Clinical Application Of Carba NP Test To Detect CRE Strains And Analysis Of Factors Related To CRE Infection

Objective: To investigate the clinical application of Carba NP test which for detecting carbapenem-resistant enterobacteriaceae and analyze the antibiotic resistance, clinical epidemiology characteristics of these carbapenem-resistant enterobacteriaceae.Methods: Taking regular methods to identify the types of strains from clinical isolates and conducting K-B tests of antimicrobial susceptibility, to screen out the carbapenem-resistant enterobacteriaceae. E-test is used to detect the minimum inhibitory concentrations(MIC)of carbapenems. Modified Hodge test(MHT) and Carba NP I test are used to detect the carbapenemase, respectively. Then the Carba NP II test is used to classify carbapenemase which is positive in the Carba NP I test. E-test is used for the detection of metalloenzymes. Potymerase chain reaction(PCR) is used for the detection of resistance genes. Arranging and analyzing the clinical epidemiology characteristics of these carbapenem-resistant enterobacteriaceae.Results: 1. 51 strains of carbapenem-resistant enterobacteriaceae are chosen as the experimental strains. 41 of them are positive through Carba NP I test and these strains produced class B metalloenzymes confirmed by Carba NP II test. Using PCR method, we detect NDM-1 carbapenemase in all these strains. 2. The antibiotic sensitive rate of Amikacin, Levofloxacin, Chloramphenicol and Gentamicin to 51 strains of carbapenem-resistant enterobacteriaceae is <50%, while others are all resistance. 3. These CRE strains are mainly from the ICU(32/51) and mostly separated from sputum specimens(30/51). The top three CRE strains in the hospital are Enterobacter cloacae, Klebsiella pneumoniae and Escherichia coli, taking 78.43% of the total strains. The 28 strains of multidrug-resistant Acinetobacter Baumann(MDR-AB) are detected before or simultaneously when check out CRE. CRE strains are detected after 11-20 days in hospital and the percent of them is 41.18%. There are 49.2%(25/51) patients used carbapenem antibiotics before detected CRE. The 48 cases received one or more medical treatment of invasive operation. There are five cases died, three cases deteriorated and two cases transferred to another hospital from the 51 CRE infected patients.Conclusions: 1.NDM-1 is the main mechanism for carbapenem-resistant enterobacteriaceae in our hospital. 2. The Carba NP test has many advantages, such as convenience to use, highly consistency with PCR method and the result is easy to determine. 3. Long hospitalization period, living in ICU, accepting a variety medical treatment of invasive operation and using a variety of antibiotics treatment especially carbapenems are risk factors to infect CRE.