3Department
of Internal Medicine, 2Translation Research Center, and of Microbiology, Inha University School of Medicine, Incheon, Korea (Received August 1, 2013. Accepted October 2, 2013)
SUMMARY: Orientia tsutsugamushi remains latent in humans after scrub typhus. Pneumonia occurs as a complication of scrub typhus in the late-phase disease. However, pneumonia may also occur as a presenting manifestation of O. tsutsugamushi infection. We reviewed the cases of 3 patients with atypical pneumonia who presented at our hospital and were later confirmed to have O. tsutsugamushi infection by serology, nested polymerase chain reaction (PCR), and cell culture. All patients were young adults with no history of scrub typhus, and none claimed to have recently been exposed to areas where scrub typhus is endemic. Two cases occurred in non-outbreak seasons. Furthermore, eschar was not observed. Pneumonia was documented within 4 days after fever onset. The immunoglobulin (Ig) G antibody titers against O. tsutsugamushi were higher than the IgM titers, although the serologic test results were less helpful in the diagnosis. Nested PCR and cell culture of blood specimens confirmed the diagnosis of O. tsutsugamushi infection. These findings suggest that pneumonia can occur as a result of recrudescence of latent O. tsutsugamushi infection. Scrub typhus is a mite-borne disease caused by Orientia tsutsugamushi. The bacterium, after its entry into the host, enters a chronic latent stage that is associated with certain conditions, such as early recrudescence (1), and the transmission of the bacterium through blood (2). No other clinical manifestations of chronic O. tsutsugamushi infection are known. Pneumonia usually occurs after the first week of illness in circumstances where appropriate antibiotic treatment is delayed (``secondary O. tsutsugamushi pneumonia'') (3,4). However, pneumonia may also occur as a presenting manifestation of O. tsutsugamushi infection, as described in our previous study published in 2008 (5). Since the 2008 report of a case of O. tsutsugamushi infection presenting as atypical pneumonia (5), we adopted serological testing (6) and a nested polymerase chain reaction (PCR) assay to amplify the gene encoding the 56-kDa type-specific antigen (TSA56) of O. tsutsugamushi (7) for patients with atypical pneumonia who visited the outpatient clinic of our hospital. If PCR analysis revealed positive results, the blood specimens were further evaluated by cell culture. Because pneumonia was primarily managed in the pulmonary division of our hospital, the number of patients evaluated in this manner was relatively small (approximately 12 patients per year). Among these, 2 patients were diagnosed with O. tsutsugamushi infection. On the basis of epidemiological and clinical features of these cases, we propose that pneumonia can occur as a result of recrudescent O.
tsutsugamushi infection (``recrudescent O. tsutsugamushi pneumonia''). Case 1: A 31-year-old woman presented at our hospital with a fever and reddish urine on April 7, 2009. The patient had a history of acute pyelonephritis, thyroid cancer, and persistent microscopic hematuria. She had delivered a baby 8 months earlier and had not participated in outdoor activities in the 4 weeks before fever onset. A urinalysis showed hematuria and pyuria. Therefore, a urine culture was ordered and cefixime was empirically prescribed for acute pyelonephritis. The fever persisted despite 2 days of antibiotic therapy; hence, she was admitted to our hospital on day 3 of her illness. Upon admission, her vital signs were as follows: body temperature, 38.39C; pulse rate, 88 beats/min; blood pressure, 110/70 mmHg; and respiration rate, 16 breaths/min. There was no evidence of rash, eschar, conjunctival injection, or lymphadenopathy. Laboratory tests revealed a hemoglobin level of 12.1 g/dL, leukocyte count of 8,300 cells/mL, platelet count of 278,000 platelets/mL, C-reactive protein (CRP) level of 47.5 