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N anoparticulate silver compounds (AgNP) have widespread use in antibacterial clothing, water filtration, coated medical devices, wound dressings, and cosmetics due to the versatility of nanoparticles and the established activity of silver against

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Abstract

Objective—To design short and potent analogs of bovine lactoferricin by use of the concepts of lipophilic bulk and cationic charge.

Sample Population—5 synthetic peptides of bovine lactoferricin.

Procedure—Antibacterial peptides were constructed by synthesizing several decapeptides rich in arginine and tryptophan. Basic residues of bovine lactoferricin (bLf 20-29; residues 20 to 29) were modified by substitution with arginine or lysine and nonbasic residues were modified by substitution with tryptophan, phenylalanine, or isoleucine. Synthetic peptides of bovine lactoferrin (LFB) were designated as LFB-RW (RRWWWRWRRW), LFB-KW (KKWWWKWKKW), LFB-RWa (RRWWRRWRRW), LFB-RF (RRFFFRFRRF), and LFB-RI (RRIIIRWRRI), where R, K, W, F, and I stand for arginine, lysine, tryptophan, phenylalanine, and isoleucine, respectively. Peptides were evaluated by determining their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli, Staphylococcus aureus,and Enterococcus faecalis.

Results—LFB-RW, LFB-KW, and LFB-RWa possessed equivalent potency as bLf 20-29 against E coli. LFB-RW and LFB-RWa had a 2-fold increase in growth-inhibitory and bactericidal activity against S aureus, compared with bLf 20-29. LFB-RI had the lowest MIC value against E coli among the peptides but lost bactericidal activity. LFB-RW and LFB-KW had stronger bactericidal activities against S aureus or E faecalis, respectively, as well as E coli than the other synthetic peptides. LFB-RF also had antibacterial activity, but this was 2-fold less than that of LFBRW, as determined by MIC and MBC values.

Conclusions and Clinical Relevance—In construction of potent antibacterial peptides, inclusion of arginine, lysine, tryptophan, or isoleucine residues enhances effectiveness against certain bacteria, as measured by MIC or MBC values. (Am J Vet Res 2003;64:1088–1092)

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in American Journal of Veterinary Research

indicated that, of the 4 treatments evaluated, NPWT-PVA had the greatest antibacterial effect against both P aeruginosa and MRSA. For wounds treated with NPWT-PVA, the bacterial load of P aeruginosa decreased significantly during the 24-hour observation

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in American Journal of Veterinary Research

Summary

Effect of estrogen (E2) and progesterone (P4) on uterine antibacterial activity and immunoglobulin concentrations in mares was studied. In 2 in vitro experiments, 6 mixed-breed mares were ovariectomized, and uterine fluid and blood serum were analyzed. Antibacterial assay methods were used to determine inhibitory effects on Streptococcus zooepidemicus of uterine fluid samples collected on days 3, 5, and 8, and serum obtained on day 8 of treatment. Single radial immunodiffusion methods were used to quantify amounts of IgA and IgG in uterine fluid and serum on days 3, 5, 8, and 14 of treatment. Neither E2 nor P4 increased activity of serum and uterine fluid against S zooepidemicus. Numbers of colony-forming units per milliliter of bacteria were significantly (P < 0.01) lower in control Hanks’ balanced salt solution with 1.0% gelatin (hbssg) than in uterine fluids. Bacterial numbers were significantly (50%) greater in uterine fluids and serum than in hbssg controls for both treatments. Both fluids, especially serum, supported significantly (P < 0.01) more growth of S zooepidemicus than did hbssg when incubated for 0, 2, and 4 hours. These findings are in contrast to previous reports of antibacterial activity in the uterus of sexually intact mares undergoing an estrous cycle: great reduction of bacterial count in uterine fluid from mares in diestrus, and significant increases in bacterial numbers in uterine fluid or serum from mares in estrus. Treatment comparisons between serum and uterine fluid IgA and IgG concentrations were not significantly different, although overall IgA concentration in the uterus was higher than concentration in serum. The IgG concentration in uterine fluid was higher in P4- than E2-treated mares. However, IgG concentration was significantly (P < 0.01) higher in uterine fluid on day 8 in P4-treated mares than on day 3 or 5. Results of this study indicate that neither immunoglobulin concentration nor hormone treatment has a direct effect on streptocidal activity.

