The gene encoding resistance to β-lactam antibiotics in the staphylococci is found on the chromosome in a genomic island designated Staphylococcal Chromosome Cassette mec or SCCmec. In addition to the resistance gene, mecA, SCCmec also contains site specific recombinase genes, ccrAB, that are capable of catalyzing the chromosomal excision and integration of SCCmec. The increasing prevalence of methicillin-resistant Staphylococcus aureus infections may be due, in part, to the transfer of SCCmec into successful methicillin-sensitive S. aureus lineages. In this work we attempt to better characterize the factors associated with SCCmec transfer, beginning with CcrAB-mediated SCCmec excision in a collection of MRSA containing type IV SCCmec. CcrAB-mediated excision of type IV SCCmec was not demonstrated for all strains tested, as a subset of S. aureus strains with type IV SCCmed did not excise their element. These strains are all highly related and represent a lineage of successful community associated pathogens. In addition, the inability to excise SCCmec in these strains is associated with the presence of a presumptive mobile element containing the gene for staphylococcal enterotoxin H (seh) immediately outside of SCCmec on the chromosome. Staphylococcus aureus strain USA300 contains SCCmec type IV and a genomic island containing an arginine deiminase pathway, known as ACME, inserted adjacent to one another in the SCCmec chromosomal attachment site. Each element was site-specifically excised from the chromosome by CcrAB, resulting in two independent, extra-chromosomal, circularized elements. Therefore the presence of ACME did not disrupt SCCmec excision.Next, we describe three MRSA strains that become resistant to vancomyein during passage on increasing concentrations of the drug. In each case, mecA was lost during passage. Strain 5836VR lost mecA by the site-specific chromosomal excision of SCCmec while the other two strains (3130VR and VP32) deleted portions of their SCCmec elements in a manner that appears to involve IS431. Conversion to vancomycin resistance caused a decrease in growth rate that was partially compensated for by deletion of mecA. In mixed culture competition experiements, vancomycin resistant strains that lacked mecA readily out-competed their mecA-containing counterparts, suggesting that the loss of mecA during conversion to vancomycin resistance was advantageous to the organism.Finally, we examined the genetic structure surrounding the SCCmec attachment site in a diverse collection of methicillin-sensitive S. aureus isolates. This region of the chromosome varies greatly from strain to strain and appaers to be prone to recomination. Open reading frames found in this region were homologous to enterotoxins, restriction-modification enzymes, and transposases. Several open reading frames that have not been previously reported in staphylococci were also present in this region. 28 out of the 42 isolates examined did not contain the attachment site sequence found in S. aureus isolates known to be capable of CcrAB-mediated SCCmec integration or excision. This may indicate that these strains do not contain a functional attachment site and therefore may not have the potential to acquire SCCmec by CcrAB-mediated recombination.

Antibiotic resistance threatens to throw mankind back into an era when infectious disease was the predominant cause of death. In an effort to mitigate this danger, we targeted ErmC’ and KsgA. Both methylate N6-adenosine of ribosomal RNA, though each serve different roles in their bacterial host. ErmC’ dimethylates A2058 on 23S rRNA, conferring resistance to MLSB antibiotics (macrolides, lincosamides, streptogramin B). KsgA aids in ribosome assembly, binding inactive 30S until dimethylating A1518/A1519 of 16S rRNA. Like most methyltransferases, ErmC’ and KsgA use cofactor S-adenosylmethionine (SAM) as their methyl source, which binds adjacent to their specific adenosine substrate. ErmC’ inhibitors could restore MLSB antibiotics against infections with this resistance mechanism. KsgA inhibitors could form novel antibiotics that stall 30S assembly. Previous studies reported a potent ErmC’ inhibitor, N6-cyclopentyl adenosine (1), binding to the substrate pocket with cyclopentyl bridging into the SAM pocket. We expanded this study by synthesizing 1 and 22 other N6-substituted analogs to explore more favorable interactions within the SAM pocket. When these compounds (1mM) were screened against ErmC’ and KsgA, some showed greater inhibition than 1. Two of these inhibitors that were crystallized with ErmC’, N6-8-octylamine adenosine (2.60Å) and N6-phenethyl adenosine (2.40Å), unexpectedly docked into the SAM pocket with their 5’-C pointing towards the substrate pocket. New compounds were made to exploit this orientation by adding substituents off the 5’-C to probe the substrate pocket. Through a five step synthesis, the 5’-OH of 1 was substituted with an amine linked to benzyl (30), phenethyl (31), propylphenyl (32) or butylphenyl (33). When 30-33 were screened using 20μM SAM, ErmC’ showed greater inhibition (relative to 1), while KsgA showed virtually none. However, when ErmC’ was tested using 0.5μM SAM, inhibition from 30-33 was nearly unchanged, whereas 1 became significantly more potent than 30-33, suggesting 30-33 were not binding to the SAM pocket. Preliminary data showed that raising 23S concentrations lowered inhibition from 32-33, while inhibition from 1, 30 and 31 was nearly unchanged, suggesting that at least 32-33 bound within the substrate pocket.

