Antimicrobial, Antibiofilm Activities and Synergic Effect of Triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene Isolated from Combretum leprosum Leaves Against Staphylococcus Strains.

Antimicrobial resistance is a natural phenomenon and is becoming a huge global public health problem, since some microorganisms not respond to the treatment of several classes of antibiotics. The objective of the present study was to evaluate the antibacterial, antibiofilm, and synergistic effect of triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene (CLF1) against Staphylococcus aureus and Staphylococcus epidermidis strains. Bacterial susceptibility to CLF1 was evaluated by minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay. In addition, the effect combined with antibiotics (ampicillin and tetracycline) was verified by the checkerboard method. The biofilms susceptibility was assessed by enumeration of colony-forming units (CFUs) and quantification of total biomass by crystal violet staining. The compound showed bacteriostatic and bactericidal activity against all Staphylococcal strains tested. The synergistic effect with ampicillin was observed only for S. epidermidis strains. Moreover, CLF1 significantly inhibited the biofilm formation and disrupted preformed biofilm of the all strains. Scanning electron microscopy (SEM) images showed changes in the cell morphology and structure of S. aureus ATCC 700698 biofilms (a methicillin-resistant S. aureus strain). Molecular docking simulations showed that CLF1 has a more favorable interaction energy than the antibiotic ampicillin on penicillin-binding protein (PBP) 2a of MRSA, coupled in different regions of the protein. Based on the results obtained, CLF1 proved to be a promising antimicrobial compound against Staphylococcus biofilms.

Critical role of epigenetic modification in the pathogenesis of atopic dermatitis.

Atopic dermatitis is a chronic inflammatory skin disease characterised by recurrent eczema-like lesions and severe pruritus, along with drying and decrustation of skin. Current research relates the pathogenesis of atopic dermatitis mainly to genetic susceptibility, abnormal skin barrier function, immune disorders, Staphylococcus aureus colonisation, microbiological dysfunction and vitamin D insufficiency. Epigenetic modifications are distinct genetic phenotypes resulting from environment-driven changes in chromosome functions in the absence of nuclear DNA sequence variation. Classic epigenetic events include DNA methylation, histone protein modifications and non-coding RNA regulation. Increasing evidence has indicated that epigenetic events are involved in the pathogenesis of atopic dermatitis by their effects on multiple signalling pathways which in turn influence the above factors. This review primarily analyses the function of epigenetic regulation in the pathogenesis of atopic dermatitis. In addition, it tries to make recommendations for personalised epigenetic treatment strategies for atopic dermatitis in the future.

Phytochemical prospection and evaluation of antimicrobial, antioxidant and antibiofilm activities of extracts and essential oil from leaves of Myrsine umbellata Mart. (Primulaceae).

The species Myrsine umbellata is a native plant of Brazil, whose barks are traditionally used in herbal medicine to treat liver disorders and combat leprosy. Therefore, the aim of the study was to identify the phytochemical prospection of ethanolic (EE) and acetonic (EA) extracts by colorimetric tests and by gas chromatography coupled to mass spectrometry (GC-MS) of the essential oil (EO) of M. umbellata leaves; evaluate the antimicrobial activity in front of standard ATCC strains by the broth microdilution technique; the antioxidant potential by DPPH reduction method and antibiofilm action by crystal violet assay and cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) based on optical density. Phytochemical prospection of EE and EA detected the presence of free steroids, alkaloids, flavonoids (flavones, flavononoids, flavonols and xanthons) and tannins in both extracts (EE and EA) and saponins only in EE. In EO, the majority compounds identified were elixene, caryophyllene (E), spatulenol, d-Cadinene and aromadendrene. EA showed antimicrobial activity with MIC and MBC/MFC values ranging from 3.12 to 100 mg.mL-1, highlighting its efficiency on the Gram-positive strain S. epidermidis. EE showed antimicrobial potential in the range of 3.12 to 200 mg.mL-1, and the Gram-negative E. coli strain was the most susceptible. However, OE showed bacteriostatic potential against S. Typhimurium, S. Abaetetuba, P. aeruginosa, and S. epidermidis strains. The ability to sequester free radicals was evident in EA extract with antioxidant activity of 89.55% and in EE with 63.05%. The antibiofilm potential was observed in EE extract which eradicated the mature biofilm biomass of all tested bacteria with high activity (50% to 84.28%) and EO also showed antibiofilm effect on mature biofilm of UEL enteroaggregative E. coli, S. aureus and S. Enteritidis strains with biomass reduction percentage of 63.74%, 68.04% and 86.19%, respectively. These results indicate the potential of M. umbellata extracts and as a source of plant bioactivity for the development of new alternative strategies for the control of planktonic or biofilm-resistant microorganisms.