Free access
in American Journal of Veterinary Research

SUMMARY

Prophylactic efficacy of 4 antibacterial shampoos against Staphylococcus intermedins in dogs was determined by use of a controlled quantitative technique. Ten adult Beagles were used in the study. The antibacterial agents in the shampoos were 3.0% benzoyl peroxide, 0.5% Chlorhexidine acetate, 1.0% available iodine as a polyalkyle-neglycol-iodine complex, and a combination of 0.5% triclosan, 2.0% sulfur, and 2.0% salicylic acid. Treated and control sites were challenge exposed with 5.30 ± 0.10 (log10) S intermedins colony-forming units (cfu)/cm2 of skin and occluded for 5 hours. At the end of the test period, remaining bacteria were removed with a detergent cup-scrub technique and the total number of S intermedins cfu/cm2 skin was calculated for each treated and control site.

Nontreated bacteria-challenged control sites yielded 5.62 ± 0.65 S intermedins cfu/cm2 of skin. Staphylococcus intermedins recovery (cfu/cm2) from the treated sites was 0.94 ± 0.76 for benzoyl peroxide, 1.96 ± 1.33 for Chlorhexidine acetate, 3.11 ± 0.48 for organic iodine, and 4.69 ± 0.23 for triclosan-sulfur-salicylic acid. Each S intermedins recovery value from the 4 treated sites was significantly (P < 0.05) lower than that from the nontreated S intermedins challenge-exposed control site. Bacteria recovery values were also significantly (P < 0.05) different among the 4 shampoo-treated sites.

We concluded that all shampoos had significant (P < 0.05) prophylactic activity against S intermedins over 5 hours. The shampoo containing benzoyl peroxide was determined to have the greatest efficacy among the products tested.

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in American Journal of Veterinary Research

Summary

The susceptibility of 50 clinical Escherichia coli isolates to various antibacterials, including cefoxitin and cefotetan was ascertained, and the minimal inhibitory concentration (mic) of cefoxitin and cefotetan for each of these isolates was determined. The pharmacokinetics of cefoxitin and cefotetan after a single iv or sc injection (30 mg/kg of body weight) were determined in 4 dogs. Of the 50 E coliisolates, 98% were susceptible in vitro to cefotetan, 90% were susceptible to cefoxitin, and 88% were susceptible to gentamicin. The mic that would inhibit the growth of 90% of the E coliisolates (mic 90) was 0.25 µg/ml for cefotetan and 4 µg/ml for cefoxitin. Plasma cefotetan concentrations remained above mic 90 for (mean ± SD) 8.2 ± 1.72 8.2 ± 1.72 hours and 13.52 ± 0.28 hours after iv and sc administration, respectively. Plasma cefoxitin concentrations remained above mic 90 for (mean ± SD) 5.37 ± 1.18 hours and 7.95 ± 0.71 hours after iv and sc administration, respectively. We concluded that cefotetan was superior to cefoxitin·was superior to cefoxitin in activity against E coli in vitro. We recommend that cefotetan be given at a dosage of 30 mg/kg, iv, every 8 hours, Or sc, every 12 hours.

