The choice of the antimicrobial used for the treatment of an infection is influenced by several factor: the age of the patient, the site of infection, immune status of the patient, efficacy of the drug, the profile of adverse effects, the prevalence of anti-microbial resistance and the concomitant presence of other systemic diseases or organ dysfunction.
The cephalosporins include three generations of agents. The second generation extends the antimicrobial spectrum of the first generation to include wide range of gram negative rods and Pseudomonas.
The -lactams act by inhibiting the incorporation of peptidoglycon into the bacterial cell wall. Penicilin G still remains the drug of choice for syphilis, meningococci, clostridia and pneumococcous. Ampicillin has an extended spectrum of activity aganst gram negative rods(Salmonella, Hemophilus influenzae). Penicillinase-resistant penicilins are the drugs of choice for infections due to -lactamase producing staphylococci. Piperacillin and ticarcillin are antipseudomonal penicillins.
Thursday, February 17, 2011
Wednesday, February 9, 2011
Diagnostic methods in infectious diseases
Microbiologic confirmation of an infectious diseses may be obtained by direct demonstration of the organism, by growing the organism in culture or by serologic method.
Direct demonstration of an infective agent may be:
By direct microscopy: India ink preparation(cryptococi), dark ground illumination(vibrio spirochestes), KOH preparation(dermatophytes) and wet wount(stool parasites).
By staining:Gram stain(malaria),Giemsa stain(chlamydia), Ziehl-Nielsen stain(acid-fast bacilli), silver stains(pneumocystis).
By antigen detection using latex agglutination teste. (meningococcus, pneumcococcus) and enzyme immunoassay.
Culture method: Proper collection technique(for clinical specimen), suitable transport and culture media and optimal growth conditions may be requuired for fastidious organisms(such as anaerobes), phenotyphic characterization may be done and antibiotic sensitivity determined after culture of the organism.
Serologic method: This method may be the only method for diagnosing viral, rickettisal, chalamydial and mycoplasma infections. Serology also provides supportive evidnce for certain bacterial infections( also for streptococci, widal for typhoid).
Direct demonstration of an infective agent may be:
By direct microscopy: India ink preparation(cryptococi), dark ground illumination(vibrio spirochestes), KOH preparation(dermatophytes) and wet wount(stool parasites).
By staining:Gram stain(malaria),Giemsa stain(chlamydia), Ziehl-Nielsen stain(acid-fast bacilli), silver stains(pneumocystis).
By antigen detection using latex agglutination teste. (meningococcus, pneumcococcus) and enzyme immunoassay.
Culture method: Proper collection technique(for clinical specimen), suitable transport and culture media and optimal growth conditions may be requuired for fastidious organisms(such as anaerobes), phenotyphic characterization may be done and antibiotic sensitivity determined after culture of the organism.
Serologic method: This method may be the only method for diagnosing viral, rickettisal, chalamydial and mycoplasma infections. Serology also provides supportive evidnce for certain bacterial infections( also for streptococci, widal for typhoid).
Friday, February 4, 2011
Fever
Fever of more than three weeks duration remaining undiagnosed after a week of hospitalization is defined as pyrexia of unknown origin (PUO).
PUO may be due to the infections, malignancy, inflammatory diseases, drugs or factitious. Infections are the leading causes of PUO tuberculosis often extrapulmonary, HIV infection, infective endocarditis, prolonged mononucleosis, intraabdominal abscess and fungal infections.
Malignancies associated with PUO are lymphomas, leukemia, renal cell carcinoma and hepatoma. Immunoinflammatory causes of PUO include SLE and adult Still’s diseases.
A proper detailed history and physical examination is critical in estabilishing a dignosis and for planing investigations. The pattern of fever is seldom diagnostic by itself. Drug history, occupational hisory and sexual practices are important areas that need to be investigated.
Routine haematologic and urinary investigations, serum chemistry and chest X-ray are important investigations in all patients. A markedly elevated ESR may indicate an infection or immunoinflammatory diseases, temporal athritis, Still’s diseases. US/CT may be obtained for evaluating hepatobiliary, renal, retroperitoneal and pelvic sources of PUO and for screening for occult primaries. An echocardiogram may be ordered if endocarditis is suspected. Biopsy of the bone marrow or liver may be useful if the non-invasive investigations do not yield a definitive diagnosis.
In the absence of a definite diagnosis, a therapeutic trial of antitubercular therapy may be instituted for six weeks.