Self-assembled zein organogels as in situ forming implant drug delivery system and 3D printing ink.

Recently, biomedical applications of organogels have been increasing; however, there is a demand for bio-based polymers. Here, we report self-assembled zein organogels in N-methyl pyrrolidone (NMP), Dimethyl sulfoxide (DMSO), and glycerol formal (GF). The gel formation was driven by the solvent's polarity and the hydrogen bonding component of Hansen Solubility Parameters was important in promoting gelation. Gels exhibited shear-thinning and thixotropic properties. Furthermore, water-induced self-assembly of zein allows mechanically robust in situ implant formation by solvent exchange. Ciprofloxacin was incorporated as a model drug and sustained release depending upon the solvent exchange rate was observed. In situ implants in agarose gel retained antibacterial efficacy against S. aureus for more than 14 days. Zein-based organogels were further applied as 3D printing ink and it was found that zein gel in DMSO had superior printability than gels prepared in NMP and GF. Using three solvents to prepare organogels can enable the encapsulation of various drugs and facilitate the preparation of composite gels with other biocompatible polymers. These organogel systems can further be used for developing 3D printed drug delivery systems or scaffolds for tissue engineering.

Systemic infections associated with tattoos or permanent makeup: A systematic review.

INTRODUCTION: The aim of this article is to summarize published information on systemic infective complications of tattoos to gain an update of the current picture. METHODS: A literature search was performed in PubMed database (2009-2019), and compared with a search without year restriction. Eligibility criteria were studies on systemic tattoo-related infections, including case reports, case series, outbreak investigations, reviews, and systematic reviews. RESULTS: We identified 17 manuscripts with systemic infections between 2009 and 2019, with one reported fatality. In contrast to the historical records, no reports of systemic tuberculosis, syphilis or viral (hepatitis or HIV) infections were reported within the study period. A few sporadic cases or Mycobacterium leprae (India) or regional lymphadenopathy associated with skin lesions in non-tuberculosis mycobacteria were identified. Persistent fever with rigour was common in bacterial bloodstream infections. One episode of staphylococcal toxic shock syndrome and several episodes of septic shock were reported, associated with cellulitis or necrotizing fasciitis within two weeks of the procedure, predominantly caused by pyogenic bacteria (S. aureus or streptococcus). Identification of lung or systemic embolisms in the absence of local symptoms, was indicative of (right or left) infective endocarditis. CONCLUSIONS: Bacterial bloodstream infections should be considered in subjects developing fever and rigour after tattoos, regardless of local symptoms. A shift in causative organisms has been documented, when comparing with historical reports. NTM are emerging organisms causing lymphadenopathy. Strict hygiene conditions are essential when performing a tattoo.

Lactic fermentation of cooked, comminuted mussel, Perna canaliculus.

