Efficacy and safefy of Polymyxin B treatment for neutropenic patients suffering from refractory Gram-negative bacterial bloodstream infection / 中华血液学杂志

Objective: To assess the efficacy and safety of polymyxin B in neutropenic patients with hematologic disorders who had refractory gram-negative bacterial bloodstream infection. Methods: From August 2021 to July 2022, we retrospectively analyzed neutropenic patients with refractory gram-negative bacterial bloodstream infection who were treated with polymyxin B in the Department of Hematology of the First Affiliated Hospital of the Soochow University between August 2021 to July 2022. The cumulative response rate was then computed. Results: The study included 27 neutropenic patients with refractory gram-negative bacterial bloodstream infections. Polymyxin B therapy was effective in 22 of 27 patients. The median time between the onset of fever and the delivery of polymyxin B was 3 days [interquartile range (IQR) : 2-5]. The median duration of polymyxin B treatment was 7 days (IQR: 5-11). Polymyxin B therapy had a median antipyretic time of 37 h (IQR: 32-70). The incidence of acute renal dysfunction was 14.8% (four out of 27 cases), all classified as "injury" according to RIFLE criteria. The incidence of hyperpigmentation was 59.3%. Conclusion: Polymyxin B is a viable treatment option for granulocytopenia patients with refractory gram-negative bacterial bloodstream infections.

Master genes and co-expression network analysis in peripheral blood mononuclear cells of patients with gram-positive and gram-negative sepsis / 浙江大学学报·医学版

OBJECTIVE@#To investigate the functional pathways enriched and differentially expressed genes (DEGs) in peripheral blood mononuclear cells (PBMCs) of patients with gram-positive and gram-negative sepsis.@*METHODS@#Dataset GSE9960 obtained from NCBI GEO database containing PBMC samples from 16 non-infectious systematic inflammatory response syndrome (SIRS) patients, 17 gram-positive septic patients and 18 gram-negative septic patients were included in the study. Functional pathway annotations were conducted by gene set enrichment analysis and weighted gene co-expression network analysis. DEGs were filtered and master DEGs were then validated in PBMCs of gram-positive septic, gram-negative septic and non-infectious SIRS patients.@*RESULTS@#The enriched gene sets in gram-positive sepsis and gram-negative sepsis were significantly different. The results indicated the opposite co-expression networks in SIRS and gram-negative sepsis, and the entirely different co-expression networks in gram-positive and gram-negative sepsis. Furthermore, we validated that @*CONCLUSIONS@#The results indicate that there are differences in the mechanism and pathogenesis of gram-positive and gram-negative sepsis, which may provide potential markers for sepsis diagnosis and empirical antimicrobial therapy.

Distribution characteristics of pathogenic bacteria in infectious donors from organ donation after citizen's death and preventive strategies for renal transplant recipients: a single center experience / 器官移植

Objective To investigate the distribution characteristics of pathogenic bacteria in infectious donors from organ donation after citizen's death and preventive strategies for renal transplant recipients. Methods Clinical data of 412 donors and 803 recipients from organ donation after citizen's death were retrospectively analyzed. All donors underwent culture of airway secretions, urine, blood and renal lavage fluid. The incidence rate of infection, distribution and composition ratio of pathogenic bacteria of donors from organ donation after citizen's death were observed. The scores of all donors were evaluated according to the length of intensive care unit (ICU) stay for donors, the situation of abdominal trauma and the results of body fluid culture, etc. According to the score, the recipients received different infection prevention regimes. The incidence rate of donor-derived infection (DDI) and clinical prognosis of the recipients were analyzed. Results A total of 243 donors were diagnosed with infection in 412 donors from organ donation after citizen's death with an infection rate of 59.0%. In total, 456 strains of pathogenic bacteria were isolated, mainly derived from the airway secretions (71.7%). Gram-negative bacteria dominantly consisted of Klebsiella pneumoniae and acinetobacter baumannii. Gram-positive bacteria mainly included staphylococcus aureus and fungus mainly included yeast-type fungus. Three recipients (kidneys from 2 donors respectively) developed DDI with an incidence rate of 0.4%. Conclusions The infection rate of donors from organ donation after citizen's death is relatively high. It is effective to prevent the incidence of DDI by grading the risk of infection of donors and adopting rational preventive plan according to the score.

