Nosocomial transmission of tuberculosis infection in pediatrics wards

Diversity and evolution of Mycobacterium tuberculosis: moving to whole-genome-based approaches

Genotyping of clinical Mycobacterium tuberculosis complex (MTBC) strains has become a standard tool for epidemiological tracing and for the investigation of the local and global strain population structure. Of special importance is the analysis of the expansion of multidrug (MDR) and extensively drug-resistant (XDR) strains. Classical genotyping and, more recently, whole-genome sequencing have revealed that the strains of the MTBC are more diverse than previously anticipated. Globally, several phylogenetic lineages can be distinguished whose geographical distribution is markedly variable. Strains of particular (sub)lineages, such as Beijing, seem to be more virulent and associated with enhanced resistance levels and fitness, likely fueling their spread in certain world regions. The upcoming generalization of whole-genome sequencing approaches will expectedly provide more comprehensive insights into the molecular and epidemiological mechanisms involved and lead to better diagnostic and therapeutic tools.

Transmission of tuberculosis within family-households

OBJECTIVE

The introduction of molecular typing methods in the 1990s to study the epidemiology of tuberculosis (TB) has significantly improved the possibilities of quantifying transmission of Mycobacterium tuberculosis in different human settings. The purpose of this study was to investigate transmission of TB in 35 family-households in Poland.

METHODS

Two PCR-based genotyping methods: spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR) typing were used.

RESULTS

Of 78 patients, 49 (63%), could be assigned to intra-household transmission on the basis of identical DNA fingerprints upon a combined typing approach. However, if a single spoligotype spacer or a single MIRU-VNTR locus variation was tolerated in the cluster definition, the intra-household transmission raised to 85% of all patients. For 12 patients in 6 households, the M. tuberculosis isolates were clearly distinct in either spoligotyping or VNTR typing or in both genotyping methods, suggesting that these patients were infected by the sources in the community.

CONCLUSIONS

This study is the first to provide the results of a molecular epidemiological investigation performed within family-households in Poland. It shows the household setting as an important reservoir of M. tuberculosis transmission, and thus argues in favor of routine and extensive screening of the family contacts of TB patients.

American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America: Controlling Tuberculosis in the United States

During 1993-2003, incidence of tuberculosis (TB) in the United States decreased 44% and is now occurring at a historic low level (14,874 cases in 2003). The Advisory Council for the Elimination of Tuberculosis has called for a renewed commitment to eliminating TB in the United States, and the Institute of Medicine has published a detailed plan for achieving that goal. In this statement, the American Thoracic Society (ATS), Centers for Disease Control and Prevention (CDC), and the Infectious Diseases Society of America (IDSA) propose recommendations to improve the control and prevention of TB in the United States and to progress toward its elimination. This statement is one in a series issued periodically by the sponsoring organizations to guide the diagnosis, treatment, control, and prevention of TB. This statement supersedes the previous statement by ATS and CDC, which was also supported by IDSA and the American Academy of Pediatrics (AAP). This statement was drafted, after an evidence-based review of the subject, by a panel of representatives of the three sponsoring organizations. AAP, the National Tuberculosis Controllers Association, and the Canadian Thoracic Society were also represented on the panel. This statement integrates recent scientific advances with current epidemiologic data, other recent guidelines from this series, and other sources into a coherent and practical approach to the control of TB in the United States. Although drafted to apply to TB-control activities in the United States, this statement might be of use in other countries in which persons with TB generally have access to medical and public health services and resources necessary to make a precise diagnosis of the disease; achieve curative medical treatment; and otherwise provide substantial science-based protection of the population against TB. This statement is aimed at all persons who advocate, plan, and work at controlling and preventing TB in the United States, including persons who formulate public health policy and make decisions about allocation of resources for disease control and health maintenance and directors and staff members of state, county, and local public health agencies throughout the United States charged with control of TB. The audience also includes the full range of medical practitioners, organizations, and institutions involved in the health care of persons in the United States who are at risk for TB.

Tuberculosis among adult visitors of children with suspected tuberculosis and employees at a children's hospital

OBJECTIVE

Few children with tuberculosis (TB) have communicable disease, and most do not require isolation within the hospital. However, parents or adult visitors with unrecognized pulmonary TB may be a threat to hospital staff and other patients. We prospectively evaluated adults accompanying children hospitalized for suspected TB at a children's hospital to determine the frequency of undiagnosed, potentially contagious disease.

METHODS

From 1992 to 1998, chest radiographs were obtained from adult caretakers accompanying 59 consecutive children admitted to Texas Children's Hospital with suspected TB. A child and his or her family were placed under Airborne Precautions only if the child or the accompanying adult exhibited characteristics of potentially contagious disease. Annual rates of tuberculin skin test conversion in hospital employees were obtained for the same period.

