Chlamydia pneumoniae, Strain TWAR, Infection in Patients with Chronic Obstructive Pulmonary Disease1-3
CHRISTOPHER D. BEATY, J. THOMAS GRAYSTON, SAN·PIN WANG, CHO·CHOU KUO, CATHERINE S. RETO, and THOMAS R. MARTIN
TWAR is a recently described bacterium of the genus Chlamydia that was first isolated in 1965 from the conjunctiva of a Taiwanese child. The organism was first assumed to be C trachomatis until growth in cell culture suggested that it was C. psittaci (1). Recently, however, on the basis of studies of ultrastructure and DNA homology, it has been designated a new chlamydia species named Chlamdyia pneumoniae (2). So far, only one strain or serovar, the TWAR strain, has been found. Unlike C trachomatis, TWAR does not appear to be a sexually transmitted disease (3) or a significant cause of conjunctivitis. Nevertheless, prevalence studies have shown TWAR antibody in 40 to 60070 of adults, with an increasing prevalence into old age (4). The first evidence of TWAR as a respiratory pathogen came from serologic studies of patients with radiographically demonstrated pneumonitis during an unusual epidemic in northern Finland (5). This was followed by isolation of the organism from patients with acute respiratory disease (1). Since then the importance of TWAR as a cause of both isolated cases and epidemics of pneumonia has been confirmed (6). Although the role of TWAR as a cause of pneumonia has been established, the potential importance of TWAR infection in patients with chronic lung disease has not been defined. In general, the causal relationship between infection of the respiratory tract and acute exacerbations of COPD has been difficult to prove (7). Antibiotic intervention studies have provided inferential evidence of this link (8), but studies to the contrary also exist (9). Culture evidence of this association has been difficult to interpret since the likely pathogens also colonize the respiratory tract of patients with COPD. In contrast, TWAR is not known to colonize the respiratory tract, though no studies have specifically addressed this issue in patients with COPD. The availability of excellent serologic tests and isolation techniques specific for C pneumoniae strain TWAR has provided us with the opportunity to assess the role of TWAR infection in patients with COPD. Three patient populations were studied prospectively at the Seattle Veterans Administration Medical Center. Group 1: patients admitted to the hospital with acute exacerbations of COPD; Group 2: a randomly selected group of patients with stable COPD who were seen in the pulmonary medicine clinic; Group 3: age- and sex-matched patients without COPD. Group 1. We evaluated all patients admitted to 1408
SUMMARY TWAR, the only known serovar of ChlamydIa pneumonlae, Is a newly described bacterium that hss been identified as a cause of both epidemics and endemic CBsesof pneumonia. The role of TWARInfection In patients with chronic obstructive pUlmonery dlseese (COPO)Is not known. We conducted a prospective study to establish Whether TWAR Infection Is a common ceuse of ecute exacerbstlons of COPO. We studied two groups of petlents: 44 patients admitted to the hospital with acute exacerbations of COPO, and 65 stable clinic patients with COPO. we found that evidence of acute TWAR Infection was Infrequent In patients with exacerbstlons (5%). In contrast, the majority of patients from both groups had serologic evidence of previous TWAR Infection (77%). This was not significantly greater than the prevalence found In a small group of patients of similar age and aex without lung dlaease from Ihe seme Institution (73%). TWAR was not Isoleted from the oropharyngealspeclmena obtained from W sublects, suggesting that It does not colonize the respiratory tract of patients with COPO.This study shows that at the time of low Incidence In the community, acute TWARInfection Is uncommon In patients with acute exacerbations of COPO.The majority of patients with COPOhave, however, been Infected with TWAR In the past. The clinical manifestations of these Infections are not known and should be the focus of further studies. AM REV RESPIR DIS 1991; 144:1408-1410
the Seattle Veterans Administration Medical Center from February 1987 to February 1988 with exacerbations of COPD. Admitting records were reviewed daily to identify patients who had been admitted in the previous 24 h with respiratory complaints. The charts of all such patients were evaluated for evidence that the patient had COPD. An acute exacerbation of COPD was defined as the new onset of dyspnea or a worsening of chronic dyspnea in a patient with known COPD and without an alternate explanation for their symptoms. Accordingly, patients with COPD were excluded from the study if they had clinical findings of congestive heart failure or dyspnea related to other causes (i.e., metabolic acidosis, severe anemia, neuromuscular diseases). To maximize the likelihood of identifying acute C. pneumoniae infection, we also excluded patients if they had received antibiotics in the 2 wk prior to enrollment or had an acute respiratory illness in the 2 months prior to enrollment. We screened 186 patients and enrolled 44. The reasons for exclusion were: recent respiratory illness (48010), congestive heart failure (10010), recent antibiotic therapy (3010). Only 5010 refused to participate. Forty-one (35010 of those excluded) were excluded either because they did not have COPD or because, despite the diagnosis on the admitting records, they had COPD but were not admitted with a change in their respiratory symptoms. Group 2: A random sample of pulmonary clinic patients was evaluated between December 1987and March 1988. Every third chart, by hospital number, was reviewed for evidence of COPD. All patients with this diagnosis were considered for participation in the study. The exclusion criteria were the same as for the patients in Group 1. We screened 116patients and enrolled 65. Patients were excluded because ofrecent respiratory illness (63010) and recent antibiotic therapy (6010). Nine (18010) of the patients who were randomly selected failed to keep their clinic appointment. Seven patients (14010) refused to participate.
