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The Chemistry of O-Polysaccharide Chains in Bacterial Lipopolysaccharides
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
The O-polysaccharide from P. mirabilis type 010 (43,44) contains altruronic acid, which has the l-con-figuration, as demonstrated by the use of 13C-NMR glycosylation shifts. The chemical shift of the C-1 signal of the uronic acid was only compatible with a different absolute configuration than that of the D-GalNAc, to which it was linked. Unlike altrose it was found in a conformation close to that of 4C1. The conformation also differed from that of the altruronic acid found in the capsular polysaccharide of Aerococcus viridans var. homari. The acid was suggested to derive biosynthetically from d-galacturonic acid (d-GalA). Types 026 (45,46) and 028 (47) have closely related structures with galacturonic acids amidated with the amino acids lysine (026) or serine and lysine (028). The 028 O-chain has amides on both GalA residues. The importance of GalA-Lys as an immunodominant factor was demonstrated using synthetic glycopolymers made from 2-acrylamidoethyl glycosides of amides of GalA (47). P. mirabilis 043 (48) cross-reacts with 010, and both contain a GalA residue. Periodate oxidation of 043, which destroys two of the four residues, results in loss of serological activity as determined by precipitation and inhibition assays. It was also noted that the level of negative charges was high: two charges per four sugar residues. P. mirabilis 030 (45) is a linear hexosaminoglycuronan. As an aid in the structural determination computer-assisted analysis of the 13C-NMR chemical shifts was made, and the NMR spectrum was compatible with only one linear sequence. The O-chain of P. mirabilis serotype 023,56 [strain 7570 (49)] contains two GalA residues, thus resembling 026 and 028 but none of them with an amide. The O-antigen of the mutant R14/1959, called the T-antigen (50), is identical to that of strain P. penneri strain 42. More correctly it should be called T-like antigen as T-forms do not carry any normal O-antigen.
Linezolid
Published in M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson, Kucers’ The Use of Antibiotics, 2017
Linezolid retains good in vitro activity against less commonly encountered Gram-positive organisms, including non-group A or B beta-hemolytic streptococci, viridans group streptococci, corynebacteria, Bacillus spp., and L. monocytogenes (Jones et al., 2007c). In the study by Jones et al. (2007c), only one isolate of the 3251 isolates tested was found to be linezolid-resistant. This was a linezolid-resistant Streptococcus oralis isolate containing the G2576T mutation (see later under 2b. Emerging resistance and cross-resistance). For enterococci other than E. faecalis and E. faecium, the MIC90 is higher (at 2 mg/l); however, it is still susceptible (Jones et al., 2007c; Lu et al., 2012). For most viridans group streptococci the MIC90 is 1–2 mg/l (see Table 73.1); however, higher MIC90 results were found for some viridans group streptococci (S. bovis and S. anginosus; MIC90 4 mg/l, MIC range 1–4 mg/l) in a study of a smaller number of isolates (Kosowska-Shick et al., 2006). A study of group B streptococci (S. agalactiae) using Etest susceptibility found an MIC90 of 1.5 mg/l and an MIC range of 0.25–1.5 mg/l (Fluegge et al., 2004). Against a large number of neonatal invasive isolates of S. agalactiae, linezolid demonstrated good activity when tested by Etest (MIC90 1.5 mg/l, range 0.25–1.5 mg/l) (Fluegge et al., 2004), whereas 106 maternal anovaginal screening isolates were all susceptible, including macrolide- and clindamycin-resistant isolates (Panda et al., 2009). Erythromycin-resistant strains of Streptococcus pyogenes and S. agalactiae had identical MIC patterns to erythromycin-susceptible strains (MIC90 2 mg/l) (Betriu et al., 2000). Helcococcus kunzii has been reported to be linezolid-susceptible (MIC90 2 mg/l, range 1–2 mg/l) (Vergne et al., 2015). Aerococcus urinae also appears generally susceptible, with only 2 of 95 tested isolates proving resistant in a recent study (modal MIC 1 mg/l, range ≤ 0.5–8 mg/l) (Humphries and Hindler, 2014). Linezolid is also active against the oral commensal Stomatococcus mucilaginosus (MIC range 1–2 mg/l) (Rolston et al., 2013) and the skin commensal Kytococcus schroeteri (MIC 0.19–1 mg/l) (Blennow et al., 2012).
Aerococcus urinae tricuspid valve infective endocarditis
Published in Baylor University Medical Center Proceedings, 2022
Sanchari Banerjee, Sindhubarathi Murali, Atika Azhar, Anojan Pathmanathan, Debanik Chaudhuri
A. urinae is an alpha-hemolytic, gram-positive coccus that grows in pairs or clusters.9 It can be misidentified as Staphylococcus or Streptococcus for its morphological similarities, or Enterococcus due to similar resistance patterns. As a result, the frequency of Aerococcus infection is significantly underestimated.10,11 Sequencing of the gene encoding 16S ribosomal ribonucleic acid remains the gold standard to identify the species. Unfortunately, the use of gene sequencing is limited due to its high cost; hence, it has been replaced with matrix-assisted laser desorption ionization time-of-flight mass spectrometry.12,13
Aerococcus urinae: an underestimated cause of spine infection? Case report and review of the literature
Published in Acta Clinica Belgica, 2018
Elodie Degroote, Halil Yildiz, Frederic Lecouvet, Alexia Verroken, Leila Belkhir
Aerococcus urinae is a Gram-positive bacteria mainly responsible for urinary tract infections (UTI) but it is also involved in invasive infections (e.g. infective endocarditis, bacteremia) frequently originating from a simple UTI [1,2]. The three Aerococcus species mostly responsible for human infections are A. viridans, A. urinae , and A. sanguinocola. Other Aerococcus species as A. christensenii, A. vaginalis (isolated from beef cow), A. urinae hominis, A. urinae equi (isolated from horses) , and A. suis (isolated from pigs) have also been described but their pathogenic role in humans still remains uncertain.
Surveillance of antimicrobial resistance and evolving microbial populations in Vermont: 2011-2018
Published in Expert Review of Anti-infective Therapy, 2020
John Stelling, Jennifer S. Read, William Fritch, Thomas F. O’Brien, Rob Peters, Adam Clark, Marissa Bokhari, Mattia Lion, Parisha Katwa, Patsy Kelso
By linear regression, organisms with a statistically significant increase (p < 0.05, no control for multiple comparisons) in the outpatient setting over the eight years include Aerococcus urinae., Helicobacter pylori, Peptostreptococcus sp, and Staphylococcus pseudintermedius. Among inpatients, statistically significant (p < 0.05) increases were seen in Klebsiella pneumoniae, Klebsiella aerogenes, Haemophilus influenzae, and both Group A and Group B beta-hemolytic streptococci, among others.