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MICROBIOLOGY -HONOURS 2023 Paper: CC-14 (Medical Microbiology) Full Marks : 50 CC-14
MICROBIOLOGY -HONOURS
Paper: CC-14 (Medical Microbiology)
Full Marks : 50
CC-14
1 Question
(a) Why are some parts of the respiratory tract difficult to
colonize by bacteria?
(a)
Some parts of the respiratory tract are challenging for bacteria to colonize
due to several reasons. The upper respiratory tract, including the nasal
passages and throat, has mechanisms like mucociliary clearance, which helps
trap and remove bacteria. Additionally, the respiratory tract has a lining of
mucus and antimicrobial substances that can inhibit bacterial growth. Moreover,
the presence of immune cells like macrophages and antibodies helps to defend
against bacterial invasion, making it difficult for bacteria to establish
colonies in these areas.
b) What is the cause of dental caries? Name the causative agent?
(b)
Dental caries, commonly known as tooth decay, is primarily caused by the
interaction of bacteria with sugars from the diet, leading to the production of
acids that demineralize the tooth enamel. The primary causative agent of dental
caries is Streptococcus mutans, a bacteria commonly found in the oral cavity.
When sugars are consumed, S. mutans metabolizes them, producing acids that
erode the tooth enamel, eventually leading to cavities if left untreated.
c) What are anti-microbial peptides?
(c)
Antimicrobial peptides are small proteins produced by various cells in the
body, including immune cells and epithelial cells. These peptides play a
crucial role in the innate immune system's defense against pathogens.
Antimicrobial peptides have broad-spectrum antimicrobial activity, meaning they
can target a wide range of bacteria, fungi, and viruses. They disrupt microbial
cell membranes, leading to cell death and helping to control infections.
(d) Mention how do enveloped and non-enveloped human viruses adhere
to the host cell membrane receptors.
(d)
When it comes to how enveloped and non-enveloped human viruses adhere to host
cell membrane receptors, there are differences in their mechanisms. Enveloped
viruses, like the influenza virus, typically use viral envelope proteins to
bind to specific receptors on the host cell membrane. These envelope proteins
facilitate the fusion of the viral envelope with the host cell membrane,
allowing the virus to enter the cell.
On
the other hand, non-enveloped viruses, such as the adenovirus, often use
specific proteins on their capsid (outer shell) to interact with receptors on
the host cell surface. This interaction can trigger processes that lead to the
entry of the virus into the host cell, usually through endocytosis.
e) How antibiotic resistance is related to the normal microflora of
our body? Differentiate between pathogenicity and virulence.
(e)
antibiotic resistance and our body's normal microflora. Antibiotic resistance
can develop in normal microflora when antibiotics are used inappropriately or
excessively. When antibiotics are taken, they not only target harmful bacteria
but can also affect the beneficial bacteria in our normal microflora. This
disruption can create an environment where antibiotic-resistant strains of
bacteria within the normal microflora can thrive, leading to potential
infections that are challenging to treat.
Pathogenicity
and virulence are related but have distinct meanings. Pathogenicity refers to
the ability of a microorganism to cause disease in a host, while virulence
specifically describes the severity or harmfulness of the disease caused by the
microorganism. In simpler terms, pathogenicity is the capacity to cause
disease, while virulence is the degree of harm caused by the disease.
f) Describe Widal test?
(f)
The Widal test is a diagnostic test used to detect specific antibodies in the
blood of individuals infected with certain types of bacteria that cause typhoid
fever or other enteric fevers. It helps in the diagnosis of typhoid and
paratyphoid fevers caused by Salmonella typhi and Salmonella paratyphi,
respectively.
During
the Widal test, the patient's blood serum is mixed with a solution containing
antigens derived from the Salmonella bacteria. If the patient has been exposed
to these bacteria and has developed specific antibodies against them, a visible
reaction will occur, indicating a positive result for the presence of these
antibodies.
The
test measures the levels of antibodies, including anti-O and anti-H antibodies,
which are specific to the Salmonella bacteria. The results are interpreted
based on the levels of these antibodies present in the patient's blood serum. The Widal test is an essential tool in
diagnosing and monitoring typhoid and paratyphoid fevers, especially in regions
where these diseases are prevalent. It is crucial to interpret the results
accurately and in conjunction with other clinical findings to ensure an
accurate diagnosis.
h) How docs bacterial LPS contribute to pathogenicity?
(h)
Bacterial LPS (lipopolysaccharides) contributes to pathogenicity by acting as
an endotoxin. When bacteria containing LPS are destroyed or shed, the LPS can
trigger a strong immune response in the host, leading to inflammation and
potentially harmful effects. LPS can activate the immune system, causing the
release of inflammatory mediators that can lead to symptoms of infection and
contribute to the virulence of the bacteria.
i) Distinguish between Sabin and Salk Polio Vaccine.