The purpose of this study was to determine the changes in prescribing habits of active members of American Association of Endodontics (AAE) with regards to antibiotics in comparison to the findings reported by Yingling et al. in 1999. The invitations to take the online survey were sent via email to 2593 active members. A response rate of 37.75% was obtained. It was determined to be adequate for analysis and for comparison to the results obtained by Yingling et al. Comparisons between the percentages shown in this survey and the previous survey were tested using a z-test. An ANOVA model was used to determine the relationships between predictive factors and the number of prescriptions written. The change in distribution of respondents was notable with an increase in younger clinicians (25% in 1999 to 36% at present). They were more likely to be in private practice and much less in part-time academic and private practice setting. The number of patients being seen per week and the number of prescriptions written per week also decreased in comparison (p<0.001). For all the considered factors, it was also noted that board certified endodontists were prescribing less antibiotics per week. A positive correlation was noted for number of years in practice (p=0.0006), type of practice (p<0.001) and number of prescriptions written per week. Changes in choice of antibiotics were also noted. There was a decrease in use of Penicillin (61.48% to 43%), an increase in the use of Amoxicillin (27.5% to 37.6%), and an increase in use clindamycin (45.3% to 64%) for patients with no medical allergies. As for patients with medical allergies, there was a steep incline in the use of clindamycin (56.03% to 90.3%) as first choice to an increase in azithromycin (7.4% to 38%) as a second choice. An improved trend was noted with a significant decrease in use of antibiotics in managing most of the endodontic scenarios given. Antibiotic use in cases of irreversible pulpitis significantly dropped from 16.76% to 12% (p<0.05); in necrotic pulps with acute apical periodontitis with no swelling, a significant decline from 53.9% to 28.3% (p<0.001); significant decreases were also noted for necrotic pulp with chronic apical periodontitis with no/mild symptoms, 18.8% to 16.1% (p=0.029), and necrotic pulp with acute apical periodontitis with swelling and mod/severe symptoms, 99.2% to 92.4% (p<0.001). An exception was noted for necrotic pulp with chronic apical periodontitis with a sinus tract where there was a significant increase in antibiotic use from 11.9% to 29.1% (p<0.001). Many clinicians (19%) were still giving antibiotics due to soliciting of patients and referring general dentists in fear of losing referrals. A disturbing find is that 50% of the respondents were using antibiotics to manage post treatment flare-ups and pain, while 13% were using antibiotics for inter-appointment pain. As for prophylactic antibiotics, most clinicians were aware of the new AHA/ADA guidelines and were abiding by them. Most of the clinicians responding to survey were choosing the appropriate antibiotics and regimen (i.e. dosage, loading dose, and duration). Although there is an improvement in trends, it has to be noted that there is still an indiscriminate and overuse of antibiotics at large. There needs to be greater improvement in the use of antibiotics in endodontics, and a group effort as a specialty is needed in halting this alarming problem of antibiotic resistance globally.

