Moraxella lacunata Subacute Osteomyelitis in a Child

Characterization of two novel colistin resistance gene mcr-1 variants originated from Moraxella spp

This study aimed to characterize two novel mcr-1 variants, mcr-1.35 and mcr-1.36, which originated from Moraxella spp. that were isolated from diseased pigs in China. The Moraxella spp. carrying novel mcr-1 variants were subjected to whole-genome sequencing (WGS) and phylogenetic analysis based on the 16S rRNA gene. The mcr-1 variants mcr-1.35 and mcr-1.36 were characterized using phylogenetic analysis, a comparison of genetic environments, and protein structure prediction. The WGS indicated that two novel mcr-1 variants were located in the chromosomes of three Moraxella spp. with a genetic environment of mcr-1-pap2. In addition to the novel colistin resistance genes mcr-1.35 and mcr-1.36, the three Moraxella spp. contained other antimicrobial resistance genes, including aac(3)-IId, tet(O), sul2, floR, and bla_ROB-3. A functional cloning assay indicated that either the mcr-1.35 or mcr-1.36 gene could confer resistance to colistin in Escherichia coli DH5α and JM109. The nucleotide sequences of mcr-1.35 and mcr-1.36 presented 95.33 and 95.33% identities, respectively, to mcr-1.1. The phylogenetic analysis showed that mcr-1.35 and mcr-1.36 were derived from Moraxella spp. that belonged to subclades that were different from those of the mcr-1 variants (mcr-1.1 to mcr-1.34 except mcr-1.10) originating from Enterobacteriaceae. The deduced amino acid sequences of MCR-1.35 (MCR-1.36) showed 96.67% (96.49%), 82.59% (82.04%), 84.07% (83.52%), 55.52% (55.17%), 59.75% (59.57%), and 61.88% (61.69%) identity to MCR-1.10, MCR-2.2, MCR-6.1, MCR-LIN, MCR-OSL, and MCR-POR, respectively, that originated from Moraxella sp. Notably, protein structure alignment showed only a few changes in amino acid residues between MCR-1.1 and MCR-1.35, as well as between MCR-1.1 and MCR-1.36. In conclusion, this study identified Moraxella spp. carrying two novel mcr-1 variants, mcr-1.35 and mcr-1.36, conferring resistance to colistin, which were isolated from pig farms in China. In addition, mcr-like variants were observed to be located in the chromosomes of some species of Moraxella isolated from pig samples.

Infective Endocarditis by Moraxella Species: A Systematic Review

Moraxella catarrhalis is the most clinically relevant species among Moraxella spp. For decades, it was considered to be part of the normal human flora in the upper respiratory tract. However, since the late 1970s, considerable evidence has proposed that M. catarrhalis is an important pathogen in the human respiratory tract. Even though Infective Endocarditis (IE) is rarely caused by Moraxella spp., these infections can be problematic due to the lack of experience in their management. The aim of this study was to systematically review all published cases of IE by Moraxella spp. A systematic review of PubMed, Scopus and Cochrane library (through 8 December 2021) for studies providing epidemiological, clinical, microbiological data as well as treatment data and outcomes of IE by Moraxella spp. was performed. A total of 27 studies, containing data for 31 patients, were included. A prosthetic valve was present in 25.8%. Mitral valve was the most commonly infected site. Fever, sepsis and embolic phenomena were the most common clinical presentations. Cephalosporins, aminoglycosides, aminopenicillins and penicillin were the most commonly used antimicrobials. Overall mortality was 12.9%.

Eculizumab-Associated Moraxella lacunata Bacteremia and Systemic Inflammatory Response Syndrome in a Toddler with Atypical Hemolytic Uremic Syndrome

Moraxella lacunata, a low-virulence Gram-negative coccobacillus, is classically associated with conjunctivitis and upper respiratory tract infections; systemic infections such as sepsis have rarely been reported, especially in children. We describe a 28-month-old girl with atypical hemolytic uremic syndrome and stage II chronic kidney disease on long-term eculizumab therapy who presented with systemic inflammatory response syndrome and was found to have Moraxella lacunata bloodstream infection. Eculizumab, a humanized monoclonal anti-C5 antibody, has been associated with susceptibility to infections with encapsulated bacteria, especially Neisseria meningitidis. This is the first report of an invasive bacterial infection with Moraxella lacunata in a pediatric eculizumab recipient.