Species distribution and clinical profiles of coagulase-negative staphylococci (CoNS) isolated from blood cultures among paediatric patients in Hospital Kuala Lumpur.

INTRODUCTION: Coagulase-negative staphylococci (CoNS) is often considered as a culture contaminants but it can potentially be pathogenic to patients with risk factors. A combination of species identification and clinical criteria has been suggested in determining true CoNS bacteraemia. OBJECTIVES: To identify the species distribution, antibiotic susceptibility patterns and clinical profiles of CoNS isolated from blood cultures among paediatric patients in Hospital Kuala Lumpur (HKL). METHODS: This study involved CoNS isolation from blood cultures of paediatric in-patients of the Paediatric Institute HKL. Isolates were identified to species level using Analytical Profile Index Staph identification strips and antimicrobial susceptibility pattern following Kirby-Bauer Disc Diffusion method. The clinical profiles of patients were obtained from their medical records. RESULTS: Eleven CoNS species were identified from 148 isolates. Staphylococcus epidermidis was the most frequent species isolated (67.6%). The majority of the isolates showed resistance to penicillin (85.8%); while 70.3% were methicillin-resistant (MR) CoNS, which demonstrated a significant association with true infection (p=0.021). Predictors for significant CoNS infection included thrombocytopaenia, presence of predisposing factors, nosocomial infection, blood collected from peripheral vein, and CoNS isolated from two consecutive blood cultures. The most common predisposing factors for the isolation of CoNS were the presence of peripheral (54.1%) and central venous catheters (35.1%). CONCLUSION: CoNS can cause significant bloodstream infections. The isolation of CoNS from blood cultures should be carefully interpreted by considering the predictive factors. Local data regarding predictive factors of patients with culture-positive CoNS, species distribution and antimicrobial susceptibility pattern are useful to determine the significance of blood culture results and care management of patients.

Conjunctival colonisation and antibiotic resistance of coagulase-negative Staphylococcus after cataract surgery: a 6-month longitudinal study at a medical centre in Taiwan.

OBJECTIVE: To explored 6-month longitudinal changes in conjunctival colonisation and antibiotic resistance profiles of coagulase-negative Staphylococcus (CNS) after cataract surgery with 1 month tobramycin treatment. DESIGN: Prospective cohort study between 1 August 2012, and 31 July 2013. SETTING: A single medical centre in Taiwan. PARTICIPANTS: A total of 128 Taiwanese patients with 46.9% of male participants. INTERVENTIONS: Samples from the conjunctival sacs of both operation (OP) and non-OP eyes were obtained separately before cataract surgery and at 1, 3 and 6 months after surgery. Tobramycin (0.3%) treatment was applied four times daily for 1 month postoperatively. MAIN OUTCOME MEASURE: Identification of CNS isolates and their antibiotic susceptibility by using disk diffusion or E-test. RESULTS: CNS was detected in 24.2% of patients at baseline. During postoperative follow-up, the CNS colonisation rate did not decrease in either eye but showed an increasing trend in the OP eyes at 1 month (p=0.06). The colonisation rate showed no significant difference between the OP and non-OP eyes from baseline to a specific follow-up. We observed a significant increase (p<0.05) in resistance to tobramycin at 1 month and to ciprofloxacin at 3 months in the OP eyes and to trimethoprim/sulfamethoxazole at 1 month and 3 months and to oxacillin at 6 months in the non-OP eyes. CONCLUSIONS: During the 6-month postoperative follow-up, 0.3% tobramycin administration failed to reduce CNS colonisation but increased resistance to several antibiotics. Postoperative antibiotic treatment may be replaced by other evidence-endorsed prophylactic routines.

Isolation, purification, and characterization of staphylocoagulase, a blood coagulating protein from Staphylococcus sp. MBBJP S43.