RESULTS

Of the 105 screened adults, 16 (15%) had previously undetected pulmonary TB. These adults were associated with 14 (24%) of the 59 children. In all instances in which the adult was the patient's parent, he or she was the source of infection to the child. Only 8 (13.5%) of the 59 children required isolation. Tuberculin skin test conversion from a negative to a positive reaction occurred in 127 employees (8 per 1,000 employee-years at risk). Only 4 of these 127 employees performed activities involving direct patient contact. None was in contact with families with a known potentially contagious adult or pediatric patient.

CONCLUSIONS

The risk of infection of healthcare workers from pediatric patients with primary TB appeared to be minimal, and most children with TB did not need isolation. Infection control efforts should be focused on accompanying adults and adult visitors.

Essentials of paediatric infection control

Young children readily transmit and acquire nosocomial infections. Children are also vulnerable to endogenous infections as a result of the breakdown of their normal defences by disease, invasive procedures or therapy. The increasing acuity of illness in hospitalized children and therapeutic advances have resulted in a patient population that is increasingly at higher risk for nosocomial infections. Antibiotic resistance has emerged as a problem in some paediatric hospitals, usually in intensive care and oncology units. Infection rates are the highest in neonatal and paediatric intensive care units (where bloodstream infections are the most frequent), and are usually associated with intravascular devices. On general paediatric wards, respiratory and gastrointestinal infections predominate, reflecting the occurrence in the community. The surveillance of nosocomial infections identifies priorities for infection control activities and permits evaluation of interventions.The prevention of transmission between patients and to personnel requires that certain measures be taken with all patients, and that additional precautions be taken with some infections, based on the route of transmission. The prevention of transmission from personnel involves ensuring that personnel are appropriately immunized and counselled about working with infections. The prevention of nosocomial infection also involves control of visitors, appropriate management of invasive procedures and devices, sterilization and disinfection of equipment, provision of a clean environment and adequate staffing. Severely immunocompromised children require extra protection, including ventilation systems that reduce the risk of exposure to filamentous fungi. Infection control in paediatrics is an evolving field that must adapt to changes in the paediatric patient population and in health care technology.

Observational study of the use of infection control interventions for Mycobacterium tuberculosis in pediatric facilities

INTRODUCTION

Hospital transmission of Mycobacterium tuberculosis (TB) is a problem in US facilities where adults are treated. However, specific guidelines for facilities in which pediatric patients are cared for have never been defined, nor has any study attempted to assess pediatric health care worker (HCW) compliance with TB infection control (IC) guidelines.

METHODS

An observational study was performed in two pediatric inpatient hospitals from May, 1996, to December, 1997. A trained observer tallied persons (i.e. professional HCWs, ancillary HCWs and non-HCWs) entering and leaving occupied TB isolation rooms and recorded adherence with IC practices (e.g. proper use of respirators, prompt door closures, door signage).

RESULTS

Thirty children with confirmed or suspected TB were admitted during the study period and observed for a total of 242 h during which 656 visits by professional (n = 391) and ancillary (n = 131) HCWs and by family members (n = 134) were recorded. During 30% of visits doors remained open an average of 10 min, and during 20% of visits no respiratory protection was worn. In all, visitors wore the correct respiratory protection appropriately only 55% of the time. HCWs were more likely to wear respiratory protection when caring for children with a positive acid-fast bacillus smear than family members, but professional staff were no more likely than ancillary staff to do so.

CONCLUSIONS

This is the first study to quantify compliance with IC practices for TB in pediatric hospitals. The majority of visitors entering TB isolation rooms occupied by children with confirmed or suspected TB complied with IC guidelines, but discrepancies were seen. Rather than relying on TB IC guidelines designed for adult facilities, guidelines specific for pediatric facilities that consider the local epidemiology of TB should be developed.

Evaluation of Mycobacterium tuberculosis transmission from a pediatrician and initial compliance to prophylaxis of contacts in an outpatient pediatric clinic

OBJECTIVE

The risk that latent infection will progress to active tuberculosis is greater in infants and children than for most other age groups. We set out to determine the rate of transmission of Mycobacterium tuberculosis to pediatric patients exposed to a pediatrician with smear-negative and culture-positive pulmonary tuberculosis. We also explored factors associated with compliance to prophylaxis.

METHODS

Clinic and hospital billing records were used to identify patients age 5 or less who were seen during the pediatrician's potential contagious period. Patient were notified by registered mail of their putative exposure and were offered a tuberculin skin test screening with 5 tuberculin units of purified protein derivative (Tubersol, Connaught) and chest radiography of children with a tuberculin skin test > or =5 mm.

