RESUMEN
SETTING: Montreal, Canada, has a mean annual tuberculosis (TB) incidence of 9 per 100,000 population, 1996-2007. OBJECTIVE: To characterise potential Mycobacterium tuberculosis transmission by patient subgroups defined by age, sex, birthplace, smear and human immunodeficiency virus status, and to estimate the proportion of cases that resulted from transmission between these patient subgroups. DESIGN: Retrospective study using DNA fingerprinting techniques, with clinical and demographic information from the public health department. Among cases with matching fingerprints, a pulmonary index case was identified. The transmission index was defined as the average number of subsequent TB cases generated directly or indirectly from an index case, and was compared among subgroups, including Haitian immigrants. RESULTS: Compared to non-Haitian foreign-born index cases, Canadian-born index cases were associated with 2.38 times as many (95%CI 1.24-4.58) subsequent cases, while Haitian-born index cases were associated with 3.58 times as many (95%CI 1.74-7.36). Smear-positive index cases were not independently associated with increased transmission. However, middle-aged Canadian-born index patients were associated with a disproportionate number of subsequent cases. CONCLUSION: In Montreal, index patients from several high-risk groups are associated with subsequent transmission. This approach can be applied to other low-incidence settings to identify where targeted interventions could potentially further reduce transmission.
Asunto(s)
Emigrantes e Inmigrantes/estadística & datos numéricos , Mycobacterium tuberculosis/aislamiento & purificación , Tuberculosis/epidemiología , Adolescente , Adulto , Factores de Edad , Anciano , Dermatoglifia del ADN/métodos , Femenino , Haití/etnología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Quebec/epidemiología , Estudios Retrospectivos , Factores de Riesgo , Tuberculosis/transmisión , Población Urbana , Adulto JovenRESUMEN
Nocardia is an uncommon pathogen, but immunosuppression, its main risk factor, is becoming more frequent. We aimed to evaluate changes in the annual incidence of nocardiosis and in the susceptibility profile of its aetiological agents. Demographic data were analysed for all isolates of Nocardia forwarded to the provincial public health laboratory of Quebec, Canada during the last two decades. Population incidence could be measured from 1997 onwards. Resistance patterns were analysed for those isolates selected for in vitro susceptibility testing. Throughout Quebec, 575 incident cases were identified between 1997 and 2008. The annual incidence of Nocardia infection/colonization increased from 0.33 (1997-1998) to 0.87 (2007-2008) per 100,000 inhabitants (p 0.001). In a small subset of patients for whom detailed clinical information was available, 59% of isolates corresponded to genuine infections. Nocardia farcinica predominated in specimens representing invasive infections (blood, brain, lung or pleural aspirates). Isolates were often non-susceptible to several antimicrobials, with the exception of amikacin and linezolid. Overall, 43% of 157 isolates were non-susceptible to trimethoprim-sulphamethoxazole. In conclusion, Nocardia infection/colonization remains rare. However, from 1997-1998, a progressive increase in incidence was noted in the province of Quebec. In regions such as ours, where a substantial proportion of invasive isolates are non-susceptible in vitro to trimethoprim-sulphamethoxazole, the latter may no longer be the empirical treatment of choice in immunosuppressed and severely ill patients with nocardiosis.
