Antibacterial efficacy

Since the introduction of nalidixic acid in 1963, structural modifications on the quinolones have been performed to improve either the antibacterial efficacy or pharmacokinetic/toxicologic profiles of these compounds. The newest quinolones possess broad-spectrum activity, favorable pharmacokinetic/toxicologic profiles, and potency against bacterial strains that are resistant to older generations of quinolones. This section describes the synthetic procedures for the new generation of quinolones that were studied during the 1995-2005 period. 

Syntheses of naphthyridone derivatives follow the same procedures as those of quinolones, except that substituted 2-aminopyridines (Gould-Jacobs modification) or substituted nicotinic ester/nicotinoyl chloride are used instead of anilines or o-halobenzoic acid derivatives. Most of the recently introduced quinolone antibacterials possess bicyclic or chiral amino moieties at the C-7 position, which result in the formation of enantiomeric mixtures. In general, one of the enantiomers is the active isomer, therefore the stereospecific synthesis and enantiomeric purity of these amino moieties before proceeding to the final step of nucleophilic substitution at the C-7 position of quinolone is of prime importance. The enantiomeric purity of other quinolones such as ofloxacin (a racemic mixture) plays a major role in the improvement of the antibacterial efficacy and pharmacokinetics of these enan-... 

Webb MS, Boman NL, Wiseman DJ, et al. Antibacterial efficacy against an in vivo Salmonella typhimurium infection model and pharmacokinetics of a liposomal ciprofloxacin formulation. Antimicrob Agents Chemother 1998 42 45. 

Gindamydn has antibacterial activity similar to that of erythromycin. It exerts a bacteriostatic effect mainly on gram-positive aerobic, as well as on anaerobic pathogens. Gindamycin is a semisynthetic chloro analogue of lin-comycin, which derives from a Streptomyces species. Taken orally, clindamycin is better absorbed than lincomycin, has greater antibacterial efficacy and is thus preferred. Both penetrate well into bone tissue. 

Application of some kind of sample treatment may have the potential to improve substantially the detection of certain antibacterials in milk by microbial routine methods (59). Treatment, for example, of milk samples with ammonium oxalate solution prior to analysis can lead to lower limits of detection of tetracyclines by both microbial inhibition and microbial receptor assays. This is due to the fact that tetracycline residues tend to form chelates with divalent cations and bind to proteins, which reduce their antibacterial efficacy. However, the oxalate treatment causes splitting of complex and/or protein bonds without increasing the detection limits of other antibacterials commonly used in dairy cows. 

Antagonism in antibacterial efficacy between nitrofurantoin and nalidixic acid has been observed (93). 

Nonionic emulsifying wax is incompatible with tannin, phenol and phenolic materials, resorcinol, and benzocaine. It may reduce the antibacterial efficacy of quaternary ammonium compounds. 

The chemical composition of the base cream can alter the antibacterial effectiveness of azelaic acid Charnock C, Brudeli B, Klaveness J. Evaluation of the antibacterial efficacy of diesters of azelaic acid. Eur J Pharm Sci 2004 21(5) 589-96. 

PP/silver nanocomposite fibres were prepared with the aim of achieving permanent antibacterial activity in a common synthetic textile. The fibres were melt-spun by coextmsion of PP and PP/silver masteibatches using general conjugate spinning. Masteibatches were made up of a mixture of PP chips and nano-sized silver powder. The antibacterial efficacy of spun fibres was high when the masteibatch was used as the sheath rather than the core. The antibacterial activity of nano-silver in fibres was evaluated after a certain contact time and calculated by percent reduction of two types of bacteria. Staphylococcus aureus and Klebsiela pneumoniae. DSC and wide-angle X-ray diffraction were used for analysis of stractuie, thermal properties and crystallisation behaviour of the spun fibres. SEM was carried out in order to observe particle distribution on the nanocomposite fibres. 17 refs. (2nd International Conference on Polymer Fibres, Manchester, UK, July 2002)... 