(i)
The Sabin and Salk polio vaccines are both used to prevent polio, but they
differ in their composition and administration. The Sabin vaccine is an oral
polio vaccine that contains weakened (attenuated) live poliovirus strains and
is administered orally. In contrast, the Salk vaccine is an inactivated polio
vaccine that contains killed poliovirus strains and is administered via
injection.
j) Define an opportunistic pathogen. Give one example.
(j)
An opportunistic pathogen is a microorganism that normally does not cause
disease in healthy individuals but can become pathogenic under certain
conditions, such as a weakened immune system or changes in the host's
environment. An example of an opportunistic pathogen is Pneumocystis jirovecii,
which can cause pneumonia in individuals with compromised immune systems.
k) Which part of the human body can be affected by Candida
infection?
(k)
Candida infections can affect various parts of the human body, with the most
common being mucous membranes and moist areas such as the mouth (oral thrush),
skin, and genital areas (vaginal yeast infections). Candida can also cause
systemic infections in immunocompromised individuals.
l) Write down two examples of normal flora found in urogenital
tract.
(l)
Two examples of normal flora found in the urogenital tract are:
1.
Lactobacillus species: These bacteria are commonly found in the vagina and help
maintain a healthy acidic environment, preventing the overgrowth of harmful
microorganisms.
2.
Escherichia coli: While some strains of E. coli can be pathogenic, certain
strains are part of the normal flora in the urogenital tract and play a role in
maintaining the microbial balance in the gut and urinary tract.
m) Name the pathogen responsible for causing Chikungunia.
m)
The pathogen responsible for causing Chikungunya is the Chikungunya virus,
which is primarily transmitted to humans through the bite of infected Aedes
mosquitoes.
n) Why antibiotics have no effect on viruses?
(n)
Antibiotics have no effect on viruses because antibiotics specifically target
bacterial cells' structures or processes that are different from those of
viruses. Viruses are not considered living organisms; they are essentially
genetic material (DNA or RNA) surrounded by a protein coat. Since viruses
replicate inside host cells using the host's cellular machinery, antibiotics,
which target bacterial cell structures like cell walls or protein synthesis,
are ineffective against viruses.
o) Why does poliomyelitis virus attack motor neurons but not sensory
neurons?
(o)
The poliomyelitis virus attacks motor neurons but not sensory neurons because
the virus has a preference for certain types of cells. In the case of
poliovirus, it has a tropism (affinity) for motor neurons in the spinal cord.
When the virus infects motor neurons, it disrupts the signals sent from the
brain to the muscles, leading to muscle weakness and paralysis. Sensory
neurons, which transmit sensory information like touch and pain, are not the
primary target of the poliovirus, explaining why it mainly affects motor
function.
2.
Question
(a) How does the influenza virus cause the symptoms associated with
flu?
(a)
The influenza virus causes the symptoms associated with flu by infecting the
respiratory tract, specifically the nose, throat, and sometimes the lungs. The
virus enters the body through the respiratory route, usually via droplets from
coughs or sneezes of an infected person. Once inside the body, the virus
replicates rapidly, leading to inflammation and damage to the respiratory
epithelium. This process triggers the body's immune response, resulting in
symptoms such as fever, cough, sore throat, muscle aches, fatigue, and
sometimes respiratory issues. (b) What are the main
routes of transmission of poliovirus? What are the symptoms?
(b)
The main routes of transmission of the poliovirus are through the fecal-oral
route and respiratory droplets. The symptoms of poliovirus infection can vary
from asymptomatic or mild flu-like symptoms to more severe cases where the
virus attacks the nervous system, leading to paralysis, particularly in the
legs.
(c) Write down the causative agent, symptoms and treatment for Japanese Encephalitis
(c)
Japanese Encephalitis is caused by the Japanese encephalitis virus (JEV), which
is transmitted through mosquito bites, particularly the Culex species. Symptoms
of Japanese Encephalitis include fever, headache, neck stiffness, stupor,
disorientation, coma, tremors, and paralysis. Treatment for Japanese
Encephalitis mainly involves supportive care to manage symptoms. There is also
a vaccine available for Japanese Encephalitis, which is recommended for travellers
to areas where the disease is endemic.
3.
Question
(a) Treatment of fungal infections generally has been less
successful than the bacteria Why?
(a)
Treatment of fungal infections generally has been less successful than bacterial
infections because fungi are eukaryotic organisms like humans, making it
challenging to find antifungal drugs that target the fungi without harming
human cells. This similarity in cellular structure makes it harder to develop
medications that specifically target fungal cells without causing significant
side effects in the patient.
(b) Name two antifungal drugs.
(b)
Two antifungal drugs are Fluconazole and Amphotericin B.
(c) Write the mechanism of action of Amantadine.
(c)
The mechanism of action of Amantadine involves blocking the action of the M2
protein of the influenza A virus. By inhibiting this protein, Amantadine
prevents the virus from uncoating and releasing its genetic material into the
host cell, thereby stopping viral replication.
(d) What is meant by oral thrush infection?