mg/L, and an erythrocyte sedimentation rate (ESR) of 21 mm/h. The results of liver function tests were within normal ranges. A previously ordered urine culture revealed no pathogens. The patient developed a cough after admission. A chest radiograph showed mild bilateral reticular infiltration, and a computed tomography (CT) scan of the chest showed diffuse ground-glass opacities in both lungs and bilateral pleural effusion. Cefotaxime was administered for 3 days, but no clinically beneficial effects were observed. On day 6 of the illness, her body C and her cough became more temperature rose to 399 severe. A chest radiograph showed aggravated findings; therefore, doxycycline was substituted for cefotaxime. Afterward, the patient's clinical symptoms improved over 2 days and she became afebrile on day 8, at which
*Corresponding author: Mailing address: Department of Internal Medicine, Inha University Hospital, Shinheungdong, Jung-gu, Incheon 400-712, Republic of Korea. Tel: ＋82-32-890-2202, Fax: ＋82-32-882-6578, E-mail: mhchungid＠daum.net 122
Recrudescent O. tsutsugamushi Pneumonia
for IgG against the Boryong strain of O. tsutsugamushi were 1:40 and 1:160 on days 3 and 14, respectively. Nested PCR was performed on buffy coat specimens sampled on days 3 and 14, which detected the TSA56 gene of O. tsutsugamushi, as evidenced by the presence of a 483-bp band. Sequencing of the nested PCR product revealed the Boryong genotype (GenBank accession no. JX679715). A cell culture of an EDTAtreated whole blood specimen taken on day 3 revealed growth of O. tsutsugamushi 9 weeks later. The demographic and clinical features of the 2 cases of O. tsutsugamushi pneumonia in the present study and the previously reported case are shown in Table 2. The descriptions of these 3 cases imply that O. tsutsugamushi infection can present as community-acquired pneumonia, particularly atypical pneumonia. In case 1, the IgG titers were higher than the IgM titers, suggesting that the O. tsutsugamushi infection was a reinfection or recrudescence. Presumably, the patient acquired the O. tsutsugamushi infection when she was younger, and scrub typhus was not suspected at that time. Such seropositive persons, including children with no history of scrub typhus, are commonly encountered in areas where scrub typhus is endemic (8). In addition, all 3 patients resided in an urban area and had not engaged in any outdoor activities in the 4 weeks preceding illness. Two of the 3 patients developed infection during nonoutbreak seasons of scrub typhus in Korea (i.e., between January and September). In Korea, 96z of all scrub typhus cases reported to the Korea Centers for Disease Control and Prevention occur between October and November (9), and seasonal occurrence of such cases is closely related to the population density of chigger mites. Mite density peaks twice a year in Korea, with a major peak in autumn and a minor peak in spring. However, no chigger mites are captured during summer (10). These epidemiological features suggest that the present cases had little to no possibility of exposure to infected chigger mites. Furthermore, these 3 patients did not exhibit eschar, which suggested that recrudescence or reinfection (11) was more likely than primary infection. It is unlikely that physical examinations failed to identify eschar because this condition was repeatedly monitored during hospitalization. Respiratory acquisition of O. tsutsugamushi infection (``primary O. tsutsugamushi pneumonia'') may be one explanation for the absence of eschar, but infection by such means is unrealistic outside of the laboratory setting. The clinical manifestations of O. tsutsugamushi infection in a patient who acquired the infection, possibly thorugh the respiratory route in a laboratory setting, were typical of