Staphylocoagulase, a protein produced by S. aureus, play major role in blood coagulation and investigations are in advance to discover more staphylocoagulase producing species. The present study demonstrates the identification of a coagulase producing bacteria and isolation, purification and characterization of the protein. The bacteria was identified using 16S rDNA sequencing and phylogenetic investigation, classified the bacteria as Staphylococcus sp. MBBJP S43 with Genbank accession number KX907247. Tube test and Chromozym TH assay were used to study enzyme activity and comparison was made with five standard coagulase positive strains. The SEM images of the fibrin threads provide evidence of coagulation. The optimum temperature for enzyme activity was 37°C and pH of 6.5-7.5. Glucose and lactose as a carbon source and ammonium chloride as nitrogen source greatly influenced the bacterial growth. Staphylocoagulase has been purified to homogeneity (766 fold) by 80% (NH4)2SO4 precipitation, Sephadex G-75 gel filtration, DEAE anion exchange chromatography, and HPLC using C18 column. SDS PAGE revealed the molecular weight of the protein to be approximately 66kD and FTIR spectra of the purified protein demonstrated the presence of α helical structure. Present study revealed that the Staphylococcus sp. MBBJP S43 strain is a potential staphylocoagulase producing bacteria.

Qualidade microbiológica de pescado comercializado em feiras livres de Palmas - TO / Microbiological quality of fish marketed in Palmas - TO

O pescado é um dos alimentos mais suscetíveis à deterioração. O objetivo desse trabalho foi avaliar a qualidade microbiológica e temperatura da Caranha (Piaractus mesopotamicus) em 27 amostras, Tambaqui (Colossoma macropomum) em 22 amostras e Tucunaré (Cichla sp.) em 2 amostras, comercializados em feiras livres pesando de 1 a 1,5 kg e analisar quanto à presença de Salmonella sp., Estafilococos coagulase positiva, Número Mais Provável de Coliformes totais e termotolerantes, Contagem total de bactérias Mesófilas e Contagem total de bactérias Psicrotróficas. Detectou-se Salmonella sp. em 11,1% das amostras de Caranha e 4,5% das amostras de Tambaqui; para coliformes a 45 °C, 14,8% das amostras de Caranha e 77,2% das amostras de Tambaqui apresentaram- se inadequadas, contudo todas as amostras estavam de acordo com a legislação para Estafilococos coagulase positiva. Foram encontradas bactérias Mesófilas e Psicrotróficas, sendo a temperatura inadequada em 22,2% das amostras de Caranha e 81,8% das amostras de Tambaqui, constatando assim, falhas no processo de armazenamento, manipulação e ausência de refrigeração.

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23

Abstract The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p < 0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence.

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23.

The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p<0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence.

The Impact of Implementation of Rapid QuickFISH Testing for Detection of Coagulase-Negative Staphylococci at a Community-Based Hospital.

OBJECTIVES: A study was conducted to evaluate the impact of implementing the Staphylococcus QuickFISH assay (AdvanDx, Woburn, MA), which rapidly detects and differentiates Staphylococcus aureus from coagulase-negative staphylococci (CoNS), together with an antimicrobial stewardship program on treating patients suspected of having sepsis. METHODS: Two patient groups showing CoNS in positive blood cultures were evaluated by either conventional or QuickFISH testing with respect to turnaround time (TAT) for microorganism identification following Gram stain. Length of hospital stay (LOS) and days on the antibiotic vancomycin (DOV) were also compared. RESULTS: QuickFISH identification test accuracy was 100% compared with conventional testing. Average values for TAT, LOS, and DOV were all decreased as the result of QuickFISH testing; for acute-care patients hospitalized for 10 days or less, the main population of interest for this study, these three measures were all reduced significantly following implementation of QuickFISH vs conventional testing (P < .001, P = .0484, and P = .0084, respectively). Based on certain assumptions, QuickFISH testing also led to substantial cost savings. CONCLUSIONS: The QuickFISH assay, with its ability to provide timely and actionable results nearly simultaneously with the Gram stain, in conjunction with an effective antimicrobial stewardship program, has been adopted as standard of care at our community-based hospital.

Japanese features of native valve endocarditis caused by coagulase-negative staphylococci: case reports and a literature review.

Although coagulase-negative staphylococci (CoNS) is a frequent cause of prosthetic valve endocarditis, native valve endocarditis (NVE) caused by CoNS is not commonly seen. Its high mortality is well known; however, there are no systematic reports published in Japan. We herein report the cases of two Japanese patients with CoNS NVE who were admitted to our hospital located in Tokyo and conduct literature searches on CoNS NVE in Japan from 1983 to March 2012 using PubMed and ICHUSHI WEB (Japan Medical Abstract Society). We also summarize the features of 22 Japanese patients with CoNS NVE, including our patients.

