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.

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.

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.

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.

Prevalence of resistance to aminoglycosides and fluoroquinolones among Pseudomonas aeruginosa strains in a University Hospital in Northeastern Poland

The present study was conducted to investigate the prevalence of genes encoding resistance to aminoglycosides and fluoroquinolones among twenty-five Pseudomonas aeruginosa isolated between 2002 and 2009. In PCR, following genes were detected: ant(2")-Ia in 9 (36.0%), aac(6')-Ib in 7 (28.0%), qnrB in 5 (20.0%), aph(3")-Ib in 2 (8.0%) of isolates.

Aminoglycoside-resistant genes in Klebsiella pneumoniae / 中华临床感染病杂志

ObjectiveTo investigate the prevalence of 16S rRNA methylase genes, aminoglycoside modifying enzymes (AMEs) genes and small multidrug resistance efflux pump gene smr-2 in Klebsiella pneumoniae. MethodsTotally 138 Klebsiella pneumoniae isolates were collected in the First Affiliated Hospital, college of medicine, Zhejiang University from January 2007 to December 2009. Polymerase chain reaction (PCR) and DNA sequencing were performed to screen the presence of six 16S rRNA methylase genes ( rmtA, rmtB, rmtC, rmtD, armA and npmA), seven AMEs genes[aac ( 3 )- Ⅰ , aac ( 3 )- Ⅱ,aac(6′)- Ⅰ b, aac(6′)-Ⅱ, ant(2″)- Ⅰ , ant(3″)- Ⅰ , aph(3′)-Ⅵa]and small multidrug resistance efflux pumps gene (smr-2).Results Thirteen (9. 4％) isolates were found to carry rmtB gene, whereas 87 (63.0％) isolates were found to carry at least one kind of AMEs genes but no smr-2 was detected. The positive rates of aac(3)-Ⅱ, aac(6′)- Ⅰ b, ant (3″)- Ⅰ and ant(2″)- Ⅰ were 40.6％ (56/138), 31.9％ (44/138), 28.3％ (39/138) and 2.2％ (3/138), respectively. All strains harboring rmtB gene carried one to three AMEs genes. Among 44 aac(6′)- Ⅰ b positive strains, 37 (84. 1％ ) were confirmed to carryaac(6′)- Ⅰ b-cr. ConclusionFor Klebsiella pneumoniae, rmtB is the predominant subtype in 16S rRNA methylase genes, accompanying with several AMEs genes.

Expressions of aminoglycoside modifying enzymes genes in extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolates / 中华临床营养杂志

Objective To investigate the expressions of aminoglycoside modifying enzymes (AMEs)genes of extended-spectrum β-lactamase-producing Klebsiella pneumoniae (ESBL-KP) isolates in our hospital, with an attempt to provide evidence for rational clinical antibiotics use. Mothods A total of 42 strains of ESBL-KP were isolated from January 2007 to January 2008 in our hospital The expressions of 9 AMEs including aac (3)-Ⅰ , aac (3)-Ⅱ , aac (3)-l, aac (3)-Ⅳ, aac (6')- Ⅰ , aac (6')-Ⅰ, apb (3')-Ⅵ, ant (3")-Ⅰ, and ant (2") -Ⅰ were identified by polymerase chain reaction. Results The positive rates of aac (3) - Ⅱ, ant (3") - Ⅰ ,aac (6') - Ⅰ , apb (3') -Ⅵ, and aac (3) - Ⅰ were 85. 7%, 59. 5%, 21.4% , 9. 5%, and 7. 1% , respectively. All the other genotypes were negative. The positive rate of AMEs reached 90. 5% (38 of 42). Conclusions The expression rates of AMEs genes are high among ESBL-KP isolates in our hospital. The aminoglycoside resistance may be relevant with AMEs.

