Nosocomial outbreak of tuberculosis in a renal transplant unit: application of a new technique for restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates

Bronchoscopy-related outbreaks and pseudo-outbreaks: A systematic review

OBJECTIVE

To identify and report the pathogens and sources of contamination associated with bronchoscopy-related outbreaks and pseudo-outbreaks.

DESIGN

Systematic review.

SETTING

Inpatient and outpatient outbreaks and pseudo-outbreaks after bronchoscopy.

METHODS

PubMed/Medline databases were searched according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, using the search terms "bronchoscopy," "outbreak," and "pseudo-outbreak" from inception until December 31, 2022. From eligible publications, data were extracted regarding the type of event, pathogen involved, and source of contamination. Pearson correlation was used to identify correlations between variables.

RESULTS

In total, 74 studies describing 23 outbreaks and 52 pseudo-outbreaks were included in this review. The major pathogens identified in these studies were Pseudomonas aeruginosa, Mycobacterium tuberculosis, nontuberculous mycobacteria (NTM), Klebsiella pneumoniae, Serratia marcescens, Stenotrophomonas maltophilia, Legionella pneumophila, and fungi. The primary sources of contamination were the use of contaminated water or contaminated topical anesthetics, dysfunction and contamination of bronchoscopes or automatic endoscope reprocessors, and inadequate disinfection of the bronchoscopes following procedures. Correlations were identified between primary bronchoscope defects and the identification of P. aeruginosa (r = 0.351; P = .002) and K. pneumoniae (r = 0.346; P = .002), and between the presence of a contaminated water source and NTM (r = 0.331; P = .004) or L. pneumophila (r = 0.280; P = .015).

CONCLUSIONS

Continued vigilance in bronchoscopy disinfection practices remains essential because outbreaks and pseudo-outbreaks continue to pose a significant risk to patient care, emphasizing the importance of stringent disinfection and quality control measures.

Mycobacterial infections in solid organ transplant recipients

Mycobacterium tuberculosis (MTB) infection in solid organ transplant (SOT) recipients remains a major challenge for physicians and surgeons. Active tuberculosis (TB) is associated with increased morbidity and mortality in SOT recipients. MTB usually develops after transplantation in a recipient with latent TB infection (LTBI) before transplantation and may also be transmitted from the donor or acquired from the community. Therefore, screening for LTBI in donors and recipients before transplantation is very important in preventing active disease after transplantation. This review article is based on recently published data, case series, and expert recommendations. We reviewed updated information about the epidemiology, diagnosis, and treatment of latent and active TB before and after transplantation. We also reviewed recent treatments for multidrug-resistant TB.

Tuberculosis among prisoners & health care workers

TB in prisons and among HCW is a major public health concern in countries having high burden of disease. Prompt detection of TB is must in prisons by screening on entry, passive screening, mass screening and contact screening via clinical evaluation, smear microscopy and chest X-rays. The new rapid diagnostic methods - True-NAAT, CBNAAT and Line Probe Assay are important tools in the diagnosis. Implementation of effective preventive measures at every steps in various settings, along with airborne infection control and protective measures for staff must be ensured.

Effectiveness of Latent TB Screening and Treatment in People Initiating Dialysis in British Columbia, Canada

Background:

People undergoing chronic dialysis are at an increased risk of active tuberculosis (TB). In 2012, the Canadian province of British Columbia began systematically screening people initiating dialysis for latent TB using interferon-gamma release assay (IGRA), and treating when appropriate.

Objective:

The objective of this study was to compare active TB rate in people who initiated dialysis and were screened using an IGRA compared with those not screened during the same period.

Design:

Retrospective cohort study.

Setting:

British Columbia (BC), a Canadian province of 5.0 million people with an active TB incidence of 5.1 per 100 000 population.

Participants:

All people in BC who initiated at least 90 days of dialysis between January 2012 and May 2017 were included in the study. People were excluded if they were <18 years of age or had a prior history of active TB diagnosis or treatment for latent TB.

Methods:

A retrospective cohort was created of British Columbians who initiated dialysis between 2012 and 2017. Individuals were stratified into a screened and nonscreened group. Multivariable Cox regression was used to determine the association between latent TB screening and the development of active TB. The primary outcome was incident active TB, either microbiologically confirmed or clinically diagnosed.

Results:

Of the 3190 people included in the study, 1790 (56.1%) were screened, of which 152 (8.5%) initiated latent TB treatment postscreening. During follow-up, incident active TB was diagnosed in 6 (0.3%) of the 1790 people screened, compared with 11 (0.8%) of the 1400 people who received no screening. In multivariable analysis, latent TB screening and treatment was associated with a significant reduction in the rate of active TB (adjusted hazard ratio = 0.3, 95% confidence interval = 0.1-0.8; P < .01).

