Association of contaminated gloves with transmission of Acinetobacter calcoaceticus var. anitratus in an intensive care unit

PURPOSE: Acinetobacter calcoaceticus var. anitratus is an important nosocomial pathogen that has been associated with environmental reservoirs. An increased isolation rate of A. anitratus in our intensive care units (ICUs), from 0.03% (two of 7,800) to 0.5% (seven of 1,300) (p less than 0.00003), prompted an investigation. PATIENTS, METHODS, AND RESULTS: Ten patients were admitted to the surgical ICU and nine to the medical ICU during the outbreak period (late December 1987 to January 1988). Controls were all patients on the units who were not infected or colonized with the transmitted strain of A. anitratus. Three patients had A. anitratus pneumonia. A throat culture prevalence survey demonstrated three patients colonized with A. anitratus. Cases were placed in a cohort and symptomatic cases treated. An epidemiologic investigation was conducted to identify reservoirs and modes of transmission. Latex gloves were being used for universal precautions without routine changing of gloves between patients. Environmental sources culture-positive for A. antitratus included a small volume medication nebulizer and gloves in use for patient care. Plasmid typing showed that plasmid profiles of isolates from two symptomatic patients, two colonized patients, the nebulizer, and the gloves were identical. Other A. anitratus ICU isolates had distinct plasmid profiles. All patients with the transmitted strain had been in the surgical ICU. The need for changing gloves between patients and contaminated body sites was reinforced. CONCLUSION: Gloves, used incorrectly for universal precautions, may potentially transmit A. anitratus.     

Acinetobacter Anitratus Infections in Man

Summary: Acinetobacter anitratus infections in man. M. L Thong, Aust. N.Z. J. Med. , 1975, 5 , pp. 435–439.
During a period of 17 months, 142 strains of Acinetobacter anitratus were isolated from 140 patients. They were examined for biochemical characteristics, antibiotic susceptibilities to 15 chemotherapeutic drugs and clinical and epidemiologic features. Biochemical studies were necessary for positive identification of this gram negative rod. Many isolates were susceptible to kanamycin, gentamicin, polymixin B, cotrimoxazole and nalidixic acid. Most isolates were hospital acquired and had been cultured from a number of anatomic sites in the presence of a variety of clinical situations. Acinetobacter anitratus was the primary infecting organism in two cases of septicaemia (one fatal), two pneumonias, two wound infections and six urinary tract infections. Because of its potential pathogenicity this organism should not be dismissed as a harmless commensal by laboratory staff and clinicians.     

Clinical studies on lung disease due to atypical mycobacteria in our hospital during the past 13 years

Among the patients with pulmonary diseases admitted to our hospital during a 13-year period from 1977 to 1989, clinical examinations and laboratory data on admission and the following clinical courses of 102 cases where atypical mycobacteria had been identified three times or more in sputum cultures at the time of hospitalization were investigated. 1. The ratio of the number of cases positive for atypical mycobacteria to those positive for acidfast bacilli in sputum cultures tested on admission was fairly constant, 6.0 to 7.8% every year since 1981. In the cases associated with positive sputum cultures for atypical mycobacteria, M. avium complex was observed in 84% of the cases: M. kansasii, M. fortuitum and M. chelonae were found in 13, 2 and 1 cases, respectively, since 1984. 2. A total of 102 cases studied consisted of 66 male and 36 female patients; the mean age was 61.9 years. 3. Sputa became negative on culture in 19 (86.4%) out of 22 cases of primary infection. In all primary infection cases, roentgenographic findings did not worsen and prognosis was extremely good. In secondary infection cases, sputum cultures became negative in 25 (83.3%) out of 30 cases expectorating a small quantity of mycobacteria on admission, where x-ray findings worsened in only one case. In contrast, in 47 cases expectorating a large quantity of the bacilli at the time of admission, negative sputum cultures were attained in only 14 cases (29.8%) and x-ray findings worsened in 10 cases, and their prognosis were poor. 4. In general, sputum cultures turned negative within 3 months after admission. If sputum cultures remained positive thereafter, it was found very difficult to stop expectoration of the bacilli in these patients, and hence their prognosis are supposed to be greatly affected by the bacteriologic findings in early stages of the disease.     

