Residual concentrations of antimicrobial growth promoters in poultry litter favour plasmid conjugation among Escherichia coli.

Considering that plasmid conjugation is a major driver for the dissemination of antimicrobial resistance in bacteria, this study aimed to investigate the effects of residual concentrations of antimicrobial growth promoters (AGPs) in poultry litter on the frequencies of IncFII-FIB plasmid conjugation among Escherichia coli organisms. A 2 × 5 factorial trial was performed in vitro, using two types of litter materials (sugarcane bagasse and wood shavings) and five treatments of litter: non-treated (CON), herbal alkaloid sanguinarine (SANG), AGPs monensin (MON), lincomycin (LCM) and virginiamycin (VIR). E. coli H2332 and E. coli J62 were used as donor and recipient strains, respectively. The presence of residues of monensin, lincomycin and virginiamycin increased the frequency of plasmid conjugation among E. coli in both types of litter materials. On the contrary, sanguinarine significantly reduced the frequency of conjugation among E. coli in sugarcane bagasse litter. The conjugation frequencies were significantly higher in wood shavings compared with sugarcane bagasse only in the presence of AGPs. Considering that the presence of AGPs in the litter can increase the conjugation of IncFII-FIB plasmids carrying antimicrobial resistance genes, the real impact of this phenomenon on the dissemination of antimicrobial resistant bacteria in the poultry production chain must be investigated.

Clinical safety of oral licomycin treatment in Nile tilapia (Oreochromis niloticus) / Segurança clínica do tratamento via oral com lincomicina em tilapias (Oreochromis niloticus)

Lincomycin is a broad-spectrum antimicrobial acting against Gram-positive bacteria, widely used in veterinary medicine. In fish, there are only limited in vitro data, thus requiring the design of effective therapeutic protocols for their use in aquatic organisms. In this context, the objective was to evaluate the clinical safety of lincomycin treatment, administered orally in tilapia, through hematological, biochemical and somatic index evaluation. A total of 136 tilapia (+100g) were randomly distributed in 17 tanks (100L of water, n=8) to constitute the following treatments: TO (control group, not treated with lincomycin); T1, T2, T3 (treated with 10, 20 and 40mg/kg¹ of lincomycin b.w., respectively) and T4 physiological standard (reference values). Eight animals were sampled per treatment in 4 periods: 2, 4 and 8 days post-treatment (DPT), and a group that was treated for 8 days with the drug and then treated only with commercial feed until the 12th day (recovery period). Tilapia treated with lincomycin had no difference in the hematological and leukocyte evaluation, in the hepatic, renal and splenic somatic index. However, they presented a transient increase in the values of ALT, AST, cholesterol, triglycerides and creatinine, which returned to normal levels after the period of recovery (12DPT). Furthermore, an increase in total protein, albumin and globulin levels was observed in treated animals. It is concluded that although there were some transient changes during the experiment, lincomycin has a good clinical safety margin at doses of 10, 20 and 40mg/Kg¹ b.w. for Nile tilapia.

A lincomicina é um antimicrobiano de amplo espectro atuando contra bactérias gram-positivas, amplamente utilizada na medicina veterinária. Em peixes existem apenas dados limitados in-vitro, necessitando assim, de delineamento de protocolos terapêuticos eficazes para seu uso em organismos aquáticos. Desse modo, objetivou-se avaliar a segurança clínica do tratamento com lincomicina, administrada por via oral em tilápias, por meio da avaliação hematológica, bioquímica e indice somático hepático, renal e esplênico. Foram utilizadas 136 tilápias (±100g), distribuídas aleatoriamente em 17 tanques (100L de água, n=8) para constituir as repetições dos diferentes tratamentos: TO (grupo controle, não tratado com lincomicina); T1, T2, T3 (tratados com 10, 20 e 40mg/kg de p.v. de lincomicina, respectivamente) e T4 padrão fisiológico (valores de referência). Oito animais foram amostrados por tratamento em 4 períodos: 2, 4 e 8 dias pós-tratamento (DPT) com lincomicina, e um grupo que foi tratado por 8 dias com o fármaco e após isso tratado apenas com ração comercial até o 12º dia (período de recuperação). Tilápias tratadas com lincomicina não tiveram diferença na avaliação hematológica e leucocitária, no índice somático hepático, renal e esplênico, entretanto, apresentaram um aumento transitório nos valores de ALT, AST, colesterol, triglicérides e creatinina, que retornaram aos níveis normais após o período de recuperação (12DPT). Ademais, foram observados um incremento nos níveis de proteína total, albumina e globulina nos animais tratados. Conclui-se que embora tenha ocorrido algumas alterações transitórias ao decorrer do experimento, a lincomicina apresenta boa margem de segurança clinica nas doses de 10, 20 e 40mg/Kg¹ p.v para tilápia do Nilo.

