INTRODUCTION
Salmonella serotype spp. are enteropathogenic bacteria. Most people infected with Salmonella develop diarrhea, fever and abdominal cramps following 12 to 72 hours of infection. There are over 2000 serotypes of Salmonella currently circulating in nature. It is commonly found in humans, reptiles and birds. Salmonella can be found in birds, reptiles, insects, etc. Salmonella is a food-borne illness, found in foods such as eggs, meat and chicken. Salmonella can also be found on vegetables, on fruits and in water. Research has revealed that certain serotypes are more closely associated with particular foodstuffs. For example eating undercooked or raw-eggs are risk factors for acquiring S. enteritidis while eating meat is a risk factor for acquiring S. typhimurium DT 104. Anyone is at risk for acquiring Salmonella infections, given that there is a sufficient inoculum. Individuals that are more at risk for developing disease are people that are immunocompromised, usually people at extreme ages (the elderly and children).

Shigella is also a Gram-negative rod-shaped bacterium that is non-motile. A small inoculum is sufficient enough to cause diarrhea that results in bloody stools. Complications from Shigellosis include Reiter’s syndrome (combination of urethritis, arthritis, conjunctivitis) and hemolytic uremic syndrome. Humans serve as the only reservoir for the bacteria and transmission occurs via the faecal-oral route. Individuals that are at risk for developing shigellosis are children, individuals that live in unhygienic conditions (institutions), and men who have sex with men.

PURPOSE
Salmonella and Shigella are still problems to be reckoned with, especially with people are in some way immunocompromised. Reported rates of salmonellosis are higher among individuals with HIV than those without. Dysentery and chronic diarrhea from Shigella are more common HIV-infected individuals. Also, with the use of antibiotics in animal feed, you see more resistant isolates of Salmonella and Shigella; some that are resistant to multiple antibiotics, which makes it quite difficult to clear infections. A surveillance system must be put into place in order to monitor the serotypes and their antibiotic resistance patterns.

Caribbean Epidemiology Centre

The Caribbean Epidemiology Centre (CAREC) is administered by the Pan American Health Organization (PAHO) and the World Health Organization (WHO) on behalf of 21 member countries (CMCs) in the Caribbean. It serves as a public health institution that provides laboratory and epidemiological services to its CMCs. CAREC has been collecting information about Salmonella serotypes, Shigella serotypes and their susceptibility patterns. However, it has not been put into a manageable database. Creating and maintaining the database as well as performing some analysis should provide an accurate picture of what’s currently happening in the region. With a proper surveillance system put into place, public health interventions and better consulting can take place.

ACTIVITIES
CAREC’s 21 member countries have the facilities to test Salmonella and Shigella isolates, but the isolates are sent to CAREC for confirmation and serotyping. They are also tested for resistance to particular antibiotics. CAREC keeps records and laboratory books cataloguing every Salmonella and Shigella isolate that is sent to them for serotyping. A database was set up in EpiInfo 6.0. Fields created include CAREC number, Name, Specimen source, Serotype and Country of origin. Sex, age, date of isolate, date of onset wererecorded when the data was available. Antibiotic resistance results were recorded (when available) was recorded for the following antibiotics: Ampicillin, Chloramphenicol, Cephalothin, Cefitaxime, Gentamicin, Trimethroprim-sulfamethoxazole, Norfloxacin, and Ciproxfloxacin. I was able to enter in data for isolates received during the years 1996-2001. The analysis conducted includes the following:
• Prevalent serotypes that were circulating in the region
• Age and sex distribution of the people that had the infections to give some idea of who was suffering from the infections
• Antibiotic resistance patterns; isolates were tested against several antibiotics including Ampicillin, Chloramphenicol and Ciprofloxacin

RESULTS
For Salmonella and Shigella that 44.5% and 45.5%, respectively, of the infections are from individuals under the age of 1. This may be attributable to their immunocompromised state. For each year analyzed, the over 68% of the Salmonella and Shigella isolates come from two countries: Barbados and Trinidad & Tobago. For Salmonella, the majority of the serotypes received at CAREC are S. serotype enteritidis and S. serotype typhimurium. For Shigella in 1997, the prevalent serotype is S. flexneri type 2 but then in subsequent years, the majority of the isolates sent to CAREC are S. sonnei.

Overall resistance is pretty low in the Caribbean. In Salmonella isolates, the higher rates of resistance appear to reside with a combination of Ampicillin/Chloramphenicol(1.1%-16.6%), Ampicillin alone (0.8%-2.6%) and Gentamicin alone(1.5%-3.7%). There is no isolate with Ceftaxime resistance only and a multi-resistant strain of Ampicillin/Chloramphenicol/Trimethroprim-sulfamethoxazole/Gentamicin/Cefitaxime has shown up at CAREC twice, in both 1998 and 2001. With Shigella, there are higher rates of resistance with combination Ampicillin/Chloramphenicol (2.7-12.8%), and a combination of Ampicillin/Chloramphenicol/Sulfamethoxazole(6.8%-59.3%), and Sulfamethoxazole only(2.7%-9.2%).

The isolates that have been received at CAREC are not a representative sample of the serotypes that are circulating within the Caribbean. This is because the majority of the samples come from two countries: Barbados and Trinidad & Tobago. There are countries that have not sent isolates to be serotyped at all.

Report
Archive

Summer
2002

Summer 2001

Summer 2000

Summer 1999