Limitations:

This was an observational retrospective study and the potential for unmeasured confounding should be carefully assessed.

Conclusions:

These findings suggest that systematically screening and treating people initiating dialysis can significantly decrease the rate of active TB in this high-risk population. Given the importance of screening high-risk groups, the results from this analysis could inform scale-up of TB screening in dialysis programs in other low incidence regions. Trial registration is not applicable as this was a retrospective cohort analysis and not a randomized trial.

Renaissance of Tuberculosis in the 19905: Lessons for the Nephrologist

Objective

To call attention to the worldwide increase in tuberculosis and to review the disease in peritoneal dialysis patients.

Data Sources

Recent epidemiological publications.

Data Extraction

Epidemiological data summarized in tables and diagnostic and therapeutic recommendations reviewed.

Conclusions

Tuberculosis is on the rise worldwide. Multiple drug-resistant strains are emerging, causing therapeutic problems. The role of atypical mycobacterial infections in continuous ambulatory peritoneal dialysis (CAPD) is reviewed. Early diagnosis of cases and thorough chemotherapy are advocated.

Mycobacterium tuberculosis infections in solid organ transplantation: Guidelines from the infectious diseases community of practice of the American Society of Transplantation

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of tuberculosis in the pre- and post-transplant period. The challenges of screening for both latent and active TB in the setting of transplantation are reviewed. The use of interferon gamma release assays for detection of latent tuberculosis is discussed and compared to tuberculin skin testing. Given the limitations of both testing modality, it is important to consider exposure history and chest imaging. The clinical manifestations of active tuberculosis in transplantation are covered. New recommendations for treatment of latent tuberculosis and active tuberculosis are included.

Bacterial pneumonia in kidney transplant recipients

Bacterial pathogens are the most frequent cause of pneumonia after transplantation. Early after transplantation, recipients are at higher risk for nosocomial infections. The most commonly encountered pathogens during this period are gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa …), but gram-positive coccus such as Staphylococcus aureus or Streptococcus pneumoniae and anaerobic bacteria can also be found. Empirical antibiotic therapy should be guided by previous colonisation of the recipient and bacterial resistance pattern in the hospital. Six months after transplantation, pneumonias are mostly due to community-acquired bacteria (S. pneumonia, H. influenza, Mycoplasma, Chlamydia and others). Opportunistic pathogens take advantage of the state of immunosuppression which is usually highest from one to six months after transplantation. During this period, but also occurring many years later in the setting of a chronically depressed immune system, bacterial pathogens with low intrinsic virulence can cause pneumonia. The diagnosis of pneumonia caused by opportunistic pathogens can be challenging. The delay in diagnosis preventing the early instauration of adequate treatment in kidney transplant recipients with a depressed immune system, frequently coupled with co-morbid conditions and a state of frailty, will affect prognosis and outcome, increasing morbidity and mortality. This review will focus on the most common opportunistic bacterial pathogens causing pneumonia in kidney transplant recipients: Legionella, Nocardia, Mycobacterium tuberculosis/nontuberculous, and Rhodococcus. Recognition of their specificities in the setting of immunosuppression will allow early diagnosis, crucial for initiation of effective therapy and successful outcome. Interactions with immunosuppressive therapy should be considered as well as reducing immunosuppression if necessary.

Tuberculosis and Transplantation

Mycobacterium tuberculosis is a major opportunistic pathogen in transplant recipients. Compared to that in the general population, the frequency of tuberculosis (TB) is 10 to 40 times higher in hematopoietic stem cell transplant (HSCT) recipients and 20 to 74 times higher in solid-organ transplant (SOT) recipients. Transplant recipients with TB are also more likely to develop disseminated disease, have longer time to definitive diagnosis, require more invasive diagnostic procedures, and experience greater anti-TB treatment-related toxicity than the general population. Specific risk factors for TB in SOT recipients include previous exposure to M. tuberculosis (positive tuberculin skin tests and/or residual TB lesions in pretransplant chest X ray) and the intensity of immunosuppression (use of antilymphocyte antibodies, type of basal immunosuppression, and intensification of immunosuppressive therapy for allograft rejection). Risk factors in HSCT recipients are allogeneic transplantation from an unrelated donor; chronic graft-versus-host disease treated with corticosteroids; unrelated or mismatched allograft; pretransplant conditioning using total body irradiation, busulfan, or cyclophosphamide; and type and stage of primary hematological disorder. Transplant recipients with evidence of prior exposure to M. tuberculosis should receive treatment appropriate for latent TB infection. Optimal management of active TB disease is particularly challenging due to significant drug interactions between the anti-TB agents and the immunosuppressive therapy. In this chapter, we address the epidemiology, clinical presentation, diagnostic considerations, and management strategies for TB in SOT and HSCT recipients.

