Stella Sala Soares Lima

Métodos convencionais e moleculares para o diagnóstico da tuberculose pulmonar: um estudo comparativo

OBJECTIVE: To compare four laboratory methods in the diagnosis of pulmonary tuberculosis. METHODS: Respiratory secretion specimens were collected from 160 patients suspected of having pulmonary tuberculosis. Direct testing for Mycobacterium tuberculosis was carried out using Ziehl-Neelsen and auramine staining. In addition, culture in Lowenstein-Jensen (LJ) medium and polymerase chain reaction (PCR) were used. The strains isolated were identified by means of a radiometric method using p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) and classical methods. The sensitivity of the methods was compared to the gold standard for the diagnosis of pulmonary tuberculosis, based on clinical, radiological and microbiological criteria. RESULTS: Of the 160 patients, 142 were diagnosed with pulmonary tuberculosis according to the gold standard. The sensitivity of Ziehl-Neelsen staining, auramine staining, culture in LJ medium and PCR was 54.2%, 58.4%, 67.6% and 77.5%, respectively, when compared with the diagnostic criterion adopted. All four methods presented 100% specificity. In the identification of mycobacteria, there was high (96.8%) concordance between PCR and the radiometric method using NAP. The sensitivity of PCR was 50.8% in samples with negative sputum smear microscopy results and 98.8% in those with positive results. The sensitivity of PCR was lower in specimens with negative results in sputum smear microscopy and culture than in those with positive results (25.6% and 99.0%, respectively). CONCLUSIONS: We found PCR to be a promising method for the diagnosis of pulmonary tuberculosis, even in paucibacillary specimens. Simultaneous identification and faster results are additional advantages of this method.

Tuberculosis in liver transplant recipients: a single Brazilian center experience.

Background. Tuberculosis (TB) is an important opportunistic infection in transplant recipients worldwide. The frequency of Mycobacterium tuberculosis disease varies among different regions, but the incidence of TB in adult liver transplant (LT) recipients is largely unknown. The estimated frequency ranges from 0.7% to 2.3%, with mortality rate up to 30%. However, these data are based on individual case reports or series with small samples. In LT recipients, therapy is generally associated with significant hepatotoxicity and interactions with immunosuppressive drugs. Methods. This retrospective analysis included 319 patients who underwent LT at University Hospital, Federal University of Minas Gerais, Brazil, between September 1994 and July 2007 and survived more than 1 month. Among these, TB was diagnosed in five patients. No patients received chemoprophylaxis before or after LT. Results. All five patients were women, mean age 39.6±16.5 years. Two patients had disseminated TB, two pulmonary involvement, and one extrapulmonary disease. Cultures were positive in four patients. Overall, four patients received isoniazid, rifampin, and pyrazinamide for 6 to 12 months, with good tolerance, but one patient presented recurrence. Another patient presented raised hepatic enzymes levels after initiating therapy. All patients are alive and well. Conclusions. In this series, the TB frequency after liver transplantation was 1.57%, with no confirmed hepatotoxicity with conventional treatment and an excellent survival rate (100%).

Visceral leishmaniasis in liver transplant recipients from an endemic area.

