Ureaplasma urealyticum and pulmonary outcome in a neonatal intensive care population

Association between Ureaplasma urealyticum colonization and bronchopulmonary dysplasia in preterm infants: a systematic review and meta-analysis

Background

Bronchopulmonary dysplasia (BPD) is the most prevalent chronic lung disease in preterm infants. Studies have shown that Ureaplasma urealyticum (UU) infection is linked to its pathogenesis. However, it remains controversial whether UU colonization in preterm infants increases the risk of developing BPD.

Objective

This study aimed to conduct a systematic review and meta-analysis to summarize the correlation between UU and BPD.

Methods

We searched PubMed, Embase, the Cochrane Library, Web of Science, Wanfang Database, Chinese National Knowledge Infrastructure Database, Chinese Science and Technique Journal Database, and the China Biology Medicine disc from their inception to March 15, 2024. We included cohort and case-control studies investigating the association between UU infections and BPD in preterm infants, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Newcastle-Ottawa Scale was used for quality assessment. The outcome was defined as the continued need for oxygen or respiratory support at 28 days after birth (BPD28) or at 36 weeks postmenstrual age (BPD36). Considering the potential publication bias in observational studies, we used a random-effects meta-analysis model, assessed heterogeneity (I2), performed subgroup analyses, evaluated publication bias, and graded the quality of evidence.

Results

The meta-analysis included 36 cohort studies encompassing 5,991 participants. Among these, 20 reported on BPD28, 13 on BPD36, and 3 on both. The results indicated a significant association between UU colonization and BPD28 (odds ratio (OR): 2.26, 95% confidence interval (CI): 1.78-2.85, P < 0.00001, 23 studies, very low certainty of evidence) and BPD36 (OR: 2.13, 95% CI: 1.47-3.07, P < 0.0001, 16 studies, very low certainty of evidence).

Conclusion

There is a correlation between UU colonization and the development of BPD in preterm infants. Future research should prioritize well-designed, large-scale, high-quality randomized controlled trials (RCTs) to comprehensively assess the risk of BPD in neonates following UU infection and to provide stronger evidence for clinical screening and prevention strategies to improve the prognosis of affected newborns.

Systematic Review Registration

https://www.crd.york.ac.uk/, identifier (CRD42024524846).

Epidemiological and Clinical Characteristics of Neonatal Ureaplasma urealyticum Infection

Purpose

To understand the epidemiology and clinical features of Ureaplasma urealyticum (UU) infection in hospitalized neonates due to vertical transmission from mother to child.

Methods

Respiratory secretions were collected from neonates hospitalized in the neonatology department of the Maternal and Child Health Hospital of Hubei Province from July 2020 to June 2022, and PCR was used to detect UU-DNA in respiratory secretions. The neonates were divided into UU-positive and UU-negative groups, the epidemiological and clinical characteristics of two groups, were statistically analyzed.

Results

A total of 7257 hospitalized neonates were included in this study, of whom 561 were UU positive and 6696 were UU negative, with a UU detection rate of 7.73%. The detection rate among female neonates was higher than male neonates, and the highest detection rate was found in the period from 1-7 days after birth; the detection rate was highest in spring and fall, and the lowest in winter, but the overall difference was not statistically significant (P>0.05). Compared with the UU-negative group, neonates in the UU-positive group were more likely to be preterm, have a lower birth weight, be delivered vaginally, and have maternal preterm rupture of membranes. In addition, neonates in the UU-positive group were more likely to be co-infected with pathogens and to have complications related to UU infections, which were all statistically significant (P<0.05).

Conclusion

Neonatal UU infections are detected more frequently in female infants, with the highest detection rate occurring in 1-7 days after birth, and the most prevalent periods for infection being spring and fall. Vaginal delivery and premature rupture of membranes may lead to an increased risk of vertical UU transmission from mother to child, and UU infection is strongly associated with preterm labor, low birth weight, pathogen co-infection, and related complications.

Association of Ureaplasma infection pattern and azithromycin treatment effect with bronchopulmonary dysplasia in Ureaplasma positive infants: a cohort study

BACKGROUND

It is unclear whether Ureaplasma-associated pneumonia and azithromycin treatment affect the risk for bronchopulmonary dysplasia (BPD).

METHODS

A retrospective cohort study was performed in very low birth weight (VLBW) infants who tested positive for Ureaplasma within 72 h after birth in a tertiary unit. Chest X-ray (CXR) and laboratory test were performed before and after azithromycin treatment. Multivariate logistic regression analysis was used to identify the independent association between BPD and Ureaplasma-associated pneumonia, as well as BPD and effective azithromycin treatment.

RESULTS

A total of 118 infants were included in the current study, of whom 36 developed BPD (defined as supplemental oxygen needed at postmenstrual age 36 weeks or discharge). The rate of BPD was significantly higher in infants with Ureaplasma-associated pneumonia (44.6%) compared to infants with Ureaplasma colonization (17.7%, P = 0.002). After adjusting for confounders, an effective azithromycin treatment was significantly associated with reduced risk of BPD [odd ratio (OR) 0.011; 95% confidence interval (CI): 0.000-0.250), whereas Ureaplasma-associated pneumonia was not significantly associated with BPD (OR 1.835; 95% CI: 0.548-6.147).

CONCLUSION

Effective Azithromycin treatment in Ureaplasma positive VLBW infants was associated with a reduced risk of BPD.

Lethal Neonatal Respiratory Failure by Perinatal Transmission of Ureaplasma Parvum after Maternal PPROM

A primiparous pregnant woman was admitted due to preterm premature rupture of membranes (PPROM) at 27+0 week of gestational age (WGA). Conventional vaginal microbiological analysis had no pathological finding. Management decisions based on national guidelines included antenatal corticoids, tocolytics and antibiotics. Unstoppable efforts of preterm labor in 28+0 WGA and supposed amniotic infection syndrome necessitated emergency cesarean section. The preterm infant underwent NICU therapy, developed an early-onset neonatal sepsis and therapy-refractory pulmonary insufficiency with consecutive right heart failure, resulting in death on the 36^th day of life. Microbiota analyses by 16Sr DNA sequencing was performed from maternal vaginal swabs and from neonatal pharyngeal swabs. Maternal antibiotic treatment resulted in depletion of physiological vaginal colonization with Lactobacillus crispatus. Ureaplasma parvum became the dominant vaginal microorganism at delivery and was detected in high relative abundance in the neonatal specimen. Progressive radiological air-space changes and interstitial pathologies associated with Ureaplasma infection (bronchopulmonary dysplasia type III) were seen early at the 3^rd and distinctly from 14^th day of life. This clearly demonstrates the need of vaginal colonization diagnostics in PPROM patients and awareness of the consecutive risks in the preterm. Vaginal microbiome analysis may allow individualized and targeted maternal and fetal diagnostic, prophylactic and therapeutic strategies to identify, protect and treat the high-risk neonates after PPROM.

