RESUMEN
PURPOSE: Single doses of gentamicin have demonstrated clinical efficacy in the treatment of urogenital gonorrhea, but lower cure rates for oropharyngeal and anorectal gonorrhea. Formulations selectively enriched in specific gentamicin C congeners have been proposed as a less toxic alternative to gentamicin, potentially permitting higher dosing to result in increased plasma exposures at the extragenital sites of infection. The purpose of the present study was to compare the antibacterial activity of individual gentamicin C congeners against Neisseria gonorrhoeae to that of other aminoglycoside antibiotics. METHODS: Antimicrobial susceptibility of three N. gonorrhoeae reference strains and 152 clinical isolates was assessed using standard disk diffusion, agar dilution, and epsilometer tests. RESULTS: Gentamicin C1, C2, C1a, and C2a demonstrated similar activity against N. gonorrhoeae. Interestingly, susceptibility to the 1-N-ethylated aminoglycosides etimicin and netilmicin was significantly higher than the susceptibility to their parent compounds gentamicin C1a and sisomicin, and to any other of the 25 aminoglycosides assessed in this study. Propylamycin, a 4'-propylated paromomycin analogue, was significantly more active against N. gonorrhoeae than its parent compound, too. CONCLUSION: Selectively enriched gentamicin formulations hold promise for a less toxic but equally efficacious alternative to gentamicin. Our study warrants additional consideration of the clinically established netilmicin and etimicin for treatment of genital and perhaps extragenital gonorrhea. Additional studies are required to elucidate the mechanism behind the advantage of alkylated aminoglycosides.
Asunto(s)
Aminoglicósidos , Antibacterianos , Gentamicinas , Gonorrea , Pruebas de Sensibilidad Microbiana , Neisseria gonorrhoeae , Neisseria gonorrhoeae/efectos de los fármacos , Gentamicinas/farmacología , Antibacterianos/farmacología , Humanos , Aminoglicósidos/farmacología , Gonorrea/tratamiento farmacológico , Gonorrea/microbiología , Netilmicina/farmacologíaRESUMEN
Wound infection is one of the most important causes of morbidity and mortality worldwide. The aim of this study was to identify the organisms and their sensitivity pattern from wound infection patients attending in a tertiary care hospital in Dhaka city. This cross-sectional study was carried out in a total of 240 aseptically collected wound swab samples from wound infection suspected patients visiting Bangladesh Medical College Hospital, Dhaka, Bangladesh were analyzed from July 2017 to June 2019. Bacteriological culture of the samples, colony morphology, Gram's staining, and biochemical tests were done following standard microbiological techniques. The antimicrobial susceptibility testing was performed by modified Kirby-Bauer disc diffusion technique following clinical and laboratory standards institute guidelines. Out of 240 wound swab samples from suspected patients of wound infection, 126(52.5%) showed bacterial growth whereas 114(47.5%) were culture negative. No sample yielded more than one organism. Among 126 culture positive cases 75(59.52%) were male and 51(40.48%) were female. The higher rate of bacterial infections 26.19% was noted in the age group of 21-30 years, followed by the age group of 31-40 years, 41-50 years, 51-60 years. Among 126 culture positive cases, 74.6% were Gram negative and 25.4% were Gram positive bacteria. Out of total 126 isolates, E. coli was the most prevalent pathogen 31(24.60%) followed by Staphylococcus aureus 29(23.01%); Pseudomonas 27(21.43%); Klebsiella 18(14.29%); Enterobacter 12(9.52%); Acinetobacter 4(3.17%), while Coagulase negative Staphylococcus 3(2.38%) and Proteus 2(1.59%) were least detected isolates in wound swab. Highly effective antibiotics against Staph aureus were vancomycin 100.0%; imipenem 100.0%; linezolid 100.0% and meropenem 89.65%. Amikacin; gentamicin; netilmicin; imipenem and meropenem showed higher sensitivity in E coli, Klebsiella and Enterobacter species. Colistin was 88.88% effective against Pseudominas spp. followed by imipenem 81.48%, piperacillin-tazobactam 77.78%, meropenem 70.37% and amikacin 51.85%. Acinetobacter spp. showed 75.0% and 50.0% sensitivity to netilmicin and colistin respectively. Injectable and reserve drugs were sensitive to bacterial populations among patients of wound infections in our hospital. It is a wake-up call for clinician to treat wound infections. To prevent the increase resistance to antibiotics, it is necessary to avoid the administration of uncontrolled and unnecessary antibiotics available.