Influence of carvacrol and thymol on the physiological attributes, enterotoxin production and surface characteristics of Staphylococcus aureus strains isolated from foods

This study evaluated the influence of the phenolic compounds carvacrol (CAR) and thymol (THY) on some physiological characteristics and on the modulation of the secretion of some staphylococcal virulence factors, that is, coagulase and enterotoxin. This study also investigated possible mechanisms for the establishment of the anti-staphylococcal activity of these compounds. Sublethal concentrations (0.3 and 0.15 µL/mL) of CAR and THY inhibited the activity of the enzymes coagulase and lipase and led to a decrease in salt tolerance. At the tested sublethal concentrations, both CAR and THY led to a total suppression of enterotoxin production. The loss of a 260-nm-absorbing material and an efflux of potassium ions occurred immediately after the addition of CAR and THY at 0.6 and 1.2 µL/mL and increased up to 120 min of exposure. Electron microscopy of cells exposed to CAR and THY (0.6 µL/mL) revealed that individual cells appeared to be deformed, with projections of cellular material. The observations of leakage of cellular material and an altered cell surface suggest that gross damage to a cell's cytoplasmic membrane, which results in a disruption in protein secretion, could be responsible for the anti-staphylococcal properties of CAR and THY.

Prevalence, aetiology and antibiotic resistance profiles of coagulase negative staphylococci isolated in a teaching hospital

In this paper we carried out a study about prevalence of the clinically significant coagulase negative staphylococcal (CNS) isolates found in an university hospital. Two hundred four CNS isolates from 191 patients obtained between the period of 1998 to 2002, were studied. About 27 percent (52/191) of the infection cases studied were confirmed as CNS-associated diseases. Blood stream infection (BSI) was the most frequent CNS associated-disease (25 percent; 13/52). The great majority of the BSI was verified in the Neonatal Intensive Care Unit (NICU). The analysis of the 52 patients medical history showed that 85 percent of the BSI was acquired in hospital. Most of the CNS nosocomial infections were associated with the use of indwelling medical devices. The incidence of methicillin-resistance among significant CNS isolates was 38 percent. In this study, a high percentage of exogenous contaminant was verified (60 percent), indicating that contamination of clinical specimens during sample collection is critical.

Detection of enterotoxin genes of Staphylococcus sp isolated from nasal cavities and hands of food handlers

Food handlers, an important factor in food quality, may contain bacteria that are able to cause foodborne disease. The present study aimed to research coagulase-negative (CNS) and -positive staphylococci (CPS) in 82 food handlers, analyzing nasal and hand swabs, with identification of 62 CNS (75.6 percent) and 20 CPS strains (24.4 percent). Staphylococcal enterotoxins genes were investigated by PCR. In 20 CPS strains, 19 were positive for one or more genes. The percentage of CNS presenting genes for enterotoxins was high (46.8 percent). Despite of the staphylococcal species, the most common gene was sea (35.4 percent), followed by seh and sej (29.2 percent). The detection of new staphylococcal enterotoxins (SEs) genes showed a higher pathogenic potential in this genus. The presence of these gene points out the importance of CNS not only as contaminant bacteria but also as a pathogen.

Rapid and simple method for serotyping of staphylocoagulase using polystyrene latex particles.

The serotyping of staphylocoagulase is widely used in Japan. However, the conventional immunoassay based on neutralization of the antisera is so laborious and time-consuming that it is not widely used in the other countries. In order to overcome these drawbacks we developed a novel staphylocoagulase serotyping method based on a microplate format using polystyrene latex particles. Addition of latex particles promotes the formation of fibrin complexes, which represents a more rapidly and easily detected endpoint. For 83 strains, 90% were classified into serotypes within 3 h, and there was no discrepancy in the results between our method and the conventional method. These results indicate that the present microplate method is rapid, simple, and interpretable.

Perfil celular e microbiológico do leite de ovelhas Santa Inês no período lactante e pós-desmame / Cellular and microbiological profile of Santa Ines ewes in the lactation and the post-weaning period

The aim was to evaluate and compare the microbiological and cellular profile of the milk of Santa Ines ewes during the lactation period and the active involution. Milk samples were analyzed from 12 ewes during these distinct periods. Clinical examination of the mammary gland, somatic cell count (SCC), California Mastitis Test (CMT), bacteriologic screening and sensibility of the pathogens in vitro were performed. Most alterations were observed in the active involution period. SCC and CMT were higher in this same period. Besides this, a high persistency of infection occurred. The active involution period did not show high susceptibility. Coagulase-negative staphylococci were the only isolated bacteria. A high antimicrobial sensibility of these pathogens was also encountered.

