Aztreonam plus ceftazidime-avibactam as treatment of NDM-1-producing Klebsiella pneumoniae bacteraemia in a neutropenic patient: Last resort therapy?

OBJECTIVES: We report the successful treatment of a bloodstream infection caused by Klebsiella pneumoniae harbouring NDM-1 using aztreonam-ceftazidime-avibactam in a neutropenic patient in whom colistin and meropenem therapy had previously failed. METHODS: A clinical isolate was evaluated to determine the presence of NDM, TEM, SHV, CTX, and CMY, and the killing kinetics of aztreonam (ATM; 4 µg/mL), aztreonam-avibactam (ATM-AVI; 4/4 µg/mL), and colistin (2 and 4 µg/mL) were tested. RESULTS: ATM-AVI showed in vitro activity against the Klebsiella pneumoniae harbouring NDM-1, whereas colistin allowed re-growth. CONCLUSIONS: This report supports reconsideration of use of colistin for treatment of infections caused by K. pneumoniae harbouring NDM. CZA/ATM use should be kept in mind as a treatment option, perhaps earlier than colistin.

Antibacterial and cytotoxic activities of new sphingolipids and other constituents isolated from Cissus incisa leaves.

Cissus incisa is used in traditional Mexican medicine to treat certain ailments, infectious or cancerous diseases. Excepting for our previous research, this species had no scientific reports validating its traditional use. In this study, we evaluated the antibacterial and cytotoxic properties of the sphingolipids and others phytocompounds isolated from C. incisa leaves to increase the scientific knowledge of the Mexican flora. The antibacterial activity was evaluated against Gram-positive and Gram-negative bacteria by the Microdilution method. Meanwhile, the cytotoxic potential was determined on six human cancer cells: PC3, Hep3B, HepG2, MCF7, A549, and HeLa; using an aqueous solution cell proliferation assay kit. A cell line of immortalized human hepatocytes (IHH) was included as a control of non-cancerous cells. Selectivity index (SI) was determined only against the hepatocellular carcinoma cell lines. The phytochemical investigation of C. incisa leaves resulted in the isolation and characterization of five compounds: 2-(2'-hydroxydecanoyl amino)-1,3,4-hexadecanotriol-8-ene (1), 2,3-dihydroxypropyl tetracosanoate (2), ß-sitosterol-D-glucopyranoside (3), α-amyrin-3-O-ß-D-glucopyranoside (4), and a mixture of cerebrosides (5). Until now, this is the first report of the sphingolipids (1), (5-IV) and (5-V). Only the compound (4) and cerebrosides (5) exhibited antibacterial activity reaching a MIC value of 100 µg/mL against Pseudomonas aeruginosa resistant to carbapenems. While, the acetylated derivate of (3), compound (3Ac) showed the best cytotoxic result against PC3 (IC50 = 43 ± 4 µg/mL) and Hep3B (IC50 = 49.0 ± 4 µg/mL) cancer cell lines. Likewise, (3Ac) achieved better SI values on HepG2 and Hep3B cell lines. This research reveals the importance of study medicinal plants, to identify bioactive molecules as sources of potential drugs. The presence of these compounds allows us to justify the use of this plant in traditional Mexican medicine.

Metabolic Profile and Evaluation of Biological Activities of Extracts from the Stems of Cissus trifoliata.

Cissus trifoliata (L.) L belongs to the Vitaceae family and is an important medicinal plant used in Mexico for the management of infectious diseases and tumors. The present study aimed to evaluate the metabolic profile of the stems of C. trifoliata and to correlate the results with their antibacterial and cytotoxic activities. The hexane extract was analyzed using gas chromatography coupled with mass spectrometry (GC-MS) and the CHCl3-MeOH and aqueous extracts by ultraperformance liquid chromatography quadrupole time of fly mass spectrometry (UPLC-QTOF-MS). The antibacterial activity was determined by broth microdilution and the cytotoxicity was evaluated using MTS cell proliferation assay. Forty-six metabolites were putatively identified from the three extracts. Overall, terpenes, flavonoids and stilbenes characterize the metabolic profile. No antibacterial activity was found in any extract against the fifteen bacteria strains tested (MIC >500 µg/mL). However, high cytotoxic activity (IC50 ≤ 30 µg/mL) was found in the hexane and aqueous extracts against hepatocarcinoma and breast cancer cells (Hep3B, HepG2 and MCF7). This is the first report of the bioactive compounds of C. trifoliata stems and their antibacterial and cytotoxic properties. The metabolic profile rich in anticancer compounds correlate with the cytotoxic activity of the extracts from the stems of C. trifoliata. This study shows the antitumor effects of this plant used in the traditional medicine and justifies further research of its anticancer activity.

