Drug Repurposing for Candidate SARS-CoV-2 Main Protease Inhibitors by a Novel In Silico Method.

The SARS-CoV-2 outbreak caused an unprecedented global public health threat, having a high transmission rate with currently no drugs or vaccines approved. An alternative powerful additional approach to counteract COVID-19 is in silico drug repurposing. The SARS-CoV-2 main protease is essential for viral replication and an attractive drug target. In this study, we used the virtual screening protocol with both long-range and short-range interactions to select candidate SARS-CoV-2 main protease inhibitors. First, the Informational spectrum method applied for small molecules was used for searching the Drugbank database and further followed by molecular docking. After in silico screening of drug space, we identified 57 drugs as potential SARS-CoV-2 main protease inhibitors that we propose for further experimental testing.

Interference of new penicillins and cephalosporins with urine glucose monitoring tests.

The possibility that three new penicillins (mezlocillin, pipericillin, and azlocillin) and two new cephalosporins (ceftazidime and cefoperazone) might give false positive urine glucose testing results was studied. High and low concentrations of antibiotics were dissolved in urine and tested with Clinitest (Ames Division, Miles Laboratories, Elkhart, Indiana) and Tes-Tape (Eli Lilly and Company, Indianapolis, Indiana) at four different concentrations of glucose. None of the antibiotics interfered with the accuracy of Tes-Tape readings. All antibiotics interfered with Clinitest readings; the greatest interference was noted at high concentrations of antibiotics and low concentrations of glucose, and with the two cephalosporins. A summary of all reported cephalosporin interactions with Clinitest urine glucose testing is included.

Clinical determinants for the recovery of fungal and mezlocillin-resistant pathogens from bile specimens.

We conducted a retrospective analysis of all bile specimens obtained for routine cultures from January 1995 through December 1999 at our tertiary care hospital. Results of microbiologic testing were linked to clinical parameters gathered by means of chart review. A total of 722 isolates were cultured from 345 of 454 bile specimens obtained from 288 individual patients. Prior receipt of a >7-day course of antibiotics (odds ratio [OR], 5.7), extensive leukocytosis (leukocyte count, >20,000 cells/microL) on admission (OR, 7.8), endoscopic or percutaneous biliary manipulation during the previous 14 days (OR, 2.9), and treatment in an internal medicine ward (OR, 2.5) were independent factors significantly associated (Pless-than-or-eq, slant.05) with recovery of Candida species from bile specimens. Culture of mezlocillin-resistant bacteria from bile specimens was independently associated with the specimen having been obtained >1 week after admission (OR, 3.8), lack of history of endoscopic biliary drainage (OR, 3.2), and high serum aspartate aminotransferase levels (>72 U/L) on admission (OR, 2.6). Prospective studies are warranted to evaluate accordingly adjusted empiric therapies for biliary infections.

Influence of coadministration on the pharmacokinetics of mezlocillin and cefotaxime in healthy volunteers and in patients with renal failure.

The pharmacokinetic disposition of cefotaxime, desacetyl cefotaxime, and mezlocillin after the administration of each drug singly and in combination was examined in eight healthy volunteers and in five anuric patients with end-stage renal disease (ESRD). In the presence of ESRD, the total body clearance of cefotaxime decreased from 256.7 +/- 41.5 to 65.4 +/- 42.0 ml/min, and its elimination half-life (t1/2) increased from 1.1 to 3.6 hours as compared with healthy volunteers. Concomitant administration of mezlocillin in healthy volunteers decreased the total body clearance of cefotaxime by 42% and increased its steady-state volume of distribution. This reduction in clearance was reflected by a decrease in both renal and nonrenal clearances. In the presence of ESRD, coadministration of mezlocillin increased the t1/2 of cefotaxime to 5.8 hours. Desacetyl cefotaxime accumulated in ESRD with a prolongation of its elimination t1/2 to 18.7 hours from 1.7 hours in healthy volunteers. Desacetyl cefotaxime peak plasma concentrations occurred later with the combination regimen in the presence of ESRD. The clearance of mezlocillin was reduced and t1/2 prolonged in ESRD from 194.6 +/- 31.9 to 76.4 +/- 38.8 ml/min and 1.4 to 2.3 hours, respectively. Concomitant administration of cefotaxime did not alter the pharmacokinetics of mezlocillin. These data suggest that in the presence of normal renal function, lower doses of cefotaxime may be adequate to maintain similar cefotaxime plasma concentrations when mezlocillin is coadministered compared to when cefotaxime is given alone. Additional pharmacodynamic and clinical studies with this combination are warranted to further elucidate the clinical impact of this pharmacokinetic interaction.