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Colistina , Infección de Heridas , Humanos , Masculino , Femenino , Adulto Joven , Adulto , Colistina/farmacología , Escherichia coli , Netilmicina/farmacología , Meropenem/farmacología , Amicacina/farmacología , Centros de Atención Terciaria , Estudios Transversales , Bangladesh/epidemiología , Antibacterianos/uso terapéutico , Antibacterianos/farmacología , Staphylococcus aureus , Pruebas de Sensibilidad Microbiana , Imipenem/farmacologíaRESUMEN
Plazomicin is currently the only next-generation aminoglycoside approved for clinical use that has the potential of evading the effects of widespread enzymatic resistance factors. However, plazomicin is still susceptible to the action of the resistance enzyme AAC(2')-Ia from Providencia stuartii. As the clinical use of plazomicin begins to increase, the spread of resistance factors will undoubtedly accelerate, rendering this aminoglycoside increasingly obsolete. Understanding resistance to plazomicin is an important step to ensure this aminoglycoside remains a viable treatment option for the foreseeable future. Here, we present three crystal structures of AAC(2')-Ia from P. stuartii, two in complex with acetylated aminoglycosides tobramycin and netilmicin, and one in complex with a non-substrate aminoglycoside, amikacin. Together, with our previously reported AAC(2')-Ia-acetylated plazomicin complex, these structures outline AAC(2')-Ia's specificity for a wide range of aminoglycosides. Additionally, our survey of AAC(2')-I homologues highlights the conservation of residues predicted to be involved in aminoglycoside binding, and identifies the presence of plasmid-encoded enzymes in environmental strains that confer resistance to the latest next-generation aminoglycoside. These results forecast the likely spread of plazomicin resistance and highlight the urgency for advancements in next-generation aminoglycoside design.
Asunto(s)
Acetiltransferasas/química , Antibacterianos/química , Proteínas Bacterianas/química , Farmacorresistencia Bacteriana/genética , Providencia/enzimología , Sisomicina/análogos & derivados , Acetiltransferasas/genética , Acetiltransferasas/metabolismo , Amicacina/química , Amicacina/metabolismo , Amicacina/farmacología , Antibacterianos/metabolismo , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sitios de Unión , Clonación Molecular , Cristalografía por Rayos X , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Humanos , Cinética , Modelos Moleculares , Netilmicina/química , Netilmicina/metabolismo , Netilmicina/farmacología , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Providencia/química , Providencia/efectos de los fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Sisomicina/química , Sisomicina/metabolismo , Sisomicina/farmacología , Especificidad por Sustrato , Tobramicina/química , Tobramicina/metabolismo , Tobramicina/farmacologíaRESUMEN
Acanthamoeba keratitis (AK) is a sight-threatening corneal infection. The early symptoms include redness, pain, photophobia and intense tearing. Chronic infection usually progresses to stromal inflammation, ring ulcers, corneal opacification and hypopyon. Here we document an AK case in a high myopic 38-year-old woman from Mexico City, with a history of wearing contact lenses while swimming. Corneal scrapes cultures were positive only for amoebae, consequently a treatment including netilmicin 0.3% and oral itraconazole 100 mg/12â¯h was prescribed. The infection was resolved after 8 months, leaving a slight leucoma outside the visual axis, with a visual acuity of 20/150. In the laboratory, the amoebic isolate was axenized in PYG medium, with an optimal growth at 30⯰C, and was identified morphologically as Acanthamoeba polyphaga according to the taxonomic criteria of Page (1988) and placed in the T4 group by genotyping. The virulence of this strain (40%) was determined by intranasal inoculation of 1â¯×â¯106/20⯵l trophozoites in BALB/c mice recovering from brain, proving their invasion ability and by the interaction with monolayers of epithelial cells of the established MDCK line of canine kidney origin (1:2 ratio of interaction), at 1, 3, 6, 8 and 24â¯h; trophozoites migrated to cell junctions inducing few lytic zones. In addition to the biological characterization, in vitro drug sensitivity tests were performed using chlorhexidine, itraconazole, netilmicin and voriconazole. Results revealed that voriconazole was the most effective compound. A. polyphaga remains as one of the most frequently isolated species producing AK. The treatment of AK case using netilmicin and oral itraconazole solved the disease, but the healing process was wide-ranging (8 months). The use of voriconazole and chlorhexidine may be an alternative treatment of future AK cases in Mexico.
