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Fabíola Menegotto, Sandra Gonzáles-Cabrero, Belén Lorenzo, África Cubero,
Williams Cuervo, María Purificación Gutiérrez, María Simarro, Antonio Orduña,
Miguel Ángel Bratos
MOLECULAR EPIDEMIOLOGY OF METHICILLIN-RESISTANT
STAPHYLOCOCCUS AUREUS IN SPANISH HOSPITAL OVER A 4-YEAR PERIOD: CLONAL REPLACEMENT, DECREASED ANTIMICROBIAL RESISTANCE, AND IDENTIFICATION OF COMMUNITY-
ACQUIRED AND LIVESTOCK-ASSOCIATED CLONES
POR: Nataly Giraldo Camila Jaramillo
INTRODUCTION
Genus: StaphylococcusGram-positive cocciCatalase-positive It catalyzes the decomposition of hydrogen peroxide to water and oxygen
facultative anaerobe
ImmobileThey grows fast
without oxygen
with oxygen
INTRODUCTION Staphylococcus don´t release spores They are resistant to adverse environmental
conditions They are part of the normal microbial flora skin
and mucous in humans
INTRODUCTION
Species: aureusCoagulase-positive is a protein that enables the conversion of fibrinogen to fibrinThey are heat resistant microorganisms Most strains coated by
protein A
INTRODUCTION Some strains may have mucoide capsule,
called slime To increase its adherence ability and antiphagocytic effect
The peptidoglycan is about 50% by weight of cell wall
Colonies are smooth and bright
INTRODUCTION
METHICILLIN:
Is a β-lactam antibiotic used in the treatment of bacterial infections caused by organisms of the genus Staphylococcus. It acts by inhibiting penicillin-binding proteins (PBPs) that are involved in the synthesis of peptidoglycan, an essential mesh-like polymer that surrounds the cell.
INTRODUCTION
Methicillin required administration via intramuscular or intravenous injection because it was inactivated by gastric acid in the stomach when taken orally
INTRODUCTION
RESISTANTIs a form of drug resistance whereby some microorganism are able to survive exposure to one or more antibiotics. There are 3 types of bacterial resistance:
NATURAL RESISTANCE Generated by different strain mechanism, independent of antibiotic exposure
ENVIRONMENTAL RESISTANCE
Generated by exposure to physical and chemical factors
ACQUIRED RESISTANCE
Generated by changes in bacterial genome over time
Is resistant to the action of methicillin
INTRODUCTIONBACTERIAL RESISTANC
E
Depends on its ability to mutate and transfer of genetic
information
Staphylococcus aureus
can become resistant to methicillin and other β-lactam antibiotics
through
the expression of a foreign PBP: PBP2a
that
making the treatment more difficult and limited
OVERALL OBJECTIVE
“Identify the changes in molecular epidemiology
of methicillin-resistant Staphylococcus aureus
(MRSA) isolates from Spanish third-level hospital
between 2005 and 2008, and to correlate the
changes in antibiotic resistance profiles (RPs)
with the clonal nature of MRSA in our institution”
MATERIALES Y MÉTODOS
MUESTRAS CLÍNICAS:189 MRSA sin repetir fueron obtenidas de muestras clínicas recolectadas en 2005, 2007 y 2008 en el Hospital Clínico Universitario Valladolid, España
105 de pacientes con infecciones en tejidos blandos y piel
2 por bacteriemia
37 por infección de puntos quirúrgicos
1 por infección del aparato auditivo
39 por infección del tracto respiratorio
1 de infección del tracto urinario
4 de huesos y articulaciones infectadas
MATERIALES Y MÉTODOS
EXAMEN DE SUSCEPTIBILIDAD ANTIMICROBIANAUTILIDA
D
Para determinar si un microorganismo, como el Staphylococcus aureus es sensible, intermedio o resistente a un agente antimicrobiano.
Elegir el tratamiento mas efectivo
contra la bacteria
MATERIALES Y MÉTODOS
EXAMEN DE SUSCEPTIBILIDAD ANTIMICROBIANA
MIC (concentración mínima inhibitoria):Tubo con la menor concentración de antibiótico que ha inhibido la bacteria.
