Prevention of lung infections associated with human immunodeficiency virus infection.

Current evidence indicates that the length of survival for patients with the acquired immunodeficiency syndrome (AIDS) is increasing, thereby affording a greater opportunity for strategies designed to prevent the infectious diseases that mark the syndrome. Because these infections may occur at different stages of immunosuppression caused by the human immunodeficiency virus (HIV), effective application of preventive measures depends not only on detection of HIV infection but also on the use of staging indicators. The diseases that serve to define AIDS, such as Pneumocystis carinii pneumonia, tend to occur late in the course of HIV infection and often when the T helper lymphocyte (CD4+ cells) count is less than 0.2 x 10(9)/l. Other infections, such as tuberculosis and pyogenic bacterial pneumonia, may develop at any point after HIV infection has occurred. Given this relation between the degree of immunosuppression and the occurrence of particular pulmonary infections, different preventive interventions should be applied at different times. It is now known that the incidence of several of the pulmonary infections that are common in patients with HIV infection can be reduced by prophylactic measures. Pneumocystis pneumonia is decreased in frequency by any one of several prophylactic agents, the best established being pentamidine administered as an inhaled aerosol. The role of isoniazid in the chemoprophylaxis of tuberculosis in patients not infected with HIV is well established. Although there is little evidence of benefit so far from isoniazid in HIV infected patients with a positive tuberculin skin test response, it is logical to assume that there could be some effect. The use of pneumococcal polysaccharide vaccine may also be of some benefit in reducing the frequency of pneumococcal pneumonia in patients with AIDS. In addition to these specific measures, the antiretroviral agent zidovudine decreases both the frequency and the severity of opportunist infections, at least during the first few months of treatment. A comprehensive strategy for prevention of HIV associated lung infection first requires detection of HIV seropositivity, staging the immunosuppression by the CD4+ cell count, and determining whether tuberculous infection is present by a tuberculin skin test. All seropositive individuals should be given pneumococcal vaccine and those with evidence of tuberculosis infection should be treated with isoniazid for one year. Zidovudine should probably be started when CD4+ cell counts are in the range 0.4-0.5 x 10(9)/l and prophylaxis against pneumocystis infection when CD4+ cell counts are in the range 0.2-0.3 x 10(9)/l.     

AIDS and the lung. Introduction.

Damage to the immune system induced by the human immunodeficiency virus (HIV) leads to a spectrum of opportunistic infections of which the lung is the most common site. In Europe and North America, pneumocystis carinii pneumonia is the presenting symptom in 64% of cases of acquired immunodeficiency syndrome (AIDS) and occurs at some point in 80% of AIDS victims. This infection is less common in Africa, where tuberculosis is the predominant opportunistic infection. Other AIDS-related lung infections that are gaining in prevalence include pneumonia due to pyogenic bacteria, pulmonary infection with Mycobacterium tuberculosis, and lymphoid interstitial pneumonitis. In addition, there is evidence that the lung may be extensively involved in Kaposi's sarcoma. Given the importance of the lung as a site for AIDS-related opportunistic infections, respiratory physicians will be required to become more involved in the diagnosis and management of AIDS cases.     

Musculoskeletal manifestations of human immunodeficiency virus infection

Musculoskeletal manifestations of the human immunodeficiency virus (HIV) are common and are sometimes the initial presentation of the disease. Knowledge of the conditions affecting muscle, bone, and joints in HIV-infected patients is essential for successful management. Myopathies may be caused by pyogenic infection (eg, pyomyositis), idiopathic inflammation (eg, polymyositis), or drug effect (eg, AZT myopathy). Characteristic skeletal infections, such as tuberculosis and bacillary angiomatosis, require a high index of suspicion for accurate diagnosis. Neoplastic processes, such as non-Hodgkin's lymphoma and Kaposi's sarcoma, occur more frequently as the immune system deteriorates. Inflammatory and reactive arthropathies are more prevalent in HIV-positive than HIV-negative individuals and include Reiter's syndrome, psoriatic arthritis, HIV-associated arthritis, painful articular syndrome, acute symmetric polyarthritis, and hypertrophic osteoarthropathy. Patients with atypical musculoskeletal complaints and a suspected history of exposure should be tested for HIV.     