Globalization of pediatric transplantation: The risk of tuberculosis or not tuberculosis

The risk of TB among pediatric SOT recipients increases as the globalization of medical care continues to broaden. Unlike adults, children and especially infants are more susceptible to TB as a complication after transplantation. Little data exist regarding the true incidence of TB and the optimal risk-based management of this very vulnerable population. Here, we highlight the theoretical and practical issues that complicate the management of these patients and pose some questions that should be addressed when managing these patients. More data are needed to provide optimal guidance of the best diagnostic and management practices to this unique population.

Tuberculosis and chronic kidney disease: an emerging global syndemic

The link between chronic kidney disease (CKD) and tuberculosis (TB) has been known for more than 40 years, but the interaction between these 2 diseases is still poorly understood. Dialysis and renal transplant patients appear to be at a higher risk of TB, in part related to immunosuppression along with socioeconomic, demographic, and comorbid factors. Meanwhile, TB screening and diagnostic test performance is suboptimal in the CKD population, and there is limited evidence to guide protocols. Given the increasing prevalence of CKD in TB endemic areas, a merging of CKD and TB epidemics could have significant public health implications, especially in low- to middle-income countries such as India and China, that are experiencing rapid increases in CKD prevalence and account for more than one-third of global TB prevalence. To begin addressing TB-CKD, a clear understanding of the relationship between these 2 conditions needs to be established, and consistent, evidence-based screening and treatment guidelines need to be developed.

Infection Prevention and Control Issues After Solid Organ Transplantation

Infections are an important cause of morbidity and mortality in solid organ transplant recipients. Consequently, infection prevention is an essential component of any organ transplant program. Given their frequent and often prolonged contact with the healthcare system, solid organ transplant recipients are at high risk for healthcare-associated infections, including those caused by antibiotic-resistant organisms. In this chapter we review several different healthcare-associated infections of importance to transplant recipients, including those caused by bacterial, viral, and fungal organisms. We also describe infection prevention and control strategies applicable to this patient population. These practices focus on clinical interventions and environmental controls designed to prevent the spread of potentially pathogenic organisms in the healthcare setting. We also describe post-exposure interventions applicable to solid organ transplant recipients exposed to potential pathogens in order to reduce their risk of subsequent infection.

Epidemic Intelligence Service investigations of respiratory illness, 1946-2005

Infectious respiratory pathogens were the suspected cause of 480 outbreaks investigated by the Centers for Disease Control and Prevention's Epidemic Intelligence Service officers during 1946-2005. All epidemic-assistance investigation reports and associated articles from scientific journals were reviewed. Investigations identified 25 different infectious respiratory pathogens including, most frequently, tuberculosis, influenza, and legionellosis. Other bacterial-, viral-, and fungal-related pathogens also were identified. Epidemic-assistance investigations were notable for first identifying Legionnaires disease and Pontiac fever, hantavirus pulmonary syndrome, and new strains of human and avian influenza, as well as emerging challenges (e.g., multidrug-resistant tuberculosis and pneumococcus). The investigations provided clinical insights into such diseases as pulmonary anthrax and identified high risks of serious respiratory illnesses for persons infected with human immunodeficiency virus, other immunocompromised persons, and persons with diabetes. They identified settings placing persons at high risk of acquiring disease, including nursing homes, prisons, homeless shelters, and hospitals. Travel also placed persons at risk. Key environmental factors related to spread of diseases and occupational risks for brucellosis and psittacosis were identified. The outbreak investigations constitute a wealth of prevention experience and provide the basis for recommendations to mitigate outbreaks and reduce future risks.

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients

Heat and moisture exchangers and breathing system filters are intended to replace the normal warming, humidifying and filtering functions of the upper airways. The first part of this review considered the history, principles of operation and efficiency of these devices. The aim of this part of the review is to summarise recent guidelines on the use of these devices and outline the problems that can occur. In particular, the effect of these devices on gas analysis, dead space, resistance to gas flow and blockage of the breathing system is considered. In children, it is important to consider the addition of dead space and resistance to gas flow. A body weight of 2.5 kg is probably the lower weight limit for use with heat and moisture exchangers, and 3 kg for filters. The resistance to gas flow of a heat- and moisture-exchanging filter added to a Mapleson F breathing system can cause a delay in the induction of anaesthesia.

Mass casualty respiratory failure

PURPOSE OF REVIEW

The severe acute respiratory syndrome epidemic of 2002-2003, recent natural catastrophes, burgeoning concerns regarding intentional catastrophes, and the looming threat of an influenza pandemic have focused attention on large-scale, survivable respiratory failure. In this article, we review appropriate medical equipment, treatment space, and strategies to augment health professional staff in response to a massive increase in need for sustained critical care.

