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.

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.

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.

Genetic basis of high level aminoglycoside resistance in Acinetobacter baumannii from Beijing, China

The objective of this study was to investigate the genetic basis of high level aminoglycoside resistance in Acinetobacter baumannii clinical isolates from Beijing, China. 173 A. baumannii clinical isolates from hospitals in Beijing from 2006 to 2009 were first subjected to high level aminoglycoside resistance (HLAR, MIC to gentamicin and amikacin>512 µg/mL) phenotype selection by broth microdilution method. The strains were then subjected to genetic basis analysis by PCR detection of the aminoglycoside modifying enzyme genes (aac(3)-I, aac(3)-IIc, aac(6')-Ib, aac(6')-II, aph(4)-Ia, aph(3')-I, aph(3')-IIb, aph(3')-IIIa, aph(3')-VIa, aph(2″)-Ib, aph(2″)-Ic, aph(2″)-Id, ant(2″)-Ia, ant(3″)-I and ant(4')-Ia) and the 16S rRNA methylase genes (armA, rmtB and rmtC). Correlation analysis between the presence of aminoglycoside resistance gene and HLAR phenotype were performed by SPSS. Totally 102 (58.96%) HLAR isolates were selected. The HLAR rates for year 2006, 2007, 2008 and 2009 were 52.63%, 65.22%, 51.11% and 70.83%, respectively. Five modifying enzyme genes (aac(3)-I, detection rate of 65.69%; aac(6')-Ib, detection rate of 45.10%; aph(3')-I, detection rate of 47.06%; aph(3')-IIb, detection rate of 0.98%; ant(3″)-I, detection rate of 95.10%) and one methylase gene (armA, detection rate of 98.04%) were detected in the 102 A. baumannii with aac(3)-I+aac(6')-Ib+ant(3″)-I+armA (detection rate of 25.49%), aac(3)-I+aph(3')-I+ant(3″)-I+armA (detection rate of 21.57%) and ant(3″)-I+armA (detection rate of 12.75%) being the most prevalent gene profiles. The values of chi-square tests showed correlation of armA, ant(3″)-I, aac(3)-I, aph(3')-I and aac(6')-Ib with HLAR. armA had significant correlation (contingency coefficient 0.685) and good contingency with HLAR (kappa 0.940). The high rates of HLAR may cause a serious problem for combination therapy of aminoglycoside with β-lactams against A. baumannii infections. As armA was reported to be able to cause high level aminoglycoside resistance to most of the clinical important aminoglycosides (gentamicin, amikacin, tobramycin, etc), the function of aminoglycoside modifying enzyme gene(s) in A. baumannii carrying armA deserves further investigation.

aac(6')-Ⅰ b gene in drug-resistant strains of Pseudomonas aeruginosa / 中华临床感染病杂志

Objective To investigate the distribution of aminoglycoside modifying enzyme genes (AMEs) and 16S rRNA methylase genes in drug-resistant strains of Pseudomonas aeruginosa. Methods Twenty strains of drug-resistant Pseudomonas aeruginosa were isolated from sputum and wound secretion samples collected from the First People's Hospital of Huai' an in Jiangsu province. Eight AMEs [aac(3)-Ⅰ , aac(3)-Ⅱ, aac(6')-Ⅰb,aac(6')-Ⅱ, ant{2)-Ⅰ ,ant(3)-Ⅰ , ant(4')-Ⅰ , aph(3')-Ⅱb] and 6 16S rRNA methylase genes (armA, rmtA, rmtB, rmtC, rmtD, npmA) were analyzed by PCR and verified by DNA sequencing. Results Out of 20 strains of Pseudomonas aeruginosa, aac(6')-Ⅱ was positive in 8 strains (40.0% ) , ant2- Ⅰ in 8 strains (40.0% ) , aac(3)-Ⅱ in 5 strains (25.0% ) , aac(6')- Ⅰ b in 2 strains (10.0% ) and rmtB in 1 strains (5.0% ) , respectively. The rest 9 genes were not detected. Among 2 strains harboring aac(6')- Ⅰ b, DNA sequencing confirmed that 1 was aac(6')- Ⅰ b (the clssical type) and another was aac(6')- Ⅰ b-cr. Conclusion Gene aac(6')- Ⅰ b-cr exists in drug-resistant Pseudomonas aeruginosa, and it has modifying effect on both aminoglycosides and quinolones.

