In vitro antimicrobial effect and in vivo preventive and therapeutic effects of partially purified lantibiotic lacticin NK34 against infection by Staphylococcus species isolated from bovine mastitis

Abstract

Lantibiotics are small (<5 kDa), polycyclic peptides produced by gram-positive bacteria; they are also known as gram-positive bacteriocins. The high antimicrobial activity of lacticins and the continuing appearance of antibiotic-resistant bacteria in recent years have resulted in a renewed interest in lantibiotics. A partially purified form of lacticin NK34 (a Lactococcus lactis product isolated from the Korean fermented fish jeotgal) was tested to determine its antimicrobial effects against Staphylococcus aureus (n=20) and coagulase-negative Staphylococcus (CNS, n=20) strains isolated from the raw milk of cows with subclinical bovine mastitis in the present study. The spot-on-lawn assay was used to identify the 2 strains from each group with the greatest lacticin NK34 susceptibility, and the minimal lethal dose (MLD) was measured in ICR (imprinting control region) mice. The preventive and therapeutic effects of lacticin NK34 on the mouse infection model were determined for the first time. Lacticin NK34 demonstrated antimicrobial effects in 14 of 20 (70%) S. aureus indicator strains and in 18 of 20 (90%) CNS strains. Staphylococcus aureus 69 and S. simulans 55 demonstrated the greatest susceptibility to lacticin NK34 in the spot-on-lawn assay. The S. aureus 69 MLD was measured at 1.53 x 10(9) cfu/mouse, whereas the S. simulans 55 MLD was 3.59 x 10(9) cfu/mouse. Mice infected experimentally with S. aureus 69 MLD or S. simulans 55 MLD were treated with lacticin NK34. Treated mice demonstrated an 80% survival rate (48 of 60 mice) compared with a survival rate of 7.5% (3 of 40 mice) in control mice treated with distilled water. These data suggest that lacticin NK34 might be useful in the control of bovine mastitis and systemic bacterial infection.

Screening a Phage Display Library for Two Novel OmpU-Binding Peptides with Adhesion Antagonistic Activity against Vibrio mimicus

“…The survival experiment was performed in accordance with the practices reported in recent studies on antibacterial efficacy of peptides in vivo , protective efficacy of vaccine and bacterial virulence [12–14]. Death was used as an endpoint in these studies (with no indication of use of humane euthanasia).…”

Efficacy of lacticin NK34 against bovine intramammary infections caused by Staphylococcus aureus and Streptococcus agalactiae

“…The preparation of the Lactococcus lactis-produced bacteriocin NK34 was carried out according to the method of Kim et al [12]. Bacterial examination of milk samples was conducted with standard laboratory techniques [21].…”

“…Technical and scientific developments have not been able to eradicate the disease from the world. One third of all cows are believed to have mastitis in at least one of the breasts; however, most farmers are unaware of the prevalence of this disease [12,25]. The economic loss due to bovine mastitis has been estimated to be about $1.8 billion per year in the United States [26] due to reduced milk production, degraded milk quality, increased replacement costs, discarded milk, drug costs, veterinary fees, and labor costs for the farmers [6,10].…”

“…In addition, NK34 has been applied in vivo to a murine infection model with various strains of Staphylococcus spp. [12]. Although it is well known that over 150 different contagious or environmental microorganisms are associated with bovine mastitis [15], we aimed to evaluate the antimicrobial effect of NK34 against the two major bacteria species responsible for contagious bovine mastitis: S. aureus and S. agalactiae [3,8] both in vitro and in vivo bovine model systems.…”

Estudo da ação de microrganismos probióticos sobre patógenos causadores de mastite em bovinos de leite

“…al, 2008;RABOT, et al, 2010;ROLFE, 2000;SADRZADEH-YEGANEH, et al, 2010) ANAS et al, 2008;CRISPIE et al, 2008;FROLA et al, 2012;KIM et al, 2010;SOLEIMANI et al, 2010;ESPECHE et al, 2012 células bacterianas/célula epitelial .…”