RECENT FINDINGS

There is insufficient modern healthcare experience with mass casualty respiratory failure to develop evidence-based preparedness efforts. For this reason, initial efforts to augment critical care capability in response to disasters have relied on extrapolation from the routine critical care knowledge base, military medicine, critical care transport, and expert opinion. We review recently published documents on augmenting supplies of positive pressure ventilation equipment, ongoing projects for increasing health professional staff, and infection control issues during epidemics.

SUMMARY

Mass casualty respiratory failure remains a largely unstudied field, but we believe informed decisions about equipment stockpiling and use, the development of creative operational concepts to increase staffing, and the careful implementation of rational infection control practices can lay a foundation for an appropriate response until additional data become available.

Tuberculosis in renal transplant recipients

Tuberculosis (TB) is a frequent infectious complication in patients on renal replacement therapy, as a result of immunosuppression from uremia and drugs in the post-transplantation period. A retrospective study of all renal transplantation patients from 1989 to date was conducted. This study tried to examine the prevalence, course, and outcome of TB in renal transplant recipients. A comparison with the occurrence of TB in other modalities of renal replacement therapy was also made. We also discussed the treatment protocols for TB in this group of patients. No difference in the prevalence, age, or male/female ratio of TB was seen among the 3 modes of renal replacement therapy. TB of the lung was the more favored site of infection in patients on hemodialysis (77.3%), when compared with those on CAPD (30%) and renal transplant recipients (33.3%). In renal transplant recipients, no deaths occurred due to TB. In 7 patients there was co-infection with cytomegalovirus and in 3 patients there was Aspergillus lung infection.

Implications for management of Mycobacterium tuberculosis infection in adult-to-adult live donor liver transplantation

BACKGROUND

Mycobacterium tuberculosis (TB) infection is a serious opportunistic infection especially in live donor liver transplantation (LDLT). Hepatotoxicity of antituberculous agents and hazardous drug interaction with immunosuppressants may render the graft more susceptible to injury.

AIM OF STUDY

To review our experience of management of TB infection in liver transplant recipients including LDLT.

PATIENTS AND METHODS

A total of 397 liver transplantations were performed in the University of Hong Kong Medical Centre from January 1991 to December 2004. Eight patients (2.0%) developed TB infection after transplantation (LDLT: n=6, DDLT: n=2) and their clinical courses were reviewed.

RESULT

The mean time of developing TB infection after liver transplantation was 9 months (range 4-20 months). Anti-TB treatment was administered for a mean duration of 12.7 months (11-18 months). None of our patients developed antituberculous drug-induced hepatotoxicity or had unwanted drug interaction. With a mean follow-up of 65 months (range 18-102 months), one patient died due to the recurrence of hepatocellular carcinoma.

CONCLUSION

High index of suspicion for TB infection should be warranted for a history of cough and fever after liver transplantation. No notable difference was observed in the natural history and management of TB infection between LDLT and DDLT. The use of antituberculous drugs is safe in liver transplant recipients provided that liver function is closely monitored and the dosage of immunosuppressants is adjusted accordingly.

Preventing the transmission of pathogenic microbes during anesthesia

During anesthesia, a breathing system may be used for more than one patient. Any microbes expelled by one patient, whether gasborne in the form of droplets or liquidborne in sputum, should be prevented from entering the breathing system. Breathing system filters are intended to reduce the risk of cross infection during anesthesia and intensive care from these routes. The Medicines and Healthcare products Regulatory Agency published a report in 2004 that included data on the gasborne filtration performance of 104 different filters available on the UK market. A wide range in filtration performance was found. Filters intended for use with pediatric patients do not appear to offer the same level of protection as those intended for use with adult patients, despite the lower flow used to challenge these filters. Recent government initiatives to reduce the prevalence of tuberculosis and hepatitis C in England have again focused interest on the ability of filters to reduce the risk of cross infection from these particular microbes arising from patients who may not be aware that they are harboring the disease. Currently, there are no requirements for the level of filtration that breathing system filters have to provide, either in standards or from professional bodies.

