Mycoplasma and Acute Chest Syndrome in Sickle Cell Disease
Abstract & Commentary
Synopsis: A prospective study of 671 episodes of acute chest syndrome in 538 patients with sickle cell anemia found that 51 (9%) had serologic evidence of Mycoplasma pneumoniae infection, including 12% of episodes in children < 5 years of age. Mycoplasma hominis was cultured in 10 episodes.
Source: Neumary L, et al. Mycoplasma disease and acute chest syndrome in sickle cell disease. Pediatrics. 2003;112: 87-95.
A prospective study of acute chest syndrome was performed at 30 centers of children with sickle cell disease (hemoglobin SS, hemoglobin SC, or hemoglobin SB). Acute chest syndrome was defined as a new pulmonary infiltrate (involving at least 1 complete segment consistent with alveolar consolidation, excluding transient atelectasis) associated with chest pain, fever > 38.5°C, tachypnea, wheezing, or cough. The study included a total of 671 episodes among 538 hospitalized patients enrolled from March 1993 through March 1997.
Paired serologies from 598 episodes in 484 patients documented Mycoplasma pneumoniae infection in 51 episodes (9%). Infection with M pneumoniae was determined by a 4-fold rise in IgG antibody titers between acute and convalescent sera (31 patients), or by a high IgG titer (> 1024) in paired serologies and detectable IgM antibodies (20 patients). There were no cases of recurrent infection documented. Of 555 episodes with appropriate samples, cultures for M pneumoniae were positive in 2 episodes. In the other 10 episodes, Mycoplasma hominis was identified by culture, with serologies that were not consistent with acute M pneumoniae infection. A total of 9 patients with M pneumoniae had evidence of another pathogen including rhinovirus, respiratory syncytial virus, Steptococcus pneumoniae, and Haemophilus influenzae. The incidence of M pneumoniae was higher in younger patients—12% of 112 episodes in patients < 5 years, 14% of 181 episodes in patients 10-14.9 years, and only 3% of the 207 episodes in children > 15 years of age.
At the time of diagnosis, 98% of all patients had fever, 78% had cough, and 51% were tachypneic. During hospitalization, more than half of these patients developed multilobar pneumonia, 84% required supplemental oxygen, 82% required transfusion, 6% required assisted ventilation, and 78% were administered bronchodilators. The average hospital stay was 10 days.
The average age of the 10 patients with M hominis was higher than those with M pneumoniae (18.6 years vs 9.7 years; P = .004). The rate of vaso-occlusive crisis was higher (60% vs 39%,) and the duration of hospitalization was longer (13.1 days vs 9.8 days), but these were not statistically significant.
Comment by Hal B. Jenson, MD
This study found that M pneumoniae, and less often M hominis, is commonly associated with acute chest syndrome in patients with sickle cell disease, including very young children. The incidence of M pneumoniae in children younger than 5 years (12%) was similar to that in 5- to 10-year olds (14%). Patients with acute chest syndrome, including children younger than 5 years, should be treated with a broad-spectrum antibiotic regimen that includes a macrolide antibiotic. A common regimen is a broad-spectrum cephalosporin and either erythromycin or azithromycin. Mycoplasma also contributes to bronchial hyper-reactivity, as evidenced in 36% of these patients, who had wheezing during their hospitalization, and bronchodilator therapy is usually indicated. Early administration of leukocyte-depleted, matched simple transfusions are indicated in the presence of significant anemia, multilobar pneumonia, any signs of respiratory distress on oxygen, and those at risk for complications.
Dr. Jenson is Chair, Department of Pediatrics, Director, Center for Pediatric Research, Eastern Virginia Medical School and Children's Hospital of the King's Daughters, Norfolk, VA.