Download Introduction to Microbiology

Transfusion-Transmitted
Infections
Introduction
• Blood transfusion is the process of
receiving blood or blood products into
circulation intravenously
Used in a variety of medical conditions to
replace lost components of the blood such
as:
• Inherited blood diseases: Thalassemia,
hemophilia, sickle cell anemia
• Hemolytic anemia of newborn.
• Bleeding: Post –traumatic, operative
• Malignancy: leukemia
• Other conditions: hepatic coma, kidney
failure
Procedure for Voluntary Blood Donation
Pre-Donation:
• Donor Screening
• Donor Consent Form
• Medical examination
Blood Donation:
o Blood donation procedure
Post donation
 Rest, advice & refreshment
 Donor Certificate, Donor ID card
Criteria for Blood Donation
(WHO Recommendations)
Donors are evaluated for safety
according to the following criteria:
• Age: 18-55 years old
• Weight: 50 Kg or above
• Pulse Rate: Normal 60–100 per
minute and a regular rhythm
• Body temperature: Normal 36- 37.6°C
• Blood pressure: Normal(systolic 120–
129 mmHg, diastolic 80–89 mmHg)
• Hemoglobin concentration: 12.5 g/dl
for females and 13.5 g/dl for males
• Medical History, epilepsy, psychotic
disorders, bleeding tendencies,
thalassemia, sickle cell anemia,
malignancy
• Infections: HIV, hepatitis, malaria,
syphilis
How much blood can be taken during blood
donation?
• The amount of blood drawn varies from 200
milliliters to 550 milliliters depending on
the country, but 450-500 milliliters is
typical
• The blood is usually stored in a flexible
plastic bag that also contains sodium citrate,
phosphate, dextrose, and sometimes adenine
Factors that play a role in establishment
of blood transfusion infection
• Viral Window Period: period between the
onset of infection and the appearance of
detectable antibodies to the virus (3-6
weeks up to 6 months)
• Donor immune status (Asymptomatic
immunocompetent donor)
• Laboratory and personal error
• Bacterial contamination
The Infectious Microbes
Transmitted by Blood
Transfusion
Transfusion Transmitted Infections
(TTI)
• HIV
• HTLV
• Hepatitis B and C
• Cytomegalovirus
• Epstein-Barr virus
• Human Parvovirus (B19)
• Human Herpesvirus 8
• Bacterial
contamination
of blood
products
• Syphilis
• Malaria
• prions
Human Immunodeficiency Virus
(HIV):
• Classification
• Family: retroviridae
• Genus: lentivirus
• Specie (types): HIV-1, HIV-2
• Lentiviruses are single-stranded,
positive-sense, enveloped
icosahedral RNA viruses.
Integrase
HIV Replication Cycle
 attachment (interaction b\w gp120 and
CD4) then interact with CCR5 and CXCR4
Entry and Uncoating
Formation of Ds DNA by reverse
transcriptase enzyme, and integration by
integrase.
Stay latent or reproduce (produce RNA and
proteins)
Assembly
release by budding destroying the cell
Routs of HIV Transmission
Unprotected sexual transmission
Blood transfusion
From mother to child (late in
pregnancy, during birth and breast
feeding)
Needle-sharing injection drug use
Percutaneous needle stick
Tissue transplantation
Human T cell Lymphotropic Viruses
(HTLV) type I and type II
Virology:
• Single stranded ss RNA
• enveloped
• Icosahedral
• Family: retroviridae
• Genus: deltaretrovirus
• Oncovirus
Pathogenesis
• The virus infect T cells and, activate
some host cell genes; and places the
infected cell in an uncontrolled mode
of growth
• The majority of infected patients stay
as carriers.
• Some patients develop Adult T-cell
leukemia (ATL) after 20-30 years.
Epidemiology
It is endemic in Japan (15-30%), Caribbean
(3-6%), Guinea and some parts of Africa
Transmission:
• Sexual route
• Blood transfusion
• Vertical transmission and breast-feeding
 Laboratory diagnosis:
• PCR for detection of provirus genome
• Anti-HTLV antibodies by ELISA
Hepatitis B Virus
Family: Hepadnaviridae
Icosahedral enveloped Ds DNA virus
One of the smallest enveloped animal
viruses.
Pleomorphic forms exist, including
spherical and filamentous bodies lacking
a core (none infectious lipids and proteins
surface antigen (HBs Ag))
incomplete forms
Transmission
• Highly infectious
• Sexual Route
• Vertical Route:
Transmission of virus from mother to child
during childbirth perinatal, transmission
of viral genetic material within the cells.
• Parenteral Route:
Blood transfusion and contaminated
syringes
Diagnosis
• Hepatitis B virus surface antigen (HBs
Ag) detection by ELISA for diagnosis
• Differentiation between acute and
chronic infection
Hepatitis C virus
• Virology: enveloped, Ss RNA virus
• Classification
• Family: flaviviridae, Genus: hepacivirus
• Transmission
• Blood\blood products transfusion
• Injection drug use
• Needle sticks or sharps exposure:1.8%
(range 0%-7%)
• Sexual exposure
• In developing countries, the primary sources of HCV
infection are inadequately screened blood and blood
products
Hepatitis C transmission in developed countries
Epstein - Barr virus: (EBV)
• Virology
• Family: Herpesviridae
• Enveloped, Icosahedral, Ds DNA
• Derives envelope from nuclear membrane
• Establishes Latency in B lymphocytes.
