Inhibition of urease activity in the urinary tract pathogens Staphylococcus saprophyticus and Proteus mirabilis by dimethylsulfoxide (DMSO)

Intramammary preparation of enrofloxacin hydrochloride-dihydrate for bovine mastitis (biofilm-forming Staphylococcus aureus)

BACKGROUND

Chronic bovine mastitis is linked to biofilm-producing Staphylococcus aureus (bp-Sa) or Staphylococcus coagulase-negative (bp-Scn).

OBJECTIVES

Bp-Sa and bp-Scn were treated with intramammary preparations of either enrofloxacin HCl·2H2O-dimethyl-sulfoxide-chitosan (enro-C/DMSO/chitosan) or enro-C alone. Their potential to inhibit and degrade biofilm formation in vitro was also assessed.

METHODS

Milk samples were obtained from the affected quarters in a herd. Phenotypical and genotypical identifications as biofilm-producing Staphylococcus species were carried out. Enro-C/DMSO/chitosan and enro-C alone were assessed to determine their in vitro efficacy in interfering with biofilm formation and their bactericidal effects. A prolonged eight-day treatment with a twice-daily intramammary insertion of 10 mL of enro-C/DMSO/chitosan or enro-C alone was set to evaluate the clinical and bacteriological cures on day 10 in 15 cows per group and the biofilm-inhibiting ability.

RESULTS

Fifty-seven percent of the isolates were identified as Staphylococcus spp., of which 50% were bp-Sa, 46% bp-Scn, and 4% Staphylococcus pseudintermedius. One hundred percent of the S. aureus isolated and 77% of Staphylococcus coagulase-negative were biofilm producers. In both groups, the icaA and icaD biofilm-producing genes were identified. The experimental preparation could inhibit biofilm formation, degrade mature biofilms, and have well-defined microbicidal effects on planktonic and biofilm bacteria. The respective clinical and bacteriological cure rates were 100% and 80% for enro-C/DMSO/chitosan and 41.7% and 25% for enro-C alone.

CONCLUSIONS

Enro-C/DMSO/chitosan eliminates bp-Sa and bp-Scn from cases of chronic bovine mastitis.

An Update on Arginase Inhibitors and Inhibitory Assays

Arginase, which converts arginine into ornithine and urea, is a promising therapeutic target. Arginase is involved in cardiovascular diseases, parasitic infections and, through a critical role in immunity, in some cancers. There is a need to develop effective arginase inhibitors and therefore efforts to identify and optimize new inhibitors are increasing. Several methods of evaluating arginase activity are available, but few directly measure the product. Radiometric assays need to separate urea and dying reactions require acidic conditions and sometimes heating. Hence, there are a variety of different approaches available, and each approach has its own limits and benefits. In this review, we provide an update on arginase inhibitors, followed by a discussion on available arginase assays and alternative methods, with a focus on the intrinsic biases and parameters that are likely to impact results.

Lactoferrin-Derived Peptides as a Control Strategy against Skinborne Staphylococcal Biofilms

Coagulase-negative staphylococci (CoNS) widely colonize the human skin and play an active role in host defense. However, these bacteria may cause malodours and increase infection incidence rate in immune-compromised patients and individuals with catheters and implants. CoNS spreading is favored by biofilm formation that also promotes the release of virulence factors and drug resistance. Biofilm control or eradication by antimicrobial peptides (AMPs) represents an attractive strategy which is worth investigating. In this work, bovine lactoferrin (BLF) hydrolysate (HLF) was in vitro evaluated for its antimicrobial and antibiofilm activities against skin-related coagulase negative and positive staphylococci. Despite a minimal inhibitory concentration (MIC) recorded for HLF ranging from 10 to more than 20 mg/mL, a minimal biofilm inhibitory concentration (MIBC) equal to 2.5 mg/mL was found for most target strains. Conversely, MIBC values referred to the individual peptides, LFcinB or LFmpin (herein purified and identified) were significantly lower. Finally, the application of 2.5 mg/mL HLF solution by dipping and spraying on biofilm-attached glass surfaces also caused a high biofilm eradication rate depending on the incubation time, thus attracting interest for future applications in cosmetic formulation for skin care.