An outbreak of Burkholderia cepacia associated with contamination of albuterol and nasal spray

BACKGROUND: Species within the Burkholderia cepacia complex (Bcc) can contaminate medications and disinfectants and cause severe pneumonia in critically ill patients or persons with cystic fibrosis. In March 2004, we investigated a hospital outbreak of Bcc possibly associated with a contaminated nasal spray. METHODS: We conducted a matched case-control study, environmental sampling, and observations of infection control practices. Case patients had infection or colonization with Bcc, and control patients had sputum culture not yielding Bcc. Isolates from patients and environmental samples were compared by pulsed-field gel electrophoresis (PFGE). RESULTS: Bcc was recovered from sputum in 18 patients. Compared with matched control patients (n = 18), case patients were more likely to be receiving mechanical ventilation (p = 0.01), to have been hospitalized > 6 days (p = 0.01), and to have received antimicrobial treatment within 7 days before sputum collection (p = 0.03). Bcc was cultured from opened, but not unopened, multidose albuterol bottles, a nebulizer attached to a ventilator, and opened and unopened nasal spray bottles from contaminated lots. PFGE showed that isolates from albuterol samples and from patients were indistinguishable but unrelated to the nasal spray strain. Observations revealed improper aseptic techniques during respiratory therapy procedures and inadequate nebulizer cleaning. CONCLUSIONS: Despite a temporal association with use of a contaminated nasal spray, this outbreak was caused by extrinsic contamination of multidose albuterol used for nebulization treatments and lack of adherence to infection control precautions. Implementation and re-enforcement of infection control measures successfully terminated the outbreak.     

A nosocomial outbreak of ampicillin-resistant Haemophilus influenzae type b in a geriatric unit

A nosocomial outbreak of Haemophilus influenzae type b (Hib) bronchitis occurred in a geriatric unit. The three infected patients were grouped together in an isolation unit and treated. A prevalence survey was done by obtaining pharyngeal cultures from patients and staff in the unit. One patient and a nurse were asymptomatic pharyngeal carriers of Hib. One infected patient was bedridden, and his only known Hib contact was the nurse. Geographic clustering was the only significant risk factor, as determined by a case-control study. Carriers were treated with rifampin. The isolates were characterized for strain relatedness by using three methods. All produced beta-lactamase and all were serotype b. Plasmid profiles and restriction endonuclease analysis of bacterial DNA were performed; chromosomes were digested with the restriction endonucleases HindIII and HaeIII. Strains were confirmed as identical by using these methods and were different from two Hib control strains producing beta-lactamase. This study documents nosocomial transmission of Hib, by using molecular typing methods.     

Rapid control of an outbreak of Staphylococcus aureus on a neonatal intensive care department using standard infection control practices and nasal mupirocin

BACKGROUND: Staphylococcus aureus is a common pathogen in neonatal intensive care departments, causing significant morbidity, mortality, and cost. Frequently, S aureus outbreaks may last for months or years. After a cluster of 4 clinically significant S aureus infections in a 7-day period in our 35-bed neonatal intensive care department, we immediately introduced standard outbreak control measures. Unique to our approach was the addition of immediate nasal mupirocin treatment of all staff members and selected patients. METHODS: Patients were screened for S aureus colonization and were cohorted with separate caregivers. S aureus isolates were submitted to a reference laboratory for pulse-field gel electrophoretic typing. Infection control practices were emphasized and education was provided for staff, physicians, and parents of patients. All caregivers and selected patients were treated immediately with nasal mupirocin. Cohorting was maintained until all patients who were colonized or infected were discharged. RESULTS: A total of 5 patients were found to be infected and 4 of 19 patients tested were found to be colonized during the study period. Patients who were infected were successfully treated. Secondary colonization and infection did not occur after implementation of controls. CONCLUSIONS: Rapid and comprehensive implementation of standard outbreak controls along with immediate treatment of direct care staff and patients with nasal mupirocin successfully controlled this outbreak within 4 weeks and no further cases have been noted.     

Hepatitis-associated-antigen-positive hepatitis in a tuberculosis unit.