Introduction: Southeast Asia has among the highest rates of antibiotic resistance worldwide, particularly in Indonesia, where paediatricians prescribed antibiotics to 94% of children, knowing that the infection was viral. Relevance: There is a gap in understanding of the reasons behind the irrational use of antibiotics by healthcare professionals and patients. Aim: This research aims to explore factors that influence the use of antibiotics and knowledge about antibiotic resistance in Jakarta, Indonesia. Methods: In December 2014, the researcher conducted thirteen semi-structured interviews with four stakeholder groups, which are involved in the “Smart Use of Antibiotics” campaign in Jakarta. Qualitative Content Analysis was used to identify the theme “unite our voice to address antibiotic resistance from all angles” as well as the five categories: Education, Media, Policy, Culture and Trust. Results: Each category presented one factor, which was divided into the sub-factors education of patients and professionals; online and offline media; policy and guidelines, drug availability and accessibility and stakeholder involvement; habit and behaviour, doctor-patient relationship, environment / surroundings; and trust in the system, in the healthcare professionals, among professionals and in medicine. Conclusion: All stakeholders need to unite their voices together to achieve a smarter use of antibiotics and increase the knowledge about antibiotic resistance.

Streptococcus pneumoniae is a leading cause of pneumonia, bacteremia, meningitis, otitis media and sinusitis, and is responsible for significant morbidity and mortality worldwide. The burden of pneumococcal disease has been greatly impacted by the high prevalence of HIV, especially in developing countries. Macrolides are commonly used for the treatment of pneumococcal infections with the resulting effect of increasing resistance. Pneumococci develop resistance to macrolides predominantly by two mechanisms; target modification and drug efflux. Target modification occurs through the acquisition of an erm(B) gene (MLSB phenotype) or through ribosomal mutation, and drug efflux occurs through the acquisition of a mef(A) gene (M phenotype). Alternative protein synthesis-inhibiting antibiotics such as linezolid and telithromycin have been developed in response to the increasing level of antibiotic resistance. In this study, novel mechanisms of resistance to protein synthesis-inhibiting antibiotics, and the current prevalence and epidemiology of macrolide resistance in South Africa were investigated. Two clinical isolates of S. pneumoniae resistant to macrolides, linezolid and chloramphenicol were identified in the PROTEKT surveillance study and the ABCs program of the CDC. The isolates were found to each contain a 6 bp deletion, resulting in the deletion of two amino acids from a highly conserved region of ribosomal protein L4 (64PWRQ67 to 64P_Q67 and 67QKGT70 to 67Q_T70). The genes encoding the mutant ribosomal proteins transformed susceptible strain R6 to macrolide, linezolid and chloramphenicol resistance, proving that the ii deletions conferred the resistance on the isolates, and indicating that these antibiotics share a common binding site. Growth studies of the R6 transformants showed increased mass doubling times, suggesting that the L4 mutations were associated with a fitness cost, but the original strains showed evidence of fitness compensation. The L4 mutations in these isolates represent a novel mechanism of cross-resistance to macrolides, linezolid and chloramphenicol. A macrolide-resistant clinical isolate of S. pneumoniae with mutations in 23S rRNA showed a heterogeneous phenotype and genotype. A mutant gene encoding 23S rRNA from this isolate transformed susceptible strain R6 to resistance. Transformants displayed similar heterogeneity to the isolate. Culture of resistant strain R6 in the presence of antibiotic maintained resistance, however culture of the strain in the absence of antibiotic pressure resulted in a reversion to susceptibility. By DNA sequencing, gene conversion was shown to occur between the wild-type and mutant 23S rRNA alleles. Growth studies indicated that the resistant phenotype was associated with a fitness cost. Therefore, under antibiotic selective pressure alleles converted to the mutant form, and in the absence of selective pressure alleles reverted to wild-type, in order to regain fitness. Through gene conversion the pneumococcus has the ability to rapidly adapt to the environment, with implications for susceptibility testing and patient treatment. A rare clinical isolate of S. pneumoniae, highly resistant to telithromycin, was received from the Canadian Bacterial Surveillance Network and was investigated for the mechanism of resistance. The isolate was found to contain an erm(B) gene iii with a truncated control peptide, as well as a mutant ribosomal protein L4, containing a number of mutations. Transformation of susceptible strain