Endotoxin increases the nephrotoxic potential of gentamicin and vancomycin plus gentamicin

Acute kidney injury following contrast media administration in the septic patient: A retrospective propensity-matched analysis

PURPOSE

To determine the risk for acute kidney injury (AKI) attributable to intravenous contrast media (CM) administration in septic patients.

MATERIALS AND METHODS

This was a single-center retrospective propensity matched cohort analysis performed in the emergency department (ED) of an academic medical center. All visits for patients ≥18 years who met sepsis diagnostic criteria and had serum creatinine (SCr) measured both on arrival to the ED and again 48 to 72 h later were included. Of 4171 visits, 1464 patients underwent contrast-enhanced CT (CECT), 976 underwent unenhanced CT and 1731 underwent no CT at all.

RESULTS

The primary outcome was incidence of AKI. Logistic regression and between-groups odds ratios with and without propensity-score matching were used to test for an independent association between CM administration and AKI. Incidence of AKI was 7.2%, 9.4% and 9.7% in those who underwent CECT, unenhanced CT and no CT. CM administration was not associated with increased incidence of AKI.

CONCLUSIONS

Sepsis is a medical emergency proven to benefit from early diagnosis and rapid initiation of treatment, which is often aided by CECT. Our findings argue against withholding CM for fear of precipitating AKI in potentially septic patients.

Vancomycin and the Risk of AKI: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Vancomycin has been in use for more than half a century, but whether it is truly nephrotoxic and to what extent are still highly controversial. The objective of this study was to determine the risk of AKI attributable to intravenous vancomycin.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a systematic review of randomized, controlled trials and cohort studies that compared patients treated with intravenous vancomycin with a control group of patients given a comparator nonglycopeptide antibiotic and in which kidney function or kidney injury outcomes were reported. PubMed and Cochrane Library were searched from 1990 to September of 2015. Two reviewers extracted data and assessed study risk of bias, and one reviewer adjudicated the assessments. A meta-analysis was conducted on seven randomized, controlled trials (total of 4033 patients).

RESULTS

Moderate quality evidence suggested that vancomycin treatment is associated with a higher risk of AKI, with a relative risk of 2.45 (95% confidence interval, 1.69 to 3.55). The risk of kidney injury was similar in patients treated for skin and soft tissue infections compared with those treated for nosocomial pneumonia and other complicated infections. There was an uncertain risk of reporting bias, because kidney function was not a prespecified outcome in any of the trials. The preponderance of evidence was judged to be indirect, because the majority of studies compared vancomycin specifically with linezolid.

CONCLUSIONS

Our findings suggest that there is a measurable risk of AKI associated with vancomycin, but the strength of the evidence is moderate. A randomized, controlled trial designed to study kidney function as an outcome would be needed to draw unequivocal conclusions.

Vancomycin revisited: a reappraisal of clinical use

Vancomycin has been used for decades to treat serious systemic gram positive infections. Extensive use over time has demonstrated vancomycin is not nephrotoxic even when used in high dosage, i.e., twice the usual dose. Since vancomycin is not nephrotoxic, there is no rationale for dosing vancomycin based on serum vancomycin levels. Since vancomycin is eliminated by GFR, vancomycin dosing should be based on creatinine clearance. Vancomycin obeys "concentration dependent" kinetics and higher than usual doses may be useful in some infections (eg, osteomyelitis). Widespread vancomycin use has resulted in increased VRE prevalence worldwide. Among staphylococci, vancomycin induced cell wall thickening results in "permeability mediated" resistance to vancomycin, as well as other anti-staphylococcal antibiotics. "Permeability mediated" resistance accounts for the common clinical observation that MRSA infections treated with vancomycin often resolve slowly or not at all. Other effective MRSA antibiotics are available (eg, linezolid, daptomycin, minocycline, or tigecycline) and are more reliably effective, do not increase staphylococcal resistance or increase VRE prevalence.

