Staphylococcal Strains Research Articles

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Kyiv Surgical Hospital (Ukraine)

Objective — to determine the prevalence of methicillin-resistant strains of Staphylococcus aureus, isolated from patients different departments in Kyiv Surgical Hospital.
 Materials and methods. Between June 2015 and December 2015, a total of 128 S. aureus isolates were collected from the pus samples of the patients with SSI in a surgical hospital in Kyiv, Ukraine. The identification and antimicrobial susceptibility of the cultures were determined, using automated microbiology analyzer VITEK 2 Compact (bioMerieux, France). Susceptibility to antibiotics was determined using VITEK 2 AST-P580 card (bioMerieux, France), which included 20 antibiotics (benzylpenicillin, oxacyllin, cefoxitin, gentamycin, tobramycin, levofloxacin, moxifloxacin, erythromycin, clindamycin, linezolid, teicoplanin, vancomycin, tetracycline, tigecycline, fosfomicin, nitrofurantoin, fusidic acid, mupirocin, rifampicin, and trimethoprim/ sulphamethoxazole) and a cefoxitin test, designed for detection of staphylococci resistance to methicillin. Interpretative criteria were those suggested by the Clinical and Laboratory Standards Institute (CLSI).
 Results and discussion. Based on antimicrobial susceptibility analysis, the most active antibiotics found in the study were linezolid, tigecycline, and mupirocin, showing growth inhibition of 100 % strains tested. Susceptibility to the other antimicrobials was also on a high level: 99 % of strains were found susceptible to nitrofurantoin and trimethoprim/sulphamethoxazole, 98 % — to fusidic acid, 97 % — to moxifloxacin, 96 % — to teicoplanin, 95 % — to vancomycin and fosfomicin, 93 % — to gentamycin, and 92 % — to tobramycin. Susceptibility to levofloxacin (89 %), tetracycline (88 %), rifampin (87 %), erythromycin (84 %), and clindamycin (79 %) was observed to be some lower. Research of MRSA prevalence in Kyiv Surgical Hospital (Ukraine) shown, that 11 % of staphylococci strains, isolated from patients having nosocomial infections (SSI), had multiple resistance to antibiotics. Resistance S. aureus to oxacyllin came up to 19 %. Further, 35.7 % of MRSA strains were resistant only to the group of beta-lactamic antibiotics, while the rest — also to the other classes of antibiotics.
 Conclusions. MRSA in surgical hospital, being a subject of the research is considered to be a serious therapeutic and epidemiologic problem. Total prevalence of MRSA in hospital was evaluated as 19 %, varying in every surgical department studied. Antibiotics revealed the most effective for treatment of MRSA infections were linezolid, mupirocin, tigecycline, vancomycine, teicoplanin, moxifloxacin, nitrofurantoin, fusidic acid, and trimethoprim/sulphamethoxazole. Taking into account the constant changes and significant differences of the S. aureus resistance levels observed in various regions, the constant monitoring of antibiotic resistance to antimicrobials in every in-patient medical institution is required and on the base of the local obtained results to elaborate the hospital record sheets. Antibiotics application tactics should be determined in accordance with the local data of resistance to them in each surgical inpatient institution. The system of epidemiologic surveillance over microbial resistance should be established on the local, regional, and national levels.

Expression of Staphylococcal Enterotoxins under Stress Encountered during Food Production and Preservation.

Staphylococcal food poisoning (SFP) is the most prevalent cause of food-borne intoxications worldwide. Consumption of enterotoxins preformed in food causes violent vomiting and can be fatal in children and the elderly. While being repressed by competing bacteria in most matrices, Staphylococcus aureus benefits from crucial competitive advantages in foods with high osmolarity or low pH. During recent years, the long-standing belief in the feasibility of assessing SFP risk based on colony-forming units of S. aureus present in food products has been disproven. Instead, researchers and food business operators are acutely aware of the imminent threat arising from unforeseeable enterotoxin production under stress conditions. This paradigm shift led to a variety of new publications enabling an improved understanding of enterotoxin expression under stress conditions encountered in food. The wealth of data provided by these studies is extremely diverse, as it is based on different methodological approaches, staphylococcal strains, stressors, and enterotoxins. Therefore, in this review, we aggregated and critically evaluated the complex findings of these studies, to provide readers with a current overview of the state of research in the field.