time she was discharged from our hospital. At followup 7 days later in the outpatient clinic, she had neither fever nor cough, and a follow-up chest radiograph showed complete clearance of the pulmonary infiltrates. Laboratory tests were performed to identify the cause of pneumonia. A blood culture showed no growth of pathogens. Tests for immunoglobulin (Ig) G and IgM antibodies against Chlamydophila pneumoniae were negative, and a sputum culture tested negative for respiratory viruses. Real-time PCR of the sputum was negative for Mycobacterium tuberculosis. Urinary antigens of Streptococcus pneumoniae and Legionella pneumophila were not detected. Furthermore, tests for antimycoplasma antibodies were negative. Results from an immunofluorescence assay (IFA) showed that titers against the Boryong strain of O. tsutsugamushi were 1:80 for IgG and º1:40 for IgM. Nested PCR to detect the TSA56 gene of O. tsutsugamushi in blood specimens taken on days 3 and 6 revealed a compatible 483-bp band. A cell culture of an EDTA-treated blood specimen taken on day 6 revealed growth of O. tsutsugamushi 119 days after inoculation. Sequencing of the TSA56 gene from the cultured isolate was most similar to the Karp genotype (GenBank accession no. HQ660203). IFA tests were performed using representative strains of O. tsutsugamushi such as Karp (ATCC VR-150), Gilliam (ATCC VR-312), and Kato (Niigata strain) and the patient's isolate (Table 1). Case 2: A 37-year-old woman was referred to the outpatient clinic of our hopital on October 4, 2011 because of fever. She underwent a gastrointestinal evaluation because of abdominal pain, and an abdominal CT scan incidentally detected pneumonic infiltrates in the right lower lobe, although respiratory symptoms were absent. We retrospectively learned that the patient had developed fever on the day before the abdominal CT. A chest radiograph taken on day 3 of the patient's illness revealed a focal consolidation and reticular pneumonic infiltrates in the right lower lobe. The patient had not recently traveled to an area where scrub typhus is endemic and had no signs of rash, eschar, conjunctivitis, or lymphadenopathy. A blood test revealed the following: hemoglobin level, 12.8 g/dL; leukocyte count, 6,940 cells/mL; platelet count, 240,000 platelets/mL; CRP, 42.5 mg/L; and ESR, 21 mm/h. Tests for antibodies against mycoplasma and C. pneumoniae were negative. Levofloxacin (700 mg/day) was prescribed for community-acquired pneumonia, and the fever abated 3 days later. A dry cough developed on day 3 and lasted for 2 days. A chest radiograph taken on day 10 of the illness revealed no pneumonic infiltrate. Antibody titers
Table 1. Immunofluorescent antibody titers of case 1 against representative strains of Orientia tsutsugamushi Strain
Boryong Karp (ATCC VR-150) Karp (clinical isolate from case 1) Kato (Niigata strain) Gilliam (ATCC VR-312)
Serum on day 6
Serum 4 months later
IgG IgM (reciprocal titers)
IgG IgM (reciprocal titers)
80 160 640 40 80
123
º40 80 160 º40 º40
160 160 1,280 80 80
º40 º40 40 º40 º40
Table 2. Demographic, epidemiological, and clinical features of 3 patients with recrudescent Orientia tsutsugamushi pneumonia Present case Case 1 Sex/age (yr) F/31 Occurrence (month, year) April 2009 Residence Urban (Incheon) Preceding event (day before fever) None Initial symptom Fever Day of detecting pneumonia by radiography Day 3 Location of pneumonia Bilateral lower Eschar Absent Rash Absent Lymphadenopathy Absent 8,300 Leukocyte count on admission (/mL) 278,000 Platelet count on admission (/mL) Antibodies to the Boryong strain of O. tsutsugamushi Acute IgM º1:40 IgG 1:80 Convalescent IgM º1:40 IgG 1:160 (4 months later) Blood nested PCR Positive Cell culture Positive Genotype Karp 1): 2):
Previous case1) Case 2
F/37 October 2011 Urban (Incheon) None Fever Day 2 Right lower Absent Absent Absent 6,940 240,000
M/16 July 2007 Urban (Incheon) Bone fracture (8) Fever, headache Day 2 Left lower Absent Absent Present 7,100 72,000
IgG 1:40
º1:202)
IgG 1:160
1:802)
(on day 14) Positive Positive Boryong
(on day 22) Positive Positive Not done
Reference no. 5. Measured by polyvalent antibody.