Ceftriaxone pharmacokinetics in interleukin-10-treated murine pneumococcal pneumonia

OBJECTIVES

Anti-inflammatory therapy with interleukin-10 (IL-10) was previously reported to reduce pulmonary inflammation and to prevent septicaemia in murine pneumococcal pneumonia treated with ceftriaxone. In the present report, we investigated the influence of pulmonary infection and IL-10 administration on the pharmacokinetics of ceftriaxone.

METHODS

CD1 mice were infected with 10(7) cfu of Streptococcus pneumoniae. Treatments (intraperitoneal) with IL-10 (1 microg per mouse), ceftriaxone (20 mg/kg) or the combination of IL-10 + ceftriaxone were initiated 18 h after infection. Groups of mice were sacrificed at several time points from 5 min to 24 h after initiation of therapy. Ceftriaxone was quantified in blood and lungs using a microbiological assay. Additional groups of mice received a second dose of IL-10 at 36 h post-infection. Survival rates were recorded over 14 days.

RESULTS

The clearance of ceftriaxone was significantly reduced in infected mice compared with that in non-infected animals (P < 0.01), whereas AUC, mean residence time, t(1/2) and AUC(lung)/AUC(serum) were significantly enhanced (P < 0.01, 0.01, 0.05, 0.05). Co-administration of IL-10 with ceftriaxone in infected animals further retained ceftriaxone in the bloodstream and reduced its volume of distribution at steady state and the ratio of AUC(lung)/AUC(serum). IL-10 alone did not modify significantly the pharmacokinetics of ceftriaxone in blood and lungs of non-infected animals.

CONCLUSIONS

The results suggest that pulmonary infection, and therapy with IL-10, both affect the pharmacokinetics of ceftriaxone. Indeed, administration of IL-10 + ceftriaxone improved the survival rate of mice (P < 0.001 compared with therapy with ceftriaxone alone). IL-10 should be considered as an adjunctive therapy to antibiotics against severe infections.

Antibiotic-induced release of inflammatory mediators from bacteria in experimentalKlebsiella pneumoniae-induced sepsis

In a fibrin-clot model of sepsis, developed in mice, treatment with the antibiotics ceftazidime (Cfz) and ofloxacin (Ofl) caused significant (p < 0.01) release of endotoxin and TNF-alpha after 4.5 h when compared with control (untreated) and amikacin (Ami) treated group. Except for control group, the level of bacteremia declined in all three antibiotic-treated groups. The results suggest that antibiotic therapy, irrespective of the agent used, results in an increase in endotoxin levels in vivo. The amount of endotoxin liberated by Ami was much smaller than with Cfz and Ofl therapy, which makes it an appropriate agent for the treatment of sepsis. An increase in the level of TNF-alpha along with endotoxin is suggestive of increased inflammatory response.

Aminoglycoside nephrotoxicity: do time and frequency of administration matter?

Aminoglycosides remains the mainstay in the treatment of gram-negative infections despite their potential oto-and nephrotoxicity although alternatives with equal or better efficacy are available. Several approaches were investigated to decrease aminoglycosides nephrotoxicity. Among them, only the once-daily dosing of aminoglycosides has been brought to the clinic and physicians are now increasingly adopting this approach to reduce the toxicity of these agents. The incidence of aminoglycoside nephrotoxicity can be further reduced in view of the recent data on the circadian variations of their nephrotoxicity. In fact, it has been clearly demonstrated in both experimental animals and humans that the toxicity is maximal when the drug is injected during the rest period compared with the activity period. Thus, injecting aminoglycosides once-daily at the time of the lowest toxicity is actually the most interesting and clinically applicable approach to reduce aminoglycosides toxicity.

