DM2 Pt2-3 Mycobacterial infections

Question 1

What type of bacteria are mycobacteria?

Answer 1

Mycobacteria are intracellular, acid-fast, slow-growing bacilliform bacteria resistant to environmental conditions.

Question 2

What syndromes can mycobacterial infections cause in cats?

Answer 2

Mycobacteria can cause tuberculosis, atypical or non-tuberculous mycobacteriosis, and leprosy in cats.

Question 3

How do cats become infected with Mycobacterium microti?

Answer 3

Cats become infected through direct contact with small rodents like voles and mice.

Question 4

How is Mycobacterium bovis transmitted to cats?

Answer 4

M. bovis is transmitted through ingestion of infected milk or contact with badgers or infected environments.

Question 5

What is the concern related to zoonotic transmission of Mycobacterium from cats?

Answer 5

A recent case in the South of England proved zoonotic transmission of M. bovis from a cat to humans.

Question 6

What are the main risks for cats contracting non-tuberculous mycobacteria (NTM)?

Answer 6

The main risk is wound contamination from environmental sources like soil, water, and decaying vegetation.

Question 7

How do non-tuberculous mycobacterial infections in cats usually present?

Answer 7

Infections are often subcutaneous and dermal, presenting as localized skin lesions.

Question 8

How do cats become infected with Mycobacterium lepraemurium (feline leprosy)?

Answer 8

Cats become infected through direct contact, rodent bites, or wound contamination from soil or plants.

Question 9

What is the usual presentation of feline leprosy?

Answer 9

Feline leprosy typically presents as skin nodules.

Question 10

How is tuberculosis in cats caused by Mycobacterium bovis or M. tuberculosis typically presented?

Answer 10

Tuberculosis in cats is a systemic disease with disseminated internal lesions, but it can also present as cutaneous nodules and ulceration.

Question 11

What type of disease does Mycobacterium microti cause in cats?

Answer 11

M. microti can cause localized or disseminated cutaneous disease, sometimes with systemic dissemination.

Question 12

What are some non-specific tests used to assess mycobacterial infection in cats?

Answer 12

Non-specific tests include serum biochemistry, haematology, and radiography for lung, abdominal, or bone involvement.

Question 13

What radiographic changes may be seen in cats with mycobacterial infection?

Answer 13

Changes can include tracheo-bronchial lymphadenopathy, lung infiltration, localised lung consolidation, pleural effusion, and hepato- or splenomegaly.

Question 14

Why is hypercalcaemia important in mycobacterial infection?

Answer 14

Hypercalcaemia has been observed in some cases and correlates with a poorer prognosis.

Question 15

Why is the tuberculin skin test unreliable in cats?

Answer 15

Cats do not react strongly to intradermal tuberculin, making skin testing unreliable for diagnosing tuberculosis.

Question 16

What is the role of Ziehl-Neelsen (ZN) staining in diagnosing mycobacterial infection?

Answer 16

ZN staining is used on aspirates or biopsy samples to detect acid-fast organisms like mycobacteria.

Question 17

Why are some ZN-positive samples negative in culture?

Answer 17

ZN-positive organisms often fail to culture positive, and even when they do, culture can take around two months.

Question 18

What is the best practice for handling biopsy material for suspected mycobacterial infections?

Answer 18

Biopsy samples should be divided into three parts: one for ZN staining, one for histopathology, and one frozen for future culture.

Question 19

Why should precautions be taken when handling biopsy material suspected of mycobacterial infection?

Answer 19

Until the organism is properly characterised, it should be considered a potential human pathogen, requiring precautions.

Question 20

What legal obligations exist in the UK regarding suspected Mycobacterium bovis in cats?

Answer 20

Veterinary surgeons must notify the Divisional Veterinary Manager if tuberculosis is suspected in a domestic cat.

Question 21

What is typically seen on histopathology of tissues infected with mycobacteria?

Answer 21

Granulomatous inflammation with foamy macrophages containing acid-fast bacilli is typically seen.

Question 22

What key factors should be considered before treating a cat with suspected mycobacterial infection?

Answer 22

Consider zoonotic risk, involvement of household members, the extent of the disease, and long-term treatment requirements.

Question 23

Why is treatment of feline tuberculosis often contentious?

Answer 23

Treatment is long-term, difficult, costly, and poses a zoonotic risk, especially in cases with generalised disease or respiratory involvement.

Question 24

What is the prognosis for cats with uncomplicated cutaneous mycobacterial disease?

Answer 24

Cats with uncomplicated cutaneous disease have the most favorable prognosis.

Question 25

Why is surgical excision of cutaneous lesions not always successful?

Answer 25

Surgical excision of small lesions may help, but larger lesions often result in wound dehiscence or recurrence of infection.

Question 26

Why is the use of fluoroquinolones alone not recommended for treating mycobacterial infections?

Answer 26

Fluoroquinolone monotherapy can promote drug resistance, making double or triple therapy a better option.

Question 27

What is a potential consequence of generating drug resistance in mycobacterial infections?

Answer 27

Drug resistance can endanger both the infected cat and human patients by reducing treatment effectiveness.

Question 28

How long must treatment for mycobacterial infections typically continue?

Answer 28

Treatment typically requires a combination of two or three antibiotics for several months.

Question 29

Why is owner compliance challenging in treating mycobacterial infections in cats?

Answer 29

Treatment is long, difficult to maintain, and incomplete treatment can lead to failure and antibiotic resistance.

Question 30

What zoonotic risks should be communicated to owners of cats with mycobacterial infections?

Answer 30

Owners, especially those immunocompromised, should be informed of the zoonotic risk associated with mycobacterial infections in cats.

Question 31

What can be a reason for euthanising cats with mycobacterial infections?

Answer 31

Due to the length, cost of treatment, and zoonotic risk, some infected cats may be euthanased.