• Transmission
• Direct person-person contact (Saliva)
• Blood transfusion.
• Most adults are seropositive.
Pathogenesis
• EBV infects nasopharyngeal epithelial
cells, salivary and lymphoid tissues
• The virus binds to CD21 of BLymphocytes and acts as mitogen
(encourages a cell to commence cell
division)
• This will stimulate the production of
atypical reactive T cell (Downey
cells=70% of the total WBC count)
Downey cells
EBV Diseases and malignancies
• Diseases: asymptomatic in infants and young
children
• Heterophile positive mononucleosis (infectious
mononucleosis) (kissing disease) Fatigue, fever,
sore throat, lymphadenopathy, and
splenomegaly
• Lymphoproliferative disease: Uncontrolled BCell growth in immunocompromised patients
• hairy leukoplakia: nonmalignant, white-gray
lesions on the tongue in AIDS patients.
Hairy leukoplakia
• Malignancies
• Burkitt lymphoma
• Nasopharyngeal carcinoma
• Hodgkin lymphoma
• Diagnosis (serology)
• Anti-E.B virus IgM antibodies
detected by ELISA test
Lymphadenopathy
Cytomegalovirus (CMV)
• Virology
• Belongs to the Herpesviridae family like EBV
• Transmission: Saliva, sexual, blood transfusion,
vertical (during pregnancy, breast milk)
• Pathogenesis
• Latency in monocytes and macrophages
(mononuclear cells).
• Approximately 50% to 80% of the adult
population are infected with the virus
• Mononucleosis syndrome (like IM):
usually asymptomatic or mild symptoms.
• cytomegalic inclusion body disease ,
jaundice, hepatosplenomegaly,
pneumonitis, CNS damage (loss of
hearing & mental retardation), death.
(most sever in vertical transmission)
• Interstitial pneumonitis to severe
systemic infection (immunocompromised
patients : AIDS, tissue transplant)
Parvovirus B19
• Virology
• Ss DNA virus, non enveloped,
icosahedral virus
• Transmission
• Respiratory, vertical (from mother to
child), blood transfusion
• This virus has been transmitted to
patients with hemophilia through
infusion of clotting factors
• Pathogenesis
• It infects immature erythroid progenitor
cells, resulting in cell lysis
• The resulting anemia is clinically significant
in patients with sickle cell anemia
• Disease
• In children and adults
• Fifth disease; erythema infectiosum
(slapped cheek disease)
• In fetus
• Severe anemia, hydrops fetalis (anaemia &
edema)
Human Herpes Virus 8 (HHV-8)
• Virology: enveloped Ds DNA virus,
family: herpesviridae
• Transmission: Sexual contact, Saliva,
vertical, transplantation & transfusion
• Pathogenesis
• It has a gene that turns on vascular
endothelial growth factor (VEGF),
which plays a direct role in the
development of Kaposi Sarcoma
• Disease: Kaposi Sarcoma in
immunosuppressed esp. AIDS patients.
• Diagnosis
• Serology: ELISA
• Molecular genetics: PCR
Bacterial contamination
• The most common and severe infectious
complication associated with transfusion
• It has been estimated that 1 in 38,500
units of red cells, 1 in 3,300 units of
random donor platelets, are contaminated
with bacteria
• Gram–positive bacteria normally found
on the skin, such as S.epidermidis or
S.aureus, are the most common bacterial
contaminants of blood products.
• Gram negative bacteria, such as E.coli,
may contaminate the donation when
blood is collected from donors who
have bacterial infection without
symptoms.
• Improved methods of collection,
handling, and storing of blood
products has decreased bacterial
contamination in recent years.
Treponema pallidum
• Transmission: Sexually, transplacentanlly and
by blood transfusion (rare; 6 in million; can not
survive more than 48 hrs. in refrigerator)
• Bacteriology
• Thin spirochete; Basically it has Gram’s
negative cell wall
• Axial filaments present (endoflagella)
• Can not be cultivated in vitro; serodiagnosis
• Obligate pathogen (but not intracellular)
• Pathogenesis
Primary: genital chancre of skin
Secondary: skin lesions
Latent infection
Tertiary: CNS and cardiovascular
infection
Chancre
Diagnosis
• Direct:
Examination of microbe by Dark field or
immunofluorescent microscopes.
• Indirect (Serology)
• Non treponemal antibodies (non-specific
antibodies): Anti-cardiolipin by VDRL
or RPR test
• Treponemal antibodies (specific): by
TPHA or IFA
Malaria
• About 300-500 million people are infected,
over 1 million people die each year
• Transmission
• bite of infected female Anopheles
mosquito, transplacentanlly, and by blood
transfusion
• Microbiology
• Etiology: Plasmodium species (P.vivax ,
P.malariae , P.ovale , P. falciparum)
• Classification: Sporozoa
• Man is the intermediate host (asexual
stage of microbe= Schizogony cycle)
• Anopheles is the definitive host (sexual
stage = Sporogony cycle)
sexual cycle (Sporogony)
Asexual cycle (Schizogony)
Diagnosis:
• Thick and thin blood smears
• Rapid dip stick tests
Blood smear with Plasmodium falciparum
Map showing the distribution of malaria in the world:
♦ Elevated occurrence of chloroquine- or multi-resistant malaria
♦ Occurrence of chloroquine-resistant malaria
♦ No Plasmodium falciparum or chloroquine-resistance
♦ No malaria