PC13, containing a wild-type erm(B) gene, with the mutant erm(B) gene decreased the susceptibility of PC13 to telithromycin, but did not confer high-level resistance. Transformation of PC13 with the mutant L4 gene or a fragment of the L4 gene containing only the 69GTG71 to TPS mutation, conferred high-level resistance on PC13. In contrast, transformation of R6, which did not contain an erm(B) gene, with the L4 gene or L4 fragment only conferred reduced telithromycin susceptibility. High-level telithromycin resistance was therefore conferred by a combination of an erm(B) gene with a 69GTG71 to TPS mutation in a highly conserved region of ribosomal protein L4. The combination of mechanisms inhibited the binding of telithromycin to the ribosome, whereas neither mechanism individually was sufficient. A telithromycin-resistant clinical isolate of S. pneumoniae was received from the PROTEKT surveillance study and was investigated for the resistance mechanism. The isolate was found to contain a 136 bp deletion in the regulatory region of erm(B). This mutant gene was shown, by transformation studies, to confer resistance on susceptible strain PC13. Expression of erm(B) on the transcriptional level was quantified by real-time reverse transcription PCR. In the presence of erythromycin and telithromycin, erm(B) expression was significantly higher in the mutant PC13 strain than the wild-type strain. Growth studies showed that the mutant PC13 strain had a shorter lag phase than the wild-type strain in the presence of erythromycin. Telithromycin resistance was conferred by the mutant iv erm(B) gene that was expressed at a higher level than the wild-type gene, most likely resulting in higher ribosomal methylation levels sufficient to hinder telithromycin binding. Macrolide resistance in invasive pneumococcal disease in South Africa for the period 2000 to 2005 was investigated through a national laboratory-based surveillance system. Viable isolates (n=15982) collected during the six-year period were phenotypically characterised, by determination of MICs and serotyping. Two hundred and sixty random isolates from 2005 were genotypically screened for the presence of erm(B) and mef(A). Macrolide resistance increased significantly from 9% in 2000 to 14% in 2005. Resistant isolates were received from all provinces of South Africa, with Gauteng and the Western Cape having the highest incidence. Serotype 14 was the most common macrolide-resistant serotype and 96% of macrolide-resistant isolates in 2005 were serotypes included in the 7-valent pneumococcal conjugate vaccine and serotype 6A. Macrolide resistance was significantly higher in children <5 than in individuals 5 years and older. The majority of strains (75%) over the six-year period displayed the MLSB phenotype. Of the 260 strains genotypically screened, 57% were positive for erm(B), 27% were positive for mef(A), 15% contained both erm(B) and mef(A), and 1% were negative for both genes and were found to contain ribosomal mutations. Eighty percent of isolates containing both erm(B) and mef(A) were serotype 19F and were found to be clonal by PFGE and MLST. These multidrug-resistant isolates were related to the Taiwan19F-14 global clone. v Many protein synthesis-inhibiting antibiotics share overlapping binding sites on the large ribosomal subunit. Alterations in 23S rRNA and ribosomal proteins L4 and L22, within the binding pocket, confer resistance and often cross-resistance to many of these antibiotics. The ability of the pneumococcus to develop resistance and the global spread of resistant strains highlights the importance of monitoring resistance levels and understanding resistance mechanisms.

Le développement de composés de coordination biologiquement actifs (antimicrobiens, les anti-inflammatoires, les antifongiques, les anti-oxydants et les anticancéreux) est un domaine de la chimie inorganique en évolution rapide, susceptible d'avoir un impact direct sur l'amélioration de la qualité de la vie. Les complexes métallo-antibiotique tirent parti de l'effet synergique pour aboutir à une activité pharmacologique améliorée. La reconnaissance du rôle des ions métalliques dans les systèmes biologiques et dans le traitement de diverses maladies attire l'attention sur les avantages d'étudier l'interaction des ions métalliques avec les molécules de médicaments organiques. Dans la continuité avec les travaux précédents de l’équipe, nous nous intéressons à la synthèse de nouvelles familles de complexes métaux-antibiotiques associant l’activité antiseptique d’un ion métallique à un ou deux types de molécules bioactives. Leurs actions additives doivent avoir un effet synergique et conduire à des traitements plus efficaces et devraient fortement minimiser les risques d'apparition de bactéries mutantes. Au cours de ce travail, nous avons réussi à synthétiser le premier complexe métal-antibiotique associant deux types d'antibiotiques différents comme ligands du Zn(II). Des études comparatives montrent qu'il