An Infant with Acute Brucellosis Presenting With Coombs-Positive Autoimmune Hemolytic Anemia: Is Breastfeeding Guilty for Transmission?

Introduction

B rucellosis is a bacterial zoonosis transmitted directly or indirectly to humans from infected animals (Al-Eissa et al. 1990). It constitutes a major health problem in many parts of the world, with predominance in central Asia and some developing countries (Corbel et al. 2005, Pappas et al. 2006). Turkey is an endemic region for brucellosis (Kaya 2006). A total of 189,226 cases of human brucellosis were reported during the period of 1980–2005, which is approximately 15,000 cases per year (Yumak and O'Callaghan 2012).

Humans are commonly infected through consumption of unpasteurized milk, cheese, or meat or through direct contact with infected animals (Summaries of Infectious Diseases 1997, Sari et al. 2008, Kose et al. 2011). Neonatal infection can be acquired transplacentally or during delivery. Rarely, human infection in adults can be transmitted after sexual intercourse, blood transfusion, and bone marrow transplantation. The infection can be transmitted transplacentally or during delivery to newborns and by breastfeeding to children during the first year of life (Al-Mafada et al. 1993, Carrera et al. 2006, Kose et al. 2011).

Human brucellosis can be observed at any age and in either sex. The disease may lead to misdiagnosis and treatment delays, further increasing the complication rates because it shows wide clinical polymorphisms that are similar to various multisystemic diseases. Brucellosis usually causes abortion and sterility in animals. It may lead to a variety of clinical presentations in humans, such as fever and septicemia and muscle and major joint pain.

Acute illness is generally characterized by insidious onset of fever, night sweats, arthralgias, myalgias, low back pain, and weight loss, as well as weakness, fatigue, malaise, headache, dizziness, depression, and anorexia (Young 1995, Gotuzzo 1999, Pappas et al. 2005). However chronic brucellosis refers to patients with clinical manifestations for more than 1 year after onset of the initial illness (Spink 1951, Young 1995). Chronic brucellosis is characterized by localized infection (generally spondylitis, osteomyelitis, tissue abscesses, or uveitis) and/or relapse in patients with objective evidence of infection (Spink 1951, Young 1995, Gotuzzo 1999).

Due to its wide spectrum of symptoms, the diagnosis of the disease depends on laboratory tests as well as clinical symptoms. Brucella-specific immunoglobulin (Ig) M and G demonstration, PCR, agglutination tests, and isolation of Brucella spp. from the blood, bone marrow, or other sterile body sites are the most important diagnostic tools (Mantur et al. 2008).

Hematologic abnormalities reported in brucellosis include anemia, leukopenia, thrombocytopenia, pancytopenia, bone marrow hypoplasia, and thrombotic microangiopathy. Immune destruction of erythrocytes resulting in Coombs-positive autoimmune hemolytic anemia (AIHA) is unusual for acute brucellosis (Young 1995, Sari et al. 2008, Bourantas et al. 2012).

Our aim in this report is to show that breastfeeding could be a route of transmission in infants with brucellosis and to show importance of this infection in the differential diagnosis of Coombs-positive AIHA. We also wanted to emphasize breastfeeding as a route of Brucella transmision in infants.

Case

A 5-month-old infant was admitted to our clinic with complaints of fever, vomiting, cough, diarrhea, pallor, and dark urine. Her mother reported that these complaints had begun 5 days before the admission. The infant was only breastfeeding and no weaning has been started by her mother. At admission, her temparature was 38.5°C. She had pallor, 1/6 systolic murmur, hepatomegaly, and crackles in auscultation of the lungs but no splenomegaly. The laboratory studies showed a hemoglobin level of 6.2 gr/dL, total leukocyte count of 7900/mm³, mean corpuscular volume of 75 fl, mean corpuscular hemoglobin of 26 pg, mean corpuscular hemoglobin concentration of 34.5 gr/dL, red cell distribution width of 14.3%, and a platelet count of 350,000/mm³. Blood smear showed 50% neutrophils, 38% lymphocytes, 10% monocytes, and 2% band forms, but no atypical cells. Platelets were abundant with clumps; red blood cells were normocytic and normochromic with anisocytosis, polychromasia, and spherocytosis. The reticulocyte prodution index was 2.7%, lactate dehydrogenase (LDH) was 756 IU/L, and haptoglobulin was <70. The direct Coombs test was strongly positive (4+) for IgG. Cold aglutinin was negative. Aspartate transaminase, alanine transaminase, and total and direct bilirubin were 163 IU/L, 306 IU/L, 3.5 mg/dL, and 0.3 mg/dL, respectively. Urine analysis showed dark color and a density of 1020; protein (−), bilirubin (−), hemoglobinuria (−), urobilinogen (+), and no white or red blood cells were found in the sediment. The coagulation profile was normal. Erythrocyte sedimentation rate was 52 mm/h, C-reactive protein was 6.8 gr/dL (normal, 0.33 mg/dL). Her chest X-ray revealed paracardiac infiltration. Glucose-6-phosphate dehydrogenase (G6PD) and hemoglobin electrophoresis were normal. Results of serology testing for common infectious causes of autoimmune hemolysis, such as Mycoplasma pneumoniae and Epstein–Barr virus, were negative. Laboratory tests for underlying autoimmune diseases were also performed, with negative results. Bone marrow examination was normal with no hemophagocytosis.