Mycobacterium tuberculosis in the acquired immunodeficiency syndrome

Patients with human immunodeficiency virus (HIV) infection, with or without the diagnosis of acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC), have an increased incidence of tuberculosis, especially of an extrapulmonary nature. The condition is associated with significant morbidity and mortality. The reported incidence of the combination of tuberculosis and AIDS varies between 4% and 10% of AIDS patients, with a higher incidence noted in the male, inner-city, intravenous-drug-abuser population. Clinical findings may reflect the site of infection, but are often nondiagnostic. Diagnosis often requires biopsy for histopathologic evaluation and tissue culture to document the presence of granulomas and mycobacterial organisms. Universal body fluid precautions among these patients are mandatory, and respiratory isolation should be maintained during diagnostic evaluation and early treatment. These patients usually respond to standard antituberculosis therapy. Physicians should maintain a high index of suspicion of tuberculosis in patients with HIV infection. Conversely, the diagnosis of HIV infection should be considered in patients with unusual manifestations of tuberculosis. Because tuberculosis is one of the few potentially curable infections in the AIDS patient, recognition of its presence is crucial.     

Tuberculosis and HIV: estimates of the overlap in England and Wales.

BACKGROUND: A study was designed to determine the extent of the interaction between tuberculosis and human immunodeficiency virus infection in England and Wales. METHODS: Data were obtained from the United Kingdom national AIDS surveillance and the Medical Research Council tuberculosis notification surveys in England and Wales (1983 and 1988). The proportion of patients reported with AIDS known to have had tuberculosis and the proportion of patients notified with tuberculosis known to have HIV infection were estimated. RESULTS: Of the 4360 patients with AIDS reported by 30 June 1991, 200 (4.6%) were in patients reported to have had tuberculosis. Only one of the 3002 patients (0.03%) reported in the 1983 survey of tuberculosis notifications in England and Wales was known to be infected with HIV compared with nine of 2163 patients (0.42%) in the 1988 survey. CONCLUSION: Although the reported number of cases of HIV infection with tuberculosis in this country is increasing it remains small. Complete reporting of cases of AIDS and notification of cases of tuberculosis are essential to enable the two infections to be monitored as the HIV epidemic develops. Special studies, such as those reported here, will need to be undertaken regularly to assess the future extent of the interaction.     

Occupational blood-borne diseases in surgery

BACKGROUND: Human immunodeficiency virus (HIV), hepatitis B (HBV), and hepatitis C (HCV) infections are transmitted by blood exposure. Surgeons have been concerned about the risks of blood exposure in the operating room as a potential source of occupational infections from these viruses. The actual risk and frequency of operating room transmission remains poorly understood by many surgeons. METHODS: The pertinent recent literature on the pathophysiology, diagnosis, prevention, and treatment of HIV, HBV and HCV were reviewed to address the current understanding of these viruses as occupational risks to surgeons. RESULTS: HIV transmission to surgeons has not been documented in the United States by the Centers for Disease Control. HIV transmission from a surgeon to a patient in the environment of the operating room, as well as transmission from an HIV-infected surgeon to a patient, has not been documented. HBV infection of surgeons has declined with the general acceptance of the HBV vaccine. HCV infection remains a real risk for transmission in the operating room, given that no vaccine is currently available and that the overall number of chronically infected patients remains quite high. CONCLUSION: The risk of occupational infection from known viral pathogens for surgeons is low, but it is not zero. Effective barriers, modified patterns of behavior, and prompt responses to blood exposure events are the best methods for prevention.     

Anesthesia in HIV-infected children

In 2005, it was estimated that 2.3 million children below 15 years of age were living with human immunodeficiency virus (HIV)/AIDS and 570,000 children below 15 years died. Maternal-infant or vertical transmission is the most common mode of HIV infection in children. As transplacental passage of maternal anti-HIV antibodies, diagnosis of HIV infection in young infants relies on virologic assays. Infants older than 18 months of age can be diagnosed by serology alone. Pediatric HIV infections are classified according to Center for Disease Control and Prevention 1994 revised classification system. The understanding of viral pathogenesis, the development of highly active antiretroviral therapy, and the ability to quantitate viral burden have led to significant reduction in disease progression and morbidity in HIV-infected children. As survival improves, these children will require anesthesia care and pain treatment during the course of their illness. Considerations for the anesthesiologist include: possible involvement of multiple organ systems, adverse reactions and drug interactions of antiretroviral agents and adequate infection control to prevent HIV transmission in hospital and other infections to the immunocompromised patients. Finally, care should be taken not to violate confidentiality.     