Antibacterial Activity of Cissus incisa Extracts against Multidrug- Resistant Bacteria.

AIMS: The need to find new antimicrobial agents to cope with this phenomenon increases. BACKGROUND: Infection diseases are illness caused by different microorganisms, such as bacteria, among those caused by resistant bacteria are associated with greater morbidity, mortality and cost of the treatment than those caused by sensitive bacteria of the same species. OBJECTIVE: Need to find new antimicrobial agents to cope with this phenomenon increases. METHODS: This work carried out the study of biological activities of Cissus incisa, taking account its traditional use. Three extracts were prepared from the leaves of this plant: hexane, chloroform methanol (1:1) and aqueous. Their antibacterial and antitubercular activities were evaluated using microdilution and alamar blue assays; respectively. RESULTS: The chloroform/methanol extract (1:1) was the most active of the three tested extracts for antimicrobial activity. In this way, the extract exhibits a broad spectrum of antimicrobial activity, against the Gram positive and Gram negative bacteria tested, with MIC values between 125 to 500 µg/mL. CONCLUSION: This research contributes both to the knowledge of the Mexican flora, as well as the discovery of potential antibacterial agents derivate from plants.

Hechtia glomerata Zucc: Phytochemistry and Activity of Its Extracts and Major Constituents Against Resistant Bacteria.

Hechtia glomerata Zucc. is used both as a source of food and in ethnomedicine to treat various diseases derived from bacterial infections such as bronchitis, laryngitis, nephritis, whooping cough, urethritis, and sepsis. There are no previous reports about its chemistry and biological activities. Therefore, the aims of this study were to identify components from organic and aqueous extracts of H. glomerata and test the extracts and major isolate compounds against resistant bacteria. Hexane, CHCl3/MeOH, and aqueous extracts were prepared and analyzed by different chromatographic techniques. Structural elucidation was carried out by NMR spectroscopy and X-ray diffraction. The antibacterial activities of extracts, phytochemicals, and semisynthetic derivatives against resistant bacteria were determined by the broth micro-dilution method. From the hexane extract nonacosane (1), hexatriacontanyl stearate (2), hexacosanol (3), oleic acid (4), and ß-sitosterol (5) were isolated and characterized. From the CHCl3/MeOH extract, p-coumaric acid (6), margaric acid (7), caffeic acid (8), daucosterol (9), and potassium chloride (10) were isolated and characterized. A total of 58 volatile compounds were identified by GC-MS from the hexane extract and two solids were isolated from the CHCl3/MeOH extract. The UPLC-QTOF-MS analysis of the aqueous extract allowed the identification of 55 polar compounds. Hexane and aqueous extracts showed antibacterial activity against ESBL Escherichia coli, and three strains of Klebsiella pneumoniae ESBL, NDM-1 +, and OXA-48 with MIC values of 500 µg/mL. The CHCl3/MeOH extract was devoid of activity. The activity of phytocompounds and their semisynthetic derivatives toward resistant bacteria was weak. The most active compound was ß-sitosterol acetate, with a MIC value of 100 µg/mL against carbapenem-resistant A. baumannii. This is the first report of the secondary metabolites of H. glomerata Zucc. and the activity of its extracts and major pure compounds against resistant bacterial strains.

Chemical composition of Acacia farnesiana (L) wild fruits and its activity against Mycobacterium tuberculosis and dysentery bacteria.