Asunto(s)
Nocardiosis/epidemiología , Nocardia , Anciano , Antibacterianos/uso terapéutico , Canadá/epidemiología , Femenino , Humanos , Huésped Inmunocomprometido , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Nocardia/efectos de los fármacos , Nocardia/aislamiento & purificación , Nocardiosis/tratamiento farmacológico , Nocardiosis/inmunología , Factores de Riesgo , Combinación Trimetoprim y Sulfametoxazol/uso terapéuticoRESUMEN
SETTING: In Canada, tuberculosis (TB) is increasingly an urban health problem. Montreal is Canada's second-largest city and the second most frequent destination for new immigrants and refugees. OBJECTIVES: To detect spatial aggregation of cases, areas of excess incidence and local 'hot spots' of transmission in Montreal. DESIGN: We used residential addresses to geocode active TB cases reported on the Island of Montreal in 1996-2000. After a hot spot analysis suggested two areas of overconcentration, we conducted a spatial scan, with census tracts (population 2500-8000) as the primary unit of analysis and stratification by birthplace. We linked these analyses with genotyping of all available Mycobacterium tuberculosis isolates, using IS6110-RFLP and spoligotyping. RESULTS: We identified four areas of excess incidence among the foreign-born (incidence rate ratios 1.3-4.1, relative to the entire Island) and one such area among the Canadian-born (incidence rate ratio 2.3). There was partial overlap with the two hot spots. Genotyping indicated ongoing transmission among the foreign-born within the largest high-incidence zone. While this zone overlapped the area of high incidence among Canadian-born, genotyping largely excluded transmission between the two groups. CONCLUSIONS: In a city with low overall incidence, spatial and molecular analyses highlighted ongoing local transmission.
Asunto(s)
ADN Bacteriano/análisis , Emigración e Inmigración , Tamizaje Masivo , Mycobacterium tuberculosis/genética , Polimorfismo de Longitud del Fragmento de Restricción , Características de la Residencia , Tuberculosis/transmisión , Salud Urbana , Adulto , Análisis por Conglomerados , Emigración e Inmigración/estadística & datos numéricos , Femenino , Genotipo , Humanos , Incidencia , Masculino , Tamizaje Masivo/estadística & datos numéricos , Persona de Mediana Edad , Mycobacterium tuberculosis/aislamiento & purificación , Quebec/epidemiología , Características de la Residencia/estadística & datos numéricos , Estudios Retrospectivos , Tuberculosis/epidemiología , Tuberculosis/genética , Tuberculosis/microbiología , Salud Urbana/estadística & datos numéricosRESUMEN
A group of pigmented, slowly growing mycobacteria identified by 16S rRNA gene sequencing as 'MCRO 33' (GenBank accession no. AF152559) have been isolated from several clinical specimens in various laboratories across Canada. Genotypically, the organism is most closely related to Mycobacterium simiae. However, it presents with a similar phenotypic profile to Mycobacterium scrofulaceum. Several reference strains obtained from ATCC and TMC culture collections, previously identified as M. scrofulaceum or M. simiae, have also been found to possess the MCRO 33 16S rRNA gene sequence. Biochemical testing, susceptibility testing, HPLC, hsp65 gene and 16S-23S spacer (ITS1) sequencing were performed on clinical and reference strains to characterize further this unique species. Of the clinical strains, one was isolated from a cervix biopsy whereas all other clinical isolates were obtained from respiratory samples. In one patient, symptoms, imaging and repeat clinical specimens positive on culture for this organism were suggestive of active clinical disease. The description of this species, for which the name Mycobacterium parascrofulaceum sp. nov. is proposed, follows the present trend of a large number of novel Mycobacterium species identified due in great part to sequence-based methods. The type strain is HSC68T (= ATCC BAA-614T = DSM 44648T).
