ABSTRACT
Objective To investigate the antibiotic susceptibilities and the profiles of virulence genes of clinically isolated Salmonella enterica serovars Schwarzengrund ( S. Schwarzengrund) strains for bet-ter understanding the epidemiological trend of this type of non-typhoidal Salomonella and to provide guide-lines for the prevention and treatment of S. Schwarzengrund infection. Methods Stool samples and clinical data of patients with acute diarrhea who received treatment in the Second Hospital of Tianjin Medical Univer-sity during May, 2014 to October, 2014 were collected for this study. Enrichment culture and biochemical identification were used to isolate and identify the S. Schwarzengrund strains. The isolated strains were fur-ther analyzed with serotyping analysis, drug susceptibility test, pulsed field gel electrophoresis ( PFGE) and multiple locus sequence typing ( MLST ) . The representative genes carried by Salmonella pathogenicity islands (SPI) 1-5, SPI regulators and virulence plasmids were amplified by PCR. The coding genes of CdtB-islet, which were cdtB, pltA and pltB were amplified and sequenced. Results In total, 16 (14. 8%) out of 108 non-typhoidal Salmonella strains were identified as S. Schwarzengrund strains and all of them were sus-ceptible to 11 kinds of antibiotics such as fluoroquinolone, ampicillin, ceftriaxone and trimethoprim-sulfame-thoxazole. PFGE categorized the 16 S. Schwarzengrund strains into 3 clusters including A clone ( 14 strains), B clone (1 strain) and C clone (1 strain). The strains that isolated from 8 patients who ate the same food belonged to one cluster ( A clone ) , suggesting that it was an outbreak of infection. The 16 S. Schwarzengrund strains showed identical MLST type, which was ST241. The representative genes carried by SPI1-5 ( invA, sitC, hilA, sseL, sifA, mgtC, siiE and sopB) , the regulatory gene ( phoP) and the cytole-thal distending toxin islet (CdtB-islet) coding genes (cdtB, pltA and pltB) were positive, while the genes carried by virulence plasmids (pefA, prot6E and spvB) were negative. The similarities in CdtB-islet coding genes and amino acids sequences between Salmonella typhi and S. Schwarzengrund strains in this study were more than 97% and 98%, respectively. Conclusion In this study, polyclonal S. Schwarzengrund strains of ST241 type were isolated from the patients. They were susceptible to common antibiotics, but carried the virulence genes contained in SPI1-5 and CdtB-islet coding genes and might cause an outbreak of infection. Attention should be paid to the tendency and threat of clinical S. Schwarzengrund infection and continuous surveillance and investigation should be performed.
ABSTRACT
Objective To investigate antimicrobial resistance and ceftriaxone resistance mechanisms in clinically isolated nontyphoidal Salmonella(NTS),and provide evidence for the prevention and control of NTS infection and rational use of antimicrobial agents.Methods 108 NTS isolates were isolated from stool specimens of outpatients with acute diarrhea in the Second Hospital of Tianjin Medical University and Tianjin Medical University General Hospital from May to October of 2014,NTS were performed antimicrobial susceptibility testing;non-ceftriaxone-susceptible isolates were typed by serological,multilocus sequence (MLST),and pulsed-field gel electrophoresis (PFGE)methods,extended-spectrumβ-lactamase (ESBL)detection and AmpC genes were detection.Results Among 108 NTS isolates,mono-drug resistance rate to 11 antimicrobial agents was 49.07% (n= 53),multidrug resistance rate was17.59% . Susceptibility rates to nalidixic acid,levofloxacin,ciprofloxacin,ceftriaxone,and ertapenem were 61.11% ,66.67% ,68.52% ,97.22% ,and 100.00% respectively. Three non-ceftriaxone-susceptible NTS isolates were detected,2 were ST11 Salmonellaenterica serotype (Sa8709,Sa8771),1 was ST34 Salmonellatyphimurium serotype(Sa8763). Cluster analysis of PFGE revealed that Sa8709 was highly similar to Sa8771 strains(91 .70% ), but the similarity to Sa8763 was low(55.80% );Sa8709 strain carried CTX-M gene,Sa8771 strain carried CTX-M and TEM genes,Sa8763 strain carried OXA gene. Conclusion Clinically isolated NTS in this area are low resistant to fluoroquinolones,multidrug resistant strains carrying ESBLs have emerged.
ABSTRACT
Objective To develop anoverlap syndrome (OS)rat model by intermittent hypoxia (IH) exposure on the base of pre-existing emphysema, and to explore its characters of severe systemic inflammation and immune responses. Methods Sixty Wistar rats were put into four groups:control group, IH group, emphysema group and overlap (emphysema+IH) group. The peripheral blood samples were collected for detecting apoptosis of CD3+CD4+,CD3+CD8+T lymphocytes and neutrophils (PMN). Tumor necrosis factor (TNF)-αand interleukin (IL)-6 were evaluated by ELISA. The bronchoalveolar la-vage fluid (BALF) was taken to calculate the ratio of macrophages, neutrophils and lymphocytes under light microscope. Tis-sue blocks of lung, liver, pancreas, and right carotid artery were taken for pathologic scoring. Results The apoptotic rates of PMN and CD3 +CD8 +T cells were significantly lower in overlap group than those of other three groups (P<0.05). Pro-in-flammatory factor IL-6, TNF-αand peripheral blood CD3 +CD4 +T cell apoptosis were the highest in overlap group com-pared to those of other three groups (P<0.05). The ratio of PMN and macrophages in BALF were significantly higher in em-physema group than those of other three groups (P<0.05) and the pathology scores of lung, liver, pancreas, the ratio of carot-id artery intima-media thickness of whole thickness of vascular were significantly higher in overlap group than those of other three groups (P < 0.05).Conclusion In rat model of intermittent hypoxia-emphysema there are more serious systemic multi-organ inflammation and immune responses.