We analyzed the efficacy and safety of aminoglycosides in a retrospective study of 415 patients with acute appendicitis and 277 patients with acute cholecystitis. The following variables increased the incidence of postoperative complications, defined as surgical site infection, recurrent intraabdominal infection, non-infectious post-operative complication, or death: age (p = 0.016 and 0.011), kidney disease (p = 0.019 and <0.001), and ASA Score (p < 0.001). The type of antibiotic therapy did not have a statistically significant effect on the incidence of postoperative complications in patients with acute appendicitis and cholecystitis (p = 0.561 and 0.547, respectively). A linear regression model showed a higher complication rate in patients with kidney disease (p = 0.014) and neoplasms (p = 0.013); the type of antibiotic therapy did not have a significant effect on the outcome (p = 0.765). There was no statistically significant difference in the post-treatment levels of creatinine in patients treated with aminoglycosides (gentamicin 3 mg/kg once daily) and in those who received other antibiotics (p = 0.75).

Aminoglycoside antibiotics target ribosomes and are effective against a wide range of bacteria. Here, we demonstrated that knockout strains related to energy metabolism in Escherichia coli showed increased tolerance to aminoglycosides during the mid-exponential growth phase. Contrary to expectations, these mutations did not reduce the proton motive force or aminoglycoside uptake, as there were no significant changes in metabolic indicators or intracellular gentamicin levels between wild-type and mutant strains. Our comprehensive proteomics analysis unveiled a noteworthy upregulation of proteins linked to the tricarboxylic acid (TCA) cycle in the mutant strains during the mid-exponential growth phase, suggesting that these strains compensate for the perturbation in their energy metabolism by increasing TCA cycle activity to maintain their membrane potential and ATP levels. Furthermore, our pathway enrichment analysis shed light on local network clusters displaying downregulation across all mutant strains, which were associated with both large and small ribosomal binding proteins, ribosome biogenesis, translation factor activity, and the biosynthesis of ribonucleoside monophosphates. These findings offer a plausible explanation for the observed tolerance of aminoglycosides in the mutant strains. Altogether, this research provides valuable insights into the mechanisms of aminoglycoside tolerance, paving the way for novel strategies to combat such cells.
Bacteria that are resistant to antibiotic drugs pose a significant challenge to human health around the globe. They have acquired genetic mutations that allow them to survive and grow in the presence of one or more antibiotics, making it harder for clinicians to eliminate such bacteria from human patients with life-threatening infections. Some bacteria may be able to temporarily develop tolerance to an antibiotic by altering how they grow and behave, without acquiring any new genetic mutations. Such drug-tolerant bacteria are more likely to survive long enough to gain mutations that may promote drug resistance. Recent studies suggest that genes involved in processes collectively known as energy metabolism, which convert food sources into the chemical energy cells need to survive and grow, may play a role in both tolerance and resistance. For example, Escherichia coli bacteria develop mutations in energy metabolism genes when exposed to members of a family of antibiotics known as the aminoglycosides. However, it remains unclear what exact role energy metabolism plays in antibiotic tolerance. To address this question, Shiraliyev and Orman studied how a range of E. coli strains with different genetic mutations affecting energy metabolism could survive in the presence of aminoglycosides. The experiments found that most of the mutant strains had a higher tolerance to the drugs than normal E. coli. Unexpectedly, this increased tolerance did not appear to be due to the drugs entering the mutant bacterium cells less than they enter normal cells (a common strategy of drug resistance and tolerance). Further experiments using a technique, known as proteomics, revealed that many genes involved in energy metabolism were upregulated in the mutant bacteria, suggesting these cells were compensating for the genetic abnormalities they have. Furthermore, the mutant bacteria had lower levels of the molecules the antibiotics target than normal bacteria. The findings of Shiraliyev and Orman offer critical insights into how bacteria become tolerant of aminoglycoside antibiotics. In the future, this may guide the development of new strategies to combat bacterial diseases.