Método de dilución de caldo: Muller HintonMedio preferido para pruebas de susceptibilidad de organismos comúnmente aislados, aeróbicos o facultativos de rápido crecimiento.
MATERIALES Y MÉTODOS
EXAMEN DE SUSCEPTIBILIDAD ANTIMICROBIANA
15 agentes antimicrobianos diferentes fueron diluidos en serie en caldo Muller-Hinton con suplementación de Ca+2 y Mg.
Ciorofloxacina ,eritromicina ,tobramicina, gentamicina, mupirocina, ácido fusídico, cloranfenicol, tetraciclina, rifampicina, trimetoprima/sulfametoxazol, teicoplanina, linezolida, daptomicina y vancomicina
MATERIALES Y MÉTODOS El MIC fue determinado al observar la
menor concentración antimicrobial mostrando inhibición o crecimiento.
La resistencia a la clindamicina también se detectó usando test de aproximación de disco.
MATERIALES Y MÉTODOS
TIPIFICACIÓN DE SCCmec Y ccrABC:
PCR MÚLTIPLE: «Reacciones que consiguen
amplificar simultáneamente y, en un único
tubo, diferentes secuencias diana,
permitiendo la detección e identificación
simultánea de distintos genes de interés…»
MATERIALES Y MÉTODOS
TIPIFICACIÓN DE SCCmec Y ccrABC:
La detección de genes de recombinación
(ccrA, ccrB, ccrC) en el elemento de SCCmec
fueron realizadas por hibridación a un
conjunto de sondas en una matriz de DNA.
MATERIALES Y MÉTODOS
TIPIFICACIÓN DE SECUENCIAS MULTILOCUS (MLST) Y spa:
MLST: Es una técnica para la
caracterización taxonómica de bacterias y
microorganismos. Compara las secuencias
de nucleótidos directamente entre las cepas.
MATERIALES Y MÉTODOS
El software Ridom SraphType, versión 1.4,
fue usado para el análisis de los tipos de spa,
y los tipos de secuencia (STs) donde fueron
asignados por medio de la base de datos
MLST. Por aplicación del algoritmo
goelBURST, los ST’s se agruparon en
complejos clonales diferentes.
RESULTADOS Aislados 189
STs identificados
91% agrupados en: t067 (49.7%)t109 (18.5%)t002 (13.2%)t008 (6.3%)t1391 (2.6%)
ST2422ST125ST5ST146ST228ST45ST8ST239ST97
NUEVO
Complejos clonales:CC5, CC8, C45, CC97 y CC121
RESULTADOS
SEPA 2005 2007 2008
ST228 54% 14% 14%
ST125ST146
32%11%
54%11%
55%21%
ST125-IV/VI Resistentes a eritromicina y ciproflaxina+tobramicinaST125IV Susceptibles a eritromicina
DISCUSSIONAUTHOR OPNION AGREE OR
DESAGREE
M. Perez-Vazquez, A. Vindel, C. Marcos, J. Oteo, O. Cuevas, P. Trincado
“In these studies, it was revealed that the ST125-MRSA-IV clone is currently the most prevalent in Spain.”
M.L. Amorim, N.A. Faria, D.C. Oliveira, C. Vasconcelos, J.C. Cabeda and A.C. Mendes
“Increase of infections caused by nonmultiresistant MRSA carrying SCCmec IV in healthcare institutions was observed”
DISCUSSIONAUTHOR OPINION AGREE OR
DESAGREE
E.B. Nannini, E. Murray and C.A. Arias
“Worldwide, there are increasing numbers of reports regarding heterogeneous vancomycin-intermediate S. aureus”
Cuny, F. Layer, B. Strommenger, and W. Witte
“Similar ST130 strains have been isolated from human infection in the UK, Denmark, and Germany at low frequency”
PERSONAL CONCLUSION
It is very important this type of study, because they show the dynamics of
transformation over time MRSA strains that are causing infections of varying
severity
PERSONAL CONCLUSION
Studies like this should be done more
frequently to study the possible risks of
infection in hospital environments
Tracking most frequent bacterial strains in
each region allows determine its ability to
spread from one region to another
PERSONAL CONCLUSION
Bacterial resistance to antibiotics should
be considered a global emergency,
because there are less effective
antibiotics to infections treatment.
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