Pharmacologic Basis for the Treatment of Pyelonephritis

Urinary tract infections (UTIs) are among the most common bacterial infections in humans. Even though physicians have been treating UTIs for 60 years, there has been no standardized approach regarding the rational choice of antimicrobial agents and optimal treatment duration for these infections. This review discusses the pharmacologic basis for the treatment of UTIs. Although most antibiotics concentrate well in the urine and can eradicate most of the sensitive uropathogens that cause lower UTI, antibiotics given for the treatment of pyelonephritis must concentrate and kill bacteria embedded within the renal parenchyma. Investigators once believed that antibiotics must concentrate in sufficient amounts in the urine of infected patients to be effective in treating pyelonephritis. In fact, the efficacy of an antibiotic in the treatment of pyelonephritis is proportional to its capacity to converge in high concentration not only in urine but also in the renal parenchyma because serum and urine levels of antibiotics are poor predictors of the intrarenal levels. Other factors should also be taken into consideration in the management of UTIs, such as the time of day antibiotics are given because significant time-dependent differences have been observed in the pharmacokinetics and rate of excretion in urine of several antibiotics. Finally, the authors review the recent development in the inflammatory response in the urinary tract that may explain the clinical features of UTI and may be useful in the diagnosis as well as better management of UTI.

Salmonella typhimurium porin internalization by leukocytes

The location of Salmonella typhimurium porins has been found in human monocytes and lymphocytes by means of high resolution autoradiography. The results indicate that traces of porins are frequently visible on ultrathin sections of treated human lymphomonocytes and that they are located especially in the nuclear areas.

Acute renal failure in infants, children and adults

Acute renal failure (ARF) occurs in many critically ill patients regardless of age. A combination of events often seen in critical care settings, including shock, sepsis, hypoxia, and the use of potentially nephrotoxic medications, combine to make ARF an ongoing and important management issue in critical care medicine. Since the events leading to the development of ARF differ in infants, children, adults, and the elderly, the pathophysiology, clinical features, and treatment modalities do indeed have remarkable similarities among the different age groups.

Effect of endotoxin on gentamicin pharmacokinetics in old and young adult rats

The effect of endotoxin administration on gentamicin pharmacokinetics in young adult (2-3 months) and old (22-24 months) rats was studied. Gentamicin (3 mg/kg, iv) was administered 24 hours after an endotoxin challenge (5 mg/kg, ip). Some blood biochemical parameters, viz. urea, AST, GGT activities in addition to PCV and Hb concentration and creatinine clearance were also measured. In young animals, endotoxin caused prolongation in gentamicin half life (t1/2), increased area under the plasma concentration-time curve (AUC) and reduced total body clearance (ClB) and volume of distribution (Vd). Endotoxin effects in the old rats were qualitatively similar to those induced in the young but were more pronounced. They included more than 10 fold increase in the t1/2 and AUC. In addition, a rising early phase in gentamicin plasma concentration was noticed in old rats treated with endotoxin which was, probably, due to an early redistribution process of gentamicin. The results indicate that aging and endotoxin, individually, can significantly alter gentamicin pharmacokinetics in the rat. These alterations were exacerbated when endotoxemia was induced in old rats.

Nephrotoxicity of gentamicin and vancomycin given alone and in combination as determined by enzymuria and cortical antibiotic levels in rats

