Salmonella (cont.)
How are Salmonella infections diagnosed?
Feces of patients that have symptoms of food poisoning or typhoid fever are
cultured for Salmonella. Often, the diagnosis is first suggested by recognition
of an outbreak (multiple patients having symptoms of a disease all at about the
same time and often, from the same food or water source). Again, many organisms and toxins can cause food poisoning, so it is sometimes difficult to determine the outbreak's cause. Usually, the laboratory needs to be notified that
S. spp is suspected as the cause so they will choose the correct testing media (selective agar media) to distinguish Salmonella from other potential bacterial pathogens. The majority of Salmonella isolates come from the feces. Occasionally, Salmonella can be cultured from blood samples. Serovars are identified by serotyping (detecting bacterial proteins by using specific immunological tests).
How are Salmonella infections treated?
Treatment for enteritis or food poisoning is controversial. Some doctors
recommend no antibiotics since the disease is self-limited, while others suggest
using antibiotics such as ciprofloxacin for 10-14 days. Patients identified as immunosuppressed (for example, patients with AIDS or undergoing cancer
chemotherapy) should receive antibiotics. Some investigators believe antibiotics
prolong the carrier state.
Treatment for typhoid or enteric fevers with septicemia is not controversial.
Antibiotics, often given intravenously, are needed. These Salmonella species also should be tested for antibiotic drug resistance as some Salmonella species have been reported to be resistant to multiple antibiotics (also termed MDR Salmonella. Antibiotics usually chosen to treat Salmonella infections are fluoroquinolones and third-generation cephalosporins (used in children because fluoroquinolones are not indicated for use in children). Resistance to these drugs is a potential problem for those individuals that become infected with Salmonella as drug treatment options become limited.
Supportive therapy for both enteritis and enteric fevers consists mainly of
preventing dehydration and electrolyte abnormalities (for example, abnormal levels of
potassium and sodium ions) with fluids containing electrolytes (for example, IV fluids
or oral fluids like sports drinks).
Carriers of Salmonella are considered to be infected even though they may
show no symptoms. Carriers can infect other people and need to be cured of the
carrier state. About 85% of carriers can be cured by a combination of surgery to
remove their gallbladder and antibiotic treatments.
How can Salmonella infections be prevented?
Cleanliness is a key to prevention. Hand washing with soap and hot water,
especially after handling eggs, poultry, and raw meat is likely to reduce the
chance for infections. The use of antibacterial soaps has been recommended by
some investigators. By using chlorine-treated drinking water, washed produce, and
by not ingesting undercooked foods such as eggs, meat or other food, people can
also reduce the chance of exposure to Salmonella. Avoiding direct contact with
animal carriers of Salmonella (for example, turtles, snakes, pigs) also may
prevent the disease.
Public-health authorities that enforce restaurant cleanliness and employee hand
washing have helped in general prevention. Human carriers of Salmonella should
never work in the food-handling service industry and ideally should undergo
gallbladder removal and antibiotic therapy for an attempt for a cure of the
carrier state. Public-health authorities also ask for product recalls when
products are contaminated with Salmonella or other contaminating organisms or
toxins. In 2009, there was a recall for peanut-containing foods (for example,
peanut butter, cookies, crackers). The Westco Fruit and Nut Co., Inc., provided
peanut-based paste that was reported to contain Salmonella and was used to make
many food products. Eventually, about 3,800 products were recalled. Similar
recalls have occurred for pistachio nuts from a California provider in March of
2009 and for tomatoes in 2008, both contaminated with Salmonella. The most
recent recalls were for contaminated beef in July and August of 2009, and
unfortunately, the Salmonella showed multiple drug resistance. Recalls increase
the safety of the population from exposure to microbial and toxic food
contaminants.
Although some Salmonella vaccines are available for poultry and animals,
human vaccines are available only for typhoid fever. However, the CDC does not
recommend that everyone get vaccinated for typhoid fever; they recommend that
only those people going to developing countries where typhoid fever is endemic
(for example, regions in Africa, Asia, and Latin America) should receive the
vaccine. The typhoid fever vaccine is available in an oral (Ty21) and injectable
form (ViCPS). People planning to request these vaccines should notify their
doctors well in advance (about eight to 10 weeks) before they need the vaccine as it
may not be readily available and need to be administered about two weeks before
travel. Researchers are attempting to develop other vaccines for all types of
Salmonella infections.
Next: Where can I find more information about Salmonella? »
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