Polymyxin B-Induced Kidney Injury Assessment of a Novel Formulation of Polymyxin B (VRP-034) in Rats.

Despite the crucial role of Polymyxin-B in treating life-threatening gram-negative infections, its clinical utility is limited due to the risk of acute kidney injury. In response, a novel formulation of polymyxin-B is being developed to mitigate drug-induced kidney injury. In this study, we have assessed the toxicity of four variants of that novel formulation (VRP034_F21-F24) in comparison with standard polymyxin-B using kidney injury biomarkers in rats. Sprague-Dawley rats were subcutaneously administered either polymyxin-B (control) or one of the four polymyxin-B formulations at a dose of 25 mg/kg/day (HED: 4 mg/kg/day) in four divided doses for two days. Serum samples were collected at baseline and at the end of day 2 for the determination of serum biomarkers. Necropsy was done on day 2 and kidney was collected for histopathological evaluation. In the control group, statistically significant increase (p < 0.0001) in all biomarkers was observed on day 2 as compared to baseline values [urea: 311%; creatinine: 700%; KIM-1: 180%; cystatin-C: 66%] and 50% of the animals died (one after the 7th dose and two after the 8th dose) before scheduled necropsy. In contrast, animals treated with novel formulations did not show a significant increase across any of the biomarkers and no mortality was observed. Histopathology of the control group kidney confirmed necrotic changes in tissues with congestion and vacuolization, whereas only minor tubular damage was noted in two formulation groups (VRP034_F21, F24) and no appreciable damage was detected in the other two groups (VRP034_F22-23). The novel formulation of polymyxin-B tested in this study significantly reduced the risk of polymyxin-induced kidney injury in rats.

CSE (Ceftriaxone+ Sulbactam+ Disodium EDTA) Versus Meropenem for the Treatment of Complicated Urinary Tract Infections, Including Acute Pyelonephritis: PLEA, a Double-Blind, Randomized Noninferiority Trial.

BACKGROUND: CSE is a novel combination of ceftriaxone, sulbactam and disodium EDTA with activity against multidrug resistant gram-negative pathogens. METHODS: Adult patients aged ≥18 years with a diagnosis of complicated urinary tract infections (cUTI), including acute pyelonephritis (AP), were randomized 1:1 to receive either intravenous CSE (1000mg ceftriaxone/500mg sulbactam/37mg disodium EDTA) every 12h or intravenous meropenem (1000mg) every 8h for up to 14 days. The primary objective was to show the noninferiority of CSE to meropenem at the test-of-cure visit (8-12 days after the end of therapy), with a noninferiority margin of 10 percent. RESULTS: Of 230 randomized patients, 74/143 and 69/143 were treated with CSE and meropenem respectively. Of these, 98% were ceftriaxone non-susceptible and 83% were ESBL-positive at baseline. Noninferiority of CSE to meropenem was demonstrated for both the US Food and Drug Administration defined co-primary endpoints of (1) symptomatic resolution at test-of-cure: 71/74 (95.9%) patients vs 62/69 (89.9%) [treatment difference, 6%; 95% CI, -2.6% to 16%] and (2) both symptomatic resolution and microbiological eradication at test-of-cure: 70/74 (94.6%) vs 60/69 (87.0%) (treatment difference, 7.6%; 95% CI, -2.0% to 18.4%). Microbiological eradication at test-of-cure (European Medical Agency's primary endpoint) was observed in 70/74 (94.6%) vs 61/69 (88.4%) [treatment difference, 6.2%; 95% CI, -3.2% to 16.6%] patients treated with CSE and meropenem respectively. Safety profile of CSE was consistent with that of ceftriaxone alone. CONCLUSIONS: The results support the use of CSE as a carbapenem-sparing treatment for patients suffering from cUTI/AP caused by resistant gram-negative pathogens. CLINICAL TRIAL REGISTRATION NUMBERS: NCT03477422; CTRI/2013/11/004133.

Molecular characterization and in vitro susceptibilities of ß-lactamase producing Escherichia coli, Klebsiella species, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus to CSE1034 and other ß-lactams.

OBJECTIVE: To study the prevalence of extended-spectrum ß-lactamases (ESBLs) among 663 clinical isolates obtained from various parts of India and to study the occurrence of different variants of ESBLs among these isolates. METHODS: Phenotypic characterization and susceptibility studies were performed according to the methods described in Clinical and Laboratory Standards Institute guidelines. The occurrence of ESBL variants was analyzed with PCR using the previously reported primers. RESULTS: Among the six hundred sixty three isolates, the identified isolates were Acinetobacter baumannii (72), Escherichia coli (218), Klebsiella pneumoniae (30), Klebsiella oxytoca (63), Pseudomonas aeruginosa (264) and Staphylococcus aureus (16). PCR results revealed that approximately 89.0% of Pseudomonas aeruginosa isolates were positive for ESBL followed by Escherichia coli (85.3%), Klebsiella pneumoniae (76.6%), Klebsiella oxytoca (73.0%), Acinetobacter baumannii (72.2%) and Staphylococcus aureus (31.2%). The overall prevalence of ESBL was 82.5%. The presence of TEM type ESBLs were the predominant (in 186 isolates), followed by SHV (138), OXA (92), CTX-M (65), AmpC (33), KPC (28) and blaZ (5). Of the drugs involved in the study, CSE1034 was found to be the most efficacious against all of ESBL positive clinical isolates showing susceptibility approximately 95.7% with minimal inhibitory concentration values between 0.125 and 8.000 µg/mL for all strains tested. The susceptibilities of penems (meropenem and imipenem and cilastatin) ranged between 83% and 93% for all the isolates. The susceptibilities of other drugs like piperacillin and tazobactam, amoxicillin and clavulanic acid, cefoperazone and sulbactam were <45% for all the isolates. CONCLUSIONS: Results of the present study indicated that majority of the isolates was susceptible to CSE1034 and it could be a potent antibacterial agent for the treatment of severe bacterial infections caused by such organisms.