Asunto(s)
Queratitis por Acanthamoeba/parasitología , Acanthamoeba/efectos de los fármacos , Antiinfecciosos/administración & dosificación , Acanthamoeba/aislamiento & purificación , Queratitis por Acanthamoeba/tratamiento farmacológico , Adulto , Animales , Antibacterianos/administración & dosificación , Antibacterianos/farmacología , Antiinfecciosos/farmacología , Antifúngicos/administración & dosificación , Antifúngicos/farmacología , Clorhexidina/farmacología , Lentes de Contacto/efectos adversos , Lentes de Contacto/parasitología , Perros , Femenino , Humanos , Concentración 50 Inhibidora , Itraconazol/administración & dosificación , Itraconazol/farmacología , Células de Riñón Canino Madin Darby , México , Ratones , Ratones Endogámicos BALB C , Midriáticos/administración & dosificación , Netilmicina/administración & dosificación , Netilmicina/farmacología , Pruebas de Sensibilidad Parasitaria , Fenilefrina/administración & dosificación , Tropicamida/administración & dosificación , Voriconazol/farmacologíaRESUMEN
INTRODUCTION: Aminoglycoside resistance (AR) is common in health care-associated methicillin-resistant Staphylococcus aureus (HA-MRSA). AR is most often associated with the production of antibiotic modifying enzymes: bidomain AAC(6')-Ie/APH(2â³)-Ia acetyltransferase and phosphotransferase, ANT(4')-Ia nucleotidyltransferase, and APH(3â³)-IIIa phosphotransferase. AIM: Determination of aminoglycoside sensitivity, presence of genes encoding enzymes, and molecular typing of HA-MRSA strains derived from patients hospitalized in surgical and transplantation wards. MATERIALS AND METHODS: Fifty-four HA-MRSA strains, isolated from various materials from patients in the surgical and transplantation wards of Warsaw's clinical hospital, hospitalized between 1991 and 2007. The MIC values of gentamicin-GEN/tobramycin-TOB/amikacin-AK/netilmicin-NET were determined by the E-test (CLSI/EUCAST). Genes mecA/aacA-aphD/aadD/aph(3â³)-IIIa were detected using PCR. SCCmec types were determined according to the Oliveira method and the sequence type (ST)/clonal complex (CC) by the MLST method. RESULTS: Of the isolates tested, 36 (66.7%) showed resistance to at least one aminoglycoside: TOB (57.4%), GEN (53.7%), AK (55.6%), NET (24.1%). The aacA-aphD gene was present in 29 MRSA-GEN-R (most often in combination with aadD, 15/29 or aph(3â³)-IIIa, 10/29); the aacA-aphD gene was the only determinant of resistance in 1 isolate. The AR variants mainly belonged to the CC8 clonal complex (ST239/247/241/254/8) and most frequently contained SCCmec type III (3A) cassettes. CONCLUSIONS: Resistance to at least one aminoglycoside was present in 66.7% of HA-MRSA and in more than 22% to all of them. The presence of the aacA-aphD gene was sufficient to express the resistance phenotype to GEN/TOB/AK/NET. Resistant isolates were closely related to each other.
Asunto(s)
Aminoglicósidos/farmacología , Antibacterianos/farmacología , Proteínas Bacterianas/efectos de los fármacos , Kanamicina Quinasa/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Amicacina/farmacología , Proteínas Bacterianas/aislamiento & purificación , Gentamicinas/farmacología , Unidades Hospitalarias , Hospitales , Humanos , Kanamicina Quinasa/aislamiento & purificación , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Netilmicina/farmacología , Nucleotidiltransferasas/efectos de los fármacos , Nucleotidiltransferasas/aislamiento & purificación , Proteínas de Unión a las Penicilinas/efectos de los fármacos , Proteínas de Unión a las Penicilinas/aislamiento & purificación , Estudios Retrospectivos , Infecciones Estafilocócicas , Tobramicina/farmacologíaRESUMEN
OBJECTIVE: The rapid emergence of drug resistant Leishmanial strains makes it imperative to continue the development of cheap and effective drugs against the parasite. Due to the absence of effective vaccines against leishmaniasis, current therapeutic measures exclusively rely on chemotherapy. Here we attempt, to identify novel antileishmanial from a list of known drugs determined from a previous bioinformatics study. Synergism between various drug combinations (involving netilmicin, suramin, paromomycin and curcumin) have been estimated to identify potent multidrug therapies to combat the disease. RESULTS: The drugs were screened against Leishmania promastigotes by utilizing the MTT assay and against intracellular amastigotes using murine Macrophage like tumor cell, RAW 264.7 as a host. In vitro drug interactions were tested for several drug combinations with a modified fixed ratio isobologram method against both Leishmania major and Leishmania donovani. This work reports the in vitro antileishmanial activity for the aminoglycoside netilmicin (for some Leishmania parasites) and the anti-trypanosomatid suramin. Synergism was also observed between paromomycin-suramin and netilmicin-curcumin.