Group 3: Between April and July 1988 we screened patients in the Seattle Veterans Administration Medical Center Urology Clinic who were between 45 and 70 yr of age for evidence of airflow obstruction. We performed simple spirometryon 31 patients using a BREON spirometer to ensure that they did not have occult airflow obstruction. Patients were excluded if they had a FEV 1 less than 80010 predicted, a FVC less than 80010 predicted or FEV./FVC less than 0.75. Additional exclusion criteria were the same as for Groups 1 and 2. We identified 24 patients without airflow obstruction who were similar in age and of the same sex as the patients with COPD and who were willing to participate in the study. Patients in all groups were interviewed by the study coordinator at the time of entry into the study. All patients answered the same predetermined questions. Baseline pulmonary function tests were available for the majority of Group 1 and 2 patients. Pertinent laboratory values and chest radiographs were obtained on all Group I patients. Radiographs were interpreted independently by two of the investigators.
(Received in original form January 28, 1991 and in revised form May 30. 1991) • From the Medical Service, Seattle Veterans Administration Medical Center, and the Departments of Medicine, Epidemiology, and Pathobiology, University of Washington, Seattle, Washington. • Supported in part by Public Health Service Research Grant AI-21885 from the National Institutes of Health. 3 Correspondence and requests for reprints should be addressed to Christopher D. Beaty, M.D., Department of Medicine, Division of Pulmonary and Critical Care Medicine RM-12, University of Washington, Seattle, WA 98195.
BRIEF COMMUNICATION
1409 TABLE 1
CLINICAL CHARACTERISTICS OF THE STUDY POPULATION
Age, mean ± SD Sex, M:F Home oxygen use, n (%) Chronic steroid use, n (%) Previously hospitalized for COPD, n (%) History of chronic bronchitis, n (%) Findings on presentation Temperature> 37.7° C, n (%) WBC > 10 K, n (%) Lung infiltrate
Group 1 (n = 41)*
Group 2
Group 3
(n = 65)
(n = 24)
67.9 ± 5.7 39:2 11 (27) 11 (27)
65.5 ± 7.5 63:2 7 (11) 16 (25)
62.7 ± 6.0 21:3
28 (68)
36 (55)
11 (27)
12 (18)
3 (7) 26 (63)
o
• Data not available for three subjects.
TABLE 2 BASELINE PULMONARY FUNCTION TESTS Group 1 (n
FEV" ml FEV,. %t FVC, ml FVC,% FEV,/FVC
1.03 45.68 2.45 58.69 40.6
Group 2
= 25) ± ± ± ± ±
(n
0.52:1: 32.39 0.69 18.02 16.4
1.42 53.29 2.88 64.5 47.4
Group 3'
= 53) ± ± ± ± ±
(n
0.73:1: 34.83 0.93 19.53 14.0
3.02 96.65 3.80 85.79 79.4
= 24) ± 0.43 ± 11.9 ± 0.67
± 10.79 ± 6.6
• All Group 3 values were significantly greater than the values in either Group 1 or Group 2. t Denotes percentage predicted based on height, age, and sex. Denotes statistically significant difference between Group 1 and Group 2.
*
TABLE 3 ANTIBODY AGAINST TWAR IN SUBJECTS WITH ACUTE EXACERBATION OF COPD (GROUP 1), WITH STABLE COPD (GROUP 2), OR WITHOUT COPD (GROUP 3)
(n
Group 1 (27)'
= 44)
(n
Group 2 (44)*
Group 3 = 24)
= 65)
(n
Antibody
(n)
(%)
(n)
(%)
(n)
(%)
Acute Preexistingt
2 43
5 81
0 50
rr
2 16
8 73
• Number of patients with paired serum specimens. all others single serum specimens. Percent preexisting antibody is determined with persons with acute antibody removed from denominator.
t
Efforts to obtain paired sera at 2- to 3-month intervals were made for all subjects in Groups 1 and 2. Subjects in Group 3 had a single serum sample obtained at the time of enrollment. All blood was tested for TWAR-specific IgG and IgM antibody using a microimmunofluorescence (micro-IF) test (1, 10), Current or recent TWAR infection was defined as a fourfold rise in antibody titer in either the IgM or IgG serum fraction, a titer of > 1:16 in the IgM serum fraction, or ;;. 1:512in the IgG fraction. Past TWAR infection was defined by an IgG titer of 1:16 to 1:256. Throat swab specimens suitable for culture were obtained from 32 Group I patients and all Group 2 patients. They were placed in Chlamydia transport media for culture and frozen at -70· C within 30 min of the time they were obtained. Isolation was performed using HeLa 229 cells (11).