Visceral leishmaniasis (VL) is a parasitic infection generally caused by the Leishmania donovani complex, and in Brazil by Leishmania chagasi. Every year, half a million new cases are diagnosed worldwide, and five countries— Nepal, Bangladesh, Brazil, India, and Sudan—account for up to 90% of cases (1, 2). Although considered a rare disease among transplant recipients, the number of reported cases has increased over the last two decades (3). VL diagnosis should also be considered in transplant recipients from nonendemic areas, in view of increasing migration and the globalized world. We report three cases of VL in liver transplantation (LT) recipients in a single center from Brazil. Hospital records of 595 patients who underwent LT from September 1994 to December 2009 at the Federal University Hospital of Minas Gerais, Brazil, were reviewed. Three of the 595 liver transplanted patients were diagnosed with VL. Their detailed clinical characteristics are shown in Table 1. A case is defined as the presence of Leishmania amastigotes in bone marrow aspirate or specimens of other reticuloendothelial system organs in patients with symptoms consistent with VL. The typical clinical picture is characterized by fever, splenomegaly, weight loss, blood cytopenia, and hypergammaglobulinemia (2, 4). All patients presented with fatigue, pancytopenia, and hypergammaglobulinemia, and two patients had fever and splenomegaly. Diagnosis was established by the presence of Leishmania amastigotes in bone marrow aspirate (Fig. 1) in all cases. Initial therapy was amphotericin B deoxycholate, which caused nephrotoxicity in all three patients and was replaced by liposomal amphotericin B. Immunosuppression was reduced once the VL diagnosis was established, and maintained at the lowest possible level for a few months. Two patients are alive and free of disease. The other patient is alive but experienced a VL relapse; he was retreated with liposomal amphotericin B and has continued on monthly secondary prophylaxis (3 mg/kg/monthly). VL infection in transplant recipients may occur in four ways: (1) the recipient may be infected by the graft; (2) by transfusion; (3) a previously infected recipient may reactivate a latent infection; and (4) immunosuppressed patients may develop de novo infections (3, 5). Because specific antibody responses are not protective (6), suppression of the T-cell host response after organ transplantation may reactivate a latent VL infection. In the present series, it was not possible to identify the way of transmission. The rising number of transplants, including in VL-endemic regions, justifies the increasing interest in such a neglected disease. Timely diagnosis followed by prompt treatment can have an impact on the high lethality rates (3). Until now, only 10 cases of VL in LT recipients have been described, one of them by our group (7–14). Cases are probably underestimated by misdiagnosis. Given that the liver is a reticuloendothelial organ preferentially affected by the protozoan, the risk of transmission through the graft may be greater than in other transplants. Transplanted patients should benefit from lipid formulations as of the beginning of treatment, because immunosuppressive drugs are also nephrotoxic and renal dysfunction is frequent. Cure is generally defined by clinical and hematological criteria (resolution of fever, hepatosplenomegaly, and pancitopenia). Follow-up is recommended for 6 months after treatment (15, 16). Although some authors also consider negative bone marrow biopsies or aspirate cultures after treatment (17), these are invasive procedures and absence of parasites does not define resolution or exclude relapse (18). VL cure rates after amphotericin treatment in transplanted patients are approximately 80%. However, relapse may occur in up to 35% of the cases, associated to poor prognosis (13). One described patient, despite adequate treatment, presented a relapse 5 months after amphotericin discontinuation. He was then retreated and remains on secondary prophylaxis with monthly liposomal amphotericin. Some studies have shown that secondary prophylaxis may prevent a VL relapse, but they were carried out in HIV patients (18, 19). The evidence of this recommendation in transplanted patients is not yet established, but it should be considered in those who relapse. Asymptomatic infection (from donors or recipients) in the pretransplant phase could facilitate the suspicion of VL after LT in the presence of certain symptoms (19). We do not perform VL serology routinely for screening liver donors and recipients before transplant, but this is the matter of an ongoing research project. At present, if recipients or donors have a positive result, we perform a stricter follow-up with a lower threshold of suspicion for VL. In conclusion, VL is a potential infectious complication in liver transplanted patients, mainly in endemic areas, and probably remains underestimated and underdiagnosed in these patients. Prompt diagnosis and treatment are essential to reduce lethality.

Phenotypic and genotypic characterization of drug-resistant Mycobacterium tuberculosis strains.

Of 142 pulmonary tuberculosis patients, 76 were considered high risk for the development of resistance, and 24 were confirmed as resistant strain carriers. Resistant isoniazid strains presented a high frequency of katG and ahpC mutations (90%) correlated with an MIC >4 microg/mL (94%). inhA mutations were not seen. rpoB mutations were identified in 78.6% of rifampicin-resistant strains, usually in codon 531 (72.7%), and 75% had an MIC >16 microg/mL. katG and rpoB mutations recognized 88.2% of multidrug-resistant strains and proved more efficient than the katG and rpoB mutations alone. Seventy percent of resistant pyrazinamide strains had pncA mutations between genes 136 and 188, 62.5% of them with an MIC >900 microg/mL. Pyrazinamidase inactivity was not an efficient resistance marker because 60% of pncA-mutated strains maintained enzymatic activity despite displaying good correlation with high resistance levels. Resistant ethambutol strains had embB mutations in codon 306, with MIC >16 microg/mL.

MRSA outbreak at a transplantation unit

Methicillin-resistant Staphylococcus aureus (MRSA) infections frequently complicate the post-operative course of transplant recipients, and despite nasal carriage and endemic colonization, MRSA outbreaks are not commonly described. This study reports a case of MRSA outbreak and discusses infection control measures and recommendations for this situation.

