Nocardia keratitis after small incision lenticule extraction (SMILE).

We report the case of a female patient in her late 20s who visited the clinic with concerns about poor vision, redness, watering and a burning sensation in her left eye 2 weeks after undergoing a small incision lenticule extraction. She had no history of systemic illness or immunosuppressed status. On slit lamp examination, she was found to have corneal stromal infiltrates in the interface at multiple locations. Given the clinical diagnosis of microbial keratitis, corneal scraping of the interface infiltrate was performed and sent for microbiological examination revealing gram-positive, thin, beaded filaments that were acid-fast positive and later identified by growth in culture media as Nocardia species. This case was managed successfully with the use of topical amikacin and systemic trimethoprim-sulfamethoxazole with complete resolution of infection.

Assessment of three antibiotic combination regimens against Gram-negative bacteria causing neonatal sepsis in low- and middle-income countries.

Gram-negative bacteria (GNB) are a major cause of neonatal sepsis in low- and middle-income countries (LMICs). Although the World Health Organization (WHO) reports that over 80% of these sepsis deaths could be prevented through improved treatment, the efficacy of the currently recommended first- and second-line treatment regimens for this condition is increasingly affected by high rates of drug resistance. Here we assess three well known antibiotics, fosfomycin, flomoxef and amikacin, in combination as potential antibiotic treatment regimens by investigating the drug resistance and genetic profiles of commonly isolated GNB causing neonatal sepsis in LMICs. The five most prevalent bacterial isolates in the NeoOBS study (NCT03721302) are Klebsiella pneumoniae, Acinetobacter baumannii, E. coli, Serratia marcescens and Enterobacter cloacae complex. Among these isolates, high levels of ESBL and carbapenemase encoding genes are detected along with resistance to ampicillin, gentamicin and cefotaxime, the current WHO recommended empiric regimens. The three new combinations show excellent in vitro activity against ESBL-producing K. pneumoniae and E. coli isolates. Our data should further inform and support the clinical evaluation of these three antibiotic combinations for the treatment of neonatal sepsis in areas with high rates of multidrug-resistant Gram-negative bacteria.

Proficiency of phenotypic drug susceptibility testing for Mycobacterium tuberculosis in China, 2008-2021.

To analyze the results of proficiency testing for anti-tuberculosis drug susceptibility testing (DST) in China. Number of laboratory participating the proficiency testing performed DST, and the sensitivity, specificity, reproducibility, and accordance rate were calculated from data of 13 rounds proficiency testing results for DST from 2008 to 2021. A total of 30 and 20 strains of Mycobacterium tuberculosis with known susceptibility results were sent to each laboratory in 2008 to 2019, 2020 and 2021, respectively. The number of participating laboratories ranged from 30 in 2009 to 546 in 2021. L-J DST was the predominant method. The specificity presented relatively higher than sensitivity. Improvement of specificity were observed for all drugs through the years, while sensitivity did not show improvement for amikacin and capreomycin. Accordance rate of pyrazinamide and kanamycin and reproducibility of capreomycin and pyrazinamide were not significantly improved through the years. Most of the participating laboratories significantly improved the quality of their DST through the consecutive rounds of proficiency testing except for second-line injectable drugs and pyrazinamide. The results highlight the importance of developing novel and/or improving existing methods for phenotypic DST for certain drugs.

P-gp inhibition and enhanced oral bioavailability of amikacin Sulfate: A novel approach using Thiolated Chito-PEGylated Lipidic Hybrids.

