MSC-derived exosomes protect auditory hair cells from neomycin-induced damage via autophagy regulation

BACKGROUND: Sensorineural hearing loss (SNHL) poses a major threat to both physical and mental health; however, there is still a lack of effective drugs to treat the disease. Recently, novel biological therapies, such as mesenchymal stem cells (MSCs) and their products, namely, exosomes, are showing promising therapeutic potential due to their low immunogenicity, few ethical concerns, and easy accessibility. Nevertheless, the precise mechanisms underlying the therapeutic effects of MSC-derived exosomes remain unclear. RESULTS: Exosomes derived from MSCs reduced hearing and hair cell loss caused by neomycin-induced damage in models in vivo and in vitro. In addition, MSC-derived exosomes modulated autophagy in hair cells to exert a protective effect. Mechanistically, exogenously administered exosomes were internalized by hair cells and subsequently upregulated endocytic gene expression and endosome formation, ultimately leading to autophagy activation. This increased autophagic activity promoted cell survival, decreased the mitochondrial oxidative stress level and the apoptosis rate in hair cells, and ameliorated neomycin-induced ototoxicity. CONCLUSIONS: In summary, our findings reveal the otoprotective capacity of exogenous exosome-mediated autophagy activation in hair cells in an endocytosis-dependent manner, suggesting possibilities for deafness treatment.

Intratympanic Gentamicin Injection in Ménière’s Disease: Our Ten Years’ Experience and Outcomes

Objective: The aim of our study is to evaluate the effectiveness of intratympanic gentamicin injection (ITG) on vertigo control with reduced doses and its hearing effects. Materials and Method: The study was conducted at Otolaryngology Department of AORN “S.G. Moscati” between January 2005 and January 2015 on 72 patients with disabling unilateral Meniere’s disease. We use 0.2-0.3 mL of gentamicin sulfate at a concentration of 40mg/ml, injected into the affected ear through the posterior-inferior quadrant of the tympanic membrane. The procedure was carried out for three following days. Main outcome measures: vertigo control and hearing threshold changes after ITG treatment. Results: In 98.6% of the patients(n=71) the ITG produced the full remission of the vertiginous symptoms. In 91.6% of cases(n=66) a single treatment (three consequent injections) was sufficient to control vertigo, in 5.5% of cases(n=4) two treatments were necessary to control vertigo and in 1.3% of patients(n=1) three treatments were necessary to control vertigo. In no case we have had hearing loss after ITG procedure. The pre-treatment pure tone average was 48db. The post-treatment pure tone average was 49.2db. This difference was no statistical difference. Conclusion: In this study we reported high vertigo control, long follow-up and no case of significant hearing worsening. We consider the three injections in the following three days with low doses of gentamicin a safe and valid treatment for Meniere’s disease.

Eficacia de la terapia con aminoglicósidos en infectados por Klelsiella pneumoniae resis-tente a carbapenémicos / Efficacy of aminoglycoside therapy in patients infected with Carbapenem-Resistant Klel-siella pneumoniae

El tratamiento de infecciones por bacterias resistentes a determinados grupos farmacológicos resulta un tema de alto interés para la ciencia. Así, la investigación tuvo el propósito de sistema-tizar la información acerca de la eficacia de los aminoglicósidos en pacientes infectados por Klebsiella pneumoniae resiste a carbapenémicos; para lo que se hizo una revisión sistemática siguiendo el protocolo PRISMA. Las fuentes se ubicaron a partir de una pesquisa se hizo en las bases de datos: PubMed, MEDLINE y SCOPUS; quedando seleccionados 11 artículos que cumplieron con los requisitos establecidos. Se observó un predominio de los artículos provenientes de los Estados Unidos de América (4/11) y Brasil (3/11). La población global fue de 3778 pacientes entre las 11 investigaciones incluidas. El uso de aminoglicósidos resultó más eficaz que otros grupos farmacológicos en la mejoría en el estado clínico, reflejando menores valores de mortalidad en pacientes hospitalizados por la infección en cuestión.