BACKGROUND: Aminoglycosides have been a cornerstone of the treatment of nosocomial infections caused by Pseudomonas aeruginosa for over 80 years. However, escalating emergence of resistance poses a significant challenge. Therefore, this study aimed to investigate the prevailing patterns of aminoglycoside resistance among clinical isolates of P. aeruginosa in Iran; as well as the underlying resistance mechanisms observed in patients referred to Ardabil hospitals.
METHODS: A total of 200 isolates from five hospitals were evaluated. The resistance profiles of P. aeruginosa isolates to tobramycin, amikacin, and netilmicin were determined using the disk diffusion method. The capacity of aminoglycoside-resistant isolates to form biofilms was assessed through a phenotypic assay, and the results were confirmed using the gene amplification technique. The presence of genes associated with aminoglycoside resistance was detected using polymerase chain reaction (PCR). Quantitative reverse transcription PCR (qRT-PCR) was performed to measure the expression levels of genes encoding the MexXY-OprM efflux pump and PhoPQ two-component system (TCS).
RESULTS: The prevalence of aminoglycoside-resistant P. aeruginosa isolates was 48%, with 94.7% demonstrating multidrug resistance (MDR). All aminoglycoside-resistant P. aeruginosa strains exhibited biofilm-forming capabilities and harbored all the genes associated with biofilm production. Among the nine genes encoding 16S rRNA methylase and aminoglycoside-modifying enzymes, three genes were detected in these isolates: aac(6\')-Ib (85.4%), ant(2\'\')-Ia (18.7%), and aph(3\')-VI (3.1%). Additionally, all aminoglycoside-resistant P. aeruginosa isolates carried mexY and phoP genes, although the expression levels of mexY and phoP were 75% and 87.5%, respectively.
CONCLUSIONS: Given the considerably high prevalence of aminoglycoside-resistant P. aeruginosa strains, urgent measures are warranted to transition towards the use of novel aminoglycosides and to uphold vigilant surveillance of resistance patterns.

BACKGROUND: Ototoxicity is a major side effect of many broadly used aminoglycoside antibiotics (AGs) and no FDA-approved otoprotective drug is available currently. The zebrafish has recently become a valuable model to investigate AG-induced hair cell toxicity and an expanding list of otoprotective compounds that block the uptake of AGs have been identified from zebrafish-based screening; however, it remains to be established whether inhibiting intracellular cell death pathway(s) constitutes an effective strategy to protect against AG-induced ototoxicity.
RESULTS: We used the zebrafish model as well as in vitro cell-based assays to investigate AG-induced cell death and found that ferroptosis is the dominant type of cell death induced by neomycin. Neomycin stimulates lipid reactive oxygen species (ROS) accumulation through mitochondrial pathway and blocking mitochondrial ferroptosis pathway effectively protects neomycin-induced cell death. We screened an alkaloid natural compound library and identified seven small compounds that protect neomycin-induced ototoxicity by targeting ferroptosis pathway: six of them are radical-trapping agents (RTAs) while the other one (ellipticine) regulates intracellular iron homeostasis, which is essential for the generation of lipid ROS to stimulate ferroptosis.
CONCLUSIONS: Our study demonstrates that blocking intracellular ferroptosis pathway is an alternative strategy to ameliorate neomycin-induced ototoxicity and provides multiple hit compounds for further otoprotective drug development.

BACKGROUND: Pharmacokinetics of amikacin administered IV to neonatal foals are described, but little data are available regarding the plasma concentrations contributed by concurrent intra-articular (IA) administration.
OBJECTIVE: Compare the pharmacokinetics of amikacin when the total dose is administered IV compared to being divided between IV and IA routes of administration in neonatal foals and predict the plasma concentrations from various combined IV and IA dosing regimens.
METHODS: Eight healthy neonatal foals.
METHODS: Foals received 3 amikacin treatment protocols: (1) IV-only (25 mg/kg q24h IV), (2) concurrent IV and IA (16.7 mg/kg q24h IV and 8.3 mg/kg q24h into 1 tarsocrural joint), and (3) IA-only (8.3 mg/kg q24h into 1 tarsocrural joint). Protocols were administered for 3 days beginning at 7, 14, and 21 days of age. Plasma concentrations ≥53 μg/mL at 30 minutes were considered therapeutic for isolates with intermediate susceptibility.
RESULTS: Foal age was a significant variable. The IV-only protocol met or exceeded the 30-minute plasma concentrations considered therapeutic (mean μg/mL [95% confidence interval, CI]) in 7- to 9-day-old (54.0 [52.2-56.9]), 14- to 16-day-old (58.1 [55.2-61.0]), and 21- to 23-day-old (66.6 [63.7-69.6]) foals. Concurrent IV and IA protocol did not reach the 30-minute concentration considered therapeutic in 7- to 9-day-old foals (46.5 [43.6-49.4]) but did in 14- to 16-day-old (62.9 [60.0-65.8]) and 21-to 23-day-old (62.6 [59.7-65.6]) foals.
CONCLUSIONS: Concurrent IV and IA administration of amikacin produces 30-minute plasma concentrations considered therapeutic in foals 14 to 23 days old, but concentrations observed in younger foals might be below those considered therapeutic for isolates with intermediate susceptibility to amikacin.