This study aimed to develop oral lipidic hybrids of amikacin sulfate (AMK), incorporating thiolated chitosan as a P-glycoprotein (P-gp) inhibitor to enhance intestinal absorptivity and bioavailability. Three formulations were designed: PEGylated Liposomes, Chitosan-functionalized PEGylated (Chito-PEGylated) Lipidic Hybrids, and Thiolated Chito-PEGylated Lipidic Hybrids. The physical characteristics of nanovesicles were assessed. Ex-vivo permeation and confocal laser scanning microscopy (CLSM) studies were conducted to evaluate the formulations' potential to enhance AMK intestinal permeability. In-vivo pharmacokinetic studies in rats and histological/biochemical investigations assessed the safety profile and oral bioavailability. The AMK-loaded Thiolated Chito-PEGylated Lipidic Hybrids exhibited favorable physical characteristics, higher ex-vivo permeation parameters, and verified P-gp inhibition via CLSM. They demonstrated heightened oral bioavailability (68.62% absolute bioavailability) and a sufficient safety profile. Relative bioavailability was significantly higher (1556.3% and 448.79%) compared to PEGylated Liposomes and Chito-PEGylated Lipidic Hybrids, respectively, indicating remarkable oral AMK delivery with fewer doses, reduced side effects, and enhanced patient compliance.

Clinical characteristics and antibiotic treatment of peritoneal dialysis-associated peritonitis caused by Pseudomonas species: a review of 15 years' experience from southern China.

Pseudomonas can lead to peritoneal dialysis-associated peritonitis, which is characterized by a poor prognosis, such as a substantial failure rate and a high death rate. This study aimed to provide an overview of Pseudomonas peritonitis's clinical features, the regimens of antibiotic, antibiotic resistance, and outcomes in peritoneal dialysis (PD) patients. This study observed patients with Pseudomonas peritonitis in two large PD centers in South China from January 2008 to December 2022. The demographics, symptomatology, antibiotics regimens, resistance to common antibiotics, and clinical outcomes of all included patients were reviewed. A total of 3,459 PD patients were included, among them 57 cases of peritonitis caused by Pseudomonas, including 48 cases (84.2%) of Pseudomonas aeruginosa. The incidence rate of Pseudomonas peritonitis was 0.0041 episode per patient-year. Of them, 28.1% (16 cases) of the patients were accompanied by exit site infection (ESI), and all had abdominal pain and turbid ascites at the time of onset. The most commonly used antibiotic combination was ceftazidime combined with amikacin. Approximately 89% of Pseudomonas species were sensitive to ceftazidime, and 88% were sensitive to amikacin. The overall primary response rate was 28.1% (16 patients), and the complete cure rate was 40.4% (23 patients). There was no significant difference in the complete cure rate of peritonitis using three and other antibiotic treatment regimens (44.8% vs 46.4%; P = 0.9). The successful treatment group had higher baseline albumin level (35.9 ± 6.2; P = 0.008) and residual urine volume (650.7 ± 375.5; P = 0.04). Although the incidence of peritonitis caused by Pseudomonas was low, the symptoms were serious, and prognosis was very poor. Pseudomonas was still highly susceptible to first-line antibiotics currently in use against Gram-negative bacteria. Patients with successful treatment had higher albumin levels and higher urine output. IMPORTANCE: Although the incidence of peritoneal dialysis-associated peritonitis caused by Pseudomonas is very low, it seriously affects the technique survival of peritoneal dialysis patients. However, there are few studies and reports on Pseudomonas peritonitis in the Chinese mainland area. Therefore, the purpose of this study is to describe the clinical characteristics, the regimens of antibiotic, drug resistance, and outcome of peritoneal dialysis patients in southern China in the past 15 years and summarize the clinical experience in the treatment of Pseudomonas peritonitis.

Mycobacterium senegalense catheter-related bloodstream infection.

Catheter-related bloodstream infection (CRBSI) is one of the common healthcare-acquired infections imposing a high burden of morbidity and mortality on the patients. Non-tuberculous mycobacterium is a rare aetiology for CRBSI and poses challenges in laboratory diagnosis and clinical management. This is a case of a woman in her early 60s with underlying end-stage renal failure, diabetes mellitus and hypertension presented with a 2-week history of high-grade fever postregular haemodialysis, vomiting, lethargy and altered mental status.Blood cultures from a permanent catheter and peripheral taken concurrently yielded Mycobacterium senegalense, identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, which established the diagnosis of CRBSI atypically presented with concurrent acute intracranial bleeding and cerebrovascular infarction at initial presentation. She was started on a combination of oral azithromycin, oral amikacin and intravenous imipenem, and the permanent catheter was removed. Despite the treatments instituted, she developed septicaemia, acute myocardial infarction and macrophage activation-like syndrome, causing the patient's death.