Aztreonam susceptibility testing. A retrospective analysis.

Aztreonam is a structurally and immunologically unique beta-lactam antibiotic with activity exclusively against aerobic gram-negative micro-organisms. Between 1983 and 1988, its antimicrobial spectrum was evaluated against more than 5,800 fresh clinical isolates at a 300-bed community teaching hospital. Only 1.1 percent of Enterobacteriaceae isolates were resistant to aztreonam over the five-year study period, an incidence similar to that observed with aminoglycoside antibiotics. Aztreonam was found to be more active than third-generation cephalosporins and comparable with mezlocillin against Enterobacter spp., Morganella, and Citrobacter freundii. Although aztreonam was somewhat less active against nonfermenting gram-negative bacilli, such as Pseudomonas and Acinetobacter, overall more than 90 percent of Pseudomonas aeruginosa isolates were susceptible. Ceftazidime was the most active beta-lactam tested against nonfermenters. Against aerobic gram-positive cocci, aztreonam possessed no clinically useful activity. No significant change in susceptibility to aztreonam was observed over the five-year study period for Enterobacteriaceae. For third-generation cephalosporins, however, a trend toward increased resistance was noted, particularly for Enterobacter spp. and C. freundii. A 50 percent increase in resistance to aztreonam was observed over the five-year study period for nonfermenters, particularly P. aeruginosa and Acinetobacter anitratus. Similar increases in resistance were seen with other beta-lactams and gentamicin. Based on its potent in vitro activity, aztreonam appears to be a useful agent and a desirable alternative to aminoglycoside antibiotics for the treatment of pure aerobic gram-negative bacillary infections, or as a component in combination therapy against mixed infections.

Cefoperazone plus mezlocillin for empiric therapy of febrile cancer patients.

Two dosing regimens of cefoperazone plus mezlocillin were compared in a prospective, randomized trial for therapy of febrile cancer patients. The two regimens were 5 g mezlocillin plus 2 g cefoperazone intravenously every four hours (higher dose) or 3 g mezlocillin plus 1 g cefoperazone intravenously every four hours (lower dose). Although the overall response rate was higher with the higher dose regimen (78 percent versus 66 percent, p = 0.04), the two regimens were comparable in patients with documented infections (72 percent versus 68 percent). Likewise, the two regimens were equally effective against those infections in which the pathogen could be determined (82 percent versus 82 percent). Serum bactericidal titers of at least 1:32 against a known pathogen were associated with a higher response rate than were titers of less than 1:32, but the higher dose regimen did not result in higher serum bactericidal titers. Hypoprothrombinemia was a side effect, especially with the higher dose regimen, before prophylactic vitamin K was routinely administered to patients. Since there were no major benefits with the use of the higher dose regimen of mezlocillin plus cefoperazone, the lower dose regimen is more appropriate for routine usage.

