Tuberculosis is an ancient disease with a high prevalence worldwide; however, congenital presentation is not frequent and is little reported in the literature. It is acquired in utero by transplacental passage through the umbilical vein, by aspiration and ingestion of contaminated amniotic fluid, or by direct contact with maternal genital lesions. Diagnosis is often challenging, and neonates, in particular, represent a vulnerable population at high risk of developing severe acute disseminated disease. They usually present with nonspecific clinical manifestations; hence, the epidemiological history is critical for diagnostic suspicion [1] .

In most previous case reports, the diagnosis of the neonate was not known until the onset of symptoms in the third week of life; however, due to the history of mycobacteremia in the mother in the 29th week of gestation and poor adherence to treatment, the patient was at high risk of vertical transmission; therefore, the diagnosis was made on the third day of life with evidence of Mycobacteria in the second gastric juice sample despite being asymptomatic, taking into account that the gold standard for the diagnosis of this pathology is the anatomopathological study of the placenta, however, unfortunately, the sample was not available. In Colombia, as in other parts of the world, there are very few reported cases [2] .

TB is one of the principal infectious diseases worldwide; it is caused by the microorganism Mycobacterium tuberculosis, which belongs to the Mycobacterium family. It is a gram-positive, slow-growing, non-motile, non-spore-forming, strictly aerobic, acid-alcohol-resistant bacteria. The transmission is usually by airborne particles and, to a lesser extent, by vertical transmission [3] - [5] .

Congenital tuberculosis is defined by the intrauterine or intrapartum acquisition of Mycobacterium tuberculosis. It is infrequent but largely undetected. Even though tuberculosis is a medium-incidence disease worldwide (130 cases/100,000 inhabitants), there is global concern about the disease during pregnancy, as it is not routinely screened.

In low-incidence countries, the estimated prevalence of TB in pregnant women reaches 10 to 20 cases per 100,000 individuals, which increases to 60 per 100,000 in high-incidence countries. The incidence of congenital TB remains unknown, with less than 400 published cases in the scientific literature [6] ; however, it is known that the fetal transmission rate ranges between 0 - 16%, being exceptional when the mother has received adequate treatment for pulmonary TB. Delay in diagnosis is the most significant contributor to mortality by congenital TB, which varies between 44 - 50%.

Intrauterine transmission occurs by hematogenous dissemination, usually from the rupture of a placental tubercle, and then transmitted to the fetus via the umbilical vein or from aspiration or ingestion of infected amniotic fluid or blood. As a result, the bacteria can seed into the liver or lungs and form multiple primary complexes [7] [8] .

On the other side, perinatal TB is acquired in the immediate postpartum period, in which microorganisms are transmitted to the neonate either by ingestion or inhalation of the infected droplets from the mother or by direct contact with the infected genital tract, injured skin, mucous membranes or with other infected people [9] .

The kidneys and liver are the main organs affected in congenital TB; however, the clinical manifestations are generally nonspecific and may vary according to the inoculum, involved site, and size of caseous lesions.

Some clinical findings reported in the literature include hepatomegaly with/without splenomegaly, respiratory distress, lymphadenopathy, fever, irritability, and lethargy ( Table 2 ). Our patient only presented respiratory distress, which could have been related to prematurity. It is essential to consider other differential diagnoses, such as transient tachypnea of the newborn, respiratory distress syndrome, meconium aspiration syndrome, pneumonia, sepsis, pneumothorax, persistent pulmonary hypertension of the newborn, and even delayed transition. However, the mother’s medical history was highly relevant, making it necessary to confirm or rule out congenital tuberculosis.

The clinical, social, and infectious profile of the mother should be considered. Beitzke criteria were classically described in 1935 and consequently reviewed by Cantwell in 1994, yet its usefulness is currently debated, considering that studies of the placenta are only sometimes available and that imaging findings may appear late [10] . Initial diagnostic evaluation of the infant includes a complete blood count, PCR, tuberculin test and/or interferon-gamma release assay, acid-fast smears, culture and molecular testing of respiratory specimens, blood cultures, and cerebrospinal fluid analysis. Organ involvement must be ruled out by cerebral and abdominal ultrasound, chest x-rays/tomography, and eye examination [3] [11] . Additionally, the anatomopathological and microbiological study of the placenta holds significant importance, with granulomas serving as a critical finding and constitute the starting point to guide the diagnosis [5] [9] [12] .

In previous case reports, the newborn’s diagnosis remained elusive until symptoms emerged in the second-third week of life. However, in our case, owing to the mother’s history of disseminated TB infection at week 29 of gestation and poor adherence to treatment, the patient was at high risk of vertical transmission. Therefore, despite the absence of symptoms, diagnostic tests, including microbiological studies, were ordered early, leading to a diagnosis on the second day of life. Unfortunately, obtaining the anatomopathological study of the placenta was impossible, which would have provided invaluable findings for the current case.

Treatment of congenital TB is similar to other forms of TB regardless of the transmission route [9] [13] Two-month intensive phase followed by ten months of the second phase since these patients have a high risk of presenting miliary TB and involvement of the central nervous system, is recommended. To date, there are no formal clinical trials focused on perinatal TB; however, current data has shown neonates have equal tolerance to regimens used in older patients [2] [14] .

Congenital TB continues to be a diagnostic challenge at present. We present the case of a patient with a diagnosis of congenital tuberculosis that could be made early thanks to the clinical suspicion due to maternal history and later by microbiological studies. This allowed the initiation of treatment before the presentation of clinical signs and symptoms and, therefore, a better outcome for the patient. The importance of keeping the diagnostic suspicion present is therefore emphasized, especially in tuberculosis-endemic countries, where this pathology should remain on the list of differential diagnoses in neonates with nonspecific clinical manifestations with no response to the usual treatment, especially if they have a suggestive maternal clinical history.