Successful management of Mycobacterium abscessus pneumonia in a 53-day-old immunocompetent infant.

Pulmonary infection due to Mycobacterium abscessus complex (MABC) usually occurs in children with underlying risk factors including cystic fibrosis (CF), chronic lung disease, and immunocompromised status, but rarely in immunocompetent children without underlying lung disease, especially in infants. We present a case of MABC pulmonary disease (MABC-PD) in an otherwise healthy 53-day-old male infant with one week of cough and respiratory distress. Computed tomography showed multiple masses across both lungs. Isolated mycobacteria from his bronchoalveolar lavage fluid were identified as MABC. We describe our complete evaluation, including immunodeficiency evaluation incorporating whole exome sequencing and our therapeutic process given complicated susceptibility pattern of the M. abscessus isolate, and review literature for MABC-PD in immunocompetent children. The infant was successfully treated through prolonged treatment with parenteral Amikacin, Cefoxitin, Linezolid, and Clarithromycin, combined with inhaled Amikacin.

Pharmacometric in silico studies used to facilitate a national dose standardisation process in neonatology - application to amikacin.

BACKGROUND AND AIMS: Pharmacometric in silico approaches are frequently applied to guide decisions concerning dosage regimes during the development of new medicines. We aimed to demonstrate how such pharmacometric modelling and simulation can provide a scientific rationale for optimising drug doses in the context of the Swiss national dose standardisation project in paediatrics using amikacin as a case study. METHODS: Amikacin neonatal dosage is stratified by post-menstrual age (PMA) and post-natal age (PNA) in Switzerland and many other countries. Clinical concerns have been raised for the subpopulation of neonates with a post-menstrual age of 30-35 weeks and a post-natal age of 0-14 days ("subpopulation of clinical concern"), as potentially oto-/nephrotoxic trough concentrations (Ctrough >5 mg/l) were observed with a once-daily dose of 15 mg/kg. We applied a two-compartmental population pharmacokinetic model (amikacin clearance depending on birth weight and post-natal age) to real-world demographic data from 1563 neonates receiving anti-infectives (median birth weight 2.3 kg, median post-natal age six days) and performed pharmacometric dose-exposure simulations to identify extended dosing intervals that would ensure non-toxic Ctrough (Ctrough <5 mg/l) dosages in most neonates. RESULTS: In the subpopulation of clinical concern, Ctrough <5 mg/l was predicted in 59% versus 79-99% of cases in all other subpopulations following the current recommendations. Elevated Ctrough values were associated with a post-natal age of less than seven days. Simulations showed that extending the dosing interval to ≥36 h in the subpopulation of clinical concern increased the frequency of a desirable Ctrough below 5 mg/l to >80%. CONCLUSION: Pharmacometric in silico studies using high-quality real-world demographic data can provide a scientific rationale for national paediatric dose optimisation. This may increase clinical acceptance of fine-tuned standardised dosing recommendations and support their implementation, including in vulnerable subpopulations.

Nationwide genome surveillance of carbapenem-resistant Pseudomonas aeruginosa in Japan.

