Suspected transmission of tuberculosis in a maternity ward from a smear-positive nurse: preliminary results of clinical evaluations and testing of neonates potentially exposed, Rome, Italy, 1 January to 28 July 2011

Risk of tuberculosis transmission by healthcare workers to children - a comprehensive review

Background

Children <15 years are at elevated risk of becoming infected with M. tuberculosis complex (Mtbc).

Objective

To assess the magnitude of Mtbc transmission by healthcare workers (HCW) to children.

Methods

Medline, Google Scholar and Cochrane library were searched to select primary studies in which HCW was the presumed index case and exposed infants and children aged below 15 years were screened for latent TB infection (LTBI).

Results

Of 4,702 abstracts, 19 original case reports covering one HCW each as presumed source case of Mtbc transmission to children, were identified. In sum, 11,511 children, of those 5,881 infants (51.1%), mostly in newborn nurseries, were considered contact persons and underwent tuberculin skin (TST) or Interferon gamma release assay (IGRA) testing. Test positivity was reported in 492/11,511 children (4.3%) coming from 14 studies. When test results considered falsely positive were excluded, the number of latently infected children decreased to 365/10,171 (3.6%). In all studies, the presumed duration of infectivity of the source case was, but the actual intensity and duration of exposure were not, decisive for the initiation of contact investigations. In only two of the studies, the contact time of the children towards the corresponding source case was estimated.

Conclusions

The results of our review suggest that the risk of Mtbc transmission from HCW to children in healthcare setting is considerably lower than reported in household settings. However, as the preselection of pediatric contacts appeared in most cases to be vague, the data found in the literature probably underestimates the actual risk.

High rate of transmission in a pulmonary tuberculosis outbreak in a primary school, north-eastern Italy, 2019

Italy is a low-incidence country for tuberculosis (TB). We describe a TB outbreak in a primary school in north-eastern Italy, involving 10 cases of active pulmonary disease and 42 cases of latent infection. The index case was detected in March 2019, while the primary case, an Italian-born schoolteacher, was likely infectious since January 2018. Administration of a pre-employment health questionnaire to school staff with sustained contact with children should be considered in low-incidence countries.

Risk Factors for Indeterminate Interferon-Gamma Release Assay for the Diagnosis of Tuberculosis in Children-A Systematic Review and Meta-Analysis

Background: Interferon-gamma release assays (IGRA) are well-established immunodiagnostic tests for tuberculosis (TB) in adults. In children these tests are associated with higher rates of false-negative and indeterminate results. Age is presumed to be one factor influencing cytokine release and therefore test performance. The aim of this study was to systematically review factors associated with indeterminate IGRA results in pediatric patients. Methods: Systematic literature review guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) searching PubMed, EMBASE, and Web of Science. Studies reporting results of at least one commercially available IGRA (QuantiFERON-TB, T-SPOT.TB) in pediatric patient groups were included. Random effects meta-analysis was used to assess proportions of indeterminate IGRA results. Heterogeneity was assessed using the I² value. Risk differences were calculated for studies comparing QuantiFERON-TB and T-SPOT.TB in the same study. Meta-regression was used to further explore the influence of study level variables on heterogeneity. Results: Of 1,293 articles screened, 133 studies were included in the final analysis. These assessed QuantiFERON-TB only in 77.4% (103/133), QuantiFERON-TB and T-SPOT.TB in 15.8% (21/133), and T-SPOT.TB only in 6.8% (9/133) resulting in 155 datasets including 107,418 participants. Overall 4% of IGRA results were indeterminate, and T-SPOT.TB (0.03, 95% CI 0.02-0.05) and QuantiFERON-TB assays (0.05, 95% CI 0.04-0.06) showed similar proportions of indeterminate results; pooled risk difference was-0.01 (95% CI -0.03 to 0.00). Significant differences with lower proportions of indeterminate assays with T-SPOT.TB compared to QuantiFERON-TB were only seen in subgroup analyses of studies performed in Africa and in non-HIV-infected immunocompromised patients. Meta-regression confirmed lower proportions of indeterminate results for T-SPOT.TB compared to QuantiFERON-TB only among studies that reported results from non-HIV-infected immunocompromised patients (p < 0.001). Conclusion: On average indeterminate IGRA results occur in 1 in 25 tests performed. Overall, there was no difference in the proportion of indeterminate results between both commercial assays. However, our findings suggest that in patients in Africa and/or patients with immunocompromising conditions other than HIV infection the T-SPOT.TB assay appears to produce fewer indeterminate results.