O objetivo deste trabalho foi avaliar o perfil microbiológico e celular do leite no período lactante e de involução ativa de ovelhas da raça Santa Inês. Foram avaliadas amostras lácteas de 12 ovelhas durante estes distintos períodos. Realizou-se o exame físico da mama, sendo as amostras lácteas submetidas à contagem de células somáticas (CCS), ao California Mastitis Test (CMT), ao exame microbiológico e aos testes de sensibilidade in vitro dos patógenos encontrados. Foram observados maiores escores do exame físico, CCS, CMT durante o período de involução ativa, além de uma alta persistência da infecção durante estes períodos. O período de involução ativa não se mostrou como um momento de alta susceptilidade. Os estafilococos coagulase negativa representaram o único gênero isolado das glândulas infectadas. Uma alta sensibilidade dos agentes etiológicos envolvidos frente aos diferentes antimicrobianos in vitro foi também observada.

Coagulase-negative staphylococci isolated from bovine extramammary sites and intramammary infections in a single dairy herd.

Isolates of various species of coagulase-negative staphylococci (CNS) from extramammary swab samples were compared with isolates of bovine mastitis CNS species. Swab samples were taken from perineum skin and udder skin, teat apices and teat canals of lactating dairy cows of the research dairy herd of the University of Helsinki in 1999 and 2002. In addition, hands of herd staff and liners of teat cups were sampled for CNS. CNS isolates from milk samples of subclinical or clinical mastitis in the same herd were collected during 1998-2002. Species identification was performed using phenotyping (API Staph ID 32 test) and by constructing a 16 and 23S rRNA RFLP library (ribotyping). Based on phenotype, 84% of mastitis isolates and 57% of extramammary isolates were identified at species level with >90% probability. Ribotype patterns formed 24 clusters, and 15 of them included a CNS type strain. If the ribotype clusters contained isolates of both extramammary and mastitis origin, they were further typed using pulsed-field gel electrophoresis (PFGE). The predominant CNS species in mastitis, based both on phenotyping and genotyping, were Staph. chromogenes and Staph. simulans. Phenotyping failed to identify half of the extramammary isolates. Based on phenotyping, Staph. equorum and Staph. sciuri, and based on ribotyping, Staph. succinus and Staph. xylosus, were the predominant CNS species in extramammary samples. The most common species in milk samples, Staph. chromogenes, was also isolated from several extramammary samples, and five out of ten pulsotypes were shared between mastitis and extramammary isolates, indicating that strains from udder skin are highly similar. The second commonest mastitis species, Staph. simulans, was isolated only from three extramammary samples, indicating that Staph. simulans may be more specifically associated with mastitis. Consequently, the origin of CNS mastitis may vary depending on the causing CNS species.

Detecção da produção de slime por estafilococos coagulase-negativa isolados de cateter venoso central / Detection of slime production by coagulase-negative staphylococci isolated from central venous catheter

A produção de slime é um importante fator de virulência dos estafilococos coagulase-negativa, permitindo-lhes aderir sobre as superfícies lisas de biomateriais, e por isso, é associada aos processos de infecção de implantes. No presente estudo a produção de slime em 27 cepas de estafilococos coagulase-negativa foi investigada por cultura em ágar vermelho Congo (77,7% de positividade), método espectrofotométrico ou damicroplaca (81,4% de positividade) e microscopia eletrônica de varredura (88,9% de positividade). Foi também avaliada a resistência de estafilococos coagula-se negativa a vários antimicrobianos usando a técnica do disco difusão. A porcentagem de resistência à penicilina G, oxacilina, eritromicina, clindamicina e gentamicinaem estafilococos produtores de slime foi respectivamente de 88,9%; 70,4%; 81,5%; 66,7% e 59,2%; todos os estafilococos coagulase-negativa foram vancomicina sensíveis. As cepas isoladas de cateter venoso central foram identificadas por método convencional e sistema API Staph. Os 27 estafilococos coagulase-negativa foram identificados como: S. saprophyticus (3,7%), S. xylosus(7,4%), S. haemolyticus (14,8%), S. epidermidis (37,0%), S. warneri (14,8%), S. lugdunensis (7,4%), S. hominis (7,4%), S. schleiferi (3,7%) e S. chromogenes (3,7%). Pode-se concluir que entre a maioria das espécies Staphylococcus coagulase-negativa houve associação entre a produção de slime, origem nosocomial das cepase reduzida sensibilidade aos antimicrobianos, sugerindo potencial patogênico no ambiente hospitalar.