Optimum Detection of Ureaplasma in Premature Infants

BACKGROUND

Ureaplasma spp. is a known risk factor for bronchopulmonary dysplasia in premature infants. Emerging research suggests treatment with azithromycin or clarithromycin in the first days of life (DOLs) reduces bronchopulmonary dysplasia in Ureaplasma spp. positive infants. Side effects of these antibiotics make it imperative to optimize reliable noninvasive screening procedures to identify infants who would benefit from treatment.

METHODS

The aim of this study was to determine the best site and time to screen for Ureaplasma spp. in 24- to 34-week premature infants. Oral, nasal, gastric and tracheal cultures were collected and placed immediately in 10B broth media. Polymerase chain reaction verified culture results and identified the Ureaplasma spp.

RESULTS

Cultures yielded a Ureaplasma spp. incidence of 80/168 = 47.6% [95% confidence interval (CI): 40-56]. Nasal cultures had greater sensitivity to detect Ureaplasma spp. than oral cultures (P = 0.008): however, a significant proportion of infants with Ureaplasma spp. would have been missed (12/79 = 15.2%, 95% CI: 8%-25%, P < 0.001) if oral cultures were not obtained. For all sites, the collection at DOL 7-10 were more likely to be positive than the collection at DOL 1-2: however, a significant proportion (5/77 = 6.5%, 95% CI: 2-15, P < 0.001) of infants with Ureaplasma spp. would have been missed if the DOL 1-2 cultures were not obtained.

CONCLUSIONS

For optimal Ureaplasma spp. detection in 24- to 34-week premature infants, cultures need to be taken both early and late in the first 10 DOLs both from nasal and oral secretions.

Role of Ureaplasma Respiratory Tract Colonization in Bronchopulmonary Dysplasia Pathogenesis: Current Concepts and Update

Respiratory tract colonization with the genital mycoplasma species Ureaplasma parvum and Ureaplasma urealyticum in preterm infants is a significant risk factor for bronchopulmonary dysplasia (BPD). Recent studies of the ureaplasmal genome, animal infection models, and human infants have provided a better understanding of specific virulence factors, pathogen-host interactions, and variability in genetic susceptibility that contribute to chronic infection, inflammation, and altered lung development. This review provides an update on the current evidence supporting a causal role of ureaplasma infection in BPD pathogenesis. The current status of antibiotic trials to prevent BPD in Ureaplasma-infected preterm infants is also reviewed.

Association between pulmonary ureaplasma colonization and bronchopulmonary dysplasia in preterm infants: updated systematic review and meta-analysis

BACKGROUND

Previous meta-analyses have reported a significant association between pulmonary colonization with Ureaplasma and development of bronchopulmonary dysplasia (BPD). However, because few studies reporting oxygen dependency at 36 weeks corrected gestation were previously available, we updated the systematic review and meta-analyses to evaluate the association between presence of pulmonary Ureaplasma and development of BPD.

METHODS

Five databases were searched for articles reporting the incidence of BPD at 36 weeks postmenstrual age (BPD36) and/or BPD at 28 days of life (BPD28) in Ureaplasma colonized and noncolonized groups. Pooled estimates were produced using random effects meta-analysis. Meta-regression was used to assess the influence of difference in gestational age between the Ureaplasma-positive and Ureaplasma-negative groups. The effects of potential sources of heterogeneity were also investigated.

RESULTS

Of 39 studies included, 8 reported BPD36, 22 reported BPD28 and 9 reported both. The quality of studies was assessed as moderate to good. There was a significant association between Ureaplasma and development of BPD36 (odds ratio = 2.22; 95% confidence intervals: 1.42-3.47) and BPD28 (odds ratio = 3.04; 95% confidence intervals: 2.41-3.83). Sample size influenced the odds ratio, but no significant association was noted between BPD28 rates and difference in gestational age between Ureaplasma colonized and noncolonized infants (P = 0.96).

CONCLUSIONS

Pulmonary colonization with Ureaplasma continues to be significantly associated with development of BPD in preterm infants at both 36 weeks postmenstrual age and at 28 days of life. This association at BPD28 persists regardless of difference in gestational age.

Association of Ureaplasma urealyticum colonization with development of bronchopulmonary dysplasia: a systemic review and meta-analysis

There is controversy regarding the roles of Ureaplasma urealyticum (U. urealyticum) colonization in the development of bronchopulmonary dysplasia (BPD). This study explored the association between U. urealyticum and bronchopulmonary dysplasia at 36 weeks post-menstrual age (BPD36). Studies published before December 31, 2013 were searched from Medline, Embase, Ovid, Web of Science, and Cochrane databases, with the terms "Ureaplasma urealyticum", "chronic lung disease", or "BPD36" used, and English language as a limit. The association between U. urealyticum colonization and BPD36 was analyzed with RevMan 4.2.10 software, using the odds ratio (OR) and relative risk (RR) for dichotomous variables. Out of the enrolled 81 studies, 11 investigated the BPD36 in total 1193 infants. Pooled studies showed no association between U. urealyticum colonization and subsequent development of BPD36, with the OR and RR being 1.03 (95% CI=0.78-1.37; P=0.84) and 1.01 (95% CI= 0.88-1.16, P=0.84), respectively. These findings indicated no association between U. urealyticum colonization and the development of BPD36.

Ureaplasma species: role in neonatal morbidities and outcomes

The genital mycoplasma species, Ureaplasma parvum and Ureaplasma urealyticum are the most common organisms isolated from infected amniotic fluid and placentas, and they contribute to adverse pregnancy outcomes including preterm birth and neonatal morbidities. In our institution, almost half of the preterm infants of less than 32 weeks gestation are Ureaplasma-positive in one or more compartment (respiratory, blood and/or cerebrospinal fluid), indicating that these organisms are the most common pathogens affecting this population. This review will focus on the compelling epidemiological and experimental evidence linking perinatal Ureaplasma species exposure to important morbidities of prematurity, such as bronchopulmonary dysplasia, intraventricular haemorrhage and necrotising enterocolitis.

Ureaplasma and BPD

Ureaplasma is an organism with low virulence and is a commensal of the lower genito-urinary tract in females. From here, it can gain entry in the amniotic fluid to cause inflammation in the amniotic compartment during pregnancy. Ureaplasma spp. are the most common organisms isolated from women with chorioamnionitis. Ureaplasma spp. are associated with increased risk for preterm labor and morbidity in the preterm neonate. However, there is some controversy regarding the importance of Ureaplasma in the pathogenesis of bronchopulmonary dysplasia (BPD). This article will review the microbiology of Ureaplasma, host innate immune responses, and the pathology of lung injury in animal models of Ureaplasma chorioamnionitis. We will review epidemiological studies of Ureaplasma and BPD in preterm infants and efficacy of antibiotics in preventing preterm labor and BPD.