Evaluation of genotoxicity of Trois through Ames and in vitro chromosomal aberration tests

Objective: To investigate the mutagenic potential of Trois using the bacterial reverse mutation assay (Ames test) and in vitro chromosomal aberration test.Methods:typhimurium (TA 98, TA100, TA1535 and TA1537) and Escherichia coli (WP2 uvrA) with and without metabolic activation system (S9 mix) at the dose range of 313 to 5000 μg/plate. Chromosomal aberrations were evaluated in Chinese hamster lung (CHL) cell line at the dose levels of 15, 7.5, 3.7, 1.9 and 0.9 mg/mL in the absence and presence of S9 mix.Results:The ability of Trois to induce reverse mutations was evaluated in Salmonella Trois used in the study with and without S9 mix in all tester strains. Trois did not produce any structural aberration in CHL cells in the presence or absence of S9 mix. There were no increases in the number of revertant colonies at any concentrations of Conclusions: Results of this study suggest that Trois is non-mutagenic.

Comparative antibacterial activity of a novel semisynthetic antibiotic: etimicin sulphate and other aminoglycosides.

Etimicin is a novel fourth generation semisynthetic aminoglycoside. It has good antimicrobial activity against both gram-positive and gram-negative bacterial infections and also against aminoglycoside resistant strains. In the present study, in vitro antibacterial activity of etimicin was determined by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time kill curve tests against type strains and 407 clinical isolates (obtained in a surveillance study), in comparison to other aminoglycosides. Test results revealed that etimicin has potential antimicrobial activity and MIC, MBC values for etimicin were low compared to other aminoglycosides. In MBC test etimicin has exhibited potential bactericidal effect ranging from 0.25 to 2 mg/L. The time kill-curve study further demonstrated the rapid, concentration dependent killing and comparative study showed etimicin to exhibit long and effective bactericidal activity over amikacin. The interesting fact is that most of the tested aminoglycoside resistant clinical isolates were susceptible to etimicin. In view of its potent in vitro antibacterial activity and efficacy profiles, it can be concluded that etimicin can be a potent injectable agent for the treatment of severe bacterial infections.

Pharmacokinetic study of sulbactomax.

We have evaluated pharmacokinetics of a fixed dose combination (FDC) of ceftriaxone and sulbactam (2:1) or sulbactomax in eight healthy volunteers. A 1.5 g dose of sulbactomax, 1 g dose of ceftriaxone and 0.5 g sulbactam were given intravenously in a balanced two-ways cross-over study. Serially collected plasma sample was analyzed for ceftriaxone and sulbactam by high performance liquid chromatography (HPLC). The mean peaks of ceftriaxone and sulbactam concentrations in plasma were 152.06+/-6.65 microg/ml and 21.32+/-1.80 microg/ml, respectively and plasma half-lives for ceftriaxone and sulbactam were 5.2+/-0.35 hr and 0.94+/-0.038 hr, respectively. The AUC0-24 for ceftriaxone and sulbactam was 760.16+/-27.68 microg.hr/ml and 20.74+/-2.34 microg.hr/ml, respectively, with elimination rate constant of 0.133+/-0.009 hr(-1) and 0.732+/-0.029 hr(-1), respectively. The kinetics of ceftriaxone and sulbactum did not change in combination as compared to the alone treatment. Also, concentration of the ceftriaxone after 24 hr is higher than the minimum inhibitory concentration (MIC) of the most of the gram positive and gram negative bacteria indicating that one dose in a day is sufficient to treat the disease caused by these organisms.

Sub-acute toxicity study of a new aminoglycoside etimicin sulphate in swiss albino mice.

Etimicin sulfate, an ethylization derivative of gentamicin, is a new soluble wide-spectrum synthetic aminoglycoside drug. It has wide antibacterial spectrum with high effect and less cross resistance as compared to other aminoglycosides. In order to further explore its safety and tolerance, we have conducted a subactute toxicity study on swiss albino mice. Results from the present study have elucidated that treatment of etimicin sulfate exerts no significant signs of toxicity at any dose level used in the study. Physiological as well as hematological parameters were unaltered throughout the study. Biochemical examination and histopathology of all organs confirmed no significant alteration at any dose levels. The result of this study has suggested there was no obvious toxicity observed with the treatment of etimicin sulphate. It was found to be a safe alternative for various severe infections.

