Environmental factors affecting the occurrence of mycobacteria in brook sediments

Iivanainen, Eila; Martikainen, Pertti J.; Väauml, P.; nänen,; Katila, Marja–Leena

doi:10.1046/j.1365-2672.1999.00711.x

Cited by 58 publications

(57 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, the fast-growing, saprophytic mycobacteria grow over a wider pH range than the pathogenic, slow-growing mycobacteria (16,69). This may reflect that the environments in which saprophytic mycobacteria reside, such as soil and water, are often acidic (43). Remarkably, mycobacterial species were found greatly enriched in extremely acidic volcanic rock at pH 1 (100).…”

Section: Figmentioning

confidence: 97%

Acid Resistance inMycobacterium tuberculosis

2009

View full text Add to dashboard Cite

Section: Figmentioning

confidence: 97%

Acid Resistance inMycobacterium tuberculosis

2009

View full text Add to dashboard Cite

“…This pH helps mycobacteria to survive inside the phagocytic vacuole of host macrophages, where the intraphagosomal pH is mildly acidic, i.e., pH 6.1 to 6.5. Saprophytic bacteria grow in soil and aquatic habitats and can withstand very acidic conditions (pH 3.5 to 4.3) (17,18) owing to their cell walls, which are rigid. Nevertheless, the strong acidic pH of gastric aspirates (usually between 1.5 and 3.5) might contain the overgrowth of most nonpathogenic bacteria, fungi, and parasites, but mycobacteria can survive in this hostile environment.…”

Section: Discussionmentioning

confidence: 99%

Does Neutralization of Gastric Aspirates from Children with Suspected Intrathoracic Tuberculosis Affect Mycobacterial Yields on MGIT Culture?

Parashar¹,

Kabra

Lodha

et al. 2013

J Clin Microbiol

View full text Add to dashboard Cite

The microbiological confirmation of pulmonary tuberculosis in children relies on cultures of gastric aspirate (GA) specimens. Conventionally, GAs are neutralized to improve culture yields of mycobacteria. However, there are limited data to support this practice. To study the utility of neutralization of GAs with sodium bicarbonate in children with intrathoracic tuberculosis, a total of 116 children of either sex, aged 6 months to 14 years (median age, 120 months; interquartile range [IQR], 7 to 192 months), underwent gastric aspiration on 2 consecutive days. Gastric aspirates were divided into two aliquots, and only one aliquot was neutralized with 1% sodium bicarbonate. Both aliquots were processed for smear and culture examinations. Out of the 232 gastric aspirates, 12 (5.17%) were acid-fast bacilli (AFB) smear positive. There were no differences in smear positivity rates from samples with or without neutralization. The yield of Mycobacterium tuberculosis on a Bactec MGIT 960 culture system was significantly lower in the neutralized samples (16.3% [38/232]) than in the nonneutralized samples (21.5% [50/232]) (P ‫؍‬ 0.023). There was no significant difference between the neutralized and the nonneutralized samples in time to detection using the MGIT 960 system (average, 24.6 days; IQR, 12 to 37 days) (P ‫؍‬ 0.9). The contamination rates were significantly higher in the neutralized samples than in the nonneutralized samples (17.2% [40/232] versus 3.9% [9/232]) (P ‫؍‬ 0.001). The agreement for positive mycobacterial culture between the two approaches was 66.5% (P ‫؍‬ 0.001). Hence, we recommend that gastric aspirate samples not be neutralized with sodium bicarbonate prior to culture for M. tuberculosis. Diagnosis of tuberculosis (TB) in children is based on history, clinical examination, the results of tuberculin skin testing, and imaging. Microbiological confirmation is difficult in children (1) because of the paucibacillary nature of mycobacteria (2, 3). The bacteriological confirmation has relied on the culture of specimens from sequential gastric lavages (4). Gastric aspirates (GAs) are reported to yield smear positivity in no more than 20% of children and positive cultures in less than 50% of children with suspected tuberculosis. Neutralization of gastric aspirates with sodium bicarbonate is conventionally recommended to improve yield on culture (5, 6). To our knowledge, there have been no studies that evaluated the efficacy of neutralization of gastric aspirates with sodium bicarbonate or sodium carbonate. We report here our experience using the liquid Bactec MGIT 960 culture system to perform mycobacterial cultures on gastric aspirates, with and without neutralization with sodium bicarbonate, from children with newly diagnosed intrathoracic tuberculosis. MATERIALS AND METHODSStudy sites and population. This prospective clinical study was conducted in two settings, the All India Institute of Medical Sciences and the Kalawati Saran Children Hospital in New Delhi, India, between January and June 2010. A total ...

