Tobramycin Systemic Absorption in Lung Transplant Recipients Treated With Inhaled Tobramycin: A Cohort Study.

Inhaled tobramycin treatment has been associated with nephrotoxicity in some case reports, but limited data are available about serum levels and its possible systemic absorption in lung transplant recipients (LTR). We conducted a single-center, observational and retrospective study of all adult (>18 years old) LTR treated with inhaled tobramycin for at least 3 days between June 2019 and February 2022. Trough serum levels were collected and >2 µg/mL was considered a high drug level. The primary outcome assessed the presence of detectable trough levels, while the secondary outcome focused on the occurrence of acute kidney injury (AKI) in individuals with detectable trough levels. Thirty-four patients, with a median age of 60 years, were enrolled. The primary indications for treatment were donor bronchial aspirate bacterial isolation (18 patients) and tracheobronchitis (15 patients). In total, 28 patients (82%) exhibited detectable serum levels, with 9 (26%) presenting high levels (>2 µg/mL). Furthermore, 9 patients (26%) developed acute kidney injury during the treatment course. Median trough tobramycin levels were significantly elevated in invasively mechanically ventilated patients compared to non-ventilated individuals (2.5 µg/mL vs. 0.48 µg/mL) (p < 0.001). Inhaled tobramycin administration in LTRs, particularly in those requiring invasive mechanical ventilation, may result in substantial systemic absorption.

A prospective phase IIA multicenter double-blinded randomized placebo-controlled clinical trial evaluating the efficacy and safety of inhaled Tobramycin in patients with ventilator-associated pneumonia (iToVAP).

OBJECTIVE: Treatment of ventilated pneumonia is often unsuccessful, even when patients are treated according to current guidelines. Therefore, we aimed to investigate the efficacy of the adjunctive inhaled Tobramycin in patients with pneumonia caused by Gram-negative pathogens in addition to the standard systemic treatment. DESIGN: Prospective, multicenter, double-blinded, randomized, placebo-controlled clinical trial. SETTING: 26 patients in medical and surgical ICUs. PATIENTS: Patients with ventilator-associated pneumonia caused by Gram-negative pathogens. MEASUREMENT AND MAIN RESULTS: Fourteen patients were assigned to the Tobramycin Inhal group and 12 patients to the control group. The microbiological eradication of the Gram-negative pathogens was significantly higher in the intervention group than in the control group (p < 0.001). The probability of eradication was 100% in the intervention group [95% Confidence Interval: 0.78-1.0] and 25% in the control group [95% CI: 0.09-0.53]. The increased eradication frequency was not associated with increased patient survival. CONCLUSION: Inhaled aerosolized Tobramycin demonstrated clinically meaningful efficacy in patients with Gram-negative ventilator-associated pneumonia. The probability of eradication in the intervention group was 100%. However, the successful eradication was not associated with a reduction in systemic anti-infective therapy, a shorter ICU stay, or even a survival benefit. In the presence of multidrug-resistant Gram-negative pathogens that are sensitive only to colistin and/or aminoglycosides, supplemental inhaled therapy with nebulizers suitable for this purpose should be considered in addition to systemic antibiotic therapy.

Acute Kidney Injury because of Implanted Tobramycin Pellets: A Case Report.

CASE: A 50-year-old healthy man with normal kidney function underwent surgery for fracture-related infection. Unfortunately, the patient received 2.5 times the intended dose of tobramycin pellets in the medullary cavity and developed acute kidney failure. Given the intraosseous administration of tobramycin, the drug displayed an absorption-dependent pharmacokinetics and multiple treatments with hemodialysis were needed. However, the patient had a complete recovery, and the kidney function remained normal at the 2-year follow-up. CONCLUSION: Tobramycin pellets are nephrotoxic in supratherapeutic doses; however, it was reversible in this case. Owing to the intraosseous administration, multiple treatments with hemodialysis were required.

Exploration of the relationship between cumulative exposure to tobramycin and ototoxicity in patients with cystic fibrosis.

