Study On The Antibacterial Activity Of Minocycline Combined With Cefoperazone/Sulbactam Against MDR-ABA In Vitro

PrefaceAcinetobacter baumannii (Acinetobacter baumanii, ABA) Pathogens as conditions in the hospital environment is widely distributed and can be long-term survival, which is a horrible threat to critically ill patients, and the CCU and ICU patients, Will this type of infection called ICU Acquired infections, the importance of the nosocomial infections caused by which exposured by more and more attention. In recent years, as a large number of multiple antibiotics are abused, Acinetobacter baumannii caused by the problem of antibiotic resistance of universal concern. Since 1991 erupted in New York for the first time of multidrug-resistant Acinetobacter baumannii (Multidrug-resistant Strains of Acinetobacter baumanii, MDR-ABA) after infection, the bacteria growing antibiotic resistance. Contrast 2004～2005 and 2007 China CHINET Acinetobacter baumannii resistance analysis results can be learned, Acinetobacter baumannii on imipenem and meropenem sensitive rate by 65.1% dropped to 60.6% and 56.8% dropped to 55.5%.In 2007 national 12 hospital drug susceptibility results of multiple drug-resistant Acinetobacter baumannii (MDR-ABA) has reached 47.7%(4.7%～64. 0%). Multi-drug resistant and even Pan-resistant Acinetobacter, to the hospital infection control and clinical treatment has brought about tremendous difficulties, called 21 century gram-negative bacteria in "Methicillin-resistant Staphylococcus aureus " (Methicillin-resistant Staphylococcus aureus, MRSA).Multi-drug resistant Acinetobacter baumannii (MDR-ABA) mechanism, disseminated, popular control as well as the antimicrobial is currently many researchers and clinicians focus.In recent years, through a lot of research for the treatment of multiple drug-resistant Acinetobacter baumannii effective medicines, including many colistin, Novel tetracycline, novobiocin and so on. Currently used in the treatment of imipenem of Acinetobacter infection optional drug coverage is very limited, and foreign tosylate (ampicillin/sulbactam), cefoperazone/sulbactam, colistin-E and colistin-B, novobiocin on imipenem Acinetobacter infection is valid, but the final choice should be based on clinical drug susceptibility test results.In 2005 with Prof. antimicrobial coverage of Acinetobacter baumannii on imipenem sensitive rate 70.7%, on meropenem sensitive rate was only 41.4%, cefoperazone/sulbactam and ampicillin/ sulbactam resistance rates to 25.1% and 35.5%. Another study showed resistance carbapenem of Acinetobacter baumannii (Carbapenem-resistant Acinetobacter baumannii,CR-ABA) tend to preparations containing sulbactam-sensitive, because it produces a variety of hydrolytic enzymes,which is the main mechanism.Unlike mostβ-lactam, sulbactam is different, which can directly act on bacteria of penicillin binding protein PBP-2, thus showing it on Acinetobacter unique bactericidal effect. Through CHINET 2007 surveillance of antimicrobial resistance among A. baumannii isolates in China to learn, the first affiliated hospital of Zhejiang University medical school, Peking Union Medical College Hospital and affiliated hospital of Guangzhou medical college isolation of strains of minocycline in lower rates of drug-resistant, even Peking Union Medical College Hospital and the First Affiliated Hospital of Guangzhou Medical College isolation of strains on minocycline drug resistance, respectively 14.0% and 24.1%, far below the carbapenem antibiotic resistance rates. So I wanted to observe for any collaborative or add role effective through studying to explore minocycline and cefoperazone/sulbactam on multi-drug resistant Acinetobacter baumannii, in order to provide experimental and theoretical basis for the treatment of clinical MDR-ABA infection laboratory.Materials and methodsStrains:Material collected in June 2008～March 2009, in the First Affiliated Hospital of China medical clinical isolates of various types of infection in 54 specimens of ABA, via VITEK-2 Analyzer identification, Adopts disk diffusion method (Kirby-Bauer method) For Manifested as multi-drug resistant strains.Standard quality control