STUDIES ON EATON PPLO PNEUMONIA

The first atypical pneumonia: the history of the discovery of Mycoplasma pneumoniae

The subject of atypical pneumonias is of great medical and historical interest to modern physicians. Although these diseases have no doubt affected humans throughout our history, it is not until the mid-twentieth century that physicians first began to differentiate certain atypical pulmonary infectious processes from typical pneumonia. Physicians at the time were unclear as to the precise etiology of these infections. As time progressed and study of these organisms continued, physicians were better able to identify the causative agent and devise tests with which to detect the disease. This article focuses on the description and ultimate identification of Mycoplasma pneumoniae.

Carditis associated with mycoplasma pneumoniae infection

Among 560 patients with serologically confirmed Mycoplasma pneumoniae infection, 25 (4.5%) had carditis (19 perimyocarditis, 6 pericarditis). During the acute phase 9 patients required intensive care. After an average of 16 months follow-up 11 patients with no previous signs of heart disease still had cardiac symptoms or signs. Thus carditis associated with M. pneumoniae infection is a serious disease, having cardiac sequelae more often than has hitherto been supposed. The pathogenesis of the carditis associated with M. pneumoniae infection is discussed, including the possibility that in some cases the elevated titre in the complement fixation test is non-specific. A summary is given of the 33 cases previously presented in the literature.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."

Mycoplasma pneumoniae infections and Stevens-Johnson syndrome. Report of eight cases and review of the literature

On the basis of a literature review and eight cases of our own, we analyzed 37 cases of Mycoplasma pneumoniae (MP) infection and Stevens-Johnson syndrome (SJS). Our clinical and laboratory findings do not differ from those reported in the literature for MP infection with no exanthem or for SJS of various etiologies. Eighty percent of the children presented with symptoms of upper respiratory tract infection (URTI) (cough, fever, sore throat, malaise, headache), with a mean of 10 days (range 1 to 30) before skin rash broke out. Skin manifestations occurred in 94.2% of the patients after 3 to 21 days (mean 10.3 days) of fever. The exanthem, composed predominantly of maculopapular and vesicular, was distributed chiefly on the trunk and extremities and lasted less than 14 days in 87.8% of the patients. Stomatitis was observed in 91.6% of the patients and conjunctivitis in 50%. No consistent pattern seems to emerge by which one could predict the existence of MP infection causing SJS. The complications of SJS associated with MP seem less frequent (2.7%) and much less severe than in cases where SJS arises from other reported causes. Because coincidence cannot be excluded from the assessments of the degree and rate of improvement for the few patients treated with corticosteroid, from the low frequency of complications, and from the mortality rate of zero in this series of patients, the use of corticosteroids for SJS associated with MP infection is questionable.

Age-related prevalence of complement-fixing antibody to Mycoplasma pneumoniae during an 8-year period

We determined the age-related prevalence of complement-fixing antibody to Mycoplasma pneumoniae from the computerized laboratory results of our routine diagnostic department. The material consisted of about 58,000 sera from an 8-year period, 1971 to 1978. Among children less than 1 month old, the frequency of complement-fixing antibody of titers greater than or equal to 8 was low (23%), and no decrease representing loss of maternal antibody was seen thereafter. An unexpectedly early increase in the antibody prevalence up to 62% was seen by 6 months of age. The frequency of antibody was high among young children from the age of 4 months, in whom symptomatic infection due to M. pneumoniae is rare. The frequency of higher titers (greater than or equal to 32) and the geometric mean titer increased more slowly, coinciding with the known age distribution of symptomatic M. pneumoniae disease; the frequency of high titers and the geometric mean titer peaked at the age of 7 to 10 years. Two explanations for the high frequency of complement-fixing antibody to M. pneumoniae in young children are discussed. It may be due to an asymptomatic infection caused by M. pneumoniae or to a nonspecific stimulus by lipids of other organisms, plants, or tissues leading to production of antibodies crossreacting with M. pneumoniae, or it may be due to both of the above. During the study, two extensive epidemics due to M. pneumoniae occurred in Finland, but the prevalence of complement-fixing antibody bore no correlation with these peaks of occurrence.

Clinical and laboratory manifestations in patients with serological evidence of Mycoplasma pneumoniae infection

139 cases of Mycoplasma pneumoniae infection (serological diagnosis) were treated at Aurora Hospital, Helsinki, between January 1975 and August 1977. In 123 patients the main diagnosis was respiratory infection; 114 of these had pneumonia. The frequency of complications was high: 8 patients had neurologic, 6 cardiac and 5 joint symptoms. Although a significant rise in titre of complement-fixing antibodies to M. pneumoniae was required, the low titre level in some patients who had manifestations less frequently associated with M. pneumoniae infection may suggest nonspecific reactions. Nearly half of the patients in this study had plasmocytosis in the peripheral blood suggesting a strong antibody response. This might be connected with some serological reactions detected in association with M. pneumoniae infections.

