Bacteriophage Biocontrol Rescues Mice Bacteremic of Clinically Isolated Mastitis from Dairy Cows Associated with Methicillin-Resistant <i>Staphyloccocus aureus</i>

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most alarming pathogens affecting both humans and the global bovine industry. The current control measures in hospitals and on farms for MRSA have proven to be inadequate leaving a need for new rapid control methods to curb MRSA infections in situ. New control measures for bacterial infection are widely sought, with particular interest in the applications for bacteriophages (phages) as a biocontrol or therapeutic agent. The current study uses a wild highly lytic phage isolated from cow’s milk taken from three farms in Baghdad, Iraq. The resulting phage was able to rescue 100% of the mice from a median lethal dose (LD50) or (1 × 108 CFU mL-1 per mouse) for MRSA wild isolates achieved when the phage: bacteria ratio was 100:1. Even when treatment was delayed for 6 h post lethal infection, to the point where all mice were moribund, 80% of them were rescued by a single injection of this phage preparation. Based on the current results, a comprehensive study is needed to guide further research on the MRSA phage as a biocontrol for MRSA mastitis in dairy cows to replace or reduce the use of antibiotics in animal husbandry.

Risk of methicillin-resistant Staphylococcus aureus prosthetic joint infection in elective total hip and knee arthroplasty following eradication therapy

Re-screening following methicillin-resistant Staphylococcus aureus(MRSA) decolonization will be helpful to minimize the development of prosthetic joint infection among MRSA colonizers.

Ophthalmic methicillin-resistant <i>Staphylococcus aureus</i>infections: Sensitivity and resistance profiles of 65 isolates in central California

Purpose: To capture the sensitivity and resistance trends of ophthalmic Methicillin-resistant Staphylococcus aureus (MRSA) in a heterogenous demographic. Methods: Between 1/1/2004-12/31/2011, ophthalmic MRSA infections were searched in the electronic medical record system ofCommunityRegionalMedicalCenterinFresno,California. We reviewed whether the infection was community-acquired or hospital-acquired, culture site, and sensitivity/resistance profiles. Results: The ophthalmic MRSA isolates tested for vancomycin, sulfamethoxazole-trimethoprim, and gentamycin were 100% sensitive to these to these antibiotics. Tetracycline and rifampin had the next highest sensitivity to resistance ratio, followed by clindamycin. More cases were community-acquired than hospital acquired. Almost half of the hospital-acquired cases were in newborns. Most hospital acquired infections were post-ophthalmic surgery. Conclusion: There is an increasing trend of community- acquired ophthalmic MRSA infection with eyelid involvement being the most common manifestation. Hospital-acquired cases are common in newborns and post-ophthalmic surgery. Have a high index of suspicion for MRSA infection with suspected “insect bites”. Vancomycin, sulfamethoxazole-trimethoprim, gentamycin, tetracycline, and rifampin are good choices to treat ophthalmic MRSA infection. There may be emerging resistance to clindamycin, at least in theCentral Californiaregion. If MRSA infection is suspected, erythromycin and fluoroquinolones should be avoided.

Antibacterial Activity of Exogenous Glutathione and Its Synergism on Antibiotics in Methicillin-Associated Multidrug Resistant Clinical Isolates of Staphylococcus aureus

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most problematic human pathogens. Antibiotic treatment of MRSA often associated with resistance to multiple classes of antibiotics is extremely challenging and urgently demands action to treat MRSA. Glutathione (GSH) is a biogenic thiol-compound that maintains an optimal intracellular redox-potential required for various normal cellular processes. Antibacterial activity of exogenous GSH has been reported in some bacterial pathogens but is largely unknown in MRSA. Aim: This study aimed to understand antibacterial activity of GSH, its role in antibiotic susceptibility, and a potential antibacterial mechanism in clinical isolates of S. aureus. Materials and Methods: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), checkerboard, time-killing, and bacterial killing assays were performed for 14 clinical isolates of S. aureus including 10 MRSA and two type strains (ATCC 700699 and 35556). Results: MIC and MBC levels for the clinical and type strains were 15 - 20 mM and 25 - 40 mM of GSH, respectively. Subinhibitory concentrations of GSH synergistically enhanced susceptibility of all tested-antibiotics, resulting in sensitizing all-tested S. aureus. Bacterial-killing produced by GSH-mediated acidity was significantly higher than that by hydrochloric acid-mediated acidity. Conclusion: Overall results concluded that GSH exhibited antibacterial activity on S. aureus regardless of antibiotic susceptibility and synergistically enhanced antibiotic susceptibility. Additionally, GSH-mediated acidity was one of the antibacterial mechanisms. These findings suggest that GSH may be a potential antimicrobial agent or adjuvant for the conventional anti-MRSA regimens.