Causes of prolonged fever
• Infections
o Polygenic infection: pyogenic abscess, cholangitis, pelvic abscess, diverticular abscess, thermbophlebitis.
o Vascular infection: Infective endocartitis, infected vascular access devices.
o Chronic granulomatious infection: Tuberculosis, atypical mycobacterial infections, fungal infection.
o Other prolonged bacterial and rickettisial illnesses: Brucellosis, chronic meningococcemia.
• Immunoinflammatory diseases: Systemic lumps erythematosus, juvenile rheumatoid arthritis(stills diseases), vasculitis including giant cell arthritis.
• Neoplasms: Primary (renal, pancreas, hepatic, lung, colon), secondary(hepatic secondaries), lymphoid neoplasms(lymphomas).
• Granulomatous conditions: Sarcoidosis.
• Metabolic and familial conditions: Familial Mediterranean fever, Fabry’s diseases.
• Drug induced fever
• Factitious fever
• Undiagnosed fever.
PUO may be due to the infections, malignancy, inflammatory diseases, drugs or factitious. Infections are the leading causes of PUO tuberculosis often extrapulmonary, HIV infection, infective endocarditis, prolonged mononucleosis, intraabdominal abscess and fungal infections.
Malignancies associated with PUO are lymphomas, leukemia, renal cell carcinoma and hepatoma. Immunoinflammatory causes of PUO include SLE and adult Still’s diseases.
A proper detailed history and physical examination is critical in estabilishing a dignosis and for planing investigations. The pattern of fever is seldom diagnostic by itself. Drug history, occupational hisory and sexual practices are important areas that need to be investigated.
Routine haematologic and urinary investigations, serum chemistry and chest X-ray are important investigations in all patients. A markedly elevated ESR may indicate an infection or immunoinflammatory diseases, temporal athritis, Still’s diseases. US/CT may be obtained for evaluating hepatobiliary, renal, retroperitoneal and pelvic sources of PUO and for screening for occult primaries. An echocardiogram may be ordered if endocarditis is suspected. Biopsy of the bone marrow or liver may be useful if the non-invasive investigations do not yield a definitive diagnosis.
In the absence of a definite diagnosis, a therapeutic trial of antitubercular therapy may be instituted for six weeks.
Causes of prolonged fever
• Infections
o Polygenic infection: pyogenic abscess, cholangitis, pelvic abscess, diverticular abscess, thermbophlebitis.
o Vascular infection: Infective endocartitis, infected vascular access devices.
o Chronic granulomatious infection: Tuberculosis, atypical mycobacterial infections, fungal infection.
o Other prolonged bacterial and rickettisial illnesses: Brucellosis, chronic meningococcemia.
• Immunoinflammatory diseases: Systemic lumps erythematosus, juvenile rheumatoid arthritis(stills diseases), vasculitis including giant cell arthritis.
• Neoplasms: Primary (renal, pancreas, hepatic, lung, colon), secondary(hepatic secondaries), lymphoid neoplasms(lymphomas).
• Granulomatous conditions: Sarcoidosis.
• Metabolic and familial conditions: Familial Mediterranean fever, Fabry’s diseases.
• Drug induced fever
• Factitious fever
• Undiagnosed fever.
Friday, January 28, 2011
Infection and immunity:
Infection and immunity: The result of any infection depends partly on the virulence and numbers of the invading organisms and partly on the state of the patients defences against them. The state of defences depends upon the two factors: the degree of natural immunity inherited from the parents, which may be reduced by such general influences as malnutrition, worry and overwork and whether there is any acquired immunity resulting from the previous infection with this particular organism. Most infectious diseases confer life long specific immunity. So that second attacks are very unusual. Furthermore, suitable injections of killed or weakened organisms or their toxins may stimulate this specific immunity without actively causing any clinical illness: this fact is the basis of the immunization procedures which are so important in the prevention of diseases such as diptheria, tetanus, poliomyelitis and typhoid. Passive immunization means conferring temporary protection against a diseases by injecting serum which has been taken from someone with an active immunity and which therefore contains a high concentrated of specific antibodies.
Carriers:Some people who are themselves immune from a particular infectious diseases may nevertheless harbour the specific organisms and transmit them from time to time to susceptible persons, either by direct contact or by infecting food or water. This carrier state is particularly important in the spread of typhoid fever.
Routes of infection: The invading organism usually gains access to the patient either in inspired air “droplet infection” or in contaminated food or drink.
