Infectious Diseases Flashcards
conditions or diseases associated with
pathogens.
Infectious Diseases
microorganisms or microbes which
has the capability to cause diseases.
Pathogens
Most commonly encountered pathogens are
bacteria, fungi, virus, & parasites
HOW TO IDENTIFY THAT A DISEASE/CONDITION IS
CAUSED BY AN INFECTIOUS AGENT?
- diagnosis itself is done by the physician.
- MedTech isolates the pathogens from different clinical
specimens.
- Classical or traditional way of identifying organisms.
- Phenotype focuses more on the physiologic properties of
microorganisms.
o Dealing with something we can observe either
through the naked eye or with microscope
PHENOTYPING ANALYSIS
Most common example of microscopic assays for identifying
is through the ____
o To determine the absence or presence of a
microorganism on the sample
o _____ has no name yet.
Staining Procedure
One of the most important artificial environments is
the______
culture medium
Nucleic Acid Amplification Techniques
- The molecular detection of pathogens directly in clinical specimens such as blood, tissue, bronchoalveolar lavage
fluid, and other body fluids most often is accomplished
through PCR-BASE AMPLIFICATION
DIAGNOSIS USING NAATS
- This technique can overcome low sensitivity to improve the
specificity of conventional phenotypic tests.
Nucleic Acid Amplification Techniques
Common target for the following microorganisms:
▪ Bacteria – 16S rRNA or 23S rRNA
▪ Fungi – 18S rRNA
- The most common sequencing assay is Next Generation
Sequencing (NGS) technique. - Under the sequencing assay, the most common target is
the 16S rRNA.
DIAGNOSIS WITH SEQUENCING
- _____ are fastidious, facultative, intracellular zoonotic, and arthropod vector-borne bacteria distributed among mammalian reservoirs worldwide
- unique feature of these species is that they are under
the group of Spirochetes
BARTONELLAE SPECIES
Because of their hemotropic lifestyle, Bartonellae typically are transmitted by
arthropods within mammalian reservoir
communities
blood-sucking
- fever,
- malaise,
- headache,
- rash,
- lymphadenopathy,
- psychiatric disorder,
- bone and joint pain,
- anemia,
- various inflammatory
- vascular proliferative disorders.
symptoms associated with Bartonella infections
- One of the mostcommon arthropod associated with Borrelia species are TICKS
- Infected with this genus is associated with a unique sign which is a characteristic bull’s eye like rash.
TICKS
Using the traditional microbiology method for diagnosing
bacterial isolate, this species may actually be seen by ____
performing blood smear preparation
- These bacteria are a known cause of sexually transmitted
diseases (STDs) in the United States. - They are clinically important because majority of the
infected individuals are presented as having asymptomatic
(mild) signs and symptoms.
CHLAMYDIA TRACHOMATIS
one of the best and common targets
for amplification technique because it contains introns which can be amplified via a multicopy
CRYPTIC PLASMID
- For detecting the transmission pattern or the pattern of
spread - For forensic purposes for cases associated with sexual
assault - Typing is based mainly on discrimination of the 15 different
serovars encoded by the ompA (omp1) gene
o Different strains can be detected using the
particular technique
REASONS AND APPLICATIONS OF TYPING CHLAMYDIA
TRACHOMATIS
- Another organism that is difficult to grow using the classical method because they are considered as anaerobic organism.
CLOSTRIDIUM DIFFICILEA
an anaerobic, Gram-positive, spore-forming bacillus that can be found in the environment and the gastrointestinal tract of animals and humans
C. difficile
The main reason why this is the most commonly used assay is because the bacteria become pathogenic when it
releases a toxin
TISSUE CULTURE CYTOTOXIN ASSAY
- It is a one-step, rapid, and specific screening method for C.
difficile toxin genes.
MULTIPLEX PCR
- common cause of upper and lower respiratory tract infections in children and adults
- recognized as one of the most common pathogens causing
community-acquired pneumonia in
certain populations, especially in children among whom infection can lead to severe pneumonia requiring
hospitalization. - It does not retain any dye (stain). Thus, their presence cannot be observed because it is the only bacteria that does
not contain a cell wall
MYCOPLASMA PNEUMONIAE
To detect this species, the most widely applied NAAT for
detection is ____
PCR
o 16S rRNA
o P1 – most commonly used and best targets for
identification. It contains the signature sequence of
the species.
o Tuf
o parE
o dnak
o pdhA
o ATPase operon
o CARDS toxin gene (mpn372)
o repMp1
different gene targets
- includes Gram-negative, small, obligate intracellular, nonmotile, pleomorphic coccobacilli bacteria transmitted by
arthropods. - main clinical manifestations of a ____ syndrome in humans are fever, rash, and eschar with different
combinations, but they are not pathognomonic.
RICKETTA SPECIES
THREE SIGNS AND SYMPTOMS
- Fever
- Rash
- Eschar (blackening of the infected area)
based mainly on recognition of
sequences from different targets:
o 16S rRNA gene
o Protein-coding genes (i.e., outer membrane
protein)
Molecular detection
considered as the best specimen to use
skin or eschar biopsy and
autopsy organ tissue
In specific situations in which there are no other options, _______ also can be performed from plasma, serum, paraffin-embedded tissues, or even fixed-slide specimens.
molecular detection
It is one of the most common isolates in the laboratory.