ETHNOPHARMACOLOGICAL RELEVANCE: In Mexico, plants are an important element of traditional medicine, and many are considered part of Mexican cultural heritage from prehispanic and colonial times. Nevertheless, relatively few systematic scientific studies have been conducted to fully characterize the chemical composition and pharmacological activities of Mexican medicinal plants. Acacia farnesiana is used in Mexican traditional medicine to treat dysentery and tuberculosis and therefore could have bioactive compounds that may explain its traditional use. AIMS OF THE STUDY: i) To isolate and characterize the compounds from the hexanic, chloroformic and methanolic extracts; ii) to identify the volatile compounds from methylated hexanic and chloroformic extracts using GC-FID and GC-MS methods; iii) to identify the compounds from methanolic and aqueous extracts using HPLC-Q-TOF-MS; iv) to test the activity of extracts and isolated compounds against Mycobacterium tuberculosis and dysentery bacteria. MATERIAL AND METHODS: A. farnesiana fruits were collected in Acatlán de Osorio, Puebla, Mexico. Hexanic, chloroformic, methanolic and aqueous extracts were prepared and analyzed by different chromatographic techniques including column chromatography, flash chromatography, GC-FID, GC-MS and HPLC-Q-TOF-MS. Structural elucidation was carried out by NMR spectroscopic analysis. The activity of extracts, phytochemicals and semi-synthetic derivatives against Mycobacterium tuberculosis H37Rv and G122 as well as dysentery bacteria (Campylobacter jejuni, Shigella flexneri, Salmonella enteritidis, Yersinia enterocolitica and enterohemorrhagic Escherichia coli) was determined by the broth microdilution method and reported as minimal inhibitory concentration (MIC µg/mL). RESULTS: From both hexane and chloroform extracts, tetracosanoic acid (2S)-2,3-dihydroxypropyl ester (1) and (3ß,22E)-estigmasta-5,22-dien-3-yl ß-D-glucopyranoside (2) were isolated and characterized. From the methanolic extract, methyl gallate (3), gallic acid (4), (3ß,22E)-estigmasta-5,22-dien-3-yl ß-D-glucopyranoside (2), (2S) naringenin 7-O-ß-glucopyranoside (prunin, 5), pinitol (6) and sucrose (7) were isolated and characterized. Furthermore, hexanic and chloroformic extracts were analyzed by GC-FID and GC-MS and 18 methylated fatty acids were identified for each extract in addition to three sterols. The methanolic and aqueous extracts were analyzed separately by HPLC-Q-TOF-MS, and 15 compounds were identified in each extract. The compounds 1, 2, and 7, in addition to 13 fatty acids and eight phenolic compounds, were identified for the first time in A. farnesiana. The extracts showed antitubercular (MIC 100-200 µg/mL) and antidysentery activity (MIC 100-200 µg/mL). Methyl gallate and its acetylated derivative showed activity against the sensible strain M. tuberculosis H37Rv with MIC values of 50-25 µg/mL, respectively. The flavanone prunin showed activity against multidrug resistant M. tuberculosis G122 (MIC 50 µg/mL). Methyl gallate, gallic acid and prunin showed activity against C. jejuni (MIC 50 µg/mL). CONCLUSIONS: The activity of tested extracts and isolated compounds against M. tuberculosis and dysentery bacteria justifies the ethnomedical use of A. farnesiana fruits for the treatment of tuberculosis and dysentery.

Chlorhexidine whole-body washing of patients reduces methicillin-resistant Staphylococcus aureus and has a direct effect on the distribution of the ST5-MRSA-II (New York/Japan) clone.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) colonizes the skin of hospitalized patients and is associated with high morbidity and mortality. To prevent colonization and infection by S. aureus, better disinfection practices are required. Therefore, we evaluated the effect of chlorhexidine whole-body washing on hospital-acquired S. aureus infections among intensive care unit (ICU) patients in a tertiary hospital in Mexico. METHODOLOGY: The study was conducted over 18 months to evaluate the effect of 2 % chlorhexidine gluconate (CXG) whole-body washing of ICU adult patients on chlorhexidine and antibiotic resistance, biofilm production and clonal distribution of S. aureus in a tertiary care hospital. Minimum inhibitory concentrations for CXG, antibiotic susceptibility and biofilm production by S. aureus isolates were determined. Pulsed-field gel electrophoresis, multilocus sequence typing (MLST) and PCR for Panton-Valentine leucocidin (PVL) were used for molecular typing of MRSA isolates.Results/Key findings. We included 158 isolates. A reduction in antibiotic resistance in the study period was observed for clindamycin, levofloxacin, norfloxacin, oxacillin and trimethoprim/sulfamethoxazole. None of the isolates showed reduced susceptibility to CXG. Most of the isolates were non-biofilm producers (147/158). The most commonly identified clone was a descendant of the ST5-MRSA-II (New York/Japan) clone. This clone decreased during the intervention period and reappeared markedly in the post-intervention period. During the post-intervention period, two isolates were related with the clone ST8-MRSA-IV (also known as USA300). CONCLUSION: Our findings suggest that the CXG bathing favored the reduction of healthcare-associated MRSA isolates and a temporary reduction of the predominant ST5-MRSA-II (New York/Japan) clone.

Influence of whole-body washing of critically ill patients with chlorhexidine on Acinetobacter baumannii isolates.

BACKGROUND: Acinetobacter baumannii is 1 of the most important nosocomial pathogens and the causative agent of numerous types of infections, especially in intensive care units (ICUs). Our aim was to evaluate the effect of 2% chlorhexidine gluconate (CHG) whole-body washing of ICU patients on A baumannii in a tertiary care hospital. METHODS: During the 6-month intervention period, 327 patients were subjected to whole-body bath with 2% CHG-impregnated wipes. blaIMP (active on imipenem), blaVIM (Verona integron-encoded metallo-ß-lactamase), and blaoxacillinase (OXA) of A baumannii were typed. Isolates were genotyped by pulsed-field gel electrophoresis. Minimum inhibitory concentrations (MIC) to CHG were determined by the agar dilution method and drug susceptibility determined using the broth microdilution method. Biofilm formation was determined by crystal violet staining. RESULTS: We analyzed 80 isolates during the baseline period and 69 isolates during the intervention period. There was a decrease in the MIC50 and MIC90 values for CHG for isolates (8 mg/L and 16 mg/L, respectively). All isolates typed positive for OXA51-like and 86% typed positive for OXA24-like pulsed-field gel electrophoresis identified 2 main clone types. During the intervention period the frequency of clone A decreased and that of clone B increased. Both clones were OXA24-like positive. CONCLUSIONS: The A baumannii isolates recovered from patients who received body washing with 2% CHG presented with a significant decrease in CHG MIC values associated with a change in clonality correlating with increased biofilm production.