Incubation period: After gaining access to the tissues of a susceptible individual, the invading consolidate their position before the symptoms of the diseases appear. This interval is known as the different infectious diseases, but remains in the constant in each of them. The approximate length fever is as follows below:
Less than 7 days Diptheria, Scarlet fever, Measles
10 to 14 days Whooping cough, Small pox, Enteric fever
14 to 21 days Chicken pox, German measles, Mumps.
It is important to know the incubation period of the various specific fevers, since it is occasionally helpful in diagnosis if the date of exposure to infection is known and also because it enables one to forecast the possible appearance of the diseases in people who have been in contact with the small pox it may be advisable to isolate such contacts until it is known whether or not they have contracted the diseases: the duration of this quarantine is worked out by adding a few days to the known incubation period.
Carriers:Some people who are themselves immune from a particular infectious diseases may nevertheless harbour the specific organisms and transmit them from time to time to susceptible persons, either by direct contact or by infecting food or water. This carrier state is particularly important in the spread of typhoid fever.
Routes of infection: The invading organism usually gains access to the patient either in inspired air “droplet infection” or in contaminated food or drink.
Incubation period: After gaining access to the tissues of a susceptible individual, the invading consolidate their position before the symptoms of the diseases appear. This interval is known as the different infectious diseases, but remains in the constant in each of them. The approximate length fever is as follows below:
Less than 7 days Diptheria, Scarlet fever, Measles
10 to 14 days Whooping cough, Small pox, Enteric fever
14 to 21 days Chicken pox, German measles, Mumps.
It is important to know the incubation period of the various specific fevers, since it is occasionally helpful in diagnosis if the date of exposure to infection is known and also because it enables one to forecast the possible appearance of the diseases in people who have been in contact with the small pox it may be advisable to isolate such contacts until it is known whether or not they have contracted the diseases: the duration of this quarantine is worked out by adding a few days to the known incubation period.
Wednesday, January 26, 2011
Infectious diseases
Definition-Although the term “infectious diseases” might be logically be applied to any illness which results from invasion of the body by a microorganism, its use is customarily restricted to those diseases which spread by direct contact from person to person.At this time we should not be concerned with diseases like pneumonia or bacterial endocarditis which though due to infection can safely be nursed in general wards without special barrier precautions.
The occurance of illness in human is the result of the complex interactions between the responsible agent(exposure) the host and the environment( the epidemiological triad).
The virulence of an organism depends on its infectivity(ability to colonise) and its pathogenicity(ability to damage).
Diseases which are associated with a long incubation period are more difficult to control. The first lines of host defence against microorganisms are the physical and chemical barriers: these include the skin, mucosa, normal secretions, internal sphinchters and the resident endogenous flora.
Initially, microorganisms elicit a non-specific inflammatory host response: the recruitment of polymorphonuclear cells and the elaboration of cytokines are important components of this response. The macrophages of the reticuloendothelial system(splenic and alveolar macrophages, hepatic Kupffer cells, renal masangial cells and CNS microglia) play an important role in this response.
An organism specific immune response is also mounted by the host: activation of T and B lymphocytes culminates in immunoglobulin production and complement activation. Cell mediated immunity plays a ritical role in cambating intracellular bacteria.
Bacteremia refers to the presence of viable bacteria in blood. Infection refers to the presence of a microorganism in the body with a local inflammatory response. Sepsis refers to the presence of microorganism in the body with a systemic inflammatory response. Severe sepsis refers to sepsis associated with organ dysfunction, perfusion abnormalities or hypotension. Hypertension which is the main problem at present.
The occurance of illness in human is the result of the complex interactions between the responsible agent(exposure) the host and the environment( the epidemiological triad).
The virulence of an organism depends on its infectivity(ability to colonise) and its pathogenicity(ability to damage).
Diseases which are associated with a long incubation period are more difficult to control. The first lines of host defence against microorganisms are the physical and chemical barriers: these include the skin, mucosa, normal secretions, internal sphinchters and the resident endogenous flora.
Initially, microorganisms elicit a non-specific inflammatory host response: the recruitment of polymorphonuclear cells and the elaboration of cytokines are important components of this response. The macrophages of the reticuloendothelial system(splenic and alveolar macrophages, hepatic Kupffer cells, renal masangial cells and CNS microglia) play an important role in this response.
An organism specific immune response is also mounted by the host: activation of T and B lymphocytes culminates in immunoglobulin production and complement activation. Cell mediated immunity plays a ritical role in cambating intracellular bacteria.