Fast ligation-mediated PCR, a fast and reliable method for IS6110-based typing of Mycobacterium tuberculosis complex

IS6110 restriction fragment length polymorphism (RFLP) analysis is the most widely applied method for strain differentiation of Mycobacterium tuberculosis complex. We have previously described mixed-linker PCR, an IS6110-based PCR method that favorably compared with other typing methods for M. tuberculosis complex according to reproducibility and ability to differentiate between strains. Here we report the further development of this method, called fast ligation-mediated PCR (FLiP), which allows analysis of strains within one working day and starting from less than 1 ng of mycobacterial DNA or a crude cell lysate. Blinded analysis of a standard set of 131 M. tuberculosis complex and nontuberculous isolates showed the ability to differentiate 81 types among 90 M. tuberculosis complex isolates with 84 different IS6110 RFLP fingerprint patterns and detected 97% of the 31 duplicate samples. We suggest that FLiP can serve to rapidly detect chains of transmission prior to starting high-throughput analysis or standard IS6110 RFLP. It may as well serve as a secondary typing technique for other, non-IS6110-based methods.

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.

Molecular Epidemiology: A Tool for Understanding Control of Tuberculosis Transmission

One of the primary goals of tuberculosis control programs is to interrupt the transmission of Mycobacterium tuberculosis. The development of several genotyping tools has allowed tracking of strains of M. tuberculosis as they spread through communities. Studies that have combined the use of genotyping with conventional epidemiologic investigation have increased the understanding of the transmission and pathogenesis of tuberculosis. This article reviews some of the lessons learned using these new epidemiologic tools.

Mycobacterium tuberculosis Infection in Recipients of Solid Organ Transplants

Tuberculosis is a serious opportunistic infection that may affect transplant recipients. The incidence of tuberculosis among such persons is 20-74 times higher than that for the general population, with a mortality rate of up to 30%. The most common form of acquisition of tuberculosis after transplantation is the reactivation of latent tuberculosis in patients with previous exposure. Clinical presentation is frequently atypical and diverse, with unsuspected and elusive sites of affection. Manifestations include fever of unknown origin and allograft dysfunction. Coinfection with other pathogens is not uncommon. New techniques, such as PCR and quantification of interferon- gamma , have been developed to achieve more-rapid and -accurate diagnoses. Treatment requires control of interactions between antituberculous drugs and immunosuppressive therapy. Prophylaxis against latent tuberculosis is the main approach to treatment, but many issues remain unsolved, because of the difficulty in identifying patients at risk (such as those with nonreactive purified protein derivative test results) and the toxicity of therapy.

Mycobacterial infection in a series of 1261 renal transplant recipients

OBJECTIVE

To describe the incidence and clinical characteristics of mycobacterial infection in renal transplant recipients.

METHODS

We retrospectively analyzed the cases of mycobacterial infection in a series of 1261 renal transplants carried out in our Unit of Renal Transplantation from 1980 to 2000. Demographic parameters and clinical antecedents such as age, cause of end-stage renal disease, time of follow-up of the graft, previous renal function and type of immunosuppression were considered. Moreover, the clinical onset, diagnostic tools, treatment policy and evolution were studied. The pathogenesis of the different types of mycobacteria isolated was also analyzed. Diagnosis was made with the Ziehl-Neelsen staining method. Culture was performed by the conventional Löwenstein-Jensen method and the Bactec-460 radiometric method.

RESULTS

We found mycobacterial infection in 27 patients (2.1%), due to Mycobacterium tuberculosis in 20 cases, M. kansasii in five patients, and M. fortuitum in two patients. The mean elapsed time from the renal transplant was 20.5 months; the infection appeared in 18 patients during the first eight months after transplantation. The clinical onset was pulmonary infection in 17 cases (12 M. tuberculosis and five M. kansasii); five had urinary symptoms (three M. tuberculosis and two M. fortuitum); three cases of M. tuberculosis infection had abdominal symptoms; another one began with a perineal tuberculous abscess; the rest of the patients were asymptomatic. The types of specimen on which microbiological identification was carried out were, in decreasing order: sputum and/or bronchial washing/pleural aspiration, urine, feces, gastric and peritoneal fluids, bone marrow and blood. The first-line drug isoniazid had the highest resistance index in the susceptibility test. Clinical dissemination was observed in eight patients, four of whom died. Another three patients had a significant impairment in renal function, and in one of these patients an allograft nephrectomy was necessary due to a severe septic syndrome.

CONCLUSIONS

Mycobacterial infection, mainly by M. tuberculosis, has an important impact on kidney transplant recipients, particularly during the first year after surgery. Diagnosis often presents some difficulties, and a delay in treatment represents a determinant factor for the evolution, with a risk of death or permanent damage in renal function. Therefore, early diagnosis is mandatory. When the Mantoux reaction is positive, antituberculous prophylaxis seems advisable.

