Isoniazid-N-acylhydrazones as promising compounds for the anti-tuberculosis treatment

Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis complex, still presents significant numbers of incidence and mortality, in addition to several cases of drug resistance. Resistance, especially to isoniazid, which is one of the main drugs used in the treatment, has increased. In this context, N-acylhydrazones derived from isoniazid have shown important anti-Mycobacterium tuberculosis activity. Hence, this work aimed to determine the anti-TB potential of 11 isoniazid-N-acylhydrazones (INH-acylhydrazones). For this purpose, the determination of minimum inhibitory concentration (MIC) against M. tuberculosis H37Rv and clinical isolates was carried out. Drug combination, minimum bactericidal concentration, cytotoxicity, and in silico parameters were also performed. INH-acylhydrazones (2), (8), and (9) had MIC for M. tuberculosis H37Rv similar to or lower than isoniazid, and bactericidal activity was observed. In addition, these compounds showed low cytotoxicity, with a selectivity index greater than 3,000. Interesting results were also obtained in the drug combination assay, with synergistic combinations with isoniazid, ethambutol, and rifampicin. In the in silico study, INH-acylhydrazones behaved similarly to INH, but with improvements in some aspects. Based on these findings, it is concluded that compounds (2), (8), and (9) are considered promising scaffolds and warrant further investigation for designing future antimicrobial drugs.

The chemistry of Vernonanthura nudiflora (Less.) H. Rob. flowers and its antimicrobial activities

Twenty-one known specialised metabolites were isolated from the flowers of Vernonanthura nudiflora (Less.) H. Rob., the structures of the compounds were established based on 1 D and 2 D NMR spectroscopic experiments. Others 28 compounds were putatively identified using the dereplication technique by UHPLC-HRMS/MS. Twenty-three of the compounds are being reported for the first time in this species. The mixture of sesquiterpene lactones piptocarphins A and B (17 + 18), and the flavone velutin (14) were tested against several microorganisms and showed promising activity against Mycobacterium tuberculosis with MIC of 15.6 μg/mL and 31.2 μg/mL, respectively. Furthermore, 17 + 18 showed greater cytotoxicity against VERO cells (IC₅₀ = 7.0 ± 1.73) compared to compound 14 (IC₅₀ 85.0 ± 10.6 µg/mL). These findings reveal the feasibility of using the UHPLC-ESI-HRMS/MS-based dereplication strategy in complex fractions to identify specialised metabolites, moreover to V. nudiflora flowers being a source of compounds with antimycobacterial potential.

Polymyxin B Activity Rescue by (−)-Camphene-Based Thiosemicarbazide Against Carbapenem-Resistant Enterobacterales

Due to the significant shortage of therapeutic options for carbapenem-resistant Enterobacterales (CRE) infections, new drugs or therapeutic combinations are urgently required. We show in this study that (-)-camphene-based thiosemicarbazide (TSC) may act synergistically with polymyxin B (PMB) against CRE, rescuing the activity of this antimicrobial. With the specific aim of a better molecular understanding of this effect caused by the presence of TSC, theoretical calculations were also performed in this study. Based on these findings, it is concluded that the presence of TSC moieties contributes to significant changes in the hydrogen atom charge of PMB structure, which trend more positives for the PMB/TSC system studied. This could lead to the formation of stronger hydrogen bonds in the Enterobacterales active site and, thus contribute to a molecular understanding of the PMB rescue of activity promoted by the presence of TSC moiety. As such, the clinical potential of these drug combinations requires further evaluation.

PanB over-representation as part of pyrazinamide action: a proteomic insight

Background: Pyrazinamide (PZA) represents a milestone as a first-line antituberculosis drug due to its sterilizing activity against Mycobacterium tuberculosis. Materials & Methods: The protein changes induced by subinhibitory PZA exposure of M. tuberculosis in acidic pH were evaluated by a proteomic approach. Results: Among the 1059 M. tuberculosis proteins identified, the specific acidification in the culture medium induced the over-representation of MurF (Rv2157c), and its under-representation was induced by 12 h of PZA exposure. PanB (Rv2225) was over-represented at 24 h of PZA exposure. Conclusion: The authors highlight the over-representation of PanB in M. tuberculosis correlates of PZA action in acidic pH, reinforcing the role of the pantothenate pathway as a bacillus drug target to be explored.