Japan is a country with an approximate 10% prevalence rate of carbapenem-resistant Pseudomonas aeruginosa (CRPA). Currently, a comprehensive overview of the genotype and phenotype patterns of CRPA in Japan is lacking. Herein, we conducted genome sequencing and quantitative antimicrobial susceptibility testing for 382 meropenem-resistant CRPA isolates that were collected from 78 hospitals across Japan from 2019 to 2020. CRPA exhibited susceptibility rates of 52.9%, 26.4%, and 88.0% against piperacillin-tazobactam, ciprofloxacin, and amikacin, respectively, whereas 27.7% of CRPA isolates was classified as difficult-to-treat resistance P. aeruginosa. Of the 148 sequence types detected, ST274 (9.7%) was predominant, followed by ST235 (7.6%). The proportion of urine isolates in ST235 was higher than that in other STs (P = 0.0056, χ2 test). Only 4.1% of CRPA isolates carried the carbapenemase genes: blaGES (2) and blaIMP (13). One ST235 isolate carried the novel blaIMP variant blaIMP-98 in the chromosome. Regarding chromosomal mutations, 87.1% of CRPA isolates possessed inactivating or other resistance mutations in oprD, and 28.8% showed mutations in the regulatory genes (mexR, nalC, and nalD) for the MexAB-OprM efflux pump. Additionally, 4.7% of CRPA isolates carried a resistance mutation in the PBP3-encoding gene ftsI. The findings from this study and other surveillance studies collectively demonstrate that CRPA exhibits marked genetic diversity and that its multidrug resistance in Japan is less prevailed than in other regions. This study contributes a valuable data set that addresses a gap in genotype/phenotype information regarding CRPA in the Asia-Pacific region, where the epidemiological background markedly differs between regions.

Pharmacokinetics of amikacin after intravenous, intra-articular, and combined intravenous and intra-articular administration in healthy neonatal foals.

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. HYPOTHESIS/OBJECTIVES: 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. ANIMALS: 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 AND CLINICAL IMPORTANCE: 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.

A pH/ROS-responsive antioxidative and antimicrobial GelMA hydrogel for on-demand drug delivery and enhanced osteogenic differentiation in vitro.

Long-term inflammation, including those induced by bacterial infections, contributes to the superfluous accumulation of reactive oxygen species (ROS), further aggravating this condition, decreasing the local pH, and adversely affecting bone defect healing. Conventional drug delivery scaffold materials struggle to meet the demands of this complex and dynamic microenvironment. In this work, a smart gelatin methacryloyl (GelMA) hydrogel was synthesized for the dual delivery of proanthocyanidin and amikacin based on the unique pH and ROS responsiveness of boronate complexes. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrated the co-crosslinking of two boronate complexes with GelMA. The addition of the boronate complexes improved the mechanical properties, swelling ratio, degradation kinetics and antioxidative properties of the hydrogel. The hydrogel exhibited pH and ROS responses and a synergistic control over the drug release. Proanthocyanidin was responsively released to protect mouse osteoblast precursor cells from oxidative stress and promote their osteogenic differentiation. The hydrogel responded to pH changes and released sufficient amikacin in a timely manner, thereby exerting an efficient antimicrobial effect. Overall, the hydrogel delivery system exhibited a promising strategy for solving infectious and inflammatory problems in bone defects and promoting early-stage bone healing.

Occurrence and characterization of rmtB-harbouring Salmonella and Escherichia coli isolates from a pig farm in the UK.

OBJECTIVES: To characterize and elucidate the spread of amikacin-resistant Enterobacteriaceae isolates from environmental samples on a pig farm in the UK, following the previous identification of index Salmonella isolates harbouring the rmtB gene, a 16S rRNA methylase. METHODS: Environmental samples were collected during two visits to a pig farm in the UK. Isolates were recovered using selective media (amikacin 128 mg/L) followed by real-time PCR and WGS to analyse rmtB-carrying Salmonella and Escherichia coli isolates. RESULTS: Salmonella and E. coli isolates harbouring the rmtB gene were detected at both farm visits. All Salmonella isolates were found to be monophasic S. enterica serovar Typhimurium variant Copenhagen of ST34. rmtB-harbouring E. coli isolates were found to be one of three STs: ST4089, ST1684 and ST34. Long-read sequencing identified the rmtB gene to be chromosomally located in Salmonella isolates and on IncFII-type plasmids in E. coli isolates. The results showed the rmtB gene to be flanked by IS26 elements and several resistance genes. CONCLUSIONS: We report on the occurrence of rmtB-harbouring Enterobacteriaceae on a pig farm in the UK. rmtB confers resistance to multiple aminoglycosides and this work highlights the need for surveillance to assess dissemination and risk.