Serratiopeptidase reduces the invasion of osteoblasts by Staphylococcus aureus.

Finding new strategies to counteract periprosthetic infection and implant failure is a main target in orthopedics. Staphylococcus aureus, the leading etiologic agent of orthopedic implant infections, is able to enter and kill osteoblasts, to stimulate pro-inflammatory chemokine secretion, to recruit osteoclasts, and to cause inflammatory osteolysis. Moreover, by entering eukaryotic cells, staphylococci hide from the host immune defenses and shelter from the extracellular antibiotics. Thus, infection persists, inflammation thrives, and a highly destructive osteomyelitis occurs around the implant. The ability of serratiopeptidase (SPEP), a metalloprotease by Serratia marcescens, to control S. aureus invasion of osteoblastic MG-63 cells and pro-inflammatory chemokine MCP-1 secretion was evaluated. Human osteoblast cells were infected with staphylococcal strains in the presence and in the absence of SPEP. Cell proliferation and cell viability were also evaluated. The release of pro-inflammatory chemokine MCP-1 was evaluated after the exposure of the osteoblast cells to staphylococcal strains. The significance of the differences in the results of each test and the relative control values was determined with Student’s t-test. SPEP impairs their invasiveness into osteoblasts, without affecting the viability and proliferation of bone cells, and tones down their production of MCP-1. We recognize SPEP as a potential tool against S. aureus bone infection and destruction.

Microbial air contamination on the premises of the sewage treatment plant in Bydgoszcz (Poland) and antibiotic resistance of Staphylococcus spp.

AbstractThe study was aimed at evaluating microbial contamination on the premises of the sewage treatment plant by determining the concentrations of selected groups of airborne microorganisms. Another objective was to determine the antibiotic sensitivity patterns of isolated strains of staphylococci. The research was conducted in a seasonal cycle, by the impaction method using Merck MAS-100 air sampler. Samples were collected at six sites, each representing a different stage of sewage treatment. The susceptibility of isolated staphylococci was assessed with the disc-diffusion method, following the recommendations of the EUCAST. The results indicate that the microbial population in the air of the investigated area was dominated by mold fungi, whose highest average concentration was recorded at site IV located near the final clarifier (7672 CFU•m-3). Heterotrophic bacteria and mannitol-positive staphylococci were the most numerous at locations where sewage undergoes primary treatment. In each subseuqent stage the number of microorganisms emitted into the air from the sewage was lower. Antibiograms show that more than 50% of Staphylococcus spp. exhibited resistance to penicillin and 20% to rifampicin. In addition, 90% of the analyzed strains were sensitive to other antibiotics. The fungal community included the following genera: Cladosporium, Fusarium, Alternaria, Penicillium, Aspergillus, Aureobasidium, and Acremonium.The highest air contamination with all studied groups of microorganisms was recorded at the locations where mechanical sewage treatment was performed. During the subsequent stages lower numbers of heterotrophic bacteria were emitted into the air. The air in the investigated sewage treatment plant did not contain multidrug-resistant staphylococci.

Coagulase-Negative Staphylococcal Strain Prevents Staphylococcus aureus Colonization and Skin Infection by Blocking Quorum Sensing

Coagulase-negative staphylococci (CoNS) and Staphylococcus aureus are part of the natural flora of humans and other mammals. We found that spentmedia from the CoNS species Staphylococcus caprae can inhibit agr-mediated quorum sensing by allclasses of S.aureus. A biochemical assessmentofthe inhibitory activity suggested that the S. caprae autoinducing peptide (AIP) was responsible,and mass spectrometric analysis identified the S.caprae AIP as an eight-residue peptide (YSTCSYYF). Using a murine model of intradermal MRSA infection, the therapeutic efficacy of synthetic S.caprae AIP was evident by a dramatic reduction in both dermonecrotic injury and cutaneous bacterial burden relative to controls. Competition experiments between S.caprae and MRSA demonstrated a significant reduction in MRSA burden using murine models of both skin colonization and intradermal infection. Our findings indicate that important interactions occur between commensals that can impact disease outcomes and potentially shape the composition of the natural flora.