Asunto(s)
Infecciones por Mycobacterium/microbiología , Micobacterias no Tuberculosas/clasificación , Micobacterias no Tuberculosas/aislamiento & purificación , Adulto , Anciano , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Técnicas de Tipificación Bacteriana , Líquido del Lavado Bronquioalveolar/microbiología , Canadá , Cuello del Útero/microbiología , Chaperonina 60 , Chaperoninas/genética , ADN Bacteriano/química , ADN Bacteriano/aislamiento & purificación , ADN Ribosómico/química , ADN Ribosómico/aislamiento & purificación , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/aislamiento & purificación , Femenino , Genes de ARNr , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Datos de Secuencia Molecular , Mycobacterium scrofulaceum/clasificación , Ácidos Micólicos/análisis , Micobacterias no Tuberculosas/genética , Micobacterias no Tuberculosas/fisiología , Filogenia , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Esputo/microbiologíaRESUMEN
A pigmented, slowly growing Mycobacterium avium complex AccuProbe-positive organism was isolated from the sputum and pleural fluid of a 72-year-old female with bronchiectasis. The unusual morphology of the organism prompted further identification by 16S rRNA gene sequencing, revealing a perfect identity with previously uncharacterized strain Mycobacterium sp. MCRO 8 (GenBank accession no. X93034), with the closest established species by 16S rDNA analysis being Mycobacterium interjectum. HPLC of the organism corresponded to previously obtained patterns identified as M. interjectum-like and, upon sequence evaluation of a selection of strains with a similar profile, more were subsequently identified as MCRO 8. A total of 16 strains isolated from human respiratory samples were evaluated in the characterization of this novel species, for which the name Mycobacterium saskatchewanense sp. nov. is proposed. The type strain is strain 00-250(T) (=ATCC BAA-544(T)=DSM 44616(T)=CIP 108114(T)).
Asunto(s)
Complejo Mycobacterium avium/clasificación , Complejo Mycobacterium avium/aislamiento & purificación , Micobacterias no Tuberculosas/clasificación , Micobacterias no Tuberculosas/aislamiento & purificación , Proteínas Bacterianas/genética , Técnicas de Tipificación Bacteriana , Secuencia de Bases , Chaperonina 60 , Chaperoninas/genética , ADN Bacteriano/genética , ADN Intergénico/genética , Farmacorresistencia Bacteriana , Genes Bacterianos , Humanos , Datos de Secuencia Molecular , Ácidos Micólicos/análisis , Micobacterias no Tuberculosas/genética , Micobacterias no Tuberculosas/metabolismo , Fenotipo , Filogenia , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Homología de Secuencia de Ácido NucleicoRESUMEN
Mycobacterium branderi, a potential human pathogen first characterized in 1995, has been isolated from respiratory tract specimens. We report here a case in which M. branderi was the only organism isolated upon culture from a hand infection. This isolate, along with a second isolate from a bronchial specimen, was subjected to conventional identification tests for mycobacterial species. Further analysis by high-performance liquid chromatography (HPLC) of mycolic acids and 16S rRNA gene sequencing was performed, and the antibiotic susceptibility profile was determined for both strains. Biochemical tests and the HPLC pattern were consistent with that of M. branderi and M. celatum, which are very similar. The 16S rRNA gene sequence of both strains corresponded to that of M. branderi and enabled us to confidently differentiate this organism from other closely related species such as M. celatum. This contributes to a further understanding of the status of this species as a potential human pathogen as well as illustrating the need for molecular diagnostics as a complementary method for the identification of rare mycobacterial species.
Asunto(s)
Ciprofloxacina/uso terapéutico , Claritromicina/uso terapéutico , Quimioterapia Combinada/uso terapéutico , Enfermedades Pulmonares/microbiología , Infecciones por Mycobacterium/diagnóstico , Mycobacterium/clasificación , Enfermedades Cutáneas Bacterianas/diagnóstico , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico , Cromatografía Líquida de Alta Presión , ADN Ribosómico/genética , Femenino , Mano , Humanos , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/tratamiento farmacológico , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Mycobacterium/crecimiento & desarrollo , Mycobacterium/aislamiento & purificación , Infecciones por Mycobacterium/tratamiento farmacológico , Ácidos Micólicos/análisis , ARN Ribosómico 16S/genética , Enfermedades Cutáneas Bacterianas/tratamiento farmacológicoRESUMEN
Pyrazinamide (PZA) is an important first-line tuberculosis drug that is part of the currently used short-course tuberculosis chemotherapy. PZA is a prodrug that has to be converted to the active form pyrazinoic acid by pyrazinamidase (PZase) activity, encoded by the pncA gene of Mycobacterium tuberculosis, and loss of PZase activity is associated with PZA resistance. To further define the genetic basis of PZA resistance and determine the frequency of PZA-resistant strains having pncA mutations, we sequenced the pncA gene from a panel of 59 PZA-resistant clinical isolates from Canada, the United States, and Korea. Two strains that did not contain pncA mutations and had positive PZase turned out to be falsely resistant. Three PZase-negative strains (MIC, >900 microgram of PZA per ml) and one PZase-positive strain (strain 9739) (MIC, >300 microgram of PZA per ml) did not have pncA mutations. The remaining 53 of the 57 PZA-resistant isolates had pncA mutations, confirming that pncA mutation is the major mechanism of PZA resistance. Various new and diverse mutations were found in the pncA gene. Interestingly, 20 PZA-monoresistant strains and 1 multidrug-resistant isolate from Quebec, Canada, all had the same pncA mutation profile, consisting of an 8-nucleotide deletion and an amino acid substitution of Arg140-->Ser. Strain typing indicated that these strains are highly related and share almost identical IS6110 patterns. These data strongly suggest the spread of a PZA-monoresistant strain, which has not previously been described.
