Escherichia Coli (E. Coli) Infection – Transmission, Symptoms And Diagnosis
Escherichia coli (abbreviated E. coli) is a bacterium that lives in the intestinal tract of man and animals. All individuals have itÂ (starts to populate the intestinal lumenÂ 40 hours after birth) and is part of theÂ commensal flora (bacteria that live inÂ the body ofÂ a healthy personÂ but doesÂ not cause anyÂ disease). Newborn’s body comes in contact withÂ the bacteriaÂ through water, foods or hospital staff.
Although most strains of E. coli are not dangerous, there are exceptions, such as serotype O 157: H7, which is incriminated in the occurrence of serious food poisoning, anemia or kidney failure, or strains that may be etiologic agents of diarrhea and bleeding,Â enterohaemorrhagic E. coli (EHEC). Some strains of E. coli are incriminated in the occurrence of urinary tract infections.Â The bacteriaÂ is a comensalÂ while it does not posses virulence factors (genetic changes). It is believed that this bacterium is transmitted mainly fecal-oral due to poorÂ hygiene.
E. coli is a Gram-negative bacteria , that can not hold a special purple dye inside the cell. This test is very important,Â becauseÂ on this basis, bacteria are classified into two groups, depending on theÂ cell wall.Â E. coli can live inÂ Â aerobic environments (with oxigen)Â and anaerobic environments (without oxygen) therefore the bacillus is considered to beÂ facultative anaerobic. Some strains of E. coliÂ have increased mobilitity.
Contact with E. coli occurs early in lifeÂ of the individual, since the first days of life. E. coli can be contractedÂ from outside if you come in contact with biological products that contain faeces. For this reason, theÂ presence ofÂ E. coliÂ is an important factor inÂ determining theÂ fecal contamination of soil, water andÂ food.
Food Contamination With E. coli
Food can be contaminated with E. coli during cooking and can cause serious infections in humans if these products are not cooked properly. For example, if you do not cook theÂ meat to at least 70 degrees, bacteria will notÂ be destroyed, and theÂ risk of foodÂ poisoning exists. One of the most common forms of infection is consumption of insufficiently cooked meat. In addition, any food that comes in contact withÂ the contaminated meat will be contaminated as well.
FoodsÂ that may be contaminated with E. coli
Raw milk or dairy products – can spread bacteria from the cow’s udder in theÂ milk. To avoid consumption of potentially infected milk, pasteurizedÂ milk consumption is recommended.Â DuringÂ the process of pasteurization the product is brought to high temperatures that can destroy potentially pathogenic flora. Pasteurization does not destroy all microorganisms, but only those that can cause diseases.Â Fruits and raw vegetables which are not washed properly, and are eaten directly after being purchased, may be contaminated with bacteria. Some fruits and vegetables can also be pasteurized, and if possible, experts recommendÂ this option, includingÂ for natural juices. The list of foods that can be pasteurized include: nuts, honey, cheese, eggs, cream, soy sauce, wine, water, vinegar, juices, beer andÂ canned products.
Water contamination with E. coli
Sometimes, in conditions of non-compliance to hygiene measures animal fecesÂ get into contact with natural waters like:Â lakes, rivers, water reservoirs. Sometimes even water pools can be infected by ingestion or aspiration the body comes in contact with potentially pathogenic strains.Â Major E. coli outbreaksÂ are determined byÂ contamination ofÂ largerÂ water reservoirs, in the absence of effective systems of chlorination and disinfection
Direct transmission from person to person of E. coli
E. coli can spread from person to person, especially when basic standards of hygieneÂ are not met,Â when hands are not washed after goingÂ toÂ the toilet. E. coli can contaminate objects, and usuallyÂ people are not carefu,l and do not wash their hands and thus can get in contact with the skin of another host, thus indirectly transmitting infection.
E.Coli InfectionÂ Symptoms
Symptoms of E. coli infection vary significantly depending on the location of infection, host age and immune status at the time (which allows bacteria to multiply in the body). In some cases individuals are only carriers of pathogenic strains and did not developÂ infection – remain asymptomatic, but canÂ transmit E. Coli to otherÂ persons. ClinicalÂ stage begins 3-4 days after contractingÂ E.Â coli. Most patients develop aÂ gastrointestinal infection, because theÂ fecal-oral trasmission is the most common. In this case the infection is manifested by:
- Severe stomach pain, abdominal cramps and spontaneous tenderness to palpation of the abdomen ;
- Diarrhea, watery at first, but may become bloody (depending on the pathogenic strain);
- Nausea and vomiting
Children frequently develop infections with E. coli serotype O157: H7 (E. coliÂ enterohaemorrhagic) compared with adults. This strain is particularly dangerous because it has the ability to stimulate the formation of potentially lethal toxins. Serotype O157: H7 can cause life-threatening complications and can be fatal, especiallyÂ in small children and elderly persons. The most dangerous complications beeingÂ haemolytic uraemic syndrome and acute renal failure.