strains:Escherichia coli ATCC25922, Escherichia coli ATCC35218 (forβ--lactam/_-lactamase inhibitor combinations) from the hospital room freshman year to provide doctors. Antibiotics:(1) amikacin, cefepime, colistin, cefotaxime, ceftazidime, ceftriaxone, imipenem, levofloxacin, piperacillin, piperacillin/tazobactam, moxifloxacin, minocycline susceptibility of purchased from the Ministry of health of drug products. (2) minocycline standard products:the Ministry of health of drug products. (3) cefoperazone standard products:the Ministry of health of drug products. (4) sulbactam standard products:the Ministry of health of the drug products.Method:conventional cultivation methods, isolated bacteria, pure culture after VITEK-2 automatic Analyzer to identify Acinetobacter baumannii, using the disk diffusion method used for a variety of antibiotics, antimicrobial susceptibility testing will be more than 3 antibiotic resistance of strains identified as multi-drug resistant Acinetobacter baumannii (MDR-ABA). Method Miro broth dilution method. The effects of minocycline and cefoperazone/sulbactam (1:1) drug concentrations in turn times than dilution, set a dilution 11 concentration. The checkerboard method before the application for the determination of the subject of separate MIC value. Single-agent application on MDR-ABA MIC determination of the concentration as 3×105 CFU/ml of bacterio 100μl by adding holes, then add antibiotics 100μl, ultimately concentration through bacteria 1.5×105CFU/ml. Put 35±2℃incubator overnight culture, after 18～24 hours to observate the result, Record drugs alone the minimum inhibitory concentration, MIC with drugs alone and MIC b drug alone. Joint drug susceptibility testing according to the design Board:according to monotherapy MIC value, determine joint drug susceptibility testing of drug dilution. General selection 6 more dilution. Will 3×105 CFU/ml of broth 100μl by adding holes, then each antibiotic extraction 50μl by adding holes. Two combinations joined 96 plates. Put 35±2℃incubator overnight culture, after 18～24 hours to observate the result. Records two-drug combination the minimum inhibitory concentration, MIC a drug combination and MIC b drug combination. to calculate FIC index, which is the part of the inhibitory concentration index.ResultsMulti-drug resistant Acinetobacter baumannii rate for 66.7%(36/54),36 strains of Acinetobacter, minocycline, the sensitivity of the highest (80.5%), followed by more colistin (19.4%), imipenem (22.2%). On drug minocycline minimum (5.5%), followed by more colistin (66.7%), imipenem (77.8%). Of minocycline, colistin, piperacillin/ tazobactam intermediary with the highest rate (13.9%).Minocycline 30 strains of MDR-ABA MIC range as 1～8μg/ml, MIC 90 as 8μg/ml, cefoperazone/sulbactam on 30 strains of MDR-ABA MIC range as 16～128μg/ml, MIC90 as 64μg/ml. Minocycline and cefoperazone/sulbactam combination, minocycline MIC90 downgraded to 1μg/ml, cefoperazone/sulbactam MIC90 downgraded to 32μg/ml.DiscussionWith multiple drug-resistant Acinetobacter infections increasing its systemic infection caused by a single, generic drugs cannot get better results, preferred a combined application of antibiotics. At present, there are reports of minocycline on multi-drug resistant Acinetobacter baumannii resistance rate very low, and sulbactam pairs of unique bactericidal effect.After minocycline and cefoperazone/sulbactam Combined, the two antibacterial activity is significantly improved. In the treatment of multiple drug-resistant Acinetobacter baumannii caused severe infection, according to the clinical trials in vitro, prescriptions, minocycline and cefoperazone/sulbactam joint applications, rapid pathogen inactivation full, effective control of infection, reduce bacterial resistance at the same time, appropriate to reduce the application of minocycline, reduction of drug-induced adverse reactions to occur.ConclusionMinocycline and cefoperazone/sulbactam combined is a collaborative and add effects, they are not antagonistic. Clinical treatment by MDR-Ab caused severe infections, according to susceptibility test results with minocycline and cefoperazone/sulbactam joint application.