Asunto(s)
Antiprotozoarios/farmacología , Evaluación Preclínica de Medicamentos/métodos , Sinergismo Farmacológico , Leishmania/efectos de los fármacos , Leishmaniasis/tratamiento farmacológico , Netilmicina/farmacología , Suramina/farmacología , Animales , Línea Celular Tumoral , RatonesRESUMEN
Previous studies have evaluated the action of gentamicin against Malassezia pachydermatis. The aim of this study was to evaluate in vitro susceptibility of M. pachydermatis to the aminoglycosides- gentamicin, tobramycin, netilmicin and framycetin. The minimum inhibitory concentration (MIC) of gentamicin was determined following methods M27-A3 microdilution and Etest® . The Etest® was used to determine the minimum inhibitory concentration (MIC) of the tobramycin and netilmicin. The Kirby-Bauer test was used to determine the antibiotic susceptibility to the framycetin. The MIC50 and MIC90 were 8.12 µg/mL and 32.5 µg/mL by microdilution method for gentamicin. The MIC50, determined by the Etest® , was 8 µg/mL for gentamicin and netilmicin and 64 µg/mL for tobramycin. The MIC90 was 16 and 32 µg/mL for gentamicin and netilmicin respectively. The MIC90 was outside of the detectable limits for tobramycin. To framycetin, 28 strains (40%) of the 70 M. pachydermatis isolates tested showed a diameter of 22 mm, 22 strains (31.42%) showed a diameter of 20 mm, 16 strains showed a diameter of ≤ 18 mm, and only 5.71% of the isolates showed a diameter of ≥ 22 mm. This study provides evidence of high in vitro activity of the aminoglycosides-gentamicin, tobramycin, netilmicin and framycetin against M. pachydermatis. For gentamicin Etest® showed similar values of MIC50 y MIC90 that the obtained by microdilution method. We considered Etest® method could be a good method for these calculations with aminoglycosides.
Asunto(s)
Aminoglicósidos/farmacología , Antifúngicos/farmacología , Malassezia/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Amicacina/análisis , Amicacina/farmacología , Aminoglicósidos/análisis , Gentamicinas/análisis , Gentamicinas/farmacología , Malassezia/crecimiento & desarrollo , Netilmicina/análisis , Netilmicina/farmacología , Tobramicina/análisis , Tobramicina/farmacologíaRESUMEN
Persisters are rare phenotypic variants of regular bacterial cells that survive lethal antibiotics or stresses owing to slowing down of their metabolism. Recently, we have shown that polyamine putrescine can upregulate persister cell formation in Escherichia coli via the stimulation of rpoS expression, encoding a master regulator of general stress response. We hypothesized that rmf and yqjD, the stationary-phase genes responsible for ribosome inactivation, might be good candidates for the similar role owing to their involvement in translational arrest and the ability to be affected by polyamines. Using reporter gene fusions or single and multiple knockout mutations in rpoS, rmf and yqjD genes, we show in this work that (i) E. coli polyamines spermidine and cadaverine can upregulate persistence, like putrescine; (ii) polyamine effects on persister cell formation are mediated through stimulation of expression of rpoS, rmf and yqjD genes; (iii) these genes are involved in persister cell formation sequentially in a dynamic fashion as cells enter the stationary phase. The data obtained in this work can be used to develop novel tools relying on a suppression of polyamine metabolism in bacteria to combat persister cells as an important cause of infections refractory to antibiotics.
Asunto(s)
Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Netilmicina/farmacología , Poliaminas/metabolismo , Farmacorresistencia Bacteriana , Escherichia coli/crecimiento & desarrollo , Proteínas de Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Viabilidad Microbiana/efectos de los fármacos , Mutación , Proteínas Ribosómicas/genética , Espermidina/metabolismo , Activación Transcripcional , Regulación hacia ArribaRESUMEN
Therapeutic resistance towards most of the current treatment regime by Acinetobacter baumannii has reduced the prescribing antibiotic pattern and option is being re-shifted towards more toxic agents including aminoglycosides. The present investigation aimed at to study various mechanisms towards aminoglycoside non-susceptibility in clinical isolates of A. baumannii. The bacteria were subjected to genetic basis assessment for the presence of aminoglycoside modifying enzymes (AME), 16S rRNA methylase encoding genes and relative expression of AdeABC and AbeM efflux pumps in relation to their susceptibility to five aminoglycosides. When isolates were subjected to typing by repetitive extragenic palindromic (REP) PCR, isolates could be separated into thirteen definite clones. The majority of isolates (94%) were positive for AME encoding genes. Possession of ant(2')-Ia correlated with non-susceptibility towards gentamicin, amikacin, kanamycin, tobramycin; while, presence of aph(3')-VIa attributed to resistance towards amikacin, kanamycin; possession of aac(3')-Ia allied with non-susceptibility to amikacin, tobramycin and presence of aac(3')IIa correlated with kanamycin non-susceptibility. Presence of armA was detected in 34.4%, 34.2%, 29.2%, 40.3%, and 64.2% of isolates showing non-susceptibility to gentamicin, amikacin, kanamycin, tobramycin and netilmicin, respectively. No isolates were found to carry rmtB or rmtC. Amikacin non-susceptibility in comparison to other aminoglycosides correlated with over production of adeB. Overall, the results represented a definitive correlation between presence of AME encoding genes as well as armA and resistance of A. baumannii towards aminoglycosides. On the other hand, the up-regulation of AdeABC and AbeM systems was found to have only the partial role in development of aminoglycoside resistance.