Bacteremia refers to the presence of viable bacteria in blood. Infection refers to the presence of a microorganism in the body with a local inflammatory response. Sepsis refers to the presence of microorganism in the body with a systemic inflammatory response. Severe sepsis refers to sepsis associated with organ dysfunction, perfusion abnormalities or hypotension. Hypertension which is the main problem at present.
Tuesday, January 25, 2011
Conservation
Conservation is the management of the benefits of all life including human kind of the biosphere so that it may yield sustainable benefit to the present generation while maintaining its potential to meet needs and aspirations of the future generations.
Conservation of biological resources or natural resources has the following objectives:
To maintain the essential ecological process and life supporting system.
To preserve biological diversity.
To ensure that any utilization of species and ecosystems is sustainable.
Further we can say, fundamentally here are two reasons for conservations if can either benefit for human beings or for the benefit for the species.
Conservation involves the following four major proceses:
• Preservation of the endangered habitats or species.
• Management of ecosystem.
• Rreclamation of damaged habitats.
• Creation of new habitats.
Mainly there are two types of conservation.
• Ex-situ conservation
• In-situ conservation.
In situ conservation
In situ is the conservation of natural resources in their natural habitats or area of origin. The wildlife is conserved in protected areas systems such as national parks, wildlife reserve, conservation areas. In situ conaervation is the best method for the conservation in long run as the animals adapted to the natural condition since generations.
Ex situ conservation
Ex situ conservation is the conservation of natural resources outside their natural habitats or area of origin. An artificial but similarenvironment or habitats is maintained in place different than the original.Wildlife of threatened categories are kept in captivity which are artificially breeded. This method ensures that the species does not extinct. After the successful breeding in captivity, the offsprings can be reintroduced in natural environment. Examples botanical garden, zoo, zoological garden, aquarium, gene bank, etc.
Conservation of natural resources is the challenging task of the world. Conservation cannot be achieved in isolation. For the conservation of natural resources, these must be global alliance. The conservation education and ethnics should be imparted to all levels of society. The future of humanity depends upon the conservation of natural resources.
In practice following principles are to be adopted for the conservation of natural resources:
Reduce: Resources are limited and therefore we must not waste resources. Natural resources should be use only to meet basic needs. Reduction in consumption of resources will result in the reduction of wastage of resources and less production of waste materials. For e.g. creating awarness can reduce the use of petroleum products.
Reuse: Reuse involves using the same product again and again in its original form. For e.g. glass, beverage bottles, etc. can be collected, washed and refilled. Reuse reduces energy use and pollution.
Recycling: Items containing iron and aluminium account for 94% of all metals used. Damaged metals are collected, melted and converted into new products. Papers and glasses are also recycled. This process also saves energy and causes less pollution. Reuse or recycling process is called resources recovery.
Conservation of biological resources or natural resources has the following objectives:
To maintain the essential ecological process and life supporting system.
To preserve biological diversity.
To ensure that any utilization of species and ecosystems is sustainable.
Further we can say, fundamentally here are two reasons for conservations if can either benefit for human beings or for the benefit for the species.
Conservation involves the following four major proceses:
• Preservation of the endangered habitats or species.
• Management of ecosystem.
• Rreclamation of damaged habitats.
• Creation of new habitats.
Mainly there are two types of conservation.
• Ex-situ conservation
• In-situ conservation.
In situ conservation
In situ is the conservation of natural resources in their natural habitats or area of origin. The wildlife is conserved in protected areas systems such as national parks, wildlife reserve, conservation areas. In situ conaervation is the best method for the conservation in long run as the animals adapted to the natural condition since generations.
Ex situ conservation
Ex situ conservation is the conservation of natural resources outside their natural habitats or area of origin. An artificial but similarenvironment or habitats is maintained in place different than the original.Wildlife of threatened categories are kept in captivity which are artificially breeded. This method ensures that the species does not extinct. After the successful breeding in captivity, the offsprings can be reintroduced in natural environment. Examples botanical garden, zoo, zoological garden, aquarium, gene bank, etc.
Conservation of natural resources is the challenging task of the world. Conservation cannot be achieved in isolation. For the conservation of natural resources, these must be global alliance. The conservation education and ethnics should be imparted to all levels of society. The future of humanity depends upon the conservation of natural resources.
In practice following principles are to be adopted for the conservation of natural resources:
Reduce: Resources are limited and therefore we must not waste resources. Natural resources should be use only to meet basic needs. Reduction in consumption of resources will result in the reduction of wastage of resources and less production of waste materials. For e.g. creating awarness can reduce the use of petroleum products.
