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1.
Paediatr Child Health ; 26(4): 205-207, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34131457

RESUMO

Mycobacterium avium complex (MAC) is usually considered an opportunistic organism, which infects immunocompromised children or those with structural airway abnormalities. We present two cases of MAC infection affecting immune competent children, likely from hot tubs with primary involvement of pulmonary and urinary systems. These cases highlight the importance of asking about hot tub use in immune competent children with suspected or confirmed MAC infections.

3.
J Chemother ; 32(4): 179-187, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32393118

RESUMO

Methicillin-resistant Staphylococcus aureus (MRSA) has unfortunately become a common pathogen in many healthcare facilities. In many institutions, vancomycin remains the preferred agent for treating serious MRSA infections including bacteraemia with or without endocarditis. The mutant prevention concentration (MPC) testing ≥109 colony forming units of bacteria, describes the antimicrobial drug concentration blocking the growth of the least susceptible cell from high density bacterial populations. With blood culture isolates of MRSA, we discovered strains with MPC values ≥32 µg/ml and viable cells could be readily recovered from agar plates containing 32 µg/ml of vancomycin. To investigate MRSA strains surviving in high concentrations of vancomycin on drug containing agar plates, we utilized electron microscopy to measure cell wall thickness as this has been previously reported as a potential mechanism of resistance1 along with septum thickening. Our data shows MRSA replication from high density bacterial populations in the presence of ≥32 µg/ml of vancomycin. Such observations may explain vancomycin failure in some patients and/or persistent bacteraemia and could potentially question the use of this drug in some critically ill patients in favour of an alternative agent.


Assuntos
Antibacterianos/farmacologia , Staphylococcus aureus Resistente à Meticilina/citologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Vancomicina/farmacologia , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Microscopia Eletrônica
5.
Sci Rep ; 8(1): 2356, 2018 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-29402937

RESUMO

Staphylococcus species are emerging opportunistic pathogens that cause outbreaks of hospital and community-acquired infections. Some of these bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are difficult to treat due to their resistance to multiple antibiotics. We carried out a comparative study on the lipidome adaptations in response to starvation in the two most common coagulase-negative Staphylococcus species: a S. epidermidis strain sensitive to ampicillin and erythromycin and a S. haemolyticus strain resistant to both. The predominant fatty acid composition in glycerolipids was (17:0-15:0) in both bacteria. During the exponential phase, the two bacterial lipidomes were similar. Both were dominated by diacylglycerol (DAG), phosphatidylglycerol (PG), lysyl-phosphatidylglycerol (Lysyl-PG) and Diglucosyl-diacylglycerol (DGDG). Alanyl-PG was detected in small amounts in both bacterial lipids. N-succinyl-lysyl-PG was detected only in S. haemolyticus, while lysyl-DAG only in S. epidermidis. As the two bacteria entered stationary phase, both lipidomes became essentially nitrogen-free. Both bacteria accumulated large amounts of free fatty acids. Strikingly, the lipidome of S. epidermidis became dominated by cardiolipin (CL), while that of S. haemolyticus was simplified to DGDG and PG. The S. epidermidis strain also produced acyl-phosphatidylglycerol (APG) in the stationary phase.


Assuntos
Adaptação Fisiológica , Metabolismo dos Lipídeos , Staphylococcus epidermidis/química , Staphylococcus epidermidis/metabolismo , Staphylococcus haemolyticus/química , Staphylococcus haemolyticus/metabolismo , Cardiolipinas/análise , Ácidos Graxos/análise , Glicolipídeos/análise , Fosfolipídeos/análise , Staphylococcus epidermidis/crescimento & desenvolvimento , Staphylococcus haemolyticus/crescimento & desenvolvimento
6.
Sci Rep ; 8(1): 7470, 2018 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-29748546

RESUMO

Bacteria inhabit a vast range of biological niches and have evolved diverse mechanisms to cope with environmental stressors. The genus Acinetobacter comprises a complex group of Gram-negative bacteria. Some of these bacteria such as A. baumannii are nosocomial pathogens. They are often resistant to multiple antibiotics and are associated with epidemic outbreaks. A. radioresistens is generally considered to be a commensal bacterium on human skin or an opportunistic pathogen. Interestingly, this species has exceptional resistance to a range of environmental challenges which contributes to its persistence in clinical environment and on human skin. We studied changes in its lipid composition induced by the onset of stationary phase. This strain produced triglycerides (TG) as well as four common phospholipids: phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL) and lysocardiolipin (LCL). It also produced small amounts of acyl-phosphatidylglycerol (APG). As the bacterial growth entered the stationary phase, the lipidome switched from one dominated by PE and PG to another dominated by CL and LCL. Surprisingly, bacteria in the stationary phase produced N-acyl-phosphatidylethanolamine (NAPE) and another rare lipid we tentatively name as 1-phosphatidyl-2-acyl-glycero-3-phosphoethanolamine (PAGPE) based on tandem mass spectrometry. It is possible these tri-acylated lipids play an important role in coping with nutrient depletion.