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in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

Seventy-three aerobic bacterial isolates were cultured from 64 eyes of 63 horses with infectious keratitis. Forty-two (58%) of the organisms isolated initially were gram-positive (g+, 10 genera) and 31 (42%) were gram-negative (g-, 5 genera). After local antimicrobial treatment, repeat cultures from samples obtained from 15 eyes of hospitalized horses yielded 21 secondary bacterial isolates. Staphylococci spp and Streptococci spp were the most common g(+) isolates and accounted for 79% of g(+) organisms isolated initially. Antibiograms revealed ticarcillin to be the most efficacious antibiotic tested on g(+) organisms, with 28 of 30 (93%) being susceptible. Of commercially available topical ophthalmic antibiotics tested on g(+) organisms, erythromycin was the most efficacious, with 32 of 35 (91%) isolates being susceptible. Pseudomonas spp, Escherichia coli, and Acinetobacter spp accounted for 68% of g(-) organisms isolated initially. Gentamicin, tobramycin, polymyxin B, and neomycin were highly effective in vitro against initial g(-) isolates. Chloramphenicol was ineffective against g(+) and g(-) organisms isolated initially. A significantly (P < 0.05) higher frequency of g(-) organisms was noticed on repeat cultures after intensive topical antimicrobial treatments as compared to organisms isolated at initial examination. Pseudomonas organisms isolated from second cultures were resistant to gentamicin, but susceptible to ciprofloxacin. Overall, secondary g(-) isolates were more susceptible to ciprofloxacin, neomycin, tobramycin, or amikacin than to gentamicin. Fungi were isolated in 24 of 63 (38%) horses in the study. Twenty-five filamentous fungi and 2 yeasts were identified from 24 eyes. Aspergillus spp was the predominant fungi; it was detected in 17 of 22 (77%) eyes in which filamentous fungi were identified.

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in Journal of the American Veterinary Medical Association

Summary

An antibiotic selected for surgical antimicrobial prophylaxis must be present in the surgical site throughout the operation in concentration sufficient to prevent growth of contaminating pathogens. The antimicrobial spectrum, minimal toxicity, and low cost of cefazolin make this first-generation cephalosporin a logical choice for antimicrobial prophylaxis in small animal surgical procedures in which the normal microbiologic flora of skin and gastrointestinal tract are the most likely pathogens. Pharmacokinetic variables of cefazolin were determined in serum and surgical wounds in dogs. Drug concentration in interstitial fluid of muscle biopsy specimens taken at random from wound surfaces and in postoperative wound fluid samples were determined. Effective surgical wound concentration of cefazolin was defined as 4 μg/ml, a concentration that inhibited the growth in vitro of 100% of staphylococcal and 80% of Escherichia coli clinical isolates. After iv and sc administrations, cefazolin equilibrated rapidly between serum and the surgical wound, and concentrations in the 2 sites decreased in parallel. With a bolus dose of 20 mg/kg of body weight given iv at the beginning of surgery and repeated by sc administration at 6 hours, cefazolin concentration in the surgical wound remained > 4 μg/ml for longer than 12 hours.

Free access
in American Journal of Veterinary Research

SUMMARY

Once-daily administration of aminoglycosides may be a safe and effective therapeutic regimen, on the basis of the microbiologic and pharmacokinetic characteristics of these antibiotics. This study was designed to determine serum and tissue concentrations following IV administration of gentamicin, at dosages of 6.6 mg/kg of body weight, every 24 hours, and 2.2 mg/kg, every 8 hours, for 10 days in adult horses. Nephrotoxicosis from these dosage regimens also was compared, and microbiologic effects, including postantibiotic effects, were determined with various concentrations of gentamicin against an equine clinical isolate of Pseudomonas aeruginosa. Treatment at the 6.6-mg/kg dosage resulted in maximal serum concentrations (77.93 ± 19.90 μg/ml, mean ± sem) and area under the concentration-vs-time curves (83.79 ± 14.97 μg.h/ml) that were significantly (P < 0.05) greater than those following treatment at the 2.2-mg/kg dosage (5.05 ± 0.50 μg/ml and 6.03 ± 0.66 μg.h/ml, respectively). Nephrotoxicosis was not induced with either dosage regimen, and postantibiotic effects were prolonged with a higher gentamicin concentration. This study provided evidence to support the use of once-daily gentamicin treatment in adult horses.

Free access
in American Journal of Veterinary Research