Reuse: Reuse involves using the same product again and again in its original form. For e.g. glass, beverage bottles, etc. can be collected, washed and refilled. Reuse reduces energy use and pollution.
Recycling: Items containing iron and aluminium account for 94% of all metals used. Damaged metals are collected, melted and converted into new products. Papers and glasses are also recycled. This process also saves energy and causes less pollution. Reuse or recycling process is called resources recovery.
Sunday, January 23, 2011
Variety in the volcano
Variety in the volcano
Based on the history of the activity done by Volcano
Active-These volcanoes are currently errupting or exhibiting unrest through earthquakes and other gas emissions.
Dormant-These volcanoes are inactive, but have not been so long enough to be declared extinct.
Extinct-These volcanoes have been inactive in all of therecorded history.
Based on the shape Volcanoes are
Volcanic cone-These are among the simplest volcanic formations. These are built up of ejected materials around a volcanic cones are differentiated into cinder cones, spatter cones, ash cones and tuff cones. Cinder cones(Scoria cones) are built almost entirely of loose volcanic fragments called cinders. Hot fluid lava clots are called spatter. When spewed spatter falls back to the earth the clots weld together and solidify, forming steep-sided spatter cones. Fallen ash forms ash cone, which becomes a”tuff cone” or “tuff ring” once the loose ash particles weld together.
Shield Volcano- Shield volcanoes are formed by easily flowing lava that has low viscosity. Their heights are typically about 1/20th of their widths. The lower slopes are gentle but the middle slopes become steeper and then flatten at the summit. Many of the largest volcanoes on Earth are shield volcanoes. The Mauna Loa(Hawaii) is the world’s largest shield volcano.
Strato volcano- This is a tall, conical volcano with gentle lower slopes that rises steeply near the summit. The summit usually has a small crater. Many of the most dangerous and explosive volcanoes are stratovolcanoes. For example; Mt. Fuji (Japan), Mt. Mayon(Phillipines) and Mt. Agua(Guatemala).
Volcanic Erruptions
An erruptions begins when pressure on a magma chamber forces magma up and out the volcano’s vents. Of course, sideways- directed volcanic explosions(lateral blasts) can shoot ejected material at very high speeds for quite a distance. When magma reaches the Earht’s surface, it is called Lava. Lava may flows as gentle streams called lava flows or it may erupt violently into the air along with the lava are called pyroclastic rocks. This type of eruptions depends somewhat on the amount of gases and silica in the magma. The amount of Silica determines the viscosity of the magma. Steam is what powers the explosion.
Based on the history of the activity done by Volcano
Active-These volcanoes are currently errupting or exhibiting unrest through earthquakes and other gas emissions.
Dormant-These volcanoes are inactive, but have not been so long enough to be declared extinct.
Extinct-These volcanoes have been inactive in all of therecorded history.
Based on the shape Volcanoes are
Volcanic cone-These are among the simplest volcanic formations. These are built up of ejected materials around a volcanic cones are differentiated into cinder cones, spatter cones, ash cones and tuff cones. Cinder cones(Scoria cones) are built almost entirely of loose volcanic fragments called cinders. Hot fluid lava clots are called spatter. When spewed spatter falls back to the earth the clots weld together and solidify, forming steep-sided spatter cones. Fallen ash forms ash cone, which becomes a”tuff cone” or “tuff ring” once the loose ash particles weld together.
Shield Volcano- Shield volcanoes are formed by easily flowing lava that has low viscosity. Their heights are typically about 1/20th of their widths. The lower slopes are gentle but the middle slopes become steeper and then flatten at the summit. Many of the largest volcanoes on Earth are shield volcanoes. The Mauna Loa(Hawaii) is the world’s largest shield volcano.
Strato volcano- This is a tall, conical volcano with gentle lower slopes that rises steeply near the summit. The summit usually has a small crater. Many of the most dangerous and explosive volcanoes are stratovolcanoes. For example; Mt. Fuji (Japan), Mt. Mayon(Phillipines) and Mt. Agua(Guatemala).
Volcanic Erruptions
An erruptions begins when pressure on a magma chamber forces magma up and out the volcano’s vents. Of course, sideways- directed volcanic explosions(lateral blasts) can shoot ejected material at very high speeds for quite a distance. When magma reaches the Earht’s surface, it is called Lava. Lava may flows as gentle streams called lava flows or it may erupt violently into the air along with the lava are called pyroclastic rocks. This type of eruptions depends somewhat on the amount of gases and silica in the magma. The amount of Silica determines the viscosity of the magma. Steam is what powers the explosion.
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