Evaluation of constitutive and inducible resistance to clindamycin in clinical samples of Staphylococcus aureus from a tertiary hospital

IntroductionInfections caused by methicillin-resistant Staphylococcus aureus (MRSA) have become common in hospitals and the community environment, and this wide resistance has limited patient treatment. Clindamycin (CL) represents an important alternative therapy for infections caused by S. aureus. Antimicrobial susceptibility testing using standard methods may not detect inducible CL resistance. This study was performed to detect the phenotypes of resistance to macrolides-lincosamides-streptogramin B (MLSB) antibiotics, including CL, in clinical samples of S. aureusfrom patients at a tertiary hospital in Santa Maria, State of Rio Grande do Sul, Brazil.MethodsOne hundred and forty clinical isolates were submitted to the disk diffusion induction test (D-test) with an erythromycin (ER) disk positioned at a distance of 20mm from a CL disk. The results were interpreted according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI).ResultsIn this study, 29 (20.7%) of the 140 S. aureus samples were resistant to methicillin (MRSA), and 111 (79.3%) were susceptible to methicillin (MSSA). The constitutive resistance phenotype (cMLSB) was observed in 20 (14.3%) MRSA samples and in 5 (3.6%) MSSA samples, whereas the inducible resistance phenotype (iMLSB) was observed in 3 (2.1%) MRSA samples and in 8 (5.8%) MSSA samples.ConclusionsThe D-test is essential for detecting the iMLSBphenotype because the early identification of this phenotype allows clinicians to choose an appropriate treatment for patients. Furthermore, this test is simple, easy to perform and inexpensive.

Antimicrobial resistance of Helicobacter pylori strains to five antibiotics, including levofloxacin, in Northwestern Turkey

INTRODUCTION: Antibiotic resistance is the main factor that affects the efficacy of current therapeutic regimens against Helicobacter pylori. This study aimed to determine the rates of resistance to efficacy clarithromycin, amoxicillin, tetracycline, levofloxacin and metronidazole among H. pylori strains isolated from Turkish patients with dyspepsia. METHODS: H. pylori was cultured from corpus and antrum biopsies that were collected from patients with dyspeptic symptoms, and the antimicrobial susceptibility of H. pylori was determined using the E-test (clarithromycin, amoxicillin, tetracycline, metronidazole and levofloxacin) according to the EUCAST breakpoints. Point mutations in the 23S rRNA gene of clarithromycin-resistant strains were investigated using real-time PCR. RESULTS: A total of 98 H. pylori strains were isolated, all of which were susceptible to amoxicillin and tetracycline. Of these strains, 36.7% (36/98) were resistant to clarithromycin, 35.5% (34/98) were resistant to metronidazole, and 29.5% (29/98) were resistant to levofloxacin. Multiple resistance was detected in 19.3% of the isolates. The A2143G and A2144G point mutations in the 23S rRNA-encoding gene were found in all 36 (100%) of the clarithromycin-resistant strains. Additionally, the levofloxacin MIC values increased to 32 mg/L in our H. pylori strains. Finally, among the clarithromycin-resistant strains, 27.2% were resistant to levofloxacin, and 45.4% were resistant to metronidazole. CONCLUSIONS: We conclude that treatment failure after clarithromycin- or levofloxacin-based triple therapy is not surprising and that metronidazole is not a reliable agent for the eradication of H. pylori infection in Turkey.

History of insecticide resistance of Triatominae vectors

AbstractIn the last 15 years, different types of Triatominae resistance to different insecticides have been reported; thus, resistance may be more widespread than known, requiring better characterization and delimitation, which was the aim of this review. This review was structured on a literature search of all articles from 1970 to 2015 in the PubMed database that contained the keywords Insecticide resistance and Triatominae . Out of 295 articles screened by title, 33 texts were selected for detailed analysis. Insecticide resistance of Triatomines is a complex phenomenon that has been primarily reported in Argentina and Bolivia, and is caused by different factors (associated or isolated). Insecticide resistance of Triatominae is a characteristic inherited in an autosomal and semi-dominant manner, and is polygenic, being present in both domestic and sylvatic populations. The toxicological profile observed in eggs cannot be transposed to different stages of evolution. Different toxicological profiles exist at macro- and microgeographical levels. The insecticide phenotype has both reproductive and developmental costs. Different physiological mechanisms are involved in resistance. Studies of Triatomine resistance to insecticides highlight three deficiencies in interpreting the obtained results: I) the vast diversity of methodologies, despite the existence of a single guiding protocol; II) the lack of information on the actual impact of resistance ratios in the field; and III) the concept of the susceptibility reference lineage. Research on the biological and behavioral characteristics of each Triatominae species that has evolved resistance is required in relation to the environmental conditions of each region.

