Vancomycin

Improved Intestinal Mucus Permeation of Vancomycin via Incorporation Into Nanocarrier Containing Papain-Palmitate

The aim of this study was to improve intestinal mucus permeation of a peptide antibiotic via incorporation into papain-palmitate-modified self-emulsifying drug delivery systems (SEDDS) as nanocarrier. Vancomycin as a peptide antibiotic was lipidized by hydrophobic ion pair formation using sodium bis-2-ethylhexyl-sulphosuccinate before incorporation in SEDDS comprising Capmul MCM, propylenglycol, and Kolliphor EL (2:1:2). As mucolytic agent, 0.5% papain-palmitate was introduced in SEDDS formulation containing the vancomycin-sodium bis-2-ethylhexyl-sulphosuccinate ion pair. The formulation was evaluated regarding droplet size, zeta potential, and cytotoxicity using Caco-2 cells previous to intestinal mucus permeation studies using Transwell diffusion and rotating tube method. The hydrophobic ion pair product yielded from surfactant to drug ratio of 3:1 provided a 25-fold increase in lipophilicity, drug payload in SEDDS of 5%, and log D_{SEDDS/release medium} of 2.2. The formulation exhibited a droplet size and zeta potential of 221.5 ± 14.8 nm and -4.2 ± 0.8 mV, respectively. Cytotoxicity study showed that SEDDS formulations were not toxic. Introducing 0.5% papain-palmitate increased the mucus permeability of SEDDS 2.8-fold and 3.3-fold in Transwell diffusion and rotating tube studies, respectively. According to these results, papain decorated SEDDS might be a potential strategy to improve the mucus permeating properties of peptide antibiotics.

Significant Absorption of Oral Vancomycin in a Patient with Clostridium difficile Colitis and Normal Renal Function

Orally-administered vancomycin is poorly absorbed in most patients, usually producing minimal or subtherapeutic serum concentrations. Bowel inflammation may enhance absorption of oral vancomycin, particularly in those with renal failure. A 77-year-old female with Clostridium difficile (C difficile) colitis and normal renal function was treated with high doses of oral vancomycin and achieved serum concentrations in the therapeutic range. To our knowledge, this is the first report of a patient with C difficile colitis and normal renal function to develop therapeutic serum concentrations following oral administration of vancomycin.

Antibiotic side effects

Antibiotic side effects are approached best from an individual agent perspective rather than from a class-related standpoint. As this article indicates, with the exception of drug fevers and drug rashes, most antibiotic side effects are related to individual agents and not class side effects. Clinicians should view antimicrobial side effects as related to each organ system and be aware that more often a nonmicrobial medication is the explanation for the drug side effect rather than the antimicrobial. Nonantimicrobial medications are the most common cause of drug fever; among antimicrobials, beta-lactams and sulfonamides are the most common causes of drug-induced fevers. Antimicrobial side effects have important implications for the patient, legal and economic implications for the hospital, and medicolegal implications for the physician. Antibiotic side effects that prolong hospitalization in today's managed care environment have important economic implications. Clinicians should be familiar with the most common side effects of the most frequently used antimicrobials, to minimize the potential of having adverse reactions occur in patients. Most adverse events related to antimicrobials are reversible rapidly on cessation of the medication. Irreversible toxicities include aminoglycoside-induced ototoxicity, Stevens-Johnson syndrome, and toxicity secondary to nitrofurantoin. The most common acute fatal drug reactions include hypersensitivity reactions resulting in anaphylaxis or the Stevens-Johnson syndrome and fatal hepatic necrosis secondary to trovafloxacin. Clinicians should eliminate the use of drugs associated with chronic or fatal toxicities because multiple therapeutic alternatives exist for virtually every potential infection.

Mississippi mud in the 1990s: risks and outcomes of vancomycin-associated toxicity in general oncology practice

BACKGROUND

Discrepancies between the severity of toxicities reported in early clinical trials and recent clinical experience with vancomycin have led to confusion regarding the need for routine serum vancomycin level monitoring and discontinuation of vancomycin when toxicities occur. Therefore, the authors examined the incidence, outcomes, and predictive factors of vancomycin-associated toxicities in general oncology practice with the goal of developing clinically relevant prediction rules and guidelines.

METHODS

All 742 consecutive cancer patients who received vancomycin at a comprehensive cancer center during a 3-month period were followed prospectively for the development and outcome of phlebitis, rash, ototoxicity, and nephrotoxicity. Logistic regression was used to derive a multiple variable model of the risk of nephrotoxicity. A clinical prediction rule, the Nephrotoxicity Risk Score, was developed from the risk model and validated prospectively.