(d)
Oral thrush infection, also known as oral candidiasis, is a fungal infection
caused by the overgrowth of Candida yeast in the mouth and throat. It appears
as white patches on the tongue, inner cheeks, roof of the mouth, and sometimes
the throat. Oral thrush is common in infants, older adults, and individuals
with weakened immune systems. Treatment usually involves antifungal medications
in the form of oral rinses or lozenges to eliminate the fungal infection.
4.
Question
(a) Compare and contrast between amoebic dysentery and giardiasis.
(a)
Amoebic dysentery and giardiasis are both gastrointestinal infections caused by
different organisms and exhibit some differences:
-
Amoebic dysentery is caused by the parasite Entamoeba histolytica, while
giardiasis is caused by the parasite Giardia lamblia.
-
Symptoms of amoebic dysentery include bloody diarrhea, abdominal pain, and
fever, whereas giardiasis typically presents with diarrhea, gas, greasy stools,
and abdominal cramps.
-
Both infections are transmitted through contaminated food or water, but amoebic
dysentery can also be transmitted through direct contact with feces.
-
Treatment for amoebic dysentery usually involves medications like
metronidazole, while giardiasis can be treated with drugs like metronidazole or
tinidazole.
(b) Discuss the mechanism of resistance for the following
antibiotics :
(i) Penicillin
(ii) Streptomycin.
(b)
The mechanisms of resistance for Penicillin and Streptomycin are as follows:
(i)
Penicillin: Bacteria can develop resistance to penicillin through several
mechanisms, with the most common being the production of beta-lactamase
enzymes. These enzymes inactivate penicillin by breaking down its beta-lactam
ring structure, rendering the antibiotic ineffective. Bacteria can also develop
resistance by modifying the target site of penicillin, such as
penicillin-binding proteins, making it harder for the antibiotic to bind and
inhibit bacterial cell wall synthesis.
(ii)
Streptomycin: Resistance to streptomycin can occur through different
mechanisms, including the modification of the bacterial ribosomal target site.
Bacteria can alter the ribosomal binding site for streptomycin, reducing the
antibiotic's ability to bind and inhibit protein synthesis. Additionally, some
bacteria can produce enzymes that modify streptomycin, rendering it inactive.
Resistance can also develop through decreased uptake of the antibiotic into the
bacterial cell or increased efflux of the drug out of the cell, reducing its
concentration and effectiveness.
5. Question 5
(a) Name two antibacterial drugs of each of the following :
(i) Cell wall synthesis inhibition.
(ii) Protein synthesis inhibition.
(iii) Nucleic acid synthesis inhibition.
(iv) Inhibitor of Metabolism.
a)
Here are two antibacterial drugs for each of the following mechanisms of
action:
(i)
Cell wall synthesis inhibition:
1.
Penicillin
2.
Vancomycin
(ii)
Protein synthesis inhibition:
1.
Erythromycin
2.
Tetracycline
(iii)
Nucleic acid synthesis inhibition:
1.
Ciprofloxacin
2.
Rifampin
(iv)
Inhibitor of Metabolism:
1.
Trimethoprim
2.
Sulfamethoxazole
(b) Write down the
symptoms and prophylaxis of Kala-azar.
(b.)
Kala-azar, also known as visceral leishmaniasis, is a serious parasitic disease
caused by the protozoan parasite Leishmania donovani. The symptoms of Kala-azar
include prolonged fever, weight loss, fatigue, anemia, and enlargement of the
spleen and liver, which can lead to a potbelly appearance.
Prophylaxis
for Kala-azar involves preventive measures to reduce the risk of infection,
such as:
1.
Avoiding travel to areas where Kala-azar is endemic.
2.
Using insect repellents and wearing protective clothing to prevent sandfly
bites.
3.
Sleeping under insecticide-treated bed nets.
4.
Early diagnosis and treatment of cases to prevent the spread of the disease
within communities.
6. Question
(a) State the mode of action
of:
(i) Quinolone
(ii) Streptomycin.
(b) How docs Hepatitis A and 8 virus differ from each other?
(c) Describe schematically PCR-technique for the detection of any
pathogen of your interest.
(a)
Here are the modes of action of the antibiotics you mentioned:
(i)
Quinolone: Quinolones act by inhibiting the enzymes DNA gyrase and
topoisomerase IV, which are essential for bacterial DNA replication and repair.
By interfering with these enzymes, quinolones prevent DNA synthesis and
ultimately lead to bacterial cell death.
(ii)
Streptomycin: Streptomycin works by binding to the bacterial ribosome and
inhibiting protein synthesis. It specifically targets the 30S subunit of the
bacterial ribosome, disrupting the translation process and causing the
production of faulty proteins, which leads to bacterial cell death.
(b)
Hepatitis A virus (HAV) and Hepatitis B virus (HBV) differ in several ways:
-
Transmission: HAV is primarily transmitted through the fecal-oral route, often
due to contaminated food or water, while HBV is transmitted through exposure to
infected blood or body fluids.
-
Chronicity: HAV infection is typically acute and does not lead to chronic
infection, whereas HBV can result in chronic hepatitis, which may lead to
long-term liver complications.