Performance of interferon-γ release assays in the diagnosis of confirmed active tuberculosis in immunocompetent children: a new systematic review and meta-analysis

Background

Tuberculosis (TB) is a global public health problem, causing morbidity and mortality in adults and children. The most reliable diagnostic tools currently available are the in vivo Tuberculin Skin Test (TST) and the ex vivo Interferon-γ release assays (IGRAs). Several clinical, radiological, and bacteriological features make the detection of active (overt disease) TB in children difficult. Although recently developed immunological assays such as QuantiFERON-TB Gold In-Tube (QFT-IT) and T-SPOT®.TB are commonly used to identify active TB in adults, different evidence is required for diagnosis in children. The purpose of this study was to reassess the sensitivity and specificity of IGRAs in detecting microbiologically confirmed active TB in immunocompetent children.

Methods

A systematic review and meta-analysis of studies reporting on the diagnostic accuracy of tests for TB in immunocompetent children aged 0–18 years, with confirmation by positive M. tuberculosis cultures, were undertaken. Electronic databases were searched up to September 2015 and study quality assessment was performed using QUADAS-2.

Results

Fifteen studies were included in our meta-analysis. Results showed that there were no significant differences in sensitivity between TST (88.2 %, 95 % confidence interval [CI] 79.4–94.2 %), QFT-IT (89.6 %, 95 % CI 79.7–95.7 %) and T SPOT (88.5 %, 95 % CI 80.4–94.1 %). However, both QFT-IT (95.4 %, 95 % CI 93.8–96.6 %) and T-SPOT (96.8 %, 95 % CI 94.2–98.5 %) have significantly higher specificity than TST (86.3 %, 95 % CI 83.9–88.6 %).

Conclusions

QFT-IT and T-SPOT have higher specificity than TST for detecting active TB cases in immunocompetent children.

Increasing the efficiency and yield of a tuberculosis contact investigation through electronic data systems matching

BACKGROUND

Electronic health data may improve the timeliness and accuracy of resource-intense contact investigations (CIs) in healthcare settings.

METHODS

In September 2013, we initiated a CI around a healthcare worker (HCW) with infectious tuberculosis (TB) who worked in a maternity ward. Two sources of electronic health data were employed: hospital-based electronic medical records (EMRs), to identify patients exposed to the HCW, and an electronic immunization registry, to obtain contact information for exposed infants and their providers at two points during follow-up.

RESULTS

Among 954 patients cared for in the maternity ward during the HCW's infectious period, the review of EMRs identified 285 patients (30%) who interacted with the HCW and were, thus, exposed to TB. Matching infants to the immunization registry offered new provider information for 52% and 30% of the infants in the first and second matches. Providers reported evaluation results for the majority of patients (66%).

CONCLUSION

Data matching improved the efficiency and yield of this CI, thereby demonstrating the usefulness of enhancing CIs with electronic health data.

Tuberculosis transmission from healthcare workers to patients and co-workers: a systematic literature review and meta-analysis

Healthcare workers (HCWs) are at risk of becoming infected with tuberculosis (TB), and potentially of being infectious themselves when they are ill. To assess the magnitude of healthcare-associated TB (HCA-TB) transmission from HCWs to patients and colleagues, we searched three electronic databases up to February 2014 to select primary studies on HCA-TB incidents in which a HCW was the index case and possibly exposed patients and co-workers were screened.We identified 34 studies out of 2,714 citations. In 29 individual investigations, active TB was diagnosed in 3/6,080 (0.05%) infants, 18/3,167 (0.57%) children, 1/3,600 (0.03%) adult patients and 0/2,407 HCWs. The quantitative analysis of 28 individual reports showed that combined proportions of active TB among exposed individuals were: 0.11% (95% CI 0.04-0.21) for infants, 0.38% (95% CI 0.01-1.60) for children, 0.09% (95% CI 0.02-0.22) for adults and 0.00% (95% CI 0.00-0.38) for HCWs. Combined proportions of individuals who acquired TB infection were: 0.57% (95% CI 7.28E-03 - 2.02) for infants, 0.9% (95% CI 0.40-1.60) for children, 4.32% (95% CI 1.43-8.67) for adults and 2.62% (95% CI 1.05-4.88) for HCWs. The risk of TB transmission from HCWs appears to be lower than that recorded in other settings or in the healthcare setting when the index case is not a HCW. To provide a firm evidence base for the screening strategies, more and better information is needed on the infectivity of the source cases, the actual exposure level of screened contacts, and the environmental characteristics of the healthcare setting.

