No abstract

Mycoplasma pneumoniae infection was diagnosed in 18 (12.5%) of 144 adults hospitalized with communityacquired pneumonia. The infection was demonstrated by PCR in 15 patients and by serology, using two methods, in 10 patients. The mean age of the 8 patients with positive M. pneumoniae PCR and negative serology was significantly higher than that of the 10 patients with positive serology.

To determine the susceptibility of AMPLICOR Chlamydia trachomatis PCR to inhibitory factors possibly present in cervical specimens, we obtained cervical specimens from 200 gynecology patients attending our outpatient clinic. The prevalence of C. trachomatis infection was 4.1%, as determined by cell culture. All AMPLICOR specimens were tested in one procedure as described by the manufacturer, and after the specimen was spiked with C. trachomatis, several other pretreatment protocols were used. Complete inhibition of the PCR was observed in 38 (19%) cervical specimens. Heat treatment at 95؇C, freeze-thawing, or 10-fold dilution of the samples reduced the initial inhibition to 9, 16, or 9%, respectively. A combination of heat treatment and 10-fold dilution reduced the inhibition to 4% of the samples. A second specimen type (swabs inoculated in 0.2 M sucrose phosphate buffer [2SP]) was also evaluated. A 10-fold dilution of the spiked 2SP specimens resulted in an inhibition rate of 6%, which was comparable to that obtained by centrifugation of the 2SP specimen prior to processing. Furthermore, it was shown that the inhibition was not correlated with blood contamination. Processing the specimens on the day of collection or the day after resulted in a higher inhibition rate than did delayed processing (27.6 versus 15.5%, respectively). An inverse correlation was found between the concentration of C. trachomatis added to the sample and the rate of inhibition observed. The inhibition was partly correlated with the pH of the cervical mucosa. Decreased inhibition was found at pH values of >7.5. The effects of blood, pH, and delay in processing were all evaluated by using the AMPLICOR specimen. We conclude that the susceptibility of AMPLICOR C. trachomatis PCR to inhibiting factors in cervical specimens can be significantly reduced if the pretreatment procedure includes heat treatment or the use of 2SP transport medium. Also, a 10-fold dilution of the clinical specimen followed by heat treatment will largely prevent the inhibition of this PCR.

We prospectively studied 156 patients with a diagnosis of community-acquired pneumonia requiring admission. Several respiratory specimens were obtained for the detection of Chlamydia pneumoniae by cell culture and PCR. Three serum samples were obtained from each patient. Serological diagnosis of a C. pneumoniae infection was determined by the microimmunofluorescence (MIF) test, the complement fixation (CF) test, and recombinant lipopolysaccharide (LPS) enzyme-linked immunosorbent assay (ELISA; referred to as the rDNA LPS ELISA). Twenty-three patients (15%) had serological results compatible with acute C. pneumoniae infection; nine (39%) of these subjects were C. pneumoniae PCR positive. Twenty-two patients (14%) had positive PCR results without serological evidence of an acute C. pneumoniae infection. An attempt was made to calculate the sensitivities and specificities of the MIF test, rDNA LPS ELISA, and PCR for the diagnosis of chlamydial community-acquired pneumonia. Several “gold standards” were defined. Generally, the sensitivities of the rDNA LPS ELISA and MIF were comparable, while the sensitivity of the CF test was shown to be very low. Independent of the gold standard used, the best PCR results were obtained with nasopharyngeal specimens. However, the predictive value of a positive C. pneumoniaePCR result for patients with community-acquired pneumonia remains unknown and may be low. Although a widely accepted gold standard is still lacking, the rDNA LPS ELISA may currently be the preferred tool for diagnosing acute respiratory Chlamydia infections in routine clinical practice. However, the MIF test remains the method of choice for determining the prevalence of C. pneumoniaeinfections in a given community.

BACKGROUND. Chlamydia trachomatis is the most common sexually transmitted pathogen in adults, which at delivery may be transmitted from mother to child and cause conjunctivitis and pneumonia. In the Netherlands, prenatal chlamydial screening and treatment of pregnant women is not routine practice. The contribution of C trachomatis to neonatal ophthalmic disease has not been studied in the Netherlands and remains unclear.