In Vitro and In Silico Evaluations of Anti-Mycobacterium tuberculosis Activity of Benzohydrazones Compounds

Tuberculosis is a disease caused by Mycobacterium tuberculosis, with high mortality rates and an extended treatment that causes severe adverse effects, besides the emergence of resistant bacteria. Therefore, the search for new compounds with anti-M. tuberculosis activity has considerably increased in recent years. In this context, benzohydrazones are significant compounds that have antifungal and antibacterial action. This study aimed at evaluating the in vitro activity of 18 benzohydrazones against M. tuberculosis. Compounds' cytotoxicity, inhibition of M. tuberculosis efflux pumps, and in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) assays were also performed. In general, the minimum inhibitory concentration values for the standard M. tuberculosis H₃₇Rv strain ranged from 7.8 to 250 μg/mL, and some compounds were not toxic to any of the cells tested (IC₅₀ ranged from 18.0 to 302.5 μg/mL). In addition, compounds (4) and (7) showed to be possible efflux pump inhibitors. In ADMET assays, all benzohydrazones had high gastrointestinal absorption. Most of the compounds were able to overcome the blood-brain barrier, and no compounds had irritant or tumorigenic effects. Compounds (1), (3), (9), (12), and (15) stood out for showing good activities, both in vitro and in silico assays.

Occurrence of Mycoplasma spp. and Ureaplasma spp. in genital specimens

 Mycoplasma spp. and Ureaplasma spp. belong to humans’ genitourinary microbiota and sometimes are associated with infections of the genitourinary tract. The aim of this study was to evaluate the occurrence of Mycoplasma spp. and Ureaplasma spp. in genital specimens from patients of the 15th Regional de Saúde of Paraná State, Brazil, and to correlate the results with clinical and laboratory data. A retrospective cross-sectional study was conducted, based on the analysis of results of vaginal, endocervical, urine and urethral culture for mycoplasmas from patients attended in a reference laboratory, from January 2009 to December 2016. We evaluated 2,475 results of culture for mycoplasmas. A total of 50.8% patients were positive for mycoplasmas. Of these, 76.8% had positive culture exclusively for Ureaplasma spp. and 4.7% for Mycoplasma hominis. Both microorganisms were isolated in the microbiology culture of 18.5% of patients. Among the positive culture, 81.4% had significant concentrations. Bacterial vaginosis was the most common alteration observed in association with mycoplasmas. The high positivity of cultures for mycoplasmas, especially Ureaplasma spp. found in our study, highlight the presence of these microorganisms in many of the genital tract disorders that can be sexually transmitted and, consequently, should not be neglected.

Insight about cell wall remodulation triggered by rifampicin in Mycobacterium tuberculosis

Rifampicin plays an important role during the treatment of tuberculosis, which makes it to be recommended throughout the regimen. The molecular target for rifampicin activity and resistance is the bacterial RNA polymerase coded by rpoB. However, it has been observed that Mycobacterium tuberculosis could use different metabolic pathways contributing to drug activity/resistance. In this sense, Proteomics analysis has been a key aspect towards the understanding of the dynamic genome expression triggered by drugs and other M. tuberculosis hostile stimuli. Herein, we aimed to report the changes in the M. tuberculosis protein profile triggered by rifampicin. The M. tuberculosis H₃₇Rv strain was submitted to 12, 24 and 48 h of rifampicin challenge, at the minimal inhibitory concentration (0.03 μg mL^-1), and proteins were extracted. The protein identification was carried out by liquid chromatography coupled to mass spectrometry (LC-MS). Four proteins, Ino1 (Rv0046c), FabD (Rv2243), EsxK (Rv1197) and PPE60 (Rv3478) were statistically underexpressed over 48 h of rifampicin exposure, indicating that in addition to the known activity of rifampin in transcriptional machinery in M. tuberculosis, processes related to disturbance in cell wall synthesis and lipid metabolism in the bacillus are also triggered by rifampicin contributing to bacillus death.