The purpose of this study was to compare the nephrotoxicity of gentamicin and vancomycin alone and in combination. Thirty-two male Sprague-Dawley rats were randomized into 4 groups of 8 animals. Each group received 200mg/kg gentamicin (G) i.m., or 300 mg/kg vancomycin (V) i.v., or an association of 200 mg/kg gentamicin + 300 mg/kg vancomycin (i.m. and i.v., respectively), or 0.9% NaCl solution i.m. and i.v. (controls). To determine AAP, GGT, and NAG enzyme excretions, urine samples were taken over 24-h periods before and after the start of the experiment. A single renal cortical sample was obtained at necropsy for quantitation of antibiotic levels. No significant modifications of urinary excretions of creatinine and enzymuria were noted during the 24-h period before each drug administration or in controls. AAP, GGT, and NAG excretions were significantly increased after G and G + V injections (p < 0.001), whereas only AAP and GGT were statistically higher in rats receiving V (p < 0.05). NAG elimination (mean +/- SD) was higher in G + V (16.0 +/- 0.2 IU/mmol creatinine/24 h; p < 0.001) than g (8.8 +/- 0.6) or V (1.7 +/- 0.2). Surprisingly, mean vancomycin cortical levels decreased in the combination (827 +/- 131 vs. 1964 +/- 23 micrograms/g for V alone; p < 0.001), whereas gentamicin concentration was unchanged (826 +/- 66 vs. 839 +/- 28 micrograms/g for G alone). Determination of enzymuria allowed the nephrotoxicity of the antibiotics to be graded in the following order: vancomycin + gentamicin > gentamicin > vancomycin.

Virulence factors are released from Pseudomonas aeruginosa in association with membrane vesicles during normal growth and exposure to gentamicin: a novel mechanism of enzyme secretion

Pseudomonas aeruginosa blebs-off membrane vesicles (MVs) into culture medium during normal growth. Release of these vesicles increased approximately threefold after exposure of the organism to four times the MIC of gentamicin. Natural and gentamicin-induced membrane vesicles (n-MVs and g-MVs and g-MVs, respectively) were isolated by filtration and differential centrifugation, and several of their biological activities were characterized. Electron microscopy of both n-MVs and g-MVs revealed that they were spherical bilayer MVs with a diameter of 50 to 150 nm. Immunoelectron microscopy and Western blot (immunoblot) analysis of the vesicles demonstrated the presence of B-band lipopolysaccharide (LPS), with a slightly higher proportion of B-band LPS in g-MVs than in n-MVs. A-band LPS was occasionally detected in g-MVs but not in n-MVs. In addition to LPS, several enzymes, such as phospholipase C, protease, hemolysin, and alkaline phosphatase, which are known to contribute to the pathogenicity of Pseudomonas infections were found to be present in both vesicle types. Both types of vesicles contained DNA, with a significantly higher content in g-MVs. These vesicles could thus play an important role in genetic transformation and disease by serving as a transport vehicle for DNA and virulence factors and are presumably involved in septic shock.

Antioxidants attenuate endotoxin-gentamicin induced acute renal failure in rats

The synergistic mechanism by which endotoxin enhances the nephrotoxic potential of gentamicin is unknown. In this study, we attempted to shed light on this mechanism by injecting rats with endotoxin plus gentamicin. Renal injury was assessed by measuring creatinine, inulin and PAH clearance, NADH levels and electrolyte reabsorption, for 24 hr following this injection. Gentamicin alone (20 mg/100 g) induced no renal injury, while endotoxin without gentamicin (0.075 mg/100 g) induced mild injury. However, endotoxin plus gentamicin resulted in acute renal failure. In an attempt to halt the progressive renal dysfunction, the antioxidants NAO (5 mg/100 g), Vitamin E (0.2 mg/100 g per day) and dimethylthiourea (DMTU-50 mg/100 g) were administered, or early endotoxin tolerance was induced before injecting the rats with endotoxin plus gentamicin. The reduction in renal function was markedly slower in rats administered with antioxidants compared with untreated rats. Similar results were obtained with endotoxin tolerance. These data suggest that NAO, vitamin E, DMTU and endotoxin tolerance are potentially beneficial in arresting progressive renal damage associated with endotoxin plus gentamicin.

