| Objective In order to explore the Serratia marcescens enzyme production and in vitro antimicrobial activityagainst bacteria, explore the drug resistance, and drug combination mode in clinic treatment of enzyme producing bacteria infection and provide laboratory evidence. The testing of the first part of the Xianyang region(The Nuclear Industry 215 Hospital of Shaanxi, The First People’s Hospital of Xianyang City, Xianyang Hospital of Yan’an University) from 2009 January to 2012 December in clinical isolated 106 strains of Serratia marcescens from the characteristics and drug resistance of clinical infection sources, carries on the statistical analysis; the second part experiment, through the detection of ESBLs, Amp C enzyme and carbapenem enzymes, understanding the properties of enzyme producing region of Serratia marcescens, and in vitro combined chemosensitivity test of enzyme producing strain and selection of clinical commonly used antimicrobial agents, antibacterial activity assay characteristics of the combineddrugs on enzyme producing bacteria in vitro,dissemination of control and drug resistant strainsinfection of its clinical guidance to the important.Methods 1. The collection of Xianyang area(The Nuclear Industry 215 Hospital of Shaanxi, The First People’s Hospital of Xianyang City, Xianyang Hospital of Yan’an University) from 2009 January to 2012 December 一 n clinical isolated 106 strains of Serratia marcescens infection on the clinicalcharacteristics, distribution, antimicrobial resistance and intensive care unit and general ward analysis.ESBLs detection: in 106 strains of Serratia marcescens, producing ESBLs screening test of cefotaxime and ceftazidime, compound formulations and compared with combined withclavulanic acid, confirmatory test for ESBLs.2. ESBLs detection: in 106 strains of Serratia marcescens, producing ESBLs screening test of cefotaxime and ceftazidime, the resistance strains by double disk synergy test(confirmationof cefotaxime and cefotaxime/clavulanic acid, ceftazidime and ceftazidime/clavulanicacid) were used to detect ESBLs, resistance gene PCR detection of ESBLs producing strain.3. The detection of Amp C enzyme: screening test use of vinpocetine paper, and thenconfirmed by three-dimensional test. PCR detection of Amp C enzyme resistant gene.4. Detection of carbapenemases: application of the modified Hodge test on 8 strains ofcarbapenem resistant enzyme drug bacteria strains; KPC-Carbapenems resistant gene detected by PCR Technology.5. Combined chemosensitivity test: the checkerboard dilution method in vitro combined chemosensitivity test on enzyme production of Serratia marcescens, calculate FIC index,the effect of drug combination in vitro antibacterial activity of judgment.6. Statistical methods: using X2 test, if P<0.05 had statistical significance.Result 1. Source: isolated strains were obtained 106 strains of Serratia marcescens from Xianyang area, of which the most sputum samples, accounting for 84.1%(89/106), followed bysecretions, urine and throat swabs, were 4 strains, 3 strains, 3 strains; source of straindepartment mainly in intensive care unit(ICU) 41.5%(/106 44) strain 15.1%(16/106),respiratory department of internal medicine, Department of Neurosurgery, 13.2%(14/106)and 9.4%(10/106) of renal Department of internal medicine.2. The results of clinical drug sensitivity test of resistant:106 strains of Serratiamarcescens to the one or two generation cephalosporin rate was more than 90%;for the three or four generation cephalosporin resistance rate at around 20%;resistant to aminoglycosides,fluoroquinolones and carbapenem enzymes drug ratiois less than 10%.3. Drug resistance in intensive care unit and general ward strain rate results: resistance in intensive care unit and general ward were aztreonam 36.7% and 11.3%, 27.3% and 8.1%of cefepime, ceftazidime was 29.5% and 14.5%, Cefoperazone / sulbactam was 18.2% and 8.1%, 13.6% and 3.2% ertapenem, with 2 test, P<0.05, with statistical significance; and to ampicillin, cefazolin, cefuroxime, Amikacin, ciprofloxacin, piperacillin / tazobactam,imipenem, meropenem, resistance in intensive care unit and general ward rate respectivelywere analyzed by 2 test, P>0.05, no statistical difference.4. The positive rate of ESBLs producing: 106 strains of Serratia marcescens ESBLsscreening test positive rates of 34.9%(37/106), and 22 strains were resistant to ceftazidime, cefotaxime resistance in 31 strains, including 16 strains of bacteria to ceftazidime and cefotaxime and resistance; the double disc confirmatory test was positive in28 strains. The total positive rate was 26.4%(28/106). Detection of PCR gene resistant ESBLs application, there were 28 strains, the positive rate was 26.4%(28/106), 28 strains produced ESBL resistance gene strains, CTX-M type 75%(21/28), TEM type 46.4%(13/28), SHV type 10.7%(3/28), 16 strains of Serratia bacteria Sarre to produce two or more than two kinds drug resistant gene, 57.1%(16/28). 