In some situations E. coli may end up contaminating the peritoneal cavity due to a perforated ulcer, perforated appendix, or even aÂ failed suregery leadingÂ to bacterial peritonitis, which can be fatalÂ without prompt treatment.
The clinical picture of patients with symptomatic infection with E. coli is not specific to this bacteria, there are many conditions that can cause the same spectrum of symptoms. Diagnosis of infection with E. coli can be relatively difficult to establish evenÂ to suspect, because bacterial infections that cause diarrhea are accompanied by high fever. In afebrile patientsÂ or very low fever,Â the doctor may overlook the possibility that the symptomsÂ could beÂ of infectious nature.
Symptoms induced by infection with common strains of E. coli occurred in a patient with competent immune system, which may limit the growth ofÂ E. Coli,Â will imporveÂ and even disappear in a week without complication. In such cases, patients recover without receiving special treatment, some evenÂ without seeingÂ the doctor for this problem. But if theÂ bacteriaÂ is more aggressive, complications can occur, mainly due toÂ fluid and electrolyte imbalances (presence ofÂ diarrhea) and acute renal failure. It begins at 2-14 days after infection. If complications arise, the patient’s general condition will worsen and the clinical picture may include:
- Cool, pale skin
- Temporo-spatial confusion
E.coli InfectionÂ Diagnosis
Investigation of patients who present to the infirmary complaining ofÂ explosive diarrheaÂ withÂ with onset ofÂ a fewÂ days and impaired general condition, is started with general history and physical examination.Â Patient history is the baseline of expert advice. YourÂ doctor will find more information about symptoms,Â risk factors, lifestyle, compliance with basic hygiene measures, personal history andÂ your close relatives (especially family members).
The main questions thatÂ theÂ physicianÂ may addressÂ the patient:
- When the diarrhea started, how long it took and how frequent is it?
- Is thereÂ blood, mucus or pus in the stool or is it just watery?
- Have you noticed chills or fever?
- Abdominal cramps, nausea, vomiting?
- Did theÂ general condition change? Did you encounter unusualÂ fatigue, irritability?
- Have you feltÂ dizzy?
The doctor may suspect an infection caused by E. coli if the following riskÂ factors exist:
- TheÂ patient came from aÂ care institution, elderly center, day care
- Consumption of inadequately cooked foods, restaurant meals (especially exotic restaurants)
- Semi-rawÂ meat consumption, unpasteurized milk, unpasteurized juices
- Contact with other patients who have recently had diarrhea
- Recent trips in areas with poor hygiene, non-potable water
- Recent administration of antibiotics.
History is followed by general physical examination during which the doctor will:
- Take the patient’s temperature
- Measure blood pressure and pulse
- Inspect skin, skin analysis by creating a consistent skin fold
- Abdomen palpation
- Perform a digital rectal examÂ to determine precisely whether or not traces of blood existÂ in the stool.
If an infectious diarrhea is suspected, samples of diarrheal stools, willÂ be analyzed microbiologically. Special stain are made,Â andÂ the sampleÂ will be placed inÂ differentÂ culture mediums toÂ determines the type of bacteria that isÂ responsible for the symptoms. Because it is possibleÂ that the bacteriaÂ to beÂ removed onlyÂ during the onset of symptoms, the best optionÂ is that the samplesÂ are collected quickly. For this reason it is recommended that patients present to the doctorÂ as soon as possible,Â especially if diarrhea contains traces of blood.
There are other more laborious andÂ expensive methodsÂ to diagnose anÂ infection with E. coli (immunoassay methods, immunofluorescent), but in general microbiological analysis provides the correct diagnosis. After the diagnosis of infection with E. coli has been established, some patients will be monitored more closely. These are groups at risk, very young or very elderly patients (extreme ages), those with compromised immune status, and all patients who are infected with highly virulent strains, known for their ability to cause complications. Monitoring involves periodic collection ofÂ urine samples, blood salmples and other testsÂ which show the overall health status.