Drug resistance in Mycobacterium tuberculosis strains isolated
from sputum samples from symptomatic outpatients –
Complexo de Manguinhos, Rio de Janeiro, Brazil*
Resistência a drogas em cepas de Mycobacterium tuberculosis isoladas
de amostras de escarro de pacientes ambulatoriais sintomáticos –
Complexo de Manguinhos, Rio de Janeiro, Brasil
Joycenea Matsuda Mendes1, Maria Cristina Lourenço2, Rosa Maria Carvalho Ferreira3,
Leila de Souza Fonseca4, Maria Helena Feres Saad5
This study aimed to assess drug resistance in Mycobacterium tuberculosis strains isolated from sputum samples. To that end, sputum samples
were collected from 263 patients suspected of having tuberculosis. All subjects lived in the Complexo de Manguinhos, which is located in
the city of Rio de Janeiro, Brazil. Cultures testing positive between October of 2000 and December of 2002 were tested to determine strain
susceptibility to isoniazid, rifampicin, streptomycin, ethionamide, and ethambutol. Of the 75 patients diagnosed with tuberculosis, resistance
to at least one of the drugs was found in 16 (21.4%). Of those 16 patients, 8 (50%) were new cases, and 8 (50%) had previously been
treated. Multidrug-resistant tuberculosis was identified in 8 (10.6%) of the 75 patients, being associated with previous treatment in 6 (8%).
The incidence of multidrug-resistant tuberculosis might have been underestimated, since M. tuberculosis was not isolated from all of the
samples testing positive for acid-fast bacilli. However, at least, our findings shed some light on the problem. Keywords:
Tuberculosis; Drug resistance; Drug resistance, multiple.
Para descrever a resistência a drogas em cepas de Mycobacterium tuberculosis isoladas de amostras de escarro de 263 pacientes suspeitos de
tuberculose moradores do Complexo de Manguinhos, Rio de Janeiro, Brasil, as culturas positivas entre outubro de 2000 e dezembro de 2002
foram submetidas a teste de sensibilidade para isoniazida, rifampicina, estreptomicina, etionamida e etambutol. Resistência a qualquer das
drogas foi encontrada em 21,4% (16/75) dos pacientes diagnosticados com tuberculose. Destes, 50% (8/16) eram casos novos e 50% (8/16)
eram casos com tratamento anterior. A tuberculose multirresistente foi encontrada em 10,6% (8/75) do total de pacientes, estando associada
a tratamento anterior em 8% (6/75) deles. Nossos resultados podem ter sido subestimados, pois M. tuberculosis não pôde ser isolado em
todas as amostras positivas para bacilos álcool-ácido resistentes. Contudo, eles pelo menos revelam parte do problema.Descritores:
Tuberculose; Resistência a drogas; Resistência a múltiplas drogas.
* Trabalho realizado no Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Fundação Osvaldo Cruz – FIOCRUZ – Rio de Janeiro (RJ) Brasil.
1. Mestre em Clínica Médica. Faculdade de Medicina da Universidade Federal do Rio de Janeiro – UFRJ – Rio de Janeiro (RJ) Brasil.
2. Pesquisadora Titular Chefe do Serviço de Bacteriologia. Instituto de Pesquisa Clínica Evandro Chagas – IPEC – Rio de Janeiro (RJ) Brasil.
3. Mestre em Ciências (Microbiologia) no Instituto de Microbiologia. Universidade Federal do Rio de Janeiro – UFRJ – Rio de Janeiro (RJ) Brasil.
4. Professora Titular. Universidade Federal do Rio de Janeiro – UFRJ – Rio de Janeiro (RJ) Brasil.
5. Pesquisadora Titular do Laboratório de Microbiologia Celular. Instituto Oswaldo Cruz – FIOCRUZ – Rio de Janeiro (RJ) Brasil.
Endereço para correspondência: Maria Helena Féres Saad. Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil, 4365, CEP 21045-900, Rio de Janeiro, RJ, Brasil.
Tel. 55 21 2598-4346. Fax. 55 21 2270-9997. E-mail: firstname.lastname@example.orgRecebido para publicação em 7/11/2006. Aprovado, após revisão, em 6/2/2007.