Human Immunodeficiency Disease: How Should It Affect Surgical Decision Making?

Background  The ever-increasing prevalence of human immunodeficiency virus (HIV) infection and the continued improvement in clinical management has increased the likelihood of surgery being performed on patients with this infection. The aim of the review was to assess current literature on the influence of HIV status on surgical decision-making. Methods  A literature review was performed using MEDLINE articles addressing “human immunodeficiency virus,” “HIV,” “acquired immunodeficiency syndrome,” “AIDS,” “HIV and surgery.” We also manually searched relevant surgical journals and completed the bibliographic compilation by collecting cross references from published papers. Results  Results of surgery between noninfected and HIV-infected individuals and between HIV-infected and acquired immunodeficiency syndrome (AIDS) patients are variable in terms of morbidity, mortality, and hospital stay. The risk of major surgery is not unlike that for other immunocompromised or malnourished patients. The multiple co-morbidities associated with HIV infection and the availability of highly active antiretroviral therapy must be considered when assessing and optimizing the patient for surgery. The clinical stage of the patient’s disease should be evaluated with a focus on the overall organ system function. For patients with advanced HIV disease, palliative surgery offers relief of acute problems with improvement in the quality of life. When indicated, diagnostic surgery assists with further decision-making in the medical management of these patients and hence should not be withheld. Conclusion  HIV infection should not be considered a significant independent factor for major surgical procedures. Appropriate surgery should be offered as in normal surgical patients without fear of an unfavorable outcome.     

Transplant tourism and donor-derived parasitic infections

Transplant tourism, travel with the intent of receiving or donating a transplanted organ, has grown immensely in the past decade but is not without risks. Solid organ donors are potential carriers of infection and rates of infection are high in transplant recipients. Returning transplant recipients should be screened for blood-borne pathogens, including human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV), as well as bacteremia, urinary tract infections, and other endemic pathogens (malaria, tuberculosis, Chagas disease, and so on). Efforts should be made to optimize posttransplantation prophylaxis against infection. Although donor-derived parasitic infections are rare, rates of morbidity and mortality are high. Increases in world travel and migration will likely contribute to increases in donor-derived parasitic infection. Appropriate epidemiological screening and diagnostic testing, including blood smears, serology, and stool assays, may help reduce the risk of such transmission.     

HIV infection in Africa. Clinical and therapeutical research

A MAJOR HEALTH PROBLEM: Human Immunodeficiency Virus (HIV) infection is a major public health problem in sub-Saharan Africa and the care of HIV-infected patients is limited by the lack of resources. Clinical research can play a major role to assess the benefit of preventive and/or curative measures adapted to the context of these countries. To illustrate advances and gaps in HIV/AIDS clinical research in Africa, we explored three issues relevant to this research: opportunistic infections in adults, mother-to-child transmission of HIV and the ethical questions. EPIDEMIOLOGY: Epidemiological African studies have shown: the omnipresence of tuberculosis, first cause of death among HIV+ patients; the frequency of bacterial infections, first cause of serious morbidity and second cause of death; the high frequency of toxoplasmosis, cryptococcal meningitis, isosporiasis, cryptosporidiasis, and other infectious syndromes of unknown etiology. More research efforts need to be done for improving tuberculosis diagnosis, compliance to treatment (evaluation of Directed Observed Therapy), resistance to treatment and primary chemoprophylaxis which has shown clear short term benefit but median term interest remains to be demonstrated. Chemoprophylaxis of opportunistic infections other than tuberculosis needs also to be evaluated: cotrimoxazole reduces the short term mortality of HIV+ patients with tuberculosis and the early serious morbidity of HIV+ patients without tuberculosis. TRANSMISSION: Mother-to-child transmission of HIV can occur during pregnancy, during delivery and the postnatal period by breastfeeding, a common practice in Africa. The overall risk of vertical transmission is estimated to be 30% but the attributable part of breastfeeding needs to be further explored. Beyond the prevention of sexual transmission of HIV among childbearing women and family planning for HIV+ women, interventions aimed to reduce mother-to-child transmission depend on the availability or not of a proposing and realising an HIV counselling and testing: antiretroviral treatments and/or breastfeeding alternatives which reduce efficaciously transmission require HIV testing, while vaginal disinfection and vitamin supplementation whom efficacy needs to be demonstrated do not. PREVENTION: Prevention of mother-to-child transmission and care of HIV+ adults in the area of opportunistic infections are feasible in Africa with an acceptable cost. This requires first to train and inform health care providers and the populations. Lots of uncertainties in these areas are likely to be alleviated by reinforcing clinical and therapeutic research of good quality including the questions of antiretroviral treatment. Ethical issues raised by the design and conduct of clinical research in Africa need a positive thinking to face the HIV African pandemic.     

