Methicillin-resistant staphylococci: detection methods and treatment of infections

Hackbarth, C J; Chambers, Henry F.

doi:10.1128/aac.33.7.995

Cited by 113 publications

(73 citation statements)

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“…Maybe the in vivo expression of the mec A gene in CONS is low as opposed to the high in vitro expression in standardized susceptibility testing, which is designed to maximally facilitate expression of the mec A gene. 22 The 85% concordance between Vitek oxacillin susceptibility results and mec A gene carriage is in agreement with the 80% concordance found in a recently published French study. 23 Thus, one could argue that possibly in vitro testing is not relevant for the clinical situation in which transcription of the mec A gene may be suppressed or switched off, for example by phase variation, as described by Mempel and associates.…”

Section: Discussionsupporting

confidence: 80%

“…23 Thus, one could argue that possibly in vitro testing is not relevant for the clinical situation in which transcription of the mec A gene may be suppressed or switched off, for example by phase variation, as described by Mempel and associates. 24 Alternatively, even when mec A is expressed in vivo, it is not unlikely that this expression is strongly heterogeneous, 9,22 and cephalothin treatment possibly still will result in substantial growth inhibition or even killing of the staphylococcal cells not expressing oxacillin resistance. Subsequently, the patient's host defenses, although immature, may be capable of clearing the relatively small subpopulation of bacteria that fully expresses mec A and thus oxacillin and cephalothin resistance, and that therefore escapes antibiotic-induced killing.…”

Section: Discussionmentioning

confidence: 99%

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Clinical Outcome of Cephalothin Versus Vancomycin Therapy in the Treatment of Coagulase-negative Staphylococcal Septicemia in Neonates: Relation to Methicillin Resistance and mec A Gene Carriage of Blood Isolates

Krediet¹,

Jones

Gerards³

et al. 1999

Pediatrics

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ABSTRACT. Objective. Coagulase-negative staphylococci (CONS) are the most common causative agents in neonatal nosocomial septicemia. Because of widespread methicillin resistance among CONS, empiric therapy with vancomycin is recommended as the primary antibiotic regimen for these infections. In our unit, empiric treatment of nosocomially acquired septicemia consists of cephalothin and gentamicin, which are adjusted subsequently according to the determined bacterial susceptibility profile. Vancomycin is initiated only when the patient has been treated recently with cephalothin or when intravascular lines or endotracheal tube are colonized with oxacillin/cephalothin-resistant CONS strains. The aim of the present study was to evaluate the efficacy of our antibiotic regimen for CONS septicemia, in relation to methicillin-resistance and the carriage of mec A gene, encoding methicillin resistance, among CONS blood isolates from our unit.Methods. Clinical symptoms of septicemia, clinical outcome, and laboratory parameters of septicemia (Creactive protein) were studied retrospectively in 66 patients with CONS septicemia. The diagnosis of septicemia was made by the attending neonatologist and was defined by clinical symptoms of septicemia in the presence of a positive finding of a blood culture test, which was performed using a defined protocol. All CONS blood isolates were included to determine mec A gene carriage.Results. In the 66 patients, three treatment categories were distinguished: treatment with cephalothin (25 patients, 38%); with vancomycin (15 patients, 23%); and primary treatment with cephalothin, switched subsequently to vancomycin (26 patients, 39%). It was found that 92% of all CONS blood isolates (61/66) were mec A-positive. Concordance of mec A gene carriage with methicillin/oxacillin resistance was found in 56 of 66 isolates (85%); 10 of 61 (16%) isolates that were mec Apositive were determined as oxacillin-susceptible. Although 22 of the 25 blood isolates of the cephalothintreated patients were mec A-positive, clinical recovery was uneventful. In the 26 patients in whom antibiotic therapy was switched from cephalothin to vancomycin, two strains were cephalothin-susceptible and 8 patients already had recovered clinically before the switch, which was based solely on susceptibility test results.Conclusions. Cephalothin was found to be clinically efficacious in the treatment of neonatal CONS septicemia, despite a steadily increasing mec A gene carriage of CONS blood isolates in our neonatal intensive care unit and a corresponding high methicillin/oxacillin resistance. Hence, cephalothin remained the antibiotic of first choice in the treatment of CONS septicemia in our unit, with vancomycin selected exclusively for cases not responding to initial cephalothin treatment, or for patients developing CONS septicemia during or after recent cephalothin treatment. By applying this approach in our unit, we were able to reduce vancomycin use from 62% in 1994 to 1995 to 21% in 1997. This shows that such a policy may ...