BACKGROUND: Aminoglycosides (AGs), such as tobramycin, are essential antibiotics in the management of pulmonary infections in patients with cystic fibrosis (CF). They induce ototoxicity without the relationship being clearly described in the literature. Our aim is to propose a mathematical and statistical model describing the relationship between the estimated cumulative exposure (Area Under the Curve, AUC) to tobramycin and ototoxicity with audiogram interpretation in young patients with CF. METHODS: Cumulative AUCs were estimated for each course of tobramycin, for the 106 individuals with CF (between 4 and 22 years of age) enrolled in this retrospective study (35 who had received IV tobramycin, 71 controls). Mean hearing loss was calculated for each audiogram and a statistical model was developed to predict hearing loss. RESULTS: The model confirms a significant relationship between cumulative tobramycin exposure and changes in hearing acuity: Meanhearingloss=2.7+(3×10-5)×AUC_tobramycin+individual_susceptibility However, the ototoxic effect is not clinically perceptible (mean hearing loss: 3.8 dB). The impact of AUC on hearing loss is minor in these subjects who received a limited number of courses of tobramycin (median: 5 courses). CONCLUSION: A significant relationship between cumulative exposure to tobramycin and ototoxicity was demonstrated. Individual treatment susceptibility should not be overlooked. As ototoxicity is not clinically perceptible in the study subjects, hearing tests should be continued during adulthood to provide individualized medical guidance and to obtain a lifetime analysis of the relationship between exposure and hearing loss.

Tobramycin and antiglaucoma agents as increasing culprits of periorbital allergic contact dermatitis from topical ophthalmic medications: A 24-year study from Turkey.

BACKGROUND: Allergic contact dermatitis (ACD) from topical ophthalmic medications (TOMs) poses an additional disease burden to patients who already suffer from eye problems. OBJECTIVES: To investigate the epidemiological/clinical profile of patients with periorbital ACD from TOMs in Turkey. PATIENTS AND METHODS: This was a retrospective, cross-sectional, single tertiary centre study based on files of 75 patch tested patients with suspected periorbital ACD from TOMs among a total of 2801 consecutively patch tested patients with suspected ACD of any origin between 1996 and 2019. RESULTS: Periorbital ACD was diagnosed in 25 of 75 (33.3%) patients (female:male = 1.8:1; age range: 6-85 years) with suspected ACD from TOMs showing an overall prevalence of 0.9% (25/2801) among the whole patch test population. Atopy was not present. Tobramycin-containing TOMs were the most frequent culprits, followed by antiglaucoma preparations. Their frequency increased, whereas no new cases of neomycin-induced ACD were observed after 2011. Positivities with thimerosal were of unknown clinical relevance, while benzalkonium chloride (BAC) caused ACD in two patients. The diagnosis would be missed in each 20% of patients without performing day (D) 4 and D7 readings and strip-patch testing. Ten culprits were identified only by testing with patients' own TOMs in eight (32%) patients. CONCLUSIONS: Aminoglycosides, particularly tobramycin, were the leading cause of ACD from TOMs. The frequency of ACD from tobramycin and antiglaucoma medications increased after 2011. BAC was a rare but important allergen. Additional D4 and D7 readings, strip-patch testing, and testing with patients' own TOMs seem essential when patch testing with eye medications.

Effects of long-term tobramycin inhalation solution (TIS) once daily on exacerbation rate in patients with non-cystic fibrosis bronchiectasis.