Informe diário de evidências COVID-19: busca realizada em 17 de junho de 2020 / COVID-19 daily evidence report: search conducted on June 17, 2020

O Informe Diário de Evidências é uma produção do Ministério da Saúde que tem como objetivo acompanhar diariamente as publicações científicas sobre tratamento farmacológico e vacinas para a COVID-19. Dessa forma, são realizadas buscas estruturadas em bases de dados biomédicas, referente ao dia anterior desse informe. Não são incluídos estudos pré-clínicos (in vitro, in vivo, in silico). A frequência dos estudos é demonstrada de acordo com a sua classificação metodológica (revisões sistemáticas, ensaios clínicos randomizados, coortes, entre outros). Para cada estudo é apresentado um resumo com avaliação da qualidade metodológica. Essa avaliação tem por finalidade identificar o grau de certeza/confiança ou o risco de viés de cada estudo. Para tal, são utilizadas ferramentas já validadas e consagradas na literatura científica, na área de saúde baseada em evidências. Cabe ressaltar que o documento tem caráter informativo e não representa uma recomendação oficial do Ministério da Saúde sobre a temática. Foram encontrados 15 artigos.

Assessing the depletion of lincomycin in feathers from treated broiler chickens: a comparison with the concentration of its residues in edible tissues.

Lincomycin is the first antimicrobial agent described for the lincosamide class and it is commonly used for the treatment of infectious enteric and respiratory diseases in poultry. Maximum residue limits (MRLs) in edible tissues have been established for this antimicrobial, however, no regulation has been proposed yet for by-products that are not intended for direct human consumption. Feathers are a by-product from poultry farming that might be used as an ingredient for diets fed to other farm animal species. The presence of antimicrobial residues in them is not monitored in spite of the fact that several studies have proved that they can persist in feathers. Currently though, no evidence has been presented regarding the behaviour of lincomycin in this matrix. Hence, this work intended to assess the depletion of lincomycin residues in feathers of birds treated with therapeutic doses and compare them with those detected in muscle and liver samples. Samples were collected for several days after ceasing treatment from a group of broiler chickens treated with a 25% lincomycin formulation. Methanol and Florisil® columns were used to extract and retain the analyte, and samples were analysed using a triple quadrupole mass spectrometer (API 5500, AB SCIEX™). On day 1 after ceasing treatment, average concentrations of lincomycin detected in feather samples reached up to 8582 µg kg-1 and by day 16, these had only declined by 63%, to an average of 3138 µg kg-1. Lincomycin residues were detected in feathers at every sampling point, even after they were not detectable in edible tissues. Depletion time was 98 days for feathers, considering the LOQ established for the methodology as cut-off value for the calculations. Data showed that lincomycin is highly persistent in feathers, which may result in this matrix becoming a re-entry route for its residues into the food chain.

The prevalence of genotypes that determine resistance to macrolides, lincosamides, and streptogramins B compared with spiramycin susceptibility among erythromycin-resistant Staphylococcus epidermidis.

