Cat-scratch disease - Clinicals, Diagnosis, and Management

Infectious diseases

Clinicals - History

Fact Explanation
Fever Cat Scratch Disease (CSD) is caused by Bartonella henselae infection. One third of patients can present with low-grade fever. Prolonged fever can herald a hepatic or splenic abscess. Fever
Cat Scratch Disease (CSD) is caused by Bartonella henselae infection. One third of patients can present with low-grade fever. Prolonged fever can herald a hepatic or splenic abscess.
Presence of an erythematous papule Lymphadenopathy usually follows an erythematous papule at the inoculation site. These small papules can be most commonly observed on the scalp. Presence of an erythematous papule
Lymphadenopathy usually follows an erythematous papule at the inoculation site. These small papules can be most commonly observed on the scalp.
Tender lymphadenopathy Lymph Nodes that drain the inoculation site become enlarged and tender. Involved lymph nodes undergo the following changes: lymphoid hyperplasia, granulomatous changes ,microabscess formation, and suppuration. Tender lymphadenopathy
Lymph Nodes that drain the inoculation site become enlarged and tender. Involved lymph nodes undergo the following changes: lymphoid hyperplasia, granulomatous changes ,microabscess formation, and suppuration.
Temporary blindness This is due to Parinaud’s Oculoglandular syndrome (POS). This is an atypical presentation of the disease. Features are conjunctival, granuloma formation with preauricular lymphadenitis. Eye involvement is seen if patient's rub the eye after handling cats. Temporary blindness
This is due to Parinaud’s Oculoglandular syndrome (POS). This is an atypical presentation of the disease. Features are conjunctival, granuloma formation with preauricular lymphadenitis. Eye involvement is seen if patient's rub the eye after handling cats.
Periorbital swelling, tearing and Redlining of the eyes Also due to Parinaud’s oculoglandular syndrome (POS). Periorbital swelling, tearing and Redlining of the eyes
Also due to Parinaud’s oculoglandular syndrome (POS).
Abdominal pain If associated with prolonged fever, it can be due to hepatic and splenic abscesses or mesenteric infarction. Abdominal pain
If associated with prolonged fever, it can be due to hepatic and splenic abscesses or mesenteric infarction.
Acute onset of alteration of consciousness with seizures Encephalopathy is a complication of CSD. Acute onset of alteration of consciousness with seizures
Encephalopathy is a complication of CSD.
Difficulty in breathing and pleuritic chest pain This is due to pneumonia and pleural effusion that are complications of CSD. Dyspnoea can also be a feature of acute heart failure following endocarditis Difficulty in breathing and pleuritic chest pain
This is due to pneumonia and pleural effusion that are complications of CSD. Dyspnoea can also be a feature of acute heart failure following endocarditis
Persistent bone pain Can be accompanied by a discharging sinus. Occurs due to osteomyelitis which is a rare complication of the disease. Persistent bone pain
Can be accompanied by a discharging sinus. Occurs due to osteomyelitis which is a rare complication of the disease.
Back pain aggravated on movement Paravertebral abscess. Back pain aggravated on movement
Paravertebral abscess.
Solitary or multiple tender, red vascular papules or nodules This is due to cutaneous bacillary angiomatosis and it is seen in immunocompromised individuals. Systemic symptoms may also indicate extracutaneous manifestations or bacteremia. Solitary or multiple tender, red vascular papules or nodules
This is due to cutaneous bacillary angiomatosis and it is seen in immunocompromised individuals. Systemic symptoms may also indicate extracutaneous manifestations or bacteremia.
Sudden onset unilateral facial or limb weakness This occurs due to a stroke which can occur after embolisation from valvular vegetation. Sudden onset unilateral facial or limb weakness
This occurs due to a stroke which can occur after embolisation from valvular vegetation.
Acute onset oliguria, hypertension, lethargy and edema This is due to post- infectious glomerulonephritis with secondary renal failure. Acute onset oliguria, hypertension, lethargy and edema
This is due to post- infectious glomerulonephritis with secondary renal failure.
Cat scratch or bite in the recent past Cat scratch or a bite or any exposure to cat fleas should be elicited. The pathogenic bacteria is present in the cat's saliva and in its circulation. Cat scratch or bite in the recent past
Cat scratch or a bite or any exposure to cat fleas should be elicited. The pathogenic bacteria is present in the cat's saliva and in its circulation.
Living in a humid warm climate Cat flea infestations are higher in a warm humid climate. Living in a humid warm climate
Cat flea infestations are higher in a warm humid climate.