Beta-lactam antibiotics inhibit agonist-stimulated platelet calcium influx.

beta-lactam antibiotics cause platelet dysfunction with reversible agonist-receptor inhibition, irreversible [14C]-penicillin binding, and inhibition of agonist-stimulated elevation in cytosolic Ca2+ ([Ca2+]i), occurring after 24 h exposure in vitro and after in vivo treatment. We investigated beta-lactam antibiotic-induced inhibition of rises in [Ca2+]i stimulated by thrombin, sodium arachidonate or A23187 to determine whether Ca2+ influx or intracellular release was primarily affected. The mean rise in [Ca2+]i, measured with fura-2-AM, was inhibited 43.7-84.1% by penicillin when the extracellular Ca2+ concentration ([Ca2+]e) was 1 mM, but was significantly less inhibited when [Ca2+]e was < 1 microM. NiCl2 (2 mM), that blocks Ca2+ influx, caused inhibition comparable to penicillin. MnCl2 (1 mM), that quenches the intracellular fura-2 signal, significantly decreased the rise in 1 mM [Ca2+]i when [Ca2+]e was 1 mM, but did not increase the inhibition caused by penicillin. Penicillin did not inhibit the rise in [Ca2+]i stimulated by inositol-1,4,5-trisphosphate or GTP gamma S. Therefore, beta-lactam antibiotics inhibit agonist-induced elevations of [Ca2+]i primarily through inhibition of Ca2+ influx, which probably accounts for the irreversible inhibition of platelet function seen after prolonged in vitro or in vivo treatment.

Bacteriostatic and bactericidal activity of penicillins at constant and variable concentrations.

Temocillin, the first beta-lactamase stable penicillin which is active against Gram-negative bacteria, was shown to be much more potent than ampicillin, piperacillin and mezlocillin against most species of Enterobacteriaceae. All isolates of Escherichia coli producing TEM 1, TEM 2 or OXA 1 beta-lactamases were sensitive to temocillin. When the prolonged kinetics of elimination of temocillin were simulated in an in vitro system, more rapid killing and less regrowth occurred as compared with penicillins with more rapid elimination.

A survey of temocillin sensitivity of strains resistant to newer beta-lactam antibiotics.

The susceptibility of a total of 2014 Gram-negative clinical isolates (except Pseudomonas aeruginosa) to a number of antibiotics, including temocillin, was investigated in 2 geographically distinct areas. Overall, more strains were sensitive to temocillin than to mezlocillin, piperacillin, amoxycillin plus clavulanic acid, cefotaxime, cephazolin, latamoxef (moxalactam), cefoxitin, or netilmicin. Susceptibility to temocillin of multiple-resistant strains was studied.

Antibacterial activity of temocillin.

The in vitro antibacterial activity of temocillin, a new penicillin, was determined in quantitative broth dilution tests, and compared with that of mezlocillin, piperacillin, cephazolin and cefotaxime. 805 clinical isolates of the Enterobacteriaceae family were tested, with temocillin exhibiting a high level of antibacterial activity against the various bacterial species, including mezlocillin-resistant strains. With the exception of Serratia marcescens, the minimum inhibitory concentrations (MICs) of 90% of tested strains of various species were in the range of 1 to 8 mg/L temocillin. Concentrations of 16 mg/L were required to inhibit 80% of S. marcescens strains, and some isolates were resistant. Significant differences between the MIC and MBC values were not observed. Furthermore, the pharmacokinetics of the bactericidal action of temocillin against mezlocillin-resistant strains was investigated, and killing curves showed that the compound was bactericidal at the MIC and the MBC.

In vitro comparison of mezlocillin and piperacillin plus tobramycin or gentamicin versus 100 gram-negative nosocomial bloodstream isolates.

We compared the in vitro activity of mezlocillin and piperacillin, alone and in combination with tobramycin or gentamicin, against clinical isolates of gram-negative bacilli from hospitalized patients with 100 distinct episodes of nosocomial bacteremia. The minimum inhibitory concentrations (MICs) necessary to inhibit 50% and 90% of isolates showed that piperacillin was most active against Pseudomonas aeruginosa. The MIC needed to inhibit 90% of isolates also showed that mezlocillin was more active against Enterobacter cloacae. Activities of the two acylaminopenicillins were comparable against the rest of the isolates. Combining the acylaminopenicillins with either gentamicin or tobramycin decreased the MICs fourfold or more for both combinations. Synergy occurred more frequently with mezlocillin-gentamicin (12%), followed by piperacillin-tobramycin (9%), mezlocillin-tobramycin (6%), and piperacillin-gentamicin (5%). Antagonism for Enterobacteriaceae isolates was observed most frequently with the combination of piperacillin plus tobramycin (20%), followed by mezlocillin plus tobramycin (17.6%), piperacillin plus gentamicin (12.9%), and mezlocillin plus gentamicin (8.2%). There are very few differences in the activities of mezlocillin and piperacillin combined with either gentamicin or tobramycin versus nosocomial gram-negative bloodstream isolates.