Glycopeptides and nephrotoxicity

Infections due to Gram-positive bacteria have become an increasing problem in the ICU. Furthermore, multidrug resistance among Gram-positive pathogens is increasingly recognized. Empirical therapy with antibiotic regimens that are effective against Gram-positive pathogens is often required in the ICU. Many critically ill patients in the ICU have multiorgan system failure, including acute renal failure, which further impedes optimal antimicrobial therapy. In this communication, the use of glycopeptides in the ICU is briefly reviewed, and the occurrence of associated nephrotoxicity during therapy with vancomycin or teicoplanin, alone or in combination with an aminoglycoside, is examined. Finally, existing recommendations regarding the dose regimens of these agents in patients with renal impairment are evaluated, and guide-lines for optimizing glycopeptide therapy through improved pharmacokinetic monitoring are presented.

Teicoplanin: a well-tolerated and easily administered alternative to vancomycin for gram-positive infections in intensive care patients

A prospective, randomized multicentre study was conducted in order to evaluate the potentially superior tolerability profile of teicoplanin plus netilmicin compared with vancomycin plus netilmicin in patients in ICUs. We considered that these glycopeptides have been shown to have comparable efficacy and that comparative tolerability is of paramount importance, particularly in severely ill patients. A total of 56 patients were enrolled into the study (36 males and 20 females). Twenty-four patients were included in the teicoplanin plus netilmicin group (15 males, 9 females: mean age 56.8 years). The mean simplified acute physiological score (SAPS) was 9.4 (range 4-20). Thirty-two patients were randomized to receive vancomycin plus netilmicin (21 males, 11 females; mean age 56.4 years). The mean SAPS was 9.3 (range 2-16). Septicaemia was the most common infection (14 cases in each group). Most infections were caused by Staphylococcus aureus or coagulase-negative staphylococci. The mean daily doses were: for teicoplanin, 457 mg (6.7 mg/kg); for vancomycin, 1678 mg (24.4 mg/kg); and for netilmicin 263.3 mg (3.9 mg/kg) in the teicoplanin group and 248 mg (3.8 mg/kg) in the vancomycin group. The trough levels of teicoplanin in the serum remained mostly between 7 and 10 mg/l, while more fluctuation was seen in patients receiving vancomycin. The mean trough levels of netilmicin in the serum were 1.2 (SD 0.9) mg/l in the teicoplanin group, compared with 1.7 (SD 1.4) mg/l in the vancomycin group (NS: p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ceftriaxone protects against tobramycin nephrotoxicity

The effect of ceftriaxone on tobramycin-induced nephrotoxicity was investigated. Female Sprague-Dawley rats were treated during 4 and 10 days with saline (NaCl, 0.9%), ceftriaxone at a dose of 100 mg/kg of body weight/12 h subcutaneously, tobramycin at doses of 40 and 60 mg/kg/12 h intraperitoneally, or the combination ceftriaxone-tobramycin. Creatinine levels in serum were significantly higher in animals treated with tobramycin alone given at 60 mg/kg/12 h during 10 days, compared with control animals (P < 0.01) or animals receiving the combination tobramycin-ceftriaxone (P < 0.01). After 10 days of treatment, ceftriaxone did not accumulate in renal tissue but did reduce the renal intracortical accumulation of tobramycin (P < 0.05). Tobramycin given alone at either 40 or 60 mg/kg/12 h induced a significant inhibition of sphingomyelinase activity compared with control animals (P < 0.05). However, this enzyme activity was significantly less inhibited when tobramycin was injected in combination with ceftriaxone (P < 0.05). Ceftriaxone alone had no effect on the activity of this enzyme. The [3H]thymidine incorporation into the DNA of renal cortex was also significantly lower in animals treated with tobramycin-ceftriaxone compared with animals receiving tobramycin alone (P < 0.05). The 24-h urinary excretion of beta-galactosidase was significantly reduced in animals treated with the combination tobramycin-ceftriaxone compared with the administration of tobramycin alone at 40 and 60 mg/kg/12 h after 5 and 10 days (P < 0.05). Histologically, ceftriazone induced very few cellular alterations and reduced considerably the presence of typical signs of tobramycin nephrotoxicity. This investigation demonstrated that ceftriaxone protects animals against tobramycin-induced nephrotoxicity.