Ureaplasma species: role in diseases of prematurity

There is accumulating epidemiologic and experimental evidence that intrauterine or postnatal infection with Ureaplasma species is a significant risk factor for adverse pregnancy outcomes and complications of extreme preterm birth such as bronchopulmonary dysplasia and intraventricular hemorrhage. In a cohort of very low birth weight infants, Ureaplasma spp were detected by culture or polymerase chain reaction in respiratory secretions, blood, or cerebrospinal fluid of almost half of the subjects, suggesting that this organism is the most common pathogen affecting this population. This review summarizes the evidence supporting the hypothesis that Ureaplasma-mediated inflammation in different compartments (intrauterine, lung, blood, or brain) during a common developmental window of vulnerability contributes to preterm labor and lung and brain injury. Appropriate methods for detecting these fastidious organisms and potential strategies to prevent or ameliorate the effects of Ureaplasma infection are discussed.

Congenital and opportunistic infections: Ureaplasma species and Mycoplasma hominis

There is strong evidence from clinical and experimental animal studies that ureaplasmas can invade the amnionic sac and induce an inflammatory response resulting in chorioamnionitis, preterm labor and neonatal lung injury. The ability of Ureaplasma spp. and Mycoplasma hominis to cause pneumonia, bacteremia, and meningitis in newborns can no longer be questioned. The association of Ureaplasma spp. with bronchopulmonary dysplasia has been supported by the majority of observational studies, but proof of causality is still lacking. The availability of molecular diagnostic technologies has enabled the designation of the two Ureaplasma biovars as individual species, but additional work must be done to establish whether there is differential pathogenicity between the Ureaplasma spp. or among their respective serovars. Future investigations to prevent prematurity should be directed toward identification and localization of specific micro-organisms combined with targeted antibiotic trials to determine whether such interventions can improve long-term infant outcomes.

Role of Ureaplasma species in neonatal chronic lung disease: epidemiologic and experimental evidence

The contribution of Ureaplasma respiratory tract colonization to the pathogenesis of bronchopulmonary dysplasia in preterm infants has been debated for over 20 y. We review the current understanding of the role of inflammation in altered developmental signaling in the preterm lung and the evidence from human studies and experimental models that Ureaplasma-mediated inflammation produces the BPD phenotype. We propose that Ureaplasma infection initiated in utero and augmented postnatally by exposure to volutrauma and oxygen elicits a sustained, dysregulated inflammatory response in the immature lung that impairs alveolarization, and stimulates myofibroblast proliferation and excessive collagen and elastin deposition. Potential strategies to prevent or ameliorate the effects of Ureaplasma infection in utero and in the preterm lung are discussed.

Amnionitis with Ureaplasma urealyticum or other microbes leads to increased morbidity and prolonged hospitalization in very low birth weight infants

OBJECTIVE

To investigate the influence of culture proven intrauterine infection on preterm morbidity and to test the effect of antimicrobial treatment.

METHODS

Retrospective cohort study conducted between October 1997 and February 2001 in patients with preterm premature rupture of membranes or preterm labor. Vaginal swabs were sampled and amniocentesis for microbiologic culture of the amniotic fluid was performed. Patients with Ureaplasma urealyticum in the amniotic fluid were treated with josamycin. Infants were followed post partum according to birth weight, gestational age, APGAR score and infant morbidity.

RESULTS

In 49 eligible patients, 40% of cultures were positive, 22% for Ureaplasma urealyticum, 12% for other bacteria and 6% for candida. Children of mothers with positive amniotic fluid cultures had significantly lower gestational ages (26+4 weeks for Ureaplasma urealyticum [p=0.04] and 25+5 weeks for other microorganisms [p=0.0017] versus 28+6 weeks for mothers with negative amniotic fluid cultures) and lower birth weights (975 g [n.s.] and 828 g [p=0.0072] versus 1,041 g) but were appropriate for their gestational ages. 33.3% and 66.7% versus 24% of the children were mechanically ventilated [n.s.], duration of mechanical ventilation was 5.3 [p=0.02] and 10.1 days [p=0.04] versus 1.4 days, and prevalence of chronic lung disease was 38% and 33% versus 11% [n.s.]. Prevalence of severe intraventricular hemorrhage (12.5% [n.s.] and 33% [p=0.04] versus 3.4%) and nosocomial infections (50% for both groups of positive cultures versus 10.3% for negative cultures, p=0.02 and 0.03, respectively) was higher and median length of stay was significantly longer (121 [p=0.02] and 107 days [p=0.03] versus 60 days) in these patients. Maternal positive vaginal swab cultures were not associated with any of the above-mentioned factors. In none of the patients treated with macrolids for proven Ureaplasma urealyticum amnionitis could the microbes be eradicated.

CONCLUSION

Maternal positive amniotic fluid cultures have been associated with lower gestational age and lower birth weight. Rate of infant morbidity was higher and length of stay was significantly longer in this group. Positive vaginal swabs were not predictive for infant morbidity. Treatment of mothers showing positive amniotic fluid cultures with macrolids was not effective.

Certain type of chronic lung disease of newborns is associated with Ureaplasma urealyticum infection in utero

BACKGROUND

Recent studies of chronic lung disease (CLD) of newborns emphasize the contribution of antenatal infection. However, the association of Ureaplasma urealyticum infection and CLD has been controversial. The purpose of the present paper was to determine whether U. urealyticum is associated with chorioamnionitis (CAM) and a certain type of CLD.

METHODS

One hundred and five infants <32 weeks of gestation who were admitted to the neonatal intensive care unit at Jichi Medical School Hospital, who underwent both histological and microbiological examinations and who survived to discharge were included. CAM was determined by histological examination. Placenta, gastric and tracheal aspirates, and nasopharyngeal swabs were cultured for Mycoplasma and other microorganisms. CLD was defined as oxygen needed at 28 days of age with symptoms of persistent respiratory distress and hazy or emphysematous and fibrous appearance upon X-ray. CLD was further divided into two subtypes according to the presence of antenatal infection.

RESULTS

CAM was associated with premature rupture of membrane (odds ratio [OR], 10.19; 95% confidence interval [CI]: 3.10-33.56), placental colonization of U. urealyticum (OR 6.73, 95%CI: 1.89-23.91), neonatal colonization of other microorganisms (OR 7.33, 95%CI: 1.22-44.13) and level of IgM (OR 1.06, 95%CI: 1.01-1.11). Comparisons between CLD and non-CLD patients showed that gestational age (OR 0.43, 95%CI: 0.30-0.61) and white blood cell count (WBC) at birth (OR 1.06, 95%CI: 1.01-1.11) were risk factors for CLD, while gestational age (OR 0.38, 95%CI: 0.23-0.64), neonatal colonization of U. urealyticum (OR 5.98, 95%CI: 1.17-30.6) and WBC (OR 1.08, 95%CI: 1.01-1.15) were independent risk factors for infection-related CLD compared with non-CLD. Within CLD, infection-related CLD was associated with neonatal colonization of U. urealyticum (OR 43.7, 95%CI: 2.84-673.8) and WBC (OR 1.27, 95%CI: 1.07-1.50).