Asunto(s)
Amidohidrolasas/genética , Antituberculosos/farmacología , Mutación , Mycobacterium tuberculosis/efectos de los fármacos , Pirazinamida/farmacología , Tuberculosis/microbiología , Amidohidrolasas/metabolismo , Dermatoglifia del ADN , Elementos Transponibles de ADN , ADN Bacteriano/análisis , Farmacorresistencia Microbiana/genética , Humanos , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/genética , Reacción en Cadena de la Polimerasa , Quebec , Análisis de Secuencia de ADN , Tuberculosis/transmisión , Tuberculosis Resistente a Múltiples Medicamentos/microbiologíaRESUMEN
We have previously found that approximately 3.5% of 428 clinical isolates of Mycobacterium tuberculosis yield uninterpretable results in the BACTEC pyrazinamide (PZA) susceptibility test system, because of inadequate growth. We tested the hypothesis that polyoxyethylene stearate (POES), the ingredient of the reconstituting fluid for the test, was the cause of this growth inhibition. A total of 15 isolates known for their previously uninterpretable results and 100 randomly chosen clinical isolates were tested in parallel both with and without POES. Repeat testing of the isolates with previously uninterpretable results yielded results in the presence of POES in only seven (47%). In the absence of POES, all gave interpretable results but one such result showed false resistance. For the other 100 clinical isolates, interpretable results were obtained with and without POES, but growth was enhanced in the absence of POES, especially in the PZA-susceptible strains. This was evidenced by a decreased time to attain a growth index of 200 in the control vial (4.9 days without POES versus 5.8 days with POES; P < 0.001) and a higher mean growth index ratio on the day of interpretation of the test (7.4% without POES versus 2.2% with POES; P < 0.001). However, the enhanced growth without POES led to 20 susceptible strains being misinterpreted as either resistant or borderline. We suggest that isolates of M. tuberculosis which yield uninterpretable results in the BACTEC PZA test system should be retested both with and without POES. If interpretable results indicating PZA resistance are obtained only in the absence of POES, the result should be confirmed by a pyrazinamidase assay or by the conventional proportion method. Routine omission of POES from the BACTEC test for all clinical strains is discouraged because of the unacceptably high false-resistance rates.
Asunto(s)
Pruebas de Sensibilidad Microbiana/métodos , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/crecimiento & desarrollo , Polietilenglicoles/farmacología , Antituberculosos/farmacología , División Celular/efectos de los fármacos , Farmacorresistencia Microbiana , Humanos , Técnicas In Vitro , Indicadores y Reactivos , Pruebas de Sensibilidad Microbiana/estadística & datos numéricos , Pirazinamida/farmacología , Tuberculosis Pulmonar/tratamiento farmacológico , Tuberculosis Pulmonar/microbiologíaRESUMEN
The susceptibility of 428 clinical isolates of Mycobacterium tuberculosis to pyrazinamide was assessed by the Bactec method and the Wayne pyrazinamidase assay. The correlation between the two tests was 98.2 and 100% for susceptible and resistant strains, respectively. False resistance was seen in four (0.8%) strains with the Bactec test, and false-susceptible results occurred in two (0.5%) pyrazinamidase assays. The Bactec test is rapid and reliable, and the Bactec results correlate well with the pyrazinamidase test results, although some strains did not grow well in the test medium.