BACKGROUND: Use of long-term tobramycin inhalation solution (TIS) has been shown beneficial in cystic fibrosis (CF) and earlier findings also suggest a benefit in non-CF bronchiectasis. We investigated the efficacy and safety of maintenance TIS once daily (OD) in frequent exacerbating bronchiectasis patients chronically infected by different pathogens sensitive for tobramycin. OBJECTIVE: The primary outcome was the frequency of exacerbations during the 12-month study period. Secondary outcomes were time to first exacerbation, change in lung function and quality of life (QoL), bacterial analysis and safety. MATERIALS/PATIENTS: IN THIS MULTICENTER RCT PATIENTS AGED ≥ 18-YEAR-OLD WERE INCLUDED WITH CONFIRMED BRONCHIECTASIS AND ≥ 2 EXACERBATIONS IN THE PRECEDING YEAR. PATIENTS WERE ASSIGNED (1:1) TO RECEIVE TIS OR PLACEBO OD FOR 1-YEAR.: RESULTS: 58 patients were included of which 52 were analyzed in the mITT analysis. TIS reduced exacerbation frequency with a RR of 0.74 (95% CI 0.49-1.14) (p = 0.15). Within the TIS population a decrease in number of exacerbations was found (2; p = 0.00), which was also seen in the placebo-treated patients (1.5; p = 0.00). In the TIS-treated patients the QoL improved (LRTI-VAS p = 0.02 Leicester Cough p = 0.02) without additional safety concerns. No differences were found for the other secondary outcomes. CONCLUSION: Long-term TIS OD is a safe treatment modality and showed a non-significant reduced exacerbation frequency of 0.74 as compared to placebo in bronchiectasis patients chronically infected by tobramycin sensitive pathogens. TIS OD may be a potential therapeutic strategy in selected patients with bronchiectasis suffering from a high burden of disease. TRAIL REGISTRATION NUMBER: The BATTLE study was registered at Clinical trials.gov number: NCT02657473 . Date: 13 august 2016.

Acute kidney injury in cystic fibrosis patients treated with intravenous colistimethate sodium or tobramycin.

OBJECTIVES: Colistimethate sodium and tobramycin are important systemic antibiotics for treatment of cystic fibrosis (CF) pulmonary exacerbations but can induce acute kidney injury (AKI). We characterize the rate of AKI in CF patients treated with systemic colistimethate sodium compared with tobramycin. METHODS: This single-centre, retrospective cohort study included hospitalized CF patients treated with IV colistimethate sodium or tobramycin. The primary outcome was AKI defined using the RIFLE criteria. Multivariate logistic regression using a mixed model was performed to identify variables that were independently associated with AKI. RESULTS: Overall, 156 patients representing 507 care encounters were included. The OR of AKI was not increased with IV colistimethate sodium relative to IV tobramycin after adjusting for other potential predictor variables (aOR 1.00; 95% CI 0.16-6.03). The frequency of AKI was 9.5% across all encounters, 6.9% with IV colistimethate sodium and 9.9% with IV tobramycin, with RIFLE category R (risk) being the most common stage, accounting for 4.2% of encounters with IV colistimethate sodium and 9.2% with IV tobramycin. The concomitant use of another nephrotoxin (aOR 2.51; 95% CI 1.27-4.95) or the combination of vancomycin and piperacillin/tazobactam (aOR 5.95; 95% CI 2.05-17.3) were both associated with increased odds of AKI. CONCLUSIONS: Systemic treatment with colistimethate sodium or tobramycin in the CF patient population is associated with a similar rate of nephrotoxicity. However, clinicians should be mindful of the increased risk for AKI in patients treated with either IV colistimethate sodium or IV tobramycin when used concurrently with other nephrotoxic agents, particularly the combination of vancomycin and piperacillin/tazobactam.

Tobramycin safety and efficacy review article.

Pseudomonas aeruginosa is a common respiratory pathogen found in patients with cystic fibrosis (CF), contributing to increased hospitalization, more rapid progression of CF lung disease, and increased risk of death. Guidelines recommend early therapy using tobramycin inhaled solution (TIS) or inhaled powder (TIP). Both TIS and TIP treatment regimens have demonstrated positive clinical outcomes in efficacy and safety, including improvements in FEV1, decreased sputum P. aeruginosa density, decreased rates in antipseudomonal antibiotic use, and reduced rates of hospitalizations due to respiratory events. In a comparison of patient preference for TIS versus TIP, a patient survey cited time savings and convenience as preferences for TIP. However, both TIP and TIS offer advantages that may benefit patients and increase treatment adherence depending on patient circumstances. TIS may be suitable for younger patients at home where parents and caregivers may better control proper administration, older individuals, and those with low FEV1. Dry powder inhalers are suitable when patients have less time to commit to their self-care (eg, patients who work, are remotely located, return home late, or are on vacation), and can reduce the patient treatment burden compared with nebulized delivery. In this expert review, we summarize the available data on tobramycin regarding its molecular characteristics, mechanism of action, and efficacy and safety for the treatment of acute and chronic P. aeruginosa infection.