The treatment of infections by bacteria resistant to certain pharmacological groups is a topic of great interest for science. Thus, the research had the purpose of systematizing the information about the efficacy of aminoglycosides in patients infected by Carbapenem-Resistant Klebsiella pneumoniae. This systematic review was carried out following the PRISMA protocol. The sour-ces were located from a search made in the databases: PubMed, MEDLINE, and SCOPUS; 11 articles were selected that met the established requirements. A predominance of articles from the United States of America (4/11) and Brazil (3/11) was observed. The overall population was 3,778 patients among the 11 studies included. The use of aminoglycosides was more effective than other pharmacological groups in improving clinical status, reflecting lower mortality values in patients hospitalized for the infection in question

Aminoglycoside resistance in domestic sewage and clinical Escherichia coli isolates

SUMMARY Introduction: Escherichia coli, a Gram-negative bacillus, is found in diverse environments and causes several human diseases, such as pneumonia and urinary tract infections. Aminoglycosides are antimicrobials that present high activity against Gram-negative species, including multidrug-resistant pathogens. However, the indiscriminate use of these compounds has selected resistant microorganisms, mainly due to the production of aminoglycoside-modifying enzymes (AME). Material and methods: The minimal inhibitory concentration of the aminoglycosides amikacin, gentamicin, and neomycin against clinical (CI, n = 52, only urinary) and domestic sewage (DS, n = 33) E. coli isolates was determined by the microdilution method, according to the European Committee on Antimicrobial Susceptibility Testing. The presence of AMEs among E. coli isolates was determined based on the susceptibility profile to amikacin, gentamicin, kanamycin, and tobramycin, according to Mancini et al. (2019). Results: Overall, 33.3% of the DS isolates and 100% of the CI isolates presented mechanisms of resistance to amikacin, gentamicin, or neomycin. The extended-spectrum beta-lactamase enzymes-producing isolates (23/27, 85%) showed mechanisms of resistance to gentamicin and/or neomycin and resistance to amikacin was simultaneously observed only in CI isolates. All DS isolates were considered wild-type-no AME, while APH (3') (14/52) and AAC (3') (10/52) enzymes were detected among CI isolates, one of which produces APH (3') and AAC (6')-I simultaneously. Conclusion: Resistance to aminoglycosides is present among E. coli isolates in Brazil, but to a lesser extent in environmental isolates. Besides, AMEs are frequent in CI isolates, and surveillance for antimicrobial resistance should be implemented to monitor aminoglycoside-resistant E. coli infections.

Introducción: Escherichia coli se encuentra en diversos ambientes y causa enfermedades humanas. Los aminoglucósidos son antimicrobianos que presentan actividad contra especies gramnegativas. Sin embargo, el uso indiscriminado de estos compuestos ha seleccionado microorganismos resistentes, principalmente debido a la producción de enzimas modificadoras de aminoglucósidos (AME). Material y métodos: La concentración mínima inhibitoria de aminoglucósidos frente a aislados de E.coli clínicos (CI, n = 52) y de aguas residuales sanitarias (DS, n = 33) se determinó mediante el método de microdilución, según la European Committee on Antimicrobial Susceptibility Testing. La presencia de AME se determinó con base en el perfil de susceptibilidad a amikacina, gentamicina, kanamicina y tobra-micina, según Mancini et al. (2019). Resultados: 33,3% de los aislados de DS y 100% de los CI presentaron resistencia a amikacina, gentamicina o neomicina. Los aislados productores de enzimas betalactamasas de espectro extendido (23/27, 85%) mostraron resistencia a gentamicina y/o neomicina y la resistencia a amikacina se observó simultáneamente solo en CI. Todos los aislados de DS se consideraron wild type sin AME, mientras que las enzimas APH (3') (14/52) y AAC (3') (10/52) se detectaron entre CI, uno de los cuales produce APH (3') y AAC (6')-I simultáneamente. Conclusión: La resistencia a los aminoglucósidos está presente entre los aislados de E. coli en Brasil, pero en menor grado en los aislados ambientales. Se debe implementar la vigilancia de la resistencia a los antimicrobianos para monitorear las infecciones por E. coli resistentes a los aminoglucósidos.