Asunto(s)
Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Aminoglicósidos/farmacología , Farmacorresistencia Bacteriana/genética , ARNt Metiltransferasas/genética , Acinetobacter baumannii/enzimología , Acinetobacter baumannii/aislamiento & purificación , Amicacina/farmacología , Distribución de Chi-Cuadrado , Gentamicinas/farmacología , Humanos , Irán , Kanamicina/farmacología , Netilmicina/farmacología , Reacción en Cadena de la Polimerasa , ARN Ribosómico 16S/genética , Tobramicina/farmacología , ARNt Metiltransferasas/aislamiento & purificaciónRESUMEN
Acinetobacter baumannii coccobacilli are dangerous to patients in intensive care units because of their multidrug resistance to antibiotics, developed mainly in the past decade. This study aimed to examine whether there is a significant correlation between the number of Pro-Ala repeats in the CAP01997 protein, the EmrA homologue of A. baumannii, and resistance to antibiotics. A total of 79 multidrug-resistant A. baumannii strains isolated from patients were analysed. Resistance to antibiotics was determined on Mueller-Hinton agar plates using the Kirby-Bauer disk diffusion method. The number of CCTGCA repeats encoding Pro-Ala repeats in CAP01997 was determined by PCR and capillary electrophoresis. The 3D models of CAP01997 containing Pro-Ala repeats were initially generated using RaptorX Structure Prediction server and were assembled with EasyModeller 4.0. The models were embedded in a model bacterial membrane based on structural information from homologous proteins and were refined using 100-ns molecular dynamics simulations. The results of this research show significant correlation between susceptibility to netilmicin, tobramycin and imipenem and the number of repeated Pro-Ala sequences in the CAP01997 protein, a homologue of the Escherichia coli transporter EmrA. Predicted structures suggest potential mechanisms that confer drug resistance by reshaping the cytoplasmic interface between CAP01997 protein and the critical component of the multidrug efflux pump homologous to EmrB. Based on these results, we can conclude that the CAP01997 protein, an EmrA homologue of A. baumannii, confers resistance to netilmicin, tobramycin and imipenem, depending on the number of Pro-Ala repeats.
Asunto(s)
Acinetobacter baumannii/genética , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana Múltiple/genética , Proteínas de la Membrana/genética , Infecciones por Acinetobacter , Acinetobacter baumannii/efectos de los fármacos , Ceftazidima/farmacología , Dipéptidos/genética , Humanos , Imipenem/farmacología , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Netilmicina/farmacología , Tobramicina/farmacologíaRESUMEN
This study investigated the changes in antibiotic resistance in recurrent Pseudomonas aeruginosa infections in chronic suppurative otitis media (CSOM). Its aim was to provide a treatment strategy for P aeruginosa infections in CSOM for the prevention of multidrug resistance. A case-control study was conducted in tertiary teaching hospitals in Korea. The experimental group included patients with recurrent P aeruginosa infection who had relapsed within 2 months after the successful control of a previous P aeruginosa infection. The control group consisted of patients with a P aeruginosa infection who had no history of such an infection. An antibiotic sensitivity test was performed for each culture. The proportion of recurrent P aeruginosa infection was 22.69% (98 of 432 cases). Drug resistance to amikacin, tobramycin, netilmicin, ciprofloxacin, and levofloxacin was significantly changed after recurrent infection. The fluoroquinolone strains seen in recurrent P aeruginosa showed high cross-resistance to other drugs. Antibiotic resistance of P aeruginosa in CSOM changed with recurrent infection.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Otitis Media Supurativa/tratamiento farmacológico , Infecciones por Pseudomonas/tratamiento farmacológico , Pseudomonas aeruginosa/efectos de los fármacos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Amicacina/farmacología , Estudios de Casos y Controles , Niño , Preescolar , Enfermedad Crónica , Ciprofloxacina/farmacología , Femenino , Humanos , Lactante , Levofloxacino/farmacología , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Netilmicina/farmacología , Otitis Media Supurativa/microbiología , Infecciones por Pseudomonas/microbiología , Recurrencia , República de Corea , Estudios Retrospectivos , Tobramicina/farmacología , Adulto JovenRESUMEN
We evaluated aminoglycoside resistance in 87 Acinetobacter baumannii strains isolated from four hospitals located in the North West region of Iran and typed them in sequence groups (SGs) using trilocus sequence-based scheme to compare their clonal relationships with international clones. Resistance toward aminoglycosides was assayed by minimum inhibitory concentration (MIC) and presence of aminoglycoside-modifying enzymes (AMEs), and ArmA-encoding genes were evaluated in different SGs. The majority of isolates belonged to SG1 (39%), SG2 (33.3%), and SG3 (12.6%), whereas the remaining ones were assigned to six novel variants of SGs. MIC determination revealed netilmicin as the most and kanamycin as the least active aminoglycosides against all groups. Among the varied SGs, isolates of SG2 showed more susceptibility toward all tested aminoglycosides. APH(3'')-VIa-encoding gene was predominant in SG1 (47%), SG2 (62%), and SG6-9 (100%). However, AAC(3')-Ia (100%) and ANT(2')-Ia (90.9%) were the dominant AMEs in SG3. There was significant association between harboring of aminoglycoside resistance genes and specific aminoglycosides: gene encoded by APH(3')-VIa was allied to resistance against amikacin and kanamycin, whereas ANT(2')-Ia was related to the resistance toward gentamicin and tobramycin in SG2. In SG1, tobramycin resistance was correlated with harboring of AAC(6')-Ib. Screening of armA demonstrated the presence of this gene in SG1 (58.8%), SG2 (10.3%), as well as SG3 (9%). Our results revealed definite correlation between the phenotypes and genotypes of aminoglycoside resistance in different clonal lineages of A. baumannii.
