Chlamydia pneumoniae is an important cause of community-acquired pneumonia in school-aged children: serological results of a prospective, population-based study.

The aetiology of community-acquired pneumonia in childhood was studied in the total population of 8851 children in the area of 4 municipalities in eastern Finland. All cases of community-acquired pneumonia (n = 201) were registered during a surveillance period of 12 months between September 1, 1981 and August 31, 1982. The diagnosis of pneumonia was verified radiologically in all identified cases. The diagnosis of chlamydial infection was based on an antibody response measured by complement fixation (CF), by enzyme immunoassay (EIA; IgG or IgM) or by microimmunofluorescence (MIF; IgG or IgM), and the diagnosis of mycoplasmal infection on CF alone. In total, 29 cases of Chlamydia sp. infection were diagnosed; 20 were caused by Chlamydia pneumoniae. Thus, C. pneumoniae was an aetiological agent in 10%, of the 201 pneumonia cases: the proportion was 9% for children aged 5-9 y and 31% for those aged 10 y or more. In the study population, the total incidence of C. pneumoniae pneumonia was 2.3/1000/y. Mycoplasma pneumoniae serology (CF) was positive in 44 patients (22%); the total incidence of M. pneumoniae pneumonia was 5.0/1000/y. Serological evidence of both Chlamydiae and M. pneumoniae was detected in 9 (41%) patients. Our results indicate that C. pneumoniae is an important cause of community-acquired pneumonia in school-aged children. Diagnostic serological response to Chlamydia species or M. pneumoniae was found in 42% of pneumonia patients between 5 and 9 y of age and in 67% of patients aged 10 y or more. Thus, we suggest that macrolides should be considered as an empirical antimicrobial treatment for community-acquired pneumonia, especially in school-aged outpatients.     

Mycoplasma pneumoniae and Chlamydophila pneumoniae in children with community-acquired pneumonia in Thailand.

BACKGROUND: The prevalence of community-acquired pneumonia (CAP) caused by atypical pathogens in Thai children is unknown. OBJECTIVE: To examine the prevalence of Mycoplasma pneumoniae and Chlamydophila pneumoniae infections in paediatric patients (aged 2-15 years) with CAP in three academic hospitals using standardised laboratory techniques. The characteristics of atypical pneumonia were also compared with other causes of CAP. METHODS: Diagnosis of current infection was based on a four-fold or more rise in antibody serum samples or persistently high antibody titres together with the presence of mycoplasmal or chlamydial DNA in secretions. RESULTS: Of 245 patients with CAP, 17.5% of cases were caused by atypical pathogens (M. pneumoniae 14.3%, C. pneumoniae 2.8% and co-infection 0.4%). We also found atypical pathogens in young children aged 2-5 years. The clinical and laboratory findings did not distinguish atypical pneumonia from other CAPs. Segmental or lobar consolidation on chest X-rays was more common in atypical pneumonia, while dyspnoea was more prominent in other CAPs. CONCLUSION: Our data show a high prevalence of M. pneumoniae and C. pneumoniae in Thai children with CAP, including in children aged 2-5 years.     

Clinical observations of children with pleuropneumonia due to Mycoplasma pneumoniae

A comparative study on the clinical presentation of Mycoplasma pneumoniae infection was performed in 56 patients with pleuropneumonia and those who had pneumonia without pleural effusion. The latter consisted of 773 cases; their age distribution reached a peak at 3-5 years of age in males and at 4-6 years in females. The 56 cases with pleuropneumonia were distributed among children of all ages. Pneumococcal infection was demonstrated by blood culture in one of 56 cases. Serological tests revealed a higher prevalence of mixed viral infections among children with pleuropneumonia (18/44) than with pneumonia but no effusion (69/419). There was a tendency toward a severe and prolonged course of illness with strong indications of infection among pleuropneumonia cases. Complications such as exanthema or liver dysfunction were observed more frequently among pleuropneumonia cases than among simple pneumonia cases. These results suggest that other pathogenic agents or unknown host reactions to these agents may modify the clinical picture of pleuropneumonia caused by M. pneumoniae.     