Minimum Bactericidal Concentration Techniques in Mycobacterium tuberculosis: A Systematic Review

Minimum bactericidal concentration (MBC) assay is an accepted parameter for evaluating new antimicrobial agents, and it is frequently used as a research tool to provide a prediction of bacterial eradication. To the best of our knowledge, there is no standardization among researchers regarding the technique used to detect a drug's MBC in Mycobacterium tuberculosis. Thus, the aim of this systematic review is to discuss the available literature in determining a drug's MBC in M. tuberculosis, to find the most commonly used technique and standardize the process. A broad and rigorous literature search of three electronic databases (PubMed, Web of Knowledge, and LILACS) was performed according to the PRISMA statement. We considered studies that were published from January 1, 1990 to February 19, 2019. Google Scholar was also searched to increase the number of publications. We searched for articles using the MeSH terms "microbiological techniques," "Mycobacterium," "antibacterial agents." In addition, free terms were used in the search. The search yielded 6,674 publications. After filter application, 5,348 publications remained. Of these, we evaluated the full text of 187 publications. By applying the inclusion criteria, 69 studies were included in the present systematic review. In the literature analyzed, a great variety in the techniques used to determine a drug's MBC in M. tuberculosis was observed. The most common variability is related to the culture media used, culture incubation time, and the percentage of bacterial death for the drug to be considered as bactericidal. The most commonly used technique for drug's MBC determination was carried out using the drug's minimum inhibitory concentration (MIC) assay. Aliquots from prior MIC values were subcultured in Middlebrook agar and incubated for 4 weeks at 35°C for determining the colony forming unit (CFU) with relevance to detect 99.9% bacilli killed or reduction in 3 log₁₀ viable bacilli.

Ginger essential oil and fractions against Mycobacterium spp

ETHNOPHARMACOLOGICAL RELEVANCE

Zingiber officinale (ginger) is a perennial herbaceous plant native in tropical Asia and generally cultivated in most American tropical countries with widespread use in popular medicine. Ginger essential oil (GEO) has been reported to exhibit several biological activities, such as antimicrobial.

AIMS OF THE STUDY

The aim of this study was to determine the composition and the property of GEO and related fractions against Mtb and NTM, as well as their cytotoxicity.

METHODS AND MATERIALS

GEO was obtained by hydrodistillation and fractionation was performed. Chemical characterization of GEO and fractions were carried out by gas chromatography/mass spectrometry. The antimycobacterial activity was evaluated by resazurin microtiter assay plate and broth microdilution method for Mtb and NTM, respectively. The cytotoxicity in Vero cells was assessed by MTT colorimetric assay.

RESULTS

The analyses showed 63 compounds in the GEO sample, characterized by a high number of monoterpenes and sesquiterpenes. GEO fractionation rendered 11 fractions (FR1 to FR11). GEO and fractions minimum inhibitory concentration ranged from 31.25 to >250 μg/mL against Mtb and from 15.6 to >250 μg/mL against NTM. GEO showed better activity against NTM, M. chelonae, and M. abscessus sub. massiliense, than the semi-pure fractions. One fraction (FR5), containing γ-eudesmol as the main compound, was the most active against Mtb and NTM. The GEO and semi-pure fractions cytotoxicity assay showed CC50 63.3 μg/mL, and 36.3-312.5 μg/mL, respectively.

CONCLUSIONS

In general, GEO showed a mix of monoterpenes and sesquiterpenes and a better antimycobacterial activity than the semi-pure fractions. Cytotoxic effects of GEO and its fractions should be better investigated.

Activity of (-)-Camphene Derivatives Against Mycobacterium tuberculosis in Acidic pH

BACKGROUND

For more than 60 years, the lack of new anti-tuberculosis drugs and the increase of resistant Mycobacterium tuberculosis lineages exhibit a therapeutic challenge, demanding new options for the treatment of resistant tuberculosis.

