Evaluation of phenotypic methods for methicillin resistance characterization in coagulase-negative staphylococci (CNS)

Caierão, Juliana; Musskopf, Maiara Isabel; Superti, Silvana; Roesch, Eliane Würdig; Dias, Cícero; d’Azevedo, Pedro Alves

doi:10.1099/jmm.0.45697-0

Cited by 22 publications

(23 citation statements)

References 18 publications

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“…This gene was located in a novel SSCmec designated type XI (10). Resistance to oxacillin, without the mecA gene, may be due to either the overproduction or overexpression of penicillinase or alteration of other penicillinbinding proteins (2). With respect to the SCCmec typing, the results are comparable to the distribution of the SCCmec types among S. haemolyticus strains that appeared to be major reservoirs of type V (13,16).…”

supporting

confidence: 72%

Staphylococcus haemolyticus as an Important Hospital Pathogen and Carrier of Methicillin Resistance Genes

et al. 2012

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Phenotypic and molecular methods were used to characterize the antibiotic resistance of 64 clinical isolates of Staphylococcus haemolyticus. By PCR of the mecA gene, 87% were found to be methicillin resistant. Approximately 55% harbored staphylococcal cassette chromosome mec element (SCCmec) type V, and only one SCCmec type IV. Many isolates (75%) displayed multiresistance, and pulsotype analysis showed a high diversity.A mong coagulase-negative staphylococci (CoNS), Staphylococcus haemolyticus is the second most frequently isolated from human blood cultures (18) and has the highest level of antimicrobial resistance (3,8). Methicillin resistance is conferred by the mecA gene, carried on the staphylococcal cassette chromosome mec element (SCCmec) (12). Eight types (I to VIII) of SCCmec have been assigned for Staphylococcus aureus (11), and SCCmec type V has already been found in CoNS, particularly in S. haemolyticus (13). The increase in the frequency of methicillinresistant S. haemolyticus as the causal agent of hospital infections and the possibility of emergence of resistance to other antibiotics demand trustworthy characterization of the isolates and an investigation of clonal spreading within hospitals.In the studies reported here, 64 clinical strains were isolated from patients at Hospital Naval Marcílio Dias, Rio de Janeiro, Brazil, between 2006 and 2008. The strains were isolated from the following clinical infections or sources in 31 males and 33 females: bacteremia (n ϭ 45), skin (n ϭ 2), urine (n ϭ 13), and unknown source (n ϭ 4). The isolates were identified at the hospital laboratory as S. haemolyticus by using the MicroScan WalkAway PC21 panel, and their identification was confirmed by specific PCR (17).The resistance profiles of the strains for the main antibiotics used in Brazil were determined by disc diffusion tests according to CLSI guidelines (5). However, the mupirocin susceptibility testing was not preconized by CLSI, so the results for this antibiotic were interpreted as previously described (7, 9). The methicillin resistance was also evaluated by other phenotypic methods, such as the MIC for oxacillin (5), the MicroScan, and PCR of the mecA gene (6). The SCCmec type was determined in a multiplex PCR as previously described (14), except that the pair of primers mecI P2 and mecI P3 used as the internal control were replaced by MRS1 and MRS2 (6), which amplify a 154-bp fragment of the mecA gene.Analysis of genetic relatedness and characterization of isolates using pulsed-field gel electrophoresis (PFGE) of genomic DNA digested with SmaI were carried out as previously described (20). Banding patterns were determined by visual inspection and by using Bionumerics software, version 6.0 (Applied Maths) using the Dice index and the unweighted-pair group method with arithmetic average. Similar PFGE genotypes were defined using a coefficient of similarity of up to 80%, and the subtypes were those with less than five-band variants, as recommended by van Belkun et al. (19).As shown in Table 1, there wa...

