Mycoplasma Pneumoniae Infection Complicated by Lung Abscess, Pleural Effusion, Thrombocytopenia and Disseminated Intravascular Coagulation

Mycoplasma pneumoniae is a major pathogen of the respiratory tract in school age children and young adults. Pneumonia caused by M. pneumoniae has been classically described as a "walking pneumonia." It usually follows a benign course and the patient does not require hospitalization.1 Lung abscess associated with this pathogen is extremely rare and only four cases have been reported in the English literature.2-4 Here we report a patient with lung abscess associated with M. pneumoniae who experienced a protracted illness. Pleural effusion, thrombocytopenia and disseminated intravascular coagulation (DIC) occurred at the same time. Case report. A previously healthy 6-year-old girl was admitted to our hospital because of a 7-day history of cough and a 4-day history of fever. Dyspnea developed on the day before admission. She appeared acutely ill with respiratory distress. The body temperature was 39°C, pulse rate 120 beats/min and respiratory rate 50/min. Rales and rhonchi were present in both lung fields. Dullness to percussion, decrease in breath sound and friction rub were noted over the right lower lung field. The hemoglobin was 11.8 mg/dl, the white blood cell count was 10 200/mm3 with 91% neutrophils and 9% lymphocytes and the platelet count was 96 000/mm3. Aspartate aminotransferase was 178 IU/l and alanine aminotransferase was 50 IU/l. The sedimentation rate was 47 mm/h and the C-reactive protein concentration was 51.3 mg/dl (normal range, <0.6 mg/dl). Chest radiography showed consolidation with pleural effusion over the right lung and increased infiltration over the left lung. Diagnostic thoracocentesis and chest tube insertion were performed. The pleural fluid was yellow and not turbid. Analysis of pleural fluid showed: white blood cells 2800/mm3, red blood cells 207/mm3, protein 3600 mg/dl, glucose 112 mg/dl and lactate dehydrogenase 2149 units/l. No organisms were seen on Gram- and acid fast-stained smears. Vancomycin and cefotaxime were prescribed after appropriate cultures were taken. There was no improvement in this patient's condition. Spiking high fever and pleural effusion persisted for 2 weeks. Cultures for bacteria, Mycobacterium tuberculosis, fungi and viruses were all negative. Thrombocytopenia worsened and DIC was noted. The platelet count dropped to 32 000/mm3, prothrombin time was 2.2 times INR (international ratio) and partial thromboplastin time was 45.8 s. Computerized tomography of chest revealed consolidation of the right lung with abscess formation and moderate amount of pleural effusion over the right lung (Fig. 1). We performed a lung biopsy and sent the tissue for culture. Cultures for bacteria, Mycobacterium tuberculosis, fungi and viruses were negative. Serology for other infections were checked at this point. The cold hemagglutinin titer was 1:128 and the complement-fixation titer for M. pneumoniae was 1:1280. The previous antibiotics were discontinued and the patient was treated with erythromycin (40 mg/kg/day) for 3 weeks as well as vigorous postural drainage. The fever subsided 3 days after the initiation of erythromycin. Follow-up radiologic studies showed complete resolution of the abscess and pleural effusion. The cold hemagglutinin titer was 1:8 and complement-fixation titer for M. pneumoniae was 1:160 2 months after discharge.Fig. 1: Computerized tomography of chest showed consolidation of right lung with abscess formation.Discussion.M. pneumoniae pneumonia is usually a benign illness, and respiratory complications and extrapulmonary manifestations occur rarely. Most patients are treated as outpatients.1 Our patient had a protracted illness and was hospitalized for 4 weeks. Fever and toxic signs persisted for >2 weeks. Although no pathognomonic features are reported to be associated with M. pneumoniae pneumonia,5-7 the most common presentations of M. pneumoniae pneumonia in chest radiography are bronchopneumonia, platelike atelectasis, nodular infiltration and hilar adenopathy.8 Pleural effusion is not a common feature of M. pneumoniae, and when it occurs there is usually a small amount of effusion which does not require chest tube insertion.7, 9 Our patient had a large pleural effusion requiring chest tube insertion for >2 weeks. It is common to have lung abscess as a feature of pneumonia caused by Gram-negative bacteria such as Klebsiella pneumoniae, Bacteroides and Gram-positive cocci such as Staphylococcus aureus and elements of normal flora of upper respiratory tract. A lung abscess associated with laboratoryconfirmed M. pneumoniae infection is extremely rare. There have been only four cases reported in the English language literature.2-4 In 1972 Lewis and Sheptin2 described a 24-year-old man with bilateral pulmonary infiltrates, a massive left pleural effusion and a lung abscess. The bacterial cultures of pleural fluid were negative and the chest roentgenogram showed clearing within 5 weeks of initiation of tetracycline therapy. Siegler3 reported 2 cases and De Vos et al.4 reported one case of lung abscess in adult young males associated with M. pneumoniae pneumonia. Laboratory diagnosis of M. pneumoniae pneumonia depends on isolation of the organism by culture or serologic methods.10 Culture of the organism is difficult, requires 7 to 10 days and is outside the scope of the routine diagnostic laboratory. A >4-fold rise of complement-fixing antibody in paired sera is confirmation of infection. However, a rising titer is not always possible to show because the rise has frequently taken place before the patient is seen.5 Cold agglutinin are usually but not invariably raised. In combination with a high anti-mycoplasmal antibody titer, a cold agglutinin titer of 1:64 is diagnostic. The diagnosis of M. pneumoniae infection in our patient was made on clinical and serologic grounds. It was supported by a cold agglutinin titer of 1:128, complement-fixation titer of >1:1280, negative findings on Gram- and acid fast-stained smears and cultures of pleural fluid and biopsied lung tissues. The extrapulmonary manifestations of M. pneumoniae pneumonia including hematologic, gastrointestinal, musculoskeletal, dermatologic and neurologic complications are not common, with cases described as single reports or small series.11 The most frequent extrapulmonary manifestations are hematologic and hemolytic anemia is the most commonly reported, associated with IgM anti-I antibody (i.e. cold agglutinin). Our patient had thrombocytopenia and DIC rather than hemolytic anemia. DIC has been associated with M. pneumoniae infection in a reported few cases.12-14 The cause of DIC was unknown. Thrombocytopenia, although a common feature in many bacterial and viral infection, is an unusual manifestation of M. pneumoniae pneumonia.15-17 Although it could be secondary to DIC our patient had thrombocytopenia before development of DIC. Both of the hematologic complications resolved after treatment of erythromycin. In conclusion lung abscess, although rare, can be a possible manifestation of M. pneumoniae pneumonia. When a physician encounters a patient with unusual presentation of pneumonia and extrapulmonary manifestation, M. pneumoniae should be considered. Chen-Chia Chiou, M.D. Yung-Ching Liu, M.D. Hsi-Hsun Lin, M.D. Kai-Sheng Hsieh, M.D. Department of Pediatrics and Microbiology Laboratory; Veterans General Hospital-Kaohsiung; Kaohsiung, Taiwan