OBJECTIVE

Herein, we determined the (i) activities of (-)-camphene and its derivatives and (ii) combinatory effect with pyrazinamide (PZA) against Mycobacterium tuberculosis in acidic pH and (iii) cytotoxicity on VERO cells.

METHODS

The activity of (-)-camphene and its 15 derivatives was determined in M. tuberculosis H37Rv in culture medium at pH 6.0 by Resazurin Microtiter Assay Plate (REMA). The activity and combinatory study of three (-)-camphene derivatives with PZA was carried out on seven multidrugresistant (MDR) clinical isolates by REMA and Checkerboard, respectively. The assay of 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) bromide in VERO cells was used to determine the derivatives' cytotoxicity.

RESULTS

Four (-)-camphene derivatives, (4), (5a) (5d) and (5h), showed a reduction in the MIC value at pH 6.0 compared to the MIC detected at pH 6.8 in M. tuberculosis H₃₇Rv and multidrug resistant clinical isolates. Three (-)-camphene derivatives, (4), (5d) and (5h), showed synergistic effect (FICI ≤ 0.5) combined with PZA and were more selective for M. tuberculosis than VERO cell (selective index from 7.7 to 84.2).

CONCLUSION

Three (-)-camphene derivatives have shown to be promising anti-TB molecule scaffolds due to their low MIC values in acidic pH against MDR M. tuberculosis clinical isolates, synergism with PZA and low cytotoxicity.

Promising Antituberculosis Activity of Piperine Combined with Antimicrobials: A Systematic Review

Piperine, a bioactive compound from Piper nigrum and Piper longum, has shown promising activity as efflux pump (EP) inhibitor and as adjunct in treatment of tuberculosis (TB). The present systematic review investigated scientific studies of the activity of piperine against mycobacteria, with a focus on its mechanism of action, drug interactions, and antimycobacterial activity. A broad and rigorous literature search of three electronic databases (PubMed, Web of Knowledge, and LILACS) was performed according to the PRISMA statement. We considered studies that were published up to December 1, 2017. Google Scholar was also searched to increase the number of publications. We searched for articles using the search terms "piperine" and "Mycobacterium spp." The search yielded a total of 225 articles. After removing duplicate publications, 208 publications remained. Of these, we evaluated the full text of 13 articles. After applying the inclusion criteria, eight studies were included in the present systematic review. The results of the systematic review showed that piperine has promising anti-TB activity, mainly when combined with antimicrobials, and plays an important role as an EP inhibitor.

Anti-Mycobacterium tuberculosis activity of essential oil and 6,7-dehydroroyleanone isolated from leaves of Tetradenia riparia (Hochst.) Codd (Lamiaceae)

BACKGROUND

The global resurgence of tuberculosis (TB) and the development of drug resistance, as multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis isolates, are a threat to TB control and have created a need for new and more effective anti-TB drugs.

AIM

The current study evaluated the in vitro cytotoxicity and activity of Tetradenia riparia essential oil (TrEO) and 6,7-dehydroroyleanone pure compound against M. tuberculosis H₃₇Rv and susceptible and resistant clinical isolates.

METHODS

The in vitro activities of TrEO and 6,7-dehydroroyleanone were determined by Resazurin Microtiter Assay Plate (REMA). The cytotoxicity was evaluated in murine peritoneal macrophages by Alamar Blue assay. The cytotoxic effects were expressed as median concentration cytotoxicity (CC₅₀) and the selectivity index (SI) was calculated.

RESULTS

TrEO and 6,7-dehydroroyleanone showed activity against M. tuberculosis H₃₇Rv with minimum inhibitory concentration (MIC) 62.5 µg/ml and 31.2 µg/ml, respectively. Both of them exhibited activities against resistant and susceptible M. tuberculosis clinical isolates with MIC values between 31.2 and 62.5 µg/ml. Cytotoxicity assays showed SI 1.9 and 7.9 for TrEO and 6,7-dehydroroyleanone, respectively.

CONCLUSION

These results revealed that TrEO isolated from leaves of T. riparia and the pure compound 6,7-dehydroroyleanone display good activity against M. tuberculosis clinical isolates, including MDR isolates, with low cytotoxicity to murine macrophages. The 6,7-dehydroroyleanone compound is a potential candidate for anti-TB drug.

