Bacterial infections

Question 1

What is the definition of toxaemia?

Answer 1

circulation of bacterial toxins in the blood causing pathological and clinical manifestation

Question 2

What is the definition of bacteraemia?

Answer 2

transient (temporary) presence of small numbers of low virulent (weak) bacteria in the blood without toxaemia

Question 3

What is the pathogenesis of bacteraemia?

Answer 3

bacteria enter the blood from septic focus [tonsillits] or after tooth extraction

Question 4

What are the effects of bacteraemia?

Answer 4

• in most cases, bacteria are destroyed by immune mechanisms especially when the number is small
• in some cases, the bacteria may localize in tissues causing pathological lesion, e.g. Staphylococcal bacteraemia may cause osteomyelitis (on top of haematoma) and Streptococcal bacteraemia may cause subacute bacterial endocarditis (congenital heart disease) (on top of rough valve)

Question 5

What is the definition of septicaemia?

Answer 5

• circulating, multiplying large numbers of virulent bacteria and their toxins in the blood
• the condition is highly fatal

Question 6

What are the sources of septicaemia?

Answer 6

infected pin prick (syringe), septic wounds, acute osteomyelitis. Bacteria invade the blood with low body resistance

Question 7

What is the definition of pyaemia?

Answer 7

• circulation of septic emboli in the blood and their arrest in different organs causing multiple small (pyaemic) abscesses
• the condition is highly fatal

Question 8

What is th pathogenesis of pyaemia?

Answer 8

• when inflammation extends from an inflamed area to vein wall it causes septic thrombo-phlebitis
• proteolytic enzymes cause break down of infected thrombus into small septic emboli, that circulate in the blood and get arrested in small vessels to form pyaemic abscesses

Question 9

What is the definition of actinomycosis?

Answer 9

• infective granuloma caused by Actinomyces Israel
• it is an anaerobic gram-positive bacteria
• the organism is a saprophyte in the mouth, carious teeth and intestine
• infection can be endogenous when the body immunity is lowered

Question 10

What is the gross pathological features of actinomycosis?

Answer 10

multiple inter-communicating abscesses opening to the surface by multiple openings discharging pus and yellow bacterial colonies (known as sulphur granules)

Question 11

What are the zones of each abscess in actinomycosis?

Answer 11

• central zone of pus containing rounded or oval bacterial colonies formed of thin filaments surrounded by club-like swellings
• mid zone of inflammatory cells including polymorphs, pus cells, lymphocytes, plasma cells, macrophages and giant cells
• outer zone of fibrosis

Question 12

What are the types of actinomycosis?

Answer 12

• cervicofacial actinomycosis (60%)
• intestinal actinomycosis (20%)
• pulmonary actinomycosis (15%)
• skin actinomycosis (5%)

Question 13

What happensin cervicofacial actinomycosis?

Answer 13

• affects the angle of mandible and adjacent parts of neck and face
• micro-organism enter through buccal mucosa after minor trauma
• blood spread, no lymphatic spread due to large size of filaments

Question 14

What happens in intestinal actinomycosis?

Answer 14

starts in the coecum, appendix and terminal ileum and extends to the abdominal wall where it opens by multiple fistulae

Question 15

What happens in pulmonary actinomycosis?

Answer 15

lesion starts usually in the base of the lung and spreads to chest wall where it opens by multiple sinuses

Question 16

What is the definition of mycetoma pedis?

Answer 16

chronic infective suppurative granuloma which affects mainly the foot. It is common in Madura in India and is called Madura foot

Question 17

What is the cause of mycetoma pedis?

Answer 17

saprophyte called Nocardia. Infection occurs through skin wound in bare-footed individuals

Question 18

What is the gross picture of mycetoma pedis?

Answer 18

• the foot is swollen, indurated and shows multiple intercommunicating abscesses opening to the surface by multiple openings discharging pus & yellow, red or black fungus colonies
• characteristically bone destruction is not accompanied by new bone formation

Question 19

What is the micro of mycetoma pedis?

Answer 19

• each abscess is formed of three zones
• central zone of pus
• mid zone of inflammatory cells
• outer zone of fibrosis

Question 20

What is the definition of candidiasis?

Answer 20

infection by fungus candida albicans

Question 21

What is the mode of infection of candidiasis?

Answer 21

• fungus is found in the mouth, intestine and vagina
• of healthy persons
• infection occurs when the body resistance is lowered as in debilitating diseases and with abuse of antibiotics

Question 22

What is the pathology of candidiasis?

Answer 22

• mucous membrane: hyperaemic and show small white patches (fungal filaments and necrotic debris) and in the mouth it is called thrush
• skin: interdigital moniliasis and paronychia
• viscera: yellow nodules in the lungs

Question 23

WHat is another name for candidiasis?

Answer 23

moniliasis