The test methods discussed below are classified in five categories evaluation of cleaning performance evaluation of foam performance (volume and stability) evaluation of mildness evaluation of antibacterial efficacy and other tests. 

These differences are possibly due to variations in the experimental conditions of the various studies (e.g., ionic strength). Nevertheless, the antibacterial efficacy of softener actives under normal use conditions remains questionable. 

This is the mechanism proposed by Datyner to account for CTAC antibacterial, and antifungal to a lesser extent, activity he reports [20]. Martins et al. invoke the ability of the surfactant to disrupt the cell membrane and form mixed micelles with its lipids to account for CTAB and SLS antibacterial activity [29], In contrast, the bacteria-killing efficacy of double-chain surfactants such as DHTDMAC is assigned to an alteration of the membrane protein function resulting from the adsorption of vesicles onto the bacterial membrane. This study was carried out under laboratory conditions (very low ionic strength), and the antibacterial efficacy of fabric softeners under realistic use conditions remains highly questionable. 

Monitoring vancomycin serum concentrations is not cost-effective in preventing vancomydn-induced nephrotoxicity in patients with normal renal function, since the correlation between serum levels and antibacterial efficacy or toxicity remains controversial [185, 186, 182]. Serum level determination may be helpful in patients with increased volume of distribution, in patients with decreased renal function, in children or neonates, and in the elderly [165]. 

Finally, the researcher performs a clinical trial with human volunteer subjects to compare the two products antibacterial efficacy, as well as their skin irritation potential. Although the antimicrobial portion of the study had revealed activity equivalence, the skin irritation evaluation demonstrates that... 

W Sheikh. Comparative antibacterial efficacy of Hibiclens7 and Betadine7 in the presence of pus derived from human wounds. Cuff Ther Res 40 1096-1102, 1986. 

A study of the way the kidneys handle nitrofurantoin found that intravenous sulfinpyrazone 2.5 mg/kg reduced the secretion of nitrofurantoin by the kidney tubules by about 50%. Thi s reduction would be expected to reduce its urinary antibacterial efficacy, and the higher serum levels might lead to increased systemic toxicity, but there do not seem to be any reports suggesting that this represents a real problem in practice. The same situation would also seem likely with probenecid, but there do not appear to be any reports confirming this interaction. 

The clinical importance of both of these interactions is therefore uncertain, but it would seem prudent to be alert for any evidence of reduced antibacterial efficacy and increased systemic toxicity if either sulfinpyrazone or probenecid is used with nitrofurantoin. 

The emeraldine salt forms of copolymers appear to be more antimicrobially effective than the emeraldine base forms of the same copolymer. It seems that the presence of an acidic functional group (-COOH) in the polymer chain improves the antibacterial efficacy of the copolymer. This could, in theory, be due to the acidic dopants on the molecular chains of the copolymers reacting with the bacteria (or other relevant microbial organism) which result in microbial death. Alternatively, it could be due to the electrostatic adherence between copolymer molecules and the bacteria, which carry charges of different polarity, the bacteria walls may break and the bacterial contents become exposed or leak out, which cause the bacteria to die [17]. 

The antibacterial efficacy of Ppy deposited on cotton fabrics was quantitatively evaluated under dynamic contact conditions according to the American Society for Testing and Materials (ASTM), ASTM E2149-01. Moreover, the bactericidal mechanism of Ppy on Escherichia coli bacteria was preliminarily investigated [55]. 

Antibacterial efficacy decreased after non-ionic and anionic lanndering of the fabric. In particular, the antibacterial activity of Ppy(Cl) samples was severely degraded by anionic laundering. The antibacterial activity of Ppy has been investigated against Streptococcus pneumoniae (RCMB 010010), Enterococcus faecalis (RCMB 010068) and Staphylococcus aureus (RCMB 010028), i.e.. Gram-positive bacteria. The agar disc diffusion method was used to determine the antibacterial activity and ampicillin... 

The imparted antibacterial efficacy against G+ve and G-ve bacteria was attributed to capacity of thymol to destroy bacterial cells... 

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