Posts filed under ‘Resistencia bacteriana’

Understanding the Mechanism of Bacterial Biofilms Resistance to Antimicrobial Agents.

Open Microbiol J. 2017 Apr 28;11:53-62.

Singh S1, Singh SK2, Chowdhury I3, Singh R2.

1 Department of Kriya Sharir, Institute of Medical Sciences, Banaras Hindu University, Varanasi- 221 005 UP India.

2 Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, GA, USA.

3 Department of Obstetrics and Gynecology; Morehouse School of Medicine, Atlanta, GA, USA.

Abstract

A biofilm is a group of microorganisms, that causes health problems for the patients with indwelling medical devices via attachment of cells to the surface matrix. It increases the resistance of a microorganism for antimicrobial agents and developed the human infection. Current strategies are removed or prevent the microbial colonies from the medical devices, which are attached to the surfaces. This will improve the clinical outcomes in favor of the patients suffering from serious infectious diseases. Moreover, the identification and inhibition of genes, which have the major role in biofilm formation, could be the effective approach for health care systems. In a current review article, we are highlighting the biofilm matrix and molecular mechanism of antimicrobial resistance in bacterial biofilms.

PDF

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5427689/pdf/TOMICROJ-11-53.pdf

 

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October 14, 2018 at 10:44 am

Biofilms: survival mechanisms of clinically relevant microorganisms.

Clinical Microbiology Reviews April 2002 V.15 N.2 P.167-93.

Donlan RM1, Costerton JW.

1 Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. rld8@cdc.gov

Abstract

Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.

PDF

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC118068/pdf/0012.pdf

October 14, 2018 at 10:41 am

Biofilm formation: a clinically relevant microbiological process.

Clinical Infectious Disseases October 15, 2001 V.33 N.8 P.1387-92.

Donlan RM1.

1 Biofilm Laboratory, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. rld8@cdc.gov

Abstract

Microorganisms universally attach to surfaces and produce extracellular polysaccharides, resulting in the formation of a biofilm. Biofilms pose a serious problem for public health because of the increased resistance of biofilm-associated organisms to antimicrobial agents and the potential for these organisms to cause infections in patients with indwelling medical devices. An appreciation of the role of biofilms in infection should enhance the clinical decision-making process.

FULL TEXT

https://academic.oup.com/cid/article/33/8/1387/347551

PDF (CLIC en PDF)

 

October 14, 2018 at 10:39 am

Bacterial biofilms: resistance to antimicrobial agents.

Journal of Antimicrobial & Chemotherapy June 1996 V.37 N.6 P.1047-50.

Gander S1.

1 Department of Microbiology, Nottingham City Hospital, UK.

FULL TEXT

https://academic.oup.com/jac/article/37/6/1047/863249

PDF (CLIC en PDF)

October 14, 2018 at 10:36 am

Culture of Bone Biopsy Specimens Overestimates Rate of Residual Osteomyelitis After Toe or Forefoot Amputation.

J Bone Joint Surg Am. September 5, 2018 V.100 N.17 P.1448-1454.

Mijuskovic B1, Kuehl R1, Widmer AF1, Jundt G1, Frei R1, Gürke L1, Wolff T1.

Abstract

BACKGROUND:

Guidelines recommend both histological analysis and culture for definite diagnosis of osteomyelitis. It is not clear if histological and culture criteria can be used interchangeably in the clinical scenario of toe amputation. We therefore prospectively compared the results of intraoperative culture and those of histological examination in this setting.

METHODS:

Consecutive patients requiring toe or forefoot amputation at the University Hospital Basel during a 2-year period were included in the study. Biopsy specimens from the residual bone were cultured according to microbiological standards. Histological analysis was performed using standardized criteria for osteomyelitis. Clinical outcomes were assessed retrospectively via chart review.

RESULTS:

Of 51 patients included in the study, 33 (65%) had a positive culture of residual bone and 14 (27%) showed histological signs of osteomyelitis. A negative histological result but a positive culture was found for 21 (41%) of the patients, suggesting that culture has a high false-positive rate if histological analysis is used as the reference to rule out osteomyelitis. The recommended criteria of both positive histological findings and positive culture were fulfilled by 12 (24%) of the 51 patients.

CONCLUSIONS:

Positive cultures of residual bone after forefoot or toe amputation overestimate the true rate of osteomyelitis as defined by histological analysis, presumably because of contamination from soft tissue at the time of surgery. Additional studies are needed to evaluate the indications for, and the duration of, antibiotic treatment according to these findings.