Clinicals - Examination

Fact Explanation
Febrile patient This is usually a low grade fever. Febrile patient
This is usually a low grade fever.
Presence of erythematous papules These small papules are commonly observed at the site of inoculation. Presence of erythematous papules
These small papules are commonly observed at the site of inoculation.
Tender lymphadenopathy Causes a unilateral lymphadenopathy and usually one or a few nodes are palpable. Common sites of lymphadenopathy are axillary, head and neck, inguinal regions. Tender lymphadenopathy
Causes a unilateral lymphadenopathy and usually one or a few nodes are palpable. Common sites of lymphadenopathy are axillary, head and neck, inguinal regions.
Periorbital swelling, tearing and redlining of eyes This is due to Parinaud’s oculoglandular syndrome (POS).This is a rare presentation, it is associated with conjunctivitis, granuloma formation with preauricular lymphadenitis. Periorbital swelling, tearing and redlining of eyes
This is due to Parinaud’s oculoglandular syndrome (POS).This is a rare presentation, it is associated with conjunctivitis, granuloma formation with preauricular lymphadenitis.
Hepatomegaly There can be a tender hepatomegaly following hepatic abscesses or due to hepatic congestion following bacteremia. Hepatomegaly
There can be a tender hepatomegaly following hepatic abscesses or due to hepatic congestion following bacteremia.
Splenomegaly Mild splenomegaly can be present if there is splenic abscess formation. Splenomegaly
Mild splenomegaly can be present if there is splenic abscess formation.
Dull percussion note on respiratory examination Due to a pleural effusion. Dull percussion note on respiratory examination
Due to a pleural effusion.
Coarse lung crackles and rhonchi Due to the presence of a pneumonic consolidation. Coarse lung crackles and rhonchi
Due to the presence of a pneumonic consolidation.
Bilateral fine end inspiratory crackles Indicates acute heart failure following bacterial endocarditis and valvular insufficiency. Bilateral fine end inspiratory crackles
Indicates acute heart failure following bacterial endocarditis and valvular insufficiency.
New onset cardiac murmurs Due to bacterial endocarditis. This commonly causes mitral or aortic insufficiency. New onset cardiac murmurs
Due to bacterial endocarditis. This commonly causes mitral or aortic insufficiency.
Confusion and low GCS CSD can cause encephalopathy. Confusion and low GCS
CSD can cause encephalopathy.
Cranial nerve palsies This is due to entrapment of cranial nerves within the cranium, due to meningeal inflammation. Cranial nerve palsies
This is due to entrapment of cranial nerves within the cranium, due to meningeal inflammation.
Neck stiffness If positive indicates meningitis, this occurs as passive stretching of the meninges causes spasm of the cervical musculature. Neck stiffness
If positive indicates meningitis, this occurs as passive stretching of the meninges causes spasm of the cervical musculature.
Limb weakness of paralysis Myelitis and ischemic stroke can follow cardiac embolization. Limb weakness of paralysis
Myelitis and ischemic stroke can follow cardiac embolization.
Disc edema and exudates of the macula This is due to neuroretinitis. Disc edema and exudates of the macula
This is due to neuroretinitis.
Bone tenderness, presence of discharging sinuses Osteomyelitis is a rare complication of CSD. , Bone tenderness, presence of discharging sinuses
Osteomyelitis is a rare complication of CSD. ,
Solitary or multiple tender, reddish, highly vascular papules or nodules with a variable cutaneous distribution This is due to cutaneous bacillary angiomatosis and it is seen most commonly in immunocompromised individuals. Solitary or multiple tender, reddish, highly vascular papules or nodules with a variable cutaneous distribution
This is due to cutaneous bacillary angiomatosis and it is seen most commonly in immunocompromised individuals.

