Diversity of staphylococcal cassette chromosome mec structures in coagulase-negative staphylococci and relationship to drug resistance.
The objective of this study was to determine the distribution of staphylococcal cassette chromosome mec (SCCmec) elements in meticillin-resistant coagulase-negative staphylococci (MR-CoNS) isolated from a tertiary-care hospital in Mexico and to examine the relationship to drug resistance. Fifty selected MR-CoNS isolates collected from catheters (n=15), blood (n=15), bone (n=9), bronchial lavage (n=2) and urine (n=2) and one isolate each from an abscess, cerebrospinal fluid, eye, pleural effusion, synovial fluid, tracheal aspirate and wound secretion were examined. Susceptibility testing was performed by the broth microdilution method. SCCmec types were determined by multiplex PCR and PFGE was carried out as described previously for Staphylococcus aureus. Among the MR-CoNS strains studied, the most frequently isolated species were Staphylococcus epidermidis (n=26) and Staphylococcus haemolyticus (n=13). Staphylococcus cohnii (n=5), Staphylococcus hominis (n=3), Staphylococcus sciuri (n=1), Staphylococcus pasteuri (n=1) and the recently described species Staphylococcus pettenkoferi (n=1) were also identified. The most frequent MR-CoNS genotype identified was SCCmec type IVa in S. epidermidis isolates, which also showed a high diversity in their PFGE patterns. A clone was found that amplified both SCCmec III and V elements in five isolates examined. The single MR S. pettenkoferi isolate harboured SCCmec type IVd and the single MR S. pasteuri isolate harboured SCCmec type I. The carriage of SCCmec type III was associated with resistance or intermediate resistance to meropenem (P <0.05). These results confirm the high prevalence of S. epidermidis SCCmec IVa and the high genetic diversity among MR-CoNS strains. As far as is known, this is the first report describing the newly identified S. pettenkoferi possessing SCCmec IVd and S. pasteuri harbouring SCCmec type I. MR-CoNS harbouring SCCmec type III were found to be more resistant to meropenem.
Garza-González
Elvira
E
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
López
Daniel
D
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
Pezina
Cesar
C
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
Muruet
Walter
W
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
Bocanegra-García
Virgilio
V
Departamento de Biología Molecular y Bioingeniería, UAM Reynosa Aztlán, Universidad Autónoma de Tamaulipas, Tamaulipas, Mexico.
Muñoz
Ivan
I
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
Ramírez
Camilo
C
Departamento de Microbiología, Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
LLaca-Díaz
Jorge M
JM
Hospital Universitario Dr José Eleuterio González, Universidad Autónoma de Nuevo León, Monterrey Nuevo Leon 64460, Mexico.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002876:Chromosomes, Bacterial; D003030:Coagulase / Q000096:biosynthesis*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016106:Methicillin Resistance; D008800:Mexico; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D055815:Young Adult
D003030:Coagulase; D004269:DNA, Bacterial