Macrolide-resistant Mycoplasma pneumoniae in adolescents with community-acquired pneumonia

ABSTRACT: BACKGROUND: Although the prevalence of macrolide-resistant Mycoplasma pneumoniae isolates in Japanese pediatric patients has increased rapidly, there have been no reports concerning macrolideresistant M. pneumoniae infection in adolescents aged 16 to 19 years old. The purpose of this study was to clarify the prevalence and clinical characteristics of macrolide-resistant M. pneumoniae in adolescent patients with community-acquired pneumonia. METHODS: A total of 99 cases with M. pneumoniae pneumonia confirmed by polymerase chain reaction (PCR) and culture were analyzed. Forty-five cases were pediatric patients less than 16 years old, 26 cases were 16 to 19-year-old adolescent patients and 28 cases were adult patients. Primers for domain V of 23S rRNA were used and DNA sequences of the PCR products were compared with the sequence of an M. pneumoniae reference strain. RESULTS: Thirty of 45 pediatric patients (66%), 12 of 26 adolescent patients (46%) and seven of 28 adult patients (25%) with M. pneumoniae pneumonia were found to be infected with macrolide-resistant M. pneumoniae (MR patients). Although the prevalence of resistant strains was similar in pediatric patients between 2008 and 2011, an increase in the prevalence of resistant strains was observed in adolescent patients. Among 30 pediatric MR patients, 26 had an A-to-G transition at position 2063 (A2063G) and four had an A-to-G transition at position 2064 (A2064G). In 12 adolescent MR patients, 10 showed an A2063G transition and two showed an A2064G transition, and in seven adult MR patients, six showed an A2063G transition and one showed an A2064G transition. CONCLUSIONS: The prevalence of macrolide-resistant M. pneumoniae is high among adolescent patients as well as pediatric patients less than 16-years old. To prevent outbreaks of M. pneumoniae infection, especially macrolide-resistant M. pneumoniae, in closed populations including among families, in schools and in university students, physicians should pay close attention to macrolide-resistant M. pneumoniae.     

Atypical pathogens in adult patients admitted with community-acquired pneumonia in Korea

This study examined the prevalence of atypical pathogens causing community-acquired pneumonia (CAP) in Korea. We collected sera and clinical data for a period of 1 year for the adult patients consecutively admitted to Chunchon Sacred Heart Hospital with CAP. The diagnosis was made using serologic methods to detect antibodies for Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella spp., Chlamydia psittaci, and Coxiella burnetii. Among 81 recruited patients, C. pneumoniae (n = 10, 12.3%) was the leading cause of illness, followed by M. pneumoniae (n = 7, 8.6%). One case of C. burnetii pneumonia was detected, but there were no cases of Legionella spp. or C. psittaci. Three cases of C. pneumoniae pneumonia were co-infected with either M. pneumoniae or C. burnetii. There was no significant difference between atypical pneumonia and non-diagnosed pneumonia in terms of clinical manifestations. In conclusion, of the atypical pathogens causing CAP, C. pneumoniae and M. pneumoniae appear to be the important etiologic pathogens in Korea.     

Multicenter screening of Chlamydia pneumoniae pneumonia by ELISA method

We prospectively investigated the etiology of community-acquired pneumonia among adult patients admitted to three general hospitals over one year. Antibody titers to Chlamydia pneumoniae were also measured by ELISA method to investigate the incidence and clinical pictures of C. pneumoniae pneumonia in Japan. Two hundred and fourteen patients were enrolled in the study. Seventeen patients (7.9%) satisfied the criteria for diagnosis of acute infection due to C. pneumoniae by ELISA method. C. pneumoniae was the 3rd leading causative agent following Streptococcus pneumoniae (21.5%) and Haemophilus influenzae (8.4%). Preexisting antibodies were detected in 62.1% of the patients. Most of the patients with C. pneumoniae pneumonia were aged, and had comorbidities of respiratory system. Superinfection with bacterial pneumonia was recognized in some patients. Though there are several problems, ELISA method is thought to be useful to diagnose C. pneumoniae pneumonia, and is suitable for screening tests.     