The clinical characteristics of the subjects in each group are shown in table 1. Most of the subjects were men with an overall male to female ratio of 25:1. As expected, subjects were
in the older age groups with mean ages of 63 to 68 yr. Oxygen use, steroid use, smoking history, presence of chronic bronchitis, and number of hospital admissions in the previous 2 yr were similar in Groups 1 and 2. Pertinent clinical data were available for all but three Group 1 patients. Feverwas uncommon, but two thirds of the patients had elevated white blood cell counts. No patient had a new chest radiographic infiltrate. The results of baseline pulmonary function tests for patients in each of the three groups are shown in table 2. Baseline pulmonary function tests were available for 25 Group I patients (66070),53 Group 2 patients (81070), and all Group 3 patients. Patients in Groups I and 2 had severe airflow obstruction, with mean FEY, values of 1.03 and 1.42 Lis, respectively. The absolute values for FEY, were significantly lower in Group 1 than in Group 2; however, the difference was not sig-
nificant when expressed as a percentage of predicted based on height, weight, age, and sex. The patients in Group 3 had normal pulmonary function tests, consistent with the selection criteria. Paired serum samples were obtained in 27 Group 1 and 44 Group 2 patients. The remainder had one sample drawn at the time they wereenrolled. The mean interval between acute and convalescent samples was 12.6 (± 2.7) wk for those in Group 1 and 18.7 (± 8.1) wk for those in Group 2. The TWAR microimmunofluorescence serologic results are shown in table 3. Antibody suggesting recent infection was found in two Group 1 patients and in two Group 3 patients. In each group one had IgM antibody and one had high titer IgG antibody (~ 1:512). Preexisting antibody (lgG 1:16 to 1:256) was found in the majority of subjects and was equally distributed (73-81 0J0) through the three groups. Neither of the Group 1 patients with acute TWAR antibody had fever, leukocytosis, or a radiographic infiltrate during their hospitalization. Neither patient in Group 3 with serologicevidence of TWARinfection recalled any recent illness. Culture of throat swab specimens was successfully carried out on 30 of the hospitalized patients, including the two with acute TWAR antibody, and all were negative for C pneumoniae. Cultures wereobtained from 59 of the clinic patients, and the results were negative in all of them. When the clinical characteristics of all patients with COPD without preexisting TWAR antibody were compared, there wereno differences in their use of oxygen, steroids, or cigarettes. Pulmonary functions were similar in those with and without antibody as was the prevalence of chronic bronchitis and history of prior hospitalizations for exacerbations of COPD.
**** The primary goal of this study was to determine whether TWAR is a common cause of exacerbations of airflow obstruction in adult patients with CO PD. The selection criteria resulted in a narrowly defined group of patients in whom exacerbations of airflow obstruction were due to acute bronchitis without an obvious bacterial pathogen in the sputum. For comparison, a group of patients with similar degrees of airflow obstruction who were clinically stable and a group of patients who are free of lung disease as detected by questionnaire and screening spirometry were studied. We found that TWAR was an uncommon pathogen in this group of patients evaluated during 1987 and 1988.Only two of 44 patients with exacerbations had serologic evidence of acute TWAR infection, but the organism was not isolated from either patient. These findings indicate that, during the period of study, acute TWAR infection was not a common cause of exacerbations of COPD.
