Collection and Processing of Stool Sample

Collection and transportation of faeces

Faeces for the microbiological exam must be accumulated throughout the intense degree of diarrhoea.

I

In a hospital with a microbiology laboratory

1.Deliver the affected person a smooth, dry, disinfectant-loos bed pan or appropriate extensive-necked box In which to bypass a specimen. The container wants now not be sterile. Ask the patient to avoid contaminating the faeces with urine.

2.Transfer a component (approximately a spoonful) of the specimen, particularly that which incorporates mucus, pus, or blood, into a smooth, dry, leak-proof container. Worms and tapeworm segments: when the specimen carries worms or tapeworm segments, transfer those to a separate box and send them to the laboratory for identification.

3 .Write on the request form the colour of the specimen and whether it's miles shaped, semiformed, unformed, or fluid. record additionally if blood, mucus, worms, or tapeworm segments are present.

4.Label the specimen and ship it with a requested shape to attain the laboratory within 1 hour (if a postpone longer than 1 hour is predicted, acquire the specimen in Cary-Blair medium.

Important: whilst the specimen incorporates blood or amoebic dysentery is suspected, deliver it to the laboratory as soon as viable. A sparkling specimen is required to illustrate actively motile amoebae and also to isolate shigellae.

In a health centre for transport to a microbiology laboratory

1 .Request a specimen from the patient as defined formerly under the medical institution series of faeces.

Be aware: Leaves, cardboard bins, plastic baggage are no longer suitable for the collection of faeces.

2 .Switch a part of the faeces to a cotton wool swab. Insert the swab in a box of sterile Cary-Blair transport medium breaking off the swab stick to allow the bottle top to be replaced tightly. Salmonella serovars, Shigella, Vibrio and Yersini species continue to exist properly in Cary-Blair medium for up to 48 hours, and Campylobacter for up to six hours.

Note: Merthiolate iodine formaldehyde (MIF) solution need to no longer be used due to the fact MIF kills dwelling organisms. MIF is used as a fixative for protozoal parasites. Whilst cholera is suspected: switch about 1 ml of the specimen into 10 ml of sterile alkaline peptone water and label. The specimen should attain the Microbiology Laboratory inside eight hours of series.

3 .Write an outline of the specimen on the request form.

Note: while worms or tapeworm segments are present, transfer those (using forceps) to a container of physiological saline and send to the laboratory for identity. Commands concerning the packaging and dispatch of specimens may be observed .

Laboratory examination of faeces

The function of a microbiological laboratory in investigating infective diarrhoeal disorder With maximum sufferers, diarrhoea is self-proscribing and can be dealt with rehydration and other supportive remedies without the want for antimicrobials and microbiological investigations. The microbiological exam of faecal specimens is especially undertaken:

• To analyse outbreaks of dysentery (mainly shigellosis), cholera, and different acute bacterial infective diarrhoeal sickness of public health concern.

• To help the valuable public health laboratory in the surveillance of endemic shigellosis and salmonellosis (along with susceptibility of pathogens to antimicrobials).

• To diagnose symptomatic amoebic dysentery, giardiasis and other regionally critical intestinal parasitic infections.

Day 1

Describe the appearance of the specimen

• the coloration of the specimen.
• whether it's far fashioned, semiformed, unformed or fluid.
• Presence of blood, mucus or pus
• The presence of worms, e.g. Enterobius vermicularis, Ascaris lumbricoides, or tapeworm segments e.g. Taenia species.

Observe the specimen microscopically Saline and eosin arrangements to detect E. histolytica and other parasites

• Area a drop of fresh physiological saline on one ease of a slide and a drop of eosin stain on the alternative, using a chunk of stick or cord loop, blend a small quantity of clean specimen (particularly mucus and blood) with every drop. Cover each practise with a cowl glass.

Important: The eosin training must no longer be too thick otherwise it will no longer be possible to peer amoebae or cysts.

• Look at the arrangements the usage of the 10_ and 40_ objective with the condenser iris closed sufficiently to offer proper evaluation.

• Look specifically for motile E. histolytica trophozoites containing red cells, motile G. lamblia trophozoites, motile Strongyloides larvae, and the eggs and cysts of parasitic pathogens.

• Vicinity a drop of methylene blue stain on a slide. Blend a small quantity of specimen with the stain, and cowl with a cowl glass.

• Study the education for faecal leucocytes using the 40_ objective with the condenser iris closed sufficiently to give good contrast.
• The report also the presence of crimson blood cells (RBC) as those are often present with pus cells in inflammatory invasive diarrhoeal sickness .

Faecal leucocytes (WBCs): search for mononuclear cells and polymorphonuclear cells (pus cells). Mononuclear cells incorporate a nucleus which isn't lobed whereas polymorphonuclear cells comprise a nucleus which has or more lobes .On occasion, the cells are too broken to be identified (do not attempt to identify). Pus cells are related to the micro organism that motive irritation of the big gut regularly red cells also are discovered. Mononuclear cells are determined specifically in typhoid and in some parasitic infections, along with amoebic dysentery. reasons of inflammatory diarrhoeal ailment.

• Shigella species
• Campylobacter species
• Salmonella (non-typhoid serovars)
• histolytica
• EIEC much less not unusual:
• coli
• enterocolitica
• difficile
• perfringens (causing pigbel)
• Aeromonas species

Fundamental fuchsin smear to detect campylobacters put together whilst the specimen is unformed and, or, incorporates mucus, pus, or blood and is from a child underneath 2 y.

• Make a skinny smear of the specimen on a slide. While dry, lightly heat-restoration. Stain by way of masking the smear with 10 g/l primary fuchsin* for 10–20 seconds. Wash well with water and allow to airdry. *Dissolve 1 g basic fuchsin in one hundred ml of water, and filter out.

• Have a look at the smear for campylobacters the use of the 100_ oil immersion objective. Campylobacter organisms: search for plentiful small, delicate, spiral curved bacteria (frequently likened to gull wings), S-shapes, and short spirochaetal forms .

Note: Exam of stained faecal smears for campylobacters has been shown to be a sensitive method for the presumptive prognosis of campylobacter enteritis. Motility takes a look at and Gram stained smear when

cholera is suspected take a look at an alkaline peptone water tradition (pattern from the surface of the lifestyle) for vibrios displaying a rapid and darting motility. The practice is first-rate examined the usage of darkish-field microscopy but the

vibrios also can be visible the use of transmitted mild.

Possible pathogens

Gram-positive bacteria

• Clostridium perfringens
• Clostridium difficult
• Bacillus cereus (toxin)

Gram-negative

• Shigella species
• Salmonella serovars
• Campylobacter species
• Yersinia enterocolitica

References:

D greenwood, Slack RCB and J Peutherer.Medical microbiology.2001.

JG College, AG Fraser and BP Marmion.Practical Medical microbiology.Fourteenth Edition. Churchill Livingstone, 1996.

JP Micheal, ECS Chan and NR Krieg.Microbiology.Fifth Edition. Delhi: Mcgraw-hill, 1993.

M Cheesbrugh.Medical laboratory manual for tropical countries.London, 2007.