Ghislaine Descours

MACROLIDE-RESISTANT BORDETELLA PERTUSSIS INFECTION IN NEWBORN GIRL, FRANCE

A macrolide antimicrobial drug was administered to a newborn with cough. On day 23 of hospitalization, macrolide-resistant Bordetella pertussis was isolated from nasopharyngeal aspirates. DNA sequencing and PCR–restriction fragment length polymorphism showed a 2047 A-to-G mutation in the 3 copies of the 23S rRNA gene. Monitoring for macrolide resistance is essential in infants <6 months of age.

Identification of legionella in clinical samples.

Currently, several methods are used for the detection of Legionella in clinical samples, and these methods constitute part of the criteria for defining legionellosis cases. Urinary antigen detection is the first-line diagnostic test, although this test is limited to L. pneumophila serogroup 1 (Lp1) (Helbig et al., J Clin Microbiol 41:838-840, 2003). The use of molecular techniques can improve Legionaires disease (LD) diagnosis by detecting other serogroups and species (Diederen et al., J Clin Microbiol 46:671-677, 2008). The isolation of Legionella strains from pulmonary samples by axenic culture is still required to perform further epidemiological investigations (Blyth et al., N S W Public Health Bull 20:157-161, 2009; Fields et al., Clin Microbiol Rev 15:506-526, 2002) but demonstrates various sensitivities. Amoebic coculture has been described as a method to recover Legionella from clinical culture-negative specimens (La Scola et al., J Clin Microbiol 39:365-366, 2001; Rowbotham, J Clin Pathol 36:978-986, 1983) and can be proposed for optimizing Legionella strain isolation from samples contaminated by oropharyngeal flora. Identification of Legionella isolates is based on serological characterization, genotypic methods (with sequencing of the mip gene as the standard method) and, more recently, the Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) method.This chapter is limited to the identification of Legionella in clinical samples; antibody detection in human serum will not be discussed.

Evaluation of BMPA, MWY, GVPC and BCYE media for the isolation of Legionella species from respiratory samples☆

Culture media performance is a critical factor in the isolation of Legionellae from respiratory samples. We showed that BMPA and MWY media yielded significantly higher isolation rates than GVPC and BCYE media in regard to performance with samples that harbored low Legionella inocula and high contamination levels.

Contribution of Amoebic Coculture to Recovery of Legionella Isolates from Respiratory Samples: Prospective Analysis over a Period of 32 Months

ABSTRACT We evaluated the contribution of amoebic coculture to the recovery of Legionella spp. from 379 respiratory samples. The sensitivity of axenic culture was 42.1%. The combination of axenic culture with amoebic coculture increased the Legionella isolation rate to 47.1%. Amoebic coculture was particularly efficient in isolating Legionella spp. from respiratory samples contaminated with oropharyngeal flora.

Reassessment of the Role of Rapid Antigen Detection Tests in Diagnosis of Invasive Group A Streptococcal Infections

ABSTRACT Rapid antigen detection tests (RADTs) for group A streptococci (GAS) are widely used for diagnosing acute pharyngitis, which has led to a considerable reduction in antibiotic prescriptions over the past decade. Beyond this intended use, their reassessment on invasive samples may be relevant in the management of life-threatening GAS infections. To this end, we evaluated the performances of three RADTs, culture, GAS PCR, and 16S rRNA gene PCR assays, and compared them with a composite gold standard (GAS-PCR assay and/or culture) for the diagnosis of severe GAS infection. A total of 192 specimens from deep-tissue (mostly normally sterile) sites enriched for 75 GAS-positive samples were enrolled in the study. The three evaluated RADTs showed sensitivities ranging from 88.0% to 94.7% versus 98.7% for GAS PCR, 84% for 16S rRNA gene PCR, and 77.3% for culture. The sensitivities of the ImmunoCard STAT! Strep A test (Meridian Bioscience) and the NADAL Strep A strip (Nal Von Minden) were similar to that of GAS PCR (P = 0.25 and 0.03, respectively) and higher than that of culture (P = 0.001 and 0.006, respectively), whereas the SD Bioline Strep A test strip (Standard Diagnostics) showed a performance similar to that of culture (P = 0.02). The three RADTs detected 10 distinct emm types, including a predominance of emm 1 (33.3%), emm 89 (10.6%), and emm 12 (7.6%). No false-positive results were observed, leading to a specificity of 100% for all the evaluated RADTs. The GAS RADTs turned out to be sensitive, specific, and easy-to-use tools that may aid in the management of invasive GAS infections in 24/7 point-of-care laboratories by enabling early diagnosis and focused therapy.

It sounds like a relapsing polychondritis

A 9-year-old girl was referred for paediatric rheumatology consultation with a suspected diagnosis of relapsing polychondritis, a rare autoimmune disease aff ecting hyaline cartilages. The girl had presented during the previous 2 months with a painful red and swollen left ear without contralateral lesions (fi gure, A, B). Examination revealed no aphthous stomatitis, dyspnoea, joint pain, weight loss, or fever, and the external ear canal was not changed. With regards to the most commonly aff ected sites of relapsing polychondritis, the patient did not have infl ammation of the nasal septum, peripheral joints, or larynx. Notably, the earlobe was aff ected leading to a reconsideration of the diagnosis because relapsing polychondritis usually spares the earlobe. A biopsy sample was taken, which showed an infl ammatory perichondrial infi ltrate (fi gure, C). 16S rDNA PCR revealed an infection by Borrelia sp and a species-specifi c PCR identifi ed Borrelia garinii. The patient did not recall ever having had a tick bite. The patient recovered after a 4 week course of amoxicillin, and was asymptomatic after 1 year of follow-up. B garinii is one of the three major European species of borrelia and causes Lyme disease. Borrelia lymphocytoma is a less common manifestation within the range of skin diseases associated with this genus of bacteria, and is a tumour-like nodule that typically occurs in the earlobe, nipple, or scrotum. Ear perichondritis can occur, and earlobe affl iction rules out a diagnosis of relapsing polychondritis.

Legionella pneumophila LPS to evaluate urinary antigen tests

Three urinary antigen tests were compared using purified Legionella pneumophila (Lp) LPS. For Lp serogroup1, Sofia®FIA and Binax®EIA limits of detection (LOD) were similar; that of BinaxNOW® lower. For all tests the LOD was higher with LPS from non-Pontiac compared to Pontiac-strains. The LOD was variable for other Lp serogroups.