The endogenous microflora of mussels, filter feeders, can include pathogens with resulting food safety concerns. The aim was to develop a cook-then-ferment technology to extend shelf life and safety of a ready-to-eat mussels. Only after cooking to destroy the mussel's endogenous microflora could an edible product be made as determined by pH decline after fermentation and the fate of common pathogens. Perna canaliculus was bought live at retail on many dates. Fermentation was with commercial lactic cultures incubated under vacuum at 30 °C for four days. Using one culture containing Pediococcus pentosaceus and Staphylococcus carnosus as a model, pH typically declined to 4.5 to 4.7, and common pathogens, Staphylococcus aureus, Salmonella and Vibrio parahaemolyticus were absent or reduced to acceptable levels. The fate of Listeria monocytogenes was studied with five cultures. These were variably effective at inhibition with one clear success, Chr Hansen's T-SC-150 containing a specific strain of Lactobacillus sakei, and flavour-generating Staphylococcus carnosus. This culture's efficacy was confirmed with sterile extracts of LAB challenging L. monocytogenes in vitro. This culture was also the most rapid fermenter by pH fall. Cook-then-ferment technology may be applied to other novel foods to minimise a disruptive endogenous microflora.

Prediction of rifampicin resistance beyond the RRDR using structure-based machine learning approaches.

Rifampicin resistance is a major therapeutic challenge, particularly in tuberculosis, leprosy, P. aeruginosa and S. aureus infections, where it develops via missense mutations in gene rpoB. Previously we have highlighted that these mutations reduce protein affinities within the RNA polymerase complex, subsequently reducing nucleic acid affinity. Here, we have used these insights to develop a computational rifampicin resistance predictor capable of identifying resistant mutations even outside the well-defined rifampicin resistance determining region (RRDR), using clinical M. tuberculosis sequencing information. Our tool successfully identified up to 90.9% of M. tuberculosis rpoB variants correctly, with sensitivity of 92.2%, specificity of 83.6% and MCC of 0.69, outperforming the current gold-standard GeneXpert-MTB/RIF. We show our model can be translated to other clinically relevant organisms: M. leprae, P. aeruginosa and S. aureus, despite weak sequence identity. Our method was implemented as an interactive tool, SUSPECT-RIF (StrUctural Susceptibility PrEdiCTion for RIFampicin), freely available at https://biosig.unimelb.edu.au/suspect_rif/ .

Antimicrobial activity of the lupane triterpene 3ß,6ß,16ß-trihydroxylup-20(29)-ene isolated from Combretum leprosum Mart.

Introduction. Combretum leprosum (Combretaceae) is commonly found in the Northeast Region of Brazil and is known for several bioactivities, including antimicrobial ones. Because of increasing bacterial antibiotic resistance, natural products from several plants have been studied as putative adjuvants to antibiotic activity, including products from C. leprosum. Aims. This study was carried out to investigate the structural properties, bactericidal activity and antibiotic modifying action of the lupane triterpene 3ß,6ß,16ß-trihydroxylup-20(29)-ene (CLF1) isolated from C. leprosum Mart. leaves.Methods. The CLF1 was evaluated by the Fourier transform infrared spectroscopy method and the antibacterial activity of this compound was assayed alone and in association with antibiotics by microdilution assay.Results. Spectroscopic studies confirmed the molecular structure of the CLF1 and permitted assignment of the main infrared bands of this natural product. Microbiological assays showed that this lupane triterpene possesses antibacterial action with clinical relevance against Staphylococcus aureus. The CLF1 triterpene increased antimicrobial activity against the multidrug-resistant Escherichia coli 06 strain when associated with the antibiotics gentamicin and amikacin. Synergistic effects were observed against the S. aureus 10 strain in the presence of the CLF1 triterpene with the antibiotic gentamicin.Conclusion. In conclusion, the CLF1 compound may be useful in the development of antibacterial drugs against the aforementioned bacteria.

Effectiveness of topical green tea against multidrug-resistant Staphylococcus aureus in cases of primary pyoderma: An open controlled trial.