SUMÁRIO Introdução: Escherichia coli é encontrada em vários ambientes e causa doenças em humanos. Os aminoglicosídeos são antimicrobianos que exibem atividade contra espécies Gram-negativas. No entanto, o uso indiscriminado desses compostos tem selecionado microrganismos resistentes, principalmente devido à produção de enzimas modificadoras de aminoglicosídeos (EMA). Material e métodos: A concentração inibitória mínima de aminoglicosídeos contra isolados de E. coli recuperadas de amostras clínicas (IC, n=52) e de águas residuais sanitárias (AR, n=33) foi determinada pelo método de microdiluição, de acordo com o European Committee on Antimicrobial Susceptibility Testing. A presença de EMA foi determinada com base no perfil de suscetibilidade à amicacina, gentamicina, canamicina e tobramicina, de acordo com Mancini et al. (2019). Resultados: 33,3% dos ARS e 100% dos ICs apresentaram resistência à amicacina, gentamicina ou neomicina. Os isolados produtores de enzima beta-lactamase de espectro estendido (23/27, 85%) mostraram resistência à gentamicina e/ou neomicina e resistência à amicacina foi observada simultaneamente apenas em um IC. Todos os ARs foram considerados de tipo selvagem sem EMA, enquanto as enzimas APH (3') (14/52) e AAC (3') (10/52) foram detectadas entre os ICs, um dos quais produz APH (3') e AAC (6')-I simultaneamente. Conclusão: A resistência aos aminoglicosídeos está presente entre isolados clínicos de E. coli no Brasil, mas em menor grau em isolados ambientais. Assim a vigilância da resistência antimicrobiana deve ser implementada para monitorar infecções por E. coli resistentes aos aminoglicosídeos.

Benefits of D-005, a lipid extract from Acrocomia crispa fruits, in the prevention of acute kidney njury induced by nephrotoxicity in rats / Benefícios do D-005, um extrato lipídico de frutos da Acrocomia crispa, na prevenção de lesão renal aguda induzida por nefrotoxicidade em ratos

Abstract Introduction: Aminoglycoside-induced acute kidney injury (AKI) is a pathology closely linked to oxidative and inflammatory reactions. Taking into account the previous reported antioxidant and anti-inflammatory effects of D-005, a lipid extract obtained from Cuban palm Acrocomia crispa (Arecaceae) fruits, this work aimed to evaluate the effects of D-005 on kanamycin-induced AKI. Methods: Male Wistar rats were divided into 7 groups: negative control (vehicle, Tween 65/H2O) and six groups treated with kanamycin to induce AKI: positive control (vehicle), D-005 (25, 100, 200, and 400 mg/kg) and grape seed extract (GSE, 200 mg/kg). D-005, vehicle, and GSE oral treatments were administered once daily for seven days, 1 h before kanamycin (500 mg/kg, i.p.). Serum uric acid and urea concentrations, renal histopathology, and oxidative markers (malondialdehyde (MDA), sulfhydryl (SH) groups, and catalase (CAT) activity) were assessed. Results: D-005 significantly reduced uric acid and urea levels, starting from D-005 100 mg/kg. Histopathologically, D-005, at all the tested doses, protected renal parenchyma structures (glomeruli, proximal tubules, and interstitium). These findings were accompanied by a significant reduction of MDA and SH group concentrations as well as restoration of CAT activity. The highest percentages of inhibition were obtained with the dose of 400 mg/kg. GSE, the reference substance, also prevented kanamycin-induced biochemical and histopathological changes, as well as reduced MDA and SH groups and restored CAT activity. Conclusion: The administration of repeated oral doses of D-005 significantly protected against kanamycin-induced AKI, which could be associated with the antioxidant and anti-inflammatory effects of this extract.

Resumo Introdução: Lesão renal aguda induzida por aminoglicosídeos é uma patologia intimamente ligada a reações oxidativas e inflamatórias. Considerando efeitos antioxidantes e anti-inflamatórios relatados anteriormente do D-005, um extrato lipídico de frutos da palmeira cubana Acrocomia crispa (Arecaceae), este trabalho avaliou efeitos do D-005 na LRA induzida por canamicina. Métodos: Dividiu-se ratos Wistar machos em 7 grupos: controle negativo (veículo, Tween 65/H2O) e seis grupos tratados com canamicina para induzir LRA: controle positivo (veículo), D-005 (25, 100, 200, 400 mg/kg) e extrato de semente de uva (ESU, 200 mg/kg). D-005, veículo, e tratamentos orais com ESU foram administrados uma vez por dia durante sete dias, 1 h antes da canamicina (500 mg/kg, i.p.). Avaliou-se concentrações séricas de ácido úrico e ureia, histopatologia renal e marcadores oxidativos (malondialdeído (MDA), grupos sulfidrila (SH), atividade de catalase (CAT)). Resultados: D-005 reduziu significativamente níveis de ácido úrico e ureia, partindo de D-005 100 mg/kg. Histopatologicamente, D-005, em todas as doses testadas, protegeu estruturas do parênquima renal (glomérulos, túbulos proximais e interstício). Estes achados foram acompanhados por uma redução significativa das concentrações de MDA e grupo SH, e pela restauração da atividade CAT. As maiores porcentagens de inibição foram obtidas com a dose de 400 mg/kg. ESU, a substância de referência, também evitou alterações bioquímicas e histopatológicas induzidas por canamicina, reduziu MDA e grupos SH e restaurou atividade CAT. Conclusão: A administração de doses orais repetidas de D-005 protegeu significativamente contra LRA induzida por canamicina, que pode estar associada aos efeitos antioxidantes e anti-inflamatórios deste extrato.

