PubMed · 11629549
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E Quevedo. [Not Available].. https://pubmed.ncbi.nlm.nih.gov/11629549/
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Hyphae and vesicles of arbuscular mycorrhizal fungi (AMF) were found within the decomposing leaves of Myrica parvifolia, M. pubescens and Paepalanthus sp. at three montane sites in Colombia. Hyphae, vesicles, and arbuscule-like structures were also found within scale-like leaves of the rhizomes of Paepalanthus sp. The litter found in the vicinity of the roots was divided into three decomposition layers. The highest AMF colonization occurred in the most decomposed leaves, which were in close association with roots. In contrast, there were no differences in AMF colonization of roots present in the different decomposition layers. Colonization of decomposing leaves by AMF did not differ between the two closely related species M. parvifolia and M. pubescens, nor between two sites (Guatavita and Zipacón, Colombia) differing in soil fertility. Occurrence of vesicles in decomposing leaves was correlated with abundant AMF extraradical hyphae among the leaves. We propose that AMF enter decomposing leaves mechanically through vascular tissue. As a consequence, AMF are well positioned to obtain and efficiently recycle mineral nutrients released by decomposer microorganisms before their loss by leaching or immobilization in soil.
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The present study was set up to determine vancomycin tolerance in Colombian, multiresistant, invasive, paediatric isolates of Streptococcus pneumoniae. A total of seven clinical isolates of penicillin-resistant S. pneumoniae, serotype 14, corresponding to the Spain(9v)-3 clone, were studied. Isolates were grown in Todd Hewitt broth at 37 degrees C. Growth (A(595)) and cell viability (cfu/ml) were monitored hourly for 4 h after addition of vancomycin at 10x MIC. S. pneumoniae R6 was used as a control for growth. For R6, the mean decrease in A(595) and cell viability (log(10) cfu/ml) after 4 h of vancomycin treatment (in 10 independent experiments) was 95.1% and 4.2 log(10), respectively. Six out of seven isolates exhibited similar behaviour. In contrast, for S. pneumoniae E239, the mean decrease in A(595) and cell viability was 48.5% and 2.2 log(10) after 4 h of vancomycin exposure, which suggested the presence of tolerance to vancomycin. The emergence of vancomycin-tolerant strains is of great concern in Colombia, owing to the alarming increase in resistance to penicillin.