Mycoplasma pneumoniae infections in children

Details are given of all serologically confirmed Mycoplasma pneumoniae infections in children referred to Bristol hospitals during an epidemic lasting 18 months. 44 children, many below school age, had lower respiratory infections. The majority had cough and malaise which had failed to respond to antibiotics given before referral. Chest x-rays showed no pathognomonic features: segmental or patchy consolidation was common; 3 cases of lobar consolidation. Cold agglutinins were raised in 9 out of 12 cases. In the majority of cases the total leucocyte count was normal and the absolute neutrophil count raised. Mean duration of symptoms was 4.2 weeks (range 1-16). Treatment with erythromycin or tetracycline appeared to have little effect in most cases. Seven nonrespiratory manifestations were seen in 6 children. These were meningitis (2 cases), Stevens-Johnson syndrome (4 cases, 1 case complicated by toxic epidermal necrolysis), and acute haemolytic anaemia (1 case).

The treatment of Mycoplasma pneumoniae infections

Apart from several family outbreaks (Watson, 1961), I have encountered two widespread epidemics, each involving about 100 patients in a rural general practice in Surrey, one lasting about 9 months in 1963/64 and the second about 7 months in 1974/75 (Watson, 1967). Twenty-five unselected families in 1963/64 and 31 comparable families in 1974/75 were studied in greater detail than the rest.

This paper presents a comparison between the results of treatment in these two groups. Tetracycline or Oxytetracycline 250 mg. four times a day (q.d.s.) was the usual adult treatment in the first epidemic, with proportionately less of the Oxytetracycline 125 mg. syrup for children under 10 years. In the second epidemic adults were given erythromycin stearate 250 mg. q.d.s., while children received the ethyl succinate suspension q.d.s. in age-related doses. Treatment in both epidemics was usually continued as long as signs in the chest or coughing persisted.

The conclusion was that an erythromycin rather than a tetracycline is the drug of choice for a patient with an acute febrile chest infection by M. pneumoniae because (a) fever and coughing were reduced more quickly, (b) relapses were less frequent, (c) lethargy and slow convalescence were prevented or cleared in a few days, and (d) infectiousness was apparently reduced by erythromycin treatment.

The radiographic patterns of acute mycoplasma pneumonitis

Twenty-two cases of serologically proven pulmonary mycoplasma infection have been reviewed. All showed abnormality on plain chest radiographs. A definitive diagnosis could not be made on initial or individual films. However, studies of sequential films enabled diagnostic patterns to be distinguished.

The incidence of Mycoplasma pneumoniae infections in Denmark over the past seventeen years: a review

The variations in the incidence of Mycoplasma pneumoniae infections in Denmark over a period of 17 years could be demonstrated in the central serological laboratory which serves the whole of the population. This observation was made possible for the first and major part of this study by testing cold agglutinin (CA) positive sera, which had been kept frozen sine 1958, for antibodies to M.pneumoniae. The second part of the study is based upon results from routine tests for CA and M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae antibodies on all samples which we receive. A statistical analysis of the total material indicates that four epidemics of M.pneumoniae infection had taken place from January 1958 to December 1974 and that these epidemics occurred at regular four and a half year intervals. By a follow-up of the study a fifth epidemic was demonstrated during the first eight months of 1975 which broke the regular periodicity by appearing two years earlier than expected. The consequences of including only CA positive sera in this study was investigated. Antibodies to M.pneumoniae were measured by either an indirect immunofluorescence test, an indirect haemagglutination test or a complement fixation test. The observed difference in sensitivity of these tests is discussed in relationship to a possible influence on the overall incidence.

The protean manifestations of Mycoplasma pneumoniae infection in adults

Mycoplasma pneumoniae is a well recognized respiratory pathogen in children and young adults. In addition, M. pneumoniae infections may also involve other organ systems. Reviewed here are the various clinical syndromes in adults caused by this infectious agent, with emphasis on those which have recently been seen at The New York Hospital. Two previously unreported manifestations of M. pneumoniae infection, cranial nerve mononeuropathy and hepatitis, are described, and the laboratory methods for diagnosis are discussed.

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Mycoplasma pneumoniae. One year's experience in an urban practice

During 1967, 37 patients in an urban general practice were diagnosed as having Mycoplasma pneumoniae infections giving a minimum attack rate of 1.1 per cent. Their varied clinical picture is described, along with the radiographic and haematological findings. Data relating to family infection is presented and the importance of the early school age child in relation to the spread of this infection is stressed. It is suggested that this infection is a ‘general practice illness’ with a low hospital component.