Slime production is an important virulence factor of coagulase-negative Staphylococcus spp., allowing them to attach to smooth surfaces of biomaterials, and it has been associated with infections of implanted medical devices. In the present study the production of slime capsules in 27 strains of coagulase-negative Staphylococcus was investigated by culture in Congo Red agar (77.7% positivity), spectrophotometric or microplate method (81.4% positivity) and scanning electron microscopy (88.9% positivity). The resistance of coagulase-negative strains of Staphylococcus to various antimicrobial agents was also determined by agar disk diffusion. The proportion of strains resistant to penicillin G, oxacillin, erythromycin, clindamycin and gentamicin among the slime-producing staphylococci was 88.9%, 70.4%, 81.5%, 66.7% and 59.2%, respectively; all of the coagulase-negative staphylococci were susceptible to vancomycin. The strains isolated from central venous catheters were identified by a conventional method and the API Staph system. The 27 coagulase-negative taphylococcus strains were identified as: S. saprophyticus (3.7%), S. xylosus (7.4%), S. haemolyticus (14.8%), S. epidermidis (37.0%), S. warneri (14.8%), S. lugdunensis (7.4%), S. hominis (7.4%), S. schleiferi (3.7%) and S. chromogenes (3.7%). It can be concluded that in the most of the coagulase-negative Staphylococcus species there was an association between slime production, the nosocomial origin of the strains and reduced sensitivity to the antibiotics, suggesting a pathogenic potential in the hospital environment.

Tipificación de estafilococos coagulasa negativa resistentes a la novobicina aislados de muestras clínicas / Standardisation of isolated resistant estafilococos coagulasa negative to the novobicina of clinical samples

Estudio realizado a 44 cepas para conocer la especie estafilococos coagulasa negativa (ECN) resistentes a la novobiocina

Investigation of mediastinitis due to coagulase-negative staphylococci after cardiothoracic surgery.

Six cases of coagulase-negative staphylococcal mediastinitis were identified in the latter half of 1999. A new preoperative cleansing solution was suspected by hospital staff to be a factor in the outbreak. We evaluated this possible risk factor along with other known and suspected surgical site infection risk factors in this case-control study.

The role of Staphylococcus aureus adhesins in the pathogenesis of ventricular assist device-related infections.

Ventricular assist devices (VADs) are an important form of therapy for end-stage congestive heart failure. However, infection of the VAD, which is often caused by Staphylococcus aureus, poses a major threat to survival. Using a novel in vitro binding assay with VAD membranes and a heterologous lactococcal system of expression, we identify 3 S. aureus proteins--clumping factor A (ClfA) and fibronectin binding proteins A and B (FnBPA and FnBPB) as the main factors involved in adherence to VAD polyurethane membranes. Adherence is greatly diminished by long implantation times, reflecting a change in topological features of the VAD membrane, and is primarily mediated by the FnBPA domains in the staphylococcal proteins. We also compare the adherence of S. aureus mutant strains and show that other staphylococcal components appear to be involved in adherence to VAD membranes. Finally, we demonstrate that ClfA, FnBPA, and FnBPB mediate bacterial infection of implanted murine intra-aortic polyurethane patches.

A clone of coagulase-negative staphylococci among patients with post-cardiac surgery infections.

Coagulase-negative staphylococci (CoNS) are important causes of hospital-acquired infections such as infections after cardiac surgery. Efforts to reduce these infections are hampered by the lack of knowledge concerning the epidemiology of CoNS in this setting. Forty strains of CoNS collected during the surgical revision of 27 patients operated on between 1997 and 2000 were analysed. Strains were also collected from the ambient air in the operating suite. Their pulsed-field gel electrophoresis (PFGE) characteristics