Thiry-nine Types of Resistant-related Genes in a Pan-resistant Alcaligenes xylosoxidans subsp xylosoxidans in Sputum from a Severe Chronic Hepatitis Patient / 中华医院感染学杂志

OBJECTIVE To study 39 kinds of resistant-related genes in a pan-resistant Alcaligenes xylosoxidans subsp xylosoxidans(AXXxx) in the sputum isolated from a severe hepatitis B patient.METHODS The susceptibility to antimicrobial agents were detected by MIC.16S rRNA and 39 resistant-related genes including 29 ?-lactamases genes,6 aminoglycoside-modifying enzymes(AMEs)genes,1 chlorhexidine-sulfadiazine resistant gene(qacE△1-sul1)and 3 intergron genes separated(intⅠ1,2,3) an AXXxx strain in the sputum of a severe hepatitis B patient were measured by PCR,and verified by DNA sequencing.RESULTS Among the strains,7 kinds of resistant-related genes(blaTEM-116,blaCARB-8,aac(6′)-Ⅱ,aac(3)-Ⅱ,ant(3″)-Ⅰ,qacE△1-sul1,and intI1)detected out.But other 27 kinds of ?-lactamases genes,3 kinds of AMEs(aac(6′)-Ⅰb,aac(3)-Ⅰ,ant(2″)-Ⅰ) genes,and 2 kinds of intⅠ(intⅠ2 and intⅠ3) genes were negative.CONCLUSIONS The pan-resistant A.xylosoxidans,mainly relates to 7 kinds of resistant-related genes(blaTEM-116,blaCARB-8,aac(6′)-Ⅱ,aac(3)-Ⅱ,ant(3″)-Ⅰ,qacE△1-sul1,and intⅠ1).

Forty Types of Resistant-related Genes in a Pan-resistant Pseudomonas aeruginosa / 中华医院感染学杂志

OBJECTIVE To study 40 kinds of resistant-related genes in a pan-resistant Pseudomonas aeruginosa.METHODS To detect the susceptibility of antimicrobial agents by MIC,40 resistant-related genes including 29 ?-lactamases genes,porin oprD2 genes,6 aminoglycoside-modifying enzymes(AMEs)genes,chlorhexidine/sulfadiazine resistant gene(qacE△1-sul1)and intergron(intⅠ1,2,3),etc,form 1 strain of P.aeruginosa were measured by PCR,and verified by DNA sequencing.RESULTS In the strain,there were positive of 6 kinds of resistant-related genes(blaTEM,blaOXA10,aac(6′)-Ⅱ,aac(3)-Ⅱ,qacE△1-sul1 and intⅠ1),but without oprD2 genes.Twenty-seven kinds of ?-lactamases genes,4 kinds of AMEs(aac(6′)-Ⅰb,aac(3)-Ⅰ,ant(3″)-Ⅰ and ant(2″)-Ⅰ),and 2 kinds of intⅠ(intⅠ2 and intⅠ3) were negative.CONCLUSIONS The multi-resistant mechanisms of pan-resistant P.aeruginosa are mainly related to 7 kinds of resistant-related genes(blaTEM,blaOXA10,oprD2,aac(6′)-Ⅱ,aac(3)-Ⅱ,qacE△1-sul1 and intⅠ1).

A Pan-resistant Burkholderia cenocepacia Strain in Sputum from a Severe Chronic Hepatitis Patient:Study of 39 types of Its Resistant-related Genes / 中华医院感染学杂志