RDRioMycobacterium tuberculosis lineage in the Brazil/Paraguay/Argentina triple border

The high tuberculosis (TB) incidence rates, the closeness of the cities and the high migration flux on the Brazil/Paraguay/Argentina border deserves an in-depth study, using Mycobacterial Interspersed Repetitive Unit (MIRU) and Spoligotyping genetic markers to explore the impact of the Mycobacterium tuberculosis RD^Rio lineage on disease transmission and resistance to anti-TB drugs in this setting. Although without the totality of M. tuberculosis isolates causing TB in this studied setting, a number of 97 isolates obtained from sputa samples culture of patients with confirmed TB, from 2013 to 2015, were submitted to 24 loci MIRU, Spoligotyping, detection of RD^Rio lineage and detection of mutation related to isoniazid and rifampicin resistance by MTBDRplus/DNA STRIP. In this sample, it was observed high clonal variability of circulating M. tuberculosis isolates causing TB in Brazilian cities bordering Paraguay and Argentina. The percentage of RD^Rio lineage causing TB in this setting was 15.46%, and lower than the detected in different areas of Brazil. According to 24 loci MIRU, the major MIRU International Type (MIT) related with RD^Rio lineage were MIT 26, MIT 738, MIT 601 with four, two and one isolates, respectively. Eight isolates with RD^Rio marker were classified as orphans. The mainly Spoligofamily related with RD^Rio lineage was LAM1 and LAM9 and no relationship between RD^Rio lineage and resistance in M. tuberculosis isolates circulating in this setting could be established. This work is pioneer in studying the dynamics of RD^Rio lineage transmission on the Brazil/Paraguay/Argentina border and deserves further studies to analyze the real contribution of the RD^Rio lineage in outbreaks and the risk of significant development of MDR-TB in the setting studied.

In vitro interaction of eupomatenoid-5 from Piper solmsianum C. DC. var. solmsianum and anti-tuberculosis drugs

SETTING

Department of Clinical Analysis and Biomedicine, State University of Maringa, Maringa, Parana, Brazil.

OBJECTIVE

To evaluate the in vitro interaction between eupomatenoid-5 (EUP-5), extracted from Piper solmsianum C. DC. var. solmsianum, and first-line anti-tuberculosis drugs against Mycobacterium tuberculosis H₃₇Rv and 20 clinical isolates.

DESIGN

Resazurin drugs combination microtiter assay (REDCA) was performed to determine the interaction between EUP-5 and isoniazid, rifampicin (RMP) and ethambutol (EMB).

RESULTS

Synergism was observed in M. tuberculosis H₃₇Rv and eight clinical isolates with EUP-5+RMP, and in M. tuberculosis H₃₇Rv and 17 clinical isolates with EUP-5+EMB combinations.

CONCLUSION

EUP-5 is a promising compound for further studies on the development of anti-tuberculosis drugs.

Multiplex-PCR for differentiation of Mycobacterium bovis from Mycobacterium tuberculosis complex

We evaluated a multiplex-PCR to differentiate Mycobacterium bovis from M. tuberculosis Complex (MTC) by one step amplification based on simultaneous detection of pncA 169C > G change in M. bovis and the IS6110 present in MTC species. Our findings showed the proposed multiplex-PCR is a very useful tool for complementation in differentiating M. bovis from other cultured MTC species.

Occurrence of Mycobacterium bovis and non-tuberculous mycobacteria (NTM) in raw and pasteurized milk in the northwestern region of Paraná, Brazil

