Susceptibility of Legionella pneumophila to antimicrobial agents and the presence of the efflux pump LpeAB.

OBJECTIVES: Legionella pneumophila strains resistant to antimicrobial agents are rare. We tested 10 antimicrobial agents against clinical and environmental strains and performed WGS to screen for the presence of resistance mechanisms. METHODS: A total of 122 clinical and environmental strains of L. pneumophila collected between 2000 and 2017 and characterized by serogroup and ST were included. Antimicrobial susceptibility was tested by gradient diffusion tests on buffered charcoal yeast extract agar medium supplemented with α-ketoglutarate (BCYE-α) and a subgroup of strains were whole-genome sequenced using Illumina technology and analysed. RESULTS: All strains showed a WT MIC distribution for ciprofloxacin, levofloxacin, moxifloxacin, rifampicin, cefotaxime, tetracycline and trimethoprim/sulfamethoxazole. All strains of L. pneumophila serogroup 1, ST1 (18/122; 14.7%) showed reduced susceptibility to azithromycin (MIC 0.5-1 mg/L) and harboured the efflux pump component lpeAB. Two strains of L. pneumophila serogroup 5 (ST1328) and one strain of serogroup 4 (ST1973) also showed reduced susceptibility to azithromycin (MIC 0.5 mg/L). They harboured lpeAB gene variants with 91.37% and 92.52% nucleotide identity, respectively, compared with the lpeAB genes of serogroup 1, ST1 strains. CONCLUSIONS: Our collection of L. pneumophila strains was susceptible to most antimicrobial agents except azithromycin. Gradient diffusion tests on BCYE-α test medium detected strains with reduced susceptibility to azithromycin. All L. pneumophila serogroup 1, ST1 strains showed reduced susceptibility to macrolides and contained the efflux pump component lpeAB. Reduced susceptibility to azithromycin in non-serogroup 1 strains may be due to the presence of an lpeAB efflux pump variant.

Lyme meningitis, the major cause of childhood meningitis in an endemic area: a population based study.

OBJECTIVE: To evaluate the epidemiology of infectious meningitis in children in a Lyme borreliosis (LB) endemic area, and to study how clinical and laboratory characteristics may distinguish between different types of childhood meningitis. DESIGN: Retrospective, population based study. SETTING: A paediatric department serving all children (62 000) in a costal LB endemic region of southwestern Norway. PATIENTS: All children with cerebrospinal fluid pleocytosis aged 3 months to 14 years. MAIN OUTCOME MEASURES: Epidemiological, clinical and laboratory characteristics of different types of childhood meningitis. RESULTS: Infectious meningitis was diagnosed in 211 children (annual incidence 38/100 000). Lyme meningitis (LM) was identified in 142 children (67%), non-Lyme aseptic meningitis in 46 children (22%) and bacterial meningitis in 23 children (11%). Age, month of admission and clinical and laboratory characteristics differed between the groups. An aetiological agent was found in 89% of children. The positive predictive value for having LM if the child had facial nerve palsy or head and/or neck stiffness (meningism) as the only symptom was 97% for both variables. Symptoms of cerebral involvement or signs of systemic inflammation were rare in children with LM compared to children non-Lyme aseptic meningitis. CONCLUSION: LM was diagnosed in two-thirds of children with infectious meningitis in this LB endemic area. Distinct clinical characteristics distinguished the majority of children with LM from children with non-Lyme aseptic meningitis and bacterial meningitis.