Gram negative rods. There is one Salmonella species that is subdivided into S. typhii and S. paratyphi, the cause of typhoid fever, and all the other Salmonella of which there are over 2300 serotypes, causes of bacillary gastroenteritis aka the Hershey squirts.
Salmonella has 2 species, bongori and enterica; the latter species is divided into 6 subspecies: enterica (I), salamae (II), arizonae (IIIa), diarizonae (IIIb), houtenae (IV), and indica (VI). S. bongori and Salmonella subsp. II-IV have a marked increase in invasive disease compared with I (PubMed).
S. typhii is spread human to human, often from water sources or chronic carriers (especially in the gallbladder). The majority of S. typhii in the US is acquired from the Indian subcontinent (PubMed) and increasingly from Asia although about 25% of US cases are due to importation of contaminated food (PubMed).
Salmonella paratyphi A is associated with travel to South and Southeast Asia, and nalidixic acid–resistant infection is associated with travel to South Asia.
Salmonella paratyphi B infection is associated with travel to the Andean region of South America.
Salmonella paratyphi C infection is associated with travel to Africa (PubMed).
The other Salmonella are commonly found in eggs, chickens, turkeys, frogs, turtles (Pubmed), and reptiles of all kinds. It is rampant in the Congress. There have been outbreaks due to handling animal meat based pet treats (MMWR) and tomatoes (PubMed).
Salmonella enterica serotype Dublin is a cattle-adapted bacterium that causes bloodstream infections in humans. Get it from meat and milk.
S. enterica serotype Newport associated with beef and dairy cows (PubMed).
The easily pronounced Salmonella enterica Serotype 4,,12:i:- came from Europe, is found in US swine, and is multidrug resistant (PubMed).
Salmonella enterica serovar Napoli is common in Italy, initial outbreaks were from chocolate (PubMed). Oh, the pain.
Dog and human strains appear different, with dog strains have more antibiotic resistance (PubMed).
Also there was an outbreak associated with raw fish, but it was tuna, not salmon. When I was a kid I thought you got Salmonella from eating salmon. Everything, and I mean everything, has a fine layer of human or animal poo on it. Bon appetite.
And more from the CDC (PubMed): "Increased risk for enteric infection among workers in agriculture, health care, food, and personal care occupations might be related to workplace exposures to pathogens. Campylobacteriosis or salmonellosis should be considered when workers have symptoms compatible with these diseases." What? I should think of those organisms in patients with compatible symptoms? What a concept.
Acid suppression is a risk (PubMed).
Increasingly, outbreaks are associated with a variety of raw produce. It is why I only eat deep fried food.
And one outbreak with kids eating sand in the playground where wildlife were crapping in. Mmmmm. Sand containing crap. Playgrounds are a mixture of children and wildlife, a perfect mix for infectons.
S. typhii and S. paratyphi: typhoid fever, pulse temperature disassociation, leukopenia, abdominal pain, increased LFT's. A late complication of typhoid fever is perforation of the infected GI peyers patches.
In sub Saharan Africa, bacteremic non-typhoidal Salmonella is common in kids, especially S. typhimurium and S. enterititis which predominate and have a 25% case fatality rate.
Other Salmonella: gastroenteritis with and without fever and bacteremia in the elderly or the immunoincompetent (full text), osteomyelitis in sickle cell patients, infections of aneurisms (it has a propensity for the clot), chronic/relapsing bacteremia in HIV (rarely seen in the era of HAART, requires chronic suppression), acute cystitis, chronic cystitis in Schistosomiasis, a hodgepodge of extra-intestinal infections.
The Dublin strain has been increasing as a cause of invasive disease and is more likely to be resistant and kill than other Salmonella strains (PubMed).
Risk factors for vascular infection are male sex, hypertension, coronary arterial disease, and serogroup C1 infections, and the more you have, the greater the risk (PubMed).
Resistance is increasing to common antibiotics, so susceptibility testing is important. No antibiotic can be expected to be effective anymore (Pubmed). Quinolones (meta analysis suggests quinolones are the best therapy) and third generation cephalosporins are still reliable for most forms of Salmonella infections.
S. typhii in India has a 90% resistant rate to quinolones, but as amoxicillin, trimethoprim/sulfamethoxazole, and chloramphenicol resistance rates have fallen (PubMed). Gatifloxacin (10 mg/kg) qd for 7 days has same cure rates, but has fewer side effects, than chloramphenicol (75 mg/kg per day) qid x 14 days (PubMed). Not that either drug is in the US anymore.
Typhoid in Pakistan resistant to chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole, cephalosporins and quinolones (PubMed) aka XDR S. typhi (PubMed.)That would worry me more than the Taliban.
Resistance to Salmonella dates back to the 1950's and came from farm animals (PubMed).
Salmonella enterica serotype Dublin is often MDRO, including third generation cephalosporins.
In Asia quinolone resistance for enteric fever is common (PubMed).
In the West, Salmonella enterica strains have decreased susceptibility to ciprofloxacin; 103 (20.9%) of 492 isolates. The lower susceptibility was associated with ciprofloxacin treatment failures and with serovars and phage types acquired from foreign travel (PubMed).
As in most bacillary diarrhea, treatment for mild to moderate disease probably not indicated. If you decide to treat diarrhea, levofloxacin, 500 mg (or other quinolones) once a day for 7–10 days; or azithromycin, 500 mg once a day for 7 days; treat immunocompromised patients for 14 days (PubMed).
Cystitis, while rare, has a high relapse rate and perhaps should be treated for weeks (PubMed).
There is an association with diarrhea and subsequent bowel cancer (PubMed).
As an Oregonian, I note Salmonella was used in the 1984 Rajneeshee bioterror attack poisoning of 751 people (PubMed).
Relevant links to my Medscape blog
Last Update: 06/16/18.