BRIEF COMMUNICATION
1410
1\vo methods of TWAR infection have been postulated, person-to-person spread of respiratory secretions and endogenous reinfection from dormant organisms in the respiratory tract (12). 1\vo factors may have reduced our chances of detecting person-to-person transmission of TWAR. First, from other investigations we learned that at the time of this study there was a low incidence of acute TWAR infection in the Seattle area. TWAR infections are periodic, with several years of higher incidence followed by years of low incidence (6). It is possible that more cases of acute TWAR might have been detected during another period in Seattle. Second, we excluded patients with recent respiratory infections and those who had been using antibiotics. Weexcluded patients with recent antibiotic therapy in order to avoid masking the TWAR culture results. These exclusion criteria could have eliminated some patients with acute TWAR infections from our study population. TWAR respiratory tract infection often has a subacute or biphasic onset, with lower respiratory tract involvement beginning later in the course of the disease. Some ofthe patients excluded for prior respiratory infection might have had TWAR infection associated with their hospitalization. This study provides some evidence against a significant role for relapse TWAR infection in COPD exacerbations. Such infections would not be influenced by the low community incidence of TWAR infection and should therefore be more prevalent in a population such as ours where the majority of patients have serologic evidence of previous infection. The low prevalence of acute TWAR infection in this study argues against this mechanism of infection. Similarly, our failure to isolate the organism from the oropharynx of these patients with COPD argues against (but does not disprove) the presence of latent TWAR respiratory tract infection or colonization. The finding of TWAR antibody indicating previous infection in 770/0 of patients with
COPD is the highest prevalence that we have found. The group of 24 patients without chronic lung disease who were tested had a prevalence of preexisting TWAR antibody (73%) similar to that of the patients with COPD. Two of these urology clinic patients had antibodies suggesting current or recent TWAR infection. There is no explanation for this surprising finding, and it raises a question about how good a comparison group these patients are. The prevalences in all three groups were much higher than the 53% prevalence observed in age-matched patients admitted with pneumonia to the same institution during 1980 and 1981 (12). Similarly, when patients in several other earlier Seattle area acute respiratory disease studies (4) were age- and sex-matched with our patients with COPD, a significantly lower antibody prevalence was found (57%), but when similar matching was done with patients from a Seattle area coronary artery disease study (13), the rate found (67%), although lower, was not a statistically significant difference (chisquare for differences in proportions using an average weighted by sample size, with age adjusted to the patients with COPD). These studies were carried out at different times, and the periodicity of TWAR infection may cause time-related differences in antibody prevalence. We cannot say that patients with COPD have a higher prevalence of preexisting TWAR antibody, but we can confidently say that most of our patients with COPD have been infected with TWAR in the past. The clinical manifestations of these infections remain to be defined leaving the possibility that TWAR could be a cause of significant morbidity in this population of patients with compromised pulmonary function.
References 1. Grayston JT, Kuo CC, Wang SP, Altman J. A new Chlamydia psittaci strain, TWAR, isolated in acute respiratory tract infections. N Engl J Med
1986; 315:161-8. 2. Grayston JT, Kuo CC, Campbell LA, Wang SP. Chlamydia pneumoniae sp. nov. for Chlamydia sp. strain TWAR. Int J Syst Bacteriol1989; 39:88-90. 3. Li DK, Daling JR, Wang SP, Grayston JT. Evidencethat Chlamydiapneumoniae, strain TWAR, is not sexually transmitted. J Infect Dis 1989; 160:328-31. 4. Wang SP, Grayston JT. Population prevalence antibody to Chlamydia pneumoniae, strain TWAR. In: Bowie WR, Caldwell HD, Jones RP, et al., eds. Chlarnydial infections. Cambridge: Cambridge University Press. 1990; 402-5. 5. Saikku P, Wang SP, Kleemola M, Brander E, Rusanen E, Grayston JT. An epidemicof mild pneumonia due to an unusual strain of Chalmydia psittaci. J Infect Dis 1985; 151:832-9. 6. Grayston JT, Campbell LA, Kuo CC, et al. A new respiratory tract pathogen: Chlamydia pneumoniae, strain TWAR. J Infect Dis 1990; 161:618-25. 7. Tager I, Speizer FE. Role of infection in chronic bronchitis. N Eng! J Med 1975; 292:563-71. 8. Anthonisen NR, Manfreda J, Warren CPW, Hershfield ES, Harding GKM, Nelson NK. Antibiotic therapy in exacerbations of chronic obstructive pulmonary disease. Ann Intern Med 1987; 106:196-204. 9. Nicotra MB, Rivera M, AweRJ. Antibiotic therapy of acute exacerbations of chronic bronchitis: a controlled study using tetracycline. Ann Intern Med 1982; 97:18-21. 10. Wang SP, Grayston JT. Immunologic relationship between genital TRIC, lymphogranuloma venereum, and related organisms in a new microtiter indirect immunofluorescence test. Am J Ophthalmol 1970; 70:367-74. 11. Kuo CC, Grayston JT. Factors affecting viability and growth in HeLa 229 cells of Chlamydia sp, strain TWAR. J Clin Microbiol1988; 26:812-15. 12. Grayston JT, Diwan VK, Cooney M, Wang SP. Community- and hospital-acquired pneumonia associated with Chlamydia TWAR infection demonstrated serologically. Arch Intern Moo 1989; 149:169-73. 13. Thorn DH, Wang SP, Stewart DK, Grayston JT. Chlamydia pneumoniaestrain TWAR antibody and angiographically demonstrated coronary artery disease. In: Bowie WR, Caldwell HD, Jones RP, et al. eds. Chlamydial infections. Cambridge: Cambridge University Press, 1990; 453-6.