-
Vaccine Availability: There is a vaccine available for HAV, providing immunity
against the virus, while there is also a vaccine for HBV.
-
Treatment: The treatment approaches for HAV and HBV differ, with HBV having
specific antiviral medications available for management.
(c)
PCR (Polymerase Chain Reaction) is a molecular biology technique used to
amplify a specific segment of DNA. Here is a schematic representation of the
PCR technique for the detection of a pathogen:
1.
Denaturation: The DNA sample containing the pathogen's DNA is heated to
separate the double-stranded DNA into single strands.
2.
Annealing: Primers (short DNA sequences that are complementary to the target
pathogen DNA) are added. These primers bind to the specific sequences flanking
the target DNA region.
3.
Extension: DNA polymerase extends the primers by adding nucleotides to create a
new DNA strand complementary to the target pathogen DNA.
4.
Amplification: The process is repeated through multiple cycles (usually around
30 cycles), resulting in exponential amplification of the target DNA region.
5.
Detection: The amplified DNA can be visualized using gel electrophoresis or
other detection methods to confirm the presence of the pathogen's DNA.
7. Write short notes on following
:
(a) Erythrocytic cycle of Plasmodi11m
(b) Polymyxin antibiotics
(c) 'Viremia' in the context of paralytic polio
(d) Cholera toxin
(e) Nosocomial infection
(f). Sandwich ELISA.
(a)
Erythrocytic cycle of Plasmodium:
-
The erythrocytic cycle of Plasmodium refers to the stage of the malaria
parasite's life cycle where it infects and replicates within red blood cells.
-
During this cycle, the parasite undergoes several stages, including invasion of
red blood cells, replication, and eventual bursting of the infected cells,
releasing more parasites into the bloodstream.
-
The cycle is responsible for the recurring fevers and symptoms associated with
malaria and plays a crucial role in the spread of the disease.
(b)
Polymyxin antibiotics:
-
Polymyxin antibiotics are a group of antibiotics that are effective against
certain Gram-negative bacteria.
-
They work by disrupting the bacterial cell membrane, leading to leakage of
cellular contents and ultimately bacterial cell death.
-
Polymyxins are often used as a last resort for treating multidrug-resistant
infections but can have significant side effects, especially on the kidneys and
nervous system.
(c)
'Viremia' in the context of paralytic polio:
-
Viremia refers to the presence of a virus in the bloodstream. In the context of
paralytic polio, viremia indicates the spread of the poliovirus through the
blood, allowing it to reach and infect the central nervous system.
-
The presence of the virus in the blood during viremia can lead to the
development of paralytic polio, where the virus affects the motor neurons in
the spinal cord, causing paralysis.
(d)
Cholera toxin:
-
Cholera toxin is a protein complex produced by the bacterium Vibrio cholerae,
responsible for the severe watery diarrhea characteristic of cholera
infections.
-
The toxin binds to cells in the intestines, leading to the activation of
adenylate cyclase and subsequent increase in cyclic AMP levels within the
cells.
-
This elevation of cyclic AMP disrupts ion transport in the intestines, causing
the secretion of large amounts of fluid into the gut, resulting in the profuse
watery diarrhea seen in cholera.
(e)
Nosocomial infection:
-
Nosocomial infections are infections acquired in a healthcare setting, such as
hospitals or clinics, by patients receiving medical treatment.
-
These infections can be caused by a variety of pathogens, including bacteria,
viruses, and fungi, and are often associated with invasive procedures,
contaminated medical equipment, or poor infection control practices.
-
Preventing nosocomial infections requires strict adherence to infection control
protocols, proper hygiene practices, and surveillance to identify and manage
outbreaks.
(f)
Sandwich ELISA:
-
Sandwich ELISA (Enzyme-Linked Immunosorbent Assay) is a type of ELISA used to
detect and quantify the presence of an antigen in a sample.
-
In this assay, the antigen is sandwiched between two antibodies: a capture
antibody immobilized on the surface and a detection antibody linked to an
enzyme.
-
The enzyme-linked antibody produces a signal when it binds to the antigen,
allowing for the detection and quantification of the antigen in the sample.
Monday, April 29, 2024
B.Sc (HONOURS) MICROBIOLOGY (CBCS STRUCTURE) CC-14: MEDICAL MICROBIOLOGY (THEORY) SEMESTER –6 MCB-A-CC-6-14-TH Unit 7 Antimicrobial agents: General characteristics and mode of action
Unit 7 Antimicrobial agents: General characteristics and
mode of action
Amphotericin B is a polyene
antifungal drug. It binds to ergosterol, a key component of fungal cell
membranes, and forms channels or pores. These pores disrupt the integrity of
the cell membrane, leading to leakage of cellular contents and ultimately
causing cell death.
