A. Cat-Scratch Disease

 Cat-scratch disease is usually a benign, self-limited illness manifested by fever and lymphadenopathy that develop 1–3 weeks after contact with a cat (usually a scratch, lick, bite, or perhaps a flea bite). A primary skin lesion (papule or pustule) develops at the site. The patient usually appears well but may have low-grade fever and occasionally headache, malaise, and sore throat. The regional lymph nodes (axillary, epitrochlear, or cervical most commonly) are markedly enlarged and sometimes tender, and they may not subside for several weeks or even months. They may suppurate and discharge pus. Atypical cases (5–10%) may be characterized by preauricular lymphadenopathy and conjunctivitis (Parin aud’s oculoglandular syndrome). More serious systemic features, such as meningitis, encephalopathy, bone lesions, and retinitis, have been described. More than 22,000 cases a year are thought to occur in the United States.

The diagnosis of cat-scratch disease is based on (1) a suggestive history and physical findings; (2) aspiration of pus from lymph nodes that contain no bacteria culturable by routine methods; and (3) characteristic histopathologic findings with granulomatous lesions, which may include bacteria seen on silver-impregnated stains. A positive skin test result has also been included as a criterion, but is of historical interest only. A titer of 1:64 or greater in a single serum in the indirect fluorescent antibody (IFA) test strongly supports the diagnosis, but development of a diagnostic titer may be delayed or may not occur in immunocompromised patients. Enzyme immunoassays are available but may be less sensitive than IFA.

Cat-scratch disease is caused by B. henselae, a small, pleomorphic, Gram-negative rod present mainly in the walls of capillaries near follicular hyperplasia or within microabscesses. The organisms are seen best in tissue sections stained with Warthin-Starry silver impregnation stain; they may also be detected by immunofluorescent stains. Culture of B. henselae is generally not recommended for this relatively benign disease.

The reservoir for B. henselae is domestic cats, and one-third of cats or more (and possibly their fleas) may be infected. Contact with infected cats through skin lesions is thought to transmit the infection.

Cat-scratch disease occurs commonly in immunocompetent people and is usually self-limited. Treatment is mainly supportive: reassurance; hot, moist soaks; and analgesics. Aspiration of pus or surgical removal of an excessively large lymph node may ameliorate symptoms. While anecdotal reports demonstrate that tetracycline, azithromycin, trimethoprim–sulfamethoxazole, rifampin, gentamicin, or fluoroquinolone therapy may be helpful, more recent analyses do not support treatment with antibiotics.

B. Bacillary Angiomatosis

 Bacillary angiomatosis is a disease predominantly of immunosuppressed individuals, particularly individuals with AIDS. Rare cases occur in immunocompetent persons. Bacillary angiomatosis is characterized histopathologically as circum scribed lesions with lobular capillary proliferation and round, open vessels with cuboidal endothelial cells protruding into the vascular lumen. A prominent finding is epithelioid histiocytes surrounded by a loose fibromyxoid matrix. The pleomorphic bacilli can be seen in the subendothelial tissue when stained with the Warthin-Starry silver impregnation stain. The lesions may be infiltrated by polymorphonuclear leukocytes.

In its common form, bacillary angiomatosis presents as an enlarging red (cranberry-like) papule, often with surrounding scale and erythema. The lesions enlarge and may become several centimeters in diameter and ulcerate. There may be single or many lesions. The clinical appearance is often similar to that of Kaposi sarcoma in AIDS patients, but the two diseases are different histologically. Bacillary angiomatosis occurs in virtually every organ. Involvement of the liver (and spleen) is characterized by a proliferation of cystic blood-filled spaces surrounded by a fibromyxoid matrix containing the bacteria; this form of the disease is called peliosis hepatis and is usually accompanied by fever, weight loss, and abdominal pain. A bacteremic form of infection with the nonspecific signs of malaise, fever, and weight loss also occurs.