Surveillance of bacterial resistance in Yongzhou Central Hospital of Hunan in 2016 and 2017 / 中国感染与化疗杂志

Objective To investigate the susceptibility and resistance profile of clinical isolates in Hunan Yongzhou Hospital during 2016 and 2017. Methods Antimicrobial susceptibility testing was carried out according to a unified protocol using KirbyBauer method or automated systems. Results were analyzed according to CLSI 2016 breakpoints. Results A total of 6 354 clinical isolates were collected from January 2016 to December 2017, of which 4 876(76.7％)were gram-negative bacteria, and 1 478(23.3％)were gram-positive bacteria. The top five bacterial species were Escherichia coli(33.0％), Klebsiella(17.0％), Staphylococcus aureus(9.6％), Acinetobacter(8.6％), and Pseudomonas aeruginosa(7.4％). The prevalence of methicillin-resistant Staphylococcus aureus(MRSA)was 33.8％, and prevalence of methicillin-resistant coagulase negative Staphylococcus(MRCNS)was 76.2％. The resistance rates of methicillin resistant strains(MRSA and MRCNS)to most of the tested drugs were significantly higher than those of methicillin sensitive strains(MSSA and MSCNS). No vancomycin or linezolid resistant staphylococci were identified. The resistance rate of Enterococcus faecium to most antimicrobial agents was significantly lower than that of Enterococcus faecium. No enterococcal isolate was resistant to vancomycin or linezolid. The non-meningitis S. pneumoniae strains isolated from children showed slightly higher resistance rate to penicillin(20.8％)than the strains isolated from adults(13.3％). The prevalence of extended spectrum beta-lactamases(ESBLs)in Escherichia coli and Klebsiella pneumoniae was 48.0％ and 35.7％, respectively. Most Enterobacteriaceae strains were highly sensitive to carbapenem antibiotics, showing lower resistancerate(<4％). The prevalence of carbapenem-resistant Klebsiella pneumoniae was 18.8％, and the prevalence of carbapenem-resistant E. cloacae was 14.5％. The prevalence of Acinetobacter baumannii strain resistant to imipenem and meropenem was 76.4％ and 78.6％, respectively. Conclusions Bacterial resistance is still serious. It is necessary to strengthen the monitoring of bacterial resistance, infection control, and rational use of antibiotics.

Results of bacterial resistance surveillance in a Guangdong hospital during 2015-2017 / 中国感染与化疗杂志

Objective To investigate the susceptibility profile of clinical isolates in the First Affiliated Hospital of Guangzhou Medical University during 2015-2017. Methods Susceptibility test was carried out using Kirby-Bauer method or automated systems. Results were analyzed according to CLSI 2017 breakpoints. Results A total of 17 645 clinical isolates were isolated from January 2015 to December 2017, including 3 091(17.5％)gram positive and 14 554(82.5％)gram negative bacteria. Methicillinresistant S. aureus(MRSA)and coagulase-negative Staphylococcus(MRCNS)accounted for 50.7％ and 77.9％, respectively. No staphylococcal isolates were found resistant to vancomycin, teicoplanin or linezolid. E. faecalis strains showed much lower resistance rate to most drugs tested than E. faecium. Nine(0.8％)E. faecalis isolates were found resistant to vancomycin. A total of 227 strains of the non-meningitis S. pneumoniae were tested, 44.1％ of which were isolated from adults and 55.9％ from children. Most of the S. pneumoniae isolated from adults and children were susceptible to penicillin(88.0％ and 81.1％, respectively). E. coli showed the highest proportion in three years. ESBLs were produced in 53.3％ of E. coli and 28.5％ of Klebsiella spp. A total of 255 strains of carbapenem-resistant Enterobacteriaceae(3.7％), 665 strains of carbapenem-resistant Pseudomonas aeruginosa(26.2％)and 900 strains of carbapenem-resistant Acinetobacter baumannii(57.5％)were identified. The annual change of prevalence was insignificant. A total of 141 strains of extensively-drug resistant Pseudomonas aeruginosa(5.6％)and 458 strains of extensively-drug resistant A. baumannii(29.3％)were identified, showing decreasing prevalence from 2015 to 2017. Conclusions The bacterial resistance in this hospital is relatively stable in the past three years, but it is still necessary to strengthen hospital infection control and management, and maintain good practice in surveillance of bacterial resistance.