Increased renal uptake of gentamicin in endotoxemic rats receiving concomitant thromboxane A2 antagonist therapy

This report describes the effects of endotoxin and a thromboxane receptor antagonist, L-655,240, on kidney function and the intrarenal pharmacokinetics of aminoglycosides. The rationale for these studies was that thromboxane antagonists may eventually be used in combination with aminoglycosides in patients with gram-negative sepsis and endotoxemia. As aminoglycosides are nephrotoxic and endotoxin has already been shown to increase the renal uptake of gentamicin, we investigated the possibility that thromboxane antagonists might interfere with the nephrotoxic potential of both substances. A decrease in the volume of distribution and an increase in the intracortical concentration of gentamicin were observed in animals given endotoxin. Compared with animals given endotoxin alone, those which received endotoxin plus L-655,240 had significant accumulation of gentamicin in the renal cortex and medulla, as determined by the area under the concentration-time curve, and a significant reduction in the total clearance of the antibiotic (P < 0.05). This difference in uptake could not be attributed to hypotension or changes in the glomerular filtration rate or renal plasma flow. L-655,240 alone did not modify gentamicin pharmacokinetics but did decrease p-aminohippuric acid secretion. Thromboxane antagonists in the context of endotoxemia increase intrarenal uptake of aminoglycosides. If these compounds are to be used as therapeutic agents when endotoxin is present, their influence on renal handling of nephrotoxic drugs needs to be considered. Multiple-dosing regimens deserve investigation.

Subcellular localization of tobramycin and vancomycin given alone and in combination in proximal tubular cells, determined by immunogold labeling

The subcellular localization of tobramycin and vancomycin in the renal cortices of rats was determined with ultrathin sections by immunogold labeling. Four groups of four rats each were treated for 10 days with saline (NaCl, 0.9%), tobramycin at dosages of 20 mg/kg of body weight per 12 h intraperitoneally, vancomycin at dosages of 25 mg/kg/12 h subcutaneously, or the combination tobramycin-vancomycin. On day 11, the animals were killed, and cubes of renal cortex were fixed overnight in phosphate-buffered glutaraldehyde (0.5%), dehydrated in ethanol, and embedded in Araldite 502 resin. Ultrathin sections were made and incubated with sheep antitobramycin antibody followed by protein A-gold (15-nm diameter) complex or rabbit antivancomycin antibody followed by gold (30-nm diameter)-labeled goat anti-rabbit antibody. For the double labeling, incubations were made on opposite sides of the grid. Tobramycin was detected over the lysosomes of proximal tubular cells, but the labeling was concentrated into small areas in the matrix of the lysosomes. Vancomycin was seen over the lysosomes of proximal tubular cells and was distributed uniformly throughout the matrix of the lysosomes. In rats treated with tobramycin-vancomycin, both drugs were still detected in lysosomes of proximal tubular cells. It is concluded that tobramycin and vancomycin accumulate in lysosomes of proximal tubular cells throughout 10 days of treatment and that vancomycin has no effect on the subcellular distribution of tobramycin.

Antibiotic-induced release of endotoxin in chronically bacteriuric patients

A novel in vivo model for the study of antibiotic-induced release of endotoxin from gram-negative bacteria is described. The model uses the chronically colonized urinary tracts of patients whose spinal cords have been injured. At baseline, the organisms were present in the range of 1 x 10(3) to 2 x 10(7) CFU/ml, and the concentration of endotoxin ranged from 2 x 10(-1) to 1 x 10(3) ng/ml in 44 studies. In 10 control studies, the concentration of endotoxin and the numbers of viable gram-negative bacteria over time changed by an average of less than 0.15 log10 units from the baseline values. At 2 h after antibiotic administration, the average decrease in CFU was 0.93 log10 units, and because antibiotics cause the release of endotoxin, an average increase in endotoxin concentration of 0.59 log10 units was noted in 21 studies with susceptible bacteria. Similar changes in response to antibiotic exposure were seen in studies with susceptible Pseudomonas bacteria in comparison with those seen in studies with susceptible members of the family Enterobacteriaceae. These results provide evidence that this novel model may be useful for comparing the effects of antibiotics with different modes of action, both as single agents and in combination, on the concentration of endotoxin in relation to changes in the numbers of bacteria, under conditions of bacterial replication and antibiotic exposure more closely resembling those found in vivo than is possible in other models.