The use of tobramycin for Pseudomonas aeruginosa: a review.

INTRODUCTION: Pseudomonas aeruginosa is a common respiratory pathogen that contributes to chronic pulmonary infection in individuals with cystic fibrosis. Guidelines recommend early intervention upon positive P. aeruginosa culture. Tobramycin has in vitro activity against Gram-negative bacteria, including P. aeruginosa, and TOBI Podhaler is indicated for the management of individuals with cystic fibrosis with P. aeruginosa infection. The dry powder inhaler formulation decreases the time required for treatment compared with nebulized solution and therefore may improve quality of life and adherence, which have a positive impact on disease progression. AREAS COVERED: In this review, we discuss the safety and efficacy of tobramycin inhaled powder and provide insights into appropriate individuals who might benefit from a dry powder inhaler, keeping in mind that patient preference is an important consideration for therapy selection. EXPERT OPINION: Providing a less burdensome alternative to delivering inhaled antibiotics that is more portable with a significantly shorter administration time may help improve adherence, and therefore improve outcomes. Continued development of new antibiotics to add to current regimens for eradication and control of airway microbiology, combined with more efficient delivery systems such as tobramycin inhaled powder, will help evolve the treatment of patients with CF.

Timely explantation of tobramycin-impregnated beads and bone cement to avoid haemodialysis in a patient with worsening renal failure.

A male patient with right total knee arthroplasty complicated by prosthetic joint infection on intravenous antimicrobials developed an acute kidney injury (AKI) with creatinine up to 7.3 mg/dL ('normal' range (0.5-1.2 mg/dL)) after hardware removal and tobramycin loaded polymethylmethacrylate beads and spacer placement. The AKI was initially attributed to intravenous vancomycin. Despite discontinuing vancomycin, the AKI worsened. A tobramycin level was collected and resulted at 5.5 µg/mL. Due to high suspicion for aminoglycoside-induced renal toxicity and to prevent haemodialysis, the antibiotic cement spacer with tobramycin-impregnated beads was removed. After the removal, tobramycin level rapidly decreased and renal functions improved. AKI is an increasingly recognised complication related to antibiotic-loaded bone cement (ALBC) due to the systemic absorption of antibiotics. With this case we highlight the early recognition of ALBC-induced renal toxicity necessitating explantation of ALBC and beads in order to prevent haemodialysis and emphasise monitoring aminoglycoside levels in the early postoperative period.

Anti-Glomerular Basement Membrane Nephritis Potentially Induced by Nebulized Tobramycin Inhalation.

Objective: To describe a case of anti-glomerular basement membrane (GBM) nephritis that occurred shortly after initiation of nebulized tobramycin (TOB) therapy using intravenous solution, suggesting an association with the inhalation therapy and the disease onset. Background: With the emergence of antimicrobial resistance, clinical importance of aminoglycosides that usually remain susceptibility against gram-negative organisms is increasingly acknowledged. Despite the growing number of evidence supporting the effectiveness of aminoglycoside inhalation therapy for respiratory tract infections, its clinical application has yet to be widely approved by Japanese health insurance. Case Presentation: A 79-year-old Japanese woman had developed amyotrophic lateral sclerosis and experienced recurrent pneumonia mainly caused by Pseudomonas aeruginosa, which required monthly treatments with broad-spectrum antibiotics. Owing to the limited approval, we had no choice but to use intravenous TOB solution for inhalation therapy as an off-label use under an endorsement of the Institutional Review Board of the hospital. Although the repeated pneumonia subsided, the patient subsequently needed immunosuppressive therapy along with plasma exchanges for the treatment of anti-GBM nephritis. Conclusion: Although this off-label use of intravenous solutions is common in both clinical and research purposes, our case raised an issue that its safety needs to be re-evaluated.