Anti-tubercular and probiotic properties of coagulase-negative staphylococci isolated from Koozh, a traditional fermented food of South India

In the last few years, the demand for the tremendous therapeutic applications of indigenous probiotic bacteria from diversified fermented food products has surged. In view of this, the present study was documented to evaluate the anti-tubercular and probiotic properties of coagulase-negative staphylococci (CNS) indigenous to Koozh, a traditional fermented food product of South India. A total of 18 isolates were purified from Koozh, and tested for anti-tubercular activity against Mycobacterium tuberculosis H37Rv using luciferase reporter phage (LRP) assay. Among them, six isolates revealed higher percentage (>90%) of relative light unit (RLU) reduction. These six isolates were further evaluated for their in vitro probiotic attributes using standard protocols. All six staphylococci strains disclosed good probiotic properties. Moreover, Staphylococcus hominis strain MANF2 showed high cell survival percentage (92.2%) at pH 2.0 as well as towards simulated gastric juice (88.51%). Furthermore, strain MANF2 was found to be resistant to bile salt after 24h of incubation with maximal viability of 5.71±0.02 log cfu/mL, and depicted the deconjugation of bile salt as well. All the isolates exhibited strong auto-aggregation capacity (44.4±1.2-68.1±1.5%), and hydrophobicity against toluene (55.0±1.2-72.0±1.1%). Additionally, strain MANF2 was observed to be highly resistant to phenol (6.27±0.01 log cfu/mL) and lysozyme (81.1±1.6% viability). Most importantly, all six isolates depicted good hypocholesterolemic effect, slight β-galactosidase activity, and moderate proteolytic property. The strains were sensitive to all the tested conventional antibiotics, except Nalidixic acid. In addition to this, all staphylococci strains demonstrated significant DPPH (2,2-Diphenyl-1-picrylhydrazyl) scavenging, hydrogen peroxide tolerance, and hydroxyl radical scavenging activity in a dose dependent manner, thereby exhibiting the potent antioxidative properties of isolates. The negative results obtained from haemolytic, DNase, and gelatinase tests revealed the non-pathogenicity and safety aspect of these strains. In a nutshell, the present investigation divulges the persuasive anti-tubercular and probiotic properties of staphylococci, particularly strain MANF2, and recommended the further exploitation of Koozh associated CNS in pharmaceutics.

Replication of Staphylococcal Resistance Plasmids.

The currently widespread and increasing prevalence of resistant bacterial pathogens is a significant medical problem. In clinical strains of staphylococci, the genetic determinants that confer resistance to antimicrobial agents are often located on mobile elements, such as plasmids. Many of these resistance plasmids are capable of horizontal transmission to other bacteria in their surroundings, allowing extraordinarily rapid adaptation of bacterial populations. Once the resistance plasmids have been spread, they are often perpetually maintained in the new host, even in the absence of selective pressure. Plasmid persistence is accomplished by plasmid-encoded genetic systems that ensure efficient replication and segregational stability during cell division. Staphylococcal plasmids utilize proteins of evolutionarily diverse families to initiate replication from the plasmid origin of replication. Several distinctive plasmid copy number control mechanisms have been studied in detail and these appear conserved within plasmid classes. The initiators utilize various strategies and serve a multifunctional role in (i) recognition and processing of the cognate replication origin to an initiation active form and (ii) recruitment of host-encoded replication proteins that facilitate replisome assembly. Understanding the detailed molecular mechanisms that underpin plasmid replication may lead to novel approaches that could be used to reverse or slow the development of resistance.

Monitoring of antimicrobial susceptibility of udder pathogens recovered from cases of clinical mastitis in dairy cows across Europe: VetPath results