Determination of 7 aminoglycoside antibiotics residues in bear bile powder by mix-mode SPE-hydrophilic interaction liquid chromatography tandem mass spectrometry / 药学学报

An analytical method was developed for determination of 7 aminoglycosides antibiotics in bear bile powder by hydrophilic interaction liquid chromatography tandem mass spectrometry. The samples were purified by mix-mode weak cation exchange and reversed-phase SPE. Waters ACQUITY UPLC BEH Amide column (100 mm × 3.0 mm, 1.7 μm) was used with 0.2% formic acid aqueous solution-0.2% formic acid acetonitrile solution as mobile phases by gradient elution. The aminoglycosides were detected by electrospray ionization mass spectrometry in positive mode with multiple reaction monitoring (MRM) mode. Spectinomycin, streptomycin, amikacin, kanamycin, tobramycin, apramycin and neomycin possessed good linear correlation in the respective concentration ranges, with the correlation coefficients more than 0.99. The mean recoveries at 3 spiked levels were in the range of 61.3%～127.3%, and the RSDs were 0.1%～1.9%. The limits of quantification were 0.2～1.0 mg·kg-1. The method had been applied to the analysis of actual samples.

Role of aminoglycoside-modifying enzymes and 16S rRNA methylase (ArmA) in resistance of Acinetobacter baumannii clinical isolates against aminoglycosides

Abstract INTRODUCTION: This study aimed to determine the role of genes encoding aminoglycoside-modifying enzymes (AMEs) and 16S rRNA methylase (ArmA) in Acinetobacter baumannii clinical isolates. METHODS: We collected 100 clinical isolates of A. baumannii and identified and confirmed them using microbiological tests and assessment of the OXA-51 gene. Antibiotic susceptibility testing was carried out using disk agar diffusion and micro-broth dilution methods. The presence of AME genes and ArmA was detected by PCR and multiplex PCR. RESULTS: The most and least effective antibiotics in this study were netilmicin and ciprofloxacin with 68% and 100% resistance rates, respectively. According to the minimum inhibitory concentration test, 94% of the isolates were resistant to gentamicin, tobramycin, and streptomycin, while the highest susceptibility (20%) was observed against netilmicin. The proportion of strains harboring the aminoglycoside resistance genes was as follows: APH(3′)-VIa (aphA6) (77%), ANT(2")-Ia (aadB) (73%), ANT(3")-Ia (aadA1) (33%), AAC(6′)-Ib (aacA4) (33%), ArmA (22%), and AAC(3)-IIa (aacC2) (19%). Among the 22 gene profiles detected in this study, the most prevalent profiles included APH(3′)-VIa + ANT(2")-Ia (39 isolates, 100% of which were kanamycin-resistant), and AAC(3)-IIa + AAC(6′)-Ib + ANT(3")-Ia + APH(3′)-VIa + ANT(2")-Ia (14 isolates, all of which were resistant to gentamicin, kanamycin, and streptomycin). CONCLUSIONS: High minimum inhibitory concentration of aminoglycosides in isolates with the simultaneous presence of AME- and ArmA-encoding genes indicated the importance of these genes in resistance to aminoglycosides. However, control of their spread could be effective in the treatment of infections caused by A. baumannii.

