Comparative in-vitro activity of quinolone carboxylic acids against Proteeae

Abstract

The in-vitro susceptibilities of 198 isolates of precisely identified Proteeae species to six quinolone antimicrobials were determined. Significant differences in susceptibility patterns among various Proteeae to the quinolones examined were demonstrated. Although Providencia stuartii was found to be the most resistant to quinolones including the very active agent ciprofloxacin, fully speciated Prov. rettgeri were also markedly resistant as well. in contrast Prov. alcalifaciens was extremely sensitive to these agents. Some strains of Proteus penneri were more resistant to the three newer compounds (ciprofloxacin, enoxacin and norfloxacin) than strains of Pr. vulgaris suggesting that recognition of this species may be important in surveys of the in-vitro activity of antibiotics. Pr. mirabilis and Morganella morganii were very sensitive to the newer agents. The patterns of resistance seen in the three newer agents were reflected in the older agents acrosoxacin and cinoxacin. Accurate speciation of Proteeae in surveys of susceptibilities to antimicrobial agents is important if misleading results are not to be reported.

In vitro activity of ciprofloxacin against aerobic bacteria isolated in a southern European hospital

“…Along with the low susceptibility of this species, we also found a higher susceptibility for P. rettgeri, and the combination of these two findings suggests the possibility that lower susceptibility to quinolones is a property peculiar to P. stuartii strains and not to P. rettgeri strains; in the previous studies some of the P. stuartii strains may have been erroneously identified as P. rettgeri and vice versa. As a possible confirmation of this, it is worth mentioning that a similar, albeit less evident, trend of susceptibility to quinolones among Providencia strains has been reported only once (12), in the only work that took into account, as we did, virtually all the main Providencia species, identified by the same up-to-date criteria that we used (4,9). We stress that these data are consistent with the well-known low susceptibility of P. stuartii strains to several other antimicrobial agents, as opposed to the other strains of the genus Providencia.…”

“…For instance, both the Providencia genus and enterococci species were fully identified in only one study each (7,12), and the susceptibility of all of the coagulase-negative staphylococcal species has not been previously reported (6,11). Moreover, the activity of ciprofloxacin against strains isolated from Southern Europe has been scarcely evaluated (18).…”

In Vitro and In Vivo Antimicrobial Activity of Antibiotic‐Conjugated Carriers with Rapid pH‐Responsive Release Kinetics

“…Because bacterial populations develop antibiotic resistance via selective pressure when exposed to antibiotics, we envisioned that the selective release of antibiotics at inflammatory or abscess sites could reduce the possibility of antibiotic resistance developing at nonpathogenic sites. At much higher concentrations (1.4 and 2.8 µg mL −1 ) than the initial MIC of free CP (0.70 µg mL −1 ) against S. aureus (strain ATCC 6538P), few bacteria survived for the next round of incubation (data not shown).…”

Biodegradable nitric oxide precursor-loaded micro- and nanoparticles for the treatment of Staphylococcus aureus biofilms

“…The increasing prevalence of Staphylococcus aureus (S. aureus) biofilm-associated infections such as skin and bone infections, 1,2 endocarditis, 3 sinus 4 and device-related infections (catheters, implantable prosthetics) 5,6 are placing significant burden on healthcare systems and society. 7 Biofilms are complex, functional communities of one or more species of microorganisms that are encased in extracellular polymeric substance (EPS) and are attached to both a solid surface and to each other. 8 The slow growth rates, 9 low antibiotic penetration, 10 high cell density, 11 excessive extracellular matrices, 12 pH alterations, 13 mutations 14 and altered nutrient requirements 15 are well-known properties that give rise to greater antimicrobial resistance in microbial biofilms.…”