CHRISTOPHER D. BEATY, J. THOMAS GRAYSTON, SAN·PIN WANG, CHO·CHOU KUO, CATHERINE S. RETO, and THOMAS R. MARTIN
TWAR is a recently described bacterium of the genus Chlamydia that was first isolated in 1965 from the conjunctiva of a Taiwanese child. The organism was first assumed to be C trachomatis until growth in cell culture suggested that it was C. psittaci (1). Recently, however, on the basis of studies of ultrastructure and DNA homology, it has been designated a new chlamydia species named Chlamdyia pneumoniae (2). So far, only one strain or serovar, the TWAR strain, has been found. Unlike C trachomatis, TWAR does not appear to be a sexually transmitted disease (3) or a significant cause of conjunctivitis. Nevertheless, prevalence studies have shown TWAR antibody in 40 to 60070 of adults, with an increasing prevalence into old age (4). The first evidence of TWAR as a respiratory pathogen came from serologic studies of patients with radiographically demonstrated pneumonitis during an unusual epidemic in northern Finland (5). This was followed by isolation of the organism from patients with acute respiratory disease (1). Since then the importance of TWAR as a cause of both isolated cases and epidemics of pneumonia has been confirmed (6). Although the role of TWAR as a cause of pneumonia has been established, the potential importance of TWAR infection in patients with chronic lung disease has not been defined. In general, the causal relationship between infection of the respiratory tract and acute exacerbations of COPD has been difficult to prove (7). Antibiotic intervention studies have provided inferential evidence of this link (8), but studies to the contrary also exist (9). Culture evidence of this association has been difficult to interpret since the likely pathogens also colonize the respiratory tract of patients with COPD. In contrast, TWAR is not known to colonize the respiratory tract, though no studies have specifically addressed this issue in patients with COPD. The availability of excellent serologic tests and isolation techniques specific for C pneumoniae strain TWAR has provided us with the opportunity to assess the role of TWAR infection in patients with COPD. Three patient populations were studied prospectively at the Seattle Veterans Administration Medical Center. Group 1: patients admitted to the hospital with acute exacerbations of COPD; Group 2: a randomly selected group of patients with stable COPD who were seen in the pulmonary medicine clinic; Group 3: age- and sex-matched patients without COPD. Group 1. We evaluated all patients admitted to 1408
SUMMARY TWAR, the only known serovar of ChlamydIa pneumonlae, Is a newly described bacterium that hss been identified as a cause of both epidemics and endemic CBsesof pneumonia. The role of TWARInfection In patients with chronic obstructive pUlmonery dlseese (COPO)Is not known. We conducted a prospective study to establish Whether TWAR Infection Is a common ceuse of ecute exacerbstlons of COPO. We studied two groups of petlents: 44 patients admitted to the hospital with acute exacerbations of COPO, and 65 stable clinic patients with COPO. we found that evidence of acute TWAR Infection was Infrequent In patients with exacerbstlons (5%). In contrast, the majority of patients from both groups had serologic evidence of previous TWAR Infection (77%). This was not significantly greater than the prevalence found In a small group of patients of similar age and aex without lung dlaease from Ihe seme Institution (73%). TWAR was not Isoleted from the oropharyngealspeclmena obtained from W sublects, suggesting that It does not colonize the respiratory tract of patients with COPO.This study shows that at the time of low Incidence In the community, acute TWARInfection Is uncommon In patients with acute exacerbations of COPO.The majority of patients with COPOhave, however, been Infected with TWAR In the past. The clinical manifestations of these Infections are not known and should be the focus of further studies. AM REV RESPIR DIS 1991; 144:1408-1410
the Seattle Veterans Administration Medical Center from February 1987 to February 1988 with exacerbations of COPD. Admitting records were reviewed daily to identify patients who had been admitted in the previous 24 h with respiratory complaints. The charts of all such patients were evaluated for evidence that the patient had COPD. An acute exacerbation of COPD was defined as the new onset of dyspnea or a worsening of chronic dyspnea in a patient with known COPD and without an alternate explanation for their symptoms. Accordingly, patients with COPD were excluded from the study if they had clinical findings of congestive heart failure or dyspnea related to other causes (i.e., metabolic acidosis, severe anemia, neuromuscular diseases). To maximize the likelihood of identifying acute C. pneumoniae infection, we also excluded patients if they had received antibiotics in the 2 wk prior to enrollment or had an acute respiratory illness in the 2 months prior to enrollment. We screened 186 patients and enrolled 44. The reasons for exclusion were: recent respiratory illness (48010), congestive heart failure (10010), recent antibiotic therapy (3010). Only 5010 refused to participate. Forty-one (35010 of those excluded) were excluded either because they did not have COPD or because, despite the diagnosis on the admitting records, they had COPD but were not admitted with a change in their respiratory symptoms. Group 2: A random sample of pulmonary clinic patients was evaluated between December 1987and March 1988. Every third chart, by hospital number, was reviewed for evidence of COPD. All patients with this diagnosis were considered for participation in the study. The exclusion criteria were the same as for the patients in Group 1. We screened 116patients and enrolled 65. Patients were excluded because ofrecent respiratory illness (63010) and recent antibiotic therapy (6010). Nine (18010) of the patients who were randomly selected failed to keep their clinic appointment. Seven patients (14010) refused to participate.