An outbreak of hepatitis-associated-antigen-(HB Ag)-positive hepatitis in a hospital unit for the care of male patients with pulmonary tuberculosis is described. Sixty-four patients were studied of whom 37 were HB Ag positive. Hepatitis developed in at least 20 and was icteric in 11. The illness was mild, without fatality due to hepatitis and persistent jaundice did not occur. A carrier state developed in 15 of 24 HB Ag-positive patients followed up for more than six months and was unrelated to the presence or absence of initial hepatitis. Spread of HB Ag to domestic and medical staff occurred and following the discharge of the patients, household contacts became positive. Five, all wives of patients, developed jaundice. Faeces and sputum were HB Ag negative in seropositive cases. The origin of the outbreak remains undetected. The probability of non-parenteral transmission of HB Ag in this outbreak is discussed. Closure of the unit, isolation of HB Ag-positive cases with separate toilet and kitchen facilities, and discharge of patients when their respiratory condition allowed, resulted in prevention of further spread and eventually all patients were discharged from the unit.     

Severe community-acquired pneumonia due to Acinetobacter baumannii

STUDY OBJECTIVES: To investigate the clinical, epidemiologic, and microbiological characteristics of community-acquired pneumonia (CAP) due to Acinetobacter baumannii. METHODS: Retrospective chart and radiographic reviews of all patients who were admitted to National Taiwan University Hospital from January 1993 to August 1999, fulfilled the criteria for CAP, and had an isolate of A. baumannii from blood or pleural fluid at hospital admission. RESULTS: Thirteen patients (9 men and 4 women; age range, 37 to 85 years) met the criteria. Conditions associated with the infection included male gender, old age, alcoholism, malignancy, cerebrovascular disease, diabetes mellitus, renal disease, and liver cirrhosis. Eleven patients (85%) acquired the infection during the warmer months of April to October. Twelve patients (92%) had a fulminant course presenting with septic shock and respiratory failure, and 11 patients (85%) needed ventilator support and were treated in an ICU. Six patients (46%) had leukopenia. Lobar consolidations were found in 12 patients (92%), and pleural effusions were present in 4 patients (31%). All patients had positive blood culture results, two patients (15%) had positive pleural effusion culture findings, and nine patients (69%) positive sputum culture results. All the isolates were susceptible to imipenem, and most were susceptible to aminoglycosides, ceftazidime, ciprofloxacin, and extended-spectrum penicillins. Eight patients (62%) died. Four of the five survivors were initially treated with combination of a third-generation cephalosporin and an aminoglycoside. CONCLUSION: A. baumannii should be considered as a possible etiologic agent in community-acquired lobar pneumonia when (1) patients with a fulminant course present during the warmer and more humid months of the year, and (2) patients are younger alcoholics. A good sputum smear, defined as a Gram stain smear of an adequate sputum specimen that comes from the lower respiratory tract and contains > 25 leukocytes per high-power (100x) field on microscopic examination, can help early diagnosis and treatment. A combination of a third-generation cephalosporin and an aminoglycoside may be appropriate empirical therapy.     

A common-source outbreak of fulminant hepatitis B in a hospital

A nosocomial outbreak of fulminant hepatitis B infection at a medical center in Haifa, Israel, between 7 and 26 June 1986, involved five patients who had been hospitalized previously in the medical ward in late April and early May (first generation). This outbreak had an unusual clinical course, with fulminant hepatic failure associated with acute renal failure from acute glomerulonephritis, leading to death within a few days. The onset dates of hepatitis were tightly clustered temporally and incubation periods were short. Extensive laboratory and epidemiologic evaluation showed that the probable common-source vehicle of transmission was a multiple-dose vial of heparin and normal saline flush solution that may have been contaminated by blood of a known HBsAg carrier, who was positive for anti-HBe, hospitalized at the same time. A sixth patient died in August 1986 (second generation), after his initial admission in June that coincided with the terminal hospitalizations of three first-generation patients. Those patients had marked coagulopathies, and transmission to the sixth patient most probably occurred through environmental contamination by patients or through cross-contamination between patients through staff. The unusually high mortality rate (5 of 6) in this outbreak has not been definitely explained.     

