Download Common bacterial infections

Common bacterial
diseases
L. Dalia Kamal Eldien
MSc in Microbiology
Lecture NO: 5
Outlines
 Pathogenicity of bacteria
 Example to Common bacterial diseases:
1. Urinary tract infection
2. Bacterial meningitis
3. Tuberculosis
4. Pneumonia
Pathogenicity of bacteria
 A pathogenic microorganism is defined as one that is
capable of causing disease.
 Although the mechanism of infectious process may vary
among bacteria, in general, be divided into several stages:
1. Entry into the host
2. Adherence to host cells
3. Invasiveness
 The pathogenesis of bacterial infection includes the initiation
of the infectious process and the mechanisms leading to the
development of signs and symptoms.
Common bacterial diseases
 Bacterial diseases include any type of illness caused by
bacteria.
 Examples to common bacterial diseases, include:o Urinary tract infection –UTIo Meningitis
o Tuberculosis
o Pneumonia
Urinary tract infection(UTI)
 Also known as acute cystitis or bladder infection, is
an infection that affects part of the urinary tract.
 Urinary system consist of kidney, ureters, urinary bladder&
urethra
 When it affects the lower urinary tract it is known as a
cystitis (bladder infection) and when it affects the upper
urinary tract it is known as pyelonephritis (kidney
infection).
Urinary system
Normal urine
 Normal urine color ranges from pale yellow to deep
amber — the cause of a pigment called urochrome and
how diluted or concentrated the urine is.
 Normal urine clear.
 Normal urine volume is 750 to 2000 ml/24hr
Cloudy vs clear urine
Sings& symptoms of UTI
 Symptoms of cystitis (bladder infection) include:
o
o
o
o
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Either frequent urination or urge to urinate (or both)
Dysuria (painful urination)
Cloudy urine with a strong odor
Blood in urine (hematuria)
Low-grade fever
Sings& symptoms of UTI
 Symptoms of pyelonephritis can vary depending on a
person’s age and may include the following:
o Fever
o Vomiting
o Flank pain (back, side, and groin pain)
o Chills
o Nausea
o Frequent, painful urination
Risk Factors of UTI
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Age& sex
Pregnant women
Renal Transplantation
Bladder Catheterization
UTI
 Urinary tract infections occur more commonly in women
than men, due the short female urethra.
 In men, the infection is low as a result of antibacterial
activity of prostatic secretions
• Explain why UTI common in female than male?
Common bacterial causing UTI
 Escherichia coli is the commonest urinary pathogen causing
60–90% of infections.
 UTIs caused by Pseudomonas, Proteus, Klebsiella species &
Staph aureus, are associated with hospital-acquired
infections, often following catheterization or gynaecological
surgery.
 Proteus infections are also associated with renal stones.
Diagnosis of UTI
 The diagnosis of UTI should be CLNICAL, based on
information& symptoms given by the patient to the
physician, and laboratory testing.
 A physical examination and lab tests complete the
evaluation.
Diagnosis of UTI
 Urine secreted in the kidney is sterile unless the kidney is
infected.
 Uncontaminated bladder urine is also normally sterile.
 The urethra, however, contains a normal microbiota, so that
normal voided urine contains small numbers of bacteria.
 Because it is necessary to distinguish contaminating organisms
from etiologically important organisms, only quantitative urine
examination can yield meaningful results
Diagnosis of UTI
 The most important lab test is urinalysis.
 A urine sample will be tested for signs of infection, such
as the presence of white blood cells and bacteria.
 Midstream urine also be "cultured." This means that a
small amount of the urine is cultured on a sterile media in
a petri dish plate.
 The plate is incubated for 24 hours , and then examined to
see what kind of bacteria are growing on it.
Plate culture for urine specimen
Antibiotics sensitivity test
 The isolated bacterial species' are treated with different
antibiotics to see which works best against them.
 This helps determine the best treatment for the specific
infection.
Antibiotics Sensitivity test
Bacterial meningitis
 The term meningitis inflammation of meninges (membrane
cover the brain and spinal cord) caused by:
a) Neisseria meningitidis: The pathogen is a small, non
motile, encapsulated, aerobic, Gram-negative diplococcus
b) Streptococcus pneumoniae Gram-positive, encapsulated
diplococci
c) Haemophilus influenzae type b. a small, non motile,
encapsulated, Gram-negative cocobacilli
Meninges
Bacterial meningitis
 All three bacterial species discussed above enter the body
by respiratory droplets from prolonged contact, such as
coughing, sneezing, or kissing.
 They then colonize the nasopharynx and sinus cavities
 However, should the organism invade into the nonciliated
epithelium and spread to the blood
 Once in the blood, all three pathogens are capable of
crossing the blood-brain barrier.
