| Background & Objective:O. anthropi,which belong to Bacillus genus pale, is a type of non-fermented gram-negative aerobic bacteria, Before the 1980s,people thought it does not have clinical significance and non-pathogenic. But since 1980, Appelbaum et al reported the first case of pancreatic abscess caused by 0. anthropi, the cases about 0. anthropi had been reported more and more, and then gradually attracted people's attention. At present, most researchers believe that 0. anthropi is a kind of conditional pathogenic bacteria. The infection is often associated with local or systemic immune dysfunction patients, such as organ transplants, advanced cancer or immunosuppressive agents, overwork, etc, which can cause diseases such as sepsis meningitis, peritonitis. But in recent years, also there have been reports 0. anthropi can cause the onset of immune function normal population. So the bacteria has been thought of as a human pathogen. Through the Medline, Vaidya et al had searched 122 medical literature associated with pale bacillus of the genus in 41 people infected with 0. anthropi clinical case reports between 1989-2005, of which 15 were in immunocompetent patients infected with the bacteria literature.At present, about the clinical identification of bacteria, not many labs can start the 16 s gene sequencing technology in our country. The Vitek2 and API are the common tools. But both them, will mistake the pale of 0chrobactrum(such as intermediate Ochrobactrum?Pseudochrobactrum saccharolyticum), all of them will be identify as 0. anthropi; in addition, some other biochemical reactions Similarly bacteria will be mistaken as 0. anthropi (roses Aeromonas spp. Almost all the hospital for identifying genus for Ochrobactrum usually only the 0. anthropi. Therefore, there are some limitations of the routine method. Meanwhile, researchers about the Ochrobactrum anthropi resistance and resistance mechanism has been reported rarely at home and abroad. From the reported, we learnt almost most the 0. anthropi sensitive to imipenem, aminoglycosides, quinolones; but resistant for the cephalosporins, penicillin; and for nicefepime resistance rate is somewhat different. And resistance mechanisms of research is also very vague. Of the studies, the experimental Ochrobactrum strains were identified by Vitek2 or API. According to the Cai Tingting [3] preliminary studies,we found the resistance characteristics were different between the 0. anthropi?intermediate Ochrobactrum and Pseudochrobactrum saccharolyticum. In order to understand the 0. anthropi resistance situation,17 strains 0. anthropi which had identify by 16 s rRNA gene sequencing will be used to investigative the resistant phenotype, genotype and molecular epidemiology in my experiment,. (1) with Vitek2 Compact Gram-negative bacteria AST-GN13 identify susceptibility broth method and polymerase chain reaction (PCR) to detect 0. anthropi of common resistant phenotype and genotype, to found the multi-drug resistant circumstances and resistance mechanisms from different levels;(2) using PFGE to clear whether the strains infection by homologous? sporadic infection outbreak or epidemic infection, provide a theoretical basis for the hospitals prevention and control infection.Methods:During February 2012 to May 2013 a total of 17 strains not repeat 0.anthropi, which had been identify with 16 s rRNA gene sequencing by Li Gong-chang[10], Collected from Guangzhou, Beijing, Hunan and KingMed Diagnostics, The 11 common antimicrobial minimal inhibitory concentration of sensitivity test was performed by the microdilution method with Vitek 2 compact AST-GN13 card. Then PCR for detection of resistant genes intI1?int I2?int 13, GES?TEM?PER?CTX-M?VEB?SHV?CARB?ampC?ampR?DHA-1?aac(6')-??aac(6')-?? aac(3)-??aac(3)-??ant(2")-??ant(3")-??aph(3')-?? aph(3')-?? aph(3')-?? aadA2?qacE?1?mdfA?adeB?rmtA?rmtB?rmtC?rmtD armA npmA were performed. Pulsed-field gel electrophoresis (PFGE) of 17 0. anthropi isolates were performed to analysis molecular typing and strain homology.ResuIts1?The resistance rates of O. anthropi isolates to ATM?CAZ and TZP is 100%; the sensitivities of O. anthropi to FEP is 41.2%, showed partial resistance; the sensitivities to AMK (94.1%), GM (88.2%)?TOB (94.1%)?SXT (100%)? IMP (88.2%); And all strains of O. anthropi were sensitive to LVLX and CIP. The only one code-named 5652 resistant to AMK, gentamicin GM and tobramycin TOB.2?The intI1?intI3?ampC?ampR?aac(6')-?? ant(3")-??aadA2?qacE ?1 genes were detected in 5.9%,5.9%,100%,100%,5.9%,5.9%,5.9%, 5.9% by PCR; The intI2?GES?TEM?PER?CTX-M?VEB?SHV?CARB??DHA-1?aac(3)-?? aac(3)-??aac (6')-??ant(2")-?? aph(3')-??aph (3')-??mdfA?adeB?rmtA? rmtB?rmtC?rmtD?npmA genes were not detected. Except the ampC and ampR, the code for 5652 of O. anthropi also carry a variety of antibiotic resistance genes, including intI1?intI3?aac (6')-??ant (3")-??aadA2 and qacE?1.3?11 different PFGE types, designated from A to K, were distinguished among the 17 O. anthropi. Of these 17 isolates,4 clustered as the same type, designated type A.3 isolates designated type B,2 designated type C, one designated type D to K respectively. We found that the strains of each type were from different hospitals and different times, which means did not constitute an outbreak.Conclusions:Taken together, the 17 O. anthropi isolates have high rates of resistance from these areas, but also with the expression of resistance genes related. Produce cephalosporinase (AmpC enzyme)is the most important reason. Wherein the codenamed 5652 O. anthropi resistance gene was amplified a variety of resistance genes, including intI1?intI3, aac (6')-?, ant (3")-?, aadA2 and qacE?1. Consistent with the resistance results,we indicating that the mechanism of bacterial resistance increasingly complex. The PFGE results suggest that the outbreak did not occur in this area, But because the O. anthropi with multidrug-resistant, therefore need to actively cooperate with hospital infection management department to monitor drug resistance and prevent hospital infection outbreaks. |
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