We have described a gene coding for an Enterobacter cloacae protein, provisionally called OmpX (J. Stoorvogel, M. J. A. W. M. van Bussel, J. Tommassen, and J. A. M. van de Klundert, J. Bacteriol. 173:156-160, 1991). In the work reported here, OmpX was localized in the cell envelope by means of sucrose gradient fractionation of membrane vesicles. Overproduction of OmpX in Escherichia coli from a multicopy plasmid resulted in a reduction in the amount of OmpF. No accumulation of OmpF, of its uncleft precursor, or of its degradation products could be detected in various cell fractions by Western immunoblot analysis using monoclonal antibodies produced in response to OmpF. A decrease in the rate of synthesis of ompF mRNA was indicated by a beta-galactosidase assay in an ompF-lacZ fusion strain containing the cloned ompX gene and by Northern (RNA) blot analysis. These results indicate that the inhibition is at the level of transcription. Colony hybridization, using an internal ompX fragment as a probe, showed a widespread distribution of the ompX gene among clinical isolates of members of the family Enterobacteriaceae. To study the function of the OmpX protein and its role in the regulation of porin protein synthesis, the ompX gene was deleted from the Enterobacter cloacae chromosome and replaced by the aphA gene. The absence of the ompX gene had no apparent effect on cell growth or on the regulation of the porin proteins.

Quantitation of herpes simplex virus (HSV) DNA in bronchoalveolar lavage specimens could indicate an infectious role in the lower respiratory tract. The aim of this study was to compare quantitative HSV DNA results from adult bronchoalveolar lavage specimens to clinical outcome. Quantitative real-time PCR assays targeting HSV and other herpes viruses were performed on adult bronchoalveolar lavage specimens obtained from a largely immunocompromised population during a 1-year period. The results were compared to patient characteristics and outcome. HSV DNA was detected in 11 (19%) of 57 bronchoalveolar lavage specimens with a mean viral level of 5.6 log genome equivalents/ml (range, 2.9-8.1 log). A threshold of HSV DNA levels equal or higher than 5.0 log (n = 7) was associated with mortality within 28 days following hospital admission (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.2-39.2). A threshold level of 5.5 log was associated with mortality within 28 days of sampling (OR 8.5; 95% CI 1.2-62.1), only after excluding patients receiving specific antiviral medication. Patients with HSV DNA levels equal or higher than 7.5 log had severe respiratory failure. Viral pneumonia was histologically proven in one patient with 8.0 log at autopsy. No patient with HSV DNA levels below 5.5 log (n = 5) or DNA levels higher than 5.0 log of cytomegalovirus (CMV) (n = 3), Epstein-Barr virus (EBV) (n = 9), varicella-zoster virus (VZV) (n = 1), or human herpesvirus 6 (HHV-6) (n = 0) died within 28 days of hospital admission. We conclude that quantitative detection of HSV DNA in bronchoalveolar lavage fluid is a potential diagnostic tool for detection of relevant viral infection of the lower respiratory tract.