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Edlund, Charlotta
Publications (10 of 28) Show all publications
Jernberg, C., Löfmark, S., Edlund, C. & Jansson, J. K. (2007). Long-term ecological impacts of antibiotic administration on the human intestinal microbiota. The ISME Journal, 1(1), 56-66
Open this publication in new window or tab >>Long-term ecological impacts of antibiotic administration on the human intestinal microbiota
2007 (English)In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 1, no 1, p. 56-66Article in journal (Refereed) Published
Abstract [en]

Antibiotic administration is known to cause short-term disturbances in the microbiota of the human gastrointestinal tract, but the potential long-term consequences have not been well studied. The aims of this study were to analyse the long-term impact of a 7-day clindamycin treatment on the faecal microbiota and to simultaneously monitor the ecological stability of the microbiota in a control group as a baseline for reference. Faecal samples from four clindamycin-exposed and four control subjects were collected at nine different time points over 2 years. Using a polyphasic approach, we observed highly significant disturbances in the bacterial community that persisted throughout the sampling period. In particular, a sharp decline in the clonal diversity of Bacteroides isolates, as assessed by repetitive sequence-based PCR (rep-PCR) and long-term persistence of highly resistant clones were found as a direct response to the antibiotic exposure. The Bacteroides community never returned to its original composition during the study period as assessed using the molecular fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). Furthermore, using real-time PCR we found a dramatic and persistent increase in levels of specific resistance genes in DNA extracted from the faeces after clindamycin administration. The temporal variations in the microbiota of the control group were minor compared to the large and persistent shift seen in the exposed group. These results demonstrate that long after the selection pressure from a short antibiotic exposure has been removed, there are still persistent long term impacts on the human intestinal microbiota that remain for up to 2 years post-treatment.

Keywords
Bacteroides, clindamycin, rep-PCR, faeces, T-RFLP
National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-31968 (URN)10.1038/ismej.2007.3 (DOI)000249215800009 ()18043614 (PubMedID)2-s2.0-34248152283 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Erratum: Jernberg, C., Löfmark, S., Edlund, C., & Jansson, J. K. (2013). Erratum: Long-term ecological impacts of antibiotic administration on the human intestinal microbiota (ISME journal (2007) 1 (56-66) DOI: 10.1038/ismej.2007.3). ISME Journal, 7(2), 456. doi:10.1038/ismej.2012.91

Available from: 2017-02-07 Created: 2017-02-06 Last updated: 2017-11-29Bibliographically approved
diva2:468822
Open this publication in new window or tab >>Clindamycin-induced enrichment and long-term persistence of resistant Bacteroides spp. and resistance genes
2006 (English)In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 58, no 6, p. 1160-1167Article in journal (Refereed) Published
Abstract [en]

Objectives: The aim was to study the long-term consequences of 1 week clindamycin administration regarding selection and persistence of resistance, resistance determinants and diversity of the Bacteroides spp. in the intestinal microflora. Methods: A total of 1306 Bacteroides isolates were collected from constitutively cultured faecal samples during a 2 year period from eight healthy volunteers. The strains were identified by biochemical and genotyping methods. MIC values were determined by the agar dilution method and presence of resistance genes was screened by real-time PCR. Results: Ecological changes in the intestinal microflora persisting up to 24 months were recorded after a 7 day clindamycin administration to four healthy volunteers. Compared to a control group, not exposed to clindamycin, an enrichment and stabilization of resistant Bacteroides strains and resistance determinants were discovered up to 2 years after clindamycin exposure. Conclusions: The results indicate that even a short-term antibiotic administration can cause long-term alterations in the commensal microbiota of individual subjects, detectable 2 years after dosing. The recorded selection and persistence of resistant strains and resistance genes, illustrates the importance of increasing our knowledge of the role of the abundant intestinal microbial community as a reservoir for spread of resistance.

National Category
Microbiology Pharmacology and Toxicology Pharmaceutical Sciences
Identifiers
urn:nbn:se:sh:diva-14266 (URN)10.1093/jac/dkl420 (DOI)000242716600009 ()17046967 (PubMedID)2-s2.0-33845349674 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-21 Created: 2011-12-20 Last updated: 2018-01-12Bibliographically approved
Lund, B., Billström, H. & Edlund, C. (2006). Increased conjugation frequencies in clinical Enterococcus faecium strains harbouring the enterococcal surface protein gene esp. Clinical Microbiology and Infection, 12(6), 588-591
Open this publication in new window or tab >>Increased conjugation frequencies in clinical Enterococcus faecium strains harbouring the enterococcal surface protein gene esp
2006 (English)In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 12, no 6, p. 588-591Article in journal (Refereed) Published
Abstract [en]

