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Abstract
Mastitis is a complicated disease that is caused by interaction of the agent, animal, and environment. It is a major animal and public health problem with global economic implications. The primary zoonotic pathogen is Staphylococcus aureus…
Abstract
Mastitis is a complicated disease that is caused by interaction of the agent, animal, and environment. It is a major animal and public health problem with global economic implications. The primary zoonotic pathogen is Staphylococcus aureus, necessitating the implementation of control strategies in dairy farms.
The purpose of this study was to determine the efficacy of synthesized Silver nanoparticles in treating experimentally induced mastitis with S. aureus in lactating local breed goats, as well as their potential alternative usage for mastitis treatment. Between January and August 2021, the study was divided into four parts to accomplish the objectives at the Faculty of Veterinary Medicine and Science/University of Kufa in Iraq.
The first part was determining the prevalence of Staphylococcus mastitis and S. aureus isolates in 185 lactating goats in the Al-Najaf district. A total of 338 milk samples were collected and subjected to physical examination, the California mastitis test (CMT), a Somatic cell count (SCC), and bacteriological examination which used as standard techniques to isolate and identify bacteria. The VITEK2 system was used to validate the diagnosis, and isolates were evaluated for antibiotic sensitivity. The prevalence of infection with S. aureus mastitis was reported to be 43.75 % in clinical cases and 29.87 % in subclinical cases. Antibacterial susceptibility testing revealed that 22 isolates of S. aureus were 100 % susceptible to Gentamicin.
The second part investigated the biosynthesis and characterization of Silver nanoparticles (AgNPs) by bacteria using Bacillus clausii, as well as their antibacterial and antibiofilm activities. AgNPs were biosynthesized by introducing silver nitrate (AgNO3) to Bacillus clausii cell-free supernatant at a concentration of (1 mM). The biosynthesis of AgNPs was initially suggested by the reaction mixture changing color from yellow to reddish brown. UV-VIS spectrophotometer, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and atomic force microscope (AFM) were used to characterize biosynthesized nanoparticles.
The size, shape, and distribution of nanoparticles were examined using SEM. The nanoparticles were found to be spherical and homogeneous in shape and ranged in size from 25 to 45 nm. EDS analysis was used to determine the presence of elemental silver. XRD measurements revealed that the average size of biogenic AgNPs was 50 nm. The three-dimensional structure of AgNPs was revealed by AFM, and the average diameter was 47.18 nm. According to these approaches for AgNPs was demonstrated against S. aureus isolated from clinical mastitis in goats. The highest inhibition zone of AgNPs against S. aureus was (14 mm) at a concentration of (80 μg/ml); moreover, antibiofilm activity against the same bacteria was 17.3 ± 2.7 μg/ml. The minimum inhibitory concentration (MIC) of biosynthesized AgNPs against S. aureus was 16 ± 2.4 μg /ml, whereas the MBCs was 32 ± 3.4 μg /ml.
The third part of the study was inducing mastitis using isolated S. aureus. Thirty-five apparently healthy Iraqi lactating local breed goats were employed, ranging in age from 2 to 5 years, in early to mid-lactation, and weighing 40.5 ± 0.5 kg. Five lactating goats were left uninfected as a control negative (group I), and thirty lactating goats were intramammary inoculated with 1.5 × 108 CFU/ml of S. aureus isolated from caprine mastitis milk. At 48 hrs post inoculation, the animals were randomly separated into six equal groups. Clinical examination (body temperature, heart rate, and respiration rate), chemical investigation of milk (CMT and SCC), macroscopic inspection of the udder, and bacteriological examination of milk samples were obtained 24 hrs, 48 hrs, and 72 hrs post infection. Animals frequently exhibit clinical indications prior to infection. However, as compared to the negative control group, there was a substantial increase in body temperature, respiration, and heart rate, indicating udder inflammation, a change in milk consistency, and the isolation of S. aureus from milk in infected groups.
The fourth part of the study evaluated the effect of biologically synthesized AgNPs on mastitis treatment. The positive control group (II) was left untreated, while the group (III) received an intramammary infusion of a single dose of 5 ml/halve AgNPs 17 mg after 2 hrs post infection, group (IV) intramammary infusion of 5 ml/halve AgNPs 17 mg after 72 hrs post infection daily for 3 consecutive days, group (V) intramammary infusion of 5 ml/halve AgNPs 8.5 mg in combination with gentamicin 50 mg after 72 hrs post infection daily for 3 consecutive days, group (VI) intramammary infusion of a single dose of 5 ml/halve AgNPs 17 mg after 72 hrs post infection, and group (VII) intramammary infusion of 5 ml/halve gentamicin 100 mg after 72 hrs post infection daily for 3 consecutive days.
Clinical cure was determined by collecting milk samples from does at 3, 6-, 9-, 12-, 14-,21- and 28-days following treatment for SCC and bacterial isolation. Additional analyses examined rectal body temperature, heart and respiration rates, inflammatory changes in mammary secretion, and gland tissues. Treatment cure rates for group III, IV, and V infections caused by S. auerus were 100%. According to the current data, severe bacteria were isolated from the mammary glands of animals in group VI and a positive control group, whereas light bacteria were obtained from animals in group VII that were treated withgentamicin alone. However, no bacteria were isolated following intramammary treatment with AgNPs alone or in combination with gentamicin. The study indicated that AgNPs can be used as an alternative therapy for induced S. aureus mastitis in local breed goats, showing that AgNPs have potential medicinal applications in the veterinary field due to their efficacy, low cost, and convenience of handling. It is recommended due to AgNPs' antimicrobial properties and their suitability for intramammary infusion.
To the best of our knowledge, there are scanty studies on just the effect of AgNPs on S. aureus, that lead to biofilm-related infections associated with mastitis in local breed goats in Iraq. Although the effects of AgNPs have been described in vitro, no study has examined their potential application in goats to eliminate mastitis-causing bacteria. The findings suggest novel therapeutic approaches for mastitis in dairy animals. Thus, the most significant conclusion of this study is that AgNPs may be employed as a bactericide to effectively treat mastitis in veterinary medicine. Synergistic, combination therapy with other conventional antibiotics was urgently needed to reduce nanoparticle concentrations, overcome microbial resistance to conventional antibiotics, and result in more effective antibacterial action for the treatment of animal diseases.characterization of silver nanoparticles, Bacillus clausii was capable of biosynthesizing AgNPs. Antibacterial efficacy of biosynthesized