Mendes JM, Lourenço MC, Ferreira RMC, Fonseca LS, Saad MHF
Tuberculosis (TB) is the leading cause of mortality culture and susceptibility tests are not part of the
from infectious diseases worldwide, accounting for routine of the health care laboratory, they were approximately 2 million deaths each year, especially performed in the Mycobacteriology Laboratory of
in developing countries.(1,2) Despite the existence the FIOCRUZ-operated Evandro Chagas Research
of effective chemotherapy and the widespread use Institute. The M. tuberculosis strain isolates were
of the bacillus Calmette-Guérin (BCG) vaccine, the tested on Löwenstein-Jensen medium using the
disease has never been properly controlled in these standard proportion method for susceptibility to
isoniazid (INH), rifampicin (RIF), streptomycin (SM),
Brazil ranks fifteenth in the world in the number ethionamide (ETH) and ethambutol (EMB). An
of estimated cases, with an incidence rate of isolate was defined as resistant when the percentage
62/100,000 inhabitants.(3) Higher incidence rates of colonies exceeded 1% of the growth on a drug-
are seen in densely populated cities such as Rio free medium (control) at the critical concentrations
de Janeiro (114/100,000), which has the highest of 0.2, 40, 4.0, 20, and 2.0 µg/mL, respectively.(7,8)
TB-related mortality rate (6.53/100,000).(4,5)
Multidrug resistance (MDR) was defined as resis-
The TB situation can be even worse in areas with tance to at least INH and RIF. All TB cases diagnosed
socially vulnerable populations. One such area is the in the Complexo de Manguinhos were treated and
Complexo de Manguinhos, a slum located in the city monitored at the CSEGSF/ENSP/FIOCRUZ.
of Rio de Janeiro. Although the efforts made by the
Centro de Saúde Escola Germano Silval Faria (CSEGSF, 2002, sputum samples from 263 suspected cases of
Germano Sinval Faria School Health Center), working TB were analyzed by culture, and 80 of them were
in collaboration with the Escola Nacional de Saúde confirmed as cases of TB. However, 5 samples were
Pública (ENSP, National School of Public Health) contaminated, and therefore only 75 samples were
of the Fundação Oswaldo Cruz (FIOCRUZ, Oswaldo available for susceptibility testing. The mean age of
Cruz Foundation) have effectively lowered the TB the patients was 36 ± 14 years (range, 18-77 years),
incidence rate in the Complexo de Manguinhos,(6,7) and the majority of the patients were male
it remains high: 275, 260, and 235/100.000 in 1997, 1998, and 1999, respectively – data obtained (p = 0.04). Serology for HIV was available for 66 of from the CSEGSF/ENSP/FIOCRUZ Programa de the patients, 4 (6%) of whom were HIV-positive.
Controle da Tuberculose (PCT, Tuberculosis Control Data were unavailable for one patient, who was Program). However, drug resistance testing has reported to be in prison. never been performed. The objective of this study
As shown in Table 1, 59 (78.7%) of the 75 patients
was to describe drug-resistance in Mycobacterium were infected with strains susceptible to all drugs
tuberculosis strains isolated from adult individuals tested: 55 were new TB cases, and 4 were previously with respiratory symptoms and suspected of having treated TB cases. The overall rate of resistance was TB (cough for 3 weeks) who sought treatment at 21.3%: 12.7% of the new cases and 66.7% of the the CSEGSF/ENSP/FIOCRUZ between October of previously treated cases. Strains presenting mono-or 2000 and December of 2002.