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, can be regarded as potential reservoirs of resistance genes for pathogenic strains, e.g., Staphylococcus aureus. The aim of this study was to assess the prevalence of different resistance phenotypes to macrolide, lincosamide, and streptogramins B (MLSB) antibiotics among erythromycin-resistant S. epidermidis, together with the evaluation of genes promoting the following different types of MLSB resistance:ermA, ermB, ermC,msrA, mphC, and linA/A'. Susceptibility to spiramycin was also examined. Among 75 erythromycin-resistantS. epidermidis isolates, the most frequent phenotypes were macrolides and streptogramins B (MSB) and constitutive MLSB (cMLSB). Moreover, all strains with the cMLSB phenotype and the majority of inducible MLSB (iMLSB) isolates were resistant to spiramycin, whereas strains with the MSB phenotype were sensitive to this antibiotic. The D-shape zone of inhibition around the clindamycin disc near the spiramycin disc was found for some spiramycin-resistant strains with the iMLSB phenotype, suggesting an induction of resistance to clindamycin by this 16-membered macrolide. The most frequently isolated gene was ermC, irrespective of the MLSB resistance phenotype, whereas the most often noted gene combination wasermC, mphC, linA/A'. The results obtained showed that the genes responsible for different mechanisms of MLSB resistance in S. epidermidis generally coexist, often without the phenotypic expression of each of them.

The prevalence of genotypes that determine resistance to macrolides, lincosamides, and streptogramins B compared with spiramycin susceptibility among erythromycin-resistant Staphylococcus epidermidis

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, can be regarded as potential reservoirs of resistance genes for pathogenic strains, e.g., Staphylococcus aureus. The aim of this study was to assess the prevalence of different resistance phenotypes to macrolide, lincosamide, and streptogramins B (MLSB) antibiotics among erythromycin-resistant S. epidermidis, together with the evaluation of genes promoting the following different types of MLSB resistance:ermA, ermB, ermC,msrA, mphC, and linA/A’. Susceptibility to spiramycin was also examined. Among 75 erythromycin-resistantS. epidermidis isolates, the most frequent phenotypes were macrolides and streptogramins B (MSB) and constitutive MLSB (cMLSB). Moreover, all strains with the cMLSB phenotype and the majority of inducible MLSB (iMLSB) isolates were resistant to spiramycin, whereas strains with the MSB phenotype were sensitive to this antibiotic. The D-shape zone of inhibition around the clindamycin disc near the spiramycin disc was found for some spiramycin-resistant strains with the iMLSB phenotype, suggesting an induction of resistance to clindamycin by this 16-membered macrolide. The most frequently isolated gene was ermC, irrespective of the MLSB resistance phenotype, whereas the most often noted gene combination wasermC, mphC, linA/A’. The results obtained showed that the genes responsible for different mechanisms of MLSB resistance in S. epidermidis generally coexist, often without the phenotypic expression of each of them.

Caracterização filogenética molecular e resistência antimicrobiana de escherichia coli isoladas de caprinos neonatos com diarreia / Molecular-phylogenetic characterization and antimicrobial resistance of Escherichia coli isolated from goats with diarrhea

Neonatal diarrhea determines significant changes in feed conversion, causing productivity loss in caprine herds. The antimicrobial resistance in bacteria is characterized as an important public healthissue; therefore, Escherichia coli may be characterized as an important pathogen due to expressingvirulence mechanisms responsible for significant clinical conditions in humans and animals. Thepresent study evaluated the presence of E. coli among 117 caprine fecal samples and analyzed theisolates for antimicrobial resistance. Suggestive colonies were submitted to biochemical screeningfollowed by genotypic group determination and phylogenetic analysis; further, the sampleswere submitted to antimicrobials susceptibility test. E. coli, Salmonella spp, Shigella sonnei andEnterobacter aerogenes were identified. E. coli isolates were phylogenetically classified as B2 (9/39),D (19/39), B1 (7/39) e A (4/29) groups. The analysis of the isolates also revealed the presence of K99(04/39) and Stx (02/39) virulence factors. Antimicrobial susceptibility test revealed sensitive isolatesto Chloramphenicol, Streptomycin, Amoxicillin and Ciprofloxacin, being all resistant to Lincomycin,Vancomycin and Penicillin. The results support the need of establishing restricted protocols forantimicrobial use, a fundamental procedure for health improvement in Brazilian caprine herds.