CONCLUSIONS

Placental colonization of U. urealyticum was significantly related to CAM; and neonatal colonization of U. urealyticum and leukocytosis at birth were risk factors for infection-related CLD.

Detection of ureaplasma DNA in endotracheal samples is associated with bronchopulmonary dysplasia after adjustment for multiple risk factors

Microorganisms are hypothesized to contribute to the pathogenesis of bronchopulmonary dysplasia (BPD) in very low birth weight (VLBW) infants. This hypothesis remains controversial. We sought to determine whether endotracheal colonization with Ureaplasma sp., adenovirus, or Chlamydia sp. increases the risk of BPD. Intubated VLBW infants were included. Polymerase chain reaction (PCR) analysis was used to detect Ureaplasma sp., adenovirus, and Chlamydia sp. The outcome measure was BPD or death due to lung disease. Detection of microorganisms was compared between subjects with and without BPD. Logistic regression was used to control for covariates. Of 139 subjects, 33 (25%) screened positive for Ureaplasma sp., 22 of 136 (16%) were positive for adenovirus; eight of 133 (6%) were positive for Chlamydia sp. At 36 wk postmenstrual age, 14 patients had died, 68 (57%) had BPD. Detection of Ureaplasma sp. was associated with BPD or death (p < 0.001); adenovirus (p = 0.52) and Chlamydia sp. (p = 0.33) were not. Controlling confounding factors, the odds ratio for Ureaplasma sp. and BPD or death was 4.2 (95% CI 1.03, 17). In our population, detection of Ureaplasma sp., but not adenovirus or Chlamydia sp. was associated with BPD or death due to lung disease.

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.

The significance of Ureaplasma urealyticum as a pathogenic agent in the paediatric population

PURPOSE OF REVIEW

Ureaplasma urealyticum is a frequent commensal in the lower genital tract of sexually active women. It may be transmitted perinatally from the colonized mother to her offspring, often resulting in prematurity and neonatal disease. The microorganism also sustains a causative role for infectious diseases in older children.

RECENT FINDINGS

U. urealyticum infection can be diagnosed by culture, polymerase chain reaction, and the detection of specific antibodies. Neonatal infection has been implicated in various pathological conditions including pneumonia, chronic lung disease, central nervous system disorders, sepsis, osteomyelitis and even death. Older children may present with wheezing, pneumonitis, pertussis-like syndrome and different forms of arthritis. Large well-designed trials have demonstrated that the regular administration of antibiotics to vaginally colonized women are not beneficial in terms of preventing preterm labour. Macrolide-containing antibiotic regimens are, however, recommended for preterm premature rupture of the membranes. Erythromycin treatment of ureaplasma respiratory colonized premature infants shows no reduction in the incidence of chronic lung disease. Treatment of central nervous system infections, sepsis and arthritides includes tetracyclines, fluoroquinolones and anti-inflammatory agents, respectively.

SUMMARY

This review covers recent evidence concerning the role of U. urealyticum as a pathogen during childhood. It also includes an evaluation of contemporary diagnostic techniques and optimal therapeutic approaches.

Nosocomial infections in a Dutch neonatal intensive care unit: surveillance study with definitions for infection specifically adapted for neonates

The incidence of nosocomial infection in neonatal intensive care units (NICUs) is high compared with other wards. However, no definitions for hospital-acquired infection are available for NICUs. The aim of this study was to measure the incidence of such infections and to identify risk factors in the NICU of the VU University Medical Center, which serves as a level III regional NICU. For this purpose, a prospective surveillance was performed in 1998-2000. We designed definitions by adjusting the current definitions of the Centers for Disease Control and Prevention (CDC) for children <1 year of age. Birth weight was stratified into four categories and other baseline risk factors were dichotomized. Analysis of risk factors was performed by Cox regression with time-dependent variables. The relationship between the Clinical Risk Index for Babies (CRIB) and nosocomial infection was investigated. Furthermore, for a random sample of cases, we determined whether bloodstream infection and pneumonia would also have been identified with the CDC definitions. Seven hundred and forty-two neonates were included in the study. One hundred and ninety-one neonates developed 264 infections. Bloodstream infection (N=138, 14.9/1000 patient-days) and pneumonia (N=69, 7.5/1000 patient-days) were the most common infections. Of bloodstream infections, 59% were caused by coagulase-negative staphylococci; in 21% of neonates, blood cultures remained negative. In 25% of pneumonias, Enterobacteriaceae were the causative micro-organisms; 26% of cultures remained negative. Compared with the Nosocomial Infections Surveillance System (NNIS) of the CDC, our device utilization ratios and device-associated nosocomial infection rates were high. The main risk factors for bloodstream infection were birth weight [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.45-2.17] and parenteral feeding with hospital-pharmacy-produced, all-in-one mixture 'Minimix' (HR 3.69, 95%CI 2.03-6.69); administration of intravenous antibiotics (HR 0.39, 95%CI 0.26-0.56) was a protective risk factor. The main risk factors for pneumonia were low birth weight (HR 1.37, 95%CI 1.01-1.85) and mechanical ventilation (HR 9.69, 95%CI 4.60-20.4); intravenous antibiotics were protective (HR 0.37, 95%CI 0.21-0.64). In a subcohort of 232 very-low-birthweight neonates, the CRIB was not predictive for infection. With the CDC criteria, only 75% (21/28) of bloodstream infections and 87.5% of pneumonias (21/24) would have been identified. In conclusion, our local nosocomial infection rates are high compared with those of NICUs participating in the NNIS. This can be partially explained by: (1) the use of our definitions for nosocomial infection, which are more suitable for this patient category; and (2) the high device utilization ratios.

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.

Increased intrauterine frequency of Ureaplasma urealyticum in women with preterm labor and preterm premature rupture of the membranes and subsequent cesarean delivery

OBJECTIVE

The purpose of this study was to evaluate the prevalence of microbial invasion of the amniotic cavity at the time of preterm cesarean delivery for therapy-resistant preterm labor or preterm premature rupture of membranes, which are events that commonly are induced by infection, and to compare this group of patients with a group of patients who underwent preterm cesarean delivery for indications other than preterm labor or preterm premature rupture of membranes.

STUDY DESIGN

We studied 207 consecutive women between 23 and 34 weeks of gestation who underwent cesarean delivery. These patients were divided into 3 groups according to the indication for cesarean delivery: patients with preterm labor (group 1), patients with preterm premature rupture of membranes (group 2), and patients with other indications (group 3). In the course of the surgical procedure, amniotic fluid, amniotic membrane, and placental tissue specimens were collected for the detection of pathogens.

RESULTS

Ureaplasma urealyticum was detected in 43.9% (58/132) of the patients of groups 1 and 2, with no significant difference between these 2 subgroups. In group 3, which served as the comparison group, Ureaplasma urealyticum was isolated in only 2.7% (2/75) of the patients. Ureaplasma urealyticum as a single pathogen was more frequent than all obligate pathogens together (43.9% vs 39.3%).