Antimicrobial resistance profile of clinical isolates in hospitals across China: report from the CHINET Surveillance Program, 2017 / 中国感染与化疗杂志

Objective To investigate the antimicrobial resistance profile of the clinical isolates collected from selected hospitals across China. Methods Twenty-nine general hospitals and five children's hospitals were involved in this program. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were interpreted according to CLSI 2017 breakpoints. Results A total of 190 610 clinical isolates were collected from January to December 2017, of which gram negative organisms accounted for 70.8％ (134 951/190 610) and gram positive cocci 29.2％ (55 649/190 610). The prevalence of methicillin-resistant strains was 35.3％ in S. aureus (MRSA) and 80.3％ in coagulase negative Staphylococcus (MRCNS) on average. MR strains showed much higher resistance rates to most of the other antimicrobial agents than MS strains. However, 91.6％ of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 86.2％ of MRCNS strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains showed much lower resistance rates to most of the drugs tested (except chloramphenicol) than E. faecium. Vancomycin-resistant Enterococcus (VRE) was identified in both E. faecalis and E. faecium. The identified VRE strains were mainly vanA, vanB or vanM type based on phenotype or genotype. The proportion of PSSP or PRSP strains in the non-meningitis S.pneumoniae strains isolated from children decreased but the proportion of PISP strains increased when compared to the data of 2016. Enterobacteriaceae strains were still highly susceptible to carbapenems. Overall, less than 10％ of these strains (excluding Klebsiella spp.) were resistant to carbapenems. The prevalence of imipenem-resistant K. pneumoniae increased from 3.0％ in 2005 to 20.9％ in 2017, and meropenem-resistant K. pneumoniae increased from 2.9％ in 2005 to 24.0％ in 2017, more than 8-fold increase. About 66.7％ and 69.3％ of Acinetobacter (A. baumannii accounts for 91.5％) strains were resistant to imipenem and meropenem, respectively. Compared with the data of year 2016, P. aeruginosa strains showed decreasing resistance rate to carbapenems. Conclusions Bacterial resistance is still on the rise. It is necessary to strengthen hospital infection control and stewardship of antimicrobial agents. The communication between laboratorians and clinicians should be further improved in addition to surveillance of bacterial resistance.

Diagnostic value of procalcitonin in distinguishing Gram-negative bacterial blood stream infection from Gram-positive bacterial infection in early stage of sepsis / 中华急诊医学杂志