Asunto(s)
Infecciones por Acinetobacter/epidemiología , Acinetobacter baumannii/genética , Aminoglicósidos/farmacología , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana/genética , Metiltransferasas/genética , Infecciones por Acinetobacter/tratamiento farmacológico , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/clasificación , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/aislamiento & purificación , Amicacina/farmacología , Células Clonales , Expresión Génica , Frecuencia de los Genes , Genotipo , Gentamicinas/farmacología , Hospitales , Humanos , Irán/epidemiología , Kanamicina/farmacología , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Netilmicina/farmacología , Fenotipo , Filogenia , Tobramicina/farmacologíaRESUMEN
OBJECTIVES AND AIMS: Escherchia coli isolated, from urine samples were studied for their antibiotic susceptibility patterns, with special reference to the new antimicrobial compound fosfomycin and their correlation with various virulence factors. MATERIAL AND METHODS: The mid stream urine samples received in the department were processed and identification was done by using the standard culture and identification techniques. The antibiotic susceptibility testing was done by modified Kirby-Bauer disk diffusion and the disk diffusion method was used to confirm the ESBL, AmpC, MBL production by the UPEC. Various virulence factors like hemolysin, haemagglutinaton, gelatinase, siderophore production, biofilm formation, serum resistance and hydrophobicity were detected. RESULTS: Fosfomycin was found to be most effective agent (100%) against uropathogenic E.coli followed by netilmicin (89.5%). The least effective agents were ampiciilin and cotrimoxazole. Twenty nine percent (29%) isolates were found to be multi drug resistant (MDR). CONCLUSIONS: The testing of the newer therapeutic agents like fosfomycin will add on to therapeutics for UTI's.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Infecciones por Escherichia coli/microbiología , Fosfomicina/farmacología , Infecciones Urinarias/microbiología , Orina/microbiología , Escherichia coli Uropatógena/efectos de los fármacos , Ampicilina/farmacología , Biopelículas , Humanos , Pruebas de Sensibilidad Microbiana , Netilmicina/farmacología , Combinación Trimetoprim y Sulfametoxazol/farmacología , Escherichia coli Uropatógena/aislamiento & purificación , Factores de Virulencia/química , Factores de Virulencia/aislamiento & purificaciónRESUMEN
The present study was carried out to understand the clonal relationship using enterobacteriaceae repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) among metallo-ß-lactamase (MBL) producing multidrug resistant Pseudomonas aeruginosa isolates from burn victims and their susceptibility to commonly used anti-pseudomonal agents. In the present study 94 non-duplicate P. aeruginosa strains from the wound samples of burn patients were included. Identification of the isolates was done by biochemical methods and antibiotic sensitivity was done by disc diffusion method following CLSI (Clinical Laboratory Standard Institute) guidelines. By using imipenem (IPM)-EDTA disk diffusion/double disc synergy method carbapenem resistant organisms were tested for MBL. To define the clonal relationship ERIC-PCR was used. Of the 94 isolates, 18 (19.14%) were found resistant to IPM and MBL production was shown 11 (11.70%) by the IPM-EDTA disc diffusion method. From dendrogram of the ERIC-PCR profile four major clusters were obtained (A, B, C and D). Cluster B contained the majority of the isolates (6 strains 1, 4, 8, 9, 10 and 11). This study using ERIC-PCR of randomly collected isolates exhibits high genetic diversity which rules out cross contamination frequency.