CONCLUSION

Our results provide evidence for an association between intrauterine colonization with Ureaplasma urealyticum and both therapy-resistant preterm labor and preterm premature rupture of membranes.

Mycoplasmas and ureaplasmas as neonatal pathogens

The genital mycoplasmas represent a complex and unique group of microorganisms that have been associated with a wide array of infectious diseases in adults and infants. The lack of conclusive knowledge regarding the pathogenic potential of Mycoplasma and Ureaplasma spp. in many conditions is due to a general unfamiliarity of physicians and microbiology laboratories with their fastidious growth requirements, leading to difficulty in their detection; their high prevalence in healthy persons; the poor design of research studies attempting to base association with disease on the mere presence of the organisms in the lower urogenital tract; the failure to consider multifactorial aspects of diseases; and considering these genital mycoplasmas only as a last resort. The situation is now changing because of a greater appreciation of the genital mycoplasmas as perinatal pathogens and improvements in laboratory detection, particularly with regard to the development of powerful molecular nucleic acid amplification tests. This review summarizes the epidemiology of genital mycoplasmas as causes of neonatal infections and premature birth; evidence linking ureaplasmas with bronchopulmonary dysplasia; recent changes in the taxonomy of the genus Ureaplasma; the neonatal host response to mycoplasma and ureaplasma infections; advances in laboratory detection, including molecular methods; and therapeutic considerations for treatment of systemic diseases.

Ureaplasma urealyticum, Mycoplasma hominis et pathologiesnéonatales : Données personnelles et revue de la littérature

Ureaplasma urealyticum and Mycoplasma hominis colonized 20-40% of newborns and are more frequent in premature. They are responsible for localized infections such as pleural effusion, pneumopathy, adenopathy, abscess or systemic sepsis. An important hyperleukocytosis is often associated with pulmonary infections. Their responsibility, as pathogen agents, is questionable in some non bacterial meningitis. There is large controversy for their role as cofactor, in chronic lung disease (bronchopulmonary dysplasia) and periventricular leukomalacia, because of a too low number of newborns in prospective trials. Genital mycoplamas are resistant to beta lactamines. Macrolides have a good sensitivity, particularly josamycine, but Mycoplasma hominis is resistant to erythromycin. For systemic sepsis, fluoroquinolones such as ciprofloxacine have less deleterious effects than IV erythromycin.

Modeling and Remodeling of the Lung in Neonatal Chronic Lung Disease

Neonatal chronic lung disease (CLD) is the major long-term pulmonary complication of preterm birth affecting about 20% of infants who need mechanical ventilation. CLD is the result of abnormal repair processes following inflammatory lung injury that lead to remodeling of the lung. Inflammation may be initiated by a variety of stimuli including mechanical ventilation, oxygen toxicity and infection. The resultant neutrophil chemotaxis and degranulation leads to the release of enzymes such as matrix metalloproteinases that can cause proteolysis of the lung extracellular matrix. Abnormal healing with remodeling leads to poorly compliant lungs with reduced capacity for gas exchange. Drugs can influence the normal process of lung modeling or remodeling. Fetal lung development can be influenced by glucocorticosteroids and inflammation. Both can cause abnormal lung modeling with fewer, larger alveoli and accelerated lung maturation, which confers benefits in terms of reduced morbidity and mortality from respiratory distress syndrome but potentially increases the risk of subsequent lung injury. Antioxidants, such as retinol (vitamin A), administered post-natally may reduce the effects of oxidative stress leading to a modest reduction in CLD but they require repeated intramuscular injections. Postnatal glucocorticosteroid therapy can modify the lung inflammatory response and reduce CLD but it can also have detrimental effects on the developing brain and lung, thereby creating a clinical dilemma for neonatologists. Proteinase inhibitors may be a rational therapy but more research is needed before they can be accepted as a treatment for preterm neonates.'Modeling' is defined as planning or forming that follows a set pattern. The term is used to describe the normal process of lung growth and development that culminates in mature branching alveolar air spaces surrounded by a network of capillaries. Normal lung modeling occurs under a variety of genetic and hormonal influences that can be altered, leading to abnormal patterns of growth. 'Remodeling' is defined as altering the structure of or re-making and, in the case of the lung, is used to describe the abnormal patterns of lung growth that occur after lung injury. Modeling and remodeling of the lungs occur to an extent throughout life but never more rapidly than during the fetal and early neonatal periods, and factors that influence this process may lead to development of neonatal CLD. Some of the factors involved in normal and abnormal lung modeling and inflammation and glucocorticosteroid-induced remodeling in the perinatal period, in the context of neonatal CLD, are reviewed with considerations of how various drugs may influence these processes.

Maternal genital colonization with Ureaplasma urealyticum promotes preterm delivery: association of the respiratory colonization of premature infants with chronic lung disease and increased mortality

BACKGROUND

Infection of the chorioamnion with Ureaplasma urealyticum has been associated with low birth weight. Respiratory tract colonization in preterm infants has been associated with the development of chronic lung disease (CLD). The purpose of the present study was to determine the frequency of colonization of the mother's vagina and the preterm infant's respiratory tract and to associate U. urealyticum with premature birth and with development of CLD in the newborn.

METHODS

The present prospective study involved 126 mothers with preterm delivery and 125 mothers with full-term delivery, as well as their offspring. Vaginal secretion specimens were obtained from each mother before delivery. Rhinopharyngeal secretion or tracheal lavage specimens were collected after the birth of each premature and full-term infant and then periodically during hospitalization.

RESULTS

Vaginal Ureaplasma colonization occurred among 36.5% of mothers with preterm delivery and among 38% of mothers with full-term delivery. The rate of vertical transmission was 33% and 17% for mothers with preterm delivery and mothers with full-term delivery, respectively. The transmission rate for infants, according to birth weight, was as follows: 60%, for infants with a birth weight of <1000 g; 50%, for infants with a birth weight of 1000-1500 g; and 15.3%, for infants with a birth weight of > or =1500 g (P=.001). The median gestational age of preterm infants born to colonized mothers was 28.5 weeks, and that of preterm infants born to noncolonized mothers was 32 weeks (P<.0001). The median birth weight of colonized preterm infants was 1135 g, and that of noncolonized infants was 1670 g (P<.0001). Twenty-four percent of preterm infants and 10% of full-term infants were colonized with U. urealyticum. Of colonized preterm infants, 27% developed CLD, compared with 9% of noncolonized infants (P=.03). Mortality was significantly higher among colonized preterm infants (P=.003).

CONCLUSIONS

The rate of vertical transmission is highest among preterm infants with a birth weight of <1500 g. Vaginal colonization with Ureaplasma organisms is associated with premature delivery. Colonization of the respiratory tract of infants is associated with the development of CLD and with increased mortality.