VetPath is an ongoing pan-European antimicrobial susceptibility monitoring programme collecting pathogens from diseased cattle, pigs and poultry not recently treated with antibiotics. Non-duplicate milk samples were collected from cows with acute clinical mastitis in nine countries and 934 isolates were obtained during 2009–2012 for subsequent antimicrobial susceptibility testing in a central laboratory. CLSI broth microdilution methodology was used, and where available, MICs were interpreted using CLSI approved veterinary-specific (ceftiofur) otherwise human clinical breakpoints.Among Escherichia coli (n=207) and Klebsiella spp., (n=87), resistance was moderate to tetracycline and high to cephapirin (E. coli only) whereas resistance to other β-lactam antibiotics was very low (ceftiofur) to low (amoxicillin/clavulanic acid, cephalexin, cephalonium). The MIC90 of enrofloxacin and marbofloxacin was 0.03 and 0.06μg/mL respectively (E. coli) with 0.5% strains displaying higher MICs. Staphylococcus aureus (n=192) and coagulase-negative staphylococci (CNS; n=165) strains were susceptible to most antibiotics tested except to penicillin (25.0 and 29.1% resistance), respectively. Three S. aureus and seven CNS strains were oxacillin-resistant and harboured mecA. Streptococcus uberis strains (n=188) were susceptible to the β-lactam antibiotics although 35.6% were penicillin intermediately susceptible, and 20.2% were resistant to erythromycin, 36.7% to tetracycline. For Streptococcus dysgalactiae (n=95) the latter figures were 13.7 and 56.8%, respectively.For most antibiotics, the percentage resistance among E. coli, S. aureus and S. uberis was comparable to that of the VetPath 2002–2006 survey. This current, expanded VetPath study shows that mastitis pathogens were susceptible to most antibiotics with exceptions of staphylococci tested against penicillin and streptococci against erythromycin or tetracycline. This work highlights the high need to set additional clinical breakpoints for antibiotics frequently used to treat mastitis.

The arginase pathway of L-arginine metabolism of peripheral blood lymphocytes in patients with acne vulgaris

The mechanisms of development of the inflammatory process of the pilosebaceous apparatus in patients with acnе vulgaris are not fully understood, and variations in bacterial colonization are one of the key elements of the inflammatory process. Under the pathological conditions caused by pus-forming cocci which induce the production of proinflammatory cytokines, there is an increase in arginase expression. The capacity for film formation in selected strains was determined by the cultural properties (increased viscosity of the colony biomass) and by differential interference contrast microscopy using a dark field condenser and fluorescence microscopy. Arginase activity (μmole urea/min•mg of protein) was determined spectrophotometrically at 520 nm on saponin-perimabilized lymphocytes of peripheral blood by the rate of urea formation. The cultures of film-forming and planktonic forms of Staphylococcus epidermidis and Staphylococcus aureus were isolated from purulent pustules of 44 patients, aged 18–30. 63.6% of clinical strains of film-forming staphylococci were isolated, out of which 15 strains (53.6%) were S. aureus and 13 strains (46.4%) S. epidermidias. It was found that the arginase activity in patients (film-forming S. aureus) was significantly higher than in practically healthy donors (control) and was equal to 0.262 ± 0.006 and 0.279 ± 0.005 (planktonic form of S. aureus) versus 0.087 ± 0.009 μmole urea / min∙mg of protein in the control. The arginase activity in patients (film-forming S. epidermidis) was significantly higher than in practically healthy donors and was equal to 0.281 ± 0.009 and 0.297 ± 0.006 (planktonic form of S. epidermidis) versus 0.087 ± 0.009 μmol urea / min∙mg of protein in the control. After the auto-vaccine therapy and the administration of the probiotic Lacidofil (Institut Rosell Inc., Canada), enzyme activity decreased significantly in both experiments, however it had not attained control levels. The enzyme activity decreased through the administration of a vaccine, which in turn has an immunomodulating and immunostimulating effect. In addition, comparing the data of the arginase activity after treatment in patients with S. epidermidis, there was a slight decrease in the enzyme activity. This result is probably due to the formed tolerance of the immune system to commensal microorganisms. It was found that all patients had a moderate dysbiosis, which was accompanied by a deficiency of the main normal symbionts of the intestine. After treatment, all patients experienced significant improvementst in the microbiocenosis of the intestine in the direction of normalization of parameters and improvement of the skin condition. Increase in arginase activity in patients with acne vulgaris indicates the competition of this enzyme with NO-synthases for the substrate L-arginine and the alteration of physiological reactions in the organism caused by staphylococci which induce the phagocytic response and the cytokines production of the humoral system.