show abstract

“…From 1989 through 1996, we isolated unidentifiable mycobacteria from specimens taken from four human patients and one goat. Isolates shown to be similar by means of gas liquid chromatography (GLC) analyses of cellular fatty acid and alcohol composition and biochemical testing (12) were also detected among environmental isolates grown from water taken from Finnish streams in 1990 (4). These isolates have recently been verified as M. bohemicum by partial sequencing of the 16S rRNA gene.…”

mentioning

confidence: 89%

Characterization of Mycobacterium bohemicum Isolated from Human, Veterinary, and Environmental Sources

et al. 2001

View full text Add to dashboard Cite

Chemotaxonomic and genetic properties were determined for 14 mycobacterial isolates identified as members of a newly described species Mycobacterium bohemicum. The isolates recovered from clinical, veterinary, and environmental sources were compared for lipid composition, biochemical test results, and sequencing of the 16S ribosomal DNA (rDNA) and the 16S-23S rDNA internal transcribed spacer (ITS) regions. The isolates had a lipid composition that was different from those of other known species. Though the isolates formed a distinct entity, some variations were detected in the features analyzed. Combined results of the phenotypic and genotypic analyses were used to group the isolates into three clusters. The major cluster (cluster A), very homogenous in all respects, comprised the M. bohemicum type strain, nine clinical and veterinary isolates, and two of the five environmental isolates. Three other environmental isolates displayed an insertion of 14 nucleotides in the ITS region; they also differed from cluster A in fatty alcohol composition and produced a positive result in the Tween 80 hydrolysis test. Among these three, two isolates were identical (cluster B), but one isolate (cluster C) had a unique high-performance liquid chromatography profile, and its gas liquid chromatography profile lacked 2-octadecanol, which was present in all other isolates analyzed. Thus, sequence variation in the 16S-23S ITS region was associated with interesting variations in lipid composition. Two of the isolates analyzed were regarded as potential inducers of human or veterinary infections. Each of the environmental isolates, all of which were unrelated to the cases presented, was cultured from the water of a different stream. Hence, natural waters are potential reservoirs of M. bohemicum.In the past few years, species descriptions of several unclassified mycobacteria have been published, and more new species will certainly be identified in the future. In 1998, a novel species, Mycobacterium bohemicum, isolated from a patient with Down's syndrome and tuberculosis, was described by Reischl and coworkers (11). Only one additional report on this species has been presented so far (17). Despite its recent discovery, M. bohemicum seems to be more common than many of the other newly classified species. From 1989 through 1996, we isolated unidentifiable mycobacteria from specimens taken from four human patients and one goat. Isolates shown to be similar by means of gas liquid chromatography (GLC) analyses of cellular fatty acid and alcohol composition and biochemical testing (12) were also detected among environmental isolates grown from water taken from Finnish streams in 1990 (4). These isolates have recently been verified as M. bohemicum by partial sequencing of the 16S rRNA gene. In 1999, an additional three clinical isolates were identified as M. bohemicum.We describe here the characteristics of Finnish M. bohemicum isolates originating from clinical, veterinary, and environmental sources, together with some descriptions of the so...

show abstract

Environmental factors affecting the occurrence of mycobacteria in brook sediments

Cited by 58 publications

References 28 publications

Acid Resistance inMycobacterium tuberculosis

Acid Resistance inMycobacterium tuberculosis

Does Neutralization of Gastric Aspirates from Children with Suspected Intrathoracic Tuberculosis Affect Mycobacterial Yields on MGIT Culture?

Characterization of Mycobacterium bohemicum Isolated from Human, Veterinary, and Environmental Sources

Contact Info

Product

Resources

About