Group 3: Between April and July 1988 we screened patients in the Seattle Veterans Administration Medical Center Urology Clinic who were between 45 and 70 yr of age for evidence of airflow obstruction. We performed simple spirometryon 31 patients using a BREON spirometer to ensure that they did not have occult airflow obstruction. Patients were excluded if they had a FEV 1 less than 80010 predicted, a FVC less than 80010 predicted or FEV./FVC less than 0.75. Additional exclusion criteria were the same as for Groups 1 and 2. We identified 24 patients without airflow obstruction who were similar in age and of the same sex as the patients with COPD and who were willing to participate in the study. Patients in all groups were interviewed by the study coordinator at the time of entry into the study. All patients answered the same predetermined questions. Baseline pulmonary function tests were available for the majority of Group 1 and 2 patients. Pertinent laboratory values and chest radiographs were obtained on all Group I patients. Radiographs were interpreted independently by two of the investigators.
(Received in original form January 28, 1991 and in revised form May 30. 1991) • From the Medical Service, Seattle Veterans Administration Medical Center, and the Departments of Medicine, Epidemiology, and Pathobiology, University of Washington, Seattle, Washington. • Supported in part by Public Health Service Research Grant AI-21885 from the National Institutes of Health. 3 Correspondence and requests for reprints should be addressed to Christopher D. Beaty, M.D., Department of Medicine, Division of Pulmonary and Critical Care Medicine RM-12, University of Washington, Seattle, WA 98195.
BRIEF COMMUNICATION
1409 TABLE 1
CLINICAL CHARACTERISTICS OF THE STUDY POPULATION
Age, mean ± SD Sex, M:F Home oxygen use, n (%) Chronic steroid use, n (%) Previously hospitalized for COPD, n (%) History of chronic bronchitis, n (%) Findings on presentation Temperature> 37.7° C, n (%) WBC > 10 K, n (%) Lung infiltrate
Group 1 (n = 41)*
Group 2
Group 3
(n = 65)
(n = 24)
67.9 ± 5.7 39:2 11 (27) 11 (27)
65.5 ± 7.5 63:2 7 (11) 16 (25)
62.7 ± 6.0 21:3
28 (68)
36 (55)
11 (27)
12 (18)
3 (7) 26 (63)
o
• Data not available for three subjects.
TABLE 2 BASELINE PULMONARY FUNCTION TESTS Group 1 (n
FEV" ml FEV,. %t FVC, ml FVC,% FEV,/FVC
1.03 45.68 2.45 58.69 40.6
Group 2
= 25) ± ± ± ± ±
(n
0.52:1: 32.39 0.69 18.02 16.4
1.42 53.29 2.88 64.5 47.4
Group 3'
= 53) ± ± ± ± ±
(n
0.73:1: 34.83 0.93 19.53 14.0
3.02 96.65 3.80 85.79 79.4
= 24) ± 0.43 ± 11.9 ± 0.67
± 10.79 ± 6.6
• All Group 3 values were significantly greater than the values in either Group 1 or Group 2. t Denotes percentage predicted based on height, age, and sex. Denotes statistically significant difference between Group 1 and Group 2.
*
TABLE 3 ANTIBODY AGAINST TWAR IN SUBJECTS WITH ACUTE EXACERBATION OF COPD (GROUP 1), WITH STABLE COPD (GROUP 2), OR WITHOUT COPD (GROUP 3)
(n
Group 1 (27)'
= 44)
(n
Group 2 (44)*
Group 3 = 24)
= 65)
(n
Antibody
(n)
(%)
(n)
(%)
(n)
(%)
Acute Preexistingt
2 43
5 81
0 50
rr
2 16
8 73
• Number of patients with paired serum specimens. all others single serum specimens. Percent preexisting antibody is determined with persons with acute antibody removed from denominator.
t
Efforts to obtain paired sera at 2- to 3-month intervals were made for all subjects in Groups 1 and 2. Subjects in Group 3 had a single serum sample obtained at the time of enrollment. All blood was tested for TWAR-specific IgG and IgM antibody using a microimmunofluorescence (micro-IF) test (1, 10), Current or recent TWAR infection was defined as a fourfold rise in antibody titer in either the IgM or IgG serum fraction, a titer of > 1:16 in the IgM serum fraction, or ;;. 1:512in the IgG fraction. Past TWAR infection was defined by an IgG titer of 1:16 to 1:256. Throat swab specimens suitable for culture were obtained from 32 Group I patients and all Group 2 patients. They were placed in Chlamydia transport media for culture and frozen at -70· C within 30 min of the time they were obtained. Isolation was performed using HeLa 229 cells (11).