RESULTS

A total of 456 patients were identified as exposed; 140 contacts never responded for evaluation and 93 letters were not delivered because of incorrect mailing addresses. Of the 223 who completed screening 1 (0,4%) had a initial skin test result of 8 mm. The remaining 222 contacts had repeated negative test results. The only positive child (15 months old) was born in Honduras and had received Calmette-Guerin bacillus at birth. No active tuberculosis cases were identified in the 456 contacts up to 2 years after exposure. Compliance with prophylaxis was associated with having two or less children in the household (odds ratio, 2.5; 95% confidence interval, 1.1 to 5.9).

CONCLUSION

We found no evidence of transmission of M. tuberculosis in an outpatient pediatric setting. Only 43% of exposed children completed screening, and 38% of those offered prophylaxis completed their initial 3 months of therapy.

Transmission of multidrug-resistant tuberculosis

AIM

To compare the Mycobacterium tuberculosis isolates of adult index cases with multidrug-resistant (MDR) tuberculosis to the isolates obtained from their child contacts.

PATIENTS AND METHODS

A 4-year prospective study in the Western Cape Province of South Africa. We evaluated 149 child contacts of 80 adult MDR pulmonary tuberculosis cases. This report includes those cases where a culture for M. tuberculosis was obtained from both the adult source case and the child contact. Isolates were compared by drug susceptibility pattern and restriction fragment length polymorphism analysis.

RESULTS

Six adult-child pairs with cultures for M. tuberculosis were identified. Two children had contact with more than one adult tuberculosis case. One child received previous isoniazid prophylaxis. Drug susceptibility pattern and restriction fragment length polymorphism analysis were identical for five adult-child pairs. One child, with no other known source case, had a strain different from that of the identified source case, but the MDR M. tuberculosis strain with which he was infected was prevalent in the community in which he resided. All children responded well to treatment.

CONCLUSION

This study confirms that most of the childhood contacts of adults with MDR tuberculosis are likely to be infected by these MDR source cases despite their exposure to other drug-susceptible adults with tuberculosis in some instances. Child contacts of adults with MDR tuberculosis should be treated according to the drug susceptibility patterns of the likely source cases' M. tuberculosis strains unless their own strain's susceptibility testing indicates otherwise. Contact tracing remains of fundamental importance in identifying children at risk.

Costs associated with tuberculosis control programs at hospitals caring for children

OBJECTIVE

No data are available on the costs of implementing infection control measures for the control of Mycobacterium tuberculosis (MTB) in pediatric settings. In this study we determined the cost of MTB control measures at three hospitals caring for children.

DESIGN

Infection control and tuberculosis (TB) coordinators obtained cost data retrospectively for the years 1994 to 1995 for tuberculin skin test programs, respiratory protection programs and the retrofit or new construction of environmental controls in pediatric settings.

SETTING

Two pediatric hospitals and one pediatric ward in a large tertiary care hospital.

RESULTS

Total expenditures for TB controls ranged from $15270 to $28158 for the 2-year study period. Engineering controls involved the largest capital outlay at two of three facilities. Average yearly tuberculin skin test costs ranged from $949 to $12504/hospital. Respiratory protection programs cost from $480 to $1680 during the 2-year study period.

CONCLUSIONS

Costs associated with implementing control measures varied slightly by hospital but were less than those incurred by hospitals caring for adults. These costs represent improvements made to upgrade selected aspects of hospital TB control programs, not the cost of an optimal TB control program. Optimal TB control programs in pediatric settings have yet to be described.

APIC and CDC survey of Mycobacterium tuberculosis isolation and control practices in hospitals caring for children. Part 1: Patient and family isolation policies and procedures. Association for Professionals in Infection and Epidemiology, Inc

BACKGROUND

The 1994 Centers for Disease Control and Prevention draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities did not exempt pediatric facilities from instituting controls to prevent nosocomial tuberculosis (TB) transmission. Many researchers contend that TB disease in children does not require such rigid controls. We surveyed acute-care pediatric facilities in the United States to determine adherence to patient and family isolation policies and procedures.

METHODS

The study included 4 mailings of a survey to infection control professionals at 284 US children's hospitals and adult acute-care hospitals with > 30 pediatric beds.

