Antibacterial activity of ticarcillin in the presence of clavulanate potassium

Overcoming Beta-Lactamase-Based Antimicrobial Resistance by Nanocarrier-Loaded Clavulanic Acid and Antibiotic Cotreatments

Antimicrobial resistance (AMR) is one of the major threats to modern healthcare. Many types of bacteria have developed resistance to multiple antibiotic treatments, while additional antibiotics have not been recently brought to market. One approach to counter AMR based on the beta-lactamase enzyme has been to use cotreatments of an antibiotic and an inhibitor, to enhance the antibiotic action. Here, we aimed to enhance this technique by developing nanocarriers of two cationic beta-lactam class antibiotics, amoxicillin, and ticarcillin, combined with a beta-lactamase inhibitor, clavulanic acid, which can potentially overcome this type of AMR. We demonstrate for the first time that beta-lactamase inhibitor-loaded nanocarriers in cotreatments with either free or nanocarrier-loaded beta-lactam antibiotics can enhance their effectiveness further than when used alone. We use surface-functionalized shellac-/Poloxamer 407-stabilized antibiotic nanocarriers on Pseudomonas aeruginosa, which is susceptible to ticarcillin but is resistant to amoxicillin. We show an amplification of the antibiotic effect of amoxicillin and ticarcillin loaded in shellac nanoparticles, both alone and as a cotreatment with free or nanocarrier-loaded clavulanic acid. We also report a significant increase in the antimicrobial effects of clavulanic acid loaded in such nanocarriers as a cotreatment. We explain the increased antimicrobial activity of the cationically functionalized antibiotic-loaded nanoparticles with electrostatic attraction to the bacterial cell wall, which delivers higher local antibiotic and inhibitor concentrations. The effect is due to the accumulation of the clavulanic acid-loaded nanocarriers on the bacterial cell walls that allows a higher proportion of the inhibitor to engage with the produced intracellular beta-lactamases. These nanocarriers were also found to have a very low cytotoxic effect against human keratinocytes, which shows great potential for overcoming enzyme-based AMR.

Continuous infusion of ticarcillin-clavulanate for home treatment of serious infections: clinical efficacy, safety, pharmacokinetics and pharmacodynamics

Continuous infusion (CI) ticarcillin-clavulanate is a potential therapeutic improvement over conventional intermittent dosing because the major pharmacodynamic (PD) predictor of efficacy of beta-lactams is the time that free drug levels exceed the MIC. This study incorporated a 6-year retrospective arm evaluating efficacy and safety of CI ticarcillin-clavulanate in the home treatment of serious infections and a prospective arm additionally evaluating pharmacokinetics (PK) and PD. In the prospective arm, steady-state serum ticarcillin and clavulanate levels and MIC testing of significant pathogens were performed. One hundred and twelve patients (median age, 56 years) were treated with a CI dose of 9.3-12.4g/day and mean CI duration of 18.0 days. Infections treated included osteomyelitis (50 patients), septic arthritis (6), cellulitis (17), pulmonary infections (12), febrile neutropenia (7), vascular infections (7), intra-abdominal infections (2), and Gram-negative endocarditis (2); 91/112 (81%) of patients were cured, 14 (13%) had partial response and 7 (6%) failed therapy. Nine patients had PICC line complications and five patients had drug adverse events. Eighteen patients had prospective PK/PD assessment although only four patients had sufficient data for a full PK/PD evaluation (both serum steady-state drug levels and ticarcillin and clavulanate MICs from a bacteriological isolate), as this was difficult to obtain in home-based patients, particularly as serum clavulanate levels were found to deteriorate rapidly on storage. Three of four patients with matched PK/PD assessment had free drug levels exceeding the MIC of the pathogen. Home CI of ticarcillin-clavulanate is a safe, effective, convenient and practical therapy and is a therapeutic advance over traditional intermittent dosing when used in the home setting.

Antibiotics in neonatal infections: a review

The bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group B streptococci, enterococci, Enterobacteriaceae and Listeria monocytogenes. Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. The primary objective of the paediatrician is to identity all potential cases of bacterial disease quickly and begin antibacterial treatment immediately after the appropriate cultures have been obtained. Combination therapy is recommended for initial empirical treatment in the neonate. In early-onset infections, an effective first-line empirical therapy is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cefotaxime, a combination particularly useful in neonatal meningitis (mean duration of treatment 14 to 21 days), in patients at risk of nephrotoxicity and/or when therapeutic monitoring of aminoglycosides is not possible. Another potential substitute for the aminoglycoside is aztreonam. Triple combination therapy (such as amoxicillin plus cefotaxime and an aminoglycoside) could also be used for the first 2 to 3 days of life, followed by dual therapy after the microbiological results. In late-onset infections the combination oxacillin plus an aminoglycoside is widely recommended. However, vancomycin plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days) may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local bacterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents if a specific organism has been identified, and should be discontinued if cultures are negative and the neonate is in good clinical condition. Penicillins and third-generation cephalosporins are generally well tolerated in neonates. There is controversy regarding whether therapeutic drug monitoring of aminoglycosides will decrease toxicity (particularly renal damage) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin are uncommon, but debate still exists over the need for therapeutic drug monitoring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particularly prone to antibacterial-induced toxicity.

