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Clinical Microbiology

BACTEC culture system for the isolation of Mycobacterium tuberculosis and other species of mycobacteria:

1. Culture for Mycobacteria by BACTEC Micro MGIT method
2. Antibiotic (First line drugs - SHREZ) sensitivity for M. tuberculosis by BACTEC Method

BACTEC Micro MGIT READER
 
 
The clinically proven BACTEC SYSTEM provides the laboratory with faster test results in the isolation of mycobacteria.
With BACTEC SYSTEM results will be available in as early as 10 to 12 days from the time the patient specimen is brought to the laboratory or within 6 days from the time the mycobacterium is isolated.
The BACTEC system detects the presence of mycobacteria based on their metabolism rather than their visible growth.
A fluorescent compound is embedded in silicone on the bottom of 16 x 100 mm round-bottom tubes.
The fluorescent compound is sensitive to the presence of oxygen dissolved in the broth.
Initially, the large amount of dissolved oxygen quenches emissions from the compound and little fluorescence can be detected.
Later, actively respiring microorganisms consume the oxygen and allow the fluorescence to be observed using a 365 nm UV transilluminator or longwave UV light .
The BACTEC Micro MGIT system provides faster detection, objective results in the primary isolation of mycobacteria in a much desired standardized procedure.
First Line Drug Susceptibility Testing By BACTEC System against Mycobacterium tuberculosis
After the isolation of Mycobacterium tuberculosis from clinical specimen, antibiotic susceptibility testing to the following first line drugs will be performed (on request from the clinician) by BACTEC system.
Streptomycin, Isoniazid, Rifampicin, Ethambutol and Pyrazinamide
Drug susceptibility system for antibiotic testing of Rapid growers of Mycobacteria
After the isolation of Rapid growers of Mycobacteria (M. fortuitum /M. chelonae /M. abscessus) from clinical specimen, antibiotic susceptibility testing to the following first line drugs- amikacin, cefuroxime, ceftazidime, clarithromycin, tobramycin, ciprofloxacin, ofloxacin will be performed by disk diffusion method.
Gayathri R, Therese KL, Deepa P, Mangayarkarasi S, Madhavan HN, “Antibiotic Susceptibility Pattern of Rapid Growers of Mycobacteria (RGM)”. Journal of Post Graduate Medicine 2010; 56:76-8.
Therese KL, Gayathri R, Thiruppathi K, Madhavan HN. “First report on isolation of Mycobacterium monacense from sputum specimen in India”. Lung India. 2011; 28:124-126
Isolation of Herpes Simplex virus (HSV), Adeno virus and Chlamydia trachomatis:

CSF, Respiratory specimens:
To be collected in a sterile container and transported in ice to the laboratory with in one hour of collection

Swabs (pus, urethral swab, throat swab, swab from lesion or vesicle):
Collect the specimen using two sterile Cotton swabs and put in a screw cap vial containing viral transport medium (Minimum Essential Medium- MEM). The medium with the specimen should be transported in ice to the laboratory within one hour of collection

Direct Microscopy Of Bacteria, Fungus And Virus And Culture for Bacteria And Fungus
Urine for pyogenic bacteria:
Urine to be collected as per standard collection procedure and transported to the laboratory with in Half hour of collection
Urine for Mycobacteria (AFB) culture:
Early morning first voided urine sample to be collected in a sterile 500ml capacity bottle and transported in cold with in 2 hours of collection. It is recommended that the test be repeated on urine collected on three consecutive days.

CSF:
To collect in a sterile container and to be left at 37°C until transport. To be transported at room temperature to the laboratory with in 1-2 hours

Other Body fluids, respiratory specimens, biopsy, FNAB , pus etc:
To collect in a sterile container and to be kept at 4°C and transported to the laboratory in cold within 2 hours of collection for bacterial culture and within 24 hours of collection for Mycobacteria and fungal culture

Sputum for Mycobacteria (AFB ) culture:
Early morning first sample of sputum produced through a deep throated cough to be collected in a sterile wide mouth container and transported at room temperature within 2 hours to the laboratory. It is recommended that the test be repeated on sputum collected on three consecutive days.

Gastric lavage for Mycobacteria (AFB ) culture:
The specimen to be collected in a sterile container and transported within one hour to the laboratory at room temperature as the acid fast bacilli may be killed in the acidic nature of the specimen

Swabs ( pus, urethral swab, throat swab, swab from lesion or vesicle):
The material collected in two- three sterile swabs, put in a sterile test tube with a cotton plug, stored at 4°C and transported in cold within 2 hours of collection for bacterial culture and within 24 hours of collection for Mycobacteria and fungal culture

Skin scraping for fungus smear
The skin scraping can be collected from the periphery of the lesion with the blunt edge of a sterile blade, and the smear can be made on a new clean microscopic slide. The smear is fixed in methanol or with acetone, transported to the laboratory at room temperature with in 24 hours of collection preferably in slide mailer or wrapped in a clean tissue paper. The skin scraping can be collected from the periphery of the lesion with the blunt edge of a sterile blade, and placed in the envelope provided by the laboratory. The closed envelope can be transported to the laboratory at room temperature with in 24 hours

Slit skin preparation for AFB:
A superficial cut (taking care not to induce bleeding) is made at the site of lesion and a smear is made from the cut onto a new microscopic slide. The smear is fixed in methanol or with acetone, transported to the laboratory at room temperature with in 24 hours of collection preferably in slide mailer or wrapped in a clean tissue paper.