A New Epidemiological Tool for <i>Staphylococcus aureus</i>Surveillance

Epidemiological surveillance for microbes is currently based on either agar culture followed by identification, or genetic amplification. Both techniques are highly skilled-labor intensive, costly, and must be done in central laboratories. The Defined Substrate Utilization&reg;(DSU&reg;) format provides an epidemiological series of specific screening formulations that obviate these limitations. All reagents are present in optimized stable powder form in a test tube—add water, inoculate, and incubate. A specific color change provides a sensitive and specific detection of the target microbe. Two DSU&reg;methods for Staphylococcus aureus (S. aureus) are presented: aureusAlert&reg;for all S. aureus and EPI-M&reg;for methicillin-resistant S. aureus (MRSA). Both aureusAlert&reg;and EPI-M&reg;had a detection level of 20 colony forming units (CFU) in 18 hours. aureusAlert&reg;and conventional methods agreed 93.6% and EPI-M&reg;and conventional methods agreed 94.1%. DSU&reg;and conventional methods showed the same specificity.

A report on intraspinal abscess due to community-acquired methicillin-resistant Staphylococcus aureus infection

To the Editor: The incidence of community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection and reports of CA-MRSA infection have been increasing yearly. But community-acquired intraspinal methicillin-resistant Staphylococcus aureus (MRSA) infection has never been reported. We describe a case of intraspinal abscess due to CA-MRSA infection.

Clonal and drug resistance dynamics of methicillin-resistant Staphylococcus aureus in pediatric populations in China

Importance:Regional clonal replacements of methicillin-resistant Staphylococcus aureus (MRSA) are common.It is necessary to understand the clonal and drug resistance changes in specific areas.Objective:To evaluate the clonal and drug resistance dynamics of MRSA in Chinese children from 2010 to 2017.Methods:MRSA was isolated from patients in Beijing Children's Hospital from 2010 to 2013 and from 2016 to 2017.The molecular characteristics and antibiotic resistance were determined,Results:In total,211 MRSA isolates were collected,and 104 isolates were classified as community-associated MRSA (CA-MRSA).ST59-SCCmec Ⅳ was the most prevalent type in both CA-MRSA (65.4%) and healthcare-associated-MRSA (HA-MRSA) (46.7%).ST239-SCCmec Ⅲ accounted for 21.5% of all HA-MRSA,which were not detected in 2016,and only three isolates were detected in 2017.The pvl gene carrying rate of CA-MRSA was significantly higher than that of HA-MRSA (42.3% vs.29.0%,P =0.0456).Among CA-MRSA,resistance rate to all tested antibiotics excluding chloramphenicol remained stable over the periods of 2010-2013 and 2016-2017.HA-MRSA displayed an overall trend of decreased resistance to oxacillin,gentamicin,tetracycline,ciprofloxacin,and rifampin,and increased resistance to chloramphenicol,consistent with the difference of antibiotic resistance patterns between ST59-SCCmec Ⅳ and ST239-SCCmec Ⅲ isolates.Vancomycin minimal inhibitory concentration (MIC) creep was found in the study period in all MRSA and ST59-SCCmec Ⅳ isolates.Interpretation:ST59-SCCmec Ⅳ has spread to hospitals and replaced the traditional ST239-SCCmec Ⅲ clone,accompanied by changes in drug resistance.Furthermore,vancomycin MIC creep indicated that the rational use of antibiotics should be seriously considered.