Asunto(s)
Quemaduras/microbiología , Farmacorresistencia Bacteriana Múltiple , Variación Genética , Pseudomonas aeruginosa/enzimología , Pseudomonas aeruginosa/genética , beta-Lactamasas/metabolismo , Amicacina/farmacología , Antibacterianos/farmacología , Ceftazidima/farmacología , Ceftriaxona/farmacología , Cilastatina/farmacología , Ácido Clavulánico/farmacología , Colistina/farmacología , Pruebas Antimicrobianas de Difusión por Disco , Combinación de Medicamentos , Humanos , Imipenem/farmacología , Minociclina/análogos & derivados , Minociclina/farmacología , Netilmicina/farmacología , Ofloxacino/farmacología , Filogenia , Reacción en Cadena de la Polimerasa , Pseudomonas aeruginosa/efectos de los fármacos , TigeciclinaRESUMEN
The clinical isolates of Staphylococcus aureus (n = 102) were analyzed on sensitivity and to gentamicin, tobramicin, netimicin and amikacin. The disc diffusing technique was applied. The technique ofpolymerase chain reaction was applied to analyze all strains establishing presence in their genomes genes aac (6'-Ie/aph(2"), ant1, aac, ant(6)-Ia, aph (3')-IIIa and ant(4')-Ia coding amino-glycoside-modifying enzymes. The strains sensitive to amino-glycosides had no the given genes in genome. The genome of all strains resistant to amino-glycosides included no less than two of enumerated genes. The 100% correlation was established between phenotypic resistance of analyzed strains to amino-glycosides and availability in them of gene aac(6')-Ie/aph(2").
Asunto(s)
Acetiltransferasas/genética , Antibacterianos/metabolismo , Genes Bacterianos , Genoma Bacteriano , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/genética , Acetiltransferasas/metabolismo , Amicacina/metabolismo , Amicacina/farmacología , Antibacterianos/farmacología , Técnicas de Tipificación Bacteriana , Biotransformación , Pruebas Antimicrobianas de Difusión por Disco , Farmacorresistencia Bacteriana/genética , Dosificación de Gen , Expresión Génica , Genotipo , Gentamicinas/metabolismo , Gentamicinas/farmacología , Hospitales , Humanos , Netilmicina/metabolismo , Netilmicina/farmacología , Ortopedia , Fenotipo , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Federación de Rusia , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/patología , Infecciones Estafilocócicas/cirugía , Staphylococcus aureus/enzimología , Staphylococcus aureus/aislamiento & purificación , Tobramicina/metabolismo , Tobramicina/farmacologíaRESUMEN
This study was aimed to develop poly(dl-lactide-co-glycolide) (PLGA) nanoparticle of highly water soluble antibiotic drug, netilmicin sulfate (NS) with improved entrapment efficiency (EE) and antibacterial activity. Dextran sulfate was introduced as helper polymer to form electrostatic complex with NS. Nanoparticles were prepared by double emulsification method and optimized using 2(5-1) fractional factorial design. EE was mainly influenced by dextran sulfate: NS charge ratio and PLGA concentration, whereas particle size (PS) was affected by all factors examined. The optimized NS-loaded-NPs had EE and PS of 93.23 ± 2.7% and 140.83 ± 2.4 nm respectively. NS-loaded-NPs effectively inhibited bacterial growth compared to free NS. Sustained release protected its inactivation and reduced the decline in its killing activity over time even in presence of bronchial cells. A MIC value of 18 µg/mL was observed for NPs on P. aeruginosa. Therefore, NPs with sustained bactericidal efficiency against P. aeruginosa may provide therapeutic benefit in chronic pulmonary infection, like cystic fibrosis.
Asunto(s)
Antibacterianos , Fibrosis Quística/tratamiento farmacológico , Ácido Láctico , Nanopartículas/química , Netilmicina , Ácido Poliglicólico , Pseudomonas aeruginosa/crecimiento & desarrollo , Antibacterianos/química , Antibacterianos/farmacocinética , Antibacterianos/farmacología , Línea Celular , Fibrosis Quística/microbiología , Humanos , Ácido Láctico/química , Ácido Láctico/farmacocinética , Ácido Láctico/farmacología , Netilmicina/química , Netilmicina/farmacocinética , Netilmicina/farmacología , Ácido Poliglicólico/química , Ácido Poliglicólico/farmacocinética , Ácido Poliglicólico/farmacología , Copolímero de Ácido Poliláctico-Ácido PoliglicólicoRESUMEN