Asunto(s)
Antituberculosos/farmacología , Mycobacterium tuberculosis/efectos de los fármacos , Pirazinamida/farmacología , Pruebas de Sensibilidad Microbiana , Sensibilidad y EspecificidadRESUMEN
Mycolic acid analysis by high-performance liquid chromatography (HPLC) was introduced in our laboratory as the routine technique for identifying all clinical isolates of mycobacteria referred to us. HPLC identified 96.1% of the 1,103 strains analyzed, whereas the biochemical procedures and/or the commercial DNA probes identified 98.3% of strains, for an overall agreement of 94.4%. Compared with the probes, there was 100% specificity and 98.9% sensitivity for Mycobacterium tuberculosis identification. HPLC allowed early detection and identification of the rare mycobacterial species M. haemophilum, M. malmoense, M. shimoidei, and M. fallax as well as uncharacteristic strains of M. simiae. After 18 months of routine use, HPLC proved to be reliable, easy to perform, rapid, and less costly than other identification methods.
Asunto(s)
Técnicas Bacteriológicas , Cromatografía Líquida de Alta Presión/métodos , Mycobacterium/química , Ácidos Micólicos/análisis , Técnicas de Tipificación Bacteriana/estadística & datos numéricos , Técnicas Bacteriológicas/estadística & datos numéricos , Cromatografía Líquida de Alta Presión/estadística & datos numéricos , Sondas de ADN , Estudios de Evaluación como Asunto , Humanos , Técnicas de Sonda Molecular/estadística & datos numéricos , Mycobacterium/genética , Mycobacterium/aislamiento & purificación , Sensibilidad y Especificidad , Especificidad de la EspecieRESUMEN
Strains of Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, Mycobacterium xenopi, and Mycobacterium gordonae were identified by high-performance liquid chromatography (HPLC) analysis of mycolic acids as bromophenacyl esters. HPLC criteria were used to develop a flow chart identification scheme, which was evaluated in our laboratory with a set of 234 strains representing five species and a hitherto undescribed species. Correct identifications of M. gordonae and M. xenopi were easily made. Flow chart differentiation of M. avium, M. intracellulare, and M. scrofulaceum was done with 97.9, 97.5, and 89.2% accuracies, respectively. Independent evaluation of the flow chart at a separate laboratory demonstrated an overall identification accuracy of 97% for M. avium complex. Strains that have been described biochemically as being intermediate between M. avium-M. intracellulare and M. scrofulaceum were identified as one or the other of these known species. Strains which were negative with the species-specific radioactive probe for M. avium complex but which were positive with the nonradioactive SNAP X probe were usually identified as M. intracellulare and M. scrofulaceum but rarely as M. avium.
Asunto(s)
Cromatografía Líquida de Alta Presión , Complejo Mycobacterium avium/clasificación , Mycobacterium/clasificación , Árboles de Decisión , Mycobacterium/química , Complejo Mycobacterium avium/químicaAsunto(s)
Infecciones por Mycobacterium/epidemiología , Mycobacterium/aislamiento & purificación , Técnicas Bacteriológicas , Canadá/epidemiología , Estudios Transversales , Humanos , Incidencia , Mycobacterium/patogenicidad , Infecciones por Mycobacterium/microbiología , Infecciones Oportunistas/epidemiología , Infecciones Oportunistas/microbiologíaRESUMEN
In 1987, Mycobacterium haemophilum was isolated from cutaneous lesions, a lymph node, and the right eye of a male patient with acquired immunodeficiency syndrome and also from a cervical lymph node in a 3-year-old girl. These two cases are the first M. haemophilum infections to be reported in Canada.