Liver transplantation in HCV/HIV positive patients

Since the introduction of highly active antiretroviral therapy (HAART) in 1996 for human immunodeficiency virus (HIV)-infected patients, the incidence of liver diseases secondary to co-infection with hepatitis C has increased. Although data on the outcome of liver transplantation in HIV-infected recipients is limited, the overall results to date seem to be comparable to that in non-HIV-infected recipients. Liver transplant centers are now accepting HIV-infected individuals as organ recipients. Post-transplantation HIV replication is controlled by HAART. Hepatitis C re-infection of the liver graft, however, remains an important problem because cirrhotic changes of the liver graft may be more rapid in HIV-infected recipients. Interactions between the HAART components and immunosuppressive drugs influence drug metabolism and therefore meticulous monitoring of drug blood level concentrations is required. The risk of opportunistic infection in HIV-positive transplant patients seems to be similar to that in HIV-negative transplant recipients.     

Drug-resistant pulmonary tuberculosis in a cohort of southern African goldminers with a high prevalence of HIV infection.

OBJECTIVES: To determine rates of drug resistance to Mycobacterium tuberculosis and associated risk factors, including HIV infection. DESIGN: Prospective cohort study of patients with pulmonary tuberculosis. SETTING: The study population comprised 28,522 men working on four goldmines in Westonaria, Gauteng. Health care is provided at a 240-bed mine hospital, Gold Fields West Hospital, and its primary health care facilities. SUBJECTS: All 425 patients with culture-positive pulmonary tuberculosis identified in 1995. OUTCOME MEASURES: Tuberculosis drug resistance on enrollment and after 6 months' treatment. RESULTS: There were 292 cases of new tuberculosis, 77 of recurrent disease and 56 prevalent cases in treatment failure. Two hundred and seven patients (48.7%) were HIV infected. Primary resistance to one or more drugs (9%) was similar to the 11% found in a previous study done on goldminers in 1989. Primary multidrug resistance (0.3%) was also similar (0.8%). Acquired multidrug resistance was 18.1%: 6.5% for recurrent disease and 33.9% in treatment failure cases. Neither HIV infection nor the degree of immunosuppression as assessed by CD4+ lymphocyte counts was associated with drug resistance at the start or end of treatment. New patterns of drug resistance were present in 9 of 52 patients in treatment failure at 6 months, 1 of whom was HIV-infected. CONCLUSION: Primary and acquired drug resistance rates are stable in this population and are not affected by the high prevalence of HIV infection.     

Pathology of the breast associated with HIV/AIDS

Breast pathology that is characteristic of patients infected with human immunodeficiency virus (HIV) has not been addressed in the literature. HIV may directly and indirectly affect the glandular, mesenchymal, and intramammary lymphoid tissue in seropositive patients. Likely infections in this setting include tuberculous mastitis and pyogenic abscesses that may lead to fatal septicemia. Benign stromal changes include gynecomastia, adipose tissue deposition as part of the fat maldistribution syndrome, and pseudoangiomatous stromal hyperplasia. Breast carcinoma in HIV-infected patients occurs at a relatively early age, with increased bilateral disease, unusual histology, and early metastatic spread with a poor outcome. However, the link between breast cancer and HIV remains controversial. Kaposi's sarcoma and non-Hodgkin's lymphoma may also be localized to the breast in patients with acquired immunodeficiency syndrome (AIDS). This article reviews benign and malignant breast diseases that are likely to be encountered in patients with HIV/AIDS.     

Laparoscopic surgery for HIV-infected patients: minimizing dangers for all concerned.