DNA fngerprinting of Mycobacterium tuberculosis: lessons learned and implications for the future

DNA fingerprinting of Mycobacterium tuberculosis--a relatively new laboratory technique--offers promise as a powerful aid in the prevention and control of tuberculosis (TB). Established in 1996 by the Centers for Disease Control and Prevention (CDC), the National Tuberculosis Genotyping and Surveillance Network was a 5-year prospective, population-based study of DNA fingerprinting conducted from 1996 to 2000. The data from this study suggest multiple molecular epidemiologic and program management uses for DNA fingerprinting in TB public health practice. From these data, we also gain a clearer understanding of the overall diversity of M. tuberculosis strains as well as the presence of endemic strains in the United States. We summarize the key findings and the impact that DNA fingerprinting may have on future approaches to TB control. Although challenges and limitations to the use of DNA fingerprinting exist, the widespread implementation of the technique into routine TB prevention and control practices appears scientifically justified.

Whole-genome comparison of Mycobacterium tuberculosis clinical and laboratory strains

Virulence and immunity are poorly understood in Mycobacterium tuberculosis. We sequenced the complete genome of the M. tuberculosis clinical strain CDC1551 and performed a whole-genome comparison with the laboratory strain H37Rv in order to identify polymorphic sequences with potential relevance to disease pathogenesis, immunity, and evolution. We found large-sequence and single-nucleotide polymorphisms in numerous genes. Polymorphic loci included a phospholipase C, a membrane lipoprotein, members of an adenylate cyclase gene family, and members of the PE/PPE gene family, some of which have been implicated in virulence or the host immune response. Several gene families, including the PE/PPE gene family, also had significantly higher synonymous and nonsynonymous substitution frequencies compared to the genome as a whole. We tested a large sample of M. tuberculosis clinical isolates for a subset of the large-sequence and single-nucleotide polymorphisms and found widespread genetic variability at many of these loci. We performed phylogenetic and epidemiological analysis to investigate the evolutionary relationships among isolates and the origins of specific polymorphic loci. A number of these polymorphisms appear to have occurred multiple times as independent events, suggesting that these changes may be under selective pressure. Together, these results demonstrate that polymorphisms among M. tuberculosis strains are more extensive than initially anticipated, and genetic variation may have an important role in disease pathogenesis and immunity.

Molecular epidemiology of tuberculosis among eight hospitals in New York City, 1996-1997

OBJECTIVE

To determine the molecular epidemiology of tuberculosis isolated from patients cared for at eight hospitals scattered throughout New York City.

MATERIALS AND METHODS

Cases of tuberculosis occurring in 1996 and 1997 at collaborating hospitals were identified, and demographic data were extracted from patient charts. All available isolates were analyzed by IS6110 for genetic relatedness. The molecular fingerprints were compared both to each other and to the larger repository of strains from New York City developed and maintained at the Public Health Research Institute.

RESULTS

One hundred and eighty cases were fully characterized. Compared with New York City cases, study patients were more likely to be Asian and less likely to be non-Hispanic blacks. Overall, 97 (54%) of the cases were clustered with respect to other study strains or with respect to the other New York City isolates. Clustered strains were significantly more likely to be from non-Hispanic blacks or patients born in the United States. The largest cluster (n = 17) was the "W" strain previously associated with an outbreak of multidrug-resistant tuberculosis in New York City. In the current study, the majority of W strain isolates were fully drug-susceptible.

CONCLUSIONS

High rates of genetically related tuberculosis continue to occur among patients in New York City, in spite of improved control of nosocomial outbreaks and dramatic decreases in the overall case rates. The use of molecular techniques to suggest patterns of transmission has become essential in developing and assessing routine tuberculosis control strategies.

Value of Mycobacterium tuberculosis fingerprinting as a tool in a rural state surveillance program

OBJECTIVE

This study demonstrates the value of Mycobacterium tuberculosis fingerprinting used in conjunction with traditional epidemiologic methods to identify smoldering outbreaks of tuberculosis in endemic areas where background rates of tuberculosis are high.

METHODS

IS6110 DNA fingerprinting was performed on isolates of M tuberculosis from verified cases of tuberculosis in Alabama from 1994 to 1998. A statewide database groups isolates into "clusters" and tracks them cumulatively over time. A large cluster was identified and was secondarily investigated using traditional epidemiologic methods.

RESULTS

Twenty-five isolates were found to be identical by fingerprinting analysis. Patients were living within 10 counties across the state, and 12 cases were localized to a single county. This represented an ongoing, statewide tuberculosis outbreak previously unrecognized by local and state health officials. Secondary investigation of the cases revealed the primary sites of transmission to be a correctional facility and two homeless shelters.

CONCLUSIONS

Population surveillance using M tuberculosis fingerprinting was successfully utilized to detect a significant and smoldering tuberculosis outbreak. Measures are currently in place to identify and prevent further transmission in the involved locations.