Aerobic bacterial profile and antibiotic resistance in patients with diabetic foot infections

ABSTRACTINTRODUCTION: This study aimed to determine the frequencies of bacterial isolates cultured from diabetic foot infections and assess their resistance and susceptibility to commonly used antibiotics.METHODS: This prospective study included 41 patients with diabetic foot lesions. Bacteria were isolated from foot lesions, and their antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method and/or broth method [minimum inhibitory concentration (MIC)].RESULTS: The most common location of ulceration was the toe (54%), followed by the plantar surface (27%) and dorsal portion (19%). A total of 89 bacterial isolates were obtained from 30 patients. The infections were predominantly due to Gram-positive bacteria and polymicrobial bacteremia. The most commonly isolated Gram-positive bacteria were Staphylococcus aureus, followed by Staphylococcus saprophyticus, Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus pneumoniae. The most commonly isolated Gram-negative bacteria were Proteus spp. and Enterobacterspp., followed by Escherichia coli, Pseudomonasspp., and Citrobacterspp. Nine cases of methicillin-resistant Staphylococcus aureus (MRSA) had cefoxitin resistance, and among these MRSA isolates, 3 were resistant to vancomycin with the MIC technique. The antibiotic imipenem was the most effective against both Gram-positive and Gram-negative bacteria, and gentamicin was effective against Gram-negative bacteria.CONCLUSIONS: The present study confirmed the high prevalence of multidrug-resistant pathogens in diabetic foot ulcers. It is necessary to evaluate the different microorganisms infecting the wound and to know the antibiotic susceptibility patterns of the isolates from the infected wound. This knowledge is crucial for planning treatment with the appropriate antibiotics, reducing resistance patterns, and minimizing healthcare costs.

Phenotypic and genotypic profile of pyrethroid resistance in populations of the mosquito Aedes aegypti from Goiânia, Central West Brazil

ABSTRACTINTRODUCTION:The mosquito Aedes aegypti has evolved resistance to pyrethroid insecticides. The present study evaluated Ae. aegypti from Goiânia for the resistant phenotype and for mutations associated with resistance.METHODS:Insecticide dose-response bioassays were conducted on mosquitoes descended from field-collected eggs, and polymerase chain reaction (PCR) was used to genotype 90 individuals at sites implicated in pyrethroid resistance.RESULTS:All mosquito populations displayed high levels of resistance to deltamethrin, as well as high frequencies of the 1016Ile kdr and 1534Cys kdrmutations.CONCLUSIONS:Aedes aegypti populations in the Goiânia area are highly resistant to deltamethrin, presumably due to high frequencies of kdr(knockdown-resistance) mutations.

Antimicrobial resistance profiles and oxacillinase genes in carbapenem-resistant Acinetobacter baumannii isolated from hospitalized patients in Santa Catarina, Brazil

Abstract: INTRODUCTION: Carbapenems are the therapy of choice for treating severe infections caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. We aimed to assess the prevalence and antimicrobial susceptibility profiles of producers of distinct oxacillinases among nosocomial isolates of the A. calcoaceticus-A. baumannii complex in a 249-bed general hospital located in Joinville, Southern Brazil. METHODS: Of the 139 A. baumannii clinical isolates with reduced susceptibility to carbapenems between 2010 and 2013, 118 isolates from varying anatomical sites and hospital sectors were selected for genotypic analysis. Five families of genes encoding oxacillinases, namely blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, and blaOXA-143-like, wereinvestigated by multiplex polymerase chain reaction (PCR). RESULTS: Most (87.3%) isolates simultaneously carried the blaOXA-23-likeand blaOXA-51-likegenes, whereas three (2.5%) isolates harbored only blaOXA-51-likeones. The circulation of carbapenem-resistant isolates increased during the study period: from none in 2010, to 22 in 2011, 64 in 2012, and 53 in 2013. CONCLUSIONS: Isolates carrying the blaOXA-23-likeand blaOXA-51-likegenes were widely distributed in the hospital investigated. Because of the worsening scenario, the implementation of preventive measures and effective barriers is needed.

