Correlation of Culture Positivity, PCR Positivity, and Burden of Borrelia burgdorferi Sensu Lato in Skin Samples of Erythema Migrans Patients with Clinical Findings.

BACKGROUND: Limited data are available regarding the relationship of Borrelia burden in skin of patients with erythema migrans (EM) and the disease course and post-treatment outcome. METHODS: We studied 121 adult patients with EM in whom skin biopsy specimens were cultured and analyzed by quantitative PCR for the presence of Borreliae. Evaluation of clinical and microbiological findings were conducted at the baseline visit, and 14 days, 2, 6, and 12 months after treatment with either amoxicillin or cefuroxime axetil. RESULTS: In 94/121 (77.7%) patients Borrelia was detected in skin samples by PCR testing and 65/118 (55.1%) patients had positive skin culture result (96.8% B. afzelii, 3.2% B. garinii). Borrelia culture and PCR results correlated significantly with the presence of central clearing and EM size, while Borrelia burden correlated significantly with central clearing, EM size, and presence of newly developed or worsened symptoms since EM onset, with no other known medical explanation (new or increased symptoms, NOIS). In addition, the logistic regression model for repeated measurements adjusted for time from inclusion, indicated higher Borrelia burden was a risk factor for incomplete response (defined as NOIS and/or persistence of EM beyond 14 days and/or occurrence of new objective signs of Lyme borreliosis). The estimated association between PCR positivity and unfavorable outcome was large but not statistically significant, while no corresponding relationship was observed for culture positivity. CONCLUSIONS: Higher Borrelia burden in EM skin samples was associated with more frequent central clearing and larger EM lesions at presentation, and with a higher chance of incomplete response.

Improvement of pneumococcal pneumonia diagnostics by the use of rt-PCR on plasma and respiratory samples.

BACKGROUND: The aim of the study was to assess the performance of a real-time polymerase chain reaction (rt-PCR) assay on plasma and respiratory samples for the diagnosis of pneumococcal pneumonia. METHODS: Three hundred and forty patients (160 children and 180 adults) with community-acquired pneumonia were included prospectively from January 2011 to May 2012. Blood samples were obtained simultaneously for culture and rt-PCR targeting the lytA gene. Respiratory samples were also obtained: nasopharyngeal swab in nearly all patients and sputum or tracheal aspirate when available. RESULTS: Streptococcus pneumoniae was detected in 222 (65%) of 340 patients: 143 (89%) children and 79 (44%) adults. Pneumonia was assigned as definite pneumococcal in 96 (28.2%) of 340 patients, according to S. pneumoniae detected in blood: in 54 (33.8%) children - by rt-PCR in 51 (31.9%) and by culture in 5 (3.1%); and in 42 (23.3%) adults - by rt-PCR in 41 (22.8%) and by culture in 12 (6.7%). Pneumonia was considered as probably pneumococcal in 19 (10.6%) adults according to S. pneumoniae detected in sputum/tracheal aspirate, by rt-PCR in 19 and by culture in 5. In 18 adults and 89 children with S. pneumoniae detected only in the nasopharynx, pneumonia was considered as possibly pneumococcal; however it should be noted that nasopharyngeal colonization with S. pneumoniae is also common in children with other aetiologies of pneumonia. CONCLUSIONS: rt-PCR on plasma and other samples performed significantly better than culture for the detection of pneumococcal pneumonia (p < 0.0005) in children and adults.