a une meilleure activité antibactérienne contre E. Coli, E. Aureus, E. Feacalis que les antibiotiques parents et les complexes ne contenant qu'un seul de ces antibiotiques. Cela ouvre un nouveau concept appelé « Assemblage de Biomolécules Multi-actifs, ABM ». De plus, nous décrivons la synthèse et la caractérisation de nouveaux ligands antimicrobiens trifluorométhylés / Development of novel coordination complexes with diverse biological activities (antimicrobial, anti-inflammatory, antifungal, antioxidant and anticancer) is a rapidly evolving field of inorganic chemistry with potential direct impact on quality of life. Metal–drug complexes are of increasing interest in bioinorganic chemistry, leveraging the synergistic effect to lead to compounds with improved pharmacological activity. The recognition of the role of metal ions in biological systems and in treatment of various diseases calls attention to the benefits of studying the interaction of metal ions with organic drug molecules. In continuation with previous works of team, we focus here on the synthesis of new families of metal-antibiotic complexes associating, on one single-molecule, the antiseptic activity of a metal ion with the bioactivity of one or two type of bioactive molecules. Their additive actions have a synergetic effect and lead to more effective and shorter treatments and should strongly minimize the risks for appearance of bacteria mutants. In this work, we succeeded to synthesis the first metal-antibiotic complex associating two types of different antibiotic as ligands with Zn(II). The structure in the solid state of this new complex was established together with the studies of the chemical-physical properties. Comparative studies show it has a better antibacterial activity against (E.Coli, E,Aureus, E.Feacalis ) than parent antibiotics and complexes with only one of the antibiotic. This open a new concept named as Multi-Active Biomolecule Assembly. Moreover, the synthesis and characterisation of new trifluorométhylated antimicrobial ligands are described

ABSTRACT Introduction Invasive pneumococcal disease (IPD) is an important cause of morbidity and mortality in many parts of the world. It is estimated that pneumococcal disease causes more than one million-childhood deaths every year and the burden of disease is greater in developing countries. The main aim of this study was to analyze risk factors associated with mortality in invasive pneumococcal disease in all ages in South Africa. Materials and Methods We performed an analytical cross-sectional analysis of secondary data from national population-based surveillance for invasive Streptococcus pneumoniae infection in South Africa. The study period was 1 January 2003 to 31 December 2005, and the mortality analysis used a subset of laboratory-confirmed cases who had a completed case report form and available mortality data. Multiple logistic regression models were constructed to identify risk factors significantly associated with the increased risk of death in patients with invasive pneumococcal disease. Separate models were used to evaluate risk factors for death in patients with meningitis and those with other IPD. Results There were 1154 (24%) cases of Streptococcus pneumoniae meningitis and 3736 (76%) cases of other invasive disease. The overall case fatality rate was 1360/4890 (27.8%) of which 911 (67%) patients died within 2 days of admission and 449 (33%) died between 2 days and 30 days of admission. Variables associated with mortality in a logistic regression analysis of all IPD patients included meningitis (OR 2.8, CI 1.9 – 3.9, P=<0.001), HIV-infection (OR 2.8, CI 1.6 – 4.6, P=<0.001), acute severe illness measured by Pitt bacteraemia score >=4 (OR 4.7, CI 2.8 – 7.7, P=<0.001) and prior antibiotic use within 2 months before first positive culture (OR 2.1, CI 1.4 – 3.1, P=<0.001). In addition to this children less than 1 year and adults ≥45 years were more likely to die compared to other age groups. Patients from Western Cape Province were significantly less likely to die (OR 0.27, CI 0.15 – 0.50, P=<0.001) compared to other provinces. Amongst HIV-positive patients severe immunosuppression (low CD4+ count) was a risk factor for death. Risk factors for death were similar in patients with other IPD and meningitis except for HIV which was associated with death in the meningitis group but not in the other IPD group. Antibiotic resistance and vaccine-serotype disease were not associated with increased risk of death. Discussion and Conclusions IPD is associated with a high mortality in South Africa. Our findings of increased risk of death in HIV-positive patients especially those with low CD4+ count are of importance given the high prevalence of HIV amongst patients with IPD. Introduction of the pneumococcal conjugate vaccine as part of the national expanded program for immunization (EPI) and ensuring access to antiretroviral therapy for HIV-positive patients where indicated should be prioritized.