Abnormal physiological properties and altered cell wall composition in Streptococcus pneumoniae grown in the presence of clavulanic acid

Subinhibitory concentrations of clavulanate caused premature induction of stationary-phase autolysis, sensitization to lysozyme, and reductions in the MICs of deoxycholate and penicillin for Streptococcus pneumoniae. In the range of clavulanate concentrations producing these effects, this beta-lactam compound was selectively bound to PBP 3. Cell walls isolated from pneumococci grown in the presence of clavulanate showed increased sensitivity to the hydrolytic action of purified pneumococcal autolysin in vitro. High-performance liquid chromatography analysis of the peptidoglycan isolated from the clavulanate-grown cells showed major qualitative and quantitative changes in stem peptide composition, the most striking feature of which was the accumulation of peptide species carrying intact D-alanyl-D-alanine residues at the carboxy termini. The altered biological and biochemical properties of the clavulanate-grown pneumococci appear to be the consequences of suppressed D,D-carboxypeptidase activity.

Ticarcillin-clavulanic acid pharmacokinetics in preterm neonates with presumed sepsis

The objective of the reported study was to characterize the pharmacokinetics of ticarcillin and clavulanic acid in premature low-birth-weight (less than 2,200 g) neonates with presumed sepsis. Eleven infants received 12 courses of ticarcillin-clavulanic acid at 75 mg/kg of body weight intravenously every 12 h. Blood samples were collected at 0.5, 1.5, 4, and 8 h following the infusion of the initial dose. The concentrations of ticarcillin and clavulanic acid were determined by a microbiologic assay. Median (interpatient coefficients of variation) values for the volume of the central compartment, total steady-state volume, distributional clearance, total clearance, and terminal elimination half-life for ticarcillin were 0.030 liter/kg (21%), 0.26 liter/kg (48%), 0.41 liter/h/kg (47%), 0.047 liter/h/kg (47%), and 4.2 h (45%), respectively. For clavulanic acid the parameters were 0.28 liter/kg (32%), 0.36 liter/kg (34%), 11 liters/h/kg (36%), 0.12 liters/h/kg (72%), and 1.95 h (40%), respectively. Our results suggest that the current dosing recommendations of 75 mg/kg every 12 h risk subtherapeutic clavulanic acid concentrations and that 50 mg/kg every 6 h is a more rational dosing strategy.

Advances in the pharmacotherapy of cystic fibrosis

The quality of life and life-span of cystic fibrosis patients have been improved substantially in the last 20 or 30 years. This has been accomplished largely through improved early diagnosis and advances in traditional pharmacotherapy which mainly consists of antibiotic therapy. In the past few years, the basic cellular defect of cystic fibrosis, as well as the gene determining the disease, have been described. These milestones in the quest for knowledge about the disease open the door for other innovative forms of therapy. While corrective gene therapy may be the ultimate result of advances made based upon this new knowledge, we will probably see earlier breakthroughs in the form of immune reaction inhibition and correction of ion flux disturbances. Each of these present and future forms of therapy is explored in this paper.

Efficacy of ticarcillin-clavulanic acid for treatment of experimental Staphylococcus aureus endocarditis in rats

The efficacy of ticarcillin-clavulanic acid was compared with the efficacies of standard antistaphylococcal agents (flucloxacillin, oxacillin, nafcillin, and vancomycin) and ticarcillin in an experimental model of Staphylococcus aureus endocarditis. Therapy was either initiated soon (8 h) after infection, when numbers of bacteria in aortic valve vegetations were relatively low (approximately 6 to 8 log10 CFU/g), or delayed until 24 h after infection, when the vegetations usually contained greater than 9 log10 CFU/g. Doses of the antibiotic were selected to produce peak concentrations in rat serum similar to those achievable in humans after administration of parenteral therapeutic doses. Ticarcillin-clavulanic acid was more effective overall than ticarcillin alone against endocarditis caused by beta-lactamase-producing strains of S. aureus, illustrating the beta-lactamase-inhibitory activity of clavulanic acid in vivo. Ticarcillin-clavulanic acid was as effective as the standard antistaphylococcal beta-lactam agents flucloxacillin, oxacillin, and nafcillin in these infections, whereas vancomycin was generally less active. These results illustrate the clinical potential of ticarcillin-clavulanic acid in the prophylaxis or therapy of severe staphylococcal infections.