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).

Aminoglycoside-modifying Enzyme and 16S rRNA Methylase Gene Expressions in Acinetobacter baumannii / 中华医院感染学杂志

OBJECTIVE To understand aminoglycoside-modifying enzyme and 16S rRNA methylase gene expressions in Acinetobacter baumannii in Xinjiang region.METHODS 20 A.baumannii strains were isolated and test the anti-bacterial drug sensitivity.PCR methods were used to test aminoglycoside-modifying enzyme and 16S rRNA methylase gene.RESULTS From thirteen A.baumannii strains detected the aminoglycoside-modifying enzyme genes,the detection rate was 65%;in which aac(3)-Ⅰ gene was positive in 4 strains(20%),aac(3)-Ⅱ gene in 8 strains(40%),aac(6′)-Ⅰad gene in 4 strain(20%),ant(3″)-Ⅰ gene in 4 strain(20%),and ant(2″)-Ⅰ gene was positive in 1 strain(5%).The aac(6′)-Ⅰ b and aac(6′)-Ⅱ gens and were not detected;the 16S rRNA gene methylation was negative.CONCLUSIONS There are aminoglycoside-modifying enzyme genes existing in A.baumannii,no 16S rRNA methylase gene was detected in Xinjiang region.

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.

Drug-resistant Genes aadA4/5 and aph(3′)-Ⅰ Associated with Aminoglycosides Be Found Existing in Escherichia coli Isolated from ICU / 中华医院感染学杂志

OBJECTIVE To investigate the antibiotics resistance of Escherichia coli(ECO) and distrubtion of aminoglycoside-modifying enzymes and 16S RNA methylase genes in ICU.METHODS The samples of 20 ECO isolates were collected from Dec 2007 to Jun 2008 of patients in ICU.To determine the sensitivity to the 30 antibacterials K-B method was used and aminoglycoside-modifying enzymes and 16S RNA methylase genes were analyzed by polymerase chain reaction(PCR).RESULTS In among the 20 ECO isolates,8 strains carried aac(3)-Ⅱ(40%),3 carried aac(6′)-Ⅰb(15%) and ant(3″)-Ⅰ(15%),1 be found aph(3′)-Ⅰ(10%)and 13 be found aadA4/5 aminoglycoside-modifying enzymes genes,no strain carried 16S RNA methylase genes.CONCLUSIONS aac(3)-Ⅱ、aac(6′)-Ⅰb,ant(3″)-Ⅰ,aph(3′)-Ⅰ and aadA4/5 aminoglycoside-modifying enzymes genes exist in ECO widely,they should be the main cause inducing the high rate of drug-resistance to aminoglycosides.

Drug-resistance and Aminoglycoside Modifying Enzymes Genes in Acinetobacter baumannii Isolated from ICU / 中华医院感染学杂志

OBJECTIVE To investigate the drug-resistance and aminoglycoside modifying enzymes (AME) in Acinetobacter baumannii (ABA) isolated from ICU. METHODS K-B method was conducted to detect the sensitivity to 14 common antibiotics of 291 strains of ABA isolated from 2005 to 2007;PCR was used to detect AME genes of partial bacteria isolated in 2005. RESULTS The drug-resistance rates of 13 kinds of antibiotics were 33.0-91.8%,but cefoperazone/sulbactam was low (12.7%). The rate of amikacin,gentamicin and tobramycin was 41.2%,61.2% and 61.5%. Twenty-three ABA strains were AME gene positive from total 27 ABA strains and the total positive rate was 74.4%.We found 21 strains with aac(3)-Ⅰ (77.8%),23 strains with aac(6′)-Ⅰ (85.2%) and 23 strains with ant(3″)-Ⅰ (85.2%). Two strains were found to have 2 kinds of AME genes,21 strains had 3 kinds of AME genes. The rest of ABA strains had not AME genes. CONCLUSIONS ABA isolated from ICU has strong drug-resistance rate and a high carrier rate,it is a critical area of preventing and controlling hospital infection.

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.