Transition of Determination Method of Potency of Neomycin Sulfate from Microbiological Assay to HPLC-PAD / 中国药学杂志

OBJECTIVE: To establish a high performance liquid chromatography combined with pulsed amperometric detection(HPLC-PAD)method for determination of potency of neomycin sulfate. METHODS: An improved HPLC-PAD method from EP method for determination of the content and related substances of neomycin sulfate was established and validated. The study of impurity profile of neomycin sulfate was completed by LC-IT-TOF method with the help of on-line desalination using a suppressor; and the main components in neomycin sulfate were clarified combining the RESULTS of impurity profile and minimum inhibitory concentrations of the main components and impurities. The semi-preparative liquid chromatography-evaporative light scattering detector(ELSD) was self-assembled, highly purified neomycin B and neomycin C were prepared and their structural confirmation was also conducted. The contents of highly purified neomycin B and neomycin C were determined by means of mass balance method. The potencies of highly purified neomycin B and neomycin C were determined by three-dose antibiotic microbial assay and the conversion factors between contents of neomycin B and neomycin C and their potencies were calculated separately and then a formula for the calculation of potency of neomycin sulfate from the content of main components of neomycin B and neomycin C was obtained.At last, a verification experiment for the accuracy of the conversion factor and the formula were designed and a serial of tests were carried out to investigate the interaction and the verification for the actual sample. RESULTS: The improved HPLC-PAD method was superior to the European Pharmacopoeia method in the separation ability and stability, and was suitable for accurate quantification of various components of neomycin sulfate and related substance inspection. The successful removal of trifluoroacetic acid in the mobile phase by the technology of desalination on-line using a suppressor broke a new way for the study of impurity profile of aminoglycoside such as neomycin sulfate. Combining the impurity profile with the RESULTS of MIC it was clarified that the main activity components of neomycin sulfate were neomycin B and neomycin C. Highly purified neomycin B and neomycin C were successfully prepared. A conversion factor for the transition from potency to purity of neomycin sulfate was obtained through experiments and calculations and was verified successfully. CONCLUSION: It is feasible to replace the microbial assay by HPLC-PAD method for determining the potency of neomycin sulfate.

Investigation of carbapenemases and aminoglycoside modifying enzymes of Acinetobacter baumannii isolates recovered from patients admitted to intensive care units in a tertiary-care hospital in Brazil

Abstract INTRODUCTION: Acinetobacter baumannii are opportunistic bacteria, highly capable of acquiring antimicrobial resistance through the production of carbapenemases and aminoglycoside modifying enzymes (AMEs). METHODS: Carbapenemase and AME genes were investigated in A. baumannii recovered from inpatients of a Brazilian hospital. RESULTS: The key genes found were bla OXA-51-like, the association ISAba1- bla OXA-23-like, and the AME genes aph(3´)-VI, aac(6´)-Ib, aac(3)-Ia, and aph(3´)-Ia. Different clusters spread through the institution wards. CONCLUSIONS: The dissemination of bla OXA-23-like and AME-carrying A. baumannii through the hospital highlights the need for improved preventive measures to reduce the spread of infection.

Detection of high-level aminoglycoside resistance by disc diffusion and e-test amongst the enterococcus species isolated from various clinical samples in a tertiary care hospital

Background: The emergence of Enterococcus species in causing nosocomial infections poses a therapeutic challenge to clinicians. Enterococci are intrinsically resistance to multiple antibiotics. Acquired resistance to commonly used antibiotics like Ampicillin, Vancomycin and Aminoglycosides have made the situation worse and difficult to treat serious Enterococcal infections. The present study aimed at detection of high-level aminoglycoside resistance by disc diffusion and E-test amongst the Enterococcus species isolated from various clinical samples in a tertiary care hospital.Methods: A total of 102 Enterococcus species isolated from various clinical samples and antimicrobial susceptibility was performed by Kirby Bauer disc diffusion method as per CLSI guidelines. E-test was done for all high level aminoglycoside resistance Enterococcus species isolated by disc diffusion test.Results: Among 102 isolates, 81 were E. faecalis, 18 were E. faecium and 3 were another Enterococcus. Their antimicrobial susceptibility pattern shows all isolates were sensitive to vancomycin, linezolid and teicoplanin with HLGR, HLSR detected in 40 and 38 isolates of E. faecalis, 17  and 13 isolates of E. faecium respectively by disc diffusion whereas by E-test it was detected in 44 and 40 in E. faecalis and 17 and 14 in E. faecium respectively. E. faecium is found to be more resistance to high level aminoglycoside than E. faecalis.Conclusions: Authors hereby conclude that Enterococci being the common cause of hospital acquired infections with their increasing resistance to multiple drugs and acquisition of HLAR; it must be routinely screened for various drugs to prevent drug resistance in hospital settings for serious Enterococcal infections.