Comparative efficacies of ticarcillin, ticarcillin/clavulanic acid, piperacillin and cefoxitin against polymicrobial infections in mice caused by Escherichia coli and Bacteroides fragilis

A model of localised abscess formation was used to establish mixed infections caused by Escherichia coli and Bacteroides fragilis. The beta-lactamase producing, ticarcillin-resistant strains E. coli E96 and B. fragilis VPI 8708 were used to produce one infection, and in another infection, a beta-lactamase hyperproducing strain E. coli 41548 was combined with a ticarcillin-susceptible strain, B. fragilis B3. Treatment, at doses producing clinically achievable concentrations in mouse serum, began 1 h after inoculation, and continued three times daily for four days. Bacterial numbers in infected tissue were measured at intervals. Against both infections, ticarcillin was ineffective in preventing bacterial growth and abscess formation in all mice. Piperacillin prevented abscess formation in 60% of the mice infected with E. coli E96/B. fragilis VPI 8708, and in 40% of those in the E. coli 41548/B. fragilis B3 group. Therapy with ticarcillin/clavulanic acid or cefoxitin reduced the number of both organisms at the site of infection, and thus prevented abscess formation in 100% treated animals.

Simulation of human serum pharmacokinetics of ticarcillin-clavulanic acid and ceftazidime in rabbits, and efficacy against experimental Klebsiella pneumoniae meningitis

The penetration into cerebrospinal fluid (CSF) and efficacy of ticarcillin-clavulanic acid, ticarcillin alone, and ceftazidime were compared in rabbits with experimentally induced Klebsiella pneumoniae meningitis. The compounds were administered to simulate in rabbit plasma the concentration-versus-time curves observed in humans after 30-min infusions of Timentin (3 g of ticarcillin plus 100 mg of clavulanic acid), ticarcillin (3 g), and ceftazidime (2 g). Single- and multiple-dosing schedules were used. The penetrations of clavulanic acid into CSF (expressed as [area under the concentration-time curve for CSF/area under the curve for plasma] x 100) after the two dosing schedules were 28 and 24.5%, similar to that for ceftazidime (21%; multiple-dosing only) and greater than those for ticarcillin (8.4 and 9.3%). Ticarcillin was ineffective in reducing viable counts in CSF but, in the presence of clavulanic acid, reduced bacterial numbers by approximately 99% at 4 h after a single dose and by 99.99% at 12 h after three doses given at 4-h intervals. Two doses of ceftazidime given 8 h apart were more effective than the three doses of ticarcillin-clavulanic acid, in keeping with the in vitro activities of these compounds against the infecting organism. These results illustrate the ability of clavulanic acid to penetrate the blood-CSF barrier such that concentrations of the inhibitor in CSF potentiate the activity of ticarcillin against the ticarcillin-resistant, beta-lactamase-producing strain of K. pneumoniae.

Comparative in vitro susceptibilities of 504 bacteremic isolates to ticarcillin plus clavulanic acid and other antimicrobial agents

A total of 504 clinical bacteremic isolates were tested for susceptibility to ticarcillin-clavulanic acid and 12 other antibiotics. Ticarcillin-clavulanic acid showed superior antibacterial activity compared to penicillin, mezlocillin, piperacillin, ticarcillin, gentamicin, and amikacin against bacteremic isolates of methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis. However, ticarcillin-clavulanic acid's activity was inferior to that of vancomycin against methicillin-resistant isolates of S. aureus and S. epidermidis. For Escherichia coli, Klebsiella oxytoca, Proteus mirabilis, Providencia stuartii, and lactose nonfermenting aerobic gram-negative bacilli, the activity of ticarcillin-clavulanic acid surpassed that of mezlocillin, piperacillin, and ticarcillin. Of the antimicrobial agents tested, ticarcillin, piperacillin, ceftazidime, and amikacin were the most active antibiotics against Pseudomonas aeruginosa.