Over expression of AdeABC and AcrAB-TolC efflux systems confers tigecycline resistance in clinical isolates of Acinetobacter baumannii and Klebsiella pneumoniae

Abstract: INTRODUCTION: Due to the wide use of tigecycline in the treatment of severe infections caused by multidrug-resistant (MDR) bacteria, clinical resistance to tigecycline has increased in recent years. Here, we investigated the relationship between tigecycline resistance and the expression of efflux pumps. METHODS: Clinical isolates of Acinetobacter baumannii and Klebsiella pneumoniae were consecutively collected from hospitalized patients in three hospitals. The minimum inhibitory concentration (MIC) of tigecycline was determined using the broth microdilution method. Expression levels of efflux pump genes and regulators were examined by quantitative real-time reverse transcription polymerase chain reaction. The correlations between tigecycline MICs and gene expression levels were analyzed. RESULTS: Overall, 1,026 A. baumannii and 725 K. pneumoniae strains were collected. Most strains were isolated from sputum. The tigecycline resistance rate was 13.4% in A. baumannii isolates and 6.5% in K. pneumoniae isolates. Overexpression of AdeABC and AcrAB-TolC efflux systems was observed found in clinical tigecycline-resistant isolates. The tigecycline MIC had a linear relationship with the adeB expression level in A. baumannii isolates, but not with the acrB expression level in K. pneumoniae isolates. There were significant linear trends in the overexpression of ramA as the tigecycline MIC increased in K. pneumoniae isolates. CONCLUSIONS: Tigecycline resistance in A. baumannii and K. pneumoniae was strongly associated with the overexpression of efflux systems. More studies are needed to elucidate whether there are other regulators that affect the expression of adeB in A. baumannii and how ramA affects the expression of acrB in K. pneumoniae.

Initial Energy for External Electrical Cardioversion of Atrial Fibrillation

OBJECTIVE - To investigate the initial energy level required for electrical cardioversion of atrial fibrillation (AF). METHODS - We studied patients undergoing electrical cardioversion in the 1st Multicenter Trial of SOCESP. Patients were divided into 2 groups according to the initial energy level of electrical cardioversion: 100J and > or = 150J. We compared the efficacy of the initial and final shock of the procedure, the number of shocks administered, and the cumulative energy levels. RESULTS - Eight-six patients underwent electrical cardioversion. In 53 patients (62%), cardioversion was started with 100J, and in 33 patients (38%), cardioversion was started with > or = 150J. Groups did not differ regarding clinical features and therapeutical interventions. A tendency existed towards greater efficacy of the initial shock in patients who received > or = 150J (61% vs. 42% in the 100J group, p=0.08). The number of shocks was smaller in the > or = 150J group (1.5±0.7 vs. 2.1±1.3, p=0.04). No difference existed regarding the final efficacy of electrical cardioversion and total cumulative energy levels in both groups. In the subgroup of patients with recent-onset AF (<=48h), the cumulative energy level was lower in the 100J group (240±227J vs. 324±225J, p=0.03). CONCLUSION - Patients who were given initial energy of > or = 150J received fewer counter shocks with a tendency toward greater success than those patients who were given 100J; however, in patients with recent-onset AF, the average cumulative energy level was lower in the 100J group. These data suggest that electrical cardioversion should be initiated with energy levels > or = 150J in patients with chronic AF.

Resistance Exercise Restores Endothelial Function and Reduces Blood Pressure in Type 1 Diabetic Rats

Background: Resistance exercise effects on cardiovascular parameters are not consistent. Objectives: The effects of resistance exercise on changes in blood glucose, blood pressure and vascular reactivity were evaluated in diabetic rats. Methods: Wistar rats were divided into three groups: control group (n = 8); sedentary diabetic (n = 8); and trained diabetic (n = 8). Resistance exercise was carried out in a squat device for rats and consisted of three sets of ten repetitions with an intensity of 50%, three times per week, for eight weeks. Changes in vascular reactivity were evaluated in superior mesenteric artery rings. Results: A significant reduction in the maximum response of acetylcholine-induced relaxation was observed in the sedentary diabetic group (78.1 ± 2%) and an increase in the trained diabetic group (95 ± 3%) without changing potency. In the presence of NG-nitro-L-arginine methyl ester, the acetylcholine-induced relaxation was significantly reduced in the control and trained diabetic groups, but not in the sedentary diabetic group. Furthermore, a significant increase (p < 0.05) in mean arterial blood pressure was observed in the sedentary diabetic group (104.9 ± 5 to 126.7 ± 5 mmHg) as compared to that in the control group. However, the trained diabetic group showed a significant decrease (p < 0.05) in the mean arterial blood pressure levels (126.7 ± 5 to 105.1 ± 4 mmHg) as compared to the sedentary diabetic group. Conclusions: Resistance exercise could restore endothelial function and prevent an increase in arterial blood pressure in type 1 diabetic rats.

