Role of erythromycin for treatment of incipient chronic lung disease in preterm infants colonised with Ureaplasma urealyticum

Antibiotics and Antifungals in Neonatal Intensive Care Units: A Review

The incidence of infections is higher in the neonatal period than at any time of life. The basic treatment of infants with infection has not changed substantially over the last years. Antibiotics (with or without supportive care) are one of the most valuable resources in managing sick newborn babies. Early-onset (ascending or transplacental) or late-onset (hospital acquired) infections present different chronology, epidemiology, physiology and outcome. Some classes of antibiotics are frequently used in the neonatal period: penicillins, cephalosporins, aminoglycosides, glycopeptides, monobactams, carbapenems. Other classes of antibiotics (chloramphenicol, cotrimoxazole, macrolides, clindamycin, rifampicin and metronidazole) are rarely used. Due to emergence of resistant bacterial strains in Neonatal Intensive Care Units (NICU), other classes of antibiotics such as quinolones and linezolid will probably increase their therapeutic role in the future. Although new formulations have been developed for treatment of fungal infections in infants, amphotericin B remains first-line treatment for systemic Candida infection. Prophylactic antibiotic therapy is almost always undesirable. Challenges from pathogens and antibiotic resistance in the NICU may warrant modification of traditional antibiotic regimens. Knowledge of local flora and practical application of different antibiotic characteristics are key to an effective and safe utilization of antibiotics and antifungals in critical newborns admitted to the NICU, and especially in very low birth weight infants.

Maternal administration of erythromycin fails to eradicate intrauterine ureaplasma infection in an ovine model

Erythromycin is the standard antibiotic used for treatment of infection with Ureaplasma spp. during pregnancy; however, maternally administered erythromycin may be ineffective at eliminating intra-amniotic ureaplasma infections. We examined whether erythromycin would eradicate intra-amniotic ureaplasma infections in pregnant sheep. At Gestational Day (GD) 50 (term, GD 150), pregnant ewes received intra-amniotic injections of erythromycin-sensitive Ureaplasma parvum serovar 3 (n = 16) or 10B medium (n = 16). At GD 100, amniocentesis was performed; five fetal losses (ureaplasma group, n = 4; 10B group, n = 1) had occurred by this time. Remaining ewes were allocated into treatment subgroups: medium only (n = 7), medium and erythromycin (n = 8), ureaplasma only (Up; n = 6), or ureaplasma and erythromycin (Up/E; n = 6). Erythromycin was administered intramuscularly (500 mg) every 8 h for 4 days (GDs 100-104). Amniotic fluid samples were collected at GD 105. At GD 125, preterm fetuses were surgically delivered, and specimens were collected for culture and histology. Erythromycin was quantified in amniotic fluid by liquid chromatography-mass spectrometry. Ureaplasmas were isolated from the amniotic fluid, chorioamnion, and fetal lung of animals from the Up and Up/E groups, however, the numbers of U. parvum recovered were not different between these groups. Inflammation in the chorioamnion, cord, and fetal lung was increased in ureaplasma-exposed animals compared to controls but was not different between the Up and Up/E groups. Erythromycin was detected in amniotic fluid samples, although concentrations were low (<10-76 ng/ml). This study demonstrates that maternally administered erythromycin does not eradicate chronic, intra-amniotic ureaplasma infections or improve fetal outcomes in an ovine model, potentially because of the poor placental passage of erythromycin.

Ureaplasma infection and neonatal lung disease

Infection with the ureaplasmas may occur in utero or perinatally in prematurely born infants. For some infants, infection with these organisms triggers a vigorous pro-inflammatory response in the lungs and increases the risk of developing bronchopulmonary dysplasia (BPD). At present, there is insufficient evidence from clinical trials to determine whether antibiotic treatment of Ureaplasma has any influence on the development of BPD and its comorbidities. Future investigation in the context of well-designed, adequately powered controlled clinical trials should focus on determining whether treatment of ureaplasmal infection lessens lung inflammation, decreases rates of BPD, and improves long-term, neurodevelopmental outcome.