BACKGROUND: Escherichia coli is considered as the most common cause of urinary tract infection (UTI) and acquired multiple resistances to a wide range of antibiotics such as aminoglycosides. Enzymatic alteration of aminoglycosides (AMEs) by aminoglycoside- modifying enzymes is the main mechanism of resistance to these antibiotics in E. coli. The aim of this study was detection and investigation of frequency of genes encoding aminoglycoside modifying enzymes (aac(3)-IIa and ant(2'')-Ia) in UPEC isolated from hospitalized patients in teaching hospital of Tehran, Iran. FINDINGS: A total of 276 UPEC were obtained from Urine samples in a hospital from Tehran. Antibiotic susceptibility to aminoglycosides was determined by disk diffusion method according CLSI guidelines in UPEC isolates. MICs of target antibiotics were determined by agar dilution method. All isolates were screened for the presence of the AMEs genes using the PCR. The results of disk diffusion showed 21%, 24.6%, 23.18%, 3.62% and 6.15% of isolates were resistant to Gentamicin, Tobramycin, Kanamicin, Amikacin and Netilmicin respectively. The agar dilution's results (MICs) were high, 66.19% for Gentamicin. The aac (3)-IIa and ant(2â³)-Ia genes were detected in (78.87%) and 47.88% of isolates respectively. CONCLUSIONS: This study shows the high frequency of genes encoding (AMEs) aac(3)-IIa and ant(2")-Ia genes and their relationship between different aminoglycoside resistance phenotypes.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana/genética , Regulación Bacteriana de la Expresión Génica , Frecuencia de los Genes , Genes Bacterianos , Escherichia coli Uropatógena/genética , Amicacina/farmacología , Pruebas Antimicrobianas de Difusión por Disco , Infecciones por Escherichia coli/tratamiento farmacológico , Infecciones por Escherichia coli/microbiología , Gentamicinas/farmacología , Hospitales de Enseñanza , Humanos , Irán , Kanamicina/farmacología , Netilmicina/farmacología , Tobramicina/farmacología , Infecciones Urinarias/tratamiento farmacológico , Infecciones Urinarias/microbiología , Escherichia coli Uropatógena/efectos de los fármacos , Escherichia coli Uropatógena/enzimología , Escherichia coli Uropatógena/aislamiento & purificaciónRESUMEN
Persisters are suggested to be the products of a phenotypic variability that are quasi-dormant forms of regular bacterial cells highly tolerant to antibiotics. Our previous investigations revealed that a decrease in antibiotic tolerance of Escherichia coli cells could be reached through the inhibition of key enzymes of polyamine synthesis (putrescine, spermidine). We therefore assumed that polyamines could be involved in persister cell formation. Data obtained in our experiments with the polyamine-deficient E. coli strain demonstrate that the formation of persisters tolerant to netilmicin is highly upregulated by putrescine in a concentration-dependent manner when cells enter the stationary phase. This period is also accompanied by dissociation of initially homogenous subpopulation of persister cells to some fractions differing in their levels of tolerance to netilmicin. With three independent experimental approaches, we demonstrate that putrescine-dependent upregulation of persister cell formation is mediated by stimulation of rpoS expression. Complementary activity of putrescine and RpoS results in ~ 1000-fold positive effect on persister cell formation.
Asunto(s)
Aminoglicósidos/farmacología , Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Netilmicina/farmacología , Putrescina/metabolismo , Tolerancia a Medicamentos , Escherichia coli/crecimiento & desarrollo , Viabilidad Microbiana/efectos de los fármacos , Putrescina/análisis , Espermidina/análisis , Espermidina/metabolismoRESUMEN
Stenotrophomonas maltophilia IOMTU250 has a novel 6'-N-aminoglycoside acetyltransferase-encoding gene, aac(6')-Iak. The encoded protein, AAC(6')-Iak, consists of 153 amino acids and has 86.3% identity to AAC(6')-Iz. Escherichia coli transformed with a plasmid containing aac(6')-Iak exhibited decreased susceptibility to arbekacin, dibekacin, neomycin, netilmicin, sisomicin, and tobramycin. Thin-layer chromatography showed that AAC(6')-Iak acetylated amikacin, arbekacin, dibekacin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin, and tobramycin but not apramycin, gentamicin, or lividomycin.
Asunto(s)
Antibacterianos/farmacología , Stenotrophomonas maltophilia/efectos de los fármacos , Stenotrophomonas maltophilia/enzimología , Acetiltransferasas/genética , Acetiltransferasas/metabolismo , Dibekacina/análogos & derivados , Dibekacina/farmacología , Farmacorresistencia Bacteriana Múltiple , Pruebas de Sensibilidad Microbiana , Neomicina/farmacología , Netilmicina/farmacología , Sisomicina/farmacología , Tobramicina/farmacologíaRESUMEN
It is known that aminoglycoside antibiotics bind well to melanin biopolymer, but the relation between their affinity to melanin and ototoxicity is not well established. The aim of this work was to examine the impact of netilmicin on melanogenesis in cultured normal human melanocytes (HEMa-LP). The WST-1 assay was used to detect netilmicin cytotoxic effect. Netilmicin induced concentration-dependent loss in melanocytes viability. The value of EC50 was found to be - 75.0 mM. The analyzed antibiotic inhibited melanin biosynthesis in a concentration-dependent manner. Increasing the drug concentration resulted also in a decrease of cellular tyrosinase activity. Netilmicin-induced modulation of melanogenesis in melanocytes in vitro may explain a potential role of melanin and melanocytes in the mechanisms of aminoglycosides ototoxic effects in vivo.