The clinical characteristics of the subjects in each group are shown in table 1. Most of the subjects were men with an overall male to female ratio of 25:1. As expected, subjects were
in the older age groups with mean ages of 63 to 68 yr. Oxygen use, steroid use, smoking history, presence of chronic bronchitis, and number of hospital admissions in the previous 2 yr were similar in Groups 1 and 2. Pertinent clinical data were available for all but three Group 1 patients. Feverwas uncommon, but two thirds of the patients had elevated white blood cell counts. No patient had a new chest radiographic infiltrate. The results of baseline pulmonary function tests for patients in each of the three groups are shown in table 2. Baseline pulmonary function tests were available for 25 Group I patients (66070),53 Group 2 patients (81070), and all Group 3 patients. Patients in Groups I and 2 had severe airflow obstruction, with mean FEY, values of 1.03 and 1.42 Lis, respectively. The absolute values for FEY, were significantly lower in Group 1 than in Group 2; however, the difference was not sig-
nificant when expressed as a percentage of predicted based on height, weight, age, and sex. The patients in Group 3 had normal pulmonary function tests, consistent with the selection criteria. Paired serum samples were obtained in 27 Group 1 and 44 Group 2 patients. The remainder had one sample drawn at the time they wereenrolled. The mean interval between acute and convalescent samples was 12.6 (± 2.7) wk for those in Group 1 and 18.7 (± 8.1) wk for those in Group 2. The TWAR microimmunofluorescence serologic results are shown in table 3. Antibody suggesting recent infection was found in two Group 1 patients and in two Group 3 patients. In each group one had IgM antibody and one had high titer IgG antibody (~ 1:512). Preexisting antibody (lgG 1:16 to 1:256) was found in the majority of subjects and was equally distributed (73-81 0J0) through the three groups. Neither of the Group 1 patients with acute TWAR antibody had fever, leukocytosis, or a radiographic infiltrate during their hospitalization. Neither patient in Group 3 with serologicevidence of TWARinfection recalled any recent illness. Culture of throat swab specimens was successfully carried out on 30 of the hospitalized patients, including the two with acute TWAR antibody, and all were negative for C pneumoniae. Cultures wereobtained from 59 of the clinic patients, and the results were negative in all of them. When the clinical characteristics of all patients with COPD without preexisting TWAR antibody were compared, there wereno differences in their use of oxygen, steroids, or cigarettes. Pulmonary functions were similar in those with and without antibody as was the prevalence of chronic bronchitis and history of prior hospitalizations for exacerbations of COPD.
**** The primary goal of this study was to determine whether TWAR is a common cause of exacerbations of airflow obstruction in adult patients with CO PD. The selection criteria resulted in a narrowly defined group of patients in whom exacerbations of airflow obstruction were due to acute bronchitis without an obvious bacterial pathogen in the sputum. For comparison, a group of patients with similar degrees of airflow obstruction who were clinically stable and a group of patients who are free of lung disease as detected by questionnaire and screening spirometry were studied. We found that TWAR was an uncommon pathogen in this group of patients evaluated during 1987 and 1988.Only two of 44 patients with exacerbations had serologic evidence of acute TWAR infection, but the organism was not isolated from either patient. These findings indicate that, during the period of study, acute TWAR infection was not a common cause of exacerbations of COPD.