Neutropenic patients and their infectious complications at a University Hospital

Objective The aim of this study was to analyze the characteristics and infectious complications of neutropenic patients in a referral hospital. Methods A cross-sectional study was carried out between April and September 2008, which enrolled all neutropenic patients identified by daily blood counts in the Universidade Federal de Minas Gerais. Demographic data and information on infections were obtained from the Hospital Infection Control Committee. Statistical analysis was performed using the Statistical Package for Social Sciences. Results One hundred and sixteen patients were followed up during 129 hospitalizations. The patients had a mean age of 48.7 years old. Sixty-four (55.2%) patients were male and 25 (21.6%) died during the follow-up. In 97 (75.2%) of the hospitalizations, patients had episodes of febrile neutropenia. Patients classified as low-risk had a mortality rate of 16.2% (n = 12) vs. 39.1% (n = 9) among high-risk patients (p-value = 0.02). The death rate of the patients who had been submitted to hematopoietic stem cell transplantation was 13.5% (n = 5) vs. 26.7% (n = 16) among patients not submitted to transplantation (p-value = 0.13). Of the 155 infections diagnosed, 45.5% were defined as clinically documented. The etiological agent most frequently isolated was Escherichia coli and the main topography reported was bloodstream infections. The most used antimicrobial agents were cefepime, vancomycin and fluconazole. Approximately 24% of patients evolved with impaired renal function during hospitalization. Conclusion Most reported infections in neutropenic patients were defined as clinically documented, which shows the importance of suspicion in patients without specific signs and symptoms for early diagnosis and the need for the classification of risk for timely interventions.

Impact of Model for End-Stage Liver Disease in the occurrence of infectious events and survival in a cohort of liver transplant recipients.

The Model for End-Stage Liver Disease (MELD), which predicts mortality on the waiting list before liver transplantation, has changed organ allocation criteria to prioritize severely ill patients. The aim of this study was to investigate the impact of the new criteria on the incidence of Healthcare Associated Infections (HAI) and patient survival after liver transplantation. This retrospective cohort included liver transplant recipients from 2005 to 2007. Infection notification followed the recommended criteria of the National Healthcare Safety Network (NHSN). Statistical analysis was performed using the Statistical Package for the Social Sciences. Of 142 patients, 67 (47.2%) underwent transplantation before June 2006. There were no differences between the 2 periods considering patient gender, diagnosis, age, length of hospitalization, and mean time to first infection occurrence. However, the length of intensive care unit (ICU) hospitalization (P = .006) and central venous catheter (CVC) use (P = .025) were higher in the first period of the study. Comparison of time until first systemic infection before and after changes in allocation criteria showed no significant difference (log-rank = 0.06; P = .81). There was a trend toward greater lethality during the second period of the study (P = .09). There was no difference in time to death between the 2 periods (log-rank = 0.9; P = .76). However, when comparing time to death of all patients with systemic infection versus those without this event, patients without infection showed a higher mortality rate (log-rank = 15.7; P < .001).

Clinical and microbiological characteristics of OXA-23- and OXA-143-producing Acinetobacter baumannii in ICU patients at a teaching hospital, Brazil

BACKGROUND Carbapenem-resistant Acinetobacter baumannii (CRAb) is an important cause of nosocomial infections especially in intensive care units. This study aimed to assess clinical aspects and the genetic background of CRAb among ICU patients at a Brazilian teaching hospital. METHODS 56 critically ill patients colonized or infected by CRAb, during ICU stay, were prospectively assessed. Based on imipenem MIC≥4μg/mL, 28 CRAB strains were screened for the presence of genes encoding metallo-β-lactamases and OXA-type β-lactamases. The blaOXA-type genes were characterized by PCR using primers targeting ISAba-1 or -3. Genetic diversity of blaOXA-positive strains was determined by ERIC-PCR analysis. RESULTS Patients mean age (±SD) was 61 (±15.1), and 58.9% were male. Eighty-percent of the patients presented risk factors for CRAb colonization, mainly invasive devices (87.5%) and previous antibiotic therapy (77.6%). Thirty-three patients died during hospital stay (59.0%). Resistance to carbapenems was associated with a high prevalence of blaOXA-23 (51.2%) and/or blaOXA-143 (18.6%) genes. ERIC-PCR genotyping identified 10 clusters among OXA-producing CRAb. Three CRAb strains exhibited additional resistance to polymyxin B (MIC≥4μg/mL), whereas 10 CRAb strains showed tigecycline MICs>2μg/mL. CONCLUSIONS In this study, clonally unrelated OXA-123- and OXA-143-producing A. baumannii strains in ICU patients were strongly correlated to colonization with infected patients being associated with a poor outcome.