As the number of patients infected with the human immunodeficiency virus (HIV) increases and their life-expectancy grows, more patients will present with conditions that require surgical intervention. Laparoscopic procedures provide several specific advantages over traditional (open) procedures in this population. For the patient, the extent of invasiveness is diminished; incisions are limited; healing time and wound complications can be decreased; pulmonary function is optimized; and the patient rapidly returns to regular activity. For the surgical team, risk of exposure to body fluids is minimized. For the general population, the exclusive use of readily available disposable instruments addresses infection control issues. Of 62 procedures performed on HIV-infected patients prior to the availability of laparoscopic surgery in the general surgery department, 27 (43.6%) could have been approached laparoscopically. Two patients with HIV infection are described who recently underwent successful laparoscopic procedures. In one case, this approach was the only option the patient would consent to. More widespread use of the approach should be specifically encouraged in patients with HIV infection.     

Bronchoalveolar lavage cell analysis in patients with human immunodeficiency virus related diseases

The value of differential cell counts in bronchoalveolar lavage fluid in patients who were serologically positive for the human immunodeficiency virus (HIV) was studied in 30 patients with classified into four groups according to the severity of illness: (1) seven subjects with the AIDS related complex without clinical or radiological evidence of pulmonary infection; (2) eight patients with the AIDS related complex and pulmonary tuberculosis; (3) eight patients with AIDS and Pneumocystis carinii pneumonia; and (4) seven patients with AIDS, Pneumocystis carinii pneumonia, and severe respiratory failure. All four groups had a similar percentage of lymphocytes, significantly higher than that of a control group of 15 healthy volunteers. A significant increase in the percentage of neutrophils was observed in groups 2, 3, and 4. The lavage fluid differential cell count does not therefore appear to help in the differential diagnosis of pulmonary infections in HIV positive patients. The abnormal percentage of lymphocytes observed in some patients with the AIDS related complex without clinical evidence of pulmonary infection suggests that lung injury may exist before clinical or radiological abnormalities develop. This might be related to an immunological mechanism or might be caused by an undetected subclinical infection.     

Effects of immunosuppressive drugs on HIV infection: implications for solid-organ transplantation

With the advent of highly active antiretroviral therapy (HAART), HIV infection has become a chronic disease. Various end-stage organ failures have now become common co-morbidities and are primary causes of mortality in HIV-infected patients. Solid-organ transplantation therefore has been proposed to these patients, as HIV infection is not anymore considered an absolute contraindication. The initial results of organ transplantation in HIV-infected patients are encouraging with no differences in patient and graft survival compared with non-HIV-infected patients. The use of immunosuppressive drug therapy in HIV-infected patients has so far not shown major detrimental effects, and some drugs in combination with HAART have even demonstrated possible beneficial effects for specific HIV settings. Nevertheless, organ transplantation in HIV-infected patients remains a complex intervention, and more studies will be required to clarify open questions such as long-term effects of drug interactions between antiretroviral and immunosuppressive drugs, outcome of recurrent HCV infection in HIV-infected patients, incidence of graft rejection, or long-term graft and patient survival. In this article, we first review the immunological pathogenesis of HIV infection and the rationale for using immunosuppression combined with HAART. We then discuss the most recent results of solid-organ transplantation in HIV-infected patients.     

Management of C virus infection in patients coinfected with HIV treated with antiretroviral agents

CONTEXT: The prevalence of hepatitis C virus (HCV) infection in patients infected by the human immunodeficiency virus (HIV) varies from 10 to 30%, depending on the mode of contamination, and reaches about 80% in intravenous drug users and hemophiliacs. The two viral infections can be treated simultaneously or, on the contrary, one may be given priority depending on the respective pathological or viral situations. MANAGEMENT OF COINFECTIONS: HCV infection does not appear to affect the natural course of HIV infection. Inversely, HIV infection aggravates HCV infection by amplifying HCV replication. This leads to a risk of more severe liver disease and a more rapid progression to cirrhosis. Mortality in HIV-infected patients is higher. This points to the importance of early diagnosis and treatment aimed at avoiding progression to potentially severe liver disease. The impact of highly effective anti-HIV tritherapy regimens, particularly restoration of immune competence, and of drug-induced hepatitis on the natural history of HCV infection should be taken into consideration when making management decisions concerning implementation of antiretroviral or anti-hepatitis C treatments. PERSPECTIVES: The long-term efficacy of alpha-interferon given in a single-drug regimen has been mediocre. New perspectives have appeared with the development of new treatments, particularly the ribavirin-alpha-interferon combination or the development of delayed-release alpha-interferon.     