OBJECTIVE To study 39 kinds of resistant-related genes in a pan-resistant Burkholderia cenocepacia(BCE) strain,in the sputum from a severe hepatitis B patient.METHODS To detect the susceptibility to antimicrobial agents by MIC,16S rRNA,39 resistant-related genes including 29 ?-lactamases genes,6 aminoglycoside-modifying enzymes(AMEs) genes,chlorhexidine/sulfadiazine resistant gene(qacE△1-sul1),integron(intⅠ1,2,3),et al,of 1 strain of BCE in the sputum from a severe hepatitis B patient,were measured by PCR,and verified by DNA sequencing.RESULTS The strain was BCE conformed by 16S rRNA-PCR-DNA sequencing.It was susceptible to ceftazidime,cefepime,ciprofloxacin,levofloxacin,and trimethoprim/sulfamethoxazole,but resistant to piperacillin,aztreonam,cefotaxime,cefoxitin,meropenem,imipenem,nitrofurantoin,gentamicin and amikacin.There were positive of 6 kinds of resistant-related genes(blaTEM-116,aac(6′)-Ⅰb,aac(3)-Ⅰ,ant(2″)-Ⅰ,ant(3″)-Ⅰ,and intⅠ1),28 kinds of ?-lactamases genes,2 kinds of AMEs genes(aac(6′)-Ⅱ and aac(3)-Ⅱ),2 kinds genes of intⅠ(intⅠ2 and intⅠ3) were negative.CONCLUSIONS The multi-resistant BCE is with its multiple resistant mechanisms,and mainly relates to 6 kinds of resistant-related genes(blaTEM-116,aac(6′)-Ⅰb,aac(3)-Ⅰ,ant(2″)-Ⅰ,ant(3″)-Ⅰ and intⅠ1.

Detection of Two Types of Aminoglycoside-modifying Enzymes Genes in Chryseobacterium spp / 中华医院感染学杂志

OBJECTIVE To study 6 kinds of aminoglycoside-modifying enzymes (AMEs) genes in Chryseobacterium spp isolates. METHODS The isolates were identified by API20NE Gram-negative identification cards,and the susceptibility of antimicrobial agents was detected by MIC kits ( bioM?rieux ) 6 AMEs genes of 2 strains of Chryseobacterium spp were measured by PCR,and verified by DNA sequencing and sequence analysis. RESULTS In the 2 strains,2 kinds of resistant genes [aac(6′)-Ⅱ and ant(2″)-Ⅰ] were positive,and 4 kinds genes of AMEs [aac (6′)-Ⅰb,aac(3)-Ⅱ,ant(3″)-Ⅰ and aac(3)-Ⅰ] were negative.The amplicons were purified,sequenced and analyzed with BLAST 2.0 and found to be identical to aac(6′)-Ⅱ and ant(2″)-Ⅰ. CONCLUSIONS There are AMEs in Chryseobacterium spp isolates. This is the first report on AMEs genes [coexistance of aac(6′)-Ⅱ and ant(2″)-Ⅰ] in Chryseobacterium spp.

Genotypes of Aminoglycoside-modifying Enzymes of Acinetobacter baumannii / 中华医院感染学杂志

OBJECTIVE To investigate the genotypes of aminoglycoside-modifying enzymes(AMEs)genes of Acinetobacter baumannii.METHODS Clinical isolates of A.baumannii were collected from 2003 to 2006,and their resistance to gentamicin,amikacin and tobramycin were tested by K-B method.Twenty-three isolates were chosen because of their resistance to aminoglycoside antibiotics(at least resistant to one kind of the drugs).Nine types of the AMEs were detected by PCR.RESULTS Drug resistant rates of 23 isolates of A.baumannii to gentamicin,amikacin and tobramycin,were 86.96%,56.5% and 69.56%,respectively.The detection rates of the 9 AMEs,including ant(3')-Ⅰ,aac(3)-Ⅰ、aac(6')-Ⅰ,aph(3')-Ⅵ,aac(3)-Ⅱ,aac(6')-Ⅱ and ant(2″)-Ⅰ were 69.56%,60.87%,56.52%,47.82%,30.4%,26.09% and 21.73%,respectively.CONCLUSIONS The resistance to aminoglycoside antibiotics of A.baumannii is mainly caused by AMEs.