of scrub typhus (14–17), only a limited number (18–20), primarily case reports (21–22), have mentioned the day when pneumonia was first identified. A previous retrospective study reported that radiological abnormalities frequently occurred in scrub typhus cases 1–3 days after fever onset; however, because no detailed information was provided, comparisons with our cases were not possible (18). Among these case reports, 2 patients developed pneumonia in the early phase of scrub typhus. One case (case 1) described by Lee et al. (21) showed bilateral pulmonary infiltrates on day 3 of illness. Because eschar was present and the IgG titers were higher than the IgM titers, reinfection was suggested as the cause of pneumonia, similar to the clinical manifestation of recrudescent O. tsutsugamushi pneumonia. The patient reported by Yamamoto et al. (22) had bilateral pneumonitis on day 4, the absence of eschar, and higher IgG titers than IgM titers. This case likely represented reactivation of a dormant O. tsutsugamushi infection. The pathogenesis of recrudescent O. tsutsugamushi pneumonia is intriguing. O. tsutsugamushi is found in various cells, including endothelial cells, macrophages, cardiac myocytes, and blood mononuclear cells, during symptomatic O. tsutsugamushi infection in humans (23–25). Among these cells, alveolar macrophages are located only in the lungs and, therefore, are considered to play a primary role in recrudescent O. tsutsugamushi pneumonia. Macrophages that act as reservoir cells have a well-known role in several chronic bacterial infections, including tuberculosis (26). However, no cell type that acts as the reservoir in chronic O. tsutsugamushi infection has been identified yet; therefore, further studies focusing on the identification of O. tsutsugamushi in macrophages are warranted. In addition, an immune
scrub typhus (12). Considering all of these findings, each of the present cases of O. tsutsugamushi pneumonia most likely resulted from recrudescence of a latent infection. Given that none of the patients had a history of scrub typhus, it is crucial that further studies be conducted to investigate when and how patients with this illness may have acquired O. tsutsugamushi infections when younger. The overall features of recrudescent O. tsutsugamushi pneumonia in our cases were similar to those of type 2 antibody responders, i.e., reinfection type, as described by Bourgeois et al. (13). Patients with this type of infection show a lower incidence of eschar, rash, and conjunctivitis, a higher incidence of generalized lymphadenopathy, quicker response to antibiotics, and a lower recurrence rate than those with primary infections. Eschar, rash, and conjunctivitis were not observed in any of the present cases, and the response to antibiotics was rapid in each. With regard to pneumonia, radiographic abnormalities were similar to those of previously reported cases of O. tsutsugamushi pneumonia (14–17), i.e., ground-glass or reticular opacity and the occurrence of pneumonic infiltrates predominantly in the lower lobes. In contrast to these similarities, the time interval between the onset of fever and radiographic identification of pneumonia differed. Previous studies have reported that secondary O. tsutsugamushi pneumonia generally occurs 2–3 weeks after the fever onset in American servicemen with no previous exposure to O. tsutsugamushi (3,4), whereas pneumonia is detected within 1–3 days after fever onset in patients with recrudescent O. tsutsugamushi pneumonia, as shown in our cases. Although many studies have been performed to investigate the pulmonary manifestations 124
Recrudescent O. tsutsugamushi Pneumonia