Nosocomial clonal dissemination of methicillin-resistant Staphylococcus aureus. Elucidation by plasmid analysis

An outbreak of methicillin sodium-resistant Staphylococcus aureus (MRSA) infection and colonization, mainly centered in the vascular surgery service, occurred in a 1000-bed tertiary care center between December 1983 and December 1984. Methicillin-resistant S aureus isolated before and during the outbreak was studied by both bacteriophage typing and by restriction endonuclease digestion of bacterial plasmid DNA. Bacteriophage typing was discrepant in nine (56%) of the 17 repeated analyses compared with one (3.4%) of the 29 for plasmid profiling. These typing methods revealed that the epidemic strain was introduced to the hospital from the community 15 months before the outbreak. The outbreak was caused by cross-transmission of the epidemic strain by health care personnel and was controlled by treatment of colonized personnel, education of personnel, and institution of barrier precautions for colonized or infected patients. Plasmid profiling with restriction endonuclease digestion was easier, more rapid, and more specific than bacteriophage typing in the evaluation of this outbreak.     

Legionella pneumonia due to exposure to 24-hour bath water contaminated by Legionella pneumophila serogroup-5

A 79-year-old man was admitted to hospital from his nursing home for treatment of pneumonia, but died 7 days after admission. Legionella pneumonia was diagnosed after isolation of Legionella pneumophila serogroup-5 from sputum culture. The environment of the nursing home was investigated; only water specimens from the 24-hour bath were positive by culture for Legionella pneumophila serogroup-5. Subsequent analysis by pulsed-field gel electrophoresis revealed an identical pattern in isolates from both sputum culture and 24 hour bath water culture. Among 123 inpatients and staff of the nursing home, 17 were found to be seropositive for Legionella pneumophila serogroup-5.     

A large outbreak of Legionnaires' disease due to an inadequate circulating and filtration system for bath water--epidemiologic manifestations

OBJECTIVE: To study the epidemiologic manifestations of a large outbreak of Legionnaires' disease due to an inadequate circulating and filtration system for bath water. PATIENTS: In June 2000 at Ishioka City, Ibaraki Prefecture, a large outbreak of Legionnaire's disease occurred, as a result of an inadequate circulating and filtration system for communal bath water. This outbreak was the worst ever experienced in Japan, involving a total of 34 patients (20 confirmed, 14 probable), 3 of whom died. MEASUREMENTS AND RESULTS: Legionella pneumophila serogroup 1 was isolated from sputum culture in two patients. Bacteriological culture of the public bath water subsequently yielded large numbers of Legionella species. Cleavage of genomic DNA showed that restriction fragment patterns coming from clinical and environmental isolates of L. pneumophila serogroup 1 were closely related, focusing the inquiry to a public bathhouse where a circulating filtration system was suspected as the source of infection. CONCLUSIONS: It was later concluded that the circulating filtration system adopted for bath water was marred by a serious design flaw that subsequently caused the mass outbreak. Specifically, a line of the bath water was being returned to the bath without undergoing heat exchange or sterilization by chlorine; and the Legionella species that had proliferated in the filter and the bright stone filtration unit were allowed to return to the bath, eventually culminating in a mass infection.     

补习学校肺结核暴发的特征及原因调查

目的 2013年4-7月某高考补习学校多名学生陆续被诊断为活动性肺结核。方法采用肺结核可疑症状调查、胸部影像学、结核菌素(PPD)试验、痰涂片检查等对全体师生和被诊断学生的家庭密切接触者进行筛查;收集病例的社会人口学资料进行横断面分析。结果首例患者发病后约2个月才明确诊断,随后该班级45人中有10名学生先后被诊断为活动性肺结核,罹患率22.2%。肺结核病例除与首发病例有密切接触之外,与性别、年龄、户籍等无明显关联。结论这是一起典型的学校班级内感染的结核病暴发,具有发病水平较高、季节性和聚集性等特征。本次暴发原因主要是学校结核病防控意识欠缺、综合医疗机构迟报、漏报、转诊不及时等因素共同造成的。     

入住 EICU 的高龄重症肺炎患者院内死亡的危险因素分析

目的：研究影响入住急诊重症监护室(EICU)的高龄(>65岁)重症肺炎患者院内死亡的危险因素。方法回顾性纳入2015年1月1日至5月31日因重症肺炎入住我院 EICU 的高龄患者,统计其院内病死率,同时收集相关临床资料,对病死率产生影响的因素进行分析。结果共纳入了30例重症肺炎患者,平均年龄(81.77±7.78)岁,其中男性19例,平均年龄(79.53±7.25)岁。死亡12人,其中男性8例,平均年龄(81.17±10.20)岁。患者性别、是否全身应用糖皮质激素、近3个月内是否住院治疗以及是否应用机械通气、气管镜治疗、急性生理与慢性健康评分(APACHE Ⅱ评分)与死亡无关,入院时动脉血气分析(ABG)中血乳酸水平以及入院时呼吸频率与院内病死率相关,进一步的多因素分析提示上述指标均不是重症肺炎患者 EICU 院内死亡的独立危险因素。结论动脉血乳酸水平以及入院时呼吸频率与入住 EICU 的重症肺炎患者院内死亡有关,但不是其独立危险因素。     

An outbreak of Serratia marcescens in 14 adult cardiac surgical patients associated with 12-lead electrocardiogram bulbs.