The diagnosis is confirmed by the characteristic histopathologic findings and demonstration of the pleomorphic bacilli on silver-stained sections. B. henselae and B. quintana can be isolated by direct culture of biopsies of involved tissue carefully obtained so that no contaminating skin bacteria are present. The biopsy specimens are homogenized in supplemented tissue culture medium and inoculated onto fresh chocolate agar and heart infusion agar with 5% rabbit blood. Cultures of blood obtained by the lysis centrifugation method can be inoculated onto the same media. The cultures should be incubated in 5% CO2 at 36°C for a minimum of 3 weeks. Specimens can also be cultured on eukaryotic tissue culture monolayers. Biochemically, B. henselae and B. quintana are relatively inert, including negative catalase and oxidase reactions and negative carbohydrate utilization tests. Enzyme activity can be seen with amino acid substrates by methods to test for preformed enzymes. Definitive identification is obtained by sequencing all or part of the 16S ribosomal RNA gene amplified by the PCR. Because of the difficulty in recovering Bartonella species from clinical material and the insensitivity to date of molecular methods, serologic testing is still considered by many to be the best option. IFA tests are the most frequently used.

Bacillary angiomatosis is treated with oral erythromycin (drug of first choice) or doxycycline (plus gentamicin for very ill patients) for a minimum of 2 months. The often rapid response of skin lesions to erythromycin is believed to be due to its anti-inflammatory and anti-angiogenic effects. Relapses are common but can be treated by the same initial drug regimen.

C. Trench Fever

 Trench fever (also known as quintan fever) is characterized by sudden onset of fever accompanied by headache, malaise, restlessness, and shin pain. Symptoms coincide with release of B. quintana in blood every 3–5 days with each episode lasting 5 days. A prominent affliction seen during World War I, B. quintana is now more frequently seen as a cause of culture negative endocarditis and bacteremia in homeless individuals.

The reservoir for B. henselae usually is the domestic cat, and patients with this organism as the etiology of bacillary angiomatosis often have contact with cats or histories of cat flea bites. The only known reservoirs for B. quintana are humans and the body louse.

اخر الاخبار

اخبار العتبة العباسية المقدسة

رئيس قسم الإعلام يبحث مع رئيس جامعة العميد آفاق التعاون في مجال تغطية الأنشطة العلمية والأكاديمية

قسم بين الحرمين يباشر أعمال صيانة الأرصفة في الساحة الوسطية والمناطق المحيطة بها وإدامتها

قسم الشؤون الفكرية ينظم حفل التكليف الشرعي للفتيات في بغداد تيمنًا بذكرى المولد النبوي الشريف

انطلاق النسخة التاسعة من البرنامج التطويري لمشروع (حاملة الرسالة الزينبية)

المزيد

الآخبار الصحية

هل يتنبأ الذكاء الاصطناعي بأمراضنا قبل حدوثها؟

وداعا للنظارات.. قطرة عين واحدة قد تغير كل شيء ؟

دراسة تكشف تأثير "تيك توك" وتطبيقات الفيديو على سلوك الأطفال

"أسرار خفية" في الشاي الأخضر.. تغير قواعد الصحة والوزن

المزيد

الآخبار التكنلوجية

أول قطار يعمل بالهيدروجين في أميركا يدخل الخدمة رسميًا

أجهزة أبل القادمة.. "حصن منيع" في عصر الهجمات الرقمية !

روسيا: تطلق قمرين اصطناعيين بواسطة الصاروخ سويوز 2.1

ميزة ثورية.. أبل تدخل عالم قياس ضغط الدم

المزيد

مواضيع ذات صلة

Bartonella bacilliformis

Legionella pneumophila and other Legionellae

Pathogenesis of Anaerobic Infections

Coxiella

Rickettsia, Orientia, Anaplasma, and Ehrlichia

Chlamydia pneumonia

Urinary Tract Infections

Actinomyces

Neisseria meningitidis

The Brucellae

Diagnostic Laboratory Tests of Bordetella pertussis

Chlamydia psittaci