Chemical composition of hexane extract of Citrus aurantifolia and anti-Mycobacterium tuberculosis activity of some of its constituents.

The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), a-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25-50 mg/mL), 1 (MICs = 50-100 mg/mL), palmitic acid (MICs = 25-50 mg/mL), linoleic acid (MICs = 50-100 mg/mL), oleic acid (MICs = 100 mg/mL), 4-hexen-3-one (MICs = 50-100 mg/mL), and citral (MICs = 50-100 mg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.

A new antimycobacterial furanolignan from Leucophyllum frutescens.

Bioassay-guided fractionation of the minor active fractions obtained from the root bark of Leucophyllumfrutescens (Berl.) I. M. Johnst. led to isolation from the n-hexane extract of a new compound with moderate activity against the H37Rv Mycobacterium tuberculosis strain (MIC 63 microg/mL), and low cytotoxicity, as shown by the IC5o against Vero cells. The compound was identified by 1D/2D NMR spectroscopy a s2',5"-dimethoxysesamin.

The bioactivity of plant extracts against representative bacterial pathogens of the lower respiratory tract.

BACKGROUND: Lower respiratory tract infections are a major cause of illness and death. Such infections are common in intensive care units (ICU) and their lethality persists despite advances in diagnosis, treatment and prevention. In Mexico, some plants are used in traditional medicine to treat respiratory diseases or ailments such as cough, bronchitis, tuberculosis and other infections. Medical knowledge derived from traditional societies has motivated searches for new bioactive molecules derived from plants that show potent activity against bacterial pathogens. Therefore, the aim of this study was to evaluate the effect of hexanic, chloroformic (CLO), methanolic (MET) and aqueous extracts from various plants used in Mexican traditional medicine on various microorganisms associated with respiratory disease. METHODS: thirty-five extracts prepared from nine plants used in Mexican traditional medicine for the treatment of respiratory infections were evaluated against 15 control bacterial species and clinical isolates. RESULTS: Both chloroformic (CLO) and methanolic (MET) extracts of Larrea tridentata were active against Methicillin-resistant S. aureus, B. subtilis and L. monocytogenes. A MET extract of L. tridentata was also active against S. aureus, S. pneumoniae, S. maltophilia, E. faecalis and H. influenzae and the CLO extract was active against A. baumannii. An Aqueous extract of M. acumitata and a MET extract of N. officinale were active against S. pneumoniae. CLO and MET extracts of L. tridentata were active against clinical isolates of S. aureus, S. pneumoniae and E. faecalis. CONCLUSION: Overall, our results support the potential use of L. tridentata as a source of antibacterial compounds.

Activity against drug resistant-tuberculosis strains of plants used in Mexican traditional medicine to treat tuberculosis and other respiratory diseases.

Tuberculosis (TB) kills about 3 million people per year worldwide. Furthermore, TB is an infectious disease associated with HIV patients, and there is a rise in multidrug-resistant TB (MDR-TB) cases around the world. There is a need for new anti-TB agents. The study evaluated the antimycobacterial activity of nine plants used in Mexican traditional medicine to treat tuberculosis and other respiratory diseases. Nasturtium officinale showed the best activity (MIC = 100 microg/mL) against the sensitive Mycobacterium tuberculosis. The following plants were active also but at 200 microg/mL: Citrus sinensis, Citrus aurantifolia, Foeniculum vulgare, Larrea tridentata, Musa acuminata and Olea europaea. Contrary to the above data, activity against drug-resistant variants of M. tuberculosis was more evident, e.g. N. officinale was the most potent (MIC < or = 100 microg/mL) against the four mono-resistant variants tested; F. vulgare and O. europaea were active against all the resistant variants (MICs < or = 100 microg/mL). The most susceptible variant was the isoniazid resistant, being inhibited by C. aurantifolia, C. sinensis and O. europaea (MIC = 25 microg/mL). These data point to the importance of biological testing of extracts against drug-resistant M. tuberculosis isolates, and the bioguided assay of these extracts for the identification of lead compounds against MDR-TB isolates.