Two clusters of Serratia marcescens in 14 adult cardiac surgical patients occurred over 10 months in an 876-bed teaching hospital. The 14 infections that were studied were as follows: one sternal and five leg incisions, five pneumonias, one bacteremia, one urinary tract infection, and one infected internal defibrillator site. The first cluster included four pneumonias, one urinary tract infection, and one bacteremia. Corrective actions were taken based on outbreak data through no source was identified. No further infections occurred during the following 2 months. The second cluster included one sternal and five leg incisions, an infected internal defibrillator incision site, and one pneumonia. Serratia marcescens was isolated from six electrocardiogram rubber welsh bulbs with sensitivities identical to patient isolates that indicated a common source outbreak in at least the second cluster of infections. Disposable electrocardiogram leads were introduced and the problem was resolved. We conclude that reusable electrocardiogram welsh bulbs are a vector for postoperative infections.     

监护室分离的鲍曼不动杆菌的耐药特征与同源性分析

目的 探讨ICU中鲍曼不动杆菌感染暴发的原因、耐药特征及其同源性,分析其可能的传播途径,为治疗和预防鲍曼不动杆菌院内感染提供依据.方法 收集解放军总医院某ICU2007年5-6月份收治的鲍曼不动杆菌感染患者的痰、血液、尿及创口分泌物等临床标本,同时采集同期医护人员手、呼吸机管路、患者皮肤和病床等部位的环境标本进行细菌培养、分离及鉴定;应用琼脂稀释法测定鉴定为鲍曼不动杆菌标本的MIC值,分析其耐药特征,并用脉冲场凝胶电泳进行分型,判断其同源性.结果 分离到的12株鲍曼不动杆菌对亚胺培南和美罗培南的耐药率达100%,对替加环素的敏感度为91.7%,对多黏菌素均敏感.12株菌株经脉冲场凝胶电泳分为A、B、C 3个类型,在医护人员手上分离到的鲍曼不动杆菌与患者体液中分离到的鲍曼不动杆菌同型.在1个月内,A型和B型菌株对米诺环素的药敏试验结果由中介变为耐药,A型菌株中出现1株替加环素耐药菌株.结论 ICU中出现的鲍曼不动杆菌为碳青霉烯类耐药的鲍曼不动杆菌,其耐药性在1个月内发生了改变.带有致病菌的医护人员的手可能为ICU中鲍曼不动杆菌感染的媒介.     

Plasmid mediated antibiotic resistance of Vibrio cholerae O1 biotype El Tor serotype Ogawa associated with an outbreak in Kolkata,India

ObjectiveTo determine the antibiotic resistance of Vibrio cholerae (V. cholerae) O1 biotype El Tor serotype Ogawa isolates involved in an outbreak of watery diarrhea in Kolkata, and to explore the role of plasmid in mediating antibiotic resistance.MethodsAntibiotic susceptibility and minimum inhibitory concentration (MIC) values of antibiotics for the isolated V. cholerae O1 Ogawa (n=12) were determined by disk diffusion and agar dilution methods, respectively, using ampicillin (Am), chloramphenicol (C), trimethoprim (Tm), tetracycline (T), erythromycine (Er), nalidixic acid (Nx), ciprofloxacin (Cp), amikacin (Ak) and cefotaxime (Cf). Plasmid curing of multidrug resistant (MDR) V. cholerae O1 Ogawa strains was done following ethidium bromide treatment. Following electrophoresis, the plasmid DNAs, extracted from the isolated MDR V. cholerae O1 Ogawa strains and their cured derivatives, were visualized and documented in ‘gel doc’ system.ResultsThe outbreak causing V. cholerae O1 Ogawa isolates were MDR as determined by disk diffusion susceptibility test, and MIC determination. The isolates showed three different drug resistance patterns: AmTmTErNx (for 6 isolates), TmTErCp (for 5 isolates), and AmTmNx (for one isolate), and showed uniform sensitivity to C, Ak and Cf. The loss of plasmids with the concomitant loss of resistance to Am, Tm, T and Er of the isolates occurred following ethidium bromide treatment.ConclusionsThe current findings suggest that the V. cholerae O1 Ogawa associated with the cholera outbreak were MDR, and resistance to Am, Tm, T and Er among the isolates were plasmid mediated.     