- . In a classical method of culturing microorganisms, S. aureus are
most isolated because it causes a wide variation of
diseases.
STAPHYLOCOCCUS AUREUS
MOLECULAR TECHNIQUES USED FOR DETECTION
- PCR
- REAL-TIME-PCR
- WHOLE GENOME SEQUENCING
best molecular diagnostic tool for MRSA detection
PCR
latest development in the direct MRSA
detection and identification
Real-time PCR
method that could be used to predict resistance, assess virulence, and type
isolates at the highest possible resolution.
Whole Genome Sequencing
- Also, a causative agent of pneumonia.
- Primers used in PCR testing are specific to repetitive
regions and genes encoding:
o rRNA
o Pneumococcal surface adhesion A molecule
(psaA)
o Pneumolysin (ply)
o Penicillin binding protein
o Autolysin (lytA) – best and most commonly used
STREPTOCOCCUS PNEUMONIAE
- It is a counterpart of S. aureus because it also causes a
wide variety of infections and conditions. - It is also termed as Group A Streptococcus (GAS).
STREPTOCOCCUS PYOGENES
identifies specific rRNA sequences of
Streptococcus pyogenes in pharyngeal specimens by a single-stranded chemiluminescent nucleic acid probe
GASDirect test
o It is applied for primary testing
o It is used as a backup test to negative antigen tests
o Batch screening of throat cultures
MAIN ADVANTAGES OF THE ASSAY
- the leading cause of neonatal
sepsis and meningitis and is responsible for high mortality
and morbidity, particularly in invasive infections of neonates. - It is also an important pathogen in elderly patients and those with underlying diseases that impair immunological defense mechanisms against pathogenic microbes.
- It is also known as Group B Streptococcus (GBS).
STREPTOCOCCUS AGALTIAE
- Instead of the newborn, the mother is screened for the
detection of the colonization of GBS.
o The mother is screened because some female
individuals contain colonization of GBS in their
vaginal area.
o A vaginal swab or rectal swab are performed.
CULTURE METHOD
- Performed for the rapid detection of GBS
- Main target genes include:
o sip
o cfb – responsible for the release of CAMP factor
and the most commonly used for detection
o scpB
o ptsI
CONVENTIONAL AND REAL-TIME PCR ASSAYS
- It uses probes that targets the cfb gene.
- When using this technique, 4 to 6 primers are used and
detection of the species is within 90 minutes
LAMP METHOD
- through PCR Probes and PCR Formats.
- directly in clinical specimens most often is accomplished through PCR-based DNA amplification or isothermal amplification
- The main targets include: rDNA, cytochrome b, β-tubulin,
calmodulin, enolase, chitin synthase, and heat-shock
protein. - Aside from amplification techniques, sequencing techniques
can also be used.
MOLECULAR DETECTION OF FUNGI
- Aspergillosis, defined as an infection caused by organisms
included in the genus Aspergillus, constitutes a spectrum of
diseases that range from allergic reactions to disseminated
disease in immunocompromised hosts - Majority focuses on this species among clinically significant
fungi
ASPERGILLUS
rapid and accurate diagnosis
Nucleic Acid Amplification Tests (NAATs)
targeting fungal rDNA have been used for the detection of Aspergillus in fresh and FFPE tissues without requiring nucleic acid extraction or
amplification
In situ hybridization (ISH) probes
- classified as a member of the family Retroviridae and genus Lentivirus based on the biological, morphological,
and genetic properties.
-
HUMAN IMMUNODEFCIENCY VIRUS
the most virulent and pathogenic, and
when people talk about HIV without stating the
type of virus they usually are referring to HIV-1.
This occurs globally
HIV-1
constrained only to some areas of Central and Western Africa.
HIV-2
Codes for CORE
STRUCTURAL
CHON
Main focus of
molecular
detection – P24
gag
- Transcribes RNA
into DNA - Degrades RNA
- Makes HIV
particles into
complete and
functional HIV
virus - Inserts viral DNA
into host DNA
pol (polymerase)
- Binds to CD4
receptors - Required for viral
fusion of the cell
env (envelope)
One of the most commonly performed confirmatory test for HIV detection is through______
WESTERN BLOT and ENZYME
BASED PCR
One of the most commonly performed confirmatory test for HIV detection is through______
WESTERN BLOT and ENZYME
BASED PCR
- It contains lots of strains which causes different types of
infection - highly tissue tropic, and infection is limited to
stratified epithelium at either cutaneous or mucosal
surfaces, usually at specific body sites - The vast majority of HPV types cause benign warts of the
skin or genital region.
HUMAN PAPILLOMAVIRUS
- of genomic organization of HPV16
ORF. P97 refers to dominant promoter. - All PVs are similar in their genetic organization and
appearance under electron microscope. URR, upstream
regulatory region. - Medically important gene that is targeted/detected is the E6
and E7.
SCHEMATIC DIAGRAM OF HPV 16 AND HPV 18
- Viral hepatitis is a serious public health problem requiring
early diagnosis and timely treatment. - A number of hepatitis viruses already have been characterized based on their molecular structure and named alphabetically as hepatitis viruses A, B, C, D, E, and G (HAV, HBV, HCV, HDV, HEV, and HGV, respectively).
- These are hepatotropic and noncytopathic in nature and
cause liver damage by immune mediated cell lysis.
HEPATITIS VIRUSES