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Clinical Outcome of Cephalothin Versus Vancomycin Therapy in the Treatment of Coagulase-negative Staphylococcal Septicemia in Neonates: Relation to Methicillin Resistance and mec A Gene Carriage of Blood Isolates

Krediet¹,

Jones

Gerards³

et al. 1999

Pediatrics

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“…However, 78 (81.25%) of 96 β-lactamase positive S. aureus strains were β-lactamase positive ORSA isolates, but none of them had vancomycin resistance. Some authors reported that clinical infections of both community and nosocomial origins caused by ORSA strains continue to be major therapeutic and infection control challenges (Sorrell et al 1982, Hackbarth & Chambers 1989. Recently, the vast majority of ORSA have been shown to produce β-lactamases (Massanari et al 1988, Montanari et al 1990, and vancomycin has been generally thought to be the agent of choice for invasive ORSA infections (Sorrell et al 1982).…”

Section: Discussionmentioning

confidence: 99%

Slime production and antibiotic susceptibility in staphylococci isolated from clinical samples

Arslan

Özkardeş

2007

Mem. Inst. Oswaldo Cruz

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Slime production is considered to be a significant virulence factor for some strains of staphylococci (Christensen et al. 1982, Davenport et al. 1986, Kleeman et al. 1993, Ammendolia et al. 1999, Mack et al. 2000. In coagulase-negative staphylococci (CNS), a loosely bound exopolysaccharides layer (slime) has been found in addition to capsule, and it has been associated with sepsis, including intravenous-catheter-related bacteremia and other prosthetic device infections (Ishak et al. 1985, Diaz-Mitoma et al. 1987, Etienne et al. 1988, Rupp & Archer 1994.Similarly, Staphylococcus aureus strains have bacterial capsules, which are closely associated with the bacterial cell wall. These strains may also have an extracapsular and labile extrapolysaccharidic structure (Caputy & Costerton 1982). Formerly slime production of S. aureus has never been considered as a virulence factor. Recently, some investigators reported that slimeproducing S. aureus strains had a higher colonization capacity than its non-slime-producing variants did. Therefore, S. aureus slime may play a role in the establishment of infection (Baselga et al. 1993, Ammendolia et al. 1999.The importance of the role played by slime is further increased by its frequent association to reduced antibiotic susceptibility (Kloos & Bannerman 1994). The difficulty in eradicating a chronic infection associated with slime formation has been reported, and slime-producing bacteria has been shown to resist higher antibiotic concentrations than non-slime-producing bacteria (Gristina et al. 1987). Moreover, detection of resistance to oxacillin in staphylococci is important to guide the therapy and prevent the patient from being unnecessarily treated with vancomycin, which is an antimicrobial agent that presents therapeutic complications, high costs, and may lead to the selection of resistant mutants (Marshall et al. 1999).In this study, we wanted to evaluate the occurrence of slime production among clinical isolates of both CNS and S. aureus by comparing different methods. To assess the relationship between slime and pathogenicity, we investigated the susceptibility to certain antimicrobial agents, particularly oxacillin. MATERIALS AND METHODSBacterial isolates -One hundred eighty seven staphylococcal isolates, provided by hospital laboratory, were obtained from culture of several specimens; 117 isolated from throat and nasal swabs, 32 from wounds, 21 from urine, 9 from blood, and 8 from catheters. Table I shows distribution of species and clinical samples in the 187 staphylococcal strains. These staphylococcal strains, specifically 115 S. aureus strains, 34 S. epidermidis strains, eight S. chromogenes strains, eight S. hominis strains, three S. saprophyticus strains, one S. lugdunensis strain, one S. capitis strain, one S. haemolyticus strain, one S. warneri strain, one S. cohnii subsp. cohnii strain, isolated from diverse clinical sources were studied. Isolates were characterized at the species level by the API Staph system (Biomerieux, France) according to the instruc...

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“…It appears to be bactericidal against staphylococci with in vitro activity that is comparable to that of glycopeptides such as vancomycin and teicoplanin (96,97). It has also been found to have activity against strains of MRSA with reduced susceptibility to vancomycin (97).…”

Section: Investigational Compoundsmentioning

confidence: 93%

The Management of Infection and Colonization due to Methicillin‐Resistant Staphylococcus aureus: A CIDS/CAMM Position Paper

Simor

Loeb²

2004

Canadian Journal of Infectious Diseases and Medical Microbiolog

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Methicillin-resistantStaphylococcus aureus(MRSA) is being seen with greater frequency in most hospitals and other health care facilities across Canada. The organism may cause life-threatening infections and has been associated with institutional outbreaks. Several studies have confirmed that MRSA infection is associated with increased morbidity and mortality compared with infections caused by susceptible strains, even when the presence of comorbidities is accounted for. Treatment of MRSA infection is complicated by the fact that these organisms are resistant to multiple antimicrobial agents, so treatment options are limited. The effectiveness of decolonization therapy (attempting to eradicate MRSA carriage) is also uncertain. This paper reviews the medical management of MRSA infections, discusses the potential role of decolonization and provides an overview of evidence to support recommended infection control practices.

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Methicillin-resistant staphylococci: detection methods and treatment of infections

Cited by 113 publications

References 93 publications

Clinical Outcome of Cephalothin Versus Vancomycin Therapy in the Treatment of Coagulase-negative Staphylococcal Septicemia in Neonates: Relation to Methicillin Resistance and mec A Gene Carriage of Blood Isolates

Clinical Outcome of Cephalothin Versus Vancomycin Therapy in the Treatment of Coagulase-negative Staphylococcal Septicemia in Neonates: Relation to Methicillin Resistance and mec A Gene Carriage of Blood Isolates

Slime production and antibiotic susceptibility in staphylococci isolated from clinical samples

The Management of Infection and Colonization due to Methicillin‐Resistant Staphylococcus aureus: A CIDS/CAMM Position Paper

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