Simkania negevensis in community-acquired pneumonia in Italian children

Simkania negevensis, a recently found Chlamydia-like organism, has been associated with respiratory infections in children and adults with pneumonia, but S. negevensis findings have been common also without any infection. The aims of the present paper were to evaluate S. negevensis in the aetiology of paediatric community-acquired pneumonia (CAP), its seroprevalence in north Italian children, and whether there is cross-reactivity between S. negevensis and Chlamydia pneumoniae serology. Antibodies to S. negevensis were measured by microimmunofluorescence (MIF) in 101 frozen paired sera obtained from children with CAP. Serological evidence (> or =4-fold increase or decrease in IgM or IgG) of acute S. negevensis infection was achieved in 5 (5%) cases. Two were mixed infections with Mycoplasma pneumoniae and 1 with respiratory syncytial virus. In total, 20-30% of the children had measurable antibodies to S. negevensis, with no association with age. No cross-reactivity was observed between antibodies to S. negevensis and C. pneumoniae. S. negevensis appears to be a real, though rare, cause of CAP in children.     

Etiology of community acquired pneumonia among adult patients requiring hospitalization in Taiwan

BACKGROUND: There has not been a comprehensive multi-center study investigating the microbial profile of community acquired pneumonia (CAP) in Taiwan. METHODS: A prospective study of adult CAP patients requiring hospitalization between December 2001 and April 2002 was carried out in 13 hospitals in Taiwan. Etiology was determined based on laboratory data from blood and sputum cultures plus serology from paired serum and urine antigen detection tests. RESULTS: Etiology was assigned to 99 (58.9%) of the 168 patients having the most complete data for etiology determination, with mixed infection in 21 (12.5%) patients. More than half (51.8%) of the patients were>60 years and 63.7% of the patients were males. The most common etiologic agent was Streptococcus pneumoniae (40, 23.8%), the majority (60%, 24 cases) of which was detected by positive urine antigen test. Other common agents included Mycoplasma pneumoniae (24, 14.3%), Chlamydia pneumoniae (12, 7.1%), Influenza A virus (11, 6.5%), Klebsiella pneumoniae (8, 4.8%) and Haemophilus influenzae (8, 4.8%). The prevalence of S. pneumoniae and M. pneumoniae was highest in patients>60 years (25/87, 28.7%), and<44 years (12/59, 19%), respectively; while K. pneumoniae comprised a larger proportion (4/22, 18%) in the 45-59 years group. CONCLUSIONS: S. pneumoniae was the most common etiology agent in adult patients hospitalized due to CAP in Taiwan and the spectrum of other major pathogens was similar to studies conducted elsewhere in the world. Empiric treatment recommendations developed in other parts of the world may be appropriately adapted for local use after taking into account local resistance profiles. Our data also support the recommendation that urine antigen test be added as an adjunct to adult CAP etiology diagnosis protocol.     

Chlamydia pneumoniae in community-acquired pneumonia: seven years of experience

OBJECTIVES: To determine the prevalence of Chlamydia pneumoniae in community-acquired pneumonia during a period of seven years. METHODS: Serum samples from 311 patients with pneumonia were evaluated using microimmunofluorescence assay to detect C. pneumoniae -specific IgG and IgM antibodies. RESULTS: Thirty nine patients (12.5%) complied with the diagnostic criteria of acute C. pneumoniae infection (a four-fold rise in the titer of IgG antibody, or a single IgG titer > or = 1:512, or a single IgM titer > or = 1:16). All patients were diagnosed as having pneumonia. Co-infection with other respiratory tract pathogens was found in four patients. CONCLUSIONS: C. pneumoniae is an important cause of pneumonia also in our area. Pneumonia due to this bacterium occurs in the cold months and in early spring; in addition we have observed periods of increased incidence of one years duration and periods of low incidence lasting one-two years. Therapy with macrolides and levofloxacin was effective in all patients with C. pneumoniae infection.     

Seroprevalence of Chlamydia pneumoniae infection in Taiwan

OBJECTIVES: To survey the seroprevalence of Chlamydia pneumoniae (C. pneumoniae) infection in healthy subjects in Taiwan. MATERIALS AND METHODS: We used microimmunofluorescence antibody assay to survey the prevalence of antibodies to C. pneumoniae in 620 serum samples from healthy subjects aged 6 months to 86 years in Taiwan. RESULTS: The mean prevalence (+/-SD) of IgG antibodies against C. pneumoniae at titer greater than or equal 1:16 was 55.8% (range 7.8-81.8%). The antibody prevalence was low in children under the age of 10 years (7.8%), and increased rapidly with age. Most individual acquired infection during the second and third decades of life with highest antibody prevalence reached up to 81.8% at fifth decade of life and remained high (70%) thereafter. CONCLUSIONS: Chlamydia pneumoniae infection is highly endemic in Taiwan. These data contribute to the understanding of asymptomatic infections with C. pneumoniae in general population and should serve as a basis for studies on the role of C. pneumoniae infections and their related diseases.     