Milk is widely consumed in Brazil and can be the vehicle of agent transmission. In this study, was evaluated the occurrence of Mycobacterium bovis and non-tuberculous mycobacteria (NTM) in raw and pasteurized milk consumed in the northwestern region of Paraná, Brazil. Fifty-two milk samples (20 pasteurized and 32 raw) from dairy farms near the municipality of Maringa, Parana State, Brazil were collected. Milk samples were decontaminated using 5% oxalic acid method and cultured on Lowenstein-Jensen and Stonebrink media at 35 °C and 30 °C, with and without 5–10% CO₂. Mycobacteria isolates were identified by morphological features, PCR-Restriction Fragment Length Polymorphism Analysis (PCR-PRA) and Mycolic acids analysis. Thirteen (25%) raw and 2 (4%) pasteurized milk samples were positive for acid fast bacilli growth. Nine different species of NTM were isolated (M. nonchromogenicum, M. peregrinum, M. smegmatis, M. neoaurum, M. fortuitum, M. chelonae, M. flavescens, M. kansasii and M. scrofulaceum). M. bovis was not detected. Raw and pasteurized milk may be considered one source for NTM human infection. The paper reinforces the need for intensification of measures in order to avoid the milk contamination and consequently prevent diseases in the south of Brazil.

Anti-Mycobacterium tuberculosis activity and cytotoxicity of Calophyllum brasiliense Cambess (Clusiaceae)

We evaluated the in vitro anti-Mycobacterium tuberculosis activity and the cytotoxicity of dichloromethane extract and pure compounds from the leaves of Calophyllum brasiliense. Purification of the dichloromethane extract yielded the pure compounds (-) mammea A/BB (1), (-) mammea B/BB (2) and amentoflavone (3). The compound structures were elucidated on the basis of spectroscopic and spectrometric data. The contents of bioactive compounds in the extracts were quantified using high performance liquid chromatography coupled to an ultraviolet detector. The anti-M. tuberculosis activity of the extracts and the pure compounds was evaluated using a resazurin microtitre assay plate. The cytotoxicity assay was performed in J774G.8 macrophages using the 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colourimetric method. The quantification of the dichloromethane extract showed (1) and (2) at concentrations of 31.86 ± 2.6 and 8.24 ± 1.1 µg/mg of extract, respectively. The dichloromethane and aqueous extracts showed anti-M. tuberculosis H37Rv activity of 62.5 and 125 µg/mL, respectively. Coumarins (1) and (2) showed minimal inhibitory concentration ranges of 31.2 and 62.5 µg/mL against M. tuberculosis H37Rv and clinical isolates. Compound (3) showed no activity against M. tuberculosis H37Rv. The selectivity index ranged from 0.59-1.06. We report the activity of the extracts and coumarins from the leaves of C. brasiliense against M. tuberculosis.

Anti-tuberculosis neolignans from Piper regnellii

The present study determined the anti-Mycobacterium tuberculosis activities of supercritical CO2 extracts, neolignans eupomatenoid-5 (1), conocarpan (4) and eupomatenoid-3 (7) and their derivatives (2, 3, 5, 6, and 8) from Piper regnellii, as well as their cytotoxicities. The supercritical CO2 extract from leaves was purified by chromatographic methods, yielding compounds (1), (4) and (7), which were identified by (1)H NMR and comparison with literature data. Anti-M. tuberculosis activity (H37Rv and clinical isolates) was evaluated using a resazurin microtiter assay plate (REMA) to determine the MIC. The cytotoxicity assay was carried out in macrophages J774G.8 by sulforhodamine B colorimetric assay. The supercritical CO2 extracts from leaves and stems, and compound (4) showed activity against M. tuberculosis (MIC 15.6 μg/ml). Compound (1) showed the best activity (MIC 1.9 μg/ml), with good SI. Compounds (7) and (8) showed low activity against M. tuberculosis H37Rv. The derivative compounds did not show increased anti-M. tuberculosis activity. This is the first report, to our knowledge, to describe neolignans from P. regnellii with activity against M. tuberculosis, and compound (1) is a potential candidate for future antituberculosis drugs.