Diverse aminoglycoside phosphotransferase types conferring aminoglycoside resistance in Enterobacteriaceae: A single-centre study from Northeast India

The present study investigates the molecular basis of aph-mediated aminoglycoside resistance and their transmission dynamics in a tertiary care hospital of Northeast India. Two hundred forty one isolates (230 Escherichia coli and 11 Klebsiella pneumoniae) were collected and screened for aminoglycoside resistance genes. Various aph types were amplified using polymerase chain reaction (PCR) assay. Plasmid incompatibilty, horizontal transferability and ERIC-PCR based typing were carried out for all the positive isolates. Among them, 67 isolates showed the presence of aph gene. Aph (3“)-IIIa and aph (3')-Via were predominant and horizontally transferable. All the plasmids were of incompatibility I1 group. Twenty-eight different haplotypes of E. coli were found harbouring aph gene types. This study was able to identify diverse aph types in a single centre and their corresponding phenotypic trait.

Emergence of aph(3')-VI and accumulation of aminoglycoside modifying enzyme genes in KPC-2-possessing Enterobacter aerogenes isolates from infections and colonization in patients from Recife-PE, Brazil

Abstract INTRODUCTION: The objective of this study was to characterize genes of aminoglycoside modifying enzymes (AMEs) in colonizing and infecting isolates of E. aerogenes harboring bla KPC from patients at a public hospital in Recife-PE, Brazil. METHODS: We analyzed 29 E. aerogenes clinical isolates resistant to aminoglycosides. AMEs genes were investigated by PCR and sequencing. RESULTS: Colonizing and infecting isolates mainly presented the genetic profiles aac(3)-IIa/aph(3')-VI or ant(2")-IIa/aph(3')-VI. This is the first report of aph(3')-VI in E. aerogenes harboring bla KPC in Brazil. CONCLUSIONS: The results highlight the importance in establishing rigorous methods for the surveillance of resistance genes, especially in colonized patients.

ArmA and RmtB Were the Predominant 16S RMTase Genes Responsible for Aminoglycoside-resistant Isolates in Korea

Pathogenic gram-negatives that produce 16S ribosomal RNA methyltransferases (16S RMTases) have already been distributed all over the world. To investigate the predominance of aminoglycoside resistance associated with 16S RMTases in Korea, we collected a total of 222 amikacin resistant Gram-negative clinical isolates from patient specimens between 1999 and 2015 from three hospital banks across Korea. ArmA and rmtB were the predominant 16S RMTase genes responsible for aminoglycoside-resistant isolates circulating in Korean community settings although only one rmtA-producing isolate was detected in 2006.

The importance of audiometric monitoring in patients with multidrug-resistant tuberculosis

Abstract INTRODUCTION: A total of 771 cases of multidrug-resistant tuberculosis (MDR-TB) were reported in Brazil in 2014. Treatment of MDR-TB with aminoglycosides can produce serious side effects such as permanent and irreversible hearing loss, which occurs in 5-64% of cases, and severely compromise patient quality of life. The goal of this research was to evaluate auditory and vestibular side effects in patients treated for MDR-TB and to identify associations between these complaints and the type of aminoglycoside used. METHODS: We performed a retrospective review of 599 medical records from patients with MDR-TB who were treated at the Hélio Fraga/Fiocruz Reference Center between 2006 and 2010. Cases without auditory or vestibular complaints and patients who were not treated with aminoglycoside drugs were excluded from the study. RESULTS: Of 164 eligible cases, 55 (33.5%) reported an auditory or vestibular complaint and medication was subsequently suspended, although hearing damage was not confirmed in all cases. Audiometric testing confirmed hearing loss in 11 (21.7%) of 12 cases submitted for evaluation. Hearing loss related to ototoxicity was confirmed in 15 (62.5%) cases. Tinnitus was significantly associated with the use of amikacin and streptomycin. CONCLUSIONS: Evaluations of ototoxicity symptoms were not usually reported in the routine care of patients with MDR-TB. Complaints of tinnitus were associated with amikacin and streptomycin use. These results require confirmation in future studies.