Investigations - Diagnosis

Fact Explanation
Serology The antibodies produced against the pathogen can be tested for by performing indirect fluorescent assay or enzyme-linked immunosorbent assay. This is the best initial test. Serology
The antibodies produced against the pathogen can be tested for by performing indirect fluorescent assay or enzyme-linked immunosorbent assay. This is the best initial test.
Culture of Blood, lymph node aspirates, biopsy specimens of skin or other involved tissues. The Bartonella species is difficult to culture; there it is not routinely requested. Microscopic appearance of B. henselae is a curved, aerobic gram-negative bacillus which stains with silver. Culture of Blood, lymph node aspirates, biopsy specimens of skin or other involved tissues.
The Bartonella species is difficult to culture; there it is not routinely requested. Microscopic appearance of B. henselae is a curved, aerobic gram-negative bacillus which stains with silver.
Polymerase Chain Reaction (PCR) PCR can detect different Bartonella species. It has a high specificity but the sensitivity is lower than with serology. Polymerase Chain Reaction (PCR)
PCR can detect different Bartonella species. It has a high specificity but the sensitivity is lower than with serology.
Lymph node biopsy Lymph node biopsy is only needed in situations where lymph nodes don't involute and when diagnosis is uncertain. Specimens show lymphoid hyperplasia and stellate granulomas. Lymph node biopsy
Lymph node biopsy is only needed in situations where lymph nodes don't involute and when diagnosis is uncertain. Specimens show lymphoid hyperplasia and stellate granulomas.
Skin biopsy Bacillary angiomatosis causes cutaneous or subcutaneous lesions. Histopathologic
examination (by light microscopy) may
confirm the diagnosis. Characteristic lobular proliferation of vasculature is seen with hematoxylin and eosin stain.
Skin biopsy
Bacillary angiomatosis causes cutaneous or subcutaneous lesions. Histopathologic
examination (by light microscopy) may
confirm the diagnosis. Characteristic lobular proliferation of vasculature is seen with hematoxylin and eosin stain.

Investigations - Management

Fact Explanation
Ultrasound scan of the abdomen This is needed in systemic CSD with hepatosplenic involvement. Scattered hypoechoic lesions are seen on ultrasound. Ultrasound scan of the abdomen
This is needed in systemic CSD with hepatosplenic involvement. Scattered hypoechoic lesions are seen on ultrasound.
CT scan of the abdomen Indicated in systemic CSD with hepatosplenic involvement. Hypodense lesions (liver and/or spleen) are seen on CT. CT scan of the abdomen
Indicated in systemic CSD with hepatosplenic involvement. Hypodense lesions (liver and/or spleen) are seen on CT.
Chest X-ray Pulmonary involvement, with pneumonic features (consolidations) and/or pleural effusion, can be seen. Chest X-ray
Pulmonary involvement, with pneumonic features (consolidations) and/or pleural effusion, can be seen.
Cerebro Spinal Fluid (CSF) analysis Detection of B. henselae antibodies in the spinal fluid is suggestive of meningo-encephalitis. Cerebro Spinal Fluid (CSF) analysis
Detection of B. henselae antibodies in the spinal fluid is suggestive of meningo-encephalitis.
Bone X-ray Osteomyelitis can be identified with lytic lesions on x-ray. Bone X-ray
Osteomyelitis can be identified with lytic lesions on x-ray.
Echocardiography This is to diagnose bacterial endocarditis. Valvular vegetations will be seen. Echocardiography
This is to diagnose bacterial endocarditis. Valvular vegetations will be seen.

