Phylogenomic analysis of the understudied Neisseriaceae species reveals a poly- and paraphyletic Kingella genus.

IMPORTANCE: Understanding the evolutionary relationships between the species in the Neisseriaceae family has been a persistent challenge in bacterial systematics due to high recombination rates in these species. Previous studies of this family have focused on Neisseria meningitidis and N. gonorrhoeae. However, previously understudied Neisseriaceae species are gaining new attention, with Kingella kingae now recognized as a common human pathogen and with Alysiella and Simonsiella being unique in the bacterial world as multicellular organisms. A better understanding of the genomic evolution of the Neisseriaceae can lead to the identification of specific genes and traits that underlie the remarkable diversity of this family.

In vitro Activity of Ceftaroline Against an International Collection of Kingella kingae Isolates Recovered From Carriers and Invasive Infections.

BACKGROUND: Improvements in blood culture techniques and molecular-based diagnostics have led to increased recognition of Kingella kingae as an invasive human pathogen causing bacteremia, septic arthritis, osteomyelitis and endocarditis in young children. Serious disease and potentially life-threatening complications of infection due to K. kingae necessitate timely identification and appropriate antimicrobial therapy. Ceftaroline is a fifth-generation broad spectrum cephalosporin that possesses activity against Gram-negative and Gram-positive pathogens similar to third-generation cephalosporins, but also includes methicillin-resistant Staphylococcus aureus . This study reports the in vitro activity of ceftaroline and comparator agents against an international collection of K. kingae isolates. METHODS: A collection of 308 K. kingae isolates was obtained primarily from children with bacteremia, endocarditis, osteoarticular infections or from asymptomatic pediatric carriers. Isolates were tested for antibiotic susceptibility using Clinical and Laboratory Standard Institute broth microdilution methodology and screened for ß-lactamase production using a nitrocefin chromogenic test. RESULTS: Ceftaroline inhibited all K. kingae isolates at ≤0.06 mg/L (MIC 50/90 , 0.015/0.03 mg/L). Ceftaroline MICs were similar to results with ceftriaxone (MIC 50/90 , 0.015/0.015 mg/L), meropenem (MIC 50/90 , 0.015/0.015 mg/L) and ampicillin-sulbactam (MIC 50/90 , 0.06/0.06 mg/L). Ceftaroline MICs were slightly lower than MICs for cefuroxime and amoxicillin/clavulanate (MIC 50/90 , 0.06/0.12 mg/L). MICs were high for clindamycin (MIC 50/90 , 2/4 mg/L) and oxacillin (MIC 50/90 , 4/8 mg/L). Sixteen isolates (5.2%) yielded a positive nitrocefin test indicating production of ß-lactamase; ceftaroline demonstrated equivalent MICs against ß-lactamase - positive and ß-lactamase - negative strains (MIC 50/90 , 0.015/0.3 mg/L). CONCLUSIONS: The potent activity of ceftaroline against this large international collection of K. kingae isolates supports further clinical evaluation in children.