A diarreia neonatal determina alterações significativas na conversão alimentar, resultando na queda daprodutividade de caprinos. A resistência antimicrobiana em bactérias caracteriza-se como importanteproblema de saúde pública, assim, a Escherichia coli pode ser caracterizada como importantepatógeno por expressar mecanismos de virulência responsáveis por significativas afecções clínicasem seres humanos e animais. O presente estudo avaliou a presença de E. coli em 117 amostrasfecais de caprinos e analisou a resistência antimicrobiana dos isolados. Colônias sugestivas foramsubmetidas a testes bioquímicos, seguido de determinação do grupo genotípico e análise filogenética;posteriormente foram submetidas à prova de suscetibilidade a antimicrobianos. Foram identificadosisolados de E. coli, Salmonella spp, Shigella sonnei e Enterobacter aerogenes. Isolados de E. coliforam classificados filogeneticamente em B2 (9/39), D (19/39), B1 (7/39) e A (4/29). Os fatores devirulência identificados foram K99 (04/39) e Stx (02/39). À prova de suscetibilidade antimicrobiana,os isolados foram sensíveis a Cloranfenicol, Estreptomicina, Amoxicilina e Ciprofloxacina, sendotodos resistentes à Lincomicina, Vancomicina e Penicilina. Os resultados reforçam a necessidade deestabelecimento de protocolos criteriosos para o uso de antimicrobianos, medida fundamental para oaprimoramento da sanidade dos rebanhos caprinos brasileiros.

Caracterização filogenética molecular e resistência antimicrobiana de escherichia coli isoladas de caprinos neonatos com diarreia / Molecular-phylogenetic characterization and antimicrobial resistance of Escherichia coli isolated from goats with diarrhea

Neonatal diarrhea determines significant changes in feed conversion, causing productivity loss in caprine herds. The antimicrobial resistance in bacteria is characterized as an important public healthissue; therefore, Escherichia coli may be characterized as an important pathogen due to expressingvirulence mechanisms responsible for significant clinical conditions in humans and animals. Thepresent study evaluated the presence of E. coli among 117 caprine fecal samples and analyzed theisolates for antimicrobial resistance. Suggestive colonies were submitted to biochemical screeningfollowed by genotypic group determination and phylogenetic analysis; further, the sampleswere submitted to antimicrobials susceptibility test. E. coli, Salmonella spp, Shigella sonnei andEnterobacter aerogenes were identified. E. coli isolates were phylogenetically classified as B2 (9/39),D (19/39), B1 (7/39) e A (4/29) groups. The analysis of the isolates also revealed the presence of K99(04/39) and Stx (02/39) virulence factors. Antimicrobial susceptibility test revealed sensitive isolatesto Chloramphenicol, Streptomycin, Amoxicillin and Ciprofloxacin, being all resistant to Lincomycin,Vancomycin and Penicillin. The results support the need of establishing restricted protocols forantimicrobial use, a fundamental procedure for health improvement in Brazilian caprine herds.(AU)

A diarreia neonatal determina alterações significativas na conversão alimentar, resultando na queda daprodutividade de caprinos. A resistência antimicrobiana em bactérias caracteriza-se como importanteproblema de saúde pública, assim, a Escherichia coli pode ser caracterizada como importantepatógeno por expressar mecanismos de virulência responsáveis por significativas afecções clínicasem seres humanos e animais. O presente estudo avaliou a presença de E. coli em 117 amostrasfecais de caprinos e analisou a resistência antimicrobiana dos isolados. Colônias sugestivas foramsubmetidas a testes bioquímicos, seguido de determinação do grupo genotípico e análise filogenética;posteriormente foram submetidas à prova de suscetibilidade a antimicrobianos. Foram identificadosisolados de E. coli, Salmonella spp, Shigella sonnei e Enterobacter aerogenes. Isolados de E. coliforam classificados filogeneticamente em B2 (9/39), D (19/39), B1 (7/39) e A (4/29). Os fatores devirulência identificados foram K99 (04/39) e Stx (02/39). À prova de suscetibilidade antimicrobiana,os isolados foram sensíveis a Cloranfenicol, Estreptomicina, Amoxicilina e Ciprofloxacina, sendotodos resistentes à Lincomicina, Vancomicina e Penicilina. Os resultados reforçam a necessidade deestabelecimento de protocolos criteriosos para o uso de antimicrobianos, medida fundamental para oaprimoramento da sanidade dos rebanhos caprinos brasileiros.(AU)

Different assay conditions for detecting the production and release of heat-labile and heat-stable toxins in enterotoxigenic Escherichia coli isolates.