Evaluation of 500 gram negative isolates to determine the number of major susceptibility interpretation discrepancies between the Vitek and MicroScan Walkaway for 9 antimicrobial agents.

Although the Vitek and MicroScan Walkaway are two of the most commonly used automated antimicrobial susceptibility test systems, few studies have been performed comparing discrepancies between these systems. In this study, 500 Gram negative clinical isolates were tested against ampicillin, ampicillin/sulbactam, ticarcillin, ticarcillin/clavulanate, imipenem, ciprofloxacin, norfloxacin, mezlocillin, and piperacillin to determine the number of major interpretation discrepancies between the two systems. The 500 isolates consisted of 100 isolates each of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Enterobacter species. Each isolate was tested simultaneously in both systems using the same standardized inoculum. Eighty-four major discrepancies occurred, of which 48 were reproducible. The reproducible discrepancy rate, for the 4,500 isolate/antimicrobic combinations tested, was 48 of 4500 (1.06%). The rate for individual antimicrobics varied from 17 of 500 (3.4%) for ampicillin to no discrepancies for ticarcillin or ciprofloxacin. Of the 48 reproducible discrepancies, 44 (92%) were Vitek resistant, MicroScan susceptible. Fifteen (31%) of the Vitek and 21 (44%) of the MicroScan results were confirmed by broth microdilution. Disk diffusion results were in agreement with 15 (31%) of the Vitek and 21 (44%) of the MicroScan results. Twelve (25%) of the broth microdilution and 12 (25%) of the disk diffusion results were intermediate. The broth microdilution and disk diffusion results for the 48 isolates with reproducible discrepancies were in agreement more often with MicroScan. However, there was less very major error comparing the Vitek results for these isolates to the broth microdilution and disk diffusion. Overall, the result of this evaluation indicate that the number of major interpretation discrepancies between the two systems is minimal for the isolate/antimicrobic combinations tested.

Use of pharmacodynamic concepts in developing a cost-effective dosing method for piperacillin.

Because they were almost always used in combination with an aminoglycoside, piperacillin and mezlocillin were considered therapeutic alternatives at Hartford Hospital, a 900-bed teaching facility. To determine an appropriate comparative dose, the bactericidal activities of 5 gm of mezlocillin and 4 gm and 3 gm of piperacillin were compared. The results demonstrated that 4 gm of piperacillin possessed stronger bactericidal activity than either 3 gm of piperacillin or 5 gm of mezlocillin. Hartford Hospital has since approved an antibiotic management program using 4 gm of piperacillin every 8 hours, thereby reducing the daily cost of antibiotic therapy. The modified program offers the hospital measurable cost savings without jeopardizing the quality of care.

In vitro activity of piperacillin, ticarcillin, mezlocillin, ticarcillin-clavulanic acid, aztreonam, ceftazidime, azlocillin, cefoperazone, and thienamycin against Pseudomonas aeruginosa.

The in vitro susceptibility of 103 well-characterized strains of Pseudomonas aeruginosa to nine antimicrobial agents was assessed by means of the Kirby-Bauer disk diffusion assay and the microtiter minimal inhibitory concentration assay. The antimicrobials, from the most to the least active against P aeruginosa, were thienamycin greater than ceftazidime greater than piperacillin greater than azlocillin greater than cefoperazone greater than aztreonam greater than ticarcillin greater than ticarcillin-clavulanic acid greater than mezlocillin. The resistance patterns of the antimicrobial agents suggest that P aeruginosa resistant to a penicillin, cephalosporin, or aztreonam may be susceptible to thienamycin.