Mycobacterial infections in patients with chronic renal disease

In this article, the authors have provided a comprehensive review of TB and MOTT infections in patients on renal dialysis and receiving kidney transplants. Because most published series are small retrospective studies or case reports, there are several uncertainties still involved in the diagnosis and treatment of such patients. Unanswered questions include selection of optimal dosage and duration of therapeutic agents; the best tests for screening and diagnosis, especially in high prevalence areas; and the best management of MOTT infections because of unavailability of highly effective therapy.

Detection of unsuspected cases of nosocomial transmission of tuberculosis by use of a molecular typing method

The aim of this study was to use restriction fragment length polymorphism to detect unsuspected cases of nosocomial transmission of tuberculosis (TB) among patients who had been admitted to a university hospital. One hundred fifty-one samples of Mycobacterium tuberculosis isolated from patients with pulmonary TB were studied. The isolates from 37 patients (24.5%) defined 11 clusters. None of the patients infected with these cluster isolates had hospital stays that coincided with one another, and for 5.4% of the patients, the epidemiological link was clearly outside the hospital. Previous incarceration was associated with infection with cluster isolates. In addition, 109 patients without TB (41 of whom were infected with human immunodeficiency virus) who shared a room with patients who had TB were followed for 18-60 months. Among the patients who survived, secondary cases of TB due to nosocomial transmission were not detected.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Hospitals in England are failing to follow guidance for tuberculosis infection control - results of a National Survey

Tuberculosis outbreaks can occur in hospitals if adequate infection control is not in place. UK guidelines on the prevention of tuberculosis transmission have recently been published. A national survey of acute NHS Trusts in England was conducted to evaluate whether tuberculosis infection control in hospitals is consistent with the new guidance. There was a 72% response rate (144 NHS Trusts). Sixty percent of Trusts had updated their tuberculosis infection control plans since the new guidance was published. Even trusts with updated plans failed to meet guidance in many areas. Thirty-five percent of Trusts had negative pressure facilities for the isolation of infectious tuberculosis patients. Depending on the risk category of the patient, 45-67% of Trusts met guidelines for isolation of infectious patients. Patients frequently left isolation for non-medical reasons. Only a minority of Trusts complied with guidance for respiratory protection of staff and visitors. These findings suggest that many Trusts remain at risk of outbreaks of tuberculosis and therefore need to re-examine infection control procedures and the availability of isolation facilities.

Genetic heterogeneity in Mycobacterium tuberculosis isolates reflected in IS6110 restriction fragment length polymorphism patterns as low-intensity bands

Mycobacterium tuberculosis isolates with identical IS6110 restriction fragment length polymorphism (RFLP) patterns are considered to originate from the same ancestral strain and thus to reflect ongoing transmission. In this study, we investigated 1,277 IS6110 RFLP patterns for the presence of multiple low-intensity bands (LIBs), which may indicate infections with multiple M. tuberculosis strains. We did not find any multiple LIBs, suggesting that multiple infections are rare in the Netherlands. However, we did observe a few LIBs in 94 patterns (7.4%) and examined the nature of this phenomenon. With single-colony cultures it was found that LIBs mostly represent mixed bacterial populations with slightly different RFLP patterns. Mixtures were expressed in RFLP patterns as LIBs when 10 to 30% of the DNA analyzed originated from a bacterial population with another RFLP pattern. Presumably, a part of the LIBs did not represent mixed bacterial populations, as in some clusters all strains exhibited LIBs in their RFLP patterns. The occurrence of LIBs was associated with increased age in patients. This may reflect either a gradual change of the bacterial population in the human body over time or IS6110-mediated genetic adaptation of M. tuberculosis to changes in the environmental conditions during the dormant state or reactivation thereafter.

False molecular clusters due to nonrandom association of IS6110 with Mycobacterium tuberculosis

We sought to determine whether nonrandom association of IS6110 with Mycobacterium tuberculosis could result in false-positive clustering in unselected collections of isolates. We typed 196 strains of M. tuberculosis from an unselected community-based study in northern Tanzania by IS6110 and polymorphic GC-rich repetitive-sequence (PGRS) methodologies. The strains were analyzed by Gelcompar computer software. Analysis of 13 out of 25 groups showed that isolates with identical IS6110 and PGRS patterns were likely to be the same strain. Some IS6110 groups containing strains with identical PGRS patterns had similar IS6110 patterns that differed only by movement of the element. Isolates assigned to a single group (i.e., group 11) on the basis of sharing an identical IS6110 fingerprint pattern did not share identical PGRS fingerprint patterns. Six out of the nine bands in these isolates were in hot-spot locations, as previously defined. This indicates that nonrandom association may result in false-positive clustering in unselected community-based studies. Only strains with identical PGRS and IS6110 patterns are likely to be recently transmitted.