Griseofulvin, on the other hand,
is an antifungal medication that belongs to the class of drugs known as
antifungal antibiotics. It works by inhibiting the synthesis of fungal cell
walls. Specifically, it interferes with the assembly of microtubules, which are
essential for the growth and replication of fungal cells. By disrupting this
process, griseofulvin prevents the fungus from spreading and helps to eliminate
the infection.
Amphotericin B can have some side
effects. The most common ones include fever, chills, nausea, vomiting, and
headache. It can also cause kidney damage, so it's important to monitor kidney
function during treatment. Some people may experience allergic reactions or
have issues with their blood cells. It's always best to talk to a healthcare
professional if you have any concerns or questions about specific side effects.
Amantadine is primarily used
to treat influenza A virus infections. It works by blocking a protein called
M2 ion channel in the viral envelope. By inhibiting this protein, Amantadine
prevents the release of viral genetic material into the host cell, ultimately
stopping the replication of the virus.
Acyclovir, on the other hand, is
commonly used to treat herpes virus infections, including genital herpes, cold
sores, and shingles. It is a nucleoside analogue that gets incorporated into
the viral DNA during replication. Once incorporated, Acyclovir disrupts the
viral DNA synthesis, preventing the virus from replicating and spreading.
Amantadine blocks the M2 ion
channel by binding to it and preventing the flow of ions, like protons, into
the viral particle. This disruption of ion flow inhibits the release of viral
genetic material into the host cell, which is necessary for the virus to
replicate. By blocking the M2 ion channel, Amantadine helps to stop the spread
of the influenza A virus.
Amantadine typically starts
working within a few hours to a couple of days after starting treatment.
However, it's important to note that the exact timeframe can vary depending on
the individual and the specific condition being treated. It's always best to
follow the instructions provided by your healthcare professional and give the
medication some time to take effect.
Amantadine can interact with
certain medications, so it's important to let your healthcare provider know
about all the medications you're taking. Some medications that may interact
with Amantadine include anticholinergic drugs, such as certain medications for
Parkinson's disease or certain antihistamines. Additionally, Amantadine may
enhance the effects of certain medications that affect the central nervous
system, like sedatives or alcohol.
Different terms related to
antibiotic resistance. Let's break them down:
1. Azidothymidine (AZT): While
AZT is not an antibiotic, it is an antiviral medication used to treat HIV/AIDS.
It works by inhibiting the reverse transcriptase enzyme, which is crucial for
the replication of the virus. By blocking this enzyme, AZT helps to slow down
the progression of HIV infection.
2. Antibiotic resistance: This
refers to the ability of bacteria or other microorganisms to resist the effects
of antibiotics. Over time, bacteria can develop mechanisms to survive and grow
in the presence of antibiotics, making the medications less effective in
treating infections.
3. MDR (Multi-Drug Resistant):
MDR bacteria are those that have become resistant to multiple antibiotics,
making them more challenging to treat. These bacteria have developed mechanisms
to withstand the effects of multiple drugs, limiting treatment options.
4. XDR (Extensively Drug
Resistant): XDR bacteria are even more concerning as they are resistant to a
wide range of antibiotics, including those considered to be the last line of
defense. This makes infections caused by XDR bacteria extremely difficult to
treat.
5. MRSA (Methicillin-Resistant
Staphylococcus aureus): MRSA is a type of bacteria that has developed
resistance to many antibiotics, including methicillin and other
penicillin-related antibiotics. It can cause difficult-to-treat infections,
particularly in healthcare settings.
6. NDM-1 (New Delhi
metallo-beta-lactamase-1): NDM-1 is an enzyme produced by certain bacteria that
confers resistance to a broad range of antibiotics, including carbapenems,
which are often considered the last resort for treating severe infections.
1. Azidothymidine (AZT): While
AZT is not an antibiotic, it is an antiviral medication used to treat
HIV/AIDS. It works by inhibiting the reverse transcriptase enzyme, which is
crucial for the replication of the virus. By blocking this enzyme, AZT helps to
slow down the progression of HIV infection.
2. Antibiotic resistance: This
refers to the ability of bacteria or other microorganisms to resist the effects
of antibiotics. Over time, bacteria can develop mechanisms to survive and grow
in the presence of antibiotics, making the medications less effective in
treating infections.
3. MDR (Multi-Drug Resistant):
MDR bacteria are those that have become resistant to multiple antibiotics,
making them more challenging to treat. These bacteria have developed mechanisms
to withstand the effects of multiple drugs, limiting treatment options.
4. XDR (Extensively Drug
Resistant): XDR bacteria are even more concerning as they are resistant to a
wide range of antibiotics, including those considered to be the last line of
defense. This makes infections caused by XDR bacteria extremely difficult to
treat.
5. MRSA (Methicillin-Resistant
Staphylococcus aureus): MRSA is a type of bacteria that has developed
resistance to many antibiotics, including methicillin and other
penicillin-related antibiotics. It can cause difficult-to-treat infections,
particularly in healthcare settings.
6. NDM-1 (New Delhi
metallo-beta-lactamase-1): NDM-1 is an enzyme produced by certain bacteria that
confers resistance to a broad range of antibiotics, including carbapenems,
which are often considered the last resort for treating severe infections.