Tobramycin and vestibulotoxicity: retrospective analysis of four cases.

Over a course of 7 months, four patients developed vestibulotoxicity after treatment with intravenous tobramycin. Since vestibulotoxicity is a serious adverse effect which can be irreversible, an investigation was undertaken to determine if there was a cause for the toxicity and whether the quality of care had been inadequate. In this period, 26 patients with cystic fibrosis were treated with tobramycin according to valid guidelines, of which four experienced acute dizziness which disrupted their daily activities. Two patients experienced irreversible bilateral vestibular hypofunction and two unilateral loss of the right labyrinth, with decreasing dizziness over time. No apparent cause for the vestibulotoxicity was found in these four patients and the simultaneous occurrence was not due to a lack in quality of care. Symptoms of dizziness and balance disorders should be recognised by patients and caretakers at an early stage so additional diagnostics can be done to prevent further deterioration.

Combined Treatment of 6-Gingerol Analog and Tobramycin for Inhibiting Pseudomonas aeruginosa Infections.

Pseudomonas aeruginosa is a ubiquitous human pathogen that causes severe infections. Although antibiotics, such as tobramycin, are currently used for infection therapy, their antibacterial activity has resulted in the emergence of multiple antibiotic-resistant bacteria. The 6-gingerol analog, a structural derivative of the main component of ginger, is a quorum sensing (QS) inhibitor. However, it has a lower biofilm inhibitory activity than antibiotics and the possibility to cause toxicity in humans. Therefore, novel and more effective approaches for decreasing dosing concentration and increasing biofilm inhibitory activity are required to alleviate P. aeruginosa infections. In this study, a 6-gingerol analog was combined with tobramycin to treat P. aeruginosa infections. The combined treatment of 6-gingerol analog and tobramycin showed strong inhibitory activities on biofilm formation and the production of QS-related virulence factors of P. aeruginosa compared to single treatments. Furthermore, the combined treatment alleviated the infectivity of P. aeruginosa in an insect model using Tenebrio molitor larvae without inducing any cytotoxic effects in human lung epithelial cells. The 6-gingerol analog showed these inhibitory activities at much lower concentrations when used in combination with tobramycin. Adjuvant effects were observed through increased QS-disrupting processes rather than through antibacterial action. In particular, improved RhlR inactivation by this combination is a possible target for therapeutic development in LasR-independent chronic infections. Therefore, the combined treatment of 6-gingerol analog and tobramycin may be considered an effective method for treating P. aeruginosa infections. IMPORTANCE Pseudomonas aeruginosa is a pathogen that causes various infectious diseases through quorum-sensing regulation. Although antibiotics are mainly used to treat P. aeruginosa infections, they cause the emergence of resistant bacteria in humans. To compensate for the disadvantages of antibiotics and increase their effectiveness, natural products were used in combination with antibiotics in this study. We discovered that combined treatment with 6-gingerol analog from naturally-derived ginger substances and tobramycin resulted in more effective reductions of biofilm formation and virulence factor production in P. aeruginosa than single treatments. Our findings support the notion that when 6-gingerol analog is combined with tobramycin, the effects of the analog can be exerted at much lower concentrations. Furthermore, its improved LasR-independent RhlR inactivation may serve as a key target for therapeutic development in chronic infections. Therefore, the combined treatment of 6-gingerol analog and tobramycin is suggested as a novel alternative for treating P. aeruginosa infections.

Pharmacokinetic modelling to predict risk of ototoxicity with intravenous tobramycin treatment in cystic fibrosis.