Effects of antenatal colonization with ureaplasma urealyticum on pulmonary disease in the immature baboon

Current nonhuman models for bronchopulmonary dysplasia have not included perinatal infection. We studied the effects of antenatal Ureaplasma urealyticum (Uu) infection in the 125-d immature baboon. Ten 125-d gestation (term = 185 d) baboon dams were delivered after intra-amniotic inoculation with Uu. Serial blood and tracheal aspirate samples were analyzed for Uu colony-forming units, IL-6, IL-8, and cell counts. Physiologic parameters were serially recorded. Lung histology was examined after 14 d of ventilation and compared with unexposed controls. All Uu-exposed animals had >4 x 102 CFU in tracheal aspirate at 24 h. Four of nine Uu animals remained heavily colonized [(+) Uu] at necropsy (>6 x 103). Five animals had negative or low tracheal colony-forming units. All Uu animals had significant increases for white blood cells, IL-6, and IL-8 in amniotic and fetal lung fluid. Compared with controls, (+) Uu animals had significantly higher fraction of inspired oxygen, airway pressures, oxygenation index, and ventilation efficiency index between 48 and 240 h and had significantly elevated tracheal IL-6 and IL-8 concentrations between 72 and 240 h. Compared with controls (-) Uu animals had significantly better oxygenation index and ventilation efficiency index scores between 48 and 144 h. Lung histopathology in both Uu groups showed more severe bronchiolitis and interstitial pneumonitis compared with controls. Two patterns of disease were observed after Uu perinatal infection. Persistent colonization manifested a picture consistent with acute pneumonitis, worse lung function from 2 to 10 d, and prolonged elevated tracheal cytokines. Colonized animals that subsequently cleared Uu from the lung demonstrated early improved lung function compared with unexposed controls yet still manifested mixed bronchiolitis and interstitial pneumonitis at necropsy. Inherent immune system responses may determine outcome of perinatal Ureaplasma colonization.

Ureaplasma in lung. 2. Association with bronchopulmonary dysplasia in premature newborns

Infants with Ureaplasma urealyticum in the lower respiratory tract are at risk for chronic lung disease (CLD) or bronchopulmonary dysplasia (BPD) but causality has been difficult to prove. The goal of this study was to identify ureaplasma in human neonatal lung tissue using the in situ hybridization (ISH) procedure described in Part 1 (Exp. Mol. Pathol., in press) of this report. By correlating their presence with the histopathologic findings, it may be possible to provide further evidence of the pathogenicity of ureaplasmas and their association with BPD. Lung autopsy tissue from seven infants with positive cultures and seven infants with negative cultures for ureaplasma were included in the study. All culture-positive infants were positive for ureaplasma on ISH and all had histopathologic evidence of BPD. Two of the seven infants with negative cultures were positive for ureaplasma with ISH. Of interest, these two infants were also found to have BPD at autopsy. The other five infants with negative cultures were also negative for ureaplasma on ISH and had no evidence of BPD. This study correlates the presence of U. urealyticum by ISH with the finding of BPD on histopathologic evaluation and provides evidence that it has a role in the development of CLD.

Microbial invasion of the amniotic cavity at birth is associated with adverse short-term outcome of preterm infants

AIMS

To determine the frequency and clinical significance of microbial invasion of the amniotic cavity at the time of delivery in preterm infants.

METHODS

Prospective cohort study during June 2001 and January 2002. Preterm infants < 33 + 6 weeks of gestation who had amniotic fluid and placental tissue sampled for culture during cesarean section were included.

RESULTS

Of a total of 80 neonates, 42 had negative culture results, 22 had growth of Ureaplasma urealyticum, and 16 had growth of other pathogens. Isolation of Ureaplasma urealyticum was associated with a decreased risk of developing hyaline membrane disease after birth but a more than 20 times increased risk of developing chronic lung disease. Patients with growth of other pathogens had a significantly higher mortality than patients with negative culture results.

CONCLUSIONS

Isolation of miroorganisms from the amniotic cavity at birth is associated with an adverse outcome of the preterm infant. In the light of extremely small numbers of positive blood cultures in preterm infants after birth, we consider it reasonable to recommend routine culturing of amniotic cavity tissues/fluid obtained during cesarean section in order to increase the identification rate of pathogens potentially involved in the pathogenesis of perinatal infections.

Placental passage of clarithromycin surpasses other macrolide antibiotics

OBJECTIVE

Infection of the amnion cavity with Ureaplasma urealyticum continues to be a therapeutic challenge. The transplacental transfer rates of macrolide antibiotics are low, and tetracyclines and quinolones are contraindicated in pregnancy. The aim of this study was to investigate placental transfer of clarithromycin in a well-studied placental perfusion model to determine whether clarithromycin surpasses the transfer rate of other macrolide antibiotics in similar models.

STUDY DESIGN

Ten placentas that were obtained immediately after delivery were perfused with clarithromycin (3 microg/mL) plus a reference substance (antipyrine). Open circulation placental preparations were used to evaluate steady-state pharmacodynamics and transplacental gradient formation. Drug concentrations were measured by high-performance liquid chromatography.

RESULTS

The mean transplacental transfer of clarithromycin was 6.1% (95% CI, 1.8%).

CONCLUSION

Because of its enhanced placental passage compared with other macrolide antibiotics, clarithromycin that is given after the first trimester (after embryogenesis) may be an appropriate candidate in treatment trials of genital mycoplasma and ureaplasma infections during pregnancy.

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.

Patterns of colonization with Ureaplasma urealyticum during neonatal intensive care unit hospitalizations of very low birth weight infants and the development of chronic lung disease

BACKGROUND

Ureaplasma urealyticum and its association with chronic lung disease (CLD) of prematurity has remained a controversial topic. To readdress this question, we performed a longitudinal study using culture and polymerase chain reaction to detect U urealyticum in the respiratory tract of very low birthweight infants throughout their neonatal intensive care unit hospitalizations.

METHODS

We screened 125 infants weighing <1500 g and/or <32 weeks' gestational age over a 12-month period, collecting endotracheal, nasopharyngeal, and throat specimens on days of age 1, 3, 7, and weekly thereafter. CLD was defined as dependency on supplemental oxygen at 28 days and at 36 weeks' postconceptional age.

RESULTS

Forty infants (32%) had 1 or more positive specimens by culture or polymerase chain reaction. We identified 3 patterns of U urealyticum colonization: persistently positive (n = 18), early transient (n = 14), and late acquisition (n = 8). We compared the rates of CLD in each of the 3 colonized groups with the rate of CLD in the noncolonized group. We found a significantly higher rate of CLD at 28 days of age (odds ratio: 8.7; 95% confidence interval: 3.3, 23) and at 36 weeks' postconception (odds ratio: 38.5, 95% confidence interval: 4.0, 374) only for infants with persistently positive colonization.

CONCLUSIONS

This study demonstrates that the risk of developing CLD varies with the pattern of U urealyticum colonization. Only the persistently positive colonization pattern, which accounted for 45% of the U urealyticum-positive infants, was associated with a significantly increased risk of development of CLD.