Drug-resistant Genes Associated with Aminoglycosides in Acinetobacter baumannii Isolated from ICU / 中华医院感染学杂志

OBJECTIVE To investigate the antibiotic resistance of multi-resistant Acinetobacter baumannii(ABA) and distribution of aminoglycoside-modifying enzymes and 16S rRNA methylase genes in ICU in Yinzhou People′s Hospital in Ningbo. METHODS The samples of 20 ABA isolates were collected from Oct 2007 to Jul 2008 in ICU.K-B method was used to determine the sensitivity to 32 antibacterials and the aminoglycoside-modifying enzymes and 16S rRNA methylase genes were analyzed by polymerase chain reaction(PCR). RESULTS From 20 ABA isolates,8 strains carried aminoglycoside-modifying enzymes genes aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6′)-Ⅰb,and ant(3″)-Ⅰ,their positive rate was 10%,15%,30% and 25%,respectively;no strain carried 16S rRNA methylase genes. CONCLUSIONS The antibiotics resistance of A.baumannii is very serious in Yinzhou People′s Hospital in Ningbo.Aminoglycoside-modifying enzymes genes aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6′)-Ⅰb and ant(3″)-Ⅰ exist in multi-resistant A.baumannii widely.They would be the main causes of high drug-resistantce to aminoglycosides.

Analysis on 16S rRNA methylase genes and aminoglycoside modifying enzymes genes in Enterobacter cloacae in China / 中华流行病学杂志

Objective To investigate the 16S rRNA methylase genes and Aminoglycoside modifying enzymes(AMEs)genes in Enterobacter cloacae isolated from the People's Liberation Army 98th Hospital,Huzhou district,Zhejiang province,China.Methods 40 strains of Enterobacter cloacae were isolated from the inpatients between September,2003 and November,2004.5 kinds of 16S rRNA methylase gene (including armA,rmtA,rmtB,rmtC and rmtD)and 9 kinds of AMEs gene[including aac(3)-Ⅰ,aac(3)-Ⅱ,aac(3)-Ⅲ,aac(3)-Ⅳ,aac(6')-Ⅰ b,aac(6')-Ⅱ,ant(3'')-Ⅰ,ant(2'')-Ⅰ and aph(3')-Ⅵ]were analyzed by PCR and verificated by DNA sequencing.Results In 40 strains of Enterobacter cloacae,the positive rates of genes of rmtB,aac(3)-Ⅱ,aac(6')-Ⅰ b,ant(3'')-Ⅰ,ant(2'')-Ⅰ and aph(3')-Ⅵ were 12.5%(5/40),27.5%(11/40),72.5%(29/40),32.5%(13/40),5.0%(2/40)and 5.0%(2/40),respectively.8 kinds of the rest of genes were all tested negative.The total positive rate of AMEs gene was 85.0%(34/40).Among 29 strains of Enterobacter cloacae that the aac(6')-Ⅰ b gene was positive,through PCR and verification by DNA sequencing,7 strains(24.1%)were confirmed to take the aac(6')-Ⅰ b-cr(the GenBank register number:EF375620,EU159121)alone,18 strains(62.1%)were confirmed to take the aac(6')-Ⅰ b-Suzhou(EU085533)alone,3 strains(10.3%)were confirmed to take both aac (6')-Ⅰ b-Suzhou and aac(6')-Ⅰ b-cr while only 1(3.4%)was aac(6')-Ⅰ b(the classical type).Conclusion There was lower positive rate of 16S rRNA methylase gene but very high AMEs genotypes in Enterobacter cloacae isolated from inpatients and the finding of rmtB gene was reported for the first time in the world.At least 5 kinds of AMEs gene existed in Enterobacter cloacae were isolated and they were the new host of both gene of aac(6')-Ⅰ b-cr and aac(6')-Ⅰ b-Suzhou,with aac(6')-Ⅰ b-Suzhou gene was the predominance subtype in aac(6')-Ⅰ b.

