Stool Culture

Gastroenteritis and bacterial diarrhea are the most common forms of infections that occur both in children and adults. These infections are predominant in tropical regions. The most common etiology for diarrhea is either through parasitic infections or bacterial infections. Both these forms have distinctive clinical characteristics. The identification of the type of disease caused can provide a comprehensive route to differentiate and treat the disease through appropriate anti-parasitic or anti-microbial drugs.

Clinical symptoms

Gastroenteritis or enteric fever identification is characterized by abdominal discomfort, diarrhea and extreme dehydration. In most cases, these kinds of infections occur because of food or water borne contamination. The differential diagnosis of this condition in order to identify the disease is done through additional clinical symptoms, physiological changes and bio-chemical metabolic pathways. One of the most important factors in the identification of bacterial enteric fever is the presence of associated sepsis and spiking fever. In addition to this, in epidemic and highly infectious diseases like Cholera, caused by Vibrio cholera, the cyclic AMP(adenosine mono phosphate) levels are elevated leading to intense dehydration which can be fatal if left unattended.

Diagnosis

In case of bacterial enteric fever or associated diarrheas, stool specimens help understand and identify the type of organism causing the disease. Stool specimens are collected by patients in sterile container and the areas of stool in which blood and mucous are present are used for processing as they are useful portions of the specimen. The obtained media is usually transported by incorporating a transport media to avoid bacterial count decline because of varied PH of the external environment.

Microbiological media such as Selenite feces broth, Mackonkey agar, Salmonella Shigella agar, TCBS medium and Nagglers medium are used in the culture laboratory to identify disease causing organisms such as Salmonella(Typhoid, enteric fever) Shigella( Diarrhea) E.coli 0167or entero - hemorrhagic (Traveler's Diarrhea), Clostridium Botulinum(Food poisoning), Vibrio cholera( Cholera) and Campylobacter.

Apart from these bacteria, stool cultures are also done to identify the presence of enteric viruses such as Rota virus which causes viral gastroenteritis. All organisms isolated are subjected to respective antimicrobial assay to determine the suitable drugs for the respective organism. Careful precautions are taken and clinical details of the patient are recorded by the microbiologist to administer specific drugs for specific organisms. This helps to prescribe medications to specific persons too, such as pregnant and lactating women and children.

Herpes Blood Test

Blood tests to diagnose the presence of herpes virus antibodies can be done even if the patient does not have any visible symptoms. The standard available tests are not recommended since they are not very accurate. There is a potential for false positive results. A type specific virus culture will give an accurate result only when the sores have not healed. Herpes Simplex Virus (HSV-1) and HSV-2 are the most common viruses diagnosed using type-specific blood tests. There are three methods available to diagnose herpes - Cell Culture, Antigen test and Pap Smear test.

Herpes Western Blot Test: A more sensitive test than the viral culture is the Gold Standard test known as PCR DNA test. This test also known as Herpes Western Blot test, which is rated as an accurate test to identify DNA for viral particles which easily differentiates the two types, viz. type-1 and type-2. This test can be carried out safely during pregnancy. A wide range of antibodies that respond against many herpes simplex virus proteins are tested in Western Blot test.

BIO-KIT or POCKit TEST: Recently, a more accurate POCKit type-specific test has been approved by FDA (Food and Drug Administration) to diagnose herpes simplex virus-2. A doctor's office can do this Point Of Care (POCKit) test and provide results in just 10 minutes. This new test is cost-effective and less time consuming. A positive HSV-2 test result confirms genital infection. Sensitivity in this test is around 96% accurate. Using this test during pregnancy is not approved by FDA.

ELISA ,Immunoblot and IgG type specific Elisa are the other three tests carried out to diagnose HSV-1 & HSV-2 types with the sensitivity ranging from 96% - 100%. Blood drawn from the patient's arm is sent to local labs and the results are available in a fortnight.

Diarrhea

Diarrhea is a common illness caused worldwide. It is caused due to various reasons; infectious organisms such as bacteria, viruses and parasites of intestinal origin. The predominant clinical factor with respect to diarrhea is the onset of vomiting and fever causing extreme dehydration which is fatal and sometimes life threatening.

Bacterial diarrhea: In this case, bacteria such as Salmonella and Shigella and enterogenic E.coli cause damage to the intestinal wall causing more bowel movements and enteric fever. The diagnosis of bacterial diarrhea is done by stool culture and by serological analysis in case of Salmonella induced fever.

Viral Diarrhea: Viral diarrhea is most commonly noticed in children and it is usually self limiting after a period of four to five days. Symptoms include weakness, fever, irritability and sometimes vomiting.

Parasites: Intestinal parasites especially protozoan such as Giardia, Entamoeba and cryptosporidium cause diarrhea. Some are zoonotic on origin and mostly caused by feco-oral route.

Drug Induced: Diarrhea can also be caused because of the administration of certain type drugs such as antibiotics, anticancer and magnesium containing antacids.

Food allergies: Food induced diarrhea is common with those who eat at various places often. Some people are lactose intolerant and consumption of any diary product may induce diarrhea.

Treatment of Diarrhea

Diarrhea can be fatal if untreated. The most common form of treatment is through fluid replacement, rest and consumption of probiotics during the administration of antibiotics. Anti-parasitic drugs and antibiotics are most often prescribed. The WHO recommends ORS solutions in case children and adults as the preliminary step towards treatment and prevention of dehydration.