Objective To investigate the diagnostic values of procalcitonin (PCT),high sensitive C-reactive protein (hs-CRP),white blood cell (WBC)and percentage of neutrocyte (NEU％)in Gramnegative and Gram-positive bacterial blood stream infection in early stage of sepsis in order to investigate the correlation between PCT and APACHE lⅡ score as well as between PCT and SOFA score,and the prognostic value in assessment of Gram-negative and Gram-positive bacterial blood stream infection.Methods Clinical data of patients admitted to ICU from January 2012 through December 2014 were retrospectively analyzed.A total of 124 sepsis patients with blood stream infection were checked with PCT,hs-CRP,WBC and NEU％ tests,and APACHE Ⅱ score and SOFA score were calculated.The differences in APACHE Ⅱ score and SOFA score were compared between Gram-negative group (n =41) and Gram-positive group (n =83).The correlation between PCT and APACHE Ⅱ score as well as between PCT and SOFA score was analyzed.The differences in diagnostic values of PCT,hs-CRP,WBC and NEU％ between Gram-negative group and Grampositive group were analyzed by using receiver operating characteristic (ROC) curve and it was plotted to assess the prognostic values of PCT,hs-CRP,WBC and NEU％ for septic patients with blood stream infection.Results Compared with Gram-positive group,the levels of PCT [.55.32 (22.01,97.11) vs.2.13 (0.27,5.27)] (P ＜0.01),hs-CRP [105.09 (69.97,186.12) vs.70.54 (42.37,138.63)] (P=0.508),NEU％ [88.30 (75.79,93.52) vs.55.32 (22.01,97.11)] (P=0.302) were higher but WBC was lower [13.59 (10.74,17.58) vs.13.73 (11.32,20.90)] (P=0.058) in Gram-negative group.The ROC curve analysis of PCT showed the area under the curve (AUC) was 0.867 (95％ CI:0.789-0.946).When the optimal cutoff point of PCT was 17.48 ng/mL,the largest Youden's index was found to be 0.661 with 76.9％ sensitivity and 89.2％ specificity.Between two groups,there were significant differences in APACHE Ⅱ score and SOFA score (27.46 ± 9.60 vs.23.67 ± 7.74,P =0.020;8.05 ±3.38 vs.6.59-±3.45,P =0.028).There was significant difference in diagnostic value between PCT and SOFA (r =0.536,P =0.036) in Gram-negative group but no significant difference in Gram-positive group.Conclusions Higher PCT levels are found in Gram-negative group and it can play a role in differntiation between the Gram-negative group and Gram-positive group rather than hs-CRP,WBC and NEU％.PCT can be a better indicator for evaluation of severity of sepsis as well as for prognosis of sepsis patients with Gram-negative bacterium infection.

Bile-resistant Gram-negative bacteria effect of different kinds of root decoction pieces / 中国中药杂志

To investigate the microbial contamination in Chinese herbal decoction pieces with different functional types by studying the total aerobic microbial count (TAMC), and total yeast and mould count (TYMC) in 40 samples of 8 types of root decoction pieces; further evaluate the contamination load of bile-resistant Gram-negative bacteria, and identify the Gram-negative bacteria by using biochemical identification system for Gram-negative bacteria. Our results showed that the TAMC value was more than 1 000 CFU•g⁻¹ in 85% (34/40) samples, and was more than 100 CFU•g⁻¹ in 30% (12/40) samples; the contamination of bile-resistant Gram-negative bacteria was detected in 45% (18/40) of the samples. The bile-resistant Gram-negative bacteria load of seven batches of samples was N>1 000 MPN•g⁻¹. Sixteen bacterium strains including Serratia plymouthensis, Cedecea neteri, Escherichia vulneris, Klebsiella oxytoca, Enterobacter amnigenus, E. cloacae, E. sakazakii, Proteus penneri and E. gergoviae were obtained and identified. E. cloacae was the predominant bacterium that was isolated from Salviae Miltiorrhizae Radix et Rhizoma, while E. amnigenus, Yersinia pseudotuberculosis was the typical bacterium of Ophiopogonis Radix and Codonopsis Radix, respectively. All these suggested that the contamination of bile-resistant Gram-negative bacteria was severe for the root decoction pieces in Wuhan city. Microbial species have certain selection specificity for medicinal ingredients, so the type and limit of control bacteria for detection should be formulated according to the pollution type and quantity of bile-resistant Gram-negative bacteria.

