Summary notes – bubo aspirate PDF

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Summary notes – bubo aspirate

The bubo aspirate is injected subcutaneously into the animal, death of the animal occurs within 2-5 days. Postmortem of the dead animal shows edema and necrosis at congested and shows grayish white patches. Sputum collected from suspected cases of pneumonic plague is inoculated by applying them over the shaven skin or to the nasal mucosa of guinea pig. The bacteria present in the specimen penetrates the skin through minute abrasions. Bacilli are demonstrated in the sputum and in the blood from the heart of guinea pig which dies 2-3 days after inoculation.

Y. pestis is aerobic and facultatively anerobic. It grows at a temperature range of 2-45 °C with an optimum temperature of 27°C. The bacteria grows at a wide range of pH (5-9.6 with an optimum pH of 7.2). Y. pestis is a slow grower but it does not require any special growth media. For selective isolation of Y. pestis from sputum and bubo aspirates containing numerous other bacteria, Blood agar with sodium azide is used. On Nutrient Agar, colonies are small delicate, transparent that becomes opaque on prolonged incubation. On Blood Agar, colonies are dark brown due to absorption of the hemin pigment- non hemolytic colonies. On MacConkey Agar, colonies are non-lactose fermenters, growing best at 22-28° C. But colonies tend to auto-lyse after 2-3 days. On liquid media: Y. pestis produces a fluorescent growth with little or no turbidity. Granular deposit occurs at the bottom and along the sides of the tube. On prolonged incubation, a delicate pellicle may form at the surface Y. pestis produces a characteristics growth when grown in a flask of broth with oil or ghee floated on the top (ghee broth). The growth in the medium appears to hang down into the broth from the surface resembling stalactites (stalactite growth).

Killed vaccine is widely used for active immunization. It is a whole bacterial culture antigen of a virulent strain of plague bacillus.

A virulent strain of the plague bacillus is grown in Casein hydrolysate broth for 2-4 weeks at 32° C and killed by 0.05% formaldehyde and preserved with phenyl mercuric nitrate. The vaccine is given subcutaneously, 2 doses at an interval of 2-3 months followed by a third six month later. This killed vaccine have some protection against bubonic plague but not against pneumonic plague. Also, the protection does not last for more than 6 months.

Different animal species have been identified as hosts such as domestic cats and dogs, squirrels, camels and sheep. A sylvatic stage occurs when humans are infected from these wild animals.

Urban plague is maintained in rat population and is transmitted among rats or between rats and humans by infected rat fleas. Domestic rat is the important reservoir of urban plague from which the infection spreads to human beings. The rat flea is the usual vector. 30 different flea species have been identified as vectors, the most important being Y. cheopis, X. astia and Ceratophyllus fasciatus. X. cheopis is the predominant one.

Human infection may occur during handling of dead carcasses of infected wild animals and through the ingestion of meat of infected animals. Human infection from inhalation of respiratory droplets from infected cats has also been documented.

Cytomegalovirus (CMV) is a genus of viruses belonging to the order Herpesvirales, in the family Herpesviridae. CMV is the largest member of the human herpes virus family.Its natural host is human and monkeys. There is little genetic homology between human CMV and CMV of other species. Cytomegalovirus is a common virus infecting people of all ages rarely causing any clear illness. Out of 150 children, 1 is born with congenital cytomegalovirus infection. 80% of adults get infected by CMV before 40 years of age.

The envelope contains lipoproteins and at least 33 structural proteins, some of which are glycosylated.

The glycoprotein determine the strain of CMV, are used for cellular entry of the virus, and are the targets of virus-neutralizing antibody. CMV has genome of 236 kbp and more than 200 open reading frames (ORFs) encoding more than 80 viral proteins, including glycoproteins, phosphor-proteins and other transcription/replication proteins Genome analysis has indicated that mammalian CMV have co-speciated with their respective hosts over the last 80 million years. This prolonged period of co-evolution has resulted in a high level of coadaptation between the virus and its host

This phase begins with the immediate early transcription of the IE (alpha) genes during the first 4 hours after viral entry. This immediate early transcription event is dependent only on cellular factors and does not require de novo viral protein synthesis. Non-structural proteins appear in the nucleus within 4 hours after infection. These proteins are essential for the regulation of the expression of the early- and late-phase genes, and also for manipulating various cellular processes....