AZT, also known as zidovudine,
is an antiretroviral drug used in the treatment of HIV/AIDS. It belongs to
a class of medications called nucleoside reverse transcriptase inhibitors
(NRTIs). AZT works by inhibiting the reverse transcriptase enzyme, which is
necessary for the replication of the HIV virus.
When HIV infects a person, it
enters their immune cells and uses the reverse transcriptase enzyme to convert
its RNA into DNA. This DNA is then integrated into the host cell's DNA,
allowing the virus to reproduce. AZT works by blocking the reverse transcriptase
enzyme, preventing the virus from replicating and slowing down the progression
of the disease.
AZT is typically used in
combination with other antiretroviral drugs to form a highly active
antiretroviral therapy (HAART) regimen. This combination approach helps to
reduce the viral load in the body, improve the immune system, and prolong the
lifespan of individuals living with HIV/AIDS.
It's important to note that AZT,
like any medication, can have side effects. Common side effects may include
nausea, vomiting, headache, fatigue, and anemia. However, the benefits of AZT
in managing HIV/AIDS often outweigh the potential side effects.
They can develop antibiotic
resistance through a few different ways:
1. Mutation: Bacteria can undergo
genetic mutations that give them the ability to withstand the effects of
certain antibiotics. These mutations can occur naturally over time or be
acquired from other resistant bacteria.
2. Horizontal gene transfer:
Bacteria can share their genetic material with other bacteria through processes
like conjugation, transformation, or transduction. This means that a bacterium
that is already resistant to an antibiotic can pass on its resistance genes to
other bacteria, allowing them to become resistant as well.
3. Overuse and misuse of
antibiotics: When antibiotics are used too often or not used properly, it can
create an environment where bacteria are exposed to the drugs frequently. This
selective pressure can favor the survival and growth of resistant bacteria,
leading to the development of antibiotic resistance.
4. Evolutionary pressure:
Bacteria have a remarkable ability to adapt and evolve. When exposed to
antibiotics, the bacteria that are naturally resistant or acquire resistance
genes have a survival advantage. Over time, these resistant bacteria become more
prevalent in a population.
There are a few key factors
that contribute to the development of antibiotic resistance:
1. Natural selection: Bacteria
reproduce rapidly, and with each generation, there is a chance for genetic
mutations to occur. Sometimes, these mutations can provide bacteria with the
ability to resist the effects of antibiotics. When antibiotics are used, they
kill the susceptible bacteria, but the resistant ones survive and multiply,
passing on their resistance genes to future generations.
2. Overuse and misuse of
antibiotics: When antibiotics are used too frequently or inappropriately, it
puts selective pressure on bacteria. This means that the bacteria that have
natural or acquired resistance to antibiotics have a survival advantage. Over
time, these resistant bacteria become more prevalent in a population, making
the antibiotics less effective.
3. Transmission of resistance
genes: Bacteria can also acquire resistance genes from other bacteria through a
process called horizontal gene transfer. This can happen through mechanisms
like conjugation, where genetic material is exchanged between bacteria, or
through the uptake of DNA from the environment. This transfer of resistance
genes allows bacteria to quickly develop resistance to multiple antibiotics.
Multi-Drug Resistant, refers
to bacteria or other microorganisms that have developed resistance to
multiple types of antibiotics. This means that they are not affected by the
usual medications that would normally be used to treat infections caused by
those bacteria.
MDR can occur due to several
reasons:
1. Overuse and misuse of
antibiotics: Similar to antibiotic resistance, the inappropriate use of
antibiotics can contribute to the development of MDR. When antibiotics are used
excessively or not taken as prescribed, it provides an opportunity for bacteria
to adapt and become resistant to multiple drugs.
2. Poor infection control: In
settings such as hospitals, clinics, or long-term care facilities, the spread
of MDR organisms can occur if proper infection control practices are not
followed. This can lead to the transmission of resistant bacteria between
patients, making it more challenging to treat infections effectively.
3. Global travel and migration:
With increased global travel and migration, MDR organisms can spread across
different regions and countries. This can result in the introduction of
resistant strains into new populations, making it difficult to control their
spread.
XDR stands for Extensively Drug
Resistant, and it's even more serious than MDR. When bacteria or other
microorganisms are classified as XDR, it means they are resistant to a wide
range of antibiotics, including those considered as last-resort treatments.
XDR bacteria have developed
resistance not only to multiple classes of antibiotics but also to some of the
most potent ones available. This makes them extremely difficult to treat and
can lead to severe infections that are challenging to control.
Similar to MDR, the causes of XDR
include overuse and misuse of antibiotics, poor infection control practices,
and global spread. However, XDR organisms have acquired additional resistance
mechanisms, making them even more formidable.
The consequences of XDR
infections can be devastating, as they limit treatment options and increase the
risk of complications and mortality. In some cases, infections caused by XDR
bacteria may require specialized antibiotics or combination therapies that have
more potential side effects or are less effective.