Distribution and antimicrobial resistance of clinical gram-negative bacteria in the First Afifliated Hospital of Nanjing Medical University during 2014 / 中国感染与化疗杂志

Objective To investigate the distribution and antimicrobial resistance profile of clinical gram-negative bacterial isolates in the First Afifliated Hospital of Nanjing Medical University during 2014.Methods Bacteria identiifcation was performed by API system or the VITEK-2 Compact automatic identiifcation system. Disk diffusion susceptibility testing or VITEK-2 Compact automatic identification system was used to determine the susceptibility to antimicrobial agents. All data were analyzed using WHONET 5.6 software.Results Among the total 7 931 clinical isolates in 2014, gram-negative bacteria accounted for 64.2% (5 088/7 931). The top three pathogens wereE. coli,A. baumannii andK. pneumoniae. Notably, during the year 2014, 195 strains of carbapenem-resistantEnterobacteriaceaewere isolated, about 6.9% of all theEnterobacteriaceae isolates. Meanwhile, 613 (66.5%) strains of multiple drug resistantA. baumannii and 197 (28.7%) strains of multiple drug resistantP. aeruginosa were isolated.Conclusion During the year 2014, the resistance of the gram-negative bacteria in this hospital is mainly characterized by carbapenem-resistantEnterobacteriaceae, multiple drug resistant A. baumanniiand multiple drug resistantP. aeruginosa. Surveillance of antimicrobial resistance is beneifcial for rational use of antibiotics.

Perfil de sensibilidade de células sésseis e planctônicas de Escherichia coli a antimicrobianos usados no tratamento da mastite bovina / Sensitivity profile of planktonic and sessile cells of Escherichia coli to antimicrobial used in the treatment of bovine mastitis

Escherichia coli é um micro-organismo altamente adaptativo e sua habilidade em formar biofilmes pode ser fundamental na resistência a tratamentos com antimicrobianos. A avaliação da concentração mínima inibitória (CMI) vem sendo utilizada para verificar a sensibilidade dos micro-organismos aos antimicrobianos. Entretanto, quando se avaliam células sésseis, a concentração do antimicrobiano requerido para erradicação do biofilme é maior do que a determinada pela CMI. Objetivou-se comparar as CMI com as concentrações mínimas de erradicação de biofilmes (CMEB) de antimicrobianos usados no tratamento da mastite em 27 isolados de E. coli produtores de biofilmes provenientes de mastite. Os isolados foram submetidos a testes de sensibilidade a antimicrobianos usados no tratamento da mastite, tanto para células planctônicas, por meio da CMI, quanto para células sésseis, pela avaliação da CMEB. Os resultados revelaram uma alta sensibilidade: apenas quatro (14,8%) isolados obtiveram valores da CMI elevados, variando de 4 a 10µg/mL, sendo classificados como resistentes. Para os demais isolados (85,2%), os valores foram menores, variando de 0,125 a 2µg/mL, classificados como sensíveis. A avaliação de CMEB indicou que a concentração dos antimicrobianos necessária para eliminar as células sésseis variou de 100µg/mL a 500µg/mL. Os valores de CMEB foram significativamente maiores nos isolados grandes e moderados produtores de biofilmes em relação aos isolados fracos produtores de biofilmes (p<0,001). Não houve correlação entre os valores de CMEB e CMI (p>0,05). A escolha da terapêutica antimicrobiana correta para o tratamento de infecções intramamárias em bovinos relacionadas com a produção de biofilmes parece exigir a aplicação de testes mais específicos. Testes de susceptibilidade antimicrobiana baseados apenas em valores de CMI mostraram-se ineficazes em determinar com precisão a susceptibilidade das células bacterianas sésseis.