Characteristics of Microbiocenosis of Wounds in Patients with Skin and Soft Tissue Infections on the Background of Type II Diabetes Mellitus

Relevance. Assessment of microbiocenosis of wounds in patients with infections of the skin and soft tissues is an integral part of the complex of diagnostic measures carried out for patients of this nosological group, which allows predicting the severity of the course of the purulent inflammatory process and monitoring the effectiveness of the selected method of systemic and local treatment.
 Objective: To assess the microbiocenosis of wounds in patients with infections of the skin and soft tissues against the background of type II diabetes mellitus and the effectiveness of using a local, directed flow of the ozone-oxygen gas mixture.
 Materials and methods. A qualitative and quantitative assessment was made, an analysis of the antibiotic resistance of the microbial composition of wound biopsies in 90 patients in three clinical groups. The first group consisted of patients with background type II diabetes mellitus who underwent local wound sanation with an ozone-oxygen gas mixture as the local treatment, the second and third groups consisted of patients receiving basal therapy as a topical treatment. However, in the second group, type II diabetes mellitus was registered in patients, while in the third group there were patients without it.
 Results and discussion. Based on the results of the microbiocenosis assessment, it was found that in patients with background type II diabetes mellitus, in addition to representatives of staphylo-, strepto-, enterococci and enterobacteria, nonfermentative Gram-negative bacteria were significantly more often from the biopsy specimens of the wounds, which were represented by acinotobacteria. Significantly higher in the first two groups methicillin-resistant strains of staphylococci were verified. Along with the difference in the qualitative composition of the pathogens in the study groups at the time of admission, pathogens of the purulent-inflammatory process in patients with background diabetes mellitus type II showed a high primary antibiotic resistance to the main classes of antimicrobial agents.
 Also, in the patients of the first group, a significantly lower incidence of secondary surgical interventions resulted from the persistence and superinfection of wounds from the data of the dynamic microbiological evaluation of the causative agents.
 Key words: skin and soft tissue infections, type II diabetes, purulent wounds, ozone, local treatment of wounds.

Resistance of nosocomial strains to antibacterial drugs and its link to biofilm formation

The problem of nosocomial infections is considered in connection with more frequent formation and wide distribution in clinical practice of new strains of hospital bacteria that have a cross-resistence to antibacterial drugs. The nosocomial agents were isolated from wounds and identified as Staphylococcus aureus and Pseudomonas aeruginosa. 72.0% of S. aureus strains and 61.5% of P. aeruginosa clinical isolates had the capability of forming biofilms. The sensitivity to antibiotics of all isolated strains was investigated with tne agar diffusion test. This method showed that all strains of S. aureus with the capability to form biofilms had resistence to erythromycin, gentamycin, ciprofloxacin and levofloxacin. The had the greatest sensitivity to klindamycin (90.3%), vancomycin (80.6%) and gatifloxacin (80.6% cultures). The strains of S. aureus with the capability to form biofilms were more resistent to antibiotics than strains of S. aureus without such properties. Only cefotaxim suppressed the growth of 75.0% of strains of staphylococci. All isolated strains of S. aureus without the capability to form biofilms were sensitive to doxycyclin, gentamycin, ciprofloxacin, levofloxacin and klindamycin. All clinical isolates of P. aeruginosa with capability to form biofilms had resistence to ampicillin, gentamycin, imipenem, cefotaxime and ceftriaxone. They were most sensitive (75.0%) to piperacillin and cefoperazone/sulbactam. The strains of P. aeruginosa without the capability to form biofilms kept the resistence to gentamycin, imipenem and ceftriaxone. They showed the greatest sensitivity (75.0%) to ciprofloxacin (80.0% isolates) and also to amikacin, ampicillin, meropenem, norfloxacin and cefotaxime (60.0% cultures). We investigated the minimum inhibitory concentrations of gentamycin and ciprofloxacin, which appeared higher for P. aeruginosa than for S. aureus. The most effective disinfectant against all isolated nosocomial agents without the capacity for biofilm formation was “Desactin” in a concentration 0.1% or 0.2%. For strains of staphylococci with this capability, the efficiency of “Desactin” went down by 9.7%. The best biocide effect against the strains of P. aeruginosa with the capability of forming biofilms was shown by 0.1% solution of “Neochlorine tabs”, which suppressed the growth of 75.0% of tested cultures. As a result, we detected a direct relationship between resistance to antibiotics and disinfectants and the capacities for biofilm formation among the nosocomial agents S. aureus and P. aeruginosa.