INTRODUCTION: Further optimization of therapeutic drug monitoring (TDM) for aminoglycosides (AGs) is urgently needed, especially in special populations such as those with cystic fibrosis (CF), >50% of whom develop ototoxicity if treated with multiple courses of IV AGs. This study aimed to empirically test a pharmacokinetic (PK) model using Bayesian estimation of drug exposure in the deeper body tissues to determine feasibility for prediction of ototoxicity. MATERIALS AND METHODS: IV doses (n = 3645) of tobramycin and vancomycin were documented with precise timing from 38 patients with CF (aged 8-21 years), including total doses given and total exposure (cumulative AUC). Concentration results were obtained at 3 and 10 h for the central (C1) compartment. These variables were used in Bayesian estimation to predict trough levels in the secondary tissue compartments (C2 trough) and maximum concentrations (C2max). The C1 and C2 measures were then correlated with hearing levels in the extended high-frequency range. RESULTS: Patients with more severe hearing loss were older and had a higher number of tobramycin C2max concentrations >2 mg/L than patients with normal or lesser degrees of hearing loss. These two factors together significantly predicted average high-frequency hearing level (r = 0.618, P < 0.001). Traditional metrics such as C1 trough concentrations were not predictive. The relative risk for hearing loss was 5.8 times greater with six or more tobramycin courses that exceeded C2max concentrations of 3 mg/L or higher, with sensitivity of 83% and specificity of 86%. CONCLUSIONS: Advanced PK model-informed analysis predicted ototoxicity risk in patients with CF treated with tobramycin and demonstrated high test prediction.

Ototoxicity in cystic fibrosis patients receiving intravenous tobramycin for acute pulmonary exacerbation: Ototoxicity following tobramycin treatment.

Aminoglycosides are commonly used to treat infections in CF patients and are highly ototoxic. The incidence of tobramycin-induced hearing loss, tinnitus, vertigo or dizziness (ototoxicity) varies widely from 0 to 56% secondary to variation in patient enrollment, dosing, audiometry, and ototoxic criteria. The aim of this study is to determine the incidence of ototoxicity after one course of once-daily IV tobramycin in CF patients. Adult CF patients with acute pulmonary exacerbations were enrolled on IV tobramycin (10 mg/kg/d, ≥10 days). Pure-tone audiometry was performed for standard and extended high frequencies in the sensitive range for ototoxicity (SRO). American-Speech-Language-Hearing-Association cochleotoxicity criteria were applied. Distortion product otoacoustic emissions (DPOAE) and the words-in-noise-test (WINT) were assessed. Tinnitus Functional Index (TFI) and Vertigo Symptoms Scale (VSS) were used. Eighteen CF patients, mean age 31.1 (18-59), were enrolled. The incidence of cochleotoxic change from baseline at 2 and 4 weeks post-treatment was 89% and 93%. For DPOAE, a measure of outer hair-cell function, the incidence of ≥5 dB decrease was 82% and 80%. For WINT, a measure of word recognition, the incidence of ≥10% decrease was 17% and 40%. For TFI, the incidence of ≥10pt increase was 12% and 8%, and for VSS, the incidence of ≥6pt increase was 0% and 8%. One course of IV tobramycin was sufficient to cause hearing loss and other ototoxic symptoms four weeks after treatment ended. Audiometric measures were more sensitive to ototoxic change than TFI & VSS. Age and duration of tobramycin treatment were not obvious factors for predicting ototoxicity.

Results of Tobramycin Inhalation Therapy in Patients with Noncystic Fibrosis Bronchiectasis with Pseudomonas aeruginosa Colonization: Real Life Management.