[Spanish Society for Pediatric Infectious Diseases guidelines on tuberculosis in pregnant women and neonates (i): Epidemiology and diagnosis. Congenital tuberculosis]

Tuberculosis (TB) screening in pregnancy using tuberculin skin test (TST) is recommended in case of symptoms of TB disease, close contact with a patient with infectious TB, or high risk of developing active disease. The new interferon gamma release assay (IGRA) tests are recommended in BCG-vaccinated pregnant women with positive TST and no known risk factors for TB, and in those immunocompromised, with clinical suspicion of TB but negative TST. TB diagnosis is difficult due to the non-specific symptoms, the increased frequency of extrapulmonary disease, the delay in radiological examinations, and the high rate of tuberculin anergy. Neonatal TB can be acquired in utero (congenital TB), or through airborne transmission after delivery (postnatal TB). Congenital TB is extremely rare and does not cause fetal malformations. It may be evident at birth, although it usually presents after the second week of life. In newborns with no family history of TB, the disease should be considered in cases of miliary pneumonia, hepatosplenomegaly with focal lesions, or lymphocytic meningitis with hypoglycorrhachia, especially in those born to immigrants from high TB-burden countries. TST is usually negative, and IGRAs have lower sensitivity than in older children. However, the yield of acid-fast smear and culture is higher, mostly in congenital TB. Molecular diagnosis techniques enable early diagnosis and detection of drug resistance mutations. There is a substantial risk of disseminated disease and death.

Latent tuberculosis infection among a large cohort of medical students at a teaching hospital in Italy

The surveillance of latent tuberculosis infection (LTBI) in both healthcare workers and healthcare students is considered fundamental for tuberculosis (TB) prevention. The aim of the present study was to estimate LTBI prevalence and evaluate potential risk-factors associated with this condition in a large cohort of medical students in Italy. In a cross-sectional study, performed between March and December 2012, 1511 eligible subjects attending the Medical School of the University of Genoa, trained at the IRCCS San Martino-IST Teaching Hospital of Genoa, were actively called to undergo the tuberculin skin test (TST). All the TST positive cases were confirmed with an interferon-gamma release assay (IGRA). A standardized questionnaire was collected for multivariate risk analysis. A total of 1302 (86.2%) students underwent TST testing and completed the questionnaire. Eleven subjects (0.8%) resulted TST positive and LTBI diagnosis was confirmed in 2 (0.1%) cases. Professional exposure to active TB patients (OR 21.7, 95% CI 2.9-160.2; P value 0.003) and previous BCG immunization (OR 28.3, 95% CI 3.0-265.1; P value 0.003) are independently associated with TST positivity. Despite the low prevalence of LTBI among Italian medical students, an occupational risk of TB infection still exists in countries with low circulation of Mycobacterium tuberculosis.

Nosocomial Pulmonary Tuberculosis Contact Investigation in a Neonatal Intensive Care Unit

The diagnosis of smear-positive pulmonary tuberculosis in a medical officer working in a metropolitan Australian neonatal intensive care unit led to a contact investigation involving 125 neonates, 165 relatives, and 122 healthcare workers with varying degrees of exposure. There was no evidence of nosocomial tuberculosis transmission from the index case.

Subcutaneous emphysema as the first relevant clinical sign of complicated tubercular lymph node disease in a child

BACKGROUND

Children make up a significant proportion of the global tuberculosis (TB) caseload, and experience considerable TB-related morbidity and mortality. Unfortunately, it is not easy to diagnose TB in the first years of life because of the diversity of its clinical presentation and the non-specific nature of most of its symptoms.