BACKGROUND: Antimicrobial activity of green tea against Staphylococcus aureus both in vitro and in vivo has been reported recently. Studies on clinical efficacy and safety of green tea as antibacterial agent against S. aureus in human cases are rare. OBJECTIVES: To evaluate the clinical effectiveness and safety of topical green tea on primary pyoderma caused by S. aureus. We also attempted to determine the minimum inhibitory concentration of green tea against S. aureus and methicillin-resistant S. aureus. METHODS: Open label, prospective, placebo-controlled study included community-acquired primary pyoderma cases caused by S. aureus. Severity grading was done on a scale of 1-5. Green tea ointment 3% and placebo ointment were used. Cure was defined on the basis of negative culture and assessment of clinical improvement. Minimum inhibitory concentration was determined by agar dilution method. Data were analyzed using Statistical Package for Social Sciences (SPSS) software version 16. RESULTS: Of the 372 patients, 250 received green tea and 122 received placebo. Multidrug-resistant S. aureus was isolated in 89.1% in green tea group and 81.1% in placebo group, respectively. Methicillin-resistant S. aureus was isolated in 24 patients. Cure was seen in 86% in green tea group and 6.6% in placebo group which was statistically very significant. The number of days for comprehensive cure in green tea group was 9.2 ± 6.4 days. All patients with methicillin-resistant S. aureus infection in the green tea group were cured. Minimum inhibitory concentration of green tea against S. aureus was 0.0265 ± 0.008 µg/ml and against methicillin-resistant S. aureus was 0.0205 ± 0.003 µg/ml. LIMITATIONS OF THE STUDY: Comparative trial was not conducted in the same patient with different lesions; children less than seven years were not considered as the school authorities did not permit for younger children to be included in the study and true randomization and blinding of investigators were not done. CONCLUSIONS: Green tea has a significant antibacterial effect against multidrug-resistant S. aureus. Minimum inhibitory concentration of green tea is established and is promising in methicillin-resistant S. aureus infections.

Bactericidal and Fungicidal Activity in the Gas Phase of Sodium Dichloroisocyanurate (NaDCC).

Sodium dichloroisocyanurate (NaDCC) is usually employed as a disinfectant for the treatment of water, environmental surfaces and medical equipment principally for its effectiveness as a microbicide agent. In this study, we explore the possibility of a new use for NaDCC by investigating the microbicidal activity of chlorine, which derives from the hydrolysis of NaDCC mediated by air humidity, and by testing its effect on the neutralization of microbes present in domestic waste. NaDCC was inserted in a plastic garbage can where LB agar plates, with different dilutions of a known title of four different microorganisms (Escherichia coli, Staphylococcus aureus, Debaryomyces hansenii and Aspergillus brasiliensis), were weakly inserted. The molecular chlorine (Cl2) levels present in the garbage can were quantified using an iodometric titration. The gas emitted in the garbage can presented a strong microbicide effect, inhibiting the proliferation of all four microorganisms and for four consecutive weeks, thus showing that NaDCC hydrolysis, mediated by air humidity, is able to ensure the decontamination of restricted environments, avoiding the proliferation of both Gram-positive and Gram-negative bacteria as well as fungi.

Study of the antibacterial activity in the gas phase of a chemical formulation for household waste management.