In vitro activity of mezlocillin, meropenem, aztreonam, vancomycin, teicoplanin, ribostamycin and fusidic acid against Borrelia burgdorferi.

The in vitro susceptibility profile of Borrelia burgdorferi is not yet well defined for several antibiotics. Our study explored the in vitro susceptibility of B. burgdorferi to mezlocillin, meropenem, aztreonam, vancomycin, teicoplanin, ribostamycin and fusidic acid. Minimal inhibitory concentrations (MICs) and minimal borreliacidal concentrations (MBCs) were measured using a standardised colorimetric microdilution method and conventional subculture experiments. MIC values were lowest for mezlocillin (MIC(90), < or =0.06 mg/l) and meropenem (MIC(90), 0.33 mg/l). Vancomycin (MIC(90), 0.83 mg/l) was less effective in vitro. Borreliae proved to be resistant to aztreonam (MIC(90), >32 mg/l), teicoplanin (MIC(90), 6.6 mg/l), ribostamycin (MIC(90), 32 mg/l), and fusidic acid (MIC(90), >4 mg/l). The mean MBCs resulting in 100% killing of the final inoculum after 72 h of incubation were lowest for mezlocillin (MBC, 0.83 mg/l). This study gathered further data on the in vitro susceptibility patterns of the B. burgdorferi complex. The excellent in vitro effectiveness of acylamino-penicillin derivatives and their suitability for the therapy of Lyme disease is emphasised.

Comparative in vitro activity of ticarcillin, piperacillin, azlocillin and mezlocillin.

The in vitro activity of ticarcillin, piperacillin, azlocillin and mezlocillin was determined against 403 clinical isolates. At MIC50, piperacillin was 2 to 8 times more active than the other three compounds against Pseudomonas, Escherichia coli, Proteus, Citrobacter, Acinetobacter and Salmonella species. Against Klebsiella, Enterobacter, Haemophilus, Bacteroides spp. and non-beta-lactamase producing Staphylococcus aureus the activity of piperacillin was similar to one or more of the most effective agents. However, azlocillin and mezlocillin were more active than piperacillin against enterococci. Ticarcillin was the least active in vitro. Despite these significant differences at MIC50 amongst the four compounds, they became much less discernible at MIC90, obviously due to beta-lactamase producing strains under study. The spectrum of activity of piperacillin encompasses those of azlocillin and mezlociLlin together except for Gram-positive organisms.

Comparison of the pharmacokinetic and pharmacodynamic activity of piperacillin and mezlocillin.

STUDY OBJECTIVE: To compare serum bactericidal activity over time and pharmacokinetics resulting from single doses of piperacillin (PIP) and a single dose of mezlocillin (MEZ). DESIGN: Open-label, randomized, three-way crossover study. SETTING: Hartford Hospital Clinical Research Center. PATIENTS: Nine healthy volunteers. INTERVENTIONS: Subjects received single doses of PIP 3 and 4 g/70 kg, and a single dose of MEZ 5 g/70 kg. MEASUREMENTS AND MAIN RESULTS: Test organisms were two clinical isolates of Pseudomonas aeruginosa. Pharmacodynamic analysis revealed that PIP 4 g had 2- to 3-fold higher peak serum bactericidal activity at the end of infusion and 4- to 5-fold higher activity at 0.5 hour than did MEZ 5 g, and also provided approximately 1 hour additional activity over MEZ 5 g. Pharmacokinetic analysis revealed that serum concentrations resulting from PIP 4 g remained above the minimum inhibitory concentration of our test strains almost twice as long as MEZ 5 g. CONCLUSION: Since mezlocillin 5 g every 8 hours is currently proving to be effective at many institutions, and since piperacillin 4 g demonstrates superior pharmacokinetic and pharmacodynamic activity, we believe that piperacillin 4 g every 8 hours could be used instead, with resulting cost savings.