reaction may be involved in the pathogenesis of recrudescent O. tsutsugamushi pneumonia. In biopsies and autopsies of patients with O. tsutsugamushi pneumonia, pathological examinations of lung tissues have revealed nonspecific interstitial inflammation and no vasculitis (23,25,27) or mild perivasculitis (28), suggesting elicitation of an immune response (25,27). In patients with recrudescent or reinfected O. tsutsugamushi infections, immunity to O. tsutsugamushi is present at onset; thus, tissue injury by the immune reaction may begin immediately after exposure to the triggering events or chigger mites. This contrasts with primary infection, in which such events begin beyond 7 days of infection. In the cases included in the present study, antibody responses to the O. tsutsugamushi reference strains were poor. Treatment during the early phase of illness resulted in poor antibody responses (29) and, possibly, was the primary cause of low antibody titers in one of the present cases (case 2) and in our previously reported case. However, in case 1, the duration of illness before initiation of appropriate antibiotic therapy was sufficient for antibody development. In addition, it is well known that antibody titers differ depending on the O. tsutsugamushi phenotype used as the antigen. In case 1, although the duration was sufficient to produce antibodies and the reference Karp strain was employed as the antigen, the antibody titers to the reference strain were low. Conversely, when the actual patient isolate was used as the antigen, antibody titers were sufficiently high to permit a diagnosis of scrub typhus, which suggests that antigenic components absent in the reference Karp strain were involved in the determination of antigenicity. This phenomenon may be comparable to the finding that Weil–Felix antibody titers were lower in patients without eschar than in those with eschar (30). While we are unsure why the antibody response to the reference strain of O. tsutsugamushi was not sufficiently high, the possibility of poor antibody formation in patients with recrudescent O. tsutsugamushi pneumonia has significant implications in the diagnosis of this illness. In our patients, the clinical manifestations of recrudescent O. tsutsugamushi pneumonia were nonspecific (e.g., fever and pulmonary infiltrates) and not accompanied by findings characteristic of scrub typhus such as eschar or rash. Thus, the detection of a Æ4-fold increase in antibody titers is an important diagnostic characteristic for most clinicians practicing in scrub typhus-endemic areas. However, as we have shown, antibody titers, even during the convalescent phase of the illness, are relatively low; therefore, molecular diagnostic methods or shell vial culture may be useful for the early diagnosis of recrudescent O. tsutsugamushi pneumonia. In conclusion, we propose that recrudescent O. tsutsugamushi infection is a potential cause of atypical pneumonia. This illness should be considered in patients with atypical pneumonia in endemic areas of scrub typhus, in the absence of eschar or epidemiological risk factors for exposure to mites, and even in those without a history of scrub typhus. Measurements of both IgG and IgM antibodies are necessary to differentiate between recrudescence or reinfection from primary infection.
Acknowledgments This work was supported by an Inha University Research Grant.
Conflict of interest None to declare. REFERENCES 1. Chung, M.H., Lee, J.S., Baek, J.H., et al. (2012): Persistence of Orientia tsutsugamushi in humans. J. Korean Med. Sci., 27, 231–235. 2. Hayashi, H. and Watanabe, M. (1948): On the possibility of appearance of rickettsiae in the circulating blood after the recovery of rickettsiosis. Kitasato Arch. Exp. Med., 21, 135–141. 3. Sayen, J.J., Pond, H.S., Forrester, J.S., et al. (1946): Scrub typhus in Assam and Burma. Medicine, 25, 155–214. 4. Berman, S.J. and Kundin, W.D. (1973): Scrub typhus in South Vietnam. A study of 87 cases. Ann. Intern. Med., 79, 26–30. 5. Park, S.D., Chung, M.H., Lee, H.M., et al. (2008): A case of scrub typhus in summer presenting as atypical pneumonia. Infect. Chemother., 40, 241–245 (in Korean). 6. Robinson, D.M., Brown, G., Gan, E., et al. (1976): Adaptation of a microimmunofluorescence test to the study of human Rickettsia tsutsugamushi antibody. Am. J. Trop. Med. Hyg., 25, 900–905. 