UNLABELLED: The aim of this study was to formulate a product (microbicide mixture) that could slow down the bacterial proliferation during the storage of household waste. We used harmless and natural components, known for their antimicrobial properties, in the liquid phase at direct contact with the microbes. The antimicrobial activity of the microbicide mixture formulated was evaluated over a range of concentration in two types of tests, in the liquid and in the gas phase. Once the efficacy of antimicrobial agent in the liquid phase in direct contact with the microbe (Escherichia coli) was confirmed, we adopted a new approach to evaluate the effect of the vapour phase both on the microbes' growth and on its duration. Here, we show that the perfect combination that gives rise to an antimicrobial mixture useful to control microbial growth (Staphylococcus aureus, Escherichia coli, Debaryomyces hansenii or Penicillium citrinum) up to 4 weeks is the one between more volatile agents (2-propanol and limonene) and a less volatile agent (cinnamaldehyde). The pleasant smell as well as the synergic antibacterial and antifungal function of the natural components of this mixture makes it attractive in domestic waste management. SIGNIFICANCE AND IMPACT OF THE STUDY: The novelty of this work is two-fold: on the one hand, to test various antimicrobial components of different volatility in a single microbicide mixture, and on the other, to study antimicrobial activity in the gas phase, other than the liquid phase. While previous authors tested the components individually as antimicrobial agents in the liquid phase at direct contact with the microbes, we tested them altogether as a mixture both in the liquid and in gas phase. The aim of this study was to disinfect small environments, such as garbage containers, by favouring the diffusion of the vapour phase to avoid the growth of microbes. This study proposes a new approach in the management and storage of household waste by inhibiting bacterial proliferation in the garbage can.

Leprosy ulcers in a rural hospital of Ethiopia: pattern of aerobic bacterial isolates and drug sensitivities.

BACKGROUND: Plantar ulcers, which commonly occur in leprosy patients, tend to recur increasing physical disability. The aim of this study is to identify both the bacteriological profile of these ulcers and the antibiotic susceptibility of the isolated bacteria. MATERIALS AND METHODS: 68 leprosy patients with chronic ulcers attending the in-patient department of Gambo General Hospital, West Arsi, were included in this study. Proper sample collection, inoculation on culture media, and final identification using biochemical methods were undertaken. RESULTS: 66 patients (97.1%) had a positive culture. A total of 81 microorganisms were isolated. Multiple organisms (two or more) were isolated in 15 (22.7% out of positive culture) patients. The main isolation was Proteus spp (30.9%), followed by Escherichia coli (21.0%), Staphylococcus aureus (18.5%) and Pseudomonas aeruginosa (9.9%). In the total number of the isolated bacteria, the antibiotics with less resistance were gentamicin (18.5%), fosfomycin (22.2%) cefoxitin (24.7%), ceftriaxone (25.9%) ciprofloxacin (25.9%), and amoxicillin-clavulanic acid (28.49%). CONCLUSION: The bacteriological study of plantar ulcers of leprosy patients revealed Enterobacteriaceae and S. aureus as the main pathogens involved in such infections. The results of this study may guide empirical therapy in a rural area hospital where culture and susceptibility testing facilities are scarce.

Adhesion of the ulcerative pathogen Mycobacterium ulcerans to DACC-coated dressings.

OBJECTIVE: Mycobacterium ulcerans is the causative agent of Buruli ulcer disease, the third most common mycobacteriosis after tuberculosis and leprosy and an emerging public health threat in sub-Saharan Africa. The bacteria produce a diffusible cytotoxin called mycolactone, which triggers the formation of necrotic lesions in cutaneous and subcutaneous tissues. The principal aim of this study was to characterise the cell surface hydrophobicity of Mycobacterium ulcerans and determine if bacteria bind to dialkyl carbamoyl chloride (DACC)-coated dressings through hydrophobic interactions in vitro. Since mycolactone displays hydrophobic groups, a secondary aim was to compare mycolactone binding to hydrophobic and standard dressings. METHODS: We used hydrophobic interaction chromatography to evaluate the cell surface hydrophobicity of Mycobacterium ulcerans, compared to that of other microorganisms colonising wounds. The binding of Mycobacterium ulcerans bacteria to DACC-coated and control dressings was then assessed quantitatively by measurement of microbial adenosine triphosphate (ATP), while that of mycolactone was evaluated by fluorescence spectroscopy. RESULTS: Compared to Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, Mycobacterium ulcerans displayed the highest cell surface hydrophobicity, irrespective of the bacterial production of mycolactone. Mycobacterium ulcerans bacteria bound to DACC-coated dressings [corrected] better than untreated controls. Mycolactone did not bind stably to hydrophobic, nor standard dressings, in the conditions tested. CONCLUSION: Retention of Mycobacterium ulcerans and other wound pathogens to DACC-coated dressings may help reduce the bacterial load in Buruli ulcers and thereby improve healing. Dressings efficiently capturing mycolactone may bring an additional clinical benefit, by accelerating the elimination of the toxin during the course of antibiotic treatment.