Resistance to ticarcillin-potassium clavulanate among clinical isolates of the family Enterobacteriaceae: role of PSE-1 beta-lactamase and high levels of TEM-1 and SHV-1 and problems with false susceptibility in disk diffusion tests

Thirty-four clinical isolates of the family Enterobacteriaceae from the University of Texas M. D. Anderson Cancer Center appeared resistant to ticarcillin-potassium clavulanate in agar dilution and broth macrodilution tests. Among those isolates producing a single non-class I beta-lactamase, resistance was due to production of high levels of TEM-1, SHV-1, or class IV enzymes. In five Escherichia coli isolates, production of low levels of PSE-1 was responsible for resistance which seemed due to rapid hydrolysis of ticarcillin rather than diminished susceptibility of PSE-1 to inhibition by potassium clavulanate. Comparisons of dilution and disk diffusion tests revealed major discrepancies, with 65% false susceptibility in the disk test. Revision of the interpretive criteria used for disk diffusion tests from less than or equal to 11 to less than or equal to 18 mm for resistance is proposed to resolve these discrepancies until clinical data are obtained which can be used to determine which in vitro test is most predictive of therapeutic outcome. These new criteria would diminish false susceptibility without introducing false resistance.

Effect of clavulanic acid on the susceptibility of clinical anaerobic bacteria to ticarcillin: a multicenter study

Over 2,000 recent clinical isolates of anaerobic bacteria were tested at five medical centers for susceptibility to ticarcillin, ticarcillin plus clavulanic acid, clindamycin, and metronidazole. At 64 micrograms/ml, ticarcillin inhibited 92% of all isolates, but 98% were inhibited at this concentration when 2 micrograms/ml of clavulanic acid was added. With different Bacteroides species, clavulanic acid reduced ticarcillin MICs 2- to 32-fold; other anaerobic species were not significantly affected.

Pharmacokinetics and distribution of ticarcillin-clavulanic acid (Timentin) in experimental animals

The pharmacokinetics and distribution of ticarcillin and clavulanic acid were studied in rats and rabbits after intravenous coadministration of the compounds. The elimination half-lives for ticarcillin and clavulanic acid were similar in both rats (ticarcillin, 0.22 h; clavulanic acid, 0.24 h) and rabbits (ticarcillin, 0.38 h; clavulanic acid, 0.31 h). Both compounds distributed widely throughout rat tissues, and the patterns of distribution were similar to those observed for other beta-lactams. Values for penetration into rat pleural, peritoneal, and subcutaneous fluids calculated from the equation (AUCfluid/AUCserum) X 100, where AUC is the area under the concentration-time curve, were between 83 and 93% for ticarcillin and 86 and 103% for clavulanic acid. Values for penetration into tissue cages in rabbits were 139% +/- 45% for ticarcillin and 109% +/- 22% for clavulanic acid. The penetration of clavulanic acid into rabbit cerebrospinal fluid was higher (P less than 0.05) (4.0% +/- 0.61%) than that of ticarcillin (1.3% +/- 0.53%). Overall, the results show that ticarcillin and clavulanic acid distribute readily throughout body tissues and fluids and predict that the penicillin and beta-lactamase inhibitor would be present together at sites of infection.

Pharmacokinetics of ticarcillin and clavulanic acid (timentin) in relation to renal function

The disposition of coadministered ticarcillin (3 g/1.73 m2) and clavulanic acid (100 mg/1.73 m2) was examined after a 30-min infusion in 24 noninfected subjects with various degrees of renal function. Noncompartmental pharmacokinetic parameters for the individual compounds were determined from plasma concentrations and urinary excretion rates. All clearances (total, renal, and nonrenal) and urinary recoveries of unchanged drug were found to be linearly related to creatinine clearance (CLCR). The steady-state volume of distribution (9.9 and 12.9 liters for ticarcillin and clavulanic acid) approximated the extracellular fluid space and was not related to CLCR. The half-lives increased with reduced renal function and ranged from 56 to 392 min for ticarcillin and 26 to 266 min for clavulanic acid. The clearances of both drugs decreased proportionately with reduction in renal function, facilitating dosing adjustments based on CLCR. Calculations of expected steady-state maximum and minimum concentrations in plasma using constant doses and an extended dosing interval related to CLCR further rationalized use of the 30:1 drug combination ratio for all patients.

Bactericidal effects of ticarcillin-clavulanic acid against beta-lactamase-producing bacteria in vivo

The comparative efficacies of ticarcillin and ticarcillin plus clavulanic acid have been determined in the mouse against experimental infections caused by ticarcillin-resistant bacteria. The infections studied comprised an intraperitoneal infection, local tissue infections, pyelonephritis, and pneumonia. Both ticarcillin and clavulanic acid penetrated readily to the sites of infection studied and at the doses employed were present at concentrations of the same order as those obtained in humans after the administration of ticarcillin-clavulanic acid formulations (Timentin; Beecham). At these concentrations, the ticarcillin-clavulanic acid combination caused significant bactericidal effects at the sites of infection against the ticarcillin-resistant strains of Bacteroides fragilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus investigated. The efficacy of ticarcillin plus clavulanic acid against the infections resistant to therapy with ticarcillin demonstrated the beta-lactamase-inhibitory activity of clavulanic acid in vivo.