Adhesive properties of film-forming strains of staphylococci, isolated from different compartments of the human gastrointestinal tract

Dysbiotic disorders, realized as changes in the composition of microbiota of different biotopes, are among the most difficult conditions to cure. This is due primarily to the fact that opportunistic microorganisms that actually mediate the development of such states are characterized by an increased colonization potential, which at the first stage of penetration into a biotope is realized as adhesion to the cell surface. When a microorganism successfully realises this stage it enters into a competitive relationship with the autochthonous flora and begins to inhibit its development. Such strategy becomes especially successful if the colonist has the ability to form a biofilm. It is known that the initial stage of biofilm formation is adhesion onto the surface, therefore, the study of adhesive properties of clinical strains opens the way for understanding the initial processes of development of dysbiosis and allows for the development of preventive measures. The aim of our research was to investigate the differences in the manifestation of adhesive properties of film-forming strains of staphylococci isolated from different compartments of the human gastrointestinal tract. We established that the frequency of detection of film-forming strains of staphylococci in different compartments of the gastrointestinal tract in the norm or during the development of lesions was for Staphylococcus aureus from 23.8% to 79.4%, and for S. epidermidis from 15.4% to 100%, which indicates the significant role of these microorganisms in the development of complications at the specified biotope. It was determined that the maximal manifestation of adhesive properties was typical for biofilm-forming strains of S. epidermidis and S. aureus isolated during intestinal dysbiosis. The average values of the adhesion index were 6.00 ± 1.41 and 5.88 ± 2.22 and the index of adhesion of microorganisms was 6.61 ± 1.46 and 6.64 ± 2.48 respectively. The lowest value of these indices for film-forming strains was determined for strains of staphylococci isolated from the gastrointestinal tracts of patients suffering from food poisoning – 2.60 ± 1.14 and 2.86 ± 1.23 respectively. The obtained data suggest that the ability for biofilm-formation and a high level of adhesion indexes indicate with a high probability that a strain will cause long-lasting lesions, such as dysbiosis. The determination of these markers at the diagnostic stage will allow a broader study of the biological properties of the strain, which may be the basis for the development of an individual, optimal therapeutic scheme that conforms with the tasks of personalized medicine.

Rapid identification of staphylococci by Raman spectroscopy

Clinical treatment of the infections caused by various staphylococcal species differ depending on the actual cause of infection. Therefore, it is necessary to develop a fast and reliable method for identification of staphylococci. Raman spectroscopy is an optical method used in multiple scientific fields. Recent studies showed that the method has a potential for use in microbiological research, too. Our work here shows a possibility to identify staphylococci by Raman spectroscopy. We present a method that enables almost 100% successful identification of 16 of the clinically most important staphylococcal species directly from bacterial colonies grown on a Mueller-Hinton agar plate. We obtained characteristic Raman spectra of 277 staphylococcal strains belonging to 16 species from a 24-hour culture of each strain grown on the Mueller-Hinton agar plate using the Raman instrument. The results show that it is possible to distinguish among the tested species using Raman spectroscopy and therefore it has a great potential for use in routine clinical diagnostics.

Anti-staphylococcal properties of four plant extracts against sensitive and multi-resistant bacterial strains isolated from cattle and rabbits

The aim of this study is to investigate the biopotency of methanolic extracts of Vitex mollis, Psidium guajava, Dalbergia retusa, and Crescential alata leaves against various staphylococcal strains isolated from cattle and rabbits. Methicillin-resistant S. aureus strains were isolated from cattle, while other strains were isolated from rabbits using standard methodology. The total phytochemical phenolic and saponins contents were obtained being the main groups of the antinutritional factors. The antimicrobial activity of the extracts against the standard culture of S. aureus (control) and S. aureus isolated from cattle and rabbits were investigated comparatively relative to that of oxacillin. It was found that both the control S. aureus and the isolated S. aureus are susceptible to all the four plant extracts, and sensitive to oxacillin. Of all the S. aureus including the control, MRSA2 is the most susceptible to all the extracts at 1000 μg/mL, except that of V. mollis where it is the least susceptible. Among all the plant extracts, P. guajava is the most active against MRSA2 and SOSA2. Therefore, the isolates from cattle (MRSA1 and MRSA2) are more susceptible to all the plant extracts than the isolates from rabbits. Among all the rabbit isolates, CoNS3 is the least susceptible to the extracts. Since all the plant extracts exhibit remarkable inhibitory activities against all the S. aureus strains, they are promising towards the production of therapeutic drugs.