Aminoglycosides are commonly used antibiotics for treatment of gram-negative bacterial infections, however, they might act on inner ear, leading to hair-cell death and hearing loss. Currently, there is no targeted therapy for aminoglycoside ototoxicity, since the underlying mechanisms of aminoglycoside-induced hearing impairments are not fully defined. This study aimed to investigate whether the calcium channel blocker verapamil and changes in intracellular & extracellular calcium could ameliorate aminoglycoside-induced ototoxicity in zebrafish. The present findings showed that a significant decreased number of neuromasts in the lateral lines of zebrafish larvae at 5 days\' post fertilization after neomycin (20 μM) and gentamicin (20 mg/mL) exposure, which was prevented by verapamil. Moreover, verapamil (10-100 μM) attenuated aminoglycoside-induced toxic response in different external calcium concentrations (33-3300 μM). The increasing extracellular calcium reduced hair cell loss from aminoglycoside exposure, while lower calcium facilitated hair cell death. In contrast, calcium channel activator Bay K8644 (20 μM) enhanced aminoglycoside-induced ototoxicity and reversed the protective action of higher external calcium on hair cell loss. However, neomycin-elicited hair cell death was not altered by caffeine, ryanodine receptor (RyR) agonist, and RyR antagonists, including thapsigargin, ryanodine, and ruthenium red. The uptake of neomycin into hair cells was attenuated by verapamil and under high external calcium concentration. Consistently, the production of reactive oxygen species (ROS) in neuromasts exposed to neomycin was also reduced by verapamil and high external calcium. Significantly, zebrafish larvae when exposed to neomycin exhibited decreased swimming distances in reaction to droplet stimulus when compared to the control group. Verapamil and elevated external calcium effectively protected the impaired swimming ability of zebrafish larvae induced by neomycin. These data imply that prevention of hair cell damage correlated with swimming behavior against aminoglycoside ototoxicity by verapamil and higher external calcium might be associated with inhibition of excessive ROS production and aminoglycoside uptake through cation channels. These findings indicate that calcium channel blocker and higher external calcium could be applied to protect aminoglycoside-induced listening impairments.

Rett syndrome (RTT) is a neurodevelopmental disorder resulting from genetic mutations in the methyl CpG binding protein 2 (MeCP2) gene. Specifically, around 35% of RTT patients harbor premature termination codons (PTCs) within the MeCP2 gene due to nonsense mutations. A promising therapeutic avenue for these individuals involves the use of aminoglycosides, which stimulate translational readthrough (TR) by causing stop codons to be interpreted as sense codons. However, the effectiveness of this treatment depends on several factors, including the type of stop codon and the surrounding nucleotides, collectively referred to as the stop codon context (SCC). Here, we develop a high-content reporter system to precisely measure TR efficiency at different SCCs, assess the recovery of the full-length MeCP2 protein, and evaluate its subcellular localization. We have conducted a comprehensive investigation into the intricate relationship between SCC characteristics and TR induction, examining a total of 14 pathogenic MeCP2 nonsense mutations with the aim to advance the prospects of personalized therapy for individuals with RTT. Our results demonstrate that TR induction can successfully restore full-length MeCP2 protein, albeit to varying degrees, contingent upon the SCC and the specific position of the PTC within the MeCP2 mRNA. TR induction can lead to the re-establishment of nuclear localization of MeCP2, indicating the potential restoration of protein functionality. In summary, our findings underscore the significance of SCC-specific approaches in the development of tailored therapies for RTT. By unraveling the relationship between SCC and TR therapy, we pave the way for personalized, individualized treatment strategies that hold promise for improving the lives of individuals affected by this debilitating neurodevelopmental disorder. KEY MESSAGES: The efficiency of readthrough induction at MeCP2 premature termination codons strongly depends on the stop codon context. The position of the premature termination codon on the transcript influences the readthrough inducibility. A new high-content dual reporter assay facilitates the measurement and prediction of readthrough efficiency of specific nucleotide stop contexts. Readthrough induction results in the recovery of full-length MeCP2 and its re-localization to the nucleus. MeCP2 requires only one of its annotated nuclear localization signals.