Advances in the Components Analysis of Aminoglycosides / 中国药学杂志

This paper first briefly introduces the basic information of aminoglycosides for pharmaceutical use such as origin, classification, chemical structures, diversity of composition and the research originators, etc. Then it reviews the development process of the technologies for the analysis of components of aminoglycosides, discusses the advantages and disadvantages of current methodologies and explains the advantage of liquid chromatography coupled with pulsed amperometric detection method for analysis of the components of aminoglycosides. At last, it introduces some new analysis technologies and ideas and forecasts the direction of future development.

Study on the aminoglycoside resistance gene of nosocomial multidrug-resistant Acinetobacter baumannii / 国际检验医学杂志

Objective To investigate the prevalence of aminoglycoside resistance gene in multidrug-resistant Acinetobacter bau-mannii isolated in clinical at a certain time,and to provide the basis for the control of nosocomial infection.Methods 9 strains of multidrug-resistant Acinetobacter baumannii were isolated in First People′Hospital of Weifang from November 26,2013 to Decem-ber 12,2013.Identification of bacteria and susceptibility testing were conducted by VITEK2,and partial antimicrobial drug suscepti-bility tests were performed by the disk diffusion method.Aminoglycoside resistance genes were detected by PCR and the positive genes were partly sequenced.Results Among the 9 stains of multidrug-resistant Acinetobacter baumannii,2 strains carried aac(3)-Ⅰ gene,3 carried ant(3″)-Ⅰ gene,3 carried aac(6′)-Ⅰ gene.AndarmA gene was positive in 9 strains.All strains were resistant to aminoglycosides,such as amikacin,gentamicin and tobramycin.There were 5 specien issolated in ICU,while 3 specimens were isola-ted in neurosurgery ward.All specimens were separated from sputum.Conclusion Antimicrobial resistance to aminoglycosides of Acinetobacter baumannii isolated in the hospital during this time was related to aminoglycoside resistance gene.Nosocomial infec-tion caused by multidrug-resistant Acinetobacter baumanniiin,ICU and neurosurgery ward should be vigorously monitored.

The prevalence of aminoglycoside-modifying enzyme and virulence genes among enterococci with high-level aminoglycoside resistance in Inner Mongolia, China

ABSTRACT This study highlights the prevalence of aminoglycoside-modifying enzyme genes and virulence determinants among clinical enterococci with high-level aminoglycoside resistance in Inner Mongolia, China. Screening for high-level aminoglycoside resistance against 117 enterococcal clinical isolates was performed using the agar-screening method. Out of the 117 enterococcal isolates, 46 were selected for further detection and determination of the distribution of aminoglycoside-modifying enzyme-encoding genes and virulence determinants using polymerase chain reaction -based methods. Enterococcus faecium and Enterococcus faecalis were identified as the species of greatest clinical importance. The aac(6')-Ie-aph(2")-Ia and ant(6')-Ia genes were found to be the most common aminoglycoside-modifying enzyme genes among high-level gentamicin resistance and high-level streptomycin resistance isolates, respectively. Moreover, gelE was the most common virulence gene among high-level aminoglycoside resistance isolates. Compared to Enterococcus faecium, Enterococcus faecalis harbored multiple virulence determinants. The results further indicated no correlation between aminoglycoside-modifying enzyme gene profiles and the distribution of virulence genes among the enterococcal isolates with high-level gentamicin resistance or high-level streptomycin resistance evaluated in our study.

Distribution of genes encoding aminoglycoside‑modifying enzymes among clinical isolates of methicillin‑resistant staphylococci.

The objective of this study was to determine the distribution of genes encoding aminoglycoside‑modifying enzymes (AMEs) and staphylococcal cassette chromosome mec (SCCmec) elements among clinical isolates of methicillin‑resistant staphylococci (MRS). Antibiotic susceptibility test was done using Kirby–Bauer disk diffusion method. The presence of SCCmec types and AME genes, namely, aac (6’)‑Ie‑aph (2’’), aph (3’)‑IIIa and ant (4’)‑Ia was determined using two different multiplex polymerase chain reaction. The most encountered AME genes were aac (6′)‑Ie‑aph (2’’) (55.4%) followed by aph (3’)‑IIIa (32.3%) and ant (4’)‑Ia gene (9%). SCCmec type I (34%) was predominant in this study. In conclusion, the aac (6’)‑Ie‑aph (2’’) was the most common AME gene and SCCmec type I was most predominant among the MRS isolates.