Faster perfusate instillation time results in more systemic leakage of amikacin sulfate when performing intravenous regional limb perfusion in horses.

OBJECTIVE: To evaluate if a difference in synovial amikacin concentrations exists in the radiocarpal joint (RCJ) following different durations of instillation of an IV regional limb perfusion (IVRLP) perfusate. ANIMALS: 7 healthy horses. METHODS: Horses received 2 IVRLPs with 2 g amikacin diluted to 60 mL with 0.9% NaCl via the cephalic vein in a crossover study design with a wash-out period between procedures. Instillation of the perfusate was administered over a 1-minute (technique 1) and 5-minute (technique 5) period. Concentrations of amikacin within the RCJ were measured at time (T) 5, 10, 15, 20, 25, and 30 minutes after instillation of the perfusate. Systemic concentrations of amikacin were measured at T0, 5, 10, 15, 20, 25, 29 minutes, and 1 minute after tourniquet removal (T31). Amikacin concentrations were determined by fluorescence polarization immunoassay. RESULTS: The median maximum concentration (CMAX) of amikacin within the RCJ for technique 1 was 338.4 µg/mL (range, 60 to 4,925 µg/mL), while the median CMAX for technique 5 was higher at 694.8 µg/mL (range, 169.2 to 3,410 µg/mL; P = .398). There was a higher amikacin blood concentration over time for technique 1 compared to technique 5 (P = .004). CLINICAL RELEVANCE: Administration of perfusate at different rates did not significantly affect synovial concentration of amikacin within the RCJ when performing IVRLP. However, increased systemic leakage was noted when the perfusate was administered over 1 minute, which might affect synovial concentrations in a larger group of horses.

D-histidine combated biofilm formation and enhanced the effect of amikacin against Pseudomonas aeruginosa in vitro.

Pseudomonas aeruginosa is an opportunistic gram-negative pathogenic microorganism that poses a significant challenge in clinical treatment. Antibiotics exhibit limited efficacy against mature biofilm, culminating in an increase in the number of antibiotic-resistant strains. Therefore, novel strategies are essential to enhance the effectiveness of antibiotics against Pseudomonas aeruginosa biofilms. D-histidine has been previously identified as a prospective anti-biofilm agent. However, limited attention has been directed towards its impact on Pseudomonas aeruginosa. Therefore, this study was undertaken to explore the effect of D-histidine on Pseudomonas aeruginosa in vitro. Our results demonstrated that D-histidine downregulated the mRNA expression of virulence and quorum sensing (QS)-associated genes in Pseudomonas aeruginosa PAO1 without affecting bacterial growth. Swarming and swimming motility tests revealed that D-histidine significantly reduced the motility and pathogenicity of PAO1. Moreover, crystal violet staining and confocal laser scanning microscopy demonstrated that D-histidine inhibited biofilm formation and triggered the disassembly of mature biofilms. Notably, D-histidine increased the susceptibility of PAO1 to amikacin compared to that in the amikacin-alone group. These findings underscore the efficacy of D-histidine in combating Pseudomonas aeruginosa by reducing biofilm formation and increasing biofilm disassembly. Moreover, the combination of amikacin and D-histidine induced a synergistic effect against Pseudomonas aeruginosa biofilms, suggesting the potential utility of D-histidine as a preventive strategy against biofilm-associated infections caused by Pseudomonas aeruginosa.

Design and development of dual drug-loaded nanofibrous inserts for ophthalmic sustained delivery of AMK and VAN: Pharmacokinetic study in rabbit's eye.