This study compared the in-vitro ability of Enterococcus faecium isolates of different origin to acquire vanA by conjugation in relation to the occurrence of the esp gene. In total, 29 clinical isolates (15/29 esp+), 30 normal intestinal microflora isolates (2/30 esp+) and one probiotic strain (esp-) were studied with a filter-mating assay. Conjugation events were confirmed by PCR and pulsed-field gel electrophoresis. Among the infection-derived isolates, the esp+ isolates had higher conjugation frequencies compared with esp- isolates (p < 0.001), with a median value of 6.4 x 10(-6) transconjugants/donor. The probiotic strain was shown to acquire vanA vancomycin resistance in in-vitro filter mating experiments.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-14298 (URN)10.1111/j.1469-0691.2006.01436.x (DOI)000237515600017 ()16700712 (PubMedID)2-s2.0-33646702110 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-20 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
Löfmark, S., Fang, H., Hedberg, M. & Edlund, C. (2005). Inducible metronidazole resistance and nim genes in clinical Bacteroides fragilis group isolates. Antimicrobial Agents and Chemotherapy, 49(3), 1253-1256
Open this publication in new window or tab >>Inducible metronidazole resistance and nim genes in clinical Bacteroides fragilis group isolates
2005 (English)In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 49, no 3, p. 1253-1256Article in journal (Refereed) Published
Abstract [en]

Nitroimidazole resistance (nim) genes were detected in 2% of 1,502 clinical Bacteroides fragilis group strains isolated from 19 European countries, and a novel nim gene was identified. High metronidazole resistance could be induced in nim-positive strains, which emphasizes the importance of acknowledging metronidazole resistance in the clinical setting.

National Category
Microbiology Pharmacology and Toxicology
Identifiers
urn:nbn:se:sh:diva-14390 (URN)10.1128/AAC.49.3.1253-1256.2005 (DOI)000227339500066 ()15728943 (PubMedID)2-s2.0-14744271290 (Scopus ID)
Available from: 2011-12-22 Created: 2011-12-21 Last updated: 2018-01-12Bibliographically approved
Jernberg, C., Sullivan, A., Edlund, C. & Jansson, J. K. (2005). Monitoring of antibiotic-induced alterations in the human intestinal microflora and detection of probiotic strains by use of terminal restriction fragment length polymorphism. Applied and Environmental Microbiology, 71(1), 501-506
Open this publication in new window or tab >>Monitoring of antibiotic-induced alterations in the human intestinal microflora and detection of probiotic strains by use of terminal restriction fragment length polymorphism
2005 (English)In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 71, no 1, p. 501-506Article in journal (Refereed) Published
Abstract [en]

Terminal restriction fragment length polymorphism (T-RFLP) was investigated as a tool for monitoring the human intestinal microflora during antibiotic treatment and during ingestion of a probiotic product. Fecal samples from eight healthy volunteers were taken before, during, and after administration of clindamycin. During treatment, four subjects were given a probiotic, and four subjects were given a placebo. Changes in the microbial intestinal community composition and relative abundance of specific microbial populations in each subject were monitored by using viable counts and T-RFLP fingerprints. T-RFLP was also used to monitor specific bacterial populations that were either positively or negatively affected by clindamycin. Some dominant bacterial groups, such as Eubacterium spp., were easily monitored by T-RFLP, while they were hard to recover by cultivation. Furthermore, the two probiotic Lactobacillus strains were easily tracked by T-RFLP and were shown to be the dominant Lactobacillus community members in the intestinal microflora of subjects who received the probiotic.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-17365 (URN)10.1128/AEM.71.1.501-506.2005 (DOI)000226458800062 ()15640226 (PubMedID)2-s2.0-12244292700 (Scopus ID)
Available from: 2012-11-22 Created: 2012-11-19 Last updated: 2017-07-19Bibliographically approved
Agvald-Öhman, C., Lund, B. & Edlund, C. (2004). Multiresistant coagulase-negative staphylococci disseminate frequently between intubated patients in a multidisciplinary intensive care unit. Critical Care, 8(1), R42-R47
Open this publication in new window or tab >>Multiresistant coagulase-negative staphylococci disseminate frequently between intubated patients in a multidisciplinary intensive care unit
2004 (English)In: Critical Care, ISSN 1364-8535, E-ISSN 1466-609X, Vol. 8, no 1, p. R42-R47Article in journal (Refereed) Published
Abstract [en]