After erythrocyte transfusion, 2 mg/kg per day steroid for AIHA and clarithromycin for pneumonic infiltration were started. On the second day of admission, we learned that the mother had been on therapy for Brucella for 15 days. The mother reported that she had fever, weakness, and myalgia since the day 45th after delivery, and she was diagnosed with brucellosis 3 months due to a positive Rose–Bengal Plate test and standard tube agglutination test with a titer of 1/640. Her blood culture for Brucella taken during therapy was negative. The mother had a history of consumption of unpasteurized milk and cheese; however, the child was only breastfeeding. The infant had a positive Rose–Bengal Plate test (Metser Lab, Turkey) and positive standard tube agglutination test with a titer of (1/360. Metser Lab, Turkey). Her blood culture subsequently revealed B. melitensis. The microorganism in mother's milk was not examined. Because serology for mycoplasma was negative, the clarithromycin therapy was stopped. Trimetoprim-sulfamethoxasole with a dose of 12 mg/kg per day and rifampicin 15 mg/kg per day orally were started. Formula was started instead of mother's milk. On the 3rd day of treatment, the patient showed clinical improvement. Fever was normal after the 5th day of treatment. On the 14th day of treatment, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), total bilirubin, LDH, and reticulocytes were in normal range. A steroid was used for 21 days. Coombs was negative on the 18th day of the treatment. Brucella treatment was continued for 6 weeks. The patient had no problems at the 1-year follow-up after treatment.

Discussion

Human-to-human transmission of brucellosis is rare (Palanduz et al. 2000). Transplacental transmission during pregnancy was also reported. Such transmission may be through contact with urine or feces during delivery or through swallowing the mother's blood (Kose et al. 2011). Breast milk, as a potential source of infection, is easily overlooked (Palanduz et al. 2000). There are data supporting transmission through breast milk in the literature (Al-Mafada et al. 1993, Carrera et al. 2006, Kos et al. 2011). In Turkey, in 2000, Palanduz et al. reported that the disease was transmitted from mother with a diagnosis of Brucella infection to a 3-month-old baby via breast milk (Palanduz et al. 2000). Al-Eissa et al. (1993) also reported a case with brucellosis transmitted via breast milk during neonatal period in Saudi Arabia. In Turkey, in 2011, Kose et al. (2011) reported a preterm infant with brucellosis infected via breast milk.

In Brucella infection, the active microorganism leads to clinical findings after 2–4 weeks (between 6 days and 3 months) of the incubation period Kose et al. 2011). In our case, the mother had complaints that started on postpartum day 45, and 3 months after this time she had the diagnosis. At admission to our hospital, the mother was on therapy with trimethoprim-sulfomethoxasole and rifampicin. Because the infant had the symptoms for 5 days before admission and the clinical picture was expected to occur earlier in intrauterine infection, intauterine brucellosis was not considered. It was considered that the mother who did not have clinical findings of Brucella infection during pregnancy acquired the infection as a result of consuming infected milk and dairy products after birth and that the 5-month-old baby who was fed only with breast milk was exposed to the disease agent via breastfeeding or by swallowing the blood seeping from unapparent minor cracks in the areola.

Brucellosis can mimic various multisystem diseases (Colmenero et al. 1996). Clinical findings of brucellosis are nonspecific for infants. Patients may also present with clinical findings, such as fever, arthralgia/arthritis, hepatosplenomegaly, or, more rarely, diarrhea, rash, night sweat, failure to gain weight, vomiting, and cough (Sari et al. 2008, Kose et al. 2011). It is particularly important to consider brucellosis in endemic areas where patients have had delayed diagnosis or misdiagnosis.