Enterotoxigenic Escherichia coli (ETEC) produce heat-labile (LT) and/or heat-stable enterotoxins (ST). Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. For this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. The presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work.

A controlled pilot study on the efficacy of a low dose antibiotic for the treatment of chronic constipation in patients receiving a high fiber diet.

BACKGROUND AND AIMS: In a previous uncontrolled experiment, oral vancomycin improved the symptoms (S) of chronic constipation (CC). The aim of this 21 day controlled pilot study was to determine if a low lincomycin dose improved the S of CC patients unresponsive to a high fiber diet. METHODS: On days 0-to-10, patients were randomized to 500 mg oral lincomycin + high fiber (L + F) or to placebo + high fiber (P + F). Participants and patients were blinded. From days 10-to-21, patients were continued solely on the high fiber diet. The primary efficacy endpoint was the difference in S between L + F and P + F from days 0-to-21 using a visual analog scale (VAS) calibrated from 0 = severe S to 10 = asymptomatic. RESULTS: The means of all S were significantly improved by L + F but not by P + F. A significant higher proportion of L + F patients increased the VAS > or = 3 points. CONCLUSIONS: The initial course of L facilitated the effect of F probably by its effect on the colon flora. This sequence of flora-altering biologics + F may serve as model to replace chronic use of drugs.

A controlled pilot study on the efficacy of a low dose antibiotic for the treatment of chronic constipation in patients receiving a high fiber diet. / A controlled pilot study on the efficacy of a low dose antibiotic for the treatment of chronic constipation in patients receiving a high fiber diet.

BACKGROUND AND AIMS: In a previous uncontrolled experiment, oral vancomycin improved the symptoms (S) of chronic constipation (CC). The aim of this 21 day controlled pilot study was to determine if a low lincomycin dose improved the S of CC patients unresponsive to a high fiber diet. METHODS: On days 0-to-10, patients were randomized to 500 mg oral lincomycin + high fiber (L + F) or to placebo + high fiber (P + F). Participants and patients were blinded. From days 10-to-21, patients were continued solely on the high fiber diet. The primary efficacy endpoint was the difference in S between L + F and P + F from days 0-to-21 using a visual analog scale (VAS) calibrated from 0 = severe S to 10 = asymptomatic. RESULTS: The means of all S were significantly improved by L + F but not by P + F. A significant higher proportion of L + F patients increased the VAS > or = 3 points. CONCLUSIONS: The initial course of L facilitated the effect of F probably by its effect on the colon flora. This sequence of flora-altering biologics + F may serve as model to replace chronic use of drugs.

A controlled pilot study on the efficacy of a low dose antibiotic for the treatment of chronic constipation in patients receiving a high fiber diet / A controlled pilot study on the efficacy of a low dose antibiotic for the treatment of chronic constipation in patients receiving a high fiber diet.

BACKGROUND AND AIMS: In a previous uncontrolled experiment, oral vancomycin improved the symptoms (S) of chronic constipation (CC). The aim of this 21 day controlled pilot study was to determine if a low lincomycin dose improved the S of CC patients unresponsive to a high fiber diet. METHODS: On days 0-to-10, patients were randomized to 500 mg oral lincomycin + high fiber (L + F) or to placebo + high fiber (P + F). Participants and patients were blinded. From days 10-to-21, patients were continued solely on the high fiber diet. The primary efficacy endpoint was the difference in S between L + F and P + F from days 0-to-21 using a visual analog scale (VAS) calibrated from 0 = severe S to 10 = asymptomatic. RESULTS: The means of all S were significantly improved by L + F but not by P + F. A significant higher proportion of L + F patients increased the VAS > or = 3 points. CONCLUSIONS: The initial course of L facilitated the effect of F probably by its effect on the colon flora. This sequence of flora-altering biologics + F may serve as model to replace chronic use of drugs.