RESULTS

Phlebitis occurred in 3% of patients (95% confidence interval [95% CI], 2-4%), predominantly those with recently inserted central venous catheters. Rashes occurred in 11% of patients (95% CI, 9-13%); however, all but 4 patients also were receiving beta-lactam antibiotics. Clinical evidence of ototoxicity developed in 6% of patients (95% CI, 4-9%) who were receiving vancomycin plus other ototoxic agents and only 3% of patients (95% CI, 2-5%) not receiving other ototoxic agents (P = 0.08). Nephrotoxicity occurred in 17% of patients (95% CI, 15-20%). Logistic regression revealed that factors associated with an increased risk of nephrotoxicity included administration of other mild to moderate (P = 0.01) or severely nephrotoxic agents (P < 0.001) or an acute physiology and chronic health evaluation (APACHE) score > 40 (P = 0.002). Elevated serum vancomycin peak levels did not reliably predict subsequent nephrotoxicity.

CONCLUSIONS

Vancomycin-associated toxicities usually are mild and self-limiting. Some patients are at a significantly higher risk of nephrotoxicity but the authors believe these individuals can be identified reliably with the Nephrotoxicity Risk Index using information available at vancomycin initiation. Further testing of the Nephrotoxicity Risk Index is ongoing.

Calculation of concentrations of equilibrium components in an in vitro activity test of vancomycin antibiotics and the possible mode of action

The vancomycin group of antibiotics is considered to act by binding the bacterial cell wall mucopeptide precursor terminating in -L-Lys-D-Ala-D-Ala. The dimerization of these antibiotics is also believed to play a role in the action. In this paper, we analyzed the equilibria in the in vitro antibacterial activity test of the vancomycin antibiotics both with and without the cell wall precursor analogue di-acetyl-L-Lys-D-Ala-D-Ala (DALAA). Based on the equilibria and concentration balance, we obtained 10 equations (seven quadratic equations and three linear equations) containing 10 equilibrium concentrations which relate to the antibiotic, cell wall precursor and DALAA. A computer program was written to solve these equations from known dimerization constant and the binding constants (both monomer and dimer) with DALAA of the antibiotic. The concentrations in the test for vancomycin and eremomycin were obtained. The antibiotic activity of these antibiotics may be quantitatively correlated with their dimerization constants and the binding constants through the calculation. By analyzing the calculated results, we concluded that the cell wall-bound dimer may be the major contributor to the antibiotic activity in the case of eremomycin, while the cell wall-bound monomer is possibly the determinant for the activity of vancomycin.

The structure of an asymmetric dimer relevant to the mode of action of the glycopeptide antibiotics

BACKGROUND

Glycopeptide antibiotics of the vancomycin group are of crucial clinical importance in the treatment of methicillin resistant Staphylococcus aureus (MRSA)--the often lethal 'super-bug'--characterized by its resistance to a wide range of antibiotics in common use. The antibiotics exert their physiological action by blocking cell wall synthesis through recognition of nascent cell wall mucopeptides terminating in the sequence -D-Ala-D-Ala. Evidence suggests that the antibiotics are able to enhance their biological activity by the formation of homodimers, and this is supported by the observation that dimerization and peptide binding in vitro are cooperative phenomena. The basis of this enhancement is not understood at the molecular level.

RESULTS

The first detailed structure of a dimeric glycopeptide antibiotic, that of eremomycin, is presented based upon solution NMR data. The overall structure of the dimer complex is asymmetric. The source of this asymmetry--a parallel alignment and mutual interaction of the disaccharides--appears to promote dimerization through specific sugar-sugar recognition.

CONCLUSIONS

A molecular basis for the observed cooperativity of cell wall peptide binding by eremomycin is evident from these studies of the dimer. The carboxylate anion of the cell wall component, which is crucial to binding, forms an amide-mediated ion-pair interaction to the alkylammonium ion of the ring 6 sugar in the other half of the dimer making the structure and positioning of this sugar important in mediating cooperativity.

Resistance to vancomycin and teicoplanin: an emerging clinical problem

Vancomycin and teicoplanin are glycopeptides active against a wide range of gram-positive bacteria. For 30 years following the discovery of vancomycin in 1956, vancomycin resistance was not detected among normally susceptible bacteria recovered from human specimens. Since 1986, however, bacteria resistant to vancomycin or teicoplanin or both have been described. Strains of the genera Leuconostoc, Lactobacillus, Pediococcus, and Erysipelothrix seem inherently resistant to glycopeptides. Species and strains of enterococci and coagulase-negative staphylococci appear to have acquired or developed resistance. There are at least two categories of glycopeptide resistance among enterococci, characterized by either high-level resistance to vancomycin (MIC, greater than or equal to 64 mg/liter) and teicoplanin (MIC, greater than or equal to 8 mg/liter) or lower-level vancomycin resistance (MIC, 32 to 64 mg/liter) and teicoplanin susceptibility (MIC, less than or equal to 1 mg/liter). The two categories appear to have similar resistance mechanisms, although genetic and biochemical studies indicate that they have arisen independently. Among coagulase-negative staphylococci, strains for which vancomycin MICs are up to 20 mg/liter or teicoplanin MICs are 16 to 32 mg/liter have been reported, but cross-resistance between these glycopeptides varies. The selective advantage accorded to glycopeptide-resistant bacteria and the observation that high-level resistance in enterococci is transferable suggest that such resistance may be expected to increase in incidence. Clinicians and microbiologists need to be aware of this emerging problem.