A literatura apresenta vários artigos que estudam o tipo e a frequência de alterações bucais em pessoas transplantadas renais, mas é escassa em pesquisas que proporcionem evidências científicas sobre o risco de tratamento odontológico invasivo induzir infecção local ou à distância em receptores de transplante. A escassez de estudos que abordam manejo clínico em procedimentos odontológicos invasivos em pacientes transplantados reflete o empirismo e a falta de homogeneidade nas recomendações das equipes transplantadoras em relação ao manejo odontológico ideal do indivíduo receptor de transplante renal. Este volume apresenta um compilado de três trabalhos científicos que abordaram manejo do indivíduo transplantado renal e a avaliação do desfecho clínico após procedimentos odontológicos invasivos. As pesquisas foram executadas no Centro de Atendimento a Pacientes Especiais (CAPE) da Faculdade de Odontologia da USP. Todas tiveram aprovação do comitê de ética em pesquisa. A primeira pesquisa buscou conhecer, por meio de questionário, as condutas dos cirurgiões dentistas frente ao tratamento odontológico de pacientes transplantados renais. O segundo estudo avaliou retrospectivamente a incidência de complicações após exodontias em pacientes transplantados renais, realizadas no CAPE, por diferentes dentistas, que foram precedidas ou não por antibioticoterapia profilática. O terceiro estudo teve por objetivo avaliar a reparação alveolar após extrações de dentes erupcionados de forma prospectiva, em pacientes transplantados e controles, sem receberem antibioticoterapia profilática. Os resultados mostraram que a maioria dos dentistas entrevistados se sentem inseguros em realizar tratamento odontológico em pacientes transplantados renais e prescrevem antibiótico profilático excessivamente, e com posologia empírica. Foi constatado por meio do estudo retrospectivo que o uso ou não de antibiótico profilático antes de exodontias em indivíduos transplantados renais não afeta o desfecho pós-operatório. Por fim, os resultados do terceiro estudo evidenciaram que não há diferença na epitelização e no reparo alveolar pós-exodôntico entre indivíduos transplantados renais e não transplantados, quando submetidos à exodontias simples, sem o uso de antibiótico profilático. / The literature presents several papers regarding type and frequency of oral manifestations in renal transplant recipients, but there is a lack of studies that give scientific evidence about the risk of invasive dental treatment to induce local or distant site infection in renal transplant individuals. The lack of studies that focus on clinic management in invasive dental procedures reflects the empiricism and lack of standardization on the recommendations given by the transplant team regarding the ideal dental management of the renal transplant recipient. This volume presents a compilation of three scientific papers that approach the management of renal transplant recipient and the assessment of clinical outcomes after invasive dental procedures. The researches were performed at the Special Care Dentistry Center (SCDC), of School of Dentistry, University of Sao Paulo. All studies had ethical approval. The first study sought to know, through a questionnaire, the conducts of dentists regarding dental treatment on renal transplant recipients. The second was a retrospective study, that assessed post-operative complications following dental extractions performed at SCDC, that was preceded or not by antibiotic prophylaxis. The third was a prospective study, which assessed the socket healing after dental extractions of erupted teeth, on renal transplant recipients and control individuals, without antibiotic prophylaxis. The results show that most dentists interviewed feel insecure on performing dental treatment on renal transplanted patients as these practitioners prescribe prophylactic antibiotics excessively and based on empirical therapeutic posology. It was verified through the retrospective study that the antibiotic prophylactic prescription or non-prescription preceding an invasive dental procedure does not affect the post-operative outcome for renal transplant recipients. Finally, the results of the third study evidenced that there is no difference in post-extraction epithelization and thus healing between renal transplant recipients and non-transplanted individuals, without using antibiotic prophylaxis.

Plasmids are small circular DNA molecules within bacterial cells that are separated from the bacterial chromosome and replicate independently. Also, they play a crucial role in the dissemination of antibiotic resistance genes among bacteria through horizontal gene transfer. They can be present in many copies within host cell, which is known as plasmid copy number. Plasmids can regulate their own copy number by different mechanisms. Additionally, the selective pressure can also play a pivotal role in determining plasmid copy number. The presence of antibiotics in the surrounding environment can drive variations of plasmid copy number. In this study, we examined plasmid copy number variations of multidrug resistance plasmids in presence of antibiotics by using EvaGreen® - based multiplexed digital droplet PCR. We could observe that cultures of Klebsiella pneumoniae and Escherichia coli harboring multidrug resistance plasmids grown in presence of sub-MIC concentrations of the antibiotics did not show high variations in plasmid copy numbers. On the other hand, mutants of K. pneumoniae selected for increased antibiotic resistance showed high increases in copy number of a multidrug-resistance plasmid.