 The meninges then become inflamed, causing pressure on
the spinal cord and brain.
Sings& Symptoms
o
o
o
o
o
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Fever
Stiff neck
Headache
Nausea
Vomiting
Sensitivity to bright light
Diagnosis
 Clinically
 Imaging: X-rays and computerized tomography (CT) scans
of the head, chest or sinuses may reveal swelling or
inflammation.
 Laboratory: The definitive diagnosis of meningitis requires
an analysis of patient cerebrospinal fluid (CSF), which is
collected during a procedure known as lumbar puncture
(spinal tap)
Collection of CSF
Lumbar puncture syringe
Tuberculosis
 The major pathogens of tuberculosis are Mycobacterium
tuberculosis
 Mycobacteria are aerobic, acid-fast bacilli (rods)
 They are neither Gram-positive nor Gram-negative .
 They are virtually the only bacteria that are acid-fast. (One
exception is Nocardia asteroids)
 The term acid-fast refers to an organism’s ability to retain
the carbol fuchsin stain despite subsequent treatment with an
ethanol–hydrochloric acid mixture.
Tuberculosis
 M. tuberculosis is transmitted from person to person by
respiratory aerosol.
 Crowded conditions and poor ventilation contribute to
disease spread.
 In the body resides within reticuloendothelial cells
 TB is chronic disease takes much longer time to
symptoms appear
 Tuberculosis typically attacks the lungs, but can also
affect other parts of the body
Sings& symptoms
 A cough with thick, cloudy, and sometimes bloody mucus
sputum for more than 2 weeks.
 Loss of appetite
 Unexplained weight loss
 Night sweats
 Fever
 Fatigue
 TB of the kidney may cause blood in the urine
 TB of meninges may cause headache or Confusion
 TB of the spine may cause back pain
 TB of the larynx can cause hoarseness
Properties of M. tuberculosis
 Have high lipid content (60%) of their cell wall
 M. tuberculosis grows slowly, so must be incubated for 6
to 8 weeks before being recorded as negative.
 M. tuberculosis is relatively resistant to acids and alkalis
 M. tuberculosis is resistant to dehydration
Diagnosis
The diagnosis of tuberculosis include:
 Clinical diagnosis
 Radiological diagnosis by Chest Radiograph
 Laboratory diagnosis to isolate the causative bacteria by:
1. Direct miscopy staining techniques using Ziehl-Neelsen
2. Culture on Löwenstein-Jensen medium
Mycobacterium tuberculosis bacilli under
microscope by ZN stain
Löwenstein-Jensen medium
Pneumonia
 The term pneumonia refers to microbial disease of the
bronchial tubes and lungs.
 A wide spectrum of organisms, including viruses, fungi,
and bacterial species, may cause pneumonia.
 Usually acquired by aerosolized droplets
Symptoms of Pneumonia
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Cough (productive cough)
Fever, which may be mild or high
Chills
Shortness of breath, which may only occur when you
climb stairs
Healthy air way vs. one pneumonic one
Types of bacterial pneumonia
 " Basically, pneumonia can be classified in to :
A- Community acquired pneumonia is the most common
type of pneumonia because you can catch it in public
places such as a school or workplace
B- Hospital acquired pneumonia is more serious and
dangerous than community-acquired pneumonia as the
germs in hospital are more resistant to the drugs given
Diagnosis
 Physical Exam: The doctor will listen to the lungs with a
stethoscope. If their pneumonia, the lungs may make
crackling, bubbling, rumbling sounds& wheezing.
 Chest X Ray or Chest computed tomography (CT) scan
 Laboratory tests: sputum& blood specimen send to the lab
to diagnose the causative agent to culture.
Treatment
 Specific treatments depend on the type and severity of
pneumonia, age and the overall health. The options
include:
o Antibiotics: are used to treat bacterial pneumonia.
o Fever reducers such as Ibuprofen& Paracetamol
o Cough medicine: used to calm the cough so that to can
rest. Because coughing helps loosen and move fluid from
the lungs, it's a good idea not to eliminate the cough
completely.
By this lecture we finish the chapter of
bacteria
Sources for more reading
 Microbiology, Lippincott’s Illustrated Reviews. Cynthia Nau
Cornelissen, Bruce D. Fisher, Richard A. Harvey. Third
edition (chapter 3)
 Textbook of Diagnostic Microbiology-Fifth edition- Connie
R. Mahon, MS- Donald C. Lehman, EdD, MT(ASCP),
SM(NRM) - George Manuselis, MA, MT(ASCP)- Elsevier
(2015) (Part III –page 765, 854&884)
 District Laboratory Practice in Tropical Countries, Monica
Cheesbrough, Part 2, Second Edition