Methicillin-resistant Staphylococcus aureus: pediatric perspective

Methicillin-resistant S. aureus has emerged as a nosocomial pathogen of major importance in pediatric patients. Infection occurs most often in hospitalized individuals with underlying predisposing medical conditions. Any body site may be involved, and bacteremia frequently occurs concomitantly. Vancomycin is the antibiotic of choice for serious MRSA infections; PRPs and cephalosporins generally are not effective. The likelihood of an adverse outcome of infection increases with the severity of an underlying condition and delay in institution of appropriate therapy. Infection control measures have met with only limited success in eradicating MRSA from the hospital environment. Methicillin-resistant S. aureus is likely to remain of considerable clinical significance to physicians caring for seriously ill children.

Corynebacterium Group JK pathogen in cerebrospinal fluid shunt infection. Report of two cases

The clinical and laboratory findings in two cases of aerobic Corynebacterium Group JK infection of cerebrospinal fluid (CSF) shunts are described. These organisms have occasionally been reported as a cause of serious infections in man but have not been reported as a cause of shunt infection. In both cases, CSF pleocytosis was limited to 20 or 60 cells with variable protein and sugar values. Fever was a constant finding, frequently accompanied by signs of central nervous system dysfunction. Corynebacterium Group JK organisms are common contaminants of the normal skin flora. When isolated from the blood and/or the CSF of a patient with a CSF shunt who has symptoms and signs compatible with infection, the organism should not be dismissed as a contaminant. A significant feature of this group is its resistance to almost all presently available antibiotics including penicillin, the cephalosporins, and the aminoglycosides. These organisms are, however, sensitive to vancomycin.

Evaluation of a new vancomycin dosing method

Thirty-one patients who were prescribed vancomycin therapy at our institution since January 1, 1986, were dosed using the guidelines as described by Lake and Peterson. Peak and trough vancomycin serum concentrations were measured at steady state: 24 (77%) peak serum concentrations were within the range of 20-30 mg/L, and 24 (77%) trough serum concentrations were within the range of 5-10 mg/L. We have found that the method of Lake and Peterson is satisfactory for initiating vancomycin therapy in most patients. Some, however, may not achieve optimal serum concentrations using these guidelines alone, and their regimens may have to be adjusted based upon actual serum concentration data.

Adverse effects of vancomycin administered in the perioperative period

Indications for the administration of vancomycin in the perioperative period have expanded in recent years. Used in this situation, vancomycin has caused adverse reactions, the most serious of which is hypotension. We describe five patients who had adverse reactions to vancomycin perioperatively. Vancomycin-induced hypotension usually results from a negative inotropic and vasodilator effect produced in part by a histamine-release phenomenon, which occurs most commonly with rapid intravenous infusion of the drug. Such a release of histamine may also produce an acute urticarial flushing of the upper torso (the "red neck syndrome") and symptoms of pain and muscle spasm in the chest or paraspinal muscles, which may mimic myocardial infarction. These effects usually abate promptly when the infusion of vancomycin is discontinued, and their resolution may be expedited by administration of an antihistamine.

Staphylococcus epidermidis sepsis in pediatric patients: clinical and therapeutic considerations

This report concerns 60 children with documented Staphylococcus epidermidis sepsis. There were 34 boys and 26 girls, ages 2 weeks to 15 years. The primary diagnosis included malignancy (13), congenital (13) or acquired (11) gastrointestinal disorders, prematurity (7), cardiac defect (5), hydrocephalus (2) and miscellaneous (9). Clinical presentation included fever (54), tachycardia (15), lethargy (20), hypotension (8), irritability (6), increased gastric residuals (6) and apnea/bradycardia (3). A documented source of sepsis was noted in 56 patients, including percutaneous central venous catheters (23), Broviac catheters (17), umbilical arterial catheters (6), wound (3), V-P shunt (2), cardiac defect (2), cholangitis (1), chest tube (1) and peripheral arterial line (1). There were six sepsis-related deaths, four in premature infants. Two of six infected subclavian catheters were treated successfully with vancomycin. Infection was successfully cleared in 20 of 23 infected Broviac catheters with vancomycin through the line. However, six were eventually removed for tract infection (1), persistent fever (2), and Candida sp. infection (3). Although once considered a non-pathogenic skin contaminant, S. epidermidis has emerged as a serious pathogen in hospitalized, immunosuppressed, premature and malnourished pediatric patients. Indwelling catheters enhance the likelihood of infection in these patients. Aggressive antimicrobial therapy is vital in this potentially lethal infection. Vancomycin proved efficacious in this series.