Chlamydophila pneumoniae infection among young children with respiratory diseases in Thailand

A total of 136 children aged 5 years and under with respiratory tract diseases were examined for Chlamydophila pneumoniae infection. By means of the micro-immunofluorescence test, an acute infection was suggested in 37 (27.2%) of them. Infection was found in 23 (43.4%) of 53 children with bronchitis, seven (70.0%) of 10 with pharyngitis, and two (22.2%) of nine with pneumonia. C. pneumoniae DNA was detected in seven of 55 children by means of nasopharyngeal swabs, and serological evidence was present in all of seven. Five of them were suggested the acute infection and four of the five showed IgG titers increasing four times and over. By age distribution, five of the seven DNA-positive children were 1 year old, and the remaining two were 2 and 4 years old, respectively. The clinical findings of the seven DNA-positive children were characterized as indicative of bronchitis (n = 4), pharyngitis (n = 2), and pneumonia (n = 1). In Thailand, C. pneumoniae infection occurs frequently among children aged 5 years and under, and may cause pharyngitis, bronchitis, and sometimes pneumonia. However, it is suggested that C. pneumoniae infection is not a major cause of severe pneumonia among children in that age group.     

肺炎衣原体急性呼吸道感染的临床研究

目的了解成人呼吸道感染患者急性肺炎衣原体感染的患病情况及临床特征。方法呼吸道感染住院患者１１０例，同时采集痰和咽拭子标本，应用聚合酶链反应（ＰＣＲ）检测肺炎衣原体ＤＮＡ，及采取静脉血检测肺炎衣原体ＩｇＧ和ＩｇＭ抗体。结果本组患者肺炎衣原体ＩｇＧ抗体的阳性率为７０％（７７／１１０），其中１７例（１６％）有肺炎衣原体近期感染的急性抗体，１２例（１１％）痰和（或）咽拭子肺炎衣原体ＰＣＲ检测结果阳性，联合应用两种方法的阳性率为２３％（２５／１１０）。肺炎衣原体急性感染以支气管哮喘急性发作、肺炎、慢性阻塞性肺疾病急性加重和急性支气管炎患者多见（分别为５７％、３５％、２６％和２５％），其临床表现无特征性。结论结果提示成人呼吸道感染患者肺炎衣原体急性感染的阳性率较高，提示肺炎衣原体是呼吸道感染的重要致病原，应引起临床的高度重视     

Antibodies to Chlamydia pneumoniae in young Swedish orienteers

During 1992-93 sera from 1790 Swedish elite orienteers were tested for antibodies to Chlamydia pneumoniae. The reason for this was that a cluster of 16 cases of sudden unexpected cardiac death had occurred among Swedish orienteers and DNA from C. pneumoniae had been found in the myocarditic heart and in the lung in 1 of 2 deceased athletes in whom testing was feasible; in addition, C. pneumoniae IgG was found in all 5 cases where serum was available. Among the orienteers, the prevalence rates of IgG antibodies in males and females were 54% (n = 1194) and 50% (n = 596), respectively. The corresponding figures for 319 male and female blood donors were 60% (n = 169) and 53% (n = 150), respectively. These differences are not statistically significant. Male orienteers had a lower prevalence of IgA antibodies than male blood donors (19% and 26%, respectively; p < 0.05), while no such difference was found in females (16% and 18%). The prevalence of IgM antibodies was < 1% in all groups. Neither the performance level of the orienteers nor the place of residence affected the antibody prevalence. In conclusion, Swedish orienteers do not show a higher prevalence of antibodies to C. pneumoniae than healthy blood donors.     

Seroprevalence of anti-Helicobacter pylori and anti-CagA antibodies among healthy children according to age, sex, ABO blood groups and Rh status in south-east of Iran.

