Natural antimicrobial susceptibilities of strains of 'unusual' Serratia species: S. ficaria, S. fonticola, S. odorifera, S. plymuthica and S. rubidaea

Abstract

The natural susceptibility to 71 antibiotics of 104 Serratia strains of Serratia ficaria (n = 15), Serratia fonticola (n = 18), Serratia odorifera (n = 16), Serratia plymuthica (n = 32) and Serratia rubidaea (n = 23) was examined. MICs were determined using a microdilution procedure in IsoSensitest broth for all the strains and in cation-adjusted Mueller-Hinton broth for some strains. With few exceptions, all species tested were uniformly naturally resistant to penicillin G, oxacillin, cefazolin, cefuroxime, all tested macrolides, lincosamides, streptogramins, glycopeptides, fusidic acid and rifampicin, and naturally sensitive to several aminoglycosides, piperacillin, piperacillin/tazobactam, carbapenems, some cephalosporins, fluoroquinolones and folate-pathway inhibitors. Major species-related differences in natural susceptibility affecting clinical assessment criteria were seen with tetracyclines, some aminoglycosides, aminopenicillins, ticarcillin, cefaclor, loracarbef, cefoxitin, pipemidic acid, chloramphenicol, nitrofurantoin and fosfomycin. Differences in susceptibility dependent on the medium were seen with macrolides, tetracycline, fosfomycin and some beta-lactams. The natural antibiotic susceptibility patterns suggest novel species-specific mechanisms of antibiotic resistance. Uncharacterized species-specific aminoglycoside-modifying enzymes and multidrug efflux systems affecting tetracyclines, quinolones and chloramphenicol are probably responsible for some of the phenotypes observed. The natural amoxicillin sensitivity of several strains of some species combined with natural resistance to some narrow-spectrum cephalosporins indicate the expression of naturally occurring beta-lactamases with unique substrate profiles. beta-Lactamases of representative strains of each species were characterized phenotypically and genotypically. It was shown that all species expressed naturally occurring AmpC beta-lactamases and, with respect to S. fonticola, also a species-specific class A beta-lactamase. Inducibility of these enzymes was shown in all species with the exception of S. rubidaea and four of five strains of S. plymuthica.

The Pepsin Hydrolysate of Bovine Lactoferrin Causes a Collapse of the Membrane Potential in Escherichia coli O157:H7

“…To reduce or eliminate the potential for interaction of LfH with the outer membrane, via LPS or porin channels, E. coli O157:H7 spheroplasts were used [20]. Spheroplasts are characterized by partial or complete loss of the outer membrane and lack of cell rigid structure [33,40]. Changes in cell morphology during development of E. coli O157:H7 spheroplasts were documented (data not shown).…”

Inhibition of Quorum Sensing Mediated Virulence Factors Production in Urinary Pathogen Serratia marcescens PS1 by Marine Sponges

“…It shows high resistance against a wide range of b-lactam, aminoglycoside and fluoroquinolone antibiotics and thereby makes the antibiotic treatment become ineffective [25,28]. Thus, the emergence of antibiotic resistance among bacterial pathogen necessitate the findings of alternative strategies to antibiotic treatment.…”

Isolation of a Novel Lipase Gene from Serratia liquefaciens S33 DB-1, Functional Expression in Pichia pastoris and its Properties

“…As one of genus Serratia, Serratia liquefaciens is frequently referred to causing the human nosocomial infections [7]. S. liquefaciens strain was studied as a candidate compound for the management of hypertriglyceridemia for producing a pharmacological effect of FR177391 due to its infectivity [8].…”