Reduction of clofazimine by mycobacterial type 2 NADH:quinone oxidoreductase: a pathway for the generation of bactericidal levels of reactive oxygen species.

The mechanism of action of clofazimine (CFZ), an antimycobacterial drug with a long history, is not well understood. The present study describes a redox cycling pathway that involves the enzymatic reduction of CFZ by NDH-2, the primary respiratory chain NADH:quinone oxidoreductase of mycobacteria and nonenzymatic oxidation of reduced CFZ by O(2) yielding CFZ and reactive oxygen species (ROS). This pathway was demonstrated using isolated membranes and purified recombinant NDH-2. The reduction and oxidation of CFZ was measured spectrally, and the production of ROS was measured using a coupled assay system with Amplex Red. Supporting the ROS-based killing mechanism, bacteria grown in the presence of antioxidants are more resistant to CFZ. CFZ-mediated increase in NADH oxidation and ROS production were not observed in membranes from three different Gram-negative bacteria but was observed in Staphylococcus aureus and Saccharomyces cerevisiae, which is consistent with the known antimicrobial specificity of CFZ. A more soluble analog of CFZ, KS6, was synthesized and was shown to have the same activities as CFZ. These studies describe a pathway for a continuous and high rate of reactive oxygen species production in Mycobacterium smegmatis treated with CFZ and a CFZ analog as well as evidence that cell death produced by these agents are related to the production of these radical species.

Detecção de Staphylococcus aureus e Staphylococcus aureus resistentes à meticilina em profissionais da saúde lotados no Instituto Lauro de Souza Lima, Bauru-SP / Detection of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in health care workers packed the Instituto Lauro de Souza Lima, Bauru-SP

O Staphylococcus aureus (S. aureus) é um patógeno comumente isolado de amostras biológicas humanas. É encontrado com freqüência na pele e fossas nasais de indivíduos saudáveis, podendo provocar desde simples infecções ate graves enfermidades. Cerca de 40% da população adulta saudável é portadora nasal de S. aureus e esta taxa pode ser ainda maior em ambientes hospitalares, especialmente entre os pacientes internados e equipe médica. O surgimento da resistência à meticilina, uma penicilina sintética, pelo S. aureus e sua disseminação tornaram as medidas de controle epidemiológico ainda mais importantes no que diz respeito à prevenção de infecções hospitalares e, mais recentemente, comunitárias. Profissionais da área de saúde que são portadores nasais de S. aureus e Staphylococcus aureus resistentes a meticilina (MRSA) são considerados importantes fontes de disseminação do patógeno e estão intimamente envolvidos na epidemiologia dos mesmos. Investigação constante e adoção de medidas de controle na admissão dos pacientes em áreas de alta endemicidade para MRSA, tais com CTIs e centros de dermatologia, são consideradas estratégias efetivas em termos de custo-benefício contra as ionfecções hospitalares, bem como o estudo da prevalência de MRSA em profissionais de saúde que atuam nos referidos lugares. O objetivo do estudo foi verificar a colonização por S. aureus e MRSA nas fossas nasais de profissionais das equipes médicas de enfermagem e dos laborat´rios em um hospital de dermatologia de nível terciário - Instituto Lauro de Souza Lima - Bauru/SP...

Dermatitis cruris pustulosa et atrophicans.