Introduction The intensive care unit is burdened with a high frequency of nosocomial infections often caused by multiresistant nosocomial pathogens. Coagulase-negative staphylococci (CoNS) are reported to be the third causative agent of nosocomial infections and the most frequent cause of nosocomial bloodstream infections. CoNS are a part of the normal microflora of skin but can also colonize the nasal mucosa, the lower airways and invasive devices. The main aim of the present study was to investigate colonization and the rate of cross-transmissions of CoNS between intubated patients in a multidisciplinary intensive care unit. Materials and methods Twenty consecutive patients, ventilated for at least 3 days, were included. Samples were collected from the upper and lower airways. All samples were cultured quantitatively and CoNS were identified by morphology and biochemical tests. A total of 199 CoNS isolates from 17 patients were genetically fingerprinted by pulsed-field gel electrophoresis in order to identify clones and to monitor dissemination within and between patients. Results An unexpected high number of transmission events were detected. Five genotypes were each isolated from two or more patients, and 14/20 patients were involved in at least one and up to eight probable transmission events. Conclusions A frequent transmission of CoNS was found between patients in the intensive care unit. Although transmission of bacteria does not necessarily lead to infection, it is nevertheless an indication that infection control measures can be improved.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:sh:diva-15496 (URN)10.1186/cc2422 (DOI)000188720100006 ()14975054 (PubMedID)
Available from: 2012-02-20 Created: 2012-02-20 Last updated: 2017-07-19Bibliographically approved
Agvald-Öhman, C., Wernerman, J., Nord, C. E. & Edlund, C. (2003). Anaerobic bacteria commonly colonize the lower airways of intubated ICU patients. Clinical Microbiology and Infection, 9(5), 397-405
Open this publication in new window or tab >>Anaerobic bacteria commonly colonize the lower airways of intubated ICU patients
2003 (English)In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 9, no 5, p. 397-405Article in journal (Refereed) Published
Abstract [en]

Objectives To investigate respiratory tract colonization by aerobic and anaerobic bacteria in mechanically ventilated patients. Methods Bacterial colonization of the stomach and the respiratory tract was qualitatively and quantitatively analyzed over time in 41 consecutive mechanically ventilated patients in a Swedish intensive care unit (ICU), with special emphasis on elucidation of the role of anaerobic bacteria in the lower respiratory tract. Samples were taken from the oropharynx, gastric juice, subglottic space and trachea within 24 h (median 14 h) of intubation, and then every third day until day 18 and every fifth day until day 33. Results The patients were often heavily colonized with microorganisms not considered to belong to a healthy normal oropharyngeal and gastric flora on admission to the ICU. A majority harbored enterococci, coagulase-negative staphylococci and Candida spp. in at least one site on day 1. Anaerobic bacteria, mainly peptostreptococci and Prevotella spp., were isolated from subglottic and/or tracheal secretions in 59% of the patients. Different routes of tracheal colonization for different groups of microorganisms were found. Primary or concomitant colonization of the oropharynx with staphylococci, enterococci, enterobacteria and Candida was often seen, while Pseudomonas spp., other non-fermenting Gram-negative rods and several anaerobic species often primarily colonized the trachea, indicating exogenous or direct gastrointestinal routes of colonization. Conclusions Mechanically ventilated patients were heavily colonized in their lower airways by potential pathogenic microorganisms, including a high load of anaerobic bacteria. Different routes of colonization were shown for different species.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15543 (URN)10.1046/j.1469-0691.2003.00551.x (DOI)000182726300008 ()12848752 (PubMedID)2-s2.0-0038546776 (Scopus ID)
Available from: 2012-02-21 Created: 2012-02-21 Last updated: 2017-12-07Bibliographically approved
Lund, B. & Edlund, C. (2003). Bloodstream isolates of Enterococcus faecium enriched with the enterococcal surface protein gene, esp, show increased adhesion to eukaryotic cells. Journal of Clinical Microbiology, 41(11), 5183-5185
Open this publication in new window or tab >>Bloodstream isolates of Enterococcus faecium enriched with the enterococcal surface protein gene, esp, show increased adhesion to eukaryotic cells
2003 (English)In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 41, no 11, p. 5183-5185Article in journal (Refereed) Published
Abstract [en]

Infection-derived Enterococcus faecium strains enriched with esp had increased ability to adhere to Caco-2 cells (P < 0.05) and were less genetically diverse than esp-negative isolates. esp-negative E. faecium fecal isolates from healthy individuals adhered significantly better than esp-negative infection isolates (P < 0.05), indicating additional factors of importance to adhesion.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15524 (URN)10.1128/JCM.41.11.5183-5185.2003 (DOI)000186665500040 ()14605157 (PubMedID)2-s2.0-0242593799 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation, with title:

Increased adhesion to eukaryotic cells in Enterococcus faecium bloodstream isolates enriched with enterococcal surface protein gene, esp

Available from: 2012-02-21 Created: 2012-02-21 Last updated: 2017-07-19Bibliographically approved
Oh, H. & Edlund, C. (2003). Mechanism of quinolone resistance in anaerobic bacteria. Clinical Microbiology and Infection, 9(6), 512-517
Open this publication in new window or tab >>Mechanism of quinolone resistance in anaerobic bacteria
2003 (English)In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 9, no 6, p. 512-517Article in journal (Refereed) Published
Abstract [en]

Several recently developed quinolones have excellent activity against a broad range of aerobic and anaerobic bacteria and are thus potential drugs for the treatment of serious anaerobic and mixed infections. Resistance to quinolones is increasing worldwide, but is still relatively infrequent among anaerobes. Two main mechanisms, alteration of target enzymes (gyrase and topoisomerase IV) caused by chromosomal mutations in encoding genes, or reduced intracellular accumulation due to increased efflux of the drug, are associated with quinolone resistance. These mechanisms have also been found in anaerobic species. High-level resistance to the newer broad-spectrum quinolones often requires stepwise mutations in target genes. The increasing emergence of resistance among anaerobes may be a consequence of previous widespread use of quinolones, which may have enriched first-step mutants in the intestinal tract. Quinolone resistance in the Bacteroides fragilis group strains is strongly correlated with amino acid substitutions at positions 82 and 86 in GyrA (equivalent to positions 83 and 87 of Escherichia coli ). Several studies have indicated that B. fragilis group strains possess efflux pump systems that actively expel quinolones, leading to resistance. DNA gyrase seems also to be the primary target for quinolones in Clostridium difficile , since amino acid substitutions in GyrA and GyrB have been detected in resistant strains. To what extent other mechanisms, such as mutational events in other target genes or alterations in outer-membrane proteins, contribute to resistance among anaerobes needs to be further investigated.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15542 (URN)10.1046/j.1469-0691.2003.00725.x (DOI)000183731200006 ()
Available from: 2012-02-21 Created: 2012-02-21 Last updated: 2017-12-07Bibliographically approved
Fang, H., Edlund, C., Hultenby, K. & Hedberg, M. (2002). Effects of cefoxitin on the growth and morphology of Bacteroides thetaiotaomicron strains with different cefoxitin susceptibility. Anaerobe, 8(2), 55-61
Open this publication in new window or tab >>Effects of cefoxitin on the growth and morphology of Bacteroides thetaiotaomicron strains with different cefoxitin susceptibility
2002 (English)In: Anaerobe, ISSN 1075-9964, E-ISSN 1095-8274, Vol. 8, no 2, p. 55-61Article in journal (Refereed) Published
Abstract [en]

To examine the effects of cefoxitin on bacterial growth and cell morphology, two pairs of Bacteroides thetaiotaomicron strains (238, 238 m and 1186, 1186 m) with different susceptibilities to this antibiotic were investigated in the present study. B. thetaiotaomicron 238m and 1186m were resistant laboratory mutants originating from the susceptible wild-type strains B. thetaiotaomicron 238 and 1186, respectively. It has been shown, in a previous study, that the mutant strains had alterations in their penicillin-binding proteins (PBPs) as compared to the parent strains. In the present study, strains 238 and 238m presented almost identical genomic fingerprints by PCR, so did strains 1186 and 1186m, which indicates that the parent and mutant strains have similar genomic background. In comparison with the parent strains, the growth rate of mutant strains was slower in cultures without antibiotic. The growth patterns challenged with cefoxitin were also different between the parent and the mutant strains. In case of the morphological responses to cefoxitin, the mutant strains were more resistant to the effect of cefoxitin than the parent strains. In conclusion, the growth patterns and the morphological changes induced by cefoxitin, of the investigated strains, were associated with the properties of PBPs. The resistant mutants with deficiency in PBPs grew slower than the susceptible parent strains, and cefoxitin caused filamentation at sub-MIC in B. thetaiotaomicron.

National Category
Microbiology
Identifiers
urn:nbn:se:sh:diva-15810 (URN)10.1006/anae.2002.0417 (DOI)000177881500002 ()2-s2.0-0036547547 (Scopus ID)
Available from: 2012-03-08 Created: 2012-03-07 Last updated: 2017-12-07Bibliographically approved
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