Biochemistry of fruit softening: an overview.

Softening is a developmentally programmed ripening process, associated with biochemical changes in cell wall fractions involving hydrolytic processes resulting in breakdown of cell-wall polymers such as cellulose, hemicelluloses and pectin etc. Various hydrolytic reactions are brought about by polygalacturonase, pectin methyl esterase, pectate lyase, rhamnogalacturonase, cellulase and ß-galactosidase etc. Besides these enzymes, expansin protein also plays an important role in softening. Textural changes during ripening help in determining the shelf life of a fruit. An understanding of these changes would help in formulating procedures for controlling fruit softening vis-à-vis enhancing shelf life of fruits. In the present review an attempt has been made to coalesce recent findings on biochemistry of fruit softening.

Pathogenicity and drug resistance in Candida albicans and other yeast species. A review.

Pathogenic yeasts from the genus Candida can cause serious infection in humans particularly, in immunocompromised patients and are now recognized as major agents of hospital acquired (nosocomial) infections. In the recent years, there has been a marked increase in the incidence of treatment failures in candidiasis patients receiving long-term antifungal therapy, which has posed a serious problem in its successful use in chemotherapy. Candida cells acquire drug resistance (MDR) during the course of the treatment. The mechanisms of resistance to azole antifungal agents have been elucidated in Candida species and can be mainly categorized as (i) changes in the cell wall or plasma membrane, which lead to impaired drug (azole) uptake; (ii) alterations in the affinity of the drug target Erg11p (lanosterol 14alpha-demethylase) especially to azoles or in the cellular content of Erg11p due to target site mutation or overexpression of the ERG11 gene; and (iii) the efflux of drugs mediated by membrane transport proteins belonging to the ATP-binding cassette (ABC) transporters, namely CDR1 and CDR2 or to the major facilitator superfamily (MFS) transporter, CaMDR1. Many such manifestations are associated with the formation of Candida biofilms including those occurring on devices like indwelling intravascular catheters. Biofilm-associated Candida show uniform resistance to a wide spectrum of antifungal drugs. A combination of different resistance mechanisms is responsible for drug resistance in clinical isolates of Candida species.

Purification and characterization of pectate lyase from banana (Musa acuminata) fruits.

Pectate lyase (PEL) has been purified by hydrophobic, cation exchange and size exclusion column chromatographies from ripe banana fruit. The purified enzyme has specific activity of 680 +/- 50 pkat mg protein(-1). The molecular mass of the enzyme is 43 kDa by SDS-PAGE. The pI of the enzyme is 8 with optimum activity at pH 8.5. Analysis of the reaction products by paper and anion exchange chromatographies reveal that the enzyme releases several oligomers of unsaturated galacturonane from polygalacturonate. The K(m) values of the enzyme for polygalacturonate and citrus pectin (7.2% methylation) are 0.40 +/- 0.04 and 0.77 +/- 0.08 g l(-1), respectively. PEL is sensitive to inhibition by different phenolic compounds, thiols, reducing agents, iodoacetate and N-bromosuccinimide. The enzyme has a requirement for Ca(2+) ions. However, Mg(2+) and Mn(2+) can substitute equally well. Additive effect on the enzyme activity was observed when any two metal ions (out of Mg(2+), Ca(2+) and Mn(2+)) are present together. The banana PEL is a enzyme requiring Mg(2+), in addition to Ca(2+), for exhibiting maximum activity.

Effect of phytohormones on pectate lyase activity in ripening Musa acuminata.

A differential activity peak of pectate lyase (PEL) was observed during ripening of banana fruits (Musa acuminata Harichhal) receiving different hormone treatments. Exposure of fruits to 25 ppm ethylene for 24 h, as well as dipping of M. acuminata fruits in 1 mM 2,4-dichlorophenoxy acetic acid (2,4-D) for 4 h, hastened fruit ripening. Both PEL activity peak and climacteric peak were observed on the 4th and 10th days of treatment with ethylene and 2,4-D, respectively, compared to the 16th day in control fruits. Gibberellic acid (GA) treatment retarded fruit ripening and both PEL activity and climacteric peaks were observed on the 19th day. Treatment of fruits with ethylene or 2,4-D also advanced the appearance of a polygalacturonase (PG) peak and GA delayed its appearance, but the activity peaks always appeared in post-climacteric fruits, in contrast to PEL activity peaks coinciding with the respiratory peaks.

Pectate lyase activity during ripening of banana fruit.

Pectate lyase (PEL) activity was demonstrated in ripe banana fruits on supplementing the homogenizing medium with cysteine and Triton X-100. The enzyme was characterized on the basis of alkaline pH optimum, elimination of the activity by EDTA and activation by Ca(2+). PEL activity was not detected in preclimacteric banana fruits. PEL activity increased progressively from early climacteric and reached maximum level at climacteric peak and declined in post climacteric and over ripened fruits. Replacing pectate with pectin in PEL assay manifested enzyme activity even in preclimacteric fruits. In contrast to PEL, polygalacturonase activity progressively increased during fruit ripening even in postclimacteric fruits.