clinical microbiology
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Clinical Microbiology. (MLCM- 201) Prof. Dr. Ebtisam. F. El Ghazzawi . Medical Research Institute (MRI) Alexandria University. Intended Learning Outcomes. By the end of this lecture the student should be able to - PowerPoint PPT PresentationTRANSCRIPT
Clinical Microbiology(MLCM- 201)
Prof. Dr. Ebtisam. F. El Ghazzawi.
Medical Research Institute (MRI)
Alexandria University
Intended Learning OutcomesIntended Learning OutcomesBy the end of this lecture the student should be able to
Understand all about Pathogens outside the enteric tract, Types, pathogens, and there Laboratory Diagnostic tests.
These organisms are usually opportunistic
pathogens that cause nosocomial infections,
especially pneumonia and urinary that
infections. Klebsiella pneumonia is an
important respiratory tract pathogen outside
hospital as well. Klebsiella species exhibit
mucoid growth, large polysaccharide
capsules and lack of motility.
Although Klebsiella is a primary pathogen,
patients with Klebseilla pneumonia infections
frequently have predisposing conditions
such as advanced age, chronic respiratory
disease, diabetes or alcoholism. The
organism is carried in the respiratory tract of
about 10% of healthy people, who are prone
to pneumonia if host defences are lowered.
Enterobacter and serratia infections are clearly
related to hospitalization, especially to invasive
procedures such as intravenous
catheterization, respiratory intubation and
urinary that manipulations.
Culture on Mac-Conkey’s agar red colonies
lactose-fermenting.
These organisms primarily cause urinary tract
infections both community and hospital acquired.
Proteus species move very actively by means of
peritrichous flagella resulting in swarming on solid
media unless the swarming is inhibited by
chemicals.
Proteus species Swarming motility on blood agar
Culture on blood agar will produce swarming.
Culture on Mac Conkey’s agar colourless
non-lactose fermenting colonies.
It is motile, rod shaped, gram-negative bacteria.
It is widely distributed in nature and is
commonly present in moist environment in
hospitals. It can colonize normal humans, in
whom it is a saprophyte. It causes disease in
humans with abnormal host defenses; patients
with extensive burns and in those with chronic
respiratory disease.
Ps. aeruginosa causes infections e.g. sepsis,
pneumonia, and urinary tract infections.
Severe external otitis and other skin lesions
occur in users of swimming pools and hot tubs
in which the chlorination is inadequate.
The organisms are strict aerobic and are oxidase
positive. They have a remarkable ability to
withstand disinfectants; this accounts in part for
their role in hospital-acquired infections.
Ps. aesuginasa produces two pigmens useful in
clinical and laboratory diagnosis:
1. Pyocyanin which can colour the pus in a
wound blue.
2. Pyoverdin (fluorescein), a yellow green pigment
that fluoresces under ultraviolet light, a
property that can be used in the early detection
of skin infection in burn patients. In the
laboratory, these pigments, diffuse into the
agar giving a blue green colour that is useful in
identification.
Pseudomonas aeruginosaBlue green pigment (pyocyanin) produced and diffuses into the agar
Specimen from skin lesions, pus, urine, blood,
spinal fluid, sputum and other material should
be obtained as indicated by the type of
infection.
Gram stain shows Gram-negative nods, that are
oxidase positive.
Culture on Mac-conkey’s or EMB agar show
colourless non-lactose-fermenting colonies. On
nutrient media or blood agar a blue green
colour pigment with fruity aroma is produced.
Bacteroides are the most common cause of
serious anaerobic infections, e.g. sepsis
peritonitis and abscesses. Bacteroides are
Gram-negative bacilli and may appear as
slender rods or coccobacilli. They are normal
inhabitants of the bowel. Normal stools
contain 1011 Bacteroides per gram.
By culturing anaerobically on blood agar
plates containing kanamycin or vancomycin
to inhibit unwanted organisms, where
characteristic coloured colonies are grown.
Assignment
Klebsiella.
Study QuestionsState the Laboratory Diagnosis for all kinds of pathogens outside the enteric tract.
Recommended TextbooksManual of Clinical Microbiology, Vols. 1 and 2: Eighth Edition Patrick R. Murray