Dermatitis cruris pustulosa et atrophicans (DCPA) is a distinctive type of chronic superficial folliculitis, primarily affecting the lower limbs. It is characterized by symmetrical follicular pustules of both legs, with cutaneous edema, resulting in alopecia, atrophy and scarring. It was first described by Clarke, from West Nigeria, in 1952 and well illustrated in his book "Skin diseases in the African," under the initial label of "Nigerian shin disease." Subsequently, it was described in India as well, in 1964, and continues to be a problem in dermatology clinics across the country. It is predominantly a disease of men and has a high prevalence in some geographical regions; up to 3-4% in Madras, South India. Some unique features that distinguish DCPA from banal pustular folliculitis include its peculiar localization to the legs, extreme chronicity, resistance to therapy and inevitable alopecia and atrophy of the involved skin, with little postinflammatory hyper- or hypopigmentation. Further, even in the presence of extensive lesions, there are no systemic features. Coagulase-positive Staphylococcus aureus is known to have a role in the etiology of DCPA, but the exact etiopathogenesis still needs to be elucidated. Immunological postulates such as hypergammaglobulinemia have been put forward to explain the chronicity of the condition. A number of therapeutic agents have been tried in various studies, including cotrimoxazole, psoralen with ultraviolet A (PUVA) therapy, ciprofloxacin, pentoxifylline, rifampicin, dapsone, minocycline and mupirocin (topical) with variable success rates. Although a well-recognized entity in dermatology clinics in tropical countries, DCPA has received little attention in the dermatological literature and has only a few studies to its credit. Its unique clinical picture, unclear etiopathogenesis and resistance to therapy afford a vast scope for further investigation and study.

Modelling the effect of the starter culture on the growth of Staphylococcus aureus in milk.

The competitive growth of a starter culture of lactic acid bacteria (Fresco 1010, Chr. Hansen, Hørsholm, Denmark) and Staphylococcus aureus was studied in milk. The lactic bacteria (LAB) were able to induce an early stationary state in S. aureus. The developed model highlights that the growth of S. aureus is inhibited when the LAB have reached a critical density. The model was tested in different conditions of temperature (from 12 degrees to 25 degrees C), for various inoculum sizes of LAB and S. aureus. The results show that the model accurately quantifies the kinetics of S. aureus as a function of the starter culture.

Enfermedad de Hansen con úlcera plantar y osteítis secundaria por Staphylococcus aureus / No disponible

No disponible

[Evaluation of the effect of Lactobacillus rhamnosus probiotic culture added to yogurt over Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis populations]. / Evaluación del efecto del cultivo probiótico Lactobacillus rhamnosus adicionado a yogurt natural y con probi6ticos comerciales sobre poblaciones de Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes y Salmonella enteritidis.

The effect of different types of probiotics present in yogurt over known populations of Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis was evaluated. The three types of yogurt used were: without added probiotics, with added probiotics (Lactobacillus casei CRL_431 and L. acidophilus CRL_730 CHR HANSEN) and another one with the same probiotics mentioned above and Lactobacillus rhamnosus (LR-35) culture. About 10(9) CFU/ mL of each potentially pathogenic bacteria was added to each type of yogurt tested, and kept in refrigeration at 4 degrees C during its shelf life, about 30 days. Bacterial count was done the initial day and every four days. Results obtained show that there is a difference in the inhibition between yogurts without added probiotics and the commercial yogurt with added probiotics; there is a clear inhibitory effect of the last one over S. aureus, E. coli O157:H7 and Listeria monocytogenes. The yogurt with added probiotics and L. rhamnosus did not show any additional inhibitory effect over the bacteria tested when compared with the yogurt with added probiotics. S. enteritidis could not be evaluated because it was not detectable in any yogurt samples evaluated four days after its inoculation. This study confirms the antagonic effect of probiotic cultures over potentially pathogenic bacteria for human beings and animals that may be present in food. Nevertheless, the use of L. rhamnosus did not produce any additional inhibitory effect.