MRSA stands for
Methicillin-Resistant Staphylococcus aureus. Staphylococcus aureus is a type of
bacteria commonly found on the skin or in the nose of healthy individuals.
However, when it becomes resistant to methicillin and other antibiotics, it can
cause serious infections that are difficult to treat.
MRSA infections can occur in both
healthcare settings (HA-MRSA) and in the community (CA-MRSA). In healthcare
settings, MRSA can spread through contact with contaminated surfaces, medical
equipment, or from person to person. In the community, MRSA can be transmitted
through close skin-to-skin contact or by sharing personal items like towels or
razors.
Symptoms of MRSA infections can
vary depending on the site of infection, but they often include skin infections
such as boils, abscesses, or cellulitis. In more severe cases, MRSA can cause
bloodstream infections, pneumonia, or surgical site infections.
Treating MRSA can be challenging
because it is resistant to many commonly used antibiotics. However, there are
still effective treatment options available, such as certain antibiotics or a
combination of medications. In some cases, drainage of abscesses or surgical
intervention may be necessary.
Preventing MRSA infections
involves practicing good hygiene, such as regular handwashing, keeping wounds
clean and covered, and avoiding sharing personal items. In healthcare settings,
infection control measures like proper hand hygiene, isolation precautions, and
environmental cleaning are crucial in preventing the spread of MRSA.
Monday, April 22, 2024
B.Sc (HONOURS) MICROBIOLOGY (CBCS STRUCTURE) CC-14: MEDICAL MICROBIOLOGY (THEORY) SEMESTER –6 MCB-A-CC-6-14-TH (Viral diseases)
Thursday, April 18, 2024
B.Sc (HONOURS) MICROBIOLOGY (CBCS STRUCTURE) CC-14: MEDICAL MICROBIOLOGY (THEORY) SEMESTER –6 MCB-A-CC-6-14-TH
Helicobacter pylori
Helicobacter pylori is a
bacterium that infects the stomach lining and can cause various
gastrointestinal conditions. Here's some information for you:
Symptoms: Helicobacter pylori
infection can lead to several symptoms, including stomach pain, bloating,
nausea, vomiting, loss of appetite, and in some cases, peptic ulcers or
gastritis. However, not everyone infected with H. pylori will experience symptoms.
Mode of Transmission: The exact
mode of transmission is not fully understood, but it is believed that H. pylori
is primarily transmitted through oral-oral or fecal-oral routes. It can spread
through close contact with an infected person, consuming contaminated food or
water, or poor hygiene practices.
Prophylaxis: Preventing H. pylori
infection involves adopting good hygiene practices and taking certain
precautions. Here are some measures to consider:
- Wash your hands thoroughly with
soap and clean water, especially before eating or preparing food.
- Avoid consuming food or water
that may be contaminated.
- Cook food thoroughly,
especially meat and seafood.
- Practice safe food handling and
storage.
- Avoid sharing utensils, cups,
or other personal items with someone who may be infected.
Treatment for H. pylori infection
usually involves a combination of antibiotics and acid-suppressing medications.
It's essential to follow the prescribed treatment regimen and complete the full
course of antibiotics to effectively eliminate the infection.
B.Sc (HONOURS) MICROBIOLOGY (CBCS STRUCTURE) CC-14: MEDICAL MICROBIOLOGY (THEORY) SEMESTER –6 MCB-A-CC-6-14-TH
BACTERIAL DISEASES
Streptococcus pyogenes,
Streptococcus pyogenes, also known as Group A Streptococcus, is a bacterium that can cause a range of respiratory infections. One of the most common infections it causes is strep throat, which is characterized by a sore throat, difficulty swallowing, and swollen tonsils. Other respiratory infections caused by this bacterium include tonsillitis, sinusitis, and ear infections.
The mode of transmission for Streptococcus pyogenes is primarily through respiratory droplets. When an infected person coughs or sneezes, tiny droplets containing the bacteria can be released into the air. If these droplets are inhaled by others, they can become infected. Additionally, direct contact with infected saliva or nasal secretions can also spread the bacteria.
To prevent the spread of Streptococcus pyogenes, practicing good hygiene is key. This includes washing your hands regularly with soap and water, especially before eating or touching your face. Covering your mouth and nose with a tissue or your elbow when coughing or sneezing can help prevent the release of respiratory droplets. Avoiding close contact with individuals who are known to have a streptococcal infection is also important.
Haemophilus influenzae
Haemophilus influenzae is a bacterium that can cause respiratory infections. Here's some more info:
Symptoms: When infected with Haemophilus influenzae, you might experience symptoms like cough, fever, difficulty breathing, chest pain, and sometimes a sore throat. These symptoms can vary depending on the specific respiratory infection caused by the bacterium.
Mode of Transmission: Haemophilus influenzae is mainly spread through respiratory droplets. So, when someone who's infected coughs or sneezes, tiny droplets containing the bacterium can be released into the air. If you breathe in those droplets or come into direct contact with infected respiratory secretions, you can get infected too.