Some patients with brucellosis are hospitalized in hematology–oncology clinics because of the hematological abnormalities caused by the disease itself. There are several reports regarding the frequency and diversity of hematological abnormalities occurring in brucellosis (Crosby et al. 1984, Al-Eissa et al. 1993). Most common hematologic findings include anemia and leukopenia with relative lymphocytosis. Thrombocytopenia, pancytopenia, and hemolysis are less frequent (Sari et al. 2008a, Sari et al. 2008b). Al-Eissa et al. (1993) investigated the hematological changes during the active course of brucellosis infection in 110 children. They detected anemia in 44% of patients, of whom 4 had evidence of hemolysis, leukopenia occurred in 33%, thrombocytopenia in 5%, and pancytopenia in 14% of patients, of whom 1 developed disseminated intravascular coagulation. Clinically detectable bleeding occurred in 4.5% of patients. Incidence of pancytopenia with brucellosis varies from 3% to 21% in the published series (Crosby et al. 1984, Al-Eissa et al. 1993). The reasons for hemolysis in brucellosis may include microangiopatyhic hemolytic anemia, autoimmune hemolytic anemia, cold agglutinin disease, or the result of the long-term (chronic) disease or G6PD deficiency. Coombs-positive autimmune hemolytic anemia is rare, and there are a few cases reported in the literature (Al-Eissa and al-Nasser 1993). Hemolytic anemia may be associated with a great number of viral and bacterial infections. Most commonly seen viral infections are Epstein–Barr virus (EBV), cytomegalovirus (CMV), hepatitis, herpes simplex, mumps, measles, varicella, influenza A, coxsackie virus B, and human immunodeficiency virus (HIV). Most commonly seen bacterial infections are streptococcal infections, typhoid fever, Escherichia coli septicemia, M. pneumoniae, listeriosis, and syphilis (Foerster 1993). In a French study of 265 children with AIHA, 37% were classified as primary, 53% had an underlying immunological disorder, including Evans' syndrome, and 10% were postinfectious (Aladjidi et al. 2011).

Generally specific infectious agents, like M. pneumoniae, Epstein–Barr virus, varicella, mumps, measles, and rubella are associated with IgM autoantibodies (Rosenfield et al. 1965). These antibodies have a specificity for the I/i polysaccharide antigen system on red blood cells, although reactivity with the P polysaccharide antigen has been reported (Horwitz et al. 1984). Destruction of erythrocytes sensitized with IgM antibodies is mediated by the complement system. Red blood cell destruction may be due to direct cytolysis or degradation of red blood cells bound to C3, principally on liver macrophages (Foerster 1993). However, in case of infectious mononucleosis, 0.1–3% of patients experience clinical hemolysis, but anti-i is found in 8–69% of patients after infection. The majority of patients with antibodies do not show symptoms (Rosenfield et al. 1965, Foerster 1993). Immunologic cross-reactivity can be accepted as a cause of erythrocyte antibodies after the observation of reactivity of anti-I red blood cell antibodies with Mycoplasma antigens (Costea et al. 1972). Acute bacterial infections can cause hemolytic anemia in a different way. The T antigen on the erythrocyte surface is considered a “cryptic” antigen and normally is not available for binding. Infection with bacteria carrying neuraminidase activity leads to removal of sialic acid and subsequent exposure of the T antigen. Many persons have naturally occurring cold-reactive IgM antibodies with anti-T specificity, allowing hemolysis to result in this condition (Bird and Stephenson 1973).

Although breastfeeding was the source of this infant's infection, there are several advantages of breastfeeding. Infants who were breastfed exclusively for 6 months experienced less gastrointestinal infection, among many other infectious conditions (Policy Statement 2012), and have better growth than infants who were breastfed for 4 months or less (Kramer and Kakuma 2012).

In our case, the patient had a negative work-up, including other infectious causes and autoimmune markers that could have potentially explained the etiology of the autoimmune hemolytic anemia. Therefore, Brucella infection may be the probable cause of the immune hemolytic anemia in this patient. Patients with AIHA usually show acute hemolysis leading to pallor, palpitation, dyspnea, or congestive heart failure. Because of the high mortality rate in AIHA patients showing severe hemolysis, early recognition and immediate treatment are imperative (Jefferies 1994, Pappas et al. 2006). In our case, as soon as Coombs-positive AIHA was diagnosed, 2 mg/kg per day steroid therapy was started. Furthermore, antibrucellosis treatment was administered for the treatment of underlying disease.

In conclusion, the differential diagnosis of Coombs-positive AIHA should include brucellosis, especially in patients living in endemic areas. Transmission of Brucella infection from an infected mother via breastfeeding is a rare but important mode of transmission. Therefore, clinicans dealing with Brucella-infected mothers should compare the pros and cons of breastfeeding and may encourage an alternative method of feeding during the active stage of the mothers' illness and return to the breastfeeding as soon as possible.