CLINICAL RELEVANCE:

Our results cast doubt on the strategy of relying solely on culture of bone biopsy specimens when deciding whether antibiotic treatment for osteomyelitis is necessary after toe or forefoot amputation.

PDF

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6125752/pdf/jbjsam-100-1448.pdf

 

October 11, 2018 at 8:15 am

Control of a multi-hospital outbreak of KPC-producing Klebsiella pneumoniae type 2 in France, September to October 2009.

Euro Surveill. December 2, 2010 V.15 N.48. pii: 19734.

Carbonne A1, Thiolet JM, Fournier S, Fortineau N, Kassis-Chikhani N, Boytchev I, Aggoune M, Seguier JC, Senechal H, Tavolacci MP, Coignard B, Astagneau P, Jarlier V.

Abstract

An outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae type 2 was detected in September 2009 in two hospitals in a suburb south of Paris, France. In total, 13 KPC-producing K. pneumoniae type 2 cases (four with infections and nine with digestive-tract colonisations) were identified, including a source case transferred from a Greek hospital. Of the 13 cases, seven were secondary cases associated with use of a contaminated duodenoscope used to examine the source case (attack rate: 41%) and five were secondary cases associated with patient-to-patient transmission in hospital. All isolated strains from the 13 patients: (i) exhibited resistance to all antibiotics except gentamicin and colistin, (ii) were more resistant to ertapenem (minimum inhibitory concentration (MIC) always greater than 4 mg/L) than to imipenem (MIC: 1–8 mg/L, depending on the isolate), (iii) carried the blaKPC-2 and blaSHV12 genes and (iv) had an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern. These cases occurred in three hospitals: some were transferred to four other hospitals. Extended infection control measures implemented in the seven hospitals included: (i) limiting transfer of cases and contact patients to other wards, (ii) cohorting separately cases and contact patients, (iii) reinforcing hand hygiene and contact precautions and (iv) systematic screening of contact patients. Overall, 341 contact patients were screened. A year after the outbreak, no additional case has been identified in these seven hospitals. This outbreak emphasises the importance of rapid identification and notification of emerging highly resistant K. pneumoniae strains in order to implement reinforced control measures

FULL TEXT

https://www.eurosurveillance.org/content/10.2807/ese.15.48.19734-en

October 10, 2018 at 1:00 pm

Genomic Epidemiology of an Endoscope-Associated Outbreak of Klebsiella pneumoniae Carbapenemase (KPC)-Producing K. pneumoniae.

PLoS One. December 4, 2015 V.10 N.12 P.e0144310.

Marsh JW1, Krauland MG1,2, Nelson JS1, Schlackman JL1, Brooks AM1, Pasculle AW3, Shutt KA1, Doi Y4, Querry AM5, Muto CA1,5, Harrison LH1.

Abstract

Increased incidence of infections due to Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp) was noted among patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) at a single hospital. An epidemiologic investigation identified KPC-Kp and non-KPC-producing, extended-spectrum β-lactamase (ESBL)-producing Kp in cultures from 2 endoscopes. Genotyping was performed on patient and endoscope isolates to characterize the microbial genomics of the outbreak. Genetic similarity of 51 Kp isolates from 37 patients and 3 endoscopes was assessed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Five patient and 2 endoscope isolates underwent whole genome sequencing (WGS). Two KPC-encoding plasmids were characterized by single molecule, real-time sequencing. Plasmid diversity was assessed by endonuclease digestion. Genomic and epidemiologic data were used in conjunction to investigate the outbreak source. Two clusters of Kp patient isolates were genetically related to endoscope isolates by PFGE. A subset of patient isolates were collected post-ERCP, suggesting ERCP endoscopes as a possible source. A phylogeny of 7 Kp genomes from patient and endoscope isolates supported ERCP as a potential source of transmission. Differences in gene content defined 5 ST258 subclades and identified 2 of the subclades as outbreak-associated. A novel KPC-encoding plasmid, pKp28 helped define and track one endoscope-associated ST258 subclade. WGS demonstrated high genetic relatedness of patient and ERCP endoscope isolates suggesting ERCP-associated transmission of ST258 KPC-Kp. Gene and plasmid content discriminated the outbreak from endemic ST258 populations and assisted with the molecular epidemiologic investigation of an extended KPC-Kp outbreak.

PDF

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4670079/pdf/pone.0144310.pdf

October 10, 2018 at 12:57 pm

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