Relationship between bronchoalveolar lavage mycoplasma load and clinical characteristics in children with Mycoplasma pneumoniae pneumonia / 中华儿科杂志

<p><b>OBJECTIVE</b>Mycoplasma pneumoniae (MP) is an important pathogen for community-acquired pneumonia in children. MP infection was considered to be self-limited, but many severe refractory MP pneumonia cases have been reported in recent years. The reason for variation in severity of MP pneumonia remains unclear. MP virulence including drug-resistance and host immunologic function are important influencing factors. The present study aimed to clarify relationship between local MP load and severity of MP pneumonia.</p><p><b>METHOD</b>MP DNA was quantitatively detected by fluorescent real-time PCR in bronchoalveolar lavage fluid (BALF) from 77 children with MP pneumonia. They were classified into groups of low MP load ( < 10(3)/ml, n = 14) , moderate MP load (10(3)-10(6)/ml, n = 22) and high MP load ( > 10(6)/ml, n = 41) . Clinical symptoms, main laboratory and imaging results of children among the three groups were compared.</p><p><b>RESULT</b>When compared with low load group and moderate load group, high load group had longer fever duration (7 d, 10 d vs. 12 d) , longer time to normalization of temperature with macrolide administration (4 d, 8 d vs. 10 d) , more patients with high fever (50.0%, 68.2% vs. 87.8%) and longer duration of fever than 10 d (35.7%, 50.0% vs. 73.2%).Statistically significant difference existed in CRP among the three groups (1.0 mg/L, 11.5 mg/L, 34 mg/L). Large field of consolidation or atelectasis were found in 58.5% of high load patients, much higher than 22.7% in moderate load and 14.3% in low load patients. Bilateral or massive pleural effusion was not found in low load group, while in moderate load and high load group, they were 13.6% and 24.4%. However, no significant difference was found in symptoms and main laboratory and imaging results among different age groups in high load patients.</p><p><b>CONCLUSION</b>There is a close relationship between MP load in BALF and clinical characteristics in children with MP pneumonia. Those with high MP load have a more severe process.</p>

Mixed infections in children with Mycoplasma pneumoniae pneumonia / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the incidence and clinical features of mixed infections in children with Mycoplasma pneumoniae (MP) pneumonia.</p><p><b>METHOD</b>A total of 201 cases diagnosed as MP pneumonia were investigated for mixed infections by sputum bacterial culture, respiratory virus antigen detection and serum Chlamydia pneumoniae antibody test. For those with the indications for bronchoscopy, we also did bronchoalveolar lavage and lavage bacterial culture.</p><p><b>RESULT</b>A high incidence (103/201, 51.2%) of mixed infections in children with MP pneumonia was revealed. The most frequent co-infected pathogen was Chlamydia pneumoniae (52, 25.9%), followed by viruses (29, 14.4%), and bacteria (22, 10.9%). Among viruses, respiratory syncytial virus was the most common (17, 8.5%), followed by adenovirus (6, 3.0%), parainfluenza virus type III (4, 2.0%) and influenza virus type B (2, 1.0%). Sputum bacterial culture was positive in 14/201 (7.0%) cases, Streptococcus pneumonia being most common (6, 3.0%). BALF culture yielded positive results in 11.6% (8/69), Streptococcus pneumonia was also common (5, 7.3%). Among 29 cases with MP and virus coinfection, 26 were younger than 3 years (89.7%), while for MP and Chlamydia pneumoniae coinfection, most of them were older than 3 years (40/52, 76.9%). Compared with non-mixed infections, those with mixed infections had longer fever duration (24.5% and 40.8% longer than 10 d), more frequently developed pleural effusion (11.2%, 23.3%) and large area of shadow in chest imaging (35.7%, 51.5%). White blood cell [(14.28 ± 4.99) × 10(9)/L], C-reactive protein (CRP) [69(32.5 - 99.5) mg/L] and neutrophil ratio in BALF [0.86 (0.63 - 0.91)] were much higher in children with mixed bacterial infections than that in non-mixed infections [(9.06 ± 3.47) × 10(9)/L, 3 (0 - 31.0) mg/L, 0.44 (0.03 - 0.88)]. But no significant difference was found in peripheral blood neutrophil proportion between mixed bacterial infections (0.38 ± 0.25) and non-mixed infections (0.51 ± 0.19).</p><p><b>CONCLUSION</b>More than half of cases with MP pneumonia had mixed infections, most commonly caused by Chlamydia pneumonia followed by viruses. The incidence of mixed infections with bacteria was low. Mixed infections with virus were more common in young children, while mixed infection with Chlamydia pneumoniae was more common in older ones. Bacterial infections should be paid more attention, especially those caused by Streptococcus pneumoniae, for those with high peripheral white blood cell counts, high CRP levels and high proportion of neutrophils in BALF.</p>