| Objective:Central nervous system infection is mainly caused by bacteria, viruses and other pathogens which should not enter the cerebrospinal fluid (CSF) circulation. The infection is usually induced by a variety of factors such as brain surgery and diabetes. Domestic and foreign researchers have shown that gram-positive staphylococcus and gram-negative acinetobacter were the main bacteria which caused central nervous system infection. The diagnosis relies on clinical pathogen detection, but the traditional method for bacterial identification usually takes3-5days. Treatment of central nervous system infection is based on antibiotics but early clinical treatment is empirical medication because of the time requirement of traditional method of identification. Sensitive antibiotics will be used once etiological identification finishes. Studies have shown that increasingly severe antibiotic resistance occurred due to long-term use of antibiotics. In that case, infection could not be controlled well, which may make the condition much worse. Therefore, rapid and accurate pathogen identification is particularly important for treatment of the disease. In addition to traditional biochemical identification methods, mass spectrum as well as16S rRNA PCR is relatively rapid for bacteria identification. Studies have found that accurate rate of protein spectrum and PCR is higher than that of traditional biochemical identification.The aim of the present study was to further investigate the distribution and antibiotic resistance of pathogen which caused infection of central nervous system, as well as the differences of the various identification methods. From January2008to December2011, culture results of240CSF samples from Zaozhuang Municipal Hospital were retrospectively analyzed in this study. Identification by VITEK2was performed followed with mass spectrum and16S rRNA gene PCR of coagulase-negative staphylococci (CNS), respectively. Homology sequence analysis of staphylococcus was carried out and the phylogenetic tree of CNS was drawn. In order to further evaluate the situation of antibiotic resistance, drug sensitive test on staphylococcus epidermidis and G" bacteria was performed respectively, which could provide a basis for the clinical treatment of infection. In addition, we reported a rare case of acute motor axonal neuropathy (AMAN) caused by infection of Campylobacter jej’uni.Methods and Results:1. Identification of CSF strains by traditional biochemicalCSF samples were isolated and cultured followed with Gram stain. Through biochemical detection such as API and VITEK2, phenotypes of the strains were identified. The results showed that30.4%of the strains were identified as CNS (73/240),11.3%(27/240) as Acinetobacter baumannii,9.6%(23/240) as Gram-positive bacteria,8.3%(20/240cases) as Micrococcus,6.7%(16/240) as fungi,6.3%or less as other pathogens.2. Identification of CNS strains by mass spectrum (MS) and16S rRNA PCRMS was performed after identification by VITEK2. The results showed that also73out240strains were identified as CNS, and17.5%(42/240) were identified as Staphylococcus epidermidis,3.3%(8/240) as Staphylococcus hominis,2.5%(6/240) as Staphylococcus warneri,2.5%(6/240) as Staphylococcus haemolyticus,1.7%(4/240) as Staphylococcus capitis,0.8%(2/240) as Staphylococcus saprophyticus,0.8%(2/240) as Staphylococcus xylosus,0.8%(2/240) as Staphylococcus sciuri and0.4%(1/240) as Staphylococcus lugdunensis. Staphylococcus epidermidis accounted for one of the most common bacteria in infection of central nervous system. Results of16S rRNA PCR revealed that accuracy of MS was higher compared with VITEK2identification and the concordance rate of VITEK2was up to97.3%.3. Homology analysis of CNSPhylogenetic software was used for sequence alignment analysis of the CNS. The evolutionary tree showed that Staphylococcus haemolyticus, Staphylococcus lugdunensis, Staphylococcus hominis, Staphylococcus epidermidis and Staphylococcus xylose formed a branch with close relationship in the evolutionary tree, and Staphylococcus sciuri, Staphylococcus saprophyticus, Staphylococcus warneri and Staphylococcus capitis formed another branch with close relationship in the evolutionary tree.4. Analysis of antibiotic resistance of Staphylococcus epidermidisSusceptibility results showed that antibiotic resistance of Staphylococcus epidermidis varied among different antibiotics:penicillin (95.2%), erythromycin (80.9%), cefazolin (61.9%), cefuroxime (61.9%), cotrimoxazole (57.1%), clindamycin (54.8%), cefoxitin (52.4%), gentamicin (35.7%), ampicillin/sulbactam (33.3%) levofloxacin (28.6%), rifampicin (14.3%), fosfomycin (9.5%), while vancomycin and Linezolid presented a sensitivity of100%in Staphylococcus epidermidis.5. Analysis of antibiotic resistance in G" bacteriaAcinetobacter baumannii were identified in27out of the240CSF samples, among which antibiotic resistance was a common phenomenon. Resistance of Acinetobacter baumannii was as followes:cefotaxime (100%), cefuroxime (92.6%), ceftazidime (92.6%), ciprofloxacin (88.9%), piperacillin (85.2%), piperacillin/tazobactam (85.2%), amikacin (85.2%), cotrimoxazole (85.2%), cefepime (77.8%), the United States meropenem (74.1%), imipenem (70.4%), ampicillin/sulbactam (66.7%), cefoperazone/sulbactam (48.1%). Twelve samples were identified Pseudomonas aeruginosa and the resistance was as followes:cefotaxime (100%), cotrimoxazole (83.3%), ciprofloxacin (41.7%), piperacillin amoxicillin (41.7%), piperacillin/tazobactam (41.7%), levofloxacin (41.7%), amikacin (33.3%), ceftazidime (33.3%), cefepime (33.3%), cefoperazone/sulbactam (33.3%), imipenem (33.3%), meropenem (25%). 6. Case report of an acute motor axonal neuropathy (AMAN) case caused by Campylobacter jejuni infectionAMAN, a subtype of Guillain-Barre Snydrome (GBS) occurred in a patient with traumatic brain injury and diarrhea after single-injection of four hexose ganglioside sialic acid sodium. Laboratory examination showed high cerebrospinal fluid protein and normal cell count as protein-cell separation. Curved bacilli jejunum (CJ) culture showed positive result.Conclusion:The results above demonstrated that Staphylococcus epidermidis and Acinetobacter baumannii were two main bacteria which caused CSF infection in our hospital. Compared to VITEK2, MS showed higher accuracy in identification of pathogens which caused CSF infection. Antibiotic resistance was show in both Gram-positive cocci and Gram-negative bacteria in various degrees. In view of this, it should be more comprehensive in treatment of CSF infection. Cerebral trauma or CJ infection or monosialotetrahexosyl ganglioside sodium may be the cause of AMAN. |
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