New cyslabdans B and C, potentiators of imipenem activity against methicillin-resistant Staphylococcus aureus produced by Streptomyces sp. K04-0144

From a further purification study,two new congeners designated cyslabdans B(1)and C(2)were isolated along with previously reported cyslabdan(cyslabdan A(3)in this study)from the culture broth of Streptomyces sp.K04-0144.The structure was elucidated by various spectroscopy including NMR,revealing that 1 and 2 was 18-hydroxy and 10-methoxy cyslabdan,respectively.Compounds 1 and 2 were found to potentiate imipenem activity against methicillinresistant Staphylococcus aureus by 123 fold and 533 fold,respectively.Comparison with the activity of compound 3 indicated that the introduction of a hydrophilic group at the dimethyl moiety of the decalin ring was unfavorable for its activity.

Enhanced antibacterial activity of silica nanorattles with ZnO combination nanoparticles against methicillin-resistant Staphylococcus aureus

Silica nanorattles(SNs) with zinc oxide(ZnO) combination nanoparticles are reported to inhibit methicillin-resistant Staphylococcus aureus(MRSA) for the first time. SNs loaded with ZnO nanoparticles,which can produce free radicals, can cause severe damage to bacteria. ZnO nanoparticles not only provide free radicals in the combined nanostructures, which can inhibit the growth of bacteria, but also form nanorough surfaces with an irregular distribution of spikes on the SNs, which can enhance their adhesion to bacteria. Nanorough silica shell surfaces maintain the high activity and stability of small-sized ZnO nanoparticles and gather ZnO nanoparticles together to enhance production, which improves the efficiency of free radicals against the cytomembranes of bacterial cells. The enhanced adhesion of ZnO@SN nanoparticles to MRSA cells shortens the effective touching distance between free radicals and MRSA, which also improves antibacterial activity. As we expected, the ZnO@SN nanoparticles exhibit a better antibacterial effect than free ZnO nanoparticles against MRSA in vitro and in vivo. We also demonstrate that SNs loaded with ZnO nanoparticles can accelerate wound healing in MRSA skin inflammation models. This method of multilevel functionalization will be potentially applicable to the antibacterial field.

Methicillin-resistant Staphylococcus aureus in acute otitis externa

Objective:Otologic methicillin-resistant Staphylococcus aureus(MRSA)infection has historically been rare,but given the rise in community-acquired MRSA carriage and infection at other body sites,prevalence rates may be changing.The goal of this study was to determine the prevalence of MRSA in recent otologic cultures from patients with acute otitis externa(AOE).Study design:Retrospective review of an institutional microbiologic database.Methods:A retrospective analysis was performedon serial culture isolates taken fromthe ear at a quaternary care hospital from January 2014 to April 2016.The causative pathogen and antibiotic sensitivity was determined by culture isolation and end point mean inhibitory concentration(MIC)testing.Medical records were reviewed to document patient characteristics,chronicity of infection,symptomatology,and previous treatments.Results:Over the study period,173 patients were diagnosed with AOE and underwent otologic cultures of the ear.Fifty-three(30.6%)of cultures grew S.aureus(SA).Of SA infections,15(28.3%)were identified as MRSA.MRSA patients were typically older than patients with methicillin-sensitive SA(MSSA)(mean age 46.7
17.9 vs 29
19.4,PZ0.003)and had more medical comorbidities(4 vs 1.7,PZ0.001).Compared to patients with MSSA,patients with MRSAwere significantly more likely to have had prior ototopical antibiotic exposure(37%vs 73%,PZ0.019).Conclusion:Contemporary ear culture isolates at quaternary care center show higher rates of MRSA compared to historical reports in the literature.Clinicians should consider ear cultures to identify MRSA AOE.Level of Evidence:IV.