Identificación de genes que codifican enzimas modificadoras de aminoglucósidos en cepas intrahospitalarias de Klebsiella pneumoniae / Identification of genes encoding aminoglycoside-modifying enzymes of Klebsiella pneumoniae nosocomial isolates

Las infecciones por Klebsiella pneumoniae, constituyen un problema creciente en los centros hospitalarios. El objetivo de la presente investigación fue evaluar la resistencia a los aminoglucósidos, así como la presencia de genes que codifican enzimas modificadoras de aminoglucósidos (EMA) en aislados intrahospitalarios de Klebsiella pneumoniae. Se analizaron 56 cepas provenientes de pacientes con diagnóstico de infección intrahospitalaria del Hospital Universitario “Antonio Patricio de Alcalá”, durante el periodo enero-septiembre de 2008. Se determinó la susceptibilidad antimicrobiana mediante los métodos de difusión y dilución en agar, siguiendo los lineamientos del Instituto de Estándares Clínicos y de Laboratorio. Se empleó la técnica de la reacción en cadena de la polimerasa (PCR) para detectar los genes que codifican EMA. Se encontró resistencia a gentamicina y tobramicina en el 33,9% y 35,7%, respectivamente. Los fenotipos de resistencia a aminoglucósidos más frecuentes fueron I (ANGMKTob) y II (GMKTob). Se identificaron los genes aadA (21,4%), aac(3)-IIa (16,1%), aadB (14,3%), aac (6`)-Ib (3,6%) y aph (3`)-Ia (1,8%). En 10 cepas se observó la presencia de más de un gen y en 13 cepas se correlacionó el fenotipo con los genes encontrados. La resistencia a los aminoglucósidos en los aislados evaluados se debe, principalmente, a enzimas de tipo acetiltransferasas.

Klebsiella pneumoniae infection is a growing problem in hospitals. The objective of this study was to evaluate resistance to aminoglycosides and detection of genes encoding for aminoglycoside modifying enzymes (AME) in hospital isolates of K. pneumoniae. Fifty-six isolates from patients with diagnosis of nosocomial infection at the University Hospital Antonio Patricio de Alcala, during the period January to September 2008 were included for study. Antimicrobial susceptibility was determined by the methods of diffusion and agar dilution, following the Institute for Clinical and Laboratory Standards Guidelines. Genes encoding AME were determined by the polymerase chain reaction procedure. Resistance results for Gentamycin were 33.9% and for Tobramycin 35.7%. Aminoglycoside resistance phenotypes most frequently identified were I (ANGMKTob) and II (GMKTob). The genes involved were aadA (21.4%), aac(3)-IIa (16.1%), aadB (14.3%), aac (6`)-Ib (3.6%) y aph (3`)-Ia (1.8%) For 10 of the isolates studied more than one gene was identified. In 13 isolates the phenotype corresponded to the genes found. Aminoglycoside resistance in the isolates studied is mainly due to the presence of acetyltransferase enzymes.

Antimicrobial Susceptibility and Clonal Distribution of the Blood Isolates of Pseudomonas aeruginosa from Two Korean Hospitals

An increasing prevalence of infections caused by multidrug-resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa) causes a serious therapeutic problem in clinical setting. This study investigated the antimicrobial susceptibility, resistance mechanisms against aminoglycosides, and molecular epidemiology of 76 blood isolates of P. aeruginosa from two Korean hospitals. Thirty-four isolates were susceptible to all 13 antimicrobial agents tested, whereas 28 isolates showed a MDR or extensively drug-resistant phenotype. There was a significant difference in resistance rates of P. aeruginosa isolates against aztreonam, piperacillin-tazobactam, imipenem, meropenem, ciprofloxacin, and norfloxacin between two hospitals. Genes for aminoglycoside-modifying enzymes (AMEs), including aphA6 (n = 14), aadB (n = 11), aacA4 (n = 8), and aphA1 (n = 1), and 16S rRNA methylase armA (n = 6) were detected in 26 P. aeruginosa isolates resistant to aminoglycosides. There was no significant difference in carriage of genes for AME and 16S rRNA methylase between two hospitals, but aacA4 and aphA1 were specifically detected in P. aeruginosa isolates from one hospital. Seventy-six P. aeruginosa isolates were classified into 55 pulsotypes at similarity value of 0.85, and 31 and 24 pulsotypes were specifically detected in each hospital. This study demonstrates that differences in antimicrobial susceptibility of P. aeruginosa isolates between two hospitals are possibly due to the presence of diverse clones specific in each hospital.