BRIEF COMMUNICATION
1410
1\vo methods of TWAR infection have been postulated, person-to-person spread of respiratory secretions and endogenous reinfection from dormant organisms in the respiratory tract (12). 1\vo factors may have reduced our chances of detecting person-to-person transmission of TWAR. First, from other investigations we learned that at the time of this study there was a low incidence of acute TWAR infection in the Seattle area. TWAR infections are periodic, with several years of higher incidence followed by years of low incidence (6). It is possible that more cases of acute TWAR might have been detected during another period in Seattle. Second, we excluded patients with recent respiratory infections and those who had been using antibiotics. Weexcluded patients with recent antibiotic therapy in order to avoid masking the TWAR culture results. These exclusion criteria could have eliminated some patients with acute TWAR infections from our study population. TWAR respiratory tract infection often has a subacute or biphasic onset, with lower respiratory tract involvement beginning later in the course of the disease. Some ofthe patients excluded for prior respiratory infection might have had TWAR infection associated with their hospitalization. This study provides some evidence against a significant role for relapse TWAR infection in COPD exacerbations. Such infections would not be influenced by the low community incidence of TWAR infection and should therefore be more prevalent in a population such as ours where the majority of patients have serologic evidence of previous infection. The low prevalence of acute TWAR infection in this study argues against this mechanism of infection. Similarly, our failure to isolate the organism from the oropharynx of these patients with COPD argues against (but does not disprove) the presence of latent TWAR respiratory tract infection or colonization. The finding of TWAR antibody indicating previous infection in 770/0 of patients with
COPD is the highest prevalence that we have found. The group of 24 patients without chronic lung disease who were tested had a prevalence of preexisting TWAR antibody (73%) similar to that of the patients with COPD. Two of these urology clinic patients had antibodies suggesting current or recent TWAR infection. There is no explanation for this surprising finding, and it raises a question about how good a comparison group these patients are. The prevalences in all three groups were much higher than the 53% prevalence observed in age-matched patients admitted with pneumonia to the same institution during 1980 and 1981 (12). Similarly, when patients in several other earlier Seattle area acute respiratory disease studies (4) were age- and sex-matched with our patients with COPD, a significantly lower antibody prevalence was found (57%), but when similar matching was done with patients from a Seattle area coronary artery disease study (13), the rate found (67%), although lower, was not a statistically significant difference (chisquare for differences in proportions using an average weighted by sample size, with age adjusted to the patients with COPD). These studies were carried out at different times, and the periodicity of TWAR infection may cause time-related differences in antibody prevalence. We cannot say that patients with COPD have a higher prevalence of preexisting TWAR antibody, but we can confidently say that most of our patients with COPD have been infected with TWAR in the past. The clinical manifestations of these infections remain to be defined leaving the possibility that TWAR could be a cause of significant morbidity in this population of patients with compromised pulmonary function.
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1986; 315:161-8. 2. Grayston JT, Kuo CC, Campbell LA, Wang SP. Chlamydia pneumoniae sp. nov. for Chlamydia sp. strain TWAR. Int J Syst Bacteriol1989; 39:88-90. 3. Li DK, Daling JR, Wang SP, Grayston JT. Evidencethat Chlamydiapneumoniae, strain TWAR, is not sexually transmitted. J Infect Dis 1989; 160:328-31. 4. Wang SP, Grayston JT. Population prevalence antibody to Chlamydia pneumoniae, strain TWAR. In: Bowie WR, Caldwell HD, Jones RP, et al., eds. Chlarnydial infections. Cambridge: Cambridge University Press. 1990; 402-5. 5. Saikku P, Wang SP, Kleemola M, Brander E, Rusanen E, Grayston JT. An epidemicof mild pneumonia due to an unusual strain of Chalmydia psittaci. J Infect Dis 1985; 151:832-9. 6. Grayston JT, Campbell LA, Kuo CC, et al. A new respiratory tract pathogen: Chlamydia pneumoniae, strain TWAR. J Infect Dis 1990; 161:618-25. 7. Tager I, Speizer FE. Role of infection in chronic bronchitis. N Eng! J Med 1975; 292:563-71. 8. Anthonisen NR, Manfreda J, Warren CPW, Hershfield ES, Harding GKM, Nelson NK. Antibiotic therapy in exacerbations of chronic obstructive pulmonary disease. Ann Intern Med 1987; 106:196-204. 9. Nicotra MB, Rivera M, AweRJ. Antibiotic therapy of acute exacerbations of chronic bronchitis: a controlled study using tetracycline. Ann Intern Med 1982; 97:18-21. 10. Wang SP, Grayston JT. Immunologic relationship between genital TRIC, lymphogranuloma venereum, and related organisms in a new microtiter indirect immunofluorescence test. Am J Ophthalmol 1970; 70:367-74. 11. Kuo CC, Grayston JT. Factors affecting viability and growth in HeLa 229 cells of Chlamydia sp, strain TWAR. J Clin Microbiol1988; 26:812-15. 12. Grayston JT, Diwan VK, Cooney M, Wang SP. Community- and hospital-acquired pneumonia associated with Chlamydia TWAR infection demonstrated serologically. Arch Intern Moo 1989; 149:169-73. 13. Thorn DH, Wang SP, Stewart DK, Grayston JT. Chlamydia pneumoniaestrain TWAR antibody and angiographically demonstrated coronary artery disease. In: Bowie WR, Caldwell HD, Jones RP, et al. eds. Chlamydial infections. Cambridge: Cambridge University Press, 1990; 453-6.