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

Ureaplasma urealyticum is frequently isolated from tracheal aspirates of very low birthweight infants who go on to develop chronic lung disease. The use of erythromycin has been advocated in ventilated very low birthweight infants who are colonised with U. urealyticum, although the association between U. urealyticum and chronic lung disease remains controversial. There are only two randomised, controlled trials involving a total of 37 U. urealyticum-positive very low birthweight infants. Both trials failed to demonstrate a reduction in the incidence of chronic lung disease after 7 or 10 days of erythromycin. On the other hand, there are reports of rare but serious adverse effects of erythromycin in newborn infants including sudden cardiovascular compromise and hypertrophic pyloric stenosis. We conclude that, at present, there is insufficient evidence to support the use of erythromycin for the treatment of incipient chronic lung disease in very low birthweight infants colonised with U. urealyticum.

Identification and quantification of ureaplasmas colonizing the respiratory tract and assessment of their role in the development of chronic lung disease in preterm infants

BACKGROUND

The role of Ureaplasma urealyticum in the development of chronic lung disease (CLD) in preterm infants continues to be disputed. Recently U. urealyticum has been found to consist of two species, U. urealyticum and Ureaplasma parvum, a finding that has not been considered in previous studies of CLD. This study examined the possible relationships between development of CLD and respiratory colonization by these newly redefined species, their concentrations in lower respiratory secretions and the effect of pulmonary surfactant treatment on these relationships in preterm infants with birth weights < 1500 g.

METHODS

Endotracheal aspirates (ETA) were collected from intubated infants when airway suctioning was medically required. ETA were stored at -80 degrees C until quantitative cultures for ureaplasmas and Mycoplasma hominis were performed. Culture results were correlated with development of CLD.

RESULTS

Of 475 infants (birth weights < 1500 g) admitted during the 2-year study period, 272 were excluded because they were not intubated or were extubated before ETA could be obtained. An additional 28 infants died, were discharged or were transferred before they could be assessed for CLD. From the remaining 175 infants ureaplasmas were isolated from 66 (38%). No statistically significant associations were identified between development of CLD and the Ureaplasma species isolated, or concentration of ureaplasmas in lower respiratory secretions. These findings were not altered by treatment with pulmonary surfactant (Survanta).

CONCLUSION

Lower respiratory colonization by ureaplasmas does not appear to be a contributory cause of CLD in preterm infants.

Inhibition of macrophage proinflammatory cytokine expression by steroids and recombinant IL-10

Chronic lung disease (CLD) of prematurity is a prolonged respiratory failure in very-low-birth-weight neonates. Proinflammatory cytokines have been implicated in the development of CLD. Steroids have been shown to produce some improvement in neonates with this disease. The purpose of this study was to evaluate the downregulation of these proinflammatory cytokines by dexamethasone, budesonide and recombinant IL-10 (rIL-10) in order to elucidate the mechanism of the clinical benefit of steroids in babies. Our results showed that dexamethasone, budesonide and rIL-10 significantly inhibited both IL-6 and TNF-alpha production in the THP-1 cell line stimulated by lipopolysaccharide and Ureaplasma urealyticum antigen. Similar effects were found in macrophages from tracheobronchial aspirate fluid from newborn infants. In the rat alveolar macrophage cell line, steroids inhibited IL-6 and TNF-alpha production, while rat rIL-10 did not significantly decrease production. In conclusion, steroids and human rIL-10 were able to downregulate proinflammatory cytokine production, which may explain the beneficial effect of steroids and suggests that rIL-10 could be tried as an anti-inflammatory agent in neonates with a high risk of CLD.

[Colonization by Ureaplasma urealyticum and chronic lung disease in premature newborn infants under 32 weeks of gestation]

Colonization of the respiratory tract of premature newborn infants by genital mycoplasma is suspected to be associated with chronic lung disease.

METHODS AND PATIENTS

We prospectively determined the prevalence of genital mycoplasma colonization with nasopharyngeal or endotracheal culture in preterm neonates younger than 32 weeks gestation and its possible association with the development of chronic lung disease in a prospective study.

RESULTS

Fifty-nine infants were enrolled and 11 (19%) were colonized with Ureaplasma urealyticum. In the subgroup of 45 ventilated infants, seven of seven U. urealyticum-positive infants developed chronic pulmonary disease versus ten of 38 (26%) of U. urealyticum-negative infants (relative risk [RR] = 3.8; 95% confidence interval [CI] 2.2 to 6.5, P < 0.001). U. urealyticum-colonized infants had a lower median birth weight (760 vs 1,083 g, P = 0.04), a lower gestational age (26 vs 28 weeks, P = 0.03), and a higher incidence of symptomatic patent ductus arteriosus (P = 0.03). These potential confounding factors may partially explain the association between U. urealyticum and chronic pulmonary disease. However, this association remained statistically significant when the analysis was restricted to infants with birth weight of 1,000 g or less (RR = 2.3; 95% CI 1.3 to 4, P = 0.02) or to infants with a patent ductus arteriosus (RR = 2; 95% CI 1.3 to 3.1, P = 0.02).

CONCLUSION

Colonization with U. urealyticum in ventilated preterm neonates younger than 32 weeks gestation is a significant risk factor of developing chronic pulmonary disease.

Perinatal Ureaplasma urealyticum infection increases the need for hospital treatment during the first year of life in preterm infants

To explore the association of perinatal Ureaplasma urealyticum infection and the need for hospital care during infancy, a cohort of preterm infants were prospectively followed for 12 months. Perinatal U. urealyticum infection was defined as the presence of U. urealyticum in the samples obtained from the trachea and blood. During the first year of life, the infants of the study cohort required 73 hospital admissions resulting in 734 hospital days. The 22 infants with perinatal U. urealyticum infection needed more hospital days for therapy than the 18 infants without infection (546 vs. 188 days, P = 0.042). The difference was caused by an increase in respiratory tract diseases among children with perinatal U. urealyticum infection. Chronic lung disease caused more admissions in infants with perinatal U. Urealyticum infection than without it (P = 0.035). The results indicate that perinatal U. urealyticum infection affects the health of premature infants far beyond the perinatal period.