Antimicrobial activity of isepamicin (SCH21420, 1-N-HAPA gentamicin B) combinations with cefotaxime, ceftazidime, ceftriaxone, ciprofloxacin, imipenem, mezlocillin and piperacillin tested against gentamicin-resistant and susceptible gram-negative bacilli and enterococci.

Isepamicin, formerly SCH21420 or 1-N-HAPA gentamicin B, is an aminoglycoside that was tested alone or in combination with one of seven broad spectrum drugs against 80 clinical isolates. Half of the strains were gentamicin-resistant but only one isolate (1.3%) was resistant to isepamicin. The broadest spectrum comparison drugs tested alone (ciprofloxacin at 3.8% resistance and imipenem at 5.0% resistance) were associated with the lowest synergy rates when combined with isepamicin. The rank order of synergy (complete or partial) was; cefotaxime = ceftazidime = ceftriaxone = mezlocillin = piperacillin (75% to 80%) greater than imipenem (66%) greater than ciprofloxacin (38%). Isepamicin/ampicillin combinations produced synergistic killing of those enterococci not having high-grade resistance to gentamicin or kanamycin. Enterococcus faecium strains were also refractory to isepamicin/ampicillin synergy. Isepamicin appears to be widely useable against gentamicin-resistant gram-negative bacilli either alone or combined with most commonly used broad spectrum beta-lactams.

In vitro activity of pefloxacin.

A broth dilution method was used to measure the minimal inhibitory concentrations of pefloxacin, a new quinolone derivative. Because this new agent could be used in systemic infections, mezlocillin, cefotaxime, ceftazidime and amikacin were used as comparative agents. Pefloxacin was found to be more active than mezlocillin and as active as or more active than cefotaxime, ceftazidime and amikacin. With the exception of Serratia marcescens, only 7% of Enterobacteriaceae strains were resistant to pefloxacin with a MIC greater than 8 micrograms/ml. Pefloxacin was also found to be the best agent against the non-fermenters Staphylococcus aureus and St. epidermidis. Resistance to ampicillin, carbenicillin and gentamicin did not affect the effectiveness of pefloxacin. However, pefloxacin appeared more susceptible to nalidixic acid resistance, with MICs four to sixfold higher.

In vitro synergy of ciprofloxacin and three other antibiotics against Bacteroides fragilis.

The potential in vitro synergistic effect of ciprofloxacin associated with mezlocillin, cefoxitin and clindamycin was evaluated against 30 strains of Bacteroides fragilis. All bacteria were clinical isolates, identified by gas chromatography and fermentation of carbohydrates. MICs of the drugs were determined by a miniaturized dilution broth method. Resistance or susceptibility to the drugs was not a criterion for the selection of the strains. Antibacterial combinations were tested by a checkerboard method utilizing brain hearth infusion broth and a bacterial inoculum of 10(6) CFU/ml. Microtitre plates were incubated at 37 degrees C for 48 h in anaerobic jars (BBL). Prereduced chopped meat carbohydrate broth was used to store and culture the strains. The effect of antimicrobial combinations was defined on the basis of the fractionary inhibitory concentration (FIC) indexes. We considered: synergistic effect FIC less than or equal to 0.5; additive effect FIC = 0.5-0.75; indifferent effect FIC = 0.76-2.0; antagonism FIC greater than or equal to 2. Ciprofloxacin + clindamycin showed synergistic activity against 10 strains out of 26 (38%); ciprofloxacin + mezlocillin against 9 strains out of 30 (30%); and ciprofloxacin + cefoxitin against 8 out of 29 strains (28%). Each antibiotic combination showed an additive or indifferent effect against all remaining bacteria. The synergistic effect of ciprofloxacin represents an important advantage in allowing the reduction of the dosage of associated drugs such as aminoglycosides or beta-lactams that can potentially be responsible for damage or side-effects.