Optimisation and validation of a quantitative and confirmatory method for residues of macrolide antibiotics and lincomycin in kidney by liquid chromatography coupled to mass spectrometry.

A solid phase extraction followed by a liquid chromatography (LC)-tandem mass spectrometry (MS/MS) detection method for the confirmatory analysis of lincomycin (LIN), clindamycin (CLI), tilmicosin (TIM), erythromycin (ERI) and tylosin (TYL) residues in kidney were optimised and validated for monitoring and controlling the use of these antibiotics in food producing-animals. The method optimisation was carried out by testing changes in the extraction buffer pH and in the ammonium/acetonitrile concentrations on SPE eluent solutions. The optimised extraction procedure involved the extraction of the analytes with a pH 8 phosphate buffer, clean-up on a reversed-phase mixed-cation exchange cartridge, followed by the elution of the analytes in a 98:2 acetonitrile/ammonia solution, concentration in air flow and re-dissolved with an 1:1 methanol/water solution. The analytes were detected in an LC-MS/MS system in electrospray positive ionisation mode. The validation was performed according to the European Commission Decision 2002/657/EC. Linearity was established for all analytes using the method of least weighted squares and CCα values ranged from 5.3% to 21.1% higher than the minimum residue limit (MRL) values. The addition levels varied from 0.5 to 1.50 MRL for all analytes, with recoveries exceeding 92.5%. The relative standard deviations (RSD%) in terms of repeatability (n = 54) and reproducibility (n = 108) for all analytes were less than 21.6% and 21.4%, respectively. The uncertainties were calculated by simplified methods using the calibration curve uncertainty and the intermediate precision to obtain the combined measurement uncertainty. The results of the validation process demonstrated that this method is suitable for the quantification and confirmation of antibiotic residues for the Brazilian Residue and Contaminant Control Plan (PNCR).

Pharmacokinetics and bone tissue concentrations of lincomycin following intravenous and intramuscular administrations to cats.

The pharmacokinetic properties and bone concentrations of lincomycin in cats after single intravenous and intramuscular administrations at a dosage rate of 10 mg/kg were investigated. Lincomycin minimum inhibitory concentration (MIC) for some gram-positive strains isolated from clinical cases was determined. Serum lincomycin disposition was best-fitted to a bicompartmental and a monocompartmental open models with first-order elimination after intravenous and intramuscular dosing, respectively. After intravenous administration, distribution was rapid (T(1/2(d)) = 0.22 ± 0.09 h) and wide as reflected by the volume of distribution (V((d(ss)))) of 1.24 ± 0.08 L/kg. Plasma clearance was 0.28 ± 0.09 L/h · kg and elimination half-life (T(1/2)) 3.56 ± 0.62 h. Peak serum concentration (C(max)), T(max), and bioavailability for the intramuscular administration were 7.97 ± 2.31 µg/mL, 0.12 ± 0.05 h, and 82.55 ± 23.64%, respectively. Thirty to 45 min after intravenous administration, lincomycin bone concentrations were 9.31 ± 1.75 µg/mL. At the same time after intramuscular administration, bone concentrations were 3.53 ± 0.28 µg/mL. The corresponding bone/serum ratios were 0.77 ± 0.04 (intravenous) and 0.69 ± 0.18 (intramuscular). Lincomycin MIC for Staphylococcus spp. ranged from 0.25 to 16 µg/mL and for Streptococcus spp. from 0.25 to 8 µg/mL.

Effect of extender supplementation with various antimicrobial agents on viability of Brucella ovis and Actinobacillus seminis in cryopreserved ovine semen.

