title: Vancomycin tolerant, methicillin-resistant Staphylococcus aureus reveals the effects of vancomycin on cell wall thickening.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is an important opportunistic pathogen that causes both healthcare- and community-acquired infections. An increase in the incidence of these infections may lead to a substantial change in the rate of vancomycin usage. Incidence of reduced susceptibility to vancomycin has been increasing worldwide for the last few years, conferring different levels of resistance to vancomycin as well as producing changes in the cell wall structure. The aim of the present study was to determine the effect of vancomycin on cell wall thickening in clinical isolates of vancomycin-tolerant (VT) MRSA obtained from pediatric patients. From a collection of 100 MRSA clinical isolates from pediatric patients, 12% (12/100) were characterized as VT-MRSA, and from them, 41.66% (5/12) exhibited the heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotype. Multiplex-PCR assays revealed 66.66% (8/12), 25% (3/12), and 8.33% (1/12) of the VT-MRSA isolates were associated with agr group II, I, and III polymorphisms, respectively; the II-mec gene was amplified from 83.3% (10/12) of the isolates, and the mecIVa gene was amplified from 16.66% (2/12) of the isolates. Pulsed field electrophoresis (PFGE) fingerprint analysis showed 62% similarity among the VT-MRSA isolates. Thin transverse sections analyzed by transmission electron microscopy (TEM) revealed an average increase of 24 nm (105.55%) in the cell wall thickness of VT-MRSA compared with untreated VT-MRSA isolates. In summary, these data revealed that the thickened cell walls of VT-MRSA clinical isolates with agr type II and SCCmec group II polymorphisms are associated with an adaptive resistance to vancomycin.
authors: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Vicenta
authors: V
authors: Cázares-Domínguez
authors: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Ariadnna
authors: A
authors: Cruz-Córdova
authors: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Sara A
authors: SA
authors: Ochoa
authors: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Gerardo
authors: G
authors: Escalona
authors: Departamento de Infectología, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: José
authors: J
authors: Arellano-Galindo
authors: Laboratorio de Patología, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Alejandra
authors: A
authors: Rodríguez-Leviz
authors: Departamento de Ecología de Agentes Patógenos. Hospital General "Dr. Manuel Gea González", Delegación Tlalpan, México D.F., México.
authors: Rigoberto
authors: R
authors: Hernández-Castro
authors: Laboratorio Central de Microscopia. Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. Prol. De Carpio y Plan de Ayala S/N Col. Santo Tomás, Delegación Miguel Hidalgo, México D.F., México.
authors: Edgar O
authors: EO
authors: López-Villegas
authors: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez, Dr. Márquez 162, Col. Doctores, Delegación Cuauhtémoc, México D.F., México.
authors: Juan
authors: J
authors: Xicohtencatl-Cortes
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D002473:Cell Wall / Q000187:drug effects*; D002648:Child; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology; D004352:Drug Resistance, Microbial / Q000187:drug effects; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000166:cytology* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D010802:Phylogeny; D011110:Polymorphism, Genetic; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D014640:Vancomycin