Endotoxin-tobramycin additive toxicity on renal proximal tubular cells in culture

Aminoglycoside-induced renal damage is enhanced in animals with Escherichia coli pyelonephritis. Bacterial endotoxin is liberated during antibiotic therapy. The toxic effect of endotoxin and tobramycin, alone or in combination, was investigated in primary cultures of rabbit proximal tubular cells grown to confluence in serum-free medium. Sodium-dependent uptakes of Pi and alpha-methylglucopyranoside (MGP) and enzymatic activities (lactate dehydrogenase [LDH] released as a marker of cell necrosis and gamma-glutamyltransferase [GGT] and N-acetyl-beta-D-glucosaminidase [NAG] present in the homogenate as markers of brush border membrane and lysosome integrity) were measured. Cells were exposed to (i) endotoxin (20 mg/liter), tobramycin (1 mM), or endotoxin plus tobramycin for 48 h, or (ii) endotoxin (100 mg/liter), tobramycin (4 mM), or endotoxin plus tobramycin for 72 h. Endotoxin alone did not alter Pi uptake, but tobramycin inhibited Pi uptake through a decrease in Vmax. The effect was not enhanced by the combination of endotoxin and tobramycin. Endotoxin and tobramycin alone exerted no significant effect upon MGP uptake, but strong inhibition of the Vmax was observed after exposure to a combination of endotoxin plus tobramycin, without alteration of the Km. Endotoxin decreased residual GGT activity in the cell homogenate. Tobramycin increased LDH release in the medium and NAG activity in the homogenate. Endotoxin plus tobramycin resulted in an additive effect upon LDH and NAG activities. In conclusion, by disturbing apical membrane integrity, endotoxin increased tobramycin toxicity in vitro in the absence of serum hormonal mediator.

Pathogenic factors in aminoglycoside-induced nephrotoxicity

Aminoglycoside antibiotics play an integral role in antimicrobial chemotherapy. Unfortunately, these drugs are known to cause nephrotoxicity in man and experimental animals. In fact, the incidence of renal dysfunction during the course of clinical treatment with aminoglycoside antibiotics is approximately 10%. Over the past two decades the elucidation of the pathogenesis of aminoglycoside-induced nephrotoxicity has been the subject of numerous investigations. This review describes the recent theories postulated to play a role in the pathogenesis of antibiotic-induced renal damage. In particular, the importance of amino-glycoside levels in the renal cortex or at the membrane binding site is examined in detail. The relevance of antibiotic tissue levels is reflected in the ability of other drugs to modify nephrotoxicity through an alteration in renal aminoglycoside content. The role of factors including age and diet in drug-induced nephrotoxicity is described. In clinical practice, aminoglycoside antibiotics may often be with other agents. The influence of aminoglycoside interaction with other drugs including vancomycin, cephalosporins and cytotoxic drugs is examined in the light of reports that nephrotoxicity is potentiated in these situations. In addition, this review focuses on the role of infection (pyelonephritis and septicemia) and bacterial endotoxin as pathogenic factors involved in aminoglycoside nephrotoxicity. Both the direct influence of endotoxin and the indirect effects of vasoactive mediators and inflammatory processes will be discussed. A multiplicity of factors is involved in the pathogenesis of aminoglycoside-induced nephrotoxicity and these are further amplified in the presence of infection.