Background/aims: The aim of this study was to evaluate the seroprevalence of anti-Helicobacter pylori (H. pylori) and anticytotoxin associated antigen A (CagA) antibodies in healthy children and to investigate the relation with age, sex, ABO blood groups and Rh status. Methods: Serum samples from 386 children (187 males, 199 females), aged 1-15 years, were tested for the presence of antibody to H. pylori and its virulence factor (CagA) by use of ELISA. ABO blood grouping was also done by hemagglutination test. Results: The overall seroprevalence of H. pylori infection was 46.6%. The prevalence of anti-H. pylori antibody was significantly (p<0.05) higher in males (51.9%) compared to females (41.7%). The prevalence of anti-CagA antibody in infected children was 72.8%. Although the prevalence of anti-CagA antibody was higher in males (78.4%) compared to females (66.3%), the difference was not statistically significant (p=0.07). In age subgroups of 1-5 years, 6-10 years and 11-15 years, the prevalence of anti-H. pylori was 37.6%, 46.9% and 54.9% and in infected children, the prevalence and the mean titer of anti-CagA antibody were 63.8%, 75.94 Uarb/ml; 75%, children acquire H. pylori infection. Anti-CagA common in the children. The seroprevalences of and anti-CagA antibodies were higher in males with age. However, the mean titer of anti-CagA decreased with increasing age. ABO blood groups influence the prevalence of H. pylori infection, especially gender..     

Chlamydia pneumoniae infection in adults with chronic cough compared with healthy blood donors.

In a small uncontrolled study, persistent cough has recently been found to be associated with serological evidence of acute Chlamydia pneumoniae infection. In order to assess whether C. pneumoniae plays a role in chronic cough, the prevalence of C. pneumoniae infection in 201 adult patients with chronic cough was compared with the prevalence in 106 healthy blood donors without respiratory tract symptoms in the preceding 3 months. A microimmunofluorescence antibody test was used to determine C. pneumoniae antibodies in the immunoglobulin (Ig)M, IgG and IgA fractions. Further, nasopharyngeal aspirates from the 201 patients were examined for C. pneumoniae deoxyribonucleic acid by polymerase chain reaction (PCR). As judged by serology, nine patients (4%) and one control (1%) had acute C. pneumoniae infection, and 92 patients (46%) and 42 controls (40%) had previous or chronic C. pneumoniae infection. Of the nine patients with acute infection, three were C. pneumoniae PCR positive, and they all had an IgM antibody titre response. The remaining six patients had either an IgG antibody titre of > or =512 (five patients) or an IgA antibody titre of > or =512 (one patient). None of these six patients had detectable IgM antibodies. The mean cough period for the five IgG positive patients (10.8 weeks) was significantly longer than the mean cough period for the remaining patient population (6.4 weeks; p=0.004). It is concluded that Chlamydia pneumoniae infection was not statistically significantly more prevalent in patients with chronic cough than in healthy blood donors, and that Chlamydia pneumoniae appears to have a minor role in patients with chronic cough. Direct detection of Chlamydia pneumoniae by polymerase chain reaction on nasopharyngeal aspirates is highly correlated with detectable immunoglobulin M antibodies, but in the late stages of prolonged cough serological testing of immunoglobulin G and immunoglobulin A may be more beneficial for obtaining a microbiological diagnosis.     

五指山地区儿童肺炎支原体感染流行特点及与气候因素相关性研究

目的 探讨五指山地区儿童急性呼吸道肺炎支原体(MP)感染流行特点及与气候因素的关系。方法 检测2015年1月至2016年12月门诊和住院的1 597例呼吸道感染患儿血清肺炎支原体特异性IgM(MP-IgM),同时收集同期的气象资料,采用多元线性回归分析研究 MP-IgM 检出率与气候因素的相关性。结果 MP-IgM总检出率为25.05%; 0~1 岁、~3 岁、~6 岁、> 6 岁患儿的 MP-IgM 阳性率分别为6.70%、30.80%、36.90% 和43.40%;男性 27.54%,女性阳性率21.78%; 春、夏、秋、冬四季阳性率分别为22.95%、35.91%、28.89% 和17.07%;以上年龄、性别、季节的差异均有统计学意义(P< 0.01)。月平均气温、月总雨量与 MP-IgM 检出率呈正相关(P=0.001)。结论 MP为五指山地区儿童呼吸道感染主要病原体之一,学龄前儿童及学龄期儿童为易感人群,不同季节MP感染率不同,夏秋季节为高发期,高气温、高雨量是促进 MP感染流行的主要气候因素。     

Onchocerciasis in Ecuador. II. Epidemiology of the endemic foci in the province of Esmeraldas