Management - Supportive

Fact Explanation
Avoid provoking with cats This is to prevent scratches. Cats saliva contains the pathogen and scratch can introduce the pathogen into the bloodstream. This is most important in immunocompromised individuals. Avoid provoking with cats
This is to prevent scratches. Cats saliva contains the pathogen and scratch can introduce the pathogen into the bloodstream. This is most important in immunocompromised individuals.
Wash hands after handling cats Washing clears the saliva of the cats that might contain the pathogenic bacteria. Wash hands after handling cats
Washing clears the saliva of the cats that might contain the pathogenic bacteria.
Treat cats for fleas Fipronil and other spot-on treatments can be used to treat the fleas who act as vectors of the disease. Treat cats for fleas
Fipronil and other spot-on treatments can be used to treat the fleas who act as vectors of the disease.
Keep pet cats indoors and away from stray cats. This helps to minimize transmission among the cat population. Keep pet cats indoors and away from stray cats.
This helps to minimize transmission among the cat population.

Management - Specific

Fact Explanation
Azithromycin Antibiotics are indicated only in moderately ill patients (example: those with chest infections). Otherwise CSD is a self limiting condition and no antibiotics are needed. Azithromycininhibits bacterial protein synthesis and is bacteriostatic. It has good gram negative cover and less effective against gram positives. It is given orally in this condition. Azithromycin
Antibiotics are indicated only in moderately ill patients (example: those with chest infections). Otherwise CSD is a self limiting condition and no antibiotics are needed. Azithromycininhibits bacterial protein synthesis and is bacteriostatic. It has good gram negative cover and less effective against gram positives. It is given orally in this condition.
Erythromycin or Doxycycline Erythromycin inhibits bacterial protein synthesis and is bacteriostatic.It has good gram negative cover but is less effective against gram positives. It is given orally in this condition.It is given orally in this condition. Doxycycline inhibits bacterial protein synthesis and is bacteriostatic. It has a broad spectrum action. It is given orally in this condition. This is used in managing Bartonella endocarditis. Erythromycin or Doxycycline
Erythromycin inhibits bacterial protein synthesis and is bacteriostatic.It has good gram negative cover but is less effective against gram positives. It is given orally in this condition.It is given orally in this condition. Doxycycline inhibits bacterial protein synthesis and is bacteriostatic. It has a broad spectrum action. It is given orally in this condition. This is used in managing Bartonella endocarditis.
Rifampin Rifampin is a bactericidal, broad spectrum antibiotic. It is given orally. It is an alternative for other antibiotics in CSD. Rifampin
Rifampin is a bactericidal, broad spectrum antibiotic. It is given orally. It is an alternative for other antibiotics in CSD.
Ciprofloxacin Ciprofloxacin is a bactericidal antibiotic with more gram negative cover.This is given orally in CSD. It is an alternative for other antibiotics in CSD. Ciprofloxacin
Ciprofloxacin is a bactericidal antibiotic with more gram negative cover.This is given orally in CSD. It is an alternative for other antibiotics in CSD.
Trimethoprim/sulfamethoxazole (Co-trimoxazole) Trimethoprim/sulfamethoxazole (Co-trimoxazole) is a synergistic combination that acts as a bacteriostatic agent. It has broad spectrum activity. This can be given orally or intravenously. This is an alternative to other antibiotics in CSD. Trimethoprim/sulfamethoxazole (Co-trimoxazole)
Trimethoprim/sulfamethoxazole (Co-trimoxazole) is a synergistic combination that acts as a bacteriostatic agent. It has broad spectrum activity. This can be given orally or intravenously. This is an alternative to other antibiotics in CSD.
Gentamicin Gentamicin can be an alternative to other drugs mentioned. Intramuscular or intravenous routes can be used. This can be used as an alternative to other drugs in CSD. Gentamicin
Gentamicin can be an alternative to other drugs mentioned. Intramuscular or intravenous routes can be used. This can be used as an alternative to other drugs in CSD.

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