Escherichia coli is a highly adaptive microorganism. Its ability to form biofilms may be critical for resistance to antimicrobial treatments. Evaluation of minimum inhibitory concentration (MIC) has been used to check the sensitivity of microorganisms to antibiotics, however, when evaluating sessile cells, the required antibiotic concentration to eradicate biofilm is greater than determined by MIC. This study aimed to compare MIC with minimum biofilm eradication concentration (MBEC) of antimicrobials used in mastitis treatment in 27 E. coli biofilm producers isolates from mastitis. Isolates were tested for sensitivity to antimicrobials used in mastitis treatment, for both planktonic cells (by CMI) and sessile cells (by MBEC). The results revealed high sensitivity: only four (14.8%) isolates showed high MIC values, ranging from 4 to 10g/mL and they were classified as resistant. All other isolates (85.2%) showed lower values, ranging from 0.125 to 2mg/mL, and they were classified as sensitive. Evaluation of MBEC indicated that concentration of antimicrobial needed to remove sessile cells ranged from 100mg/mL to 500mg/mL. MBEC values were significantly higher in large and moderate biofilm producers isolates regarding weak biofilm producers isolates (p<0.001). There was no correlation between MBEC and CMI values (p>0.05). The correct choice of antimicrobial therapy for treatment of mammary infections in cattle related to biofilm production seems to require application of more specific tests. Antimicrobial susceptibility testing based only on MIC values proved ineffectiveness to accurately determination the susceptibility of sessile bacterial cells.

Metalo beta lactamasas: el fin de los beta lactámicos? / Metallo beta lactamases: the end of beta lactams?

Uno de los grupos de antibióticos más importantes, es el grupo de los beta-lactámicos. Para ejercer su acción antimicrobiana los beta-lactámicos requieren penetrar la pared celular y atacar las Proteínas Ligadoras de Penicilinas (Penicilin Binding Proteins: PBP). El mecanismo más utilizado por los bacilos Gram negativos para adquirir resistencia a beta-lactámicos, es la inactivación de las drogas por las enzimas beta-lactamasas. La producción de beta-lactamasas tipo carbapenemasas es un mecanismo de resistencia de gran importancia. Estas enzimas, codificadas por genes que en su mayoría están localizados en elementos genéticos tales como los integrones o insertados en elementos móviles como transposones y plásmidos, se han extendido rápidamente entre los agentes patógenos de importancia clínica, como Enterobacterias, P. aeruginosa y A. baumanii. Las metalo-beta-lactamasas (MbetaL) pertenecientes al grupo B de Ambler y el grupo 3 de Bush, poseen cuatro características principales: (i) Poseen actividad contra los carbapenemes, (ii) No hidrolizan los monobáctamicos como el aztreonam, (iii) Son inhibidas por quelantes como el EDTA o el Mercapto acetato de Sodio; y (iv) Requieren cationes +2 divalentes, generalmente Zn como cofactor para su actividad catalítica. La aproximación de un disco conteniendo un agente quelante a uno que contiene un carbapeneme podría resultar una herramienta útil para la detección de MbetaLs. El efecto sinérgico entre los carbapenemes [imipenem (IPM) y/o meropenem (MEN)] y el agente quelante sería indicativo de la presencia de MbetaL. La aparición de metalo-beta-lactamasas como una amenaza sustancial a la salud debe impulsar a las autoridades de salud para formular un plan de contención, para su implementación a nivel nacional. Este plan debe asegurar la detección temprana de casos, la vigilancia permanente de brotes y una estrategia en entornos con presencia espor dica o ausencia completa de productores metalo-beta-lactamasa.