multiple-resistance to SM were found to infect
The Complexo de Manguinhos comprises mainly new cases (4 of the 6 cases, 5.3% of the
12 communities with slum-like conditions. However, sample), and no strains showing mono-resistance to there are two exceptions, the communities designated RIF or ETH were detected. As expected, most of the CHP2 and Vila Turismo, which have large demogra- patients infected with MDR strains (6 of the 8 cases, phic populations and partial sanitation infrastructure 8% of the sample) had been previously treated, with treated water and a sewage system. Overall, the none were HIV-positive, and 2 (2.6% of the sample) Complexo de Manguinhos has 42,100 inhabitants were new cases, together accounting for 10.6% of distributed in approximately 8,000 houses (Rio de the sample. Of the 8 resistant new cases, 3 were Janeiro Institute for State Management Planning). found in the largest community in the Complexo de Physical examinations were carried out by the PCT Manguinhos, the CHP2; and MDR cases were found staff at the CSEGSF/ENSP/FIOCRUZ, at which time in two communities, Vila Turismo (7324 inhabitants) sputum specimens were obtained and tested for and Ex-Combatentes (934 inhabitants), although acid-fast bacilli (Ziehl-Neelsen staining).(7) Since resistant strains infecting previously treated patients
Drug resistance in Mycobacterium tuberculosis strains isolated from sputum samples
from symptomatic outpatients – Complexo de Manguinhos, Rio de Janeiro, Brazil
Table 1 -
Susceptibility testing of Mycobacterium tuberculosis strains isolated from tuberculosis patients (new and
previously treated cases) living in the Complexo de Manguinhos, Rio de Janeiro, Brazil, between October of 2000 and
December of 2002.
INH: isoniazid; RIF: rifampicin; EMB: ethambutol; and SM: streptomycin.
are more commonly found in communities with Mozambique.(10) The high incidence of drug-resistant more than 4000 inhabitants.
strains in Mozambique reflects a pattern found in
The overall rate of resistance in the Complexo de TB/HIV co-infected patients, who are more suscep-
Manguinhos was 21.4%, and, although the number tible to TB infection, and, according to the authors, of strains tested was small, the importance of this is associated with a high risk of exposure to resis-datum is that, in addition to being the first time tant strains due to failure on the part of the PCT. In that resistance was determined in the community the Complexo de Manguinhos, most of the patients studied, it was obtained in a high-burden, limited- were HIV-negative, and the resistance problem resource community (in Rio de Janeiro, Brazil) where, seemed to be related to treatment non-compliance, despite the existence of a public health care facility as indicated by the high incidence of MDR strains that preferentially serves this community, TB inci- infecting previously treated patients. In addition, dence rates remain a cause for concern.(9) The rate although the study population comprised only of mono-resistance to INH and SM obtained in this 36.4% of all TB patients diagnosed at the time, study was high. However, the SM mono-resistance, this situation might reflect the reality in the area. unlike the INH mono-resistance, which was more With regard to resistant strains infecting new cases, frequent among previously treated cases, was primary resistance should be strongly suspected in detected among new cases (Table 1). Similar results at least one patient, since his brother was under were obtained in TB/HIV co-infected patients in treatment for MDR-TB presenting the same resis-Mozambique.(10) This is a concern since treatment tance pattern, although molecular typing was not regimen I, which is recommended for untreated performed to confirm the genetic identity of the patients, does not contain SM, suggesting that older strains. Other factors might be involved in the resis-strains (related to endogenous reactivation) continue tance situation in the Complexo de Manguinhos. to circulate in the Complexo de Manguinhos. The One such factor is that, during the study period, number of HIV-positive patients in our sample was the PCT was closed or worked poorly because of low (6%), and the mean rate of TB/HIV co-infection the violence perpetrated by organized crime gangs in the study period was 16.3%.(9) This might have in the region.
created a bias in our results, since the isolates for
This study is the first to provide information
regarding drug resistance in the limited-resource
The rate of MDR-TB in the Complexo de area of the Complexo de Manguinhos, and the
Manguinhos was similar to that found in results show that the incidence of resistant strains
Mendes JM, Lourenço MC, Ferreira RMC, Fonseca LS, Saad MHF
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Applications for LA-(MC)-ICP-MS (text need some serious improvement) Stable isotopes: Li The two isotopes of lithium (7.5% of 6Li and 92.5% of 7 Li) have a relative mass differenceof approximately 16.6% (larger than B with 10% and 16O-18O with 12.5%). Hence Li isotopicfractionation seems to be a promising tool to monitor low surface chemical processes. Lithiumisotopic composition v
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