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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5512_Библиотеки_им_академика_М_И_Перельмана.pdf
Introduction to Diagnostic Micbiolo
J477
TABLE 19.1
Container or collection device Specimens
Swabs in sterile test tube
Sterile test tube
Sterile test tube with anticoagulant
Wide mouth jar or Universal cap (sterile) of 30 mL capacity Urine, sputum, faeces
Large wide-mouthed screw cap bottle (1 L)
Prescription bottle containing liquid or biphasic medium
and with screw cap
Containe and coection deces used for vaous specimens used in micbiological
investigation
Pus from infected wounds, throat and other sites
Biopsies (never place in formalin)
Body uids (ascitic, pleural joint)
-
Sputum for tuberculosis (Mycobacterium)
Blood culture
-
Note
Do not refrigerate the following specimens:
Transportation of Specimen
Drying
Bordetella pertussis,
Neisseria meningitidis).
Transport media
Charcoal-impregnated
swabs
Additional Information for Specimen Collection
basic rules
N. meningitidis pertussis
478
Mycobacterium
Neisseria
Haemo
Medical Laborato Technology: Volume 2
hilus
p
Laboratory Records
Book-in Ledger
Introduction to Diagnostic Micbiolo
J479
Technician's Record Book
Report Book
Procedures for Reporting of Results
Roue Laborato Reports
4so I
Medical Laborato Technology: Volume 2
B.
Introduction to Diagnostic Micbiolo
J481
Quantiation of Results
seriousness of the dis
ease.
grading in quantication
subjective.
population of the parasites
5
Safety Regulations
biological hazard
disseminating infection
workplace clean
clean the bench after work
rules of
personal hygiene.
wear a protective gown
or laboratory coat during work
formation
of an aerosol.
482
Medical Laborato Technology: Volume 2
frequent use of disinfectants.
10% formalin
immunization of laboratory personnel
Steps for Dealing with Mishaps Caused by Contaminated Materials
Skin cut or pricks:
Mouth contamination:
Eye contamination:
Cloth contamination:
Spilling on oor:
Breakage during centrgation:
Disposal of Specimens After Laboratory Use
discarded in antiseptic
Disinfection
Clostridium Mycobacterium
sewer
incinerated.
Introduction to Diagnostic Micbiolo J483
direct examination
Disinfection and Sterilization
Disinfection
Sterilization,
Disinfection
Phenolic solution
Procedure
Sterilization
removes all forms of life,
heat
ltration
(autoclave)
Incineration
Medical Laborato Technology: Volume 2
Use of a hot-air oven and an autoclave in the sterilization process is discussed in Chapter 4
of Vol. 1. The basic technique of ame sterilization will be discussed here because of its close
association with microbiology. Use of boiling water for sterilization will also be discussed as
materials required for this process are more readily available in laboratories of developing
countries.
Sterilization over a ame is used only for metals. It is ideal for sterilizing loops and needles
(Figure 19.11). Flame sterilization of loops and needles is separately discussed under
aseptic transfers. Flaming destroys any living forms on the surface of the needle or loop.
Bacteriological loops, vaccinating needles or lancets for taking capillary blood samples
should be heated in the ame of a gas burner or spirit lamp until they are red hot. Care must
be taken to avoid aerosol spray of the infected material during aming. Flame sterilization
of forceps, scalpels and such objects is quick, but is not suitable for general use. The hot-air
oven is more ecient to sterilize these objects. Never heat the scalpel too long on the ame.
Heat it for less than 2 min and it should not get red hot. Excess heat damages the sharpness
of the scalpel.
1. Dip the article in absolute alcohol or methanol.
2. Hold over the ame for a short period (less than 2 min). Never let a scalpel get red hot,
as it spoils the sharpness.
3. Pass the article up and down several times so that all parts get the heat.
Boiling
A temperature of 100
min. Most spores will be killed in 30 min at this temperature; however, some spores resist
for longer periods of time. The eciency of killing can be increased by adding 2% (w/v)
sodium carbonate, which increases the bactericidal eect of boiling water. The method is
not recommended if materials are to be stored in sterile condition for an extended period.
However, if the instrument (e.g., scalpel) is to be used immediately, the method is suitable,
and in addition, the salt prevents rusting. If other methods such as autoclaving and dry heat
are not available, sterilization by boiling should be considered.
Procedure (Figure 19.2)
1. Add demineralized water (or 2% w/v sodium carbonate solution) in the special boiling
pan or in a big saucepan, enough to allow space for boiling and to cover the equipment
to be sterilized.
2. Put in the glassware (e.g., syringes) when the water is cold but put the metal articles in
when the water is boiling.
3. Boil articles in the water for 30 min.
4. Leave articles in hot water until ready to use.
Autoclaving
Boiling water only reaches the temperature of 100
per square inch) can go up to 121
and dressings, nutrient media, contaminated specimens and others are subjected to steam
sterilization. Simple steam sterilization is achieved by the use of a pressure cooker whereas
large-scale sterilization requires autoclave. This is discussed in Chapter 4 of Vol. 1.
°
C (boiling water) kills all non-spore-forming organisms within 10
°
°
C Hence, the latter is more eective. Surgical equipment
C, while steam under
ressure (15 pounds
p
J485
FIGURE 19.2
MICROSCOPIC EINATION
a
The rst step in the laboratory diagnosis of pathogenic organisms is direct microscopic
examination of the specimen. Sometimes, if the organism cannot be cultured in the laboratory,
direct examination may be the only choice left for the laboratory. In the direct examination
of stained smears one should also look for the presence of cells other than the pathogen. For
example, in sputum or in urethral discharges, the relative number of neutrophils and
epithelial cells is almost as important for diagnosis as the presence and location of organisms.
Direct Examination (Wet Mount)
Direct microscopic examination of the specimen might help in the early identication of an
infectious agent and can guide in its laboratory culture. Although laboratory culture is pre
ferred for a conrmatory report, it takes a longer time (at least 18 h and sometimes 2-3 weeks)
than the direct examination. In case of emergency the physician may not have that much
time to wait; in such cases, the report of the direct examination is highly crucial. Sometimes
the organism caot be cultured and direct examination might prove to be the only way to
identify the infectious agent.
Direct microscopic examination may be performed with a wet unstained specimen or
with a dry-ed stained specimen. This reveals the morphological features as well as the
characteristic staining reactions of the microbe. The direct examination, however, should
be performed carelly in order to avoid misleading information due to the presence of
commensals and possible secondary invaders.
486 I
Medical Laborato Technology: Volume 2
Vibrio cholerae,
Dark-eld microscopy
neoformans
dry-xed stained smears
=
3
=
Haemophilus inuenzae Bacillus
anthracis
estimate the microbial population
5
preliminary report
(N. meningitidis),
(M. tuberculosis),
indirect microscopic examination.
Procedure for Wet Mount