Use of the polymerase chain reaction to detect Mycobacterium leprae in urine

Leprosy is an infectious disease caused by Mycobacterium leprae. The polymerase chain reaction (PCR) has been applied to detect M. leprae in different clinical samples and urine seems to be attractive for this purpose. PCR was used to improve the sensitivity for diagnosing leprosy by amplifying a 151-bp PCR fragment of the M. leprae pra gene (PCR-Pra) in urine samples. Seventy-three leprosy patients (39 males and 34 females, 14 to 78 years old) were selected for leprosy diagnosis at a reference laboratory in Maringá, PR, Brazil. Of these, 36 were under anti-leprosy multidrug therapy with dapsone and rifampicin for tuberculoid (TT) and dapsone, rifampicin and clofazimine for borderline (BB) and lepromatous (LL) forms. The control group contained 50 healthy individuals without any clinical history of leprosy. DNA isolated from leprosy patients' urine samples was successfully amplified by PCR-Pra in 46.6% (34/73) of the cases. The positivity of PCR-Pra for patients with the TT form was 75% for both patients under treatment and non-treated patients (P = 0.1306). In patients with the LL form, PCR-Pra positivity was 52 and 30% for patients under treatment and non-treated patients, respectively (P = 0.2386). PCR-Pra showed a statistically significant difference in detecting M. leprae between the TT and LL forms of leprosy in patients under treatment (P = 0.0033). Although the current study showed that the proposed PCR-Pra has some limitations in the detection of M. leprae, this method has the potential to be a useful tool for leprosy diagnosis mainly in TT leprosy where the AFB slit-skin smear is always negative.

Occurrence and antibiotic resistance of coliform bacteria and antimicrobial residues in pasteurized cow's milk from Brazil

In this study we examined the hygienic and sanitary quality of pasteurized cow's milk in the state of Paraná, Brazil, by determining the presence of coliforms and occurrence of antimicrobial residues. A total of 260 milk samples were collected from commercial establishments in different regions of the state. Coliform populations were estimated by the multiple-tube test, and antimicrobial residues were detected by enzyme-linked immunosorbent assay. Overall, 105 samples (40.4%) were unsuitable for consumption according to Brazilian legal standards. Among the coliforms, Escherichia coli and Klebsiella pneumoniae were respectively identified in 77.05 and 36.07% of the samples. The highest rates of resistance to antimicrobial agents were observed for ampicillin (19.2%), cephalothin (18.9%), and tetracycline (17.1%). Antimicrobial residues were detected in 80 samples (30.8%). Forty-eight samples (18.5%) were positive for tetracycline, 29 (17.4%) for neomycin, 9 (3.5%) for beta-lactams, 6 (2.3%) for gentamicin, 4 (1.5%) for chloramphenicol, and 1 (0.4%) for streptomycin-dihydrostreptomycin. The results demonstrate a high prevalence of coliforms and also a high occurrence of antimicrobial residues in pasteurized cow's milk from Paraná, Brazil.

Direct detection of Mycobacterium bovis in bovine lymph nodes by PCR

Thirty-five lymph node samples were taken from animals with macroscopic lesions consistent with Mycobacterium bovis infection. The animals were identified by postmortem examination in an abattoir in the northwestern region of state of Paraná, Brazil. Twenty-two of the animals had previously been found to be tuberculin skin test positive. Tissue samples were decontaminated by Petroff's method and processed for acid-fast bacilli staining, culture in Stonebrink and Lowenstein-Jensen media and DNA extraction. Lymph node DNA samples were amplified by PCR in the absence and presence (inhibitor controls) of DNA extracted from M. bovis culture. Mycobacterium bovis was identified in 14 (42.4%) lymph node samples by both PCR and by culture. The frequency of PCR-positive results (54.5%) was similar to that of culture-positive results (51.5%, P > 0.05). The percentage of PCR-positive lymph nodes increased from 39.4% (13/33) to 54.5% (18/33) when samples that were initially PCR-negative were reanalysed using 2.5 microl DNA (two samples) and 1 : 2 diluted DNA (three samples). PCR sensitivity was affected by inhibitors and by the amount of DNA in the clinical samples. Our results indicate that direct detection of M. bovis in lymph nodes by PCR may be a fast and useful tool for bovine tuberculosis epidemic management in the region.

Comparative effect of physiological levels of leptin and insulin on cyclic AMP-induced stimulation of hepatic glycogen breakdown

Physiological level of insulin showed more prominent inhibiting effect on the activation of hepatic glucose production and glycogenolysis promoted by cAMP than physiological levels of leptin.