Anti-staphylococcal properties of Eichhornia crassipes, Pistacia vera, and Ziziphus amole leaf extracts: Isolates from cattle and rabbits

The desideratum aim of the present context was to assess the biopotency of methanolic extracts of Eichhornia crassipes (E. crassipes), Pistacia vera (P. vera), and Ziziphus amole (Z. amole) leaves against various staphylococcal strains, and to quantify the phenolics as well as saponin content in them. The antibacterial activity of various concentrations (62.5–1000 μg/mL) of plant extracts was tested against control clinical strains (Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, and S. aureus ATCC 43300), methicillin-resistant S. aureus (MRSA1 and MRSA2), oxacillin sensitive S. aureus (SOSA1 and SOSA2), and coagulase-negative Staphylococcus epidermidis (CoNS1, CoNS2, and CoNS3) using disc diffusion assay. Leaf extracts of the three plants exhibited pronounced growth inhibitory characteristics against staphylococci in a dose dependent manner. E. crassipes extract depicted the highest relative percentage inhibition values against control clinical strains (68.6 ± 0.5%), while P. vera (68.6 ± 0.3%) and Z. amole (74.79 ± 0.3%) extracts showed pronounced relative inhibition values against staphylococcal strains isolated from cattle. Total phenols and saponin content of leaf extracts were investigated by standard in vitro methods. The methanolic extracts of these plants were found to comprise substantial content of phenolics and saponin at varying levels. The highest value of phenolics was estimated in P. vera extract (60.0 ± 1.3 mg gallic acid/g extract), followed by Z. amole (33.6 ± 1.4 mg gallic acid/g extract), and E. crassipes (23.0 ± 1.3 mg gallic acid/g extract). Saponin content for P. vera, Z. amole, and E. crassipes extracts were estimated as 41.0 ± 1.3, 35.8 ± 1.3, and 25.0 ± 1.2 mg diosgenin/g extract, respectively. The outcome of this study suggested the exploitation of methanolic extract of P. vera, Z. amole, and E. crassipes leaves for their possible application in ethnomedicine, particularly as drugs preparation against staphylococcal infections. In conclusion, the study indicates the biopotency of these plants against pathogenic MRSA present in cattle, and SOSA as well as CoNS bacteria present in rabbits, which could be a serious issue for livestock.

Biofilm-Forming Clinical Staphylococcus Isolates Harbor Horizontal Transfer and Antibiotic Resistance Genes.

Infections caused by staphylococci represent a medical concern, especially when related to biofilms located in implanted medical devices, such as prostheses and catheters. Unfortunately, their frequent resistance to high doses of antibiotics makes the treatment of these infections a difficult task. Moreover, biofilms represent a hot spot for horizontal gene transfer (HGT) by bacterial conjugation. In this work, 25 biofilm-forming clinical staphylococcal isolates were studied. We found that Staphylococcus epidermidis isolates showed a higher biofilm-forming capacity than Staphylococcus aureus isolates. Additionally, horizontal transfer and relaxase genes of two common staphylococcal plasmids, pSK41 and pT181, were detected in all isolates. In terms of antibiotic resistance genes, aac6-aph2a, ermC, and tetK genes, which confer resistance to gentamicin, erythromycin, and tetracycline, respectively, were the most prevalent. The horizontal transfer and antibiotic resistance genes harbored on these staphylococcal clinical strains isolated from biofilms located in implanted medical devices points to the potential risk of the development and dissemination of multiresistant bacteria.