New Genotypes for Aminoglycoside-modifying Enzymes in Escherichia coli / 中华医院感染学杂志

OBJECTIVE To study the prevalence of aac(6′)-Ⅰb with its subtypes,one kind of gene for aminoglycoside-modifying enzymes in Escherichia coli.METHODS DNA sequences were analyzed in those strains with aac(6′)-Ⅰb,compared to its family marked in NCBI.Thus,its subtypes were determined.RESULTS Four strains were classical on genotype,the other one with aac(6′)-Ⅰb-Cr,and the last one with a new subtype among the 6 strains of E.coli with aac(6′)-Ⅰb.CONCLUSIONS There exist at least 3 subtypes of aac(6′)-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in local strains of E.coli.Among those subtypes,the classical type is the main,accompanied by aac(6′)-Ⅰb-Cr and its new subtype.

Aminoglycoside Modifying Enzymes Genes of Multi-drug Resistant Acinetobacter baumannii:A Study of 20 Strains / 中华医院感染学杂志

OBJECTIVE To investigate the aminoglycoside modifying enzymes genes of multi-drug resistant Acinetobacter baumannii(MDR-ABA).METHODS The four kinds aminoglycoside modifying enzymes genes(aac(6′)-Ⅰad,aac(6′)-Ⅰb,aac(3)-Ⅰ,ant(3″)-Ⅰ) of 20 strains MDR-ABA were detected by PCR.RESULTS Among 20 MDR-ABA strains,12 strains of aac(3)-Ⅰ,15 strains of aac(6′)-Ⅰb,18 strains of ant(3″)-Ⅰwere positive,and aac(6′)-Ⅰad was negative.The new subtype aac(6′)-Ⅰad gene has not been found.CONCLUSIONS Twenty strains MDR-ABA aminoglycoside modifying enzymes genes are found in all the 20 MDR-ABA strains.The genotype is in accordance with antibiotics resistance.It can induce clone transmitting hospital infection.It is first time to study the aac(6′)-Ⅰad gene of A.baumannii in China.

Genotyping of ?-Lactamases and Aminoglycoside Modifying Enzymes Genes from Acinetobacter baumannii / 中华医院感染学杂志

OBJECTIVE To investigate the genotyping of ?-lactamases and aminoglycoside modifying enzymes on Acinetobacter baumannii isolated in Shaoxing. METHODS Thirty nine strains of A.baumannii were isolated from hospitalized patients,and drug-resistant genes were detected by PCR. RESULTS The detection rates of ?-lactamases coding genes of TEM and OXA-23 groups were 33.3% and 51.3%,The detection rates of aminoglycoside modifying enzymes coding genes of aac(3)-Ⅰ,aac(6′)-Ⅰ and ant(3″)-Ⅰ were 64.1%,64.1% and 74.4%,respectively.The others were not found in all 39 isolates tested. CONCLUSIONS The study showed that it is more serious for A.baumannii carrying ?-lactamases and aminoglycoside modifying enzymes coding genes in Shaoxing.

Study on the Genotyping of Aminoglycoside Modifying Enzymes Genes from Pan-drug Resistant Acinetobacter Baumannii / 医学研究杂志

Objective To investigate the genotyping of aminoglycoside modifying enzymes on Pan-drug resistant A..baumannii(PDRA)isolated.Methods The antibiotic susceptibility of 16 different antibiotics of A.baumannii were tested by K-B method,aminoglycoside modifying enzymes coding genes of A.baumannii were detected by PCR.Results The detection rates of OXA-23group were 41.8%and aminoglycoside modifying enzymes coding genes of aac(3)-Ⅰ,aac(6')-Ⅰand ant(3″)-Ⅰ were 64.1%,64.1% and 74.4%.Conclusions The study showed that it is more serious for PDRA carrying aminoglycoside modifying enzymes coding genes.