7. Furuya, Y., Yoshida, Y., Katayama, T., et al. (1993): Serotypespecific amplification of Rickettsia tsutsugamushi DNA by nested polymerase chain reaction. J. Clin. Microbiol., 31, 1637–1640. 8. Tamiya, T. (1962): Recent Advances in Studies of Tutsugamushi Disease in Japan. Medical Culture Inc., Tokyo. 9. Kweon, S.S., Choi, J.S., Lim, H.S., et al. (2009): Rapid increase of scrub typhus, South Korea, 2001–2006. Emerg. Infect. Dis., 15, 1127–1129. 10. Lee, S.H., Lee, Y.S., Lee, I.Y., et al. (2012): Monthly occurrence of vectors and reservoir rodents of scrub typhus in an endemic area of Jeollanam-do, Korea. Korean J. Parasitol., 50, 327–331. 11. Smadel, J.E., Ley, H.L., Jr., Diercks, F.H., et al. (1952): Immunization against scrub typhus: duration of immunity in volunteers following combined living vaccine and chemoprophylaxis. Am. J. Trop. Med. Hyg., 1, 87–99. 12. Oh, M., Kim, N., Huh, M., et al. (2001): Scrub typhus pneumonitis acquired through the respiratory tract in a laboratory worker. Infection, 29, 54–56. 13. Bourgeois, A.L., Olson, J.G., Fang, R.C., et al. (1982): Humoral and cellular responses in scrub typhus patients reflecting primary infection and reinfection with Rickettsia tsutsugamushi. Am. J. Trop. Med. Hyg., 31, 532–540. 14. Song, S.W., Kim, K.T., Ku, Y.M., et al. (2004): Clinical role of interstitial pneumonia in patients with scrub typhus: a possible marker of disease severity. J. Korean Med. Sci., 19, 668–673. 15. Choi, Y.H., Kim, S.J., Lee, J.Y., et al. (2000): Scrub typhus: radiological and clinical findings. Clin. Radiol., 55, 140–144. 16. Charoensak, A., Chawalparit, O., Suttinont, C., et al. (2006): Scrub typhus: chest radiographic and clinical findings in 130 Thai patients. J. Med. Assoc. Thai., 89, 600–607. 17. Jeong, Y.J., Kim, S., Wook, Y.D., et al. (2007): Scrub typhus: clinical, pathologic, and imaging findings. Radiographics, 27, 161–172. 18. Chen, H.C., Chang, H.C., Chang, Y.C., et al. (2012): Chest radiographic presentation in patients with scrub typhus. Trans. R. Soc. Trop. Med. Hyg., 106, 48–53. 19. Wang, C.C., Liu, S.F., Liu, J.W., et al. (2007): Acute respiratory distress syndrome in scrub typhus. Am. J. Trop. Med. Hyg., 76, 1148–1152. 20. Tsay, R.W. and Chang, F.Y. (2002): Acute respiratory distress syndrome in scrub typhus. Q. J. Med., 95, 126–128. 21. Lee, W.S., Wang, F.D., Wang, L.S., et al. (1995): Scrub typhus complicating acute respiratory distress syndrome: a report of two cases. China Med. J., 56, 205–210. 22. Yamamoto, Y., Kuroki, S. and Kajii, E. (2011): A case report of tsutsugamushi disease mimicking disseminated Bartonella infection. Jichi Med. Univ. J., 34, 103–108. 23. Moron, C.G., Popov, V.L., Feng, H.M., et al. (2001): Identification of the target cells of Orientia tsutsugamushi in human cases of scrub typhus. Mod. Pathol., 14, 752–759. 24. Walsh, D.S., Myint, K.S., Kantipong, P., et al. (2001): Orientia tsutsugamushi in peripheral white blood cells of patients with acute scrub typhus. Am. J. Trop. Med. Hyg., 65, 899–901.
125
25. Hsu, Y.H. and Chen, H.I. (2008): Pulmonary pathology in patients associated with scrub typhus. Pathology, 40, 268–271. 26. Peyron, P., Vaubourgeix, J., Poquet, Y., et al. (2008): Foamy macrophages from tuberculous patients' granulomas constitute a nutrient-rich reservoir for M. tuberculosis persistence. PLoS Pathog., 4, e1000204. 27. Park, J.S., Jee, Y.K., Lee, K.Y., et al. (2000): Acute respiratory distress syndrome associated with scrub typhus: diffuse alveolar damage without pulmonary vasculitis. J. Korean Med. Sci., 15,
343–345. 28. Levine, H.D. (1946): Pathologic study of thirty-one cases of scrub typhus fever with especial reference to the cardiovascular system. Am. Heart J., 31, 314–328. 29. Smadel, J.E. (1954): Influence of antibiotics on immunologic responses in scrub typhus. Am. J. Med., 17, 246–258. 30. Machella, T.E. and Forrester, J.S. (1945): Mite or scrub typhus: a clinical and laboratory study of 64 cases. Am. J. Med. Sci., 38, 38–61.
126