Este estudo teve como objetivo desenvolver e validar micrométodo simples e sensível para quantificação de cefuroxima plasmática utilizando CLAE-UV com a finalidade de aplicação no monitoramento das concentrações de cefuroxima de pacientes submetidos à cirurgia de revascularização do miocárdio (RM) com CEC no esquema de doses administradas em bolus. Os tempos de retenção para o fármaco e padrão interno (guaifenesina) foram 5,3 e 8,7 minutos respectivamente, com um tempo de corrida de 15 minutos, utilizando coluna de fase reversa C18 (25 cmX4,6 mm, 5 micra) e fase móvel binária constituída de tampão acetato de amônio e trietilamina 0,025 M pH 4,2 e acetonitrila (80:20, v/v), fluxo de 1,0 mL/min, detecção no ultravioleta, &#955;=274nm em sistema isocrático de eluição. A validação deste método analítico investigada através dos limites de confiança apresentou sensibilidade de 0,1 &#181;g/mL (LD) e limite inferior de quantificação (LIQ) de 0,20 &#181;g/mL, linearidade na faixa compreendida 0,2 &#181;g/mL a 200 &#181;g/mL e 4,37% e 2,95% para precisão intra- e inter-dias, respectivamente. Boa exatidão (98,75%) e alta seletividade foram registradas para o método. Através de um protocolo de estudo para antibioticoprofilaxia das infecções cirúrgicas investigaram-se dez pacientes com indicação de cirurgia eletiva de revascularização do miocárdio com circulação extracorpórea. Realizou-se o monitoramento das concentrações plasmáticas após a dose de ataque de 1,5 g, seguido da manutenção realizada através de bolus em tres doses de 0,75 g 6/6 horas. Uma vez que as concentrações plasmáticas de cefuroxima obtidas na sexta hora (vale) foram inferiores à recomendada 16 &#181;g/mL (4x MIC), recomenda-se o aumento de 0,75 g 6/6 horas para 1,5 g mantendo-se o intervalo entre doses de forma a atingir aquela requerida na antibioticoprofilaxia das cirurugias cardíacas. / The objective of the study was to validate na analytical method to determine cefuroxime in plasma by high performance liquid chromatography (HPLC - UV) for clinical purposes in surgical patients submitted to elective cardiac surgery of myocardial revascularization with cardiopulmonary bypass after drug administration as IV boluses. Retention times for the analite and its internal standard (guaifenesin) were 5.3 and 8.7 minutes, respectively; run time was 15 minutes, using a reversed phase colunm C18 (250X4.6 mm, 5 micron) and a binary mobile phase of ammonium acetate/trietilamine 0.025 M pH 4.2 and acetonitrile (80:20, v/v), flow rate 1 mL/min, ultraviolet detector, &#955;=274nm isocratic elution system. Validation of confidence limits presented 0.1 &#181;g/mL sensitivity (LD) and lower limit of quantification (LLOQ) of 0.20 &#181;g/mL, linearity in the range 0.2 &#181;g/mL to 200 &#181;g/mL and 4.37% e 2.95% for intra- / interday precisions, respectively. Good accuracy (98.75%) and high selectivity were obtained. The study protocol for antibiotic prophylaxis of surgical infections was designed for ten patients with indication of elective cardiac surgery of myocardial revascularization with cardiopulmonary bypass. Loading dose of 1.5 g followed by maintenance dose of 0.75 g every six hours by IV boluses were applied and plasma drug monitoring was done. Based on data obtained cefuroxime plasma concentrations at time dose interval were lower than 16 &#181;g/mL (4x MIC) at the trough, consequently it is recommended to increase the maintainance dose from 0.75 g 6/6 h up to 1.5 g 6/6h, to reach the minimum required for the antibiotic prophylaxis of cardiac surgeries.