One of the most important groups of antibiotics, is the group of beta-lactams. To exert its antimicrobial action the beta-lactam require penetrate and attack the cell wall Penicillin Binding Proteins (PBP). The mechanism used by Gram negative bacilli to acquire resistance tobeta-lactams, is drug inactivation by beta-lactamase enzymes. The production of beta-lactamase carbapenemases is a resistance mechanism of great importance. These enzymes encoded by genes that are located mostly in genetic elements such as integrons or inserted in mobile elements such as transposons and plasmids, have spread rapidly among clinically important pathogens such as Enterobacteriaceae, P. aeruginosa and A. baumannii. The metallo-beta-lactamases (MbetaL) in group B and group 3 Ambler Bush, have four main characteristics: (i) possess activity against carbapenems, (ii) not hydrolyze monobactams like aztreonam, (iii) are inhibited by chelating agents such as EDTA or sodium acetate Mercapto and (iv) require divalent cations, usually Zn+2 cofactor for its catalytic activity. The approximation of a disc containing a chelating agent containing one carbapeneme could be a useful tool for detecting MbetaLs. The synergistic effect between carbapenems [imipenem (IPM) and/or meropenem (MEN)] and the chelating agent would be indicative of the presence of MbetaL. The emergence of metallo-beta-lactamase as a substantial threat to health should prompt health officials to develop a plan of containment, for implementation at the national level. This plan should ensure early case detection, continuous surveillance of outbreaks and strategy in environments with sporadic presence or complete absence of metallo-beta-lactamase.

Detection of 16S rRNA methylase gene in gram-negative bacteria / 中国感染与化疗杂志

Objective To investigate the prevalence of 16S rRNA methylase genes, armA and rmtB, which mediate high level aminoglycoside resistance, in gram-negative bacteria isolated from 2 hospitals in Dalian and study the mechanism of aminoglycoside resistance.Methods A total of 134 amikacin-resistant clinical isolates of gram-negative bacteria were collected. Two 16S rRNA methylase genes, armA and rmtB, were identified by PCR-based assays. PCR products were extracted for DNA sequencing analysis. armA and rmtB gene mapping were conducted by plasmid extraction, conjugation and transformation. The MICs of amikacin, gentamicin and tobramycin were determined for the positive isolates, transconjugants and the resultant strain of transformation using agar dilution technique. Results Overall armA was identified in 21 strains of Acinetobacter baumannii, rmtB in 5 strains of Escherichia coli and 5 strains of Klebsiella pneumoniae. Plasmid extraction and conjugation experiments were only successful for rmtB-positive isolates. Transconjugant and DH5a (pMDarmA) exhibited high-level resistance to aminoglycosides.Conclusions The 16S rRNA methylase genes, armA and rmtB are identified in Dalian. armA gene is identified in A. baumannii. rmtB gene is located on the plasmid of E. coli and K. pneumoniae. armA and rmtB can induce high-level resistance to aminoglycosides.

Genotyping of AmpC Produced by Gram-negative in Infected Children / 中国药房

OBJECTIVE: To investigate the incidence rate of the ampC gene and AmpC enzyme of gram-negative(G-) bacterium in children,to analyze drug resistance of produced AmpC enzyme and un-produced AmpC enzyme strain.METHO_DS: 4 022 clinical G-isolates collected from 2002 to 2004 were identified and tested using K-B method.Selection 108 ESBLs bacterium,the ampC genes were amplified by PCR using common primers to AmpC and the AmpC enzymes were tested using the enzymatic rough extraction cefoxitin three-dimensional test.The drug resistance of bacterium produced AmpC enzymes were compared with the ones without AmpC enzymes.RESULTS: In 108 G-bacterium,the ampC genes positive bacterium were 70 strain(accounting for 64.8%),and 7 bacterium produced AmpC enzymes(accounting for 6.5%) were detected.The drug resistance of bacterium produced AmpC enzymes to ceftazidime(CAZ),ceftriaxone(CRO),piperacillin(PIP),ampicillin(AMP),aztreonam(ATM) were 85.7%,85.7%,71.4%,79.4%,79.4% respectively.The drug resistance of bacterium non-produced AmpC enzymes to CRO,PIP,gentamicin,AMP,ATM were 50.8%,55.6%,55.6%,70.3%,54.0% respectively,the drug resistance of bacterium to imipenem were the lowest,lower to ciprofloxacin.CONCLUSIONS: Detection rate of ampC gene were higher than AmpC-producing enzymes strains obviously,whereas the drug resistance to antibiotic of AmpC-producing enzymes strains were higher than non-producing enzymes strains.