The objective was to determine the effectiveness of various antimicrobial agents added to semen extender for inactivation of B. ovis or A. seminis in ovine semen after cryopreservation. In Experiment 1, 20 ejaculates from a crossbred ram infected with B. ovis were cryopreserved in Tris-based extenders with various antimicrobial agents: (I) control without antibiotics, (II) with penicillin and streptomycin (1000 IU/mL and 1 mg/mL, respectively), (III) lincomycin (0.15 mg/mL), (IV) sulphadiazine (0.60 mg/mL), and (V) gentamicin sulphate (0.25 mg/mL). Semen was stored in 0.25 mL straws at a final concentration of 150 × 10(6) spermatozoa/mL. After thawing (37 °C for 30 s), sperm total motility (TM), sperm morphology, integrity of sperm membranes, and bacterial growth were assessed. In Experiment 2, six B. ovis isolates were separately inoculated into aliquots of a fresh ejaculate from a B. ovis-free ram. Mock inoculated semen was processed for cryopreservation using the five extenders described above, and bacteriologically evaluated after thawing. In Experiment 3, sensitivity of A. seminis to the same antimicrobial agents was evaluated by inoculating an ejaculate from an A. seminis and B. ovis-free ram. There were no significant differences among treatments in post-thawing sperm parameters. B. ovis was isolated from 100% (20/20), 0% (0/20), 95% (19/20), 100% (20/20), and 5% (1/20) of semen samples diluted in tris-based extender of untreated (I) and treated semen samples with antimicrobial agents II, III, IV, and V, respectively. Frequencies of isolation from samples treated with antimicrobial agent II and V were significantly lower than untreated ones (P < 0.05). There were no significant differences in the profile of antimicrobial resistance of different B. ovis isolates. A. seminis had a similar sensitivity to the antimicrobial agents. We concluded that addition of a combination of penicillin and streptomycin or gentamicin alone to ram semen cryo-extenders inactivated B. ovis and A. seminis.

Heat stress results in loss of chloroplast Cu/Zn superoxide dismutase and increased damage to Photosystem II in combined drought-heat stressed Lotus japonicus.

Drought and heat stress have been studied extensively in plants, but most reports involve analysis of response to only one of these stresses. Studies in which both stresses were studied in combination have less commonly been reported. We report the combined effect of drought and heat stress on Photosystem II (PSII) of Lotus japonicus cv. Gifu plants. Photochemistry of PSII was not affected by drought or heat stress alone, but the two stresses together decreased PSII activity as determined by fluorescence emission. Heat stress alone resulted in degradation of D1 and CP47 proteins, and D2 protein was also degraded by combined drought-heat stress. None of these proteins were degraded by drought stress alone. Drought alone induced accumulation of hydrogen peroxide but the drought-heat combination led to an increase in superoxide levels and a decrease in hydrogen peroxide levels. Furthermore, combined drought-heat stress was correlated with an increase in oxidative damage as determined by increased levels of thiobarbituric acid reactive substances. Heat also induced degradation of chloroplast Cu/Zn superoxide dismutase (SOD: EC 1.15.1.1) as shown by reduced protein levels and isozyme-specific SOD activity. Loss of Cu/Zn SOD and induction of catalase (CAT: EC 1.11.1.6) activity would explain the altered balance between hydrogen peroxide and superoxide in response to drought vs combined drought-heat stress. Degradation of PSII could thus be caused by the loss of components of chloroplast antioxidant defence systems and subsequent decreased function of PSII. A possible explanation for energy dissipation by L. japonicus under stress conditions is discussed.

Pruebas de sensibilidad frente a agentes anti microbianos en cepas de Brachyspira pilosicoli aisladas a partir de ponedoras comerciales en Colombia / Antimicrobial susceptibility test in Brachyspira pilosicoli strains isolated from commercial layers farms in Colombia

Las espiroquetas intestinales del género Brachyspira ocasionan enfermedades importantes en porcinos y aves. Se ha evidenciado un problema de incremento en la presentación de cepas resistentes a los antimicrobianos utilizados normalmente para tratar las espiroquetosis intestinales en porcinos, y esto podría ser aplicable a los aislamientos de aves. Hay muypocos reportes de sensibilidad antimicrobiana in vitro de cepas de Brachyspira spp. aisladas en aves. En este estudio se evaluó la sensibilidad de doce aislamientos de Brachyspira pilosicoli obtenidos de granjas de ponedoras comerciales a los agentes antimicrobianos tiamulina, tilosina y lincomicina, y se estableció la concentración mínima inhibitoria (CMI)mediante la técnica de dilución en agar. Todas las bacterias analizadas fueron sensibles a tiamulina (CMI≤0,1 μg/ml) y lincomicina (CMI 1 μg/ml) y resistentes a tilosina (CMI 5 μg/ml).