Assuntos
Acinetobacter/crescimento & desenvolvimento , Glicerofosfolipídeos/metabolismo , Acinetobacter/química , Acinetobacter/metabolismo , Infecções por Acinetobacter/microbiologia , Acilação , Glicerofosfolipídeos/análise , Humanos , Espectrometria de Massas em Tandem
9.
PLoS One ; 6(2): e16864, 2011 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-21359221

RESUMO

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of nearly half of the world's population. Genotypic characterization of H. pylori strains involves the analysis of virulence-associated genes, such as vacA, which has multiple alleles. Previous phylogenetic analyses have revealed a connection between modern H. pylori strains and the movement of ancient human populations. In this study, H. pylori DNA was amplified from the stomach tissue of the Kwäday Dän Ts'ìnchi individual. This ancient individual was recovered from the Samuel Glacier in Tatshenshini-Alsek Park, British Columbia, Canada on the traditional territory of the Champagne and Aishihik First Nations and radiocarbon dated to a timeframe of approximately AD 1670 to 1850. This is the first ancient H. pylori strain to be characterized with vacA sequence data. The Tatshenshini H. pylori strain has a potential hybrid vacA m2a/m1d middle (m) region allele and a vacA s2 signal (s) region allele. A vacA s2 allele is more commonly identified with Western strains, and this suggests that European strains were present in northwestern Canada during the ancient individual's time. Phylogenetic analysis indicated that the vacA m1d region of the ancient strain clusters with previously published novel Native American strains that are closely related to Asian strains. This indicates a past connection between the Kwäday Dän Ts'ìnchi individual and the ancestors who arrived in the New World thousands of years ago.


Assuntos
DNA Bacteriano/análise , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/patologia , Helicobacter pylori/genética , Camada de Gelo/microbiologia , Autopsia , Sequência de Bases , Canadá , Infecções por Helicobacter/história , Helicobacter pylori/classificação , Helicobacter pylori/isolamento & purificação , História Antiga , Humanos , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , Estômago/microbiologia , Estômago/patologia
11.
Can J Microbiol ; 51(10): 863-74, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16333346

RESUMO

Flagellin genes from the anaerobic Gram-negative beer-spoilage bacteria Pectinatus cerevisiiphilus and Pectinatus frisingensis were sequenced and the flagellin proteins initially characterized. Protein microsequencing led to the design of two degenerate PCR primers that allowed the P. cerevisiiphilus flagellin gene to be partially sequenced. A combination of PCR and Bubble PCR was then used to sequence the flagellin genes of three isolates from each species. Cloning and gene expression, followed by immunoblotting, confirmed the gene identities as flagellin. Analysis of the gene sequences revealed proteins similar to other bacterial flagellins, including lengths of 446 or 448 amino acids, putative sigma 28 promoters, and a termination loop. Antibody binding studies with isolated flagella correlated with gene sequence comparisons, with both indicating that the P. cerevisiiphilus isolates studied are very similar but that the P. frisingensis isolates show greater variation. Purified flagellins were found to be glycosylated, probably through an O linkage. Phylogenetic analysis revealed greater diversity within the flagellin sequences than within the 16S rRNA genes. Despite the Gram-negative morphology of Pectinatus, this genus proved most closely related to Gram-positive Firmicutes.


Assuntos
Cerveja/microbiologia , Flagelina/química , Flagelina/genética , Pectinatus/classificação , Pectinatus/genética , Sequência de Aminoácidos , Clonagem Molecular , Flagelina/metabolismo , Glicosilação , Dados de Sequência Molecular , Pectinatus/metabolismo , Filogenia , Análise de Sequência de DNA
12.
Can J Microbiol ; 50(7): 482-8, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15381972

RESUMO

Species taxonomy within the Lactobacillus casei group of bacteria has been unsettled. With the goal of helping clarify the taxonomy of these bacteria, we investigated the first 3 variable regions of the 16S rRNA gene, the 16S-23S rRNA interspacer region, and one third of the chaperonin 60 gene for Lactobacillus isolates originally designated as L. casei, L. paracasei, L. rhamnosus, and L. zeae. For each genetic region, a phylogenetic tree was created and signature sequence analysis was done. As well, phenotypic analysis of the various strains was performed by immunoblotting. Both sequence signature analysis and immunoblotting gave immediate identification of L. casei, L. rhamnosus, and L. zeae isolates. These results corroborate and extend previous findings concerning these lactobacilli; therefore, we strongly endorse recent proposals for revised nomenclature. Specifically, isolate ATCC 393 is appropriately rejected as the L. casei type strain because of grouping with isolates identified as L. zeae. As well, because all other L. casei isolates, including the proposed neotype isolate ATCC 334, grouped together with isolates designated L. paracasei, we support the use of the single species L. casei and rejection of the name L. paracasei.