The epidemiology of infection was studied in all endemic foci of onchocerciasis in the province of Esmeraldas in Ecuador. The incidence of infection and the density of microfilariae in the skin, both greater in males than females, increased with age, reaching highest levels at 40-45 years in males and at 60 years and older in females. In the hyperendemic area males and females had the same rate of infection, but the microfilarial density in males exceeded that in females. In the hypoendemic areas males had a higher infection rate than females, but females registered a higher density of microfilariae in the skin. The incidence and location of the onchocercal nodules correlated closely with the density of microfilariae. Adults, aged 50-54 had the highest prevalence of onchocercal nodules, which occurred primarily in the thorax and pelvic regions. Children aged 0-14 years showed a low prevalence of nodules, the head region being the primary site. Of the two diagnostic methods used to detect the presence of microfilariae, most of the diagnoses (85.6%) were made by skin biopsies as compared to those made by the Mazzotti test (14.4%).     

Acute purulent exacerbation of chronic obstructive pulmonary disease and Chlamydia pneumoniae infection.

In order to investigate the role of bacteria, including Mycoplasma pneumoniae and especially Chlamydia pneumoniae in acute purulent exacerbations of chronic obstructive pulmonary disease (COPD), we examined sputum specimens and acute and convalescent sera taken 26 d apart from 49 outpatients experiencing an acute purulent exacerbation of COPD. The sera were tested for antibodies to C. pneumoniae with the microimmunofluorescence test, and for antibodies to M. pneumoniae with the indirect fluorescence antibody test. Routine microbiologic culture of sputum yielded potentially pathogenic microorganisms in 12 of the 49 patients (24%). Three patients (6%) showed serologic evidence of recent M. pneumoniae infection. Seven patients showed high IgG titers of >/= 1:1,024 to C. pneumoniae, and an additional four had a fourfold increase in IgG titer, suggesting reinfection with C. pneumoniae. Sputum from two of these 11 patients also grew Streptococcus pneumoniae, and one grew Moraxella catarrhalis. Patients with and without serologic evidence of current C. pneumoniae infection showed no significant differences in clinical features or pulmonary function. The high incidence of infection with C. pneumoniae (the sole causal agent in 16% of cases, and the causal agent with other agents in 6%) provides insight into the importance of this organism among agents leading to exacerbations of COPD in Turkey.     

Chlamydia pneumoniae and Mycoplasma pneumoniae in children with acute respiratory infection in general practices in The Netherlands

In this retrospective study Chlamydia pneumoniae and Mycoplasma pneumoniae infections were detected by polymerase chain reaction (PCR) in samples (n = 457) from children presenting with acute respiratory infection to general practitioners during 1992-97. Samples were collected in autumn and winter, and from 1994 onwards in spring and summer also. Overall, C. pneumoniae and M. pneumoniae were detected in throat or nasal samples by PCR in 3.1% and 2.4% of the cases, respectively. The proportion of both C. pneumoniae and M. pneumoniae infections varied between 0% and 6.9% over the years studied, whereas seasonal proportions varied from 1.8 to 9.1% and 1.2 to 4.5%, respectively. For both microorganisms the lowest proportion was detected during winter and the highest in summer. C. pneumoniae could already be detected by PCR in patients under 4 y of age, an observation not made in sero-epidemiological studies. In conclusion, both C. pneumoniae and M. pneumoniae infections play a minor role in children presenting with acute respiratory infection.     

Effect of age on antibody titer to Mycoplasma pneumoniae

Between January 1996 and September 1999, 13,650 serum samples from 12,337 patients were examined for antibodies to Mycoplasma pneumoniae at the Institute of Hygiene, University Hospital Vienna in the course of routine diagnosis. Antibody determination was performed by means of the microparticle agglutination assay Serodia Myco II. Overall, positive results (antibody titer > or = 1:40) were obtained in 2028 patients (16.4%). Age details were available for analysis in 2016 positive patients. Young children (< or = 9 y) who tested positive showed a geometric mean titer of 1:137.9 (95% confidence interval: 117.7-161.4). The geometric mean titers of positive patients decreased significantly with age (Spearman's correlation coefficient -0.20; p < 0.0001). Only 1/87 patients with serological evidence of M. pneumoniae infection aged > or = 70 y showed a titer of > or = 1:320. These data highlight the fact that, in the elderly, acute M. pneumoniae infection has to be considered in cases with slightly elevated antibody titers, which are usually referred to as borderline in children and young adults.