Prophylaxis: To prevent the spread of Haemophilus influenzae, it's important to practice good hygiene. Wash your hands frequently with soap and water, especially before eating or touching your face. When you cough or sneeze, cover your mouth and nose with a tissue or your elbow. And try to avoid close contact with people who are known to have a Haemophilus influenzae infection.
Mycobacterium tuberculosis:
Mycobacterium tuberculosis, also known as TB, is a respiratory disease caused by a bacteria. Here's some more info:
Symptoms: TB can cause symptoms like a persistent cough, chest pain, coughing up blood, fatigue, weight loss, and night sweats. It can affect the lungs (pulmonary TB) or other parts of the body (extrapulmonary TB).
Mode of Transmission: TB is usually spread through the air when someone with active TB coughs or sneezes, releasing tiny droplets containing the bacteria. Breathing in these droplets can lead to infection. Close and prolonged contact with an infected person increases the risk of transmission.
Prophylaxis: Taking preventive measures is important to reduce the risk of TB. If you've been in close contact with someone who has active TB, your healthcare provider might recommend prophylactic treatment with antibiotics to prevent infection. Vaccination with the BCG vaccine is also available in some countries and can provide partial protection against severe forms of TB, especially in children.
Escherichia coli, a gastrointestinal disease commonly known as E. coli:
E. coli is a type of bacteria that can cause various gastrointestinal illnesses. Here are some more details:
Symptoms: The symptoms of E. coli infection can vary depending on the strain and severity of the infection. Common symptoms include diarrhea (often bloody), abdominal pain or cramping, nausea, and vomiting. Some individuals may also experience fever and fatigue.
Mode of Transmission: E. coli is usually transmitted through contaminated food or water. Consuming undercooked or raw meat, unpasteurized dairy products, contaminated produce, or contaminated water can lead to infection. Person-to-person transmission can also occur, especially in settings with poor hygiene, such as daycare centers or nursing homes.
Prophylaxis: Prevention is key when it comes to E. coli infections. Here are some preventive measures you can take:
1. Practice good hygiene: Wash your hands thoroughly with soap and water before handling food, after using the bathroom, and after changing diapers. Encourage others to do the same.
2. Cook food properly: Cook meat, especially ground beef, to a safe internal temperature. Avoid consuming raw or undercooked foods, including eggs and unpasteurized dairy products.
3. Practice safe food handling: Wash fruits and vegetables thoroughly before eating or cooking. Avoid cross-contamination by keeping raw meat separate from other foods and using separate cutting boards and utensils.
4. Drink safe water: Ensure that your drinking water comes from a safe source. If you're unsure about the water quality, consider using bottled water or boiling tap water before consumption.
Salmonella typhi, a gastrointestinal disease commonly known as typhoid fever:
Symptoms: The symptoms of typhoid fever can be quite severe. They typically include high fever, headache, abdominal pain, loss of appetite, and a rash. Some individuals may also experience constipation or diarrhea.
Mode of Transmission: Typhoid fever is primarily transmitted through the ingestion of food or water contaminated with the Salmonella typhi bacteria. This can happen when food is handled by someone who carries the bacteria or when water sources are contaminated with sewage containing the bacteria.
Prophylaxis: Preventing typhoid fever involves taking certain precautions:
1. Practice good hygiene: Wash your hands thoroughly with soap and water before eating, after using the bathroom, and when handling food. Encourage others to do the same.
2. Drink safe water: Ensure that your drinking water comes from a safe source. If you're unsure about the water quality, consider using bottled water or boiling tap water before consumption.
3. Eat safe food: Be cautious about the food you consume, especially when traveling to areas with a higher risk of typhoid fever. Avoid raw or undercooked foods, particularly meat, seafood, and eggs. Opt for fruits and vegetables that you can peel yourself.
4. Get vaccinated: Consider getting vaccinated against typhoid fever, especially if you're traveling to regions where the disease is prevalent or if you work in a high-risk environment.
Vibrio cholerae and gastrointestinal diseases.
Vibrio cholerae is a bacterium that causes the infectious disease known as cholera. Here's some information for you:
Symptoms: Cholera typically presents with severe watery diarrhea, vomiting, and dehydration. The diarrhea can be so profuse that it leads to rapid fluid loss, which can be life-threatening if not treated promptly.
Mode of Transmission: Vibrio cholerae is primarily transmitted through contaminated food and water. Consuming food or water contaminated with the bacterium can lead to infection. It can also spread through poor sanitation practices, such as improper disposal of feces or sewage.
Prophylaxis: Preventing cholera involves practicing good hygiene and taking precautions when it comes to food and water. Here are some measures to consider:
- Drink clean and safe water, such as boiled or treated water.
- Avoid consuming raw or undercooked seafood, as it can be a source of Vibrio cholerae.
- Wash your hands thoroughly with soap and clean water, especially before eating or preparing food.
- Maintain proper sanitation and hygiene practices, including proper sewage disposal.