Background: Inhaled antibiotics for treating bronchiectasis have been investigated in the cystic fibrosis population since 1981 and long-term clinical benefits have been reported. However, studies on noncystic fibrosis bronchiectasis (NCFB) have only been performed more recently. Owing to limited evidence, inhaled antibiotics are not currently approved for treating NCFB by the U.S. Food and Drug Administration and the European Medicines Agency. The aim of this study was to evaluate the efficacy and safety of tobramycin inhalation therapy in patients with bronchiectasis with Pseudomonas aeruginosa (PA) colonization. Methods: In this retrospective cross-sectional study, NCFB patients who were Pseudomonas positive on three consecutive cultures 1 month apart and receiving tobramycin inhalation therapy were evaluated. Evaluation of the following parameters was done in this study: age, gender, smoking history, symptoms, pulmonary function test results, sputum culture results, tobramycin treatment duration, side effects of tobramycin and response evaluation, and hospital admissions before and after treatment. Treatment with 300 mg tobramycin through nebulizer twice daily for 28 days on-off cycles for a total of 6 months was considered to be one treatment period. The approvals for the study were received by the local ethics committee and institutional review board. Results: Of the 27 patients, 21 patients completed the first period, 7 patients completed the second period, 4 patients completed the third period, and 1 patient completed the fourth period. Sputum culture was negative in 10 (47.6%) of the 21 patients who completed the first period. Decreased sputum purulence and quantity, dyspnea, and cough were observed during treatment. The frequency of hospitalizations before treatment was 1.24 ± 1.36, whereas after treatment, it decreased to 0.52 ± 0.91, this difference was statistically significant (p = 0.019). The most common side effect was increased dyspnea after nebulization in five patients. Conclusion: Tobramycin inhalation appears to be a well-tolerated treatment in patients with PA colonization with bronchiectasis. This treatment may decrease the hospitalization rates and improve the symptoms.

Prospective cohort study of ototoxicity in persons with cystic fibrosis following a single course of intravenous tobramycin.

INTRODUCTION: Aminoglycoside (AG) antibiotics, such as tobramycin, are known to be ototoxic but important clinically due to their bactericidal efficacy. Persons with cystic fibrosis (CF) are at risk for AG-induced ototoxicity due to the repeated use of intravenous (IV) tobramycin for the treatment of pulmonary exacerbations. While it is well-established that ototoxic hearing loss is highly prevalent in this clinical population, the progression of hearing loss over time remains unclear. Cumulative IV-AG dosing has been associated with a higher risk of ototoxic hearing loss, yet some individuals lose substantial hearing after a single IV-AG treatment, while others never seem to lose hearing. METHODS: 31 persons with CF (18 on IV tobramycin, 13 controls) were enrolled in an observational study. Pure-tone hearing thresholds (0.25-16 kHz) were measured at baseline (pre-treatment) and at follow-up for each subject. A hearing shift was determined using various metrics, and outcomes were compared to characterize changes in hearing bilaterally for both study groups. RESULTS: Comparison of pure-tone threshold shifts between baseline and follow-up audiograms following either a course of IV tobramycin (n = 18) or no intervening therapy (n = 13) demonstrated significant (p < 0.05) threshold shifts in all continuous metrics tested. CONCLUSION: A single course of IV tobramycin causes ototoxic hearing loss in some people with CF, which supports the need for routine ototoxicity monitoring and management in this clinical population. These findings also suggest that people with CF are a suitable population for clinical trials examining ototherapeutics in single IV-tobramycin treatment episodes.

Mode of bacterial killing affects the inflammatory response and associated organ dysfunctions in a porcine E. coli intensive care sepsis model.

BACKGROUND: Sepsis is often treated with penicillin-binding protein 3 (PBP-3) acting ß-lactam antibiotics, such as piperacillin-tazobactam, cefotaxime, and meropenem. They cause considerable bacterial structural changes and have in vitro been associated with an increased inflammatory response. In a clinically relevant large animal sepsis model, our primary aim was to investigate whether bacteria killed by a PBP-3-active antibiotic has a greater effect on the early inflammatory response and organ dysfunction compared with corresponding amounts of live or heat-killed bacteria. A secondary aim was to determine whether the addition of an aminoglycoside could mitigate the cefuroxime-induced response. METHOD: Killed or live Escherichia coli were administrated as a 3-h infusion to 16 healthy pigs in a prospective, randomized controlled interventional experimental study. Cefuroxime was chosen as the PBP-3-active antibiotic and tobramycin represented the aminoglycosides. The animals were randomized to receive (I) bacteria killed by cefuroxime, (II) live bacteria, (III) bacteria killed by heat, or (IV) bacteria killed by the combination of cefuroxime and tobramycin. Plasma endotoxin, tumor necrosis factor alpha, interleukin-6, interleukin-10, leukocytes, and organ function were recorded at the start of the experiment and then hourly for 6 h. RESULTS: Differences in dynamics of concentration over time between the four treatment groups were found for the three cytokines (p < 0.001). Animals receiving cefuroxime-killed bacteria demonstrated higher responses than those receiving live (p < 0.05) or heat-killed bacteria (p < 0.01). The addition of tobramycin reduced the cefuroxime-induced responses (p < 0.001). The cytokine responses were associated with leucocyte activation that was further associated with pulmonary dysfunction and increases in lactate (p < 0.01). CONCLUSIONS: In comparison with live or heat-killed bacteria, bacteria killed by a PBP-3-active antibiotic induced an increased inflammatory response that appears to be associated with deteriorated organ and cellular function. The addition of an aminoglycoside to the PBP-3-active antibiotic reduced that response.