Antibacterial activities of a novel Cu-bearing high-entropy alloy against multi-drug-resistant Acinetobacter baumannii and Staphylococcus aureus

Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus(MRSA)are two prevalent pathogens and have developed high resistant to most antibiotics.Therefore,it is a pressing need to develop a new method to inhibit the spread of drug-resistant bacteria.Copper containing high-entropy alloy(HEA,Al0.4CoCr-CuFeNi)is a new kind of alloy material,which shows extensive antibacterial activity and mechanical properties in our previous research.This study further develops another HEA(CoCrCuFeNi)and evaluates its resistance against gram-negative A.baumannii and Gram-positive MRSA.The antibacterial tests show that the antibacterial rate of the HEA toward both bacteria reached nearly 99%,far better than the traditional copper-bearing 304 stainless steel(304 Cu-SS).The biofilm observation shows that the HEA could not only kill the planktonic bacteria,but also effectively inhibit the formation of biofilm.These data demonstrate that CoCrCuFeNi HEA possesses effective antibacterial and antibiofilm activities,making it a potential candidate for using in hospital,food industry,and domestic kitchens.

Super Antibiotics, Part II. Hyperforin, Mass Spectroscopy (MS) and Gas Chromatography-Mass Spectrometry (GC-MS), Evidence of Permeability of the Blood-Testis Barrier (BTB) and the Blood-Brain Barrier (BBB) to Hyperforin

In the first article of this series, we presented some evidence of hyperforin as an antibiotic, antiprotozoal, antiviral, anticancer, and immunomodulatory substance. In the present article, evidence of the permeability of the blood-testis barrier (BTB) and blood-brain barrier (BBB) to hyperforin and its distribution in other organs of the domestic pig (Sus scrofa domesticus) are revealed. Seven-month-old male boars with a body mass of 100 kg were fed a diet containing hyperforin. Organs were surgically removed under anesthesia. Organs were suitable prepared and extracted, and then analyzed using gas chromatography-mass spectrometry with supersonic molecular beams (GC-MS with SMB). The presence of hyperforin was recorded in all organs and body fluids. Special attention was paid to the evaluation of the presence of hyperforin in the brain and testes of experimental animals. The presence of hyperforin in the brain and testes of experimental animals was established by GC-MS with SMB. The results are of interest because penicillin and numerous other antibiotics cannot pass through the BTB or BBB if healthy or non-inflamed, which limits their use in patients with meningitis and gonorrhea. The findings are also of interest in cases of penicillin- and multi-antibiotic-resistant bacterial infections.

In vitro and in vivo antibacterial activity of Pogostone

Background Our pervious antibacterial studies on several traditional Chinese medicines have found that Patchouli oil from Pogostemon cablin had significant antibacterial activity against methicillin-resistant Staphylococcus aureus （MRSA）,which has spread worldwide and infected innumerable people.In order to find the more active natural substances in Patchouli oil,one of the major components,Pogostone,was isolated and its antibacterial activity was evaluated in vitro and in vivo in this study.Methods In vitro test,Pogostone was screened for antimicrobial properties against 83 bacteria comprising 35 gram positive and 48 gram negative bacteria strains via the agar double dilution method.In vivo test,specific pathogen free （SPF） strain of both male and female white Kunming mice,weighing 18-22 g,were used to test the protective ability of Pogostone after being injected with the median lethal doses （MLDs） of the tested strains.Results In vitro test,Pogostone could inhibit both gram negative bacteria （0.098-1 600 μg/ml） and gram positive bacteria（0.098-800 μg/ml）.For Corynebacterium xerosis and some Chryseobacterium indologenes,the minimum inhibitory concentration （MIC） values of Pogostone were extremely low （＜0.098 μg/ml）.It was significant that Pogostone was also active against some drug-resistant bacteria like MRSA.Furthermore,Pogostone showed antibacterial activity in vivo against Escherichia coli （E.coli） and MRSA via intraperitoneal injection.Ninety percent of the mice infected with E.coil could be protected at the concentrations of 50 and 100 mg/kg,and 60％ of the mice at 25 mg/kg,while the rate of protection for the mice infected with MRSA was 60％ and 50％ at doses of 100 and 50 mg/kg,respectively.Conclusion Pogostone could be developed as a potential antibacterial agent for clinical therapy.