CASE PRESENTATION

A 26-month-old male child was admitted to hospital because of the sudden onset of rapidly increasing swelling of the neck, face and upper trunk a few hours before. Upon admission, his temperature was 36.5°C, pulse rate 120/min, respiratory rate 36/min, and O2 saturation 97% in air. Palpation revealed subcutaneous emphysema (SE) over the swollen skin areas, and an examination of the respiratory system revealed crepitations in the left part of the chest without any significant suggestion of mediastinal shift. Chest radiography showed enlargement of the left lung hilum with pneumomediastinum and diffuse SE. Bronchoscopy was carried out because of the suspicion that the SE may have been due to the inhalation of a peanut. This excluded the presence of a foreign body but showed that the left main bronchus was partially obstructed with caseous material and showed significant signs of granulomatous inflammation on the wall. Contrast-enhanced computed tomography of the lungs confirmed the SE and pneumomediastinum, and revealed bilateral hilum lymph node disease with infiltration of the adjacent anatomical structure and a considerable breach in the left primary bronchus wall conditioning the passage of air in the mediastinum and subcutaneous tissue. As a tuberculin skin test and polymerase chain reaction for Mycobacterium tuberculosis on bronchial material and gastric aspirate were positive, a diagnosis of TB was made and oral anti-TB therapy was started, which led to the elimination of M. tuberculosis and a positive clinical outcome.

CONCLUSIONS

This is the first case in which SE was the first relevant clinical manifestation of TB and arose from infiltration of the bronchial wall secondary to caseous necrosis of the hilum lymph nodes. Physicians should be aware of the fact that SE is one of the possible initial signs and symptoms of early TB infection, and act accordingly.

Latent tuberculosis infection and associated risk factors among undergraduate healthcare students in Italy: a cross-sectional study

BACKGROUND

The screening of both healthcare workers and students attending teaching hospitals for latent tuberculosis infection (LTBI) is recommended in hospitals of many countries with a low-incidence of TB, including Italy, as a fundamental tool of tuberculosis (TB) control programs. The aim of the study was to estimate the prevalence of LTBI and evaluate the main risk-factors associated with this condition in a cohort of healthcare Italian students.

METHODS

In a cross-sectional study, performed between January and May 2012, 881 undergraduate students attending the Medical, Nursing, Pediatric Nursing and Midwifery Schools of the University of Genoa, trained at the IRCCS San Martino-IST Teaching Hospital of Genoa, were actively called to undergo the Tuberculin Skin Test (TST). All the TST positive cases were also tested with an Interferon-Gamma Release Assay (IGRA) to confirm the diagnosis of LTBI. A standardized questionnaire was collected for risk-assessment analysis.

RESULTS

Seven hundred and thirty-three (83.2%) subjects underwent TST testing. The prevalence of TST positives was 1.4%, and in 4 (0.5%) out of 10 TST positive cases LTBI diagnosis was confirmed by IGRA. No difference in the prevalence of subjects who tested positive to TST emerged between pre-clinical (n = 138) and clinical (n = 595) students. No statistically significant association between TST positivity and age, gender, and BCG vaccination was observed. The main independent variable associated with TST positivity was to be born in a country with a high TB incidence (i.e., ≥20 cases per 100,000 population) (adjusted OR 102.80, 95% CI 18.09-584.04, p < 0.001).

CONCLUSIONS

The prevalence of LTBI among healthcare students resulted very low. The only significant association between TST positivity and potential risk factors was to be born in high TB incidence areas. In countries with a low incidence of TB, the screening programs of healthcare students before clinical training can be useful for the early identification and treatment of the sporadic cases of LTBI.

High rate of Quantiferon positive and tuberculin negative tests in infants born at a large Italian university hospital in 2011: a cautionary hypothesis

In the summer of 2011, an outbreak of Mycobacterium tuberculosis infection was suspected, and widely publicized, to have occurred in a maternity ward of an Italian University Hospital based on a case of tuberculosis in a nurse and another case in a newborn. More than 1300 newborns in the Hospital were surveyed for the occurrence of latent TB by the use of interferon-gamma released assays, which was positive in 118 newborns, all negative at the tuberculin skin test. We present here several theoretical arguments and literature data suggesting caution in interpreting the interferon-gamma released assays positivity alone as indication of latent TB infection in newborns.