D. T. Crouse

Ureaplasma urealyticum intrauterine infection: role in prematurity and disease in newborns.

Ureaplasma urealyticum, a common commensal of the urogenital tract of sexually mature humans, is gaining recognition as an important opportunistic pathogen during pregnancy. While its etiologic significance in many aspects of adverse pregnancy remains controversial, recent evidence indicates that U. urealyticum in the absence of other organisms is a cause of chorioamnionitis. Furthermore, ureaplasmal infection of the chorioamnion is significantly associated with premature spontaneous labor and delivery. In at least some cases, it appears to be causal. Present evidence indicates that U. urealyticum is a cause of septicemia, meningitis, and pneumonia in newborn infants, particularly those born prematurely. There is strong but not definitive evidence that ureaplasmal infection of the lower respiratory tract can lead to development of chronic lung disease in very low-birth-weight infants. Although risk factors for colonization of the lower genitourinary tract have been identified, little information is available concerning risk factors for intrauterine infection and host immune responses to invasive infection. Recent establishment of animal models of respiratory and central nervous system diseases should provide an opportunity to evaluate risk factors, pathogenic mechanisms, and operative immune mechanisms. However, the most critical need is additional information concerning indications for diagnosis and treatment as well as efficacy of treatment. Images

ASSOCIATION OF UREAPLASMA UREALYTICUM INFECTION OF THE LOWER RESPIRATORY TRACT WITH CHRONIC LUNG DISEASE AND DEATH IN VERY-LOW-BIRTH-WEIGHT INFANTS

Endotracheal aspirates from 200 infants who weighted less than or equal to 2500 g and who had evidence of respiratory disease were cultured within 24 h of birth for mycoplasmas, chlamydiae, viruses, and bacteria to evaluate the relation between lower respiratory tract infection and development of chronic lung disease and/or death. Ureaplasma urealyticum, an organism not visible on gram stain, not recovered on routine bacteriological media, and not susceptible to antibiotics commonly used to treat neonatal infections, was the single most common organism isolated. 14% of isolates were from infants born by caesarean section with intact membranes, which indicated that infection had occurred in utero. The findings probably represented true infection of the lower respiratory tract because the organism was recovered in pure culture in numbers greater than 10(3) from 85% of the infants, and also from the blood in 26% of infants. Those infants less than or equal to 1000 g with Ureaplasma urealyticum infection of the lower respiratory tract were twice more likely to have chronic lung disease or to die than were infants of similar birth-weight but who were uninfected, or infants greater than 1000 g. Very-low-birth-weight infants infected with ureaplasmas did not differ from those uninfected, either in demographic features or in potential risk factors for chronic lung disease.

CHRONIC UREAPLASMA UREALYTICUM AND MYCOPLASMA HOMINIS INFECTIONS OF CENTRAL NERVOUS SYSTEM IN PRETERM INFANTS

In a prospective study of meningitis in 100 predominantly preterm infants, Ureaplasma urealyticum was isolated from the cerebrospinal fluid (CSF) of 8 and Mycoplasma hominis from the CSF of 5 babies undergoing investigation of suspected sepsis or treatment of hydrocephalus. U urealyticum was isolated from 6 infants with severe intraventricular haemorrhage and from 3 with hydrocephalus. In 4 babies multiple isolations were made over several weeks. There were clinical features of congenital infection with major neurological impairment in 1 infant infected with M hominis. Diagnosis is difficult because these organisms cannot be seen on gram stain and cannot readily be cultivated on routine bacteriological media, and CSF pleocytosis may be absent. This study, which used appropriate mycoplasmal media, shows that U urealyticum and M hominis are the most common microorganisms isolated from the CSF of newborn infants in a high-risk population.

Antibiotic susceptibilities and therapeutic options for Ureaplasma urealyticum infections in neonates.

The appreciation of Ureaplasma urealyticum as a human pathogen and documentation of antibiotic resistance have heightened interest in drug susceptibilities and treatment alternatives for patients infected with this organism. Neonates pose special problems when therapy must be considered because of potential toxicities, clinical unfamiliarity or lack of experience. Forty-three isolates of U. urealyticum obtained from the lower respiratory tracts of neonates were tested against chloramphenicol, ciprofloxacin, clindamycin, erythromycin, doxycycline, and gentamicin by a microbroth dilution technique in 10B broth. In vitro resistance was observed in 1 or more strains for each of the drugs tested, except for erythromycin (minimal inhibitory concentration (MIC) range, 0.125 to 4 μg/ml, MIC90 = 2 μg/ml). MIC90 values for the remaining five antibiotics were: doxycycline, 2 μg/ml; chloramphenicol, 8 μg/ml; ciprofloxacin, 8 μg/ml; clindamycin, 16 μg/ml; and gentamicin, 32 μg/ml. The effect of pH and/or media components on MICs was evaluated by comparing MICs of American Type Culture Collection reference strain Staphylococcus aureus 29213 obtained in Mueller-Hinton broth (pH 7.2 to 7.4) and 10B broth (pH 6.0). No appreciable effect was detected for ciprofloxacin, chloramphenicol or doxycycline, whereas gentamicin, erythromycin and clindamycin all had MICs elevated by one to several dilutions when tested in 10B broth. In some instances the difference was sufficient to alter the interpretation of the MIC. Clinical experience in treating neonatal ureaplasmal infections is reviewed along with recommendations for obtaining cultures, initiating and monitoring efficacy of therapy.

Pathogenesis and Significance of Urogenital Mycoplasmal Infections

U. urealyticum and M. hominis can no longer be considered as harmless commensals of the lower genitourinary tract. Both can produce disease in humans. Diagnosis and management of infections due to these organisms must be based upon isolation of the organisms from the affected site and preferably the number of organisms present. Due to the frequent resistance of both organisms to tetracycline, treatment must be based upon appropriate antibiotic sensitivities. For a more detailed description of the basic biology of these organisms and isolation and identification and treatment, the reader is referred to several recent reviews.