Aspects of Pulmonary Infections After Solid Organ Transplantation

The increasing number of solid organ transplant (SOT) recipients have high rates of pulmonary infections due to bacterial, fungal, and viral pathogens. These patients have unique sets of factors predisposing to infection. Lung and heart-lung transplants are associated with particularly high infection rates. The prominence of cytomegalovirus (CMV) as a pathogen in all subsets of SOT patients has led to new strategies for prophylaxis, detection, and treatment of CMV pneumonitis. Progress is similarly being made in managing fungal and bacterial infections. Advances in liver, kidney, heart, and lung transplantation are being discussed, with further attention to specific pathogens (ie, CMV, Aspergillus, Pneumocystis carinii, and Mycobacterium tuberculosis).

The potential for dissemination of Mycobacterium tuberculosis through the anesthesia breathing circuit

BACKGROUND

Respiratory pathogens that pass through the anesthesia breathing system potentially can infect other patients. This study was designed to determine if bacteria can pass through contemporary anesthesia breathing systems and if the environment within the machine is hostile to these organisms.

METHODS

Staphylococcus aureus, Pseudomonas aeruginosa, and Mycobacterium tuberculosis were nebulized into the expiratory limb of an anesthesia breathing circuit and collected from the inspiratory and expiratory limbs in an impinger system that provided a quantitative determination of the number of organisms entering the circuit and the number that would reach the patient in the inspiratory gas. Bacteria were collected before, during, and after nebulization. A second experiment determined if a saturated solution of soda lime was bactericidal.

RESULTS

When the gas flow through the circuit was interrupted for < 1 h following the nebulization period, large numbers of microorganisms (1 x 10(3) to 1 x 10(5), around 100% of the nebulized organisms) were collected from the inspiratory gas. Soda lime itself was not bactericidal for any of the organisms tested, but solutions of this material with a pH of 12 were bactericidal.

CONCLUSION

Cross contamination between patients may occur unless the gas flow through the anesthesia breathing system is interrupted for > 1 h.

Infection control in the bronchoscopy suite. A review

Bronchoscopy can occasionally transmit disease. Infection control in the bronchoscopy suite is especially important because of the risk of transmitting HIV or tuberculosis. Many case reports, patient series, and small studies have been published, but little comprehensive guidance is available for clinicians who wish to learn more about the problem and prevent it. We review the literature and describe three ways in which bronchoscopy can cause disease: by transmitting infections between patients, by transferring microorganisms within a patient, and by triggering coughing that can cause airborne infection of patients or health-care workers. Recommendations for infection control are listed; they include installing powerful air filters, using disposable bronchoscope suction valves, manually cleaning all equipment before disinfection, controlling patient coughing, and in some cases, giving patients prophylactic antibiotics.

Nonrandom association of IS6110 and Mycobacterium tuberculosis: implications for molecular epidemiological studies

IS6110 restriction fragment length polymorphism typing is now established as the primary typing method for Mycobacterium tuberculosis. It has been assumed that the position of bands is random. Thus, the discrimination of the technique increases in proportion to the copy number. Two collections of M. tuberculosis were investigated to test this hypothesis. We identified 33 positions in isolates from a Tanzanian collection and 25 positions in isolates from a London, United Kingdom, collection where bands were significantly more likely to be present than would be expected by chance. These data suggest that band position is not random, and this possibility may have an impact on the interpretation of molecular epidemiological studies of M. tuberculosis.

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.

Chest radiographic findings in patients with tuberculosis with recent or remote infection

To determine if chest radiographic findings differ in adult tuberculosis patients with recent and remote infection, we reviewed the chest radiographs of 103 patients with tuberculosis in Los Angeles and performed RFLP analyses of their Mycobacterium tuberculosis isolates. Patients whose isolates had identical or closely related RFLP patterns were considered a "cluster." Most patients in large clusters (more than seven patients) had tuberculosis from recent infection, whereas most unclustered patients had tuberculosis from remote infection. Mediastinal adenopathy or pleural effusions were classified as typical of recent infection, and upper lobe infiltrates, cavitation, or fibrosis were classified as characteristic of remote infection. Radiographic patterns were typical of remote infection in 62% of patients and were characteristic of recent infection in 23% of patients. The distribution of these radiographic patterns was similar in clustered and unclustered patients, both with or without human immunodeficiency virus (HIV) coinfection. However, mediastinal adenopathy and pleural effusions were significantly more common in HIV-infected patients. We conclude that: (1) chest radiographic findings in adults with tuberculosis of recent infection are similar to those in patients with remote infection; (2) the distinctive chest radiographic findings in HIV-infected patients with tuberculosis are not due to an increased frequency of recent infection.