Antimicrobial activity and preliminary mode of action of PlnEF expressed in Escherichia coli against Staphylococci

Strains belonging to the genus of Staphylococci, such as Staphylococcus aureus are common pathologic bacteria which may cause nosocomial cross infection and food contamination. Plantaricin EF (PlnEF), a two-peptide nonlantibiotic bacteriocin produced by Lactobacillus plantarum strains, shows great inhibitory effects against Gram-positive Staphylococci strains. To overproduce this two-peptide bacteriocin, plnE and plnF genes were cloned into pET32a (+) vector and heterologously expressed in Escherichia coli by fusion with His6-tag in this study. The purified fusion proteins were cleaved by enterokinase, then PlnE and PlnF peptides without extra amino acids were obtained by a two-step purification method, ultrafiltration centrifuge (10 kDa) followed by a reverse-phase HPLC. Purity of PlnE and PlnF, determined by analytical HPLC, is ∼98%, and their molecular mass confirmed by ESI-MS was 3545.14 Da and 3703.1 Da, respectively. It was found that the two peptides had significant antimicrobial activities against Staphylococcus citreus and Staphylococcus aureus strains and they functioned synergistically. PlnEF exerted its bactericidal activity against Staphylococci strains by permeabilizing the cell membrane, causing influx and efflux of various molecules across the transmembrane barrier, eventually leading to cell death.

Emergence of rifampin-resistant staphylococci after rifaximin administration in cirrhotic patients.

ObjectivesRifaximin, a poorly absorbed antibiotics, has gut-specific therapeutic effects. Although frequently prescribed to manipulate intestinal luminal bacterial population in various diseases, the possible induction of antibacterial cross-resistance to a target pathogen is a major concern in long-term rifaximin administration. We aimed to evaluate whether rifampin-resistant staphylococci could evolve after rifaximin treatment in cirrhotic patients.MethodA total of 25 cirrhotic patients who were administered rifaximin for the prevention of hepatic encephalopathy were enrolled. Swabs from both hands and the perianal skin were acquired on day 0 (before rifaximin treatment), period 1 (1–7 weeks after treatment), and period 2 (8–16 weeks after treatment) the staphylococcal strain identification and rifampin-resistance testing.ResultsA total of 198 staphylococcal isolates from 15 species were identified. Staphylococcus epidermidis was isolated most frequently, and Staphylococcus haemolyticus was the most common resistant species both from hands and perianal skin. Eleven patients (44.0%) developed rifampin-resistant staphylococcal isolates in period 1. Among these patients, only six (54.5%) were found to have rifampin-resistant isolates in period 2, with no significant infectious events. Rifampin-resistant staphylococcal isolates were more frequently found in perianal skin than from the hands. No patients acquired a newly resistant strain in period 2.ConclusionsAbout one-half of cirrhotic patients in this study developed rifampin-resistant staphylococcal isolates after rifaximin treatment. Although the resistant strains were no longer detected in about half of the patients in the short-term, the long-term influence of this drug treatment should be determined.

Synergistic effects of ethanol medicinal plant extracts with erythromycin against skin strains of staphylococci with inducible phenotype of MLS-resistance

Synergistic effects of ethanol medicinal plant extracts with erythromycin against skin strains of staphylococci with inducible phenotype of MLS-resistance

Methicillin-resistant coagulase-negative staphylococci in healthy dogs

The objective of this study was to evaluate the prevalence of coagulase-negative staphylococci in healthy dogs and to determine whether methicillin-resistant staphylococci expressed the mecA gene. Nasal and rectal swab samples were taken from 50 clinically healthy dogs. The prevalence of coagulase-negative staphylococci was evaluated according to phenotypic properties. The agar diffusion method was applied to evaluate antimicrobial resistance and the prevalence of methicillin resistance was determined using PCR analysing the mecA gene. A total of 59 coagulase-negative staphylococcus strains were isolated from the nostrils and rectums of 37 (74%) clinically healthy dogs. The prevalence of coagulase-negative staphylococci in female dogs was significantly higher compared with male dogs (P < 0.05). The results of antimicrobial susceptibility testing showed that 6.7% of the strains were resistant to oxacillin, 23.7% were resistant to penicillin, 22% to ampicillin and 16.9% to erythromycin. The mecA PCR revealed one oxacillin-sensitive and four oxacillin-resistant coagulase-negative staphylococci strains to be mecA carriers. Staphylococcus sciuri (60%) and Staphylococcus warneri (20%) were the most prevalent species among methicillin-resistant coagulase negative staphylococci. High antimicrobial resistance rates for these bacteria were observed against penicillin (100%), ampicillin (100%), oxacillin (80%), erythromycin (80%) and gentamicin (60%). All strains were susceptible to vancomycin and enrofloxacin. It is assumed that methicillin-resistance genes evolved in coagulase-negative staphylococcus and were then horizontally transferred among staphylococci.