ABSTRACT
Objective To investigate the methods for identifying Actinomyces europaeus and to analyze its biological characteristics in order to provide a basis for the diagnosis of actinomycosis. Methods Pus speci-mens collected from patients were used for bacterial culture and then analyzed with Gram staining. VITEK 2 Compact automatic microbiological analyzer was used for species identification. Drug susceptibility test was per-formed with E-test. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry ( MALDI-TOF MS) was used to identify the isolated strain. The common primers of 16S rRNA were used for amplification fol-lowing DNA extraction, and the product of PCR was sequenced after recovery and purification. Homology analy-sis was conducted using the sequence in GenBank database. Results The drug susceptibility test showed that the strain was sensitive to penicillin, piperazolin/taclobatan, and ceftriaxone, but resistant to ciprofloxacin. MALDI-TOF MS and 16S rRNA gene assay identified the strain as Actinomyces europaeus. Conclusions MALDI-TOFMS and 16S rRNA could be used to identify Actinomyces europaeus and are of great significance for the diagnosis of actinomycosis.
ABSTRACT
Objective To construct cecropin A-thanatin combinant gene engineering antimicrobial peptide gene CA(1-7)-T(4-19) for expression in Pichia pastoris.Methods The combinant antimicrobial peptide gene was artificially synthesized via gene splicing by overlap extension (SOE).The gene was cloned into the pPICZαA vector and transformed into Pichia pastoris X-33 by electroporation.The positive clones obtained by the screening of bleomycin resistance were induced by methanol ,and the antibacterial activity of the products was detected and the antimicrobial spectrum was established.Results The combinant peptide gene CA (1-7)-T (4-19) was successfully cloned on the carrier pPICZαA.The identification results were consistent with the pre-designed gene sequence.The combinant peptide gene was expressed under the induction of methanol ,and the minimum inhibitory concentration of 76 strains of Gram-egative and Gram-positive pathogenic bacteria isolated from the clinic was obtained ,and the minimum inhibitory concentration was up to 5 μg/mL.Conclusion A combinant genetic engineering antimicrobial peptide with antibacterial activity was obtained successfully and it had obvious inhibition effect on clinical common multidrug-resistant strains.
ABSTRACT
Objective To identify a clinical isolate of Mycobacterium abscessus.Methods A pus sample was collected from a patient with suspected nontuberculous mycobacterial infection who visited the Affiliated Hospital of Weifang Medical University on December 18,2017,and was subjected to bacterial culture,Gram staining and acid-fast staining.Drug sensitivity test was conducted by the proportion method.The genome DNA of the strain was extracted and amplified by PCR with the universal primer of 16S rRNA.The PCR products were sequenced after collection and purification,and were compared with the known sequence of Mycobacterium abscessus in GenBank database.The isolate was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).Results The clinical isolate was identified as Mycobacterium abscessus both by MALDI-TOF MS and 16S rRNA gene sequencing.The drug sensitivity test showed that the strain was sensitive to amikacin,moxifloxacin,levofloxacin,but was resistant to streptomycin,isoniazid,rifampicin,ethambutol,ofloxacin,kanamycin,capreomycin,aminosalicylic acid,protionamide and rifabutin.The patient was diagnosed with subcutaneous soft tissue infection in the left knee joint.According to the results of drug sensitivity test,the patient was treated with amikacin and levofloxacin,and her condition was improved after treatment.Conclusion The 16S rRNA gene detection and MALDI-TOF MS both can be applied in the identification of Mycobacterium abscessus.