Actualités sur les infections à Legionella

Increasing Detection of Legionnaires' Disease in a Large Italian Hospital in the Period 2016-2023

The pandemic marked the beginning of an era of dynamic and rapid changes in the diagnosis of respiratory infections. Herein we describe Legionnaires' disease trend in the years 2016-2023 in a large Italian hospital showing how improvements in diagnostic algorithms impact on its detection.

Diagnosis and Surveillance of Neonatal Infections by Metagenomic Next-Generation Sequencing

Microbial infections cause significant morbidity and mortality in neonates. Metagenomic next-generation sequencing is a hypothesis-free and culture-free test that enables broad identification of pathogens and antimicrobial resistance genes directly from clinical samples within 24 h. In this study, we used mNGS for etiological diagnosis and monitoring the efficacy of antibiotic treatment in a cohort of neonatal patients with severe infections. The median age was 19.5 (3–52) days, median gestational age was 37.96 (31–40⁺³) weeks, and the median birth weight was 3,261 (1,300–4,300) g. The types of infectious diseases included pneumonia, sepsis, and meningitis. mNGS reported microbial findings in all cases, which led to changes in antibiotic treatment. These included cases of Mycobacterium tuberculosis, Legionella pneumophila, and Bacillus cereus. Eight of ten infants recovered after antibiotic adjustment and showed normal development during follow-up. On the other hand, neurological retardation was seen in two infants with meningitis. mNGS enabled etiological diagnosis and guided antibiotic therapy when all conventional methods failed to discover the culprit. It has the potential to cut down the overall cost and burden of disease management in neonatal infections.

Comparative study of Legiolert with ISO 11731-1998 standard method-conclusions from a Public Health Laboratory

BACKGROUND

Legionella pneumophila (L. pneumophila) is responsible for 96% of Legionnaires' disease (LD) and 10% of all worldwide pneumonia cases. Legiolert™, a liquid culture method for most probable number (MPN) enumeration of L. pneumophila, was developed by IDEXX Laboratories. The method detects all serogroups of L. pneumophila in potable and non-potable water samples.

OBJECTIVE

The goal of this study is to establish that Legiolert is a suitable alternative method to meet testing requirements in Spain for the enumeration of Legionella in water samples.

METHODOLOGY

The laboratory analyzed 118 environmental water samples from the Barcelona region (56 potable and 62 non-potable) in parallel by the Standard method for detection and enumeration of Legionella (ISO 11731:1998) and by Legiolert. Comparison of the recovery of the alternative method (Legiolert) and the Standard was made using ISO 17994:2014 and McNemar's binomial test statistical methods.

RESULTS

44 samples were positive for Legionella (36 potable and 8 non-potable). Legiolert and the Standard method detected a similar percentage of positive samples, with Legiolert being slightly higher (31 vs 30%) and detecting higher concentrations of Legionella within the samples. ISO 17994:2014 analysis of the potable water samples found Legiolert was more sensitive than the Standard at detecting Legionella, even when complete Legionella species (L. spp.) results were considered for both methods. The two methods also demonstrated equivalent detection of L. spp. according to the McNemar's test. The comparison is significantly more in favor of Legiolert when only L. pneumophila results are considered. Each confirmation run with material extracted from positive Legiolert wells contained L. pneumophila, giving the method a specificity of 100%. Although statistical results for non-potable waters are not included because of the low number of samples, the two methods trended towards equivalence.

CONCLUSIONS

Relative to the Standard method, Legiolert has a greater sensitivity and selectivity, and appears to have higher recovery for L. pneumophila, and equivalent recovery when L. spp. is included in the comparison. Legiolert also has high specificity. The procedural advantages of Legiolert allow laboratories to save on resources, costs, and time and consequently to test more frequently. In conclusion, the study finds IDEXX Legiolert a suitable alternative to ISO 11731:1998.