Critical appraisal of the role of Ureaplasma in the development of bronchopulmonary dysplasia with metaanalytic techniques

BACKGROUND

Controversy exists over whether or not Ureaplasma colonization or infection of the respiratory tract contributes to the development of bronchopulmonary dysplasia (BPD). Because BPD is a major cause of morbidity and mortality in preterm infants and a potential therapeutic intervention with antimicrobials is possible, we sought to evaluate and critique the current medical literature and to document the reported association between Ureaplasma and BPD.

METHODS

We analyzed all peer-reviewed articles and previous reviews including cross-references that reported Ureaplasma respiratory tract colonization or infection and development of BPD in neonates published from January 1966 to December 2004. Inclusion criteria included a cohort limited to all neonatal intensive care unit admissions or all colonized infants, articles that did not define a numerator and a denominator for BPD and Ureaplasma or that included patients from other reports were excluded from the analysis. We evaluated BPD at 28 postnatal days (BPD28) or 36 weeks post-menstrual age (BPD36).

RESULTS

Twenty-three studies with an aggregate of 2216 infants reported BPD28, and 8 studies with 751 infants reported BPD36. Although there was significant association between Ureaplasma colonization and both BPD28 and BPD36, there was substantial heterogeneity (Q test statistic, P < 0.01). We therefore focused on describing the study characteristics associated with an increased relative proportion of BPD. The greatest contribution to effect was from the studies enrolling fewer than 100 infants.

CONCLUSION

Ureaplasma colonization is associated with higher reported rates of BPD, but the greatest reported effect is seen in small studies; reporting bias may be partially responsible for this effect.

Erythromycin for the prevention of chronic lung disease in intubated preterm infants at risk for, or colonized or infected with Ureaplasma urealyticum

BACKGROUND

Controversy exists over whether or not Ureaplasma urealyticum colonization or infection of the respiratory tract contributes to the severity of chronic lung disease (CLD), a major cause of morbidity and mortality in preterm infants.

OBJECTIVES

To evaluate the efficacy and safety of prophylactic or therapeutic erythromycin in preventing chronic lung disease in intubated preterm infants with unknown U. urealyticum status or proven positivity.

SEARCH STRATEGY

Searches were done of MEDLINE (1966-June 9, 2003), EMBASE (1980-May 5, 2003), The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2002), previous reviews including cross-references, and abstracts of conference proceedings (Pediatric Academic Societies 2000-2003, American Thoracic Society 2001-2003). There were no language restrictions. Expert informants were contacted.

SELECTION CRITERIA

Randomized or quasi-randomized studies comparing either prophylactic or therapeutic administration of oral or intravenous erythromycin (regardless of dose and duration) versus no treatment or placebo among intubated preterm infants <37 weeks and <2500 grams with either unknown U. urealyticum status or proven positivity by culture or polymerase chain reaction.

DATA COLLECTION AND ANALYSIS

Data were extracted by all of the authors independently and differences were resolved by consensus. Treatment effects for categorical outcomes were expressed as relative risk, with 95% confidence intervals.

MAIN RESULTS

Two small controlled studies, both involving intubated babies <30 weeks gestation, were eligible for inclusion. Lyon 1998 tested prophylactic erythromycin in babies whose U. urealyticum status was unknown at the time of initiation of treatment. Jonsson 1998 tested erythromycin in babies known to be culture positive for U. urealyticum. Neither trial showed a statistically significant effect of erythromycin on CLD, death or the combined outcome CLD or death. Because the two studies differed importantly in their design, the results were not combined in meta-analyses. No adverse effects of a 7-10 day course of erythromycin were reported in either study.

REVIEWER'S CONCLUSIONS

Current evidence does not demonstrate a reduction in CLD/death when intubated preterm infants are treated with erythromycin prophylactically before U. urealyticum culture/PCR results are known or when Ureaplasma colonized, intubated preterm infants are treated with erythromycin. However, a true benefit could easily have been missed with the small sample sizes in the two eligible studies. The studies were greatly underpowered to detect uncommon adverse effects such as pyloric stenosis. Additional controlled trials are required to determine whether antibiotic therapy of Ureaplasma reduces CLD and/or death in intubated preterm infants.