GFP-tagged E. coli shows bacterial distribution in mouse organs: pathogen tracking using fluorescence signal

PURPOSE: In vaccine efficacy evaluation, visualization of pathogens in whole organism at each time point would be able to reduce the consuming animals and provide the in vivo information within consistent background with identical organism. MATERIALS AND METHODS: Using IVIS spectrum whole live-animal imaging system, fluorescent intensity was optimized and visualized proportionately by concentrating Escherichia coli MC1061 strain which expresses GFP (E. coli-GFP) in BALB/C mice after injection. RESULTS: Local distribution of disseminated E. coli-GFP was traced in each organ by fluorescence. Detached organ showed more obvious fluorescent signal, and intestine showed strongest fluorescent signal. CONCLUSION: This in vivo imaging method using GFP-tagged pathogen strain suggest quantified infected pathogens by fluorescence intensity in whole animals can provide the information about the localization and distribution after infection.

The Laboratory Diagnosis of Melioidosis in a Korean Patient

Burkholderia pseudomallei is a gram-negative opportunistic intracellular pathogen that causes an acute and fatal septicemic melioidosis in humans. The organism is mainly found in Southeastern Asia and Northern Australia. Recently, we encountered a case of melioidosis in a Korean patient and performed the laboratory diagnosis of melioidosis. As a result, a gram negative bacterium was isolated from a melioidosis patient, and it was identified as B. pseudomallei on DNA sequencing of 16S ribosomal RNA with 99.9% homology and biochemical examination of VITEK gram-negative identification card. Also, DNA from cultured bacteria was tested in multiplex PCR, a 245 bp fragment amplified from the metalloprotease gene and a fragment of variable size ranging from 400~700 bp resulting from amplification of the 10 bp repetitive element for B. pseudomallei were confirmed after electrophoresis. The bacterium was sensitive to ceftazidime, imipenem and meropenem but resistant to ticarcillin. So far, there are no domestic cases of melioidosis in Korea, however, due to the increase in international travelers, the incidence of melioidosis is likely to increase. We report a recent case of melioidosis in a Korean patient.

Optimization of culture media of pathogenic Mycoplasma hyopneumoniae by a response surface methodology

Composition of culture medium for mass production of Mycoplasma hyopneumoniae was optimized using a response surface methodology (RSM). Initially, the influence of glucose, thallium acetate, fresh yeast extract, horse serum, and porcine serum on the production of mycoplasmal protein was assessed using a 'one factor at a time' technique. Next, factors with a significant effect, including fresh yeast extract, and horse and porcine sera, were selected for further optimization using a central composite design (CCD) of RSM. The experimental results were fitted into a second order polynomial model equation. Estimated optimal condition of the factors for maximum production of mycoplasmal protein (i.e., triple-fold increase from 0.8 mg/L produced by basal mycoplasma media to 2.5 mg/L) was 10.9% fresh yeast extract, 15% horse serum, and 31.5% porcine serum (v/v). For the optimized conditions, a 2.96 mg/L experimental result was observed, similar to the estimated optimal conditions result of the CCD.

Prevalence of Leptospira interrogans in Wild Rodents in Korea

Leptospirosis has been known as endemic disease in Korea since 1984. Wild rodent, mostly Apodemus agrarius, has been known as an important source of leptospiral infection especially in rainy circumstances in harvest reason of rural area. The infection rates of Leptospira interrogans in field rodents, Apodemus agrarius, was investigated by culture and PCR detection of leptospiral DNA, and compared with previous data. Furthermore, the serogroup and serovar were investigated. Two hundred twenty two Apodemus agrarius were captured during October to December 1996. Spirohaetes were isolated from 22 (9.9%) and leptospiral DNA was detected in an additional six rodents (12.6%). Subsequent cross-agglutinin absorption test, monoclonal antibody reactivity classified 21 cultures among 22 isolates as Leptospira interrogans serogroup Icterohemorrhagiae serovar lai. The above data did not differ from previous survey in 1984 to 1987. There was no significant change of Leptospira interrogans infection in field rodents in Korea.