A risk-benefit assessment of drugs used for neonatal chronic lung disease

Improvements in neonatal intensive care have resulted in more extremely low birthweight babies surviving who are at risk of developing chronic lung disease. The preterm lung is vulnerable as it is both structurally immature and deficient in surfactant and antioxidant defences. Mechanical ventilation and high inspired oxygen concentrations are often necessary for preterm babies to survive but they can cause pulmonary inflammation which leads to lung damage. Abnormal healing in the presence of ongoing inflammation leads to airways remodelling which can result in protracted respiratory problems in these babies. A commonly used definition for chronic lung disease is the requirement for supplemental oxygen beyond 36 weeks' postconception. Many drugs that are commonly used for chronic lung disease have not been subjected to proper randomised controlled trials but are widely used on the basis of small studies showing short term benefits. They can be broadly divided into 2 groups. First, there are preventative drugs that are administered early to reduce oxygen toxicity and pulmonary inflammation. Secondly, there are those administered in established chronic lung disease, designed to reduce respiratory morbidity. Pulmonary inflammation in the neonate is reduced by systemic corticosteroids. Corticosteroid therapy within the first 2 weeks of life enables earlier extubation of preterm babies with subsequent reduced chronic lung disease and improved neonatal survival when given between 7 and 14 days. However, there is an increased risk of gastrointestinal haemorrhage, metabolic derangement, ventricular hypertrophy and potential effects on long term growth and brain development. Diuretics and inhaled bronchodilators improve pulmonary compliance and reduce oxygen requirements in established chronic lung disease but probably have little effect in reducing the incidence. In babies with established chronic lung disease, home oxygen therapy enables earlier discharge and prophylaxis against respiratory syncytial virus can reduce morbidity from bronchiolitis. All of the above therapies have adverse effects that need to be considered before initiating treatment. Recently, new drugs have become available which may be beneficial. These include inhaled nitric oxide for reduction of ventilation-perfusion mismatching, recombinant human superoxide dismutase for protection against oxidative stress and alpha-1 proteinase inhibitor which may reduce airways remodelling. At present these therapies are undergoing clinical trials. Exogenous surfactant is beneficial in respiratory distress syndrome and may reduce the risk of chronic lung disease but there have been no randomised controlled trials of its use in established chronic lung disease. Drugs which have been tried unsuccessfully include erythromycin, ambroxol and mast cell stabilisers.

Role of ureaplasma urealyticum in lung disease of prematurity

AIM

To examine the role of Ureaplasma urealyticum colonisation or infection in neonatal lung disease.

METHODS

Endotracheal aspirates from ventilated infants less than 28 weeks of gestation were cultured for U urealyticum and outcomes compared in infants with positive and negative cultures.

RESULTS

U urealyticum was isolated from aspirates of 39 of 143 (27%) infants. Respiratory distress syndrome (RDS) occurred significantly less often in colonised, than in non-colonised infants (p=0.002). Multivariate logistic regression analysis showed that in singleton infants, ureaplasma colonisation was the only independent (negative) predictor of RDS (OR 0.36; p=0. 02). Both gestational age (OR 0.46; p=0.006) and isolation of U urealyticum (OR 3.0; p=0.05) were independent predictors of chronic lung disease (CLD), as defined by requirement for supplemental oxygen at 36 weeks of gestational age. Multiple gestation was also a major independent predictor of RDS and CLD.

CONCLUSIONS

Colonisation or infection with ureaplasma apparently protects premature infants against the development of RDS (suggesting intrauterine infection). However, in singleton infants, it predisposes to development of CLD, independently of gestational age. Treatment of affected infants after birth is unlikely to significantly improve the outcome and methods are required to identify and treat the women with intrauterine ureaplasmal infection, before preterm delivery occurs.

Ureaplasma urealyticum and chronic lung disease in very low birth weight infants during the exogenous surfactant era

BACKGROUND

An association between recovery of Ureaplasma urealyticum from the respiratory tract of very low birth weight (VLBW) infants (< or =1500 g) and later chronic lung disease (CLD) was reported by several authors before the routine use of exogenous surfactant (SURF). We sought to assess whether this relation persists in the era of routine SURF.

METHODS

We prospectively studied a cohort of 105 VLBW infants who required mechanical ventilation at < 12 h of age. Tracheal aspirates for U. urealyticum culture were obtained before administration of SURF or antibiotics. Clinicians were unaware of U. urealyticum status. Chest radiographs at 28 days were reviewed by a single pediatric radiologist, blinded to U. urealyticum status. Sample size was predetermined to detect a 30% increase in CLD among those with U. urealyticum recovery from tracheal culture (U. urealyticum-positive) with alpha <0.05 and beta <0.20.

RESULTS

Of the study infants 22 were U. urealyticum-positive and 83 were U. urealyticum-negative. No differences were found between the groups for birth weight, gestational age, gender, inborn, antenatal or postnatal steroid use, SURF therapy, non-U. urealyticum infection, necrotizing enterocolitis, patent ductus arteriosus, intraventricular hemorrhage or cystic periventricular leukomalacia. At 28 days U. urealyticum-positive patients were significantly more likely to have CLD than U. urealyticum-negative [15 of 22 (68%) vs. 30 of 83 (36%); P < 0.02]. The U. urealyticum-positive patients also required significantly longer courses of supplemental oxygen and mechanical ventilation. No significant differences were found for CLD at 36 weeks postconception or duration of hospitalization, although type II error could not be excluded for these secondary endpoints.

CONCLUSIONS

Respiratory U. urealyticum at or shortly after birth remains associated with CLD at 28 days despite routine use of SURF. Controlled trials of anti-Ureaplasma therapy in U. urealyticum-positive VLBWs as soon after birth as possible may determine whether CLD, duration of respiratory support and attendant costs can be decreased.

Ureaplasma urealyticum respiratory tract colonization is associated with an increase in interleukin 1-beta and tumor necrosis factor alpha relative to interleukin 6 in tracheal aspirates of preterm infants

OBJECTIVE

To determine whether Ureaplasma urealyticum respiratory tract colonization in very low birth weight infants during the first week of life is associated with changes in tracheal aspirate concentrations of the cytokines interleukin 1-beta (IL-1-beta), tumor necrosis factor alpha (TNF-alpha) and IL-6.

METHODS

Infants with birth weights < or =1250 g were prospectively enrolled. Samples were obtained from the endotracheal tube or nasopharynx on Day 1 and again between Days 7 and 10 for U. urealyticum culture. The concentrations of IL-1-beta, TNF-alpha and IL-6 were measured in tracheal aspirate samples by enzyme-linked immunosorbent assay.

RESULTS

There were 18 positive cultures for U. urealyticum from 15 of 96 infants (15.6%). IL-1-beta in tracheal aspirates expressed as concentration per volume or as a ratio of IL-1-beta to IL-6 were 7- and 14.9-fold higher, respectively, in Ureaplasma-positive infants than in Ureaplasma-negative infants (P < 0.05). The TNF-alpha/IL-6 ratio was 18.9 and 15.5 times higher in the Ureaplasma-positive aspirates than in the Ure aplasma-negative aspirates on Day 1 and Days 7 to 10 (P < 0.05). Concentrations of IL-1-beta and TNF-alpha were significantly correlated on Day 1 and Days 7 to 10. Although there was no clinical association demonstrated between U. urealyticum colonization and the development of bronchopulmonary dysplasia (BPD) in this study, infants who developed BPD had significantly higher IL-1-beta concentrations and ratios of IL-1-beta to IL-6 in Day 1 aspirates than infants who did not develop BPD. Conclusions. Isolation of U. urealyticum from the respiratory tract is associated with increased IL-1-beta concentrations and IL-1-beta-IL-6 ratios on Day 1 and increased TNF-alpha-IL-6 ratios on Days 1 and 7 to 10 in tracheal aspirates of colonized infants. Infants who developed BPD had higher IL-1-beta concentrations and IL-1-beta-IL-6 ratios, suggesting that these may be early markers of lung inflammation.