Incidence of nephrotoxicity with prolonged aminoglycoside exposure in patients with cystic fibrosis.

Cystic fibrosis (CF) patients, with Pseudomonas aeruginosa infection, often require repeated aminoglycoside courses for the management of acute pulmonary exacerbations (APEs). Acute kidney injury (AKI) due to aminoglycosides has been reported; little data exist regarding long-term nephrotoxicity with repeated exposure. The objective of this study was to describe the incidence of acute and chronic nephrotoxicity due to cumulative intravenous (IV) aminoglycoside exposure. This is a retrospective, observational study of pediatric and adult CF patients admitted to an academic medical center between January 1, 2006 and October 1, 2018 for APE management. Patients were eligible for inclusion if they received at least five courses of an IV aminoglycoside for at least 7 days each. Cumulative weight-based aminoglycoside dose was reported in milligrams per kilogram. For each admission, baseline and highest serum creatinine were collected to assess the incidence of AKI. The baseline and final estimated glomerular filtration rate (eGFR) were calculated to assess long-term effects on renal function. Sixty-six patients, representing greater than 700 courses, were included in the final analysis. The median cumulative weight-based aminoglycoside dose was 1183 mg/kg of tobramycin or tobramycin equivalent. Twenty percent of courses resulted in AKI; 86% were Stage 1. A repeated measure multivariate model showed colistin, piperacillin/tazobactam, vancomycin, and age were significant AKI risk factors. There was no correlation between cumulative aminoglycoside dose and change in eGFR. AKI from IV aminoglycoside exposure occurred in 20% of courses. Cumulative exposure to IV aminoglycosides in APE management was not correlated with long-term renal dysfunction.

Elution Profiles of Synthetic CaSO4 Hemihydrate Beads Loaded with Vancomycin and Tobramycin.

BACKGROUNDS AND OBJECTIVES: The use of local antibiotic delivery vehicles is common in the management of biofilm-related infections as they provide high concentrations of local antibiotics while simultaneously avoiding complications from systemic toxicity. We present a 100% pure synthetic calcium sulfate hemi-hydrate mixed with 240 mg tobramycin and 500 mg vancomycin per 10 cc mixture for use in revision surgeries of periprosthetic joint infections (PJIs). The purified carrier demonstrates bioabsorbablity, promotion of bone growth, a physiologically favorable pH, and hydrophilicity. These unique properties may alleviate persistent postoperative wound drainage seen in patients with PJI. Our questions consist of two parts: (1) does the novel calcium sulfate carrier provide therapeutic concentrations of antibiotic locally that can kill biofilm related infections? (2) Are serum concentrations of antibiotic significant to cause concern for systemic toxicity? METHODS: To address these questions, we assayed the elution of antibiotic concentrations obtained from surgical drains and serum among 50 patients in the first 5 postoperative days. RESULTS: The elution of vancomycin and tobramycin was greatest on day 1 compared with those concentrations obtained on days 2, 3, 4, and 5; serum concentrations were largely undetectable. Our findings demonstrate that this calcium sulfate preparation provides therapeutic delivery of vancomycin and tobramycin locally at log 2-3 above the minimum inhibitory concentration (MIC), while avoiding toxic serum concentrations. CONCLUSIONS: When used in one-stage revision arthroplasties, the bioabsorbable, purified carrier delivers high concentrations of antibiotic while avoiding systemic toxicity.