Assuntos
Proteínas de Bactérias/análise , Chaperonina 60/genética , DNA Espaçador Ribossômico/química , DNA Ribossômico/química , Lactobacillus/classificação , Proteínas de Bactérias/imunologia , Proteínas de Bactérias/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , DNA Ribossômico/isolamento & purificação , DNA Espaçador Ribossômico/isolamento & purificação , Genes de RNAr , Immunoblotting , Lactobacillus/genética , Lacticaseibacillus casei/classificação , Lacticaseibacillus casei/genética , Dados de Sequência Molecular , Filogenia , Proteoma/análise , Proteoma/imunologia , Proteoma/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Homologia de Sequência
13.
Microbiology (Reading) ; 141 ( Pt 8): 1985-1992, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7551061

RESUMO

The reduction of exogenous ferric iron by Listeria monocytogenes, a Gram-positive food-borne pathogen, was investigated. Using an assay incorporating the ferrous iron chelator ferrozine, we showed that intact cells of L. monocytogenes, when exposed to ferric iron, were able to rapidly reduce and solubilize the iron to the ferrous form. Reduction occurred only after direct contact between the bacteria and the iron source. A number of different ferric iron chelates, including transferrin and lactoferrin-bound iron, haemoglobin, ferritin, and iron complexed to siderophores, could be reduced. The ferric reductase activity was expressed by both reference strains and clinical isolates of L. monocytogenes and by all other species of Listeria, although significant quantitative differences were observed. In L. monocytogenes, the expression of ferric reductase was not affected by the growth phase of the bacteria nor by the presence or absence of iron in the growth medium. However, expression was greatly reduced in bacteria grown anaerobically and when cultured in media of reduced pH. In addition, bacteria grown at a cold temperature displayed greater ferric reductase activity than cells grown at higher temperatures. A surface-associated ferric reductase system may be one component of a general iron scavenging mechanism which can be used by Listeria growing in a variety of environments.


Assuntos
Proteínas de Bactérias/metabolismo , FMN Redutase , Compostos Férricos/metabolismo , Listeria monocytogenes/metabolismo , Proteínas de Membrana/metabolismo , NADH NADPH Oxirredutases/metabolismo , Aerobiose , Coenzimas/química , Ferrozina/química , Concentração de Íons de Hidrogênio , Quelantes de Ferro/metabolismo , Listeria/genética , Listeria/metabolismo , Listeria monocytogenes/crescimento & desenvolvimento , Magnésio/química , Metaloproteínas/metabolismo , NADH NADPH Oxirredutases/biossíntese , Oxirredução , Temperatura , Fatores de Tempo
14.
Int J Syst Evol Microbiol ; 52(Pt 6): 2003-2010, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12508860

RESUMO

Pediococci are found in foods and on plants and as beer-spoilage agents. The goal of the present study was to use the DNA sequences of the first three variable regions of the 165 rRNA gene, the 16S-23S rRNA internally transcribed spacer region sequence and approximately a third of the 60 kDa heat-shock protein gene to elucidate phylogenetic groupings within the genus Pediococcus. Phylogenetic trees were created with sequence data from 31 Pediococcus and three Lactobacillus isolates. Complete 16S rRNA gene sequences from selected Pediococcus isolates were also examined. The results were interpreted in relation to the currently accepted Pediococcus species. We found that, where previously done, speciation of many Pediococcus isolates is inaccurate. Also, one grouping of seven isolates did not include any currently recognized Pediococcus species type isolate. Our phylogenetic analyses support the conclusion that these seven isolates, all of brewing spoilage origin, belong to a novel species, for which the name Pediococcus claussenii sp. nov. is proposed (type strain P06(T0 = ATCC BAA-344(T) = DSM 14800(T)). Phylogenetic analysis has therefore helped to resolve problems surrounding species identification of Pediococcus isolates.


Assuntos
Pediococcus/classificação , Pediococcus/genética , Composição de Bases , Sequência de Bases , Cerveja/microbiologia , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/genética , Microbiologia de Alimentos , Dados de Sequência Molecular , Pediococcus/isolamento & purificação , Pediococcus/metabolismo , Fenótipo , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Especificidade da Espécie
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