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confidence: 72%

Staphylococcus haemolyticus as an Important Hospital Pathogen and Carrier of Methicillin Resistance Genes

et al. 2012

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“…We evaluated a higher number of isolates of SCoNne than other studies performed in Brazil, and we found high rates of resistance to oxacillin by PCR (71%) in these isolates, though earlier studies also included isolates of S. epidermidis [26][27][28]. In our study, among the SCoNne isolates, 100 were identified as S. haemolyticus, with 91% presenting a mecAgene-positive PCR result.…”

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confidence: 37%

Identification and detection of methicillin resistance in Non-Epidermidis coagulase-negative staphylococci

Secchi¹,

Antunes²,

Perez³

et al. 2008

Braz J Infect Dis

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The NCCLS (2004) presented a new methodology to detect, by disk-diffusion agar, oxacillin-resistance using a cefoxitin disk. We identified coagulase-negative staphylococci (SCoN) to the species level and compared the use of cefoxitin disks (30 µ µ µ µ µg) with oxacillin disks (1 µ µ µ µ µg), agar dilution (minimum inhibitory concentration of oxacillin) and mecA gene detection in isolates of coagulase-negative bacteria other than Staphylococcus epidermidis (SCoNne). A total of 238 SCoNne was evaluated; oxacillin-resistance (the mecA gene) was detected in 71% of the isolates. All methods gave 100% sensitivity, based on presence of the mecA gene. The specificity of the cefoxitin disk was 100%, while the oxacillin disk gave a specificity of 91% and agar dilution oxacillin gave a specificity of 88%. We conclude that the cefoxitin disk is an efficient test, and it is an easy method for use in clinical laboratories to detect oxacillinresistance in staphylococci.

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“…Moreover, the resistance in S. epidermidis can be transferred to Staphylococcus aureus (15). mecA gene detection through PCR is the gold-standard method for detecting resistance to oxacillin in staphylococci [16]. Since hospital health-care staff are one of the major sources of infection transmission, the aim of this study was to evaluate the prevalence of slime formation, to detect the aap (as one of the major factors in biofilm formation) and mecA genes by molecular methods, as well as to characterize the relationship between slime production and antibiotic resistance in S. epidermidis from hospital workers.…”

Section: Introductionmentioning

confidence: 99%

Slime layer formation and the prevalence of mecA and aap genes in Staphylococcus epidermidis isolates

Pourmand

Abdossamadi

Salari

et al. 2010

J Infect Dev Ctries

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Introduction: Staphylococcus epidermidis strains are frequently associated with catheter-related infection, acute bacteremia, and hospitalacquired infection. Some isolates produce an extracellular matrix called slime that may make them more resistant to antibiotics. The aim of this study was to determine antimicrobial resistance patterns, the prevalence of slime production, and the distribution of genes (mecA and aap, respectively) associated with these phenotypes in S. epidermidis nasal isolates from health-care personnel. Methodology: A descriptive cross-sectional study was performed on 163 nasal swabs from health-care staff (one swab per subject). S. epidermidis isolates were tested for slime production on congo red agar and antibiotic resistance. PCR-based screening for mecA and aap genes was performed upon the extracted DNA of S. epidermidis isolates. Results: A total of 99 S. epidermidis strains were cultured from 58.9% of the study participants (n = 96). Of these strains, 34 (34.3%) isolates produced slime. A significant relation between slime production and resistance to penicillin 32(94%) , oxacillin 30(88%),, tetracycline 20(59%), erythromycin 27(79%), and clindamycin 26(77%) was found. Respectively, 95.8% and 94.8% of all isolates were PCR-positive for mecA and aap, but only 59.8% of mecA+ strains were oxacillin-resistant and 37.3% of aap+ strains were slime producers. Conclusions: The surveillance of nasal colonization with slime-forming oxacillin-resistant S. epidermidis in health-care workers might be helpful in breaking the epidemiological chain of hospital-acquired infections.

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Evaluation of phenotypic methods for methicillin resistance characterization in coagulase-negative staphylococci (CNS)

Cited by 22 publications

References 18 publications

Staphylococcus haemolyticus as an Important Hospital Pathogen and Carrier of Methicillin Resistance Genes

Staphylococcus haemolyticus as an Important Hospital Pathogen and Carrier of Methicillin Resistance Genes

Identification and detection of methicillin resistance in Non-Epidermidis coagulase-negative staphylococci

Slime layer formation and the prevalence of mecA and aap genes in Staphylococcus epidermidis isolates

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