Resistance Training After Myocardial Infarction in Rats: Its Role on Cardiac and Autonomic Function

Background: Although resistance exercise training is part of cardiovascular rehabilitation programs, little is known about its role on the cardiac and autonomic function after myocardial infarction. Objective: To evaluate the effects of resistance exercise training, started early after myocardial infarction, on cardiac function, hemodynamic profile, and autonomic modulation in rats. Methods: Male Wistar rats were divided into four groups: sedentary control, trained control, sedentary infarcted and trained infarcted rats. Each group with n = 9 rats. The animals underwent maximum load test and echocardiography at the beginning and at the end of the resistance exercise training (in an adapted ladder, 40% to 60% of the maximum load test, 3 months, 5 days/week). At the end, hemodynamic, baroreflex sensitivity and autonomic modulation assessments were made. Results: The maximum load test increased in groups trained control (+32%) and trained infarcted (+46%) in relation to groups sedentary control and sedentary infarcted. Although no change occurred regarding the myocardial infarction size and systolic function, the E/A ratio (-23%), myocardial performance index (-39%) and systolic blood pressure (+6%) improved with resistance exercise training in group trained infarcted. Concomitantly, the training provided additional benefits in the high frequency bands of the pulse interval (+45%), as well as in the low frequency band of systolic blood pressure (-46%) in rats from group trained infarcted in relation to group sedentary infarcted. Conclusion: Resistance exercise training alone may be an important and safe tool in the management of patients after myocardial infarction, considering that it does not lead to significant changes in the ventricular function, reduces the global cardiac stress, and significantly improves the vascular and cardiac autonomic modulation in infarcted rats.

Electrical Properties of Isolated Cardiomyocytes in a Rat Model of Thiamine Deficiency

In modern society, thiamine deficiency (TD) remains an important medical condition linked to altered cardiac function. There have been contradictory reports about the impact of TD on heart physiology, especially in the context of cardiac excitability. In order to address this particular question, we used a TD rat model and patch-clamp technique to investigate the electrical properties of isolated cardiomyocytes from epicardium and endocardium. Neither cell type showed substantial differences on the action potential waveform and transient outward potassium current. Based on our results we can conclude that TD does not induce major electrical remodeling in isolated cardiac myocytes in either endocardium or epicardium cells.

Insulin Resistance, Dyslipidemia and Cardiovascular Changes in a Group of Obese Children

Introduction: Obesity-related comorbidities are present in young obese children, providing a platform for early adult cardiovascular disorders. Objectives: To compare and correlate markers of adiposity to metabolic disturbances, vascular and cardiac morphology in a European pediatric obese cohort. Methods: We carried out an observational and transversal analysis in a cohort consisting of 121 obese children of both sexes, between the ages of 6 and 17 years. The control group consisted of 40 children with normal body mass index within the same age range. Markers of adiposity, plasma lipids and lipoproteins, homeostasis model assessment-insulin resistance, common carotid artery intima-media thickness and left ventricular diameters were analyzed. Results: There were statistically significant differences between the control and obese groups for the variables analyzed, all higher in the obese group, except for age, high-density lipoprotein cholesterol and adiponectin, higher in the control group. In the obese group, body mass index was directly correlated to left ventricular mass (r=0.542; p=0.001), the homeostasis model assessment-insulin resistance (r=0.378; p=<0.001) and mean common carotid artery intima-media thickness (r=0.378; p=<0.001). In that same group, insulin resistance was present in 38.1%, 12.5% had a combined dyslipidemic pattern, and eccentric hypertrophy was the most common left ventricular geometric pattern. Conclusions: These results suggest that these markers may be used in clinical practice to stratify cardiovascular risk, as well as to assess the impact of weight control programs.

Effects of One Resistance Exercise Session on Vascular Smooth Muscle of Hypertensive Rats

AbstractBackground:Hypertension is a public health problem and increases the incidence of cardiovascular diseases.Objective:To evaluate the effects of a resistance exercise session on the contractile and relaxing mechanisms of vascular smooth muscle in mesenteric arteries of NG-nitro L-arginine methyl ester (L-NAME)-induced hypertensive rats.Methods:Wistar rats were divided into three groups: control (C), hypertensive (H), and exercised hypertensive (EH). Hypertension was induced by administration of 20 mg/kg of L-NAME for 7 days prior to experimental protocols. The resistance exercise protocol consisted of 10 sets of 10 repetitions and intensity of 40% of one repetition maximum. The reactivity of vascular smooth muscle was evaluated by concentration‑response curves to phenylephrine (PHEN), potassium chloride (KCl) and sodium nitroprusside (SNP).Results:Rats treated with L-NAME showed an increase (p < 0.001) in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) compared to the initial period of induction. No difference in PHEN sensitivity was observed between groups H and EH. Acute resistance exercise reduced (p < 0.001) the contractile response induced by KCl at concentrations of 40 and 60 mM in group EH. Greater (p < 0.01) smooth muscle sensitivity to NPS was observed in group EH as compared to group H.Conclusion:One resistance exercise session reduces the contractile response induced by KCl in addition to increasing the sensitivity of smooth muscle to NO in mesenteric arteries of hypertensive rats.