Inguinal lymph node biopsy in patients infected with the human immunodeficiency virus is safe

BACKGROUND AND PURPOSE: The incidence of postoperative complications in human immunodeficiency virus (HIV)-infected patients remains controversial. Published data suggest that these patients are at higher risk for postoperative surgical site infections (SSIs) than are uninfected patients if the site is contaminated. To determine the incidence of postoperative SSI in HIV-infected patients undergoing aseptic surgery at uncontaminated sites, we performed a prospective case series analysis. We hypothesized that the rate of postoperative SSI would be low for this aseptic procedure, irrespective of CD4(+) lymphocyte counts. Additionally, we monitored the rates of other complications, namely, hematoma, dorsal vein thrombosis, epididymitis, lymphocele, and suture extrusion. METHODS: From May 1, 2000, through January 31, 2006, we performed 137 sterile inguinal lymph node biopsies in 44 HIV-infected patients as part of a funded study evaluating the role of peripheral lymphatic tissue in the pathophysiology of HIV infection. Postoperatively, we followed all patients for a minimum of 30 days. RESULTS: Postoperatively, we noted one instance each (0.7%) of infection, dorsal vein thrombosis with epididymitis (0.7%), and lymphocele and two cases each (1.4%) of hematoma and suture extrusion. The CD4(+) count at the time of biopsy did not correlate with postoperative complications. CONCLUSIONS: Inguinal lymph node biopsy in HIV-infected patients is safe, irrespective of CD4(+) lymphocyte count.     

Disseminated kidney tuberculosis complicating autosomal dominant polycystic kidney disease: a case report

Mycobacterium tuberculosis infection in patients with autosomal dominant polycystic kidney disease (ADPKD) is rare, and its diagnosis and treatment are difficult because numerous cysts are exposed to infection and antibiotics do not easily penetrate infected cysts. Here, we report the case of a 43-year-old Japanese man with disseminated urogenital tuberculosis (TB) and ADPKD without human immunodeficiency virus (HIV) infection. Delayed diagnosis and ineffective anti-TB chemotherapy worsened his condition. Finally, he underwent bilateral nephrectomy but experienced postoperative complications. In conclusion, kidney TB should be recognized as a cause of renal infection in ADPKD, and surgical treatment should be instituted without delay. The importance of early diagnosis and treatment cannot be overemphasized to prevent kidney TB deterioration.     

Pulmonary Mycobacterium kansasii infection: comparison of radiological appearances with pulmonary tuberculosis.

BACKGROUND: A study was undertaken to determine if there are differences in the radiological appearances at presentation between pulmonary infections caused by Mycobacterium kansasii and Mycobacterium tuberculosis. Correct recognition of the organism has important implications with regard to initial therapy and contact tracing. METHODS: The initial chest radiographs of 28 patients with pulmonary M kansasii infection were compared with those of 56 age, sex, and race matched patients with M tuberculosis infection. All patients in both groups were culture positive and none was known to be HIV positive. The radiographs were analysed independently by two radiologists who were unaware of the causative organism. RESULTS: Radiographic abnormalities in patients with M kansasii infection were more frequently unilateral and right side predominant, while those with tuberculosis more frequently involved a lower lobe. Air space shadowing involving more than one bronchopulmonary segment and pleural effusions were seen less frequently in M kansasii infection (four of 28 (14%) versus 30 of 56 (54%) and none of 28 versus 15 of 56 (27%)). Cavitation (21 of 28 (75%) versus 34 of 56 (61%) was seen to a similar extent in patients with M kansasii infection and in those with tuberculosis. Cavities tended to be smaller in patients with M kansasii infection (p < 0.01). CONCLUSIONS: Differences are seen in the radiographic appearances of pulmonary infection caused by M kansasii and M tuberculosis. These differences are not sufficient to allow a positive diagnosis on the basis of radiographic findings alone, but the presence of a pleural effusion or lower lobe involvement makes M kansasii infection very unlikely.