Staphylococcus haemolyticus 010503B is a multidrug-resistant bacterium isolated from an outpatient clinic in a hospital waiting area in Thailand. Here we present the draft genome sequence of S. haemolyticus 010503B. The paired-end reads were generated on the Illumina NextSeq 550 sequencer using genomic DNA from the pure culture of S. haemolyticus 010503B. The draft genome consisted of 114 contigs with a total size of 2,457,654 base pairs, an N50 of 57,312 base pairs and a GC content of 32.60%. The dDDH between 010503B and Staphylococcus haemolyticus SM 131T was 91.9%, identifying the strain as Staphylococcus haemolyticus. The data presented holds promise for bacterial classification, comparative genomics, analysing antimicrobial resistance comprehensively, and assessing bacterial virulence factors of S. haemolyticus. The draft genome sequence data has been deposited at NCBI under Bioproject accession number PRJNA550309.

UNASSIGNED: Pulmonary infections by gram-negative organisms are important in cystic fibrosis (CF). Aminoglycosides (AG) are often part of the treatment regimen. However, they are a well-known cause of ototoxicity. Even minimal hearing impairment in children could have a future impact on functional well-being.We aimed to investigate the progression of sensorineural hearing loss (SNHL) over several years in pediatric CF patients, and to identify risk factors, such as the use of AG, including both intravenous (IV) and inhaled AG.
UNASSIGNED: Retrospective analyses of patient records from children and adolescents followed up at the CF clinic of the Antwerp University Hospital, Belgium, were performed. We collected data on age, sex, pure-tone audiometry, and the use of AG. Descriptive and binary logistic regression analyses, and if indicated generalized estimating equations (GEE) analyses were performed.
UNASSIGNED: Forty pediatric patients were enrolled in the study taking part from 2013 to 2020. Pure-tone audiometry revealed an important rate of SNHL over several years, with a prevalence of 29 % for high-frequency SNHL (i.e. 8 kHz). Increasing age was identified as a significant risk factor for the development of SNHL at 8 kHz if 5 or more IV AG courses (p = 0.01) were reported or when IV AG were combined with inhaled AG (p = 0.002).
UNASSIGNED: Age combined with the use of IV AG (≥5 courses or in combination with inhaled AG) are predictive for developing high-frequency SNHL (i.e. 8 kHz). We suggest routine annual hearing screening (incl. high-frequency thresholds) in CF patients, starting from childhood.

Amikacin is an FDA-approved aminoglycoside antibiotic that is commonly used. However, validated dosage regimens that achieve clinically relevant exposure profiles in mice are lacking. We aimed to design and validate humanized dosage regimens for amikacin in immune-competent murine bloodstream and lung infection models of Acinetobacter baumannii. Plasma and lung epithelial lining fluid (ELF) concentrations after single subcutaneous doses of 1.37, 13.7, and 137 mg/kg of body weight were simultaneously modeled via population pharmacokinetics. Then, humanized amikacin dosage regimens in mice were designed and prospectively validated to match the peak, area, trough, and range of plasma concentration profiles in critically ill patients (clinical dose: 25-30 mg/kg of body weight). The pharmacokinetics of amikacin were linear, with a clearance of 9.93 mL/h in both infection models after a single dose. However, the volume of distribution differed between models, resulting in an elimination half-life of 48 min for the bloodstream and 36 min for the lung model. The drug exposure in ELF was 72.7% compared to that in plasma. After multiple q6h dosing, clearance decreased by ~80% from the first (7.35 mL/h) to the last two dosing intervals (~1.50 mL/h) in the bloodstream model. Likewise, clearance decreased by 41% from 7.44 to 4.39 mL/h in the lung model. The humanized dosage regimens were 117 mg/kg of body weight/day in mice [administered in four fractions 6 h apart (q6h): 61.9%, 18.6%, 11.3%, and 8.21% of total dose] for the bloodstream and 96.7 mg/kg of body weight/day (given q6h as 65.1%, 16.9%, 10.5%, and 7.41%) for the lung model. These validated humanized dosage regimens and population pharmacokinetic models support translational studies with clinically relevant amikacin exposure profiles.