The Study on the Drug Resistance and Genofyping of Aminoglycoside-modifying Enzymes in ESBLs Positive Escherichia Coli / 医学研究杂志

Objective To investigate drug resistance,especially the resistance to aminoglycoside and the prevalence of the genes for aminoglycoside-modifying enzymes in Escherichia coli producing ESBLs.Methods VITEK-32 GNI+ cards and K-B methods were used to identify E.coli and detect the resistance to 18 kinds of antibiotics such as aminoglycoside and ?-lactams respectively in E.coli isolated from our hospital from January to December,2006.PCR method was used to detect the genes for aminoglycoside-modifying enzymes such as aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6')-Ⅰb,aac(6')-Ⅱ,ant(3″)-Ⅰ and ant(2″)-Ⅰ in those 17 strains producing ESBLs.Results Resistance rates were 100.0%,100.0%,41.6%,100.0%,69.5%,30.5%,98.2%,81.0%,81.0%,79.6%,79.2%,34.8%,15.4%,7.1%,7.9%,5.4% and 81.0% for ampicillin,ampicillin/sulbactam,aztreonam,cefazolin,cefepime,ceftazidime,ceftriaxone,ciprofloxacin,levofloxacin,gentamicin,tobramycin,amikacin,cifoxitin,nitrofurantoin,piperacillin/tazobactam,cefoperazone/sulbactam and co-trimoxazole respectively in E.coli producing ESBLs.No drug-resistant strain imepenem was found.Positive rate was 46.4% for ESBLs.Resistance rates were 52.9%(9/17),100.0%(17/17) and 100%(17/17) for amikacin,gentamycin and tobmycin respectively in those 17 strains producing ESBLs.The most genotype for aminoglycoside-modifying enzymes was aac(3)-Ⅱ(94.1%),the second was aac(6')-Ⅰb(35.3%).The positive rates of aac(3″)-Ⅰ and ant(2″)-Ⅰ were 11.8% and 5.9% respectively.of them,one strain was resistant to aminoglycoside on phenotype,but no genes mentioned above was detected.4strains were classical on genotype,one with aac(6')-Ⅰb-Cr,the other one with a new subtype among the 6 strains of E.coli with aac(6')-Ⅰb.Conclusions Drug resistance in E.coli is rather serious.Typically,E.coli producing ESBLs shows multi-drug resistance.Positive rate for aac(3)-Ⅱ takes the first place,followed by aac(6')-Ⅰb among the genes for aminoglycoside-modifying enzymes.Aac(3″)-Ⅰand ant(2″)-Ⅰ show both lower positive rates.Aac(3)-Ⅰ and aac(6')-Ⅱ were not found.There exist at least 3 sub-types of aac(6')-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in strains of E.coli.Among those sub-types,the classical type is the main,accompanied by aac(6')-Ⅰb-Cr and its new sub-type.

Genes of 16S rRNA Methylases and Aminoglycoside Modifying Enzymes in Strains Continuously Isolated from PAE in two Hospitals / 中华医院感染学杂志

OBJECTIVE To investigate the drug-resistance and the existence of genes in 16S rRNA methylases and aminoglycoside modifying enzymes in strains continuously isolated from Pseudomonas aeruginosa(PAE) in two hospitals of Jiangsu and Zhejiang Provinces.METHODS The drug-resistance of the strains continuously isolated from PAE was detected with K-B test,five kinds of genes in 16S rRNA methylases(rmtA,rmtB,rmtC,rmtD and armA) and six kinds of aminoglycoside modifying enzymes [aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6′)-Ⅰb,aac(6′)-Ⅱ,ant(3″)-Ⅰ and ant(2″)-Ⅰ] were detected by PCR.RESULTS The strains were just sensitive to cefoperazone/sulbactam,imipenem,meropenem and amikacin(hospital A:74.2%,80.0%,82.9% and 68.5%;hospital B:90.0%,50.0%,50.0% and 95.0%,respectively).There was a high rate in the drug-resistance to ?-lactamase medicines,ciprofloxacin and sulfamethoxazole co.Genes in 16S rRNA methylases were not detected from PAE strains in the two hospitals.CONCLUSIONS The rates of genes in aminoglycoside modifying enzymes detected from strains in continuously isolated from PAE are different in different hospitals.