Campylobacter pathogens
Campylobacter is a genus of bacteria consisting of mobile rods with a curved or spiral shape, not sporulated.
Microaerophilic, gram-negative, thermophilic and highly labile in the external environment, the bacteria belonging to the genus Campylobacter are among the microbial contaminants that are of major concern for human infections from contaminated food.
In particular, of the 15 Campylobacter species currently identified, only four are commonly associated with diseases in humans:
- Campylobacter jeujini, Campylobacter coli and Campylobacter lari : represent, in decreasing order, the species most commonly associated with human infection; they mainly cause intestinal infections that accompany the classic symptoms of gastroenteritis.
- Campylobacter fetus : responsible for extraintestinal infections in the newborn and in immunocompromised subjects.
Campylobacter infections are zoonoses (diseases transmitted by animals) spread all over the world, which do not spare even the most industrialized countries.
In industrialized countries, Campylobacter infections are much more common than one might think; in the USA, for example, campylobacteriosis affects no less than 2 million people each year, and is thought to outweigh Salmonella and Shigella infections together.
Contagion
The majority of Campylobatteri pathogenic infections result from the ingestion of beverages or foods contaminated with faecal material from infected animals. Even unpasteurized milk is an excellent vehicle, as is close contact with infected apartment animals. Among the foods most at risk we also mention not enough cooked chicken meat, and minced meat (like hamburger) in general.
Direct person-to-person transmission via fecal-oral route is also possible.
Compared to Salmonella spp. and Staphylococcus aureus, Campylobacter do not last long on surfaces such as Teflon and steel, due to their capacity to adhere to it. As a result, work surfaces and tools are not called into question as a source of food pollution. Moreover, given the poor resistance to adverse environmental conditions and to gastric acidity, the risk of food infection with pathogenic Campylobacter is mostly related to the consumption of raw or undercooked foods, which have undergone recent faecal pollution.
In temperate climates, Campylobacter infections are more frequent in the summer and autumn months, affecting children in greater proportion than adults and the elderly, who are better able to withstand the infection also thanks to the acquisition of a specific immunity following the previous infections.
Symptoms
The incubation period in humans lasts on average from 2 to 5 days, at the end of which affected patients complain of symptoms characterized by watery diarrhea, often hemorrhagic, with abdominal pain, fever, myalgia, headache, prostration and nausea, for this reason it is indistinguishable from that associated with diseases sustained by other enteric pathogens. These symptoms are caused by the powerful enterotoxins released by the bacterium, which are responsible for a food poisoning that strongly damages the cells of the intestinal mucosa and facilitates bacterial invasion. The intensity of the symptoms is however very variable, so much so that in those affected by mild forms the disease can run asymptomatically, while in more severe cases it can take on aspects similar to ulcerative colitis and Crohn's disease.
Complications
In most cases the infection remains confined to the intestine and represents a self-limiting pathology, although in the absence of treatment healing can take up to a couple of weeks. Only in pediatric or immunocompromised and strongly debilitated subjects, extra-intestinal infections can occur that involve other tracts of the digestive system (pancreatitis, cholecystitis), joints (reactive arthritis) or the nervous system (Guillan-Barrè syndrome) .
Treatment
Being an often self-limiting disease, the body tends to heal spontaneously in the space of a few days, without the need to administer antibiotics. These, in particular erythromycin (the antibiotic of first choice for Campylobacter enteritis), clarithromycin and azithromycin, can still be useful to accelerate healing and reduce the period in which the bacterium can be released with faeces. Unfortunately, over the years antibiotic-resistant Campylobacter strains have appeared, especially cephalosporins and penicillin, which complicate the therapy of infection in the most severe cases. The administration of liquids and electrolytes (rehydrating therapy) always represents the essential point of treatment; in the most severe forms it should be performed intravenously.
Prevention
As anticipated, the pathogenic Campylobacter are not very resistant in the external environment; for example, they rapidly become inactivated when exposed to oxygen and low environmental humidity. Even the acidity of the stomach is an excellent defense against infection, although not always sufficient to prevent infection; in this regard, we recall that individuals treated with antisecretory drugs, such as proton pump inhibitors and H2 antagonists, are more exposed to the risk of contracting Campylobacter infections.
Given the scarce resistance of the bacterium to adverse environmental conditions, the cases of epidemic food campylobacteriosis are rare. Prevention is based on cooking food, drinking exclusively drinking water (in sealed bottles when going to developing countries) and carefully cleaning hands (washing with hot water and soap) after being in contact with animals, even domestic animals, before food preparation and between the handling of raw food and food already prepared ..
