Global Foodborne Infections Network (GFN) National and Regional Projects
The Monophasic Goettingen project
We examined 22 monophasic Salmonella 9,12:l,v:- and 17 diphasic 9,12:l,v isolates from humans, animals and food products in Bulgaria, Denmark and the United States of America by serotyping and antimicrobial susceptibility testing. In addition, all strains were characterized by Pulsed Field Gel Electrophoresis (PFGE). All of the monophasic isolates were examined for presence of the fljB gene by PCR and 10 of them sequenced. Most of the monophasic isolates were almost fully susceptible to all antimicrobials tested whereas the diphasic Panama strains from Denmark were multiresistant. A total of four different PFGE patterns were observed among the monophasic Salmonella isolates when digested with XbaI. Pattern TEBX01.0001DK included isolates from both Bulgaria and Denmark whereas patterns TEBX01.0002DK and TEBX01.0004DK only were present in isolates from Denmark. Pattern TEBX01.0003DK was only observed in the strain from the United States of America. The patterns of the monophasic strains showed most relatedness to Salmonella Goettingen isolates compared to other diphasic 9,12:l,v isolates. All the monophasic isolates were positive for the fljB gene in PCR and sequencing of 10 strains revealed perfect match with the e,n,z15 group.
The study indicate that all of the Salmonella 9,12:l,v:- serovar investigated was of a monophasic variant of Salmonella Goettingen and are present in different countries and on different continents.
Reference: Eur J Clin Microbiol Infect Dis. 2009 May; 28 (5): 473-9. Eur J Clin Microbiol Infect Dis. 2009 May; 28 (5): 473-9.
The Nigeria project
The project focuses on the bacteriological and serological studies on Salmonella serovars in chicken meat in Nigeria. Two unique PFGE patterns were observed among the 35 S. Hiduddify isolates when digested with XbaI. The most common XbaI pattern included 33 isolates whereas the other XbaI pattern was given to only two of the isolates - #24 and #B4.
Analysis of the S. Hiduddify isolates using the composite data set of XbaI and the MIC results in combination revealed that the discrimination power was higher subdividing the S. Hiduddify isolates into eight types. Isolate #24 belonging to type VIII showed an unique MIC profile but shared the PFGE pattern with isolate #B4 belonging to type V. Isolate #24 have the same MIC profile (POD and CEP) as five other isolates. The data will be submitted in 2008.
Reference: Foodborne Pathog Dis. 2009 May; 6 (4): 425-30
The Salmonella Concord project
This study shows how international collaboration and sharing of information, even of potentially rare or isolated cases, can lead to the identification of a larger problem affecting the global community.
In addition, this is the first study to describe the spread of multidrug resistant Salmonella Concord in Europe and the United States of America among children adopted from Ethiopia. The outcome of this study suggests that multidrug resistant Salmonella Concord clones circulating among Ethiopian adoptee are distinct from other Salmonella Concord clones circulating in Africa. Based on the incident rate of infected Ethiopian adoptees from Denmark, we estimate that there could potentially be an estimated 52 000 orphans in Ethiopia infected with multidrug resistant Salmonella Concord.
The number of PFGE types observed suggests that Salmonella Concord may be a common and genetically diverse serovar in the region with an unknown reservoir(s). Further studies are needed to identify these reservoir(s). We feel it is essential to elucidate this problem so that intervention and prevention measures may be implemented for the benefit of the adoptees and the global community.
Reference: Pediatr Infect Dis J. 2009 Sep; 28 (9): 814-818.
Shigella in Thailand project
In Thailand during 1993–2006, a total of 9063 Shigella isolates from different medical centers were serotyped and trends over time and spatial clustering analyzed. Of 3583 cases with age information, 1315 (37%) cases were from children between 0 and 4 years and 684 (19%) from children between 5 and 8 years. Most infections were recorded during 1993–1994 (>1500 per year), decreasing to < 200 in 2006. The relative species distribution also changed. During 1993–1994, Shigella flexneri accounted for 2241 (65%) of 3474 isolations. This proportion decreased to 64 (36%) of 176 infections in 2006. Most infections occurred during July and August, and fewest in December. S. flexneri clustered around Bangkok, and Shigella sonnei in southern Thailand. Most S. flexneri infections were caused by serotype 2a (1590 of 4035) followed by serotype var X (1249). For both serotypes, a pronounced decrease in the number of isolates occurred over time. A much smaller decrease was observed for serotype 3a isolates. Phase I S. sonnei was initially most common, but shifted gradually over phase I, II, to only phase II. No differences in spatial distribution were found. The three most common S. flexneri serotypes all clustered in, around, and west of Bangkok. Serotypes 2a and 3a also clustered in southern Thailand, whereas var X clustered north and northeast of Bangkok. In conclusion, looking at Shigella species, Thailand changed from being a developing country to a developed country between 1995 and 1996. In addition, major shifts in the types of S. sonnei were observed as were differences in spatial clustering of S. flexneri and S. sonnei and S. flexneri serotypes.
Reference: Foodborne Pathogens and Disease Dec 2008, Vol. 5, No. 6: 773-784.
Salmonella in Henan province, China project
We characterized 208 human Salmonella isolates from 2006 to 2007 and 27 human Salmonella enterica serovar Typhimurium isolates from 1987 to 1993 from Henan Province, China, by serotyping, by antimicrobial susceptibility testing, and, for the most common serovars, by pulsed-field gel electrophoresis (PFGE). The most common serovars among the 2006–2007 isolates were S. enterica serovar Typhimurium (27%), S. enterica serovar Enteritidis (17%), S. enterica serovar Derby (10%), S. enterica serovar Indiana (6%) and S. enterica serovar Litchfield (6%). A high percentage of the isolates were multiple-drug resistant, and 54% were resistant to both nalidixic acid and ciprofloxacin. Of these, 42% were resistant to a high level of ciprofloxacin (MIC > 4 _g/ml), whereas for the remaining isolates, the MICs ranged from 0.125 to 2 _g/ml. Five isolates (2%) were ceftiofur resistant and harboured blaCTX-M14 or blaCTX-M15. With the possible exception of the quinolones and cephalosporins, the 1987–1993 S. enterica serovar Typhimurium isolates were almost as resistant as the recent isolates. PFGE typing of S. enterica serovar Typhimurium showed that the most common cluster predominated over time. Two other clusters have emerged, and another cluster has disappeared.
Reference: J. Clin. Microbiol., Feb 2009; 47: 401 - 409.