Intestinal Spirochaetes of the genus Brachyspira cause important diseases in swine and poultry. An increasing problem in the presentation of resistant strains to the antimicrobial drugs usually used to treat the intestinal spirochaetosis in swine has been evidenced and this could be applicable to the isolations from poultry. There are very few reports of in vitro antimicrobialsusceptibility of Brachyspira spp. isolated from birds. In this study the antimicrobial susceptibility of twelve Brachyspira pilosicoli isolates obtain from commercial layers was evaluated against tiamulin, tylosin and lincomycin establishing the Minimum Inhibitory Concentration (MIC) by agar dilution technique. All bacteria analyzed were sensitive to tiamulin (MIC ≤0,1μg/ml), and lincomycin (MIC 1μg/ml) and resistant to tylosin (MIC 5μg/ml).

Effect of lincomycin treatment of root surface in dental replantation: a study in rats / Efeito da lincomicina como tratamento da superfície radicular no reimplante de dentes: estudo em ratos

Purpose: The purpose of studies on antibiotics used topically on the root surface of avulsed teeth is to evaluate their antiresorptive properties which favor the repair of the periodontal ligament and the reestablishment of the dentoalveolar articulation. The aim of the present study was to determine the effect of lincomycin treatment of the root surface on tooth replantation. Methods: Ten rats were distributed into two groups (I - control; II - experimental). The right maxillary incisor of the animals was extracted and stored in milk for 30 min. The tooth in group I was rinsed with normal saline and replanted; in group II, the incisor was immersed in lincomycin for 5 min before replantation. The animals were euthanized on the 21st day postoperative. The right hemimaxilla was submitted to histological sectioning and stained with H&E for microscopic evaluation. Results: Group I: the periodontal ligament appeared dispersed, with moderate to intense lymphoplasmacytic infiltrate, and dentoalveolar articulation was not reestablished. Group II: complete repair of the ligament was evident, and there were few inflammatory cells and small areas of inflammatory resorption and ankylosis. Conclusion: The use of lincomycin allowed the repair of the periodontal ligament and reduced inflammation. There were still areas of inflammatory resorption and ankylosis.

Objetivo: Estudos sobre antibióticos usados topicamente na superfície radicular de dentes avulsionados buscam avaliar suas propriedades anti-reabsortivas que favoreçam o reparo do ligamento periodontal e o restabelecimento da articulação dentoalveolar. Neste mesmo propósito, esta pesquisa avaliou o efeito da lincomicina na superfície radicular, antes do reimplante. Metodologia: Dez ratos foram distribuídos em dois grupos de 05 animais (I - controle e II - experimental). O incisivo superior direito dos animais foi extraído e estocado em leite por 30 min. Em seguida, no grupo I, os dentes foram irrigados com soro fisiológico e reimplantados; no grupo II, os incisivos foram imersos em lincomicina por 5 min, antes do reimplante. Os animais foram eutanasiados no 21º dia pós-operatório e a hemimaxila direita submetida a cortes histológicos, corados em HE, para avaliação microscópica. Resultados: No grupo I, o ligamento periodontal apresentou-se disperso, com infiltrado linfoplasmocitário moderado a intenso e a articulação dentoalveolar não foi restabelecida; no grupo II, notou-se completo reparo do ligamento, poucas células inflamatórias e pequenas áreas de reabsorção inflamatória e anquilose. Conclusões: O uso tópico da lincomicina no tratamento da superfície radicular promoveu o reparo do ligamento periodontal, reduziu o processo inflamatório, mas ainda foram observadas áreas de reabsorção inflamatória e anquilose.