21 strains of CTX-M type beta lactamase strains, 5 were type CTX-M-1, which accounted for 23.8%(5/21); 8 were type CTX-M-2, which accounted for 38.1%(8/21); 15 were type CTX-M-9, which accounted for 71.4%(15/21).5. The positive rate of Amp C producing enzyme: Amp C enzyme positive rate of screening test of 21.7%(23/106), three dimensional confirmatory test was positive in 10 strains, the totalpositive rate was 9.4%(10/106). PCR detection of drug resistance gene positive strains 10 strains, consistent with the three-dimensional test results, EBC type Amp C enzyme resistant gene positive strains 6 strains, 3 strains of type DHA, type FOX 1 strains, no detection of MOX type and CIT type resistance gene.6. The positive rate of carbapenemase KPC type: 8 strains of carbapenem resistant enzyme drug strains in the modified Hodge test, the positive rate was 75%(6/8), the total positive rate was 5.7%(6/106), the detection of KPC carbapenemase resistance gene using PCR,positive strains were 4 strains were KPC-2 type resistance gene.7. Commonly used antimicrobial agents combined with the results of drug sensitive test in vitro: the ESBLs producing strains,(piperacillin / tazobactam) / Amikacin, Amikacin /(cefepime,piperacillin / tazobactam) / ciprofloxacin, meropenem / ciprofloxacin and meropenem / ratio of Amikacin FIC index of <1 were respectively 32.2%, 25% and 21.4%, 25.0%25.0%; on the production of Amp C enzyme strains,(piperacillin / tazobactam) /(ciprofloxacin,piperacillin / tazobactam),meropenem/ Amikacin / Amikacin / Amikacin, cefepime,ciprofloxacin meropenem/FIC<1 ratio was 40%, 30%, 30%, 20% and 20%, while thecephalosporin cefepime/although the ratio of ciprofloxacin of FIC<1 is 30%, but the ratio of FIC ≥2 to 60%; on 4 strains of carbapenemases, cefepime FIC <1, 2 strains(Amikacin, piperacillin/tazobactam)/ciprofloxacin, meropenem/ciprofloxacin and meropenem/Amikacin each of the 1 strains, of cefepime/Amikacin and(Cefoperazone / sulbactam) / Amikacin has 1 strains of FIC is ≥2.Conclusion Xianyang area of Serratia marcescens in sputum specimen source, the highest detection rate of severe medicine. The overall rate of good strains sensitive to antibiotics, resistance to one or two generation cephalosporins rate is high; the better sensitivity to the three or four generation cephalosporins drugs, can be used as a routine clinical medication; higher sensitivity to aminoglycosides, fluoroquinolones, carbapenems drugs, as the drug of choice in severe infection. It is also worth noting is that Serratia marcescens resistant to various antibiotics rate is rising year by year, and had the carbapenem resistant enzyme drug strains appear. Drug resistance in intensive care unit detected strain rate was significantly higher than that of the common ward, especially the aztreonam, cefepime, ceftazidime, Cefoperazone / Shubatan and ertapenem. On ESBLs, Amp C enzyme and carbapenemase producing strains have a certain percentage of emergence, enzyme production is the main mechanism of drug resistance of Serratia marcescens. ESBLs production of Serratia marcescens by CTX-M type and TEM type resistance gene, multidrug resistance gene of strains carrying a higher proportion of resistant gene; Amp C enzyme is mainly in EBC type, DHA type and FOX type are also detected; carbapenemase with KPC-2 type resistance gene based. The combined use of antibacterial drugs can enhance the effect of some certain serious infections caused by strains of ESBLs producing strains, caused by infection, can use/Amikacin(cefepime and piperacillin /tazobactam)/joint programme of the clayey ciprofloxacin; Sarre bacteria producing Amp C enzyme, can choose(piperacillin/tazobactam)/(Amikacin and piperacillin/tazobactam)/joint model of ciprofloxacin; cefepime/Amikacin and(piperacillin/tazobactam)/ciprofloxacin can be used for clay Sarre bacteria carbapenemases caused by infection, to provide basis for clinicians to select combined use of drugs. |
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