Bacterial corneal keratitis is a damage to the corneal tissue that if not treated, can cause various complications like severe vision loss or even blindness. Combination therapy with two antibiotics which are effective against Gram-positive and Gram-negative bacteria offers sufficient broad-spectrum antibiotic coverage for the treatment of keratitis. Nanofibers can be a potential carrier in dual drug delivery due to their structural characteristics, specific surface area and high porosity. In order to achieve a sustained delivery of amikacin (AMK) and vancomycin (VAN), the current study designed, assessed, and compared nanofibrous inserts utilizing polyvinyl alcohol (PVA) and polycaprolactone (PCL) as biocompatible polymers. Electrospinning method was utilized to prepare two different formulations, PVA-VAN/AMK and PCL/PVA-VAN/AMK, with 351.8 ± 53.59 nm and 383.85 ± 49 nm diameters, respectively. The nanofibers were simply inserted in the cul-de-sac as a noninvasive approach for in vivo studies. The data obtained from the physicochemical and mechanical properties studies confirmed the suitability of the formulations. Antimicrobial investigations showed the antibacterial properties of synthesized nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa. Both in vitro and animal studies demonstrated sustained drug release of the prepared nanofibers for 120 h. Based on the in vivo findings, the prepared nanofibers' AUC0-120 was found to be 20 to 31 times greater than the VAN and AMK solutions. Considering the results, the nanofibrous inserts can be utilized as an effective and safe system in drug delivery.

In vitro activity of selected antimicrobials against methicillin-resistant Staphylococcus pseudintermedius of canine origin in Poland.

BACKGROUND: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an important veterinary pathogen. In general, only a few antimicrobials show in vitro activity against MRSP isolates. OBJECTIVES: The objective of this study was to determine the in vitro activity of selected antimicrobials, including last-choice drugs, against clinical MRSP isolates of canine origin. The activity of 10 selected agents was evaluated against 41 clinical MRSP isolates. METHODS: The disk diffusion method and minimal inhibitory concentration values were used for antimicrobial susceptibility testing (AST). The guidelines for staphylococci of canine or human origin were employed for the interpretation of the results. RESULTS: Among the examined MRSP isolates, resistance to enrofloxacin and clindamycin was the most prevalent (n = 40; 97.6%). Resistance to doxycycline and gentamicin was observed in 83.0% (n = 34) and 68.3% (n = 28) of the isolates, respectively. Single isolates were resistant to chloramphenicol (n = 5; 12.2%) and rifampicin (n = 3; 7.3%), whereas all showed susceptibility to amikacin, vancomycin, mupirocin and linezolid. Predominantly, the results of AST obtained by both methods were consistent. Some discrepancies were observed for gentamicin; however, clinical breakpoints for staphylococci of human origin were used. CONCLUSIONS: Amikacin and chloramphenicol constitute potential treatment options in infections caused by MRSP and may be included in extended susceptibility testing in our geographical region. The determination of clinical breakpoints for some antimicrobials not incorporated in the recommendations should be a high priority in the veterinary diagnostics.

Antibiotic Resistance, Biofilm Formation, and Persistent Phenotype of Klebsiella pneumoniae in a Vietnamese Tertiary Hospital: A Focus on Amikacin.

Klebsiella pneumoniae stands out as a major opportunistic pathogen responsible for both hospital- and community-acquired bacterial infections. This study comprehensively assesses the antibiotic resistance, amikacin persistent patterns, and biofilm-forming ability of 247 isolates of K. pneumoniae obtained from an intensive care unit of a tertiary hospital in Vietnam. Microdilution assays, conducted on a 96-well plate, determined the minimum inhibitory concentrations (MICs) of amikacin. Susceptibility data for other antibiotics were gathered from the antibiogram profile. Stationary-phase bacteria were exposed to 50 × MIC, and viable bacteria counts were measured to determine amikacin persistence. Biofilm forming capacity on 96-well polystyrene surfaces was assessed by biomass and viable bacteria. The prevalence of resistance was notably high across most antibiotics, with 64.8% classified as carbapenem-resistant K. pneumoniae and 81.4% as multidrug resistant. Amikacin, however, exhibited a relatively low rate of resistance. Of the isolates, 58.2% demonstrated a moderate to strong biofilm formation capacity, and these were found to be poorly responsive to amikacin. K. pneumoniae reveals a significant inclination for amikacin persistence, with ∼45% of isolates displaying an antibiotic antibiotic-survival ratio exceeding 10%. The study sheds light on challenges in treating of K. pneumoniae infection in Vietnam, encompassing a high prevalence of antibiotic resistance, a substantial ability to form biofilm, and a notable rate of antibiotic persistence.