RESULTS

The overall response rate was 69%. Only 41% of respondents reported having a written TB policy specifically designed for pediatric patients. Whereas 98% of respondents isolated pediatric patients with confirmed pulmonary TB, only 69% reported isolation of patients with miliary TB, and 79% reported isolation of patients with positive gastric aspirates. TB isolation policies for adult visitors were in place at 69% of hospitals, and 50% of hospitals evaluated adults for TB as part of the child's TB treatment plan. A median of 3 contact investigations occurred at each of 47% of respondent hospitals in the preceding 5 years.

CONCLUSIONS

Isolation and infection control policies for children with pulmonary TB largely conformed to published guidelines but varied for children with nonpulmonary TB. Because the greatest risk of nosocomial TB transmission in pediatric facilities comes from adults with TB, a rapid TB screening process for parents and adult contacts accompanying affected children should be instituted at facilities caring for children.

Evaluation of transmission of Mycobacterium tuberculosis in a pediatric setting

OBJECTIVE

To determine the extent of transmission of Mycobacterium tuberculosis to pediatric patients exposed to a pediatrician with smear- and culture-positive pulmonary tuberculosis (TB).

METHODS

Clinic billing and hospital admission records were used to identify patients seen during the pediatrician's infectious period. Patients were notified of the potential exposure and were offered screening.

RESULTS

A total of 1416 pediatric patients were identified as exposed. Of the 606 who completed screening, 12 (2%) had a skin test result > or = 10 mm, 2 (0.3 had a result 5 to 9 mm, and 592 (98%) had a negative test result (0 to 4 mm). No active TB cases were identified. Of the 14 children with a skin test result > or = 5 mm, 7 were U.S.-born and had no other risk for a positive skin test. The remaining seven had either been exposed to another person with infections TB or were from countries with a high prevalence of TB.

CONCLUSION

We found evidence of limited transmission of Mycobacterium tuberculosis in the outpatient pediatric setting. Despite extensive resources dedication, only 43% of exposed children completed screening. In similar situations decision should balance the responsibility to protect children exposed to Mycobacterium tuberculosis with other public health priorities and available resources.

IS6110 fingerprinting of drug-resistant Mycobacterium tuberculosis strains isolated in Germany during 1995

The epidemiological relatedness of drug-resistant Mycobacterium tuberculosis strains isolated in Germany in 1995 was evaluated by the standardized IS6110 fingerprinting method. Altogether, 196 M. tuberculosis isolates from 167 patients were analyzed. A large degree of IS6110 polymorphism was found, ranging from 1 to 20 copies. Multiple isolates from one patient generally remained stable over a period of up to 1 year. However, one strain showed an additional fragment 7 months after the first isolate was obtained. Isolates from 55 patients (33%) showed identical fingerprint patterns or fingerprint patterns that differed only in one band, and thus they were clustered in 22 fingerprint groups. Specific transmission links could be established between members of four groups, e.g., transmission by family contacts. In one case, transmission of a multidrug-resistant strain to a patient initially infected with a drug-susceptible strain could be shown. Besides these fingerprint groups, 30 of the 167 isolates (approximately 18%) could be grouped in two fingerprint clusters with a similarity of at least 78%. Approximately 60% of the patients of these two clusters were known to be immigrants from the former Soviet Union, and one patient is still living in Belarus. In conclusion, our results indicate that (i) transmission of drug-resistant strains contributes substantially to the emergence of drug-resistant tuberculosis in Germany and (ii) drug-resistant M. tuberculosis strains were presumably carried over from the former Soviet Union to Germany by immigrants.

Molecular epidemiology of Mycobacterium tuberculosis strains isolated during a 3-year period (1993 to 1995) in Seville, Spain

The genetic polymorphism of Mycobacterium tuberculosis strains isolated in Seville, Spain, was studied by using computer-assisted analysis of the IS6110 fingerprint in order to determine the current situation and to evaluate the human-to-human transmission of this pathogen. One hundred seventy-six isolates from 175 patients among the 205 patients diagnosed with tuberculosis (TB) during a 3-year period (1993 to 1995) were cultured and analyzed. One hundred nine patients (62%) were infected with genetically different isolates, and 67 isolates (38%) were grouped into 19 clusters. These results demonstrate that the level of clustering of strains in Seville is intermediate between those in developed and developing countries. Epidemiological relatedness was shown for isolates from only 10 of these clusters. Active and high transmission rates exist in children and in human immunodeficiency virus (HIV)-infected adults, while in non-HIV-infected adults this transmission rate is moderate. Although transmission from children to adults is uncommon, the probability of transmission from HIV-infected patients to young adults not infected with HIV may be higher. On the basis of these observations, we predict a constant rise in the rate of TB transmission among HIV-infected patients and probably in young adult patients not infected with HIV if measures for the effective prevention of TB among the HIV-infected population are not implemented.