Outbreak of tuberculosis in a homeless population involving multiple sites of transmission.

SETTING: During 2002-2003, a large outbreak of tuberculosis (TB) occurred among persons using multiple homeless facilities in King County, Washington. OBJECTIVE: To control the transmission of TB in multiple settings. DESIGN: In 2002, contacts exposed to patients in homeless facilities were screened using tuberculin skin tests (TSTs) and symptom review. Based on these screening results, sites of transmission were identified and prioritised, and exposed cohorts at these sites were offered intensive screening tests in 2003 (e.g., symptom review, TST, chest radiograph [CXR], sputum examination and culture). Mycobacterium tuberculosis isolates from patients were genotyped using PCR-based methods to identify outbreak-associated patients quickly. RESULTS: During 2002-2003, 48 (15%) of 313 patients diagnosed in King County were outbreak-associated; 47 culture-positive patients had isolates that matched the outbreak strain by genotyping. Three facilities visited by >12 patients in 2002 had a higher prevalence of TST positive results (approximately 30%) among clients compared with the background rate (7%) in the homeless community. Screening contacts with one sputum culture was as sensitive as CXR in detecting TB disease (77% vs. 62%, respectively). CONCLUSIONS: A comprehensive, resource-intensive approach likely helped to control transmission. This outbreak highlights the vulnerability of homeless populations and the need to maintain robust TB programs in urban settings.     

An outbreak of Legionella micdadei pneumonia in transplant patients: evaluation, molecular epidemiology, and control

PURPOSE: To describe a nosocomial outbreak of Legionella micdadei pneumonia in transplant patients and to characterize the source of the outbreak and the control measures utilized. SUBJECTS AND METHODS: We performed retrospective Legionella micdadei serologic testing to enhance case finding in transplant patients with pneumonia that lacked a documented microbial etiology, as well as prospective environmental surveillance of water sites and testing for Legionella in clinical specimens. RESULTS: During a 3-month period, 12 cases of Legionella micdadei pneumonia were identified either by culture or serologic testing among 38 renal and cardiac transplant patients. Legionella micdadei isolates from hot water sources were found by pulsed-field gel electrophoresis to have a DNA banding pattern that was identical to the isolates from the first 3 culture-positive cases and from 2 cases that occurred 16 months later. CONCLUSIONS: Hospitals caring for organ transplant recipients and other immunosuppressed patients must be aware of the possibility of environmental sources of outbreaks of Legionella infection. A first-line screen with the Legionella urine antigen test will identify Legionella pneumophila serogroup 1. However, specific cultures in outbreak situations should be considered to identify other Legionella pneumophila serotypes and the nonpneumophila Legionella species.     

Adjunctive salvage therapy with inhaled aminoglycosides for patients with persistent smear-positive pulmonary tuberculosis.

A proportion of patients with drug-resistant and drug-susceptible tuberculosis (TB) have sputum that is smear and culture positive for Mycobacterium tuberculosis for a prolonged period of time, despite conventional therapy. Among such patients with refractory TB, an unblinded, observational study was undertaken that used conventional TB therapy and adjunctive aerosol aminoglycosides. Patients with persistent smear- and culture-positive sputum for M. tuberculosis (despite > or =2 months of optimal systemic therapy) were selected for adjunctive treatment via inhalation with aminoglycosides, and microbiological responses were monitored. Thirteen of 19 patients converted to smear negativity during the study: 6 of 7 with drug-susceptible TB and 7 of 12 with drug-resistant TB. Among patients with drug-susceptible TB, the median time to sputum conversion was 23 days, a shorter time than for a population of historical control patients. Recurrent infection was not observed. Adjunctive aerosol aminoglycosides may expedite sterilization of sputum among certain patients with refractory TB and diminish the risk of transmission.