Murepavadin promotes the killing efficacies of aminoglycoside antibiotics against Pseudomonas aeruginosa by enhancing membrane potential.

Murepavadin is a peptidomimetic that specifically targets the lipopolysaccharide transport protein LptD of Pseudomonas aeruginosa. Here, we found that murepavadin enhances the bactericidal efficacies of tobramycin and amikacin. We further demonstrated that murepavadin enhances bacterial respiration activity and subsequent membrane potential, which promotes intracellular uptake of aminoglycoside antibiotics. In addition, the murepavadin-amikacin combination displayed a synergistic bactericidal effect in a murine pneumonia model.

Fluorescent reporters give new insights into antibiotics-induced nonsense and frameshift mistranslation.

We developed a reporter system based on simultaneous expression of two fluorescent proteins: GFP as a reporter of the capacity of protein synthesis and mutated mScarlet-I as a reporter of translational errors. Because of the unique stop codons or frameshift mutations introduced into the mScarlet-I gene, red fluorescence was produced only after a mistranslation event. These reporters allowed us to estimate mistranslation at a single cell level using either flow cytometry or fluorescence microscopy. We found that laboratory strains of Escherichia coli are more prone to mistranslation compared to the clinical isolates. As relevant for uropathogenic E. coli, growth in human urine elevated translational frameshifting compared to standard laboratory media, whereas different standard media had a small effect on translational fidelity. Antibiotic-induced mistranslation was studied by using amikacin (aminoglycoside family) and azithromycin (macrolide family). Bactericidal amikacin induced preferably stop-codon readthrough at a moderate level. Bacteriostatic azithromycin on the other hand induced both frameshifting and stop-codon readthrough at much higher level. Single cell analysis revealed that fluorescent reporter-protein signal can be lost due to leakage from a fraction of bacteria in the presence of antibiotics, demonstrating the complexity of the antimicrobial activity.

Emergence and clonal expansion of Aeromonas hydrophila ST1172 that simultaneously produces MOX-13 and OXA-724.

BACKGROUND: Aeromonas hydrophila infections can cause gastrointestinal symptoms such as diarrhea; however, deep infections are rarely reported. Outbreaks of A. hydrophila are reported more frequently in fish, poultry, and snakes than in humans. This study aimed to track clonal relatedness of deep infections caused by A. hydrophila using whole genome sequencing (WGS). METHODS: We collected three isolates of A. hydrophila in July 19 to August 29, 2019, from patients that underwent spine surgery. Accurate species identification was performed using whole-genome average nucleotide identity (ANI). Antimicrobial susceptibility testing was performed using a VITEK 2 automated AST-N334 Gram-negative susceptibility card system. Antimicrobial resistance and virulence genes were identified using the Comprehensive Antibiotic Resistance Database and Virulence Factor Database VFanalyzer. RESULTS: All three isolates were identified as A. hydrophila based on ANI and multilocus sequence typing analysis revealed that A. hydrophila belonged to a novel sequence type (ST1172). All three isolates were susceptible to amikacin and levofloxacin; however, they were resistant to piperacillin/tazobactam, ceftriaxone, cefuroxime, cefoxitin, and imipenem. Isolate 19W05620 (patient 3) showed increased ceftazidime resistance (minimum inhibitory concentration ≥ 64 µg/mL). All three isolates possessed the same chromosomally encoded ß-lactamases, including blaOXA-724 (ß-lactamase), imiH (metallo-ß-lactamase), and blaMOX-13 (AmpC) in plasmids. CONCLUSIONS: Our study validated the transmission of a novel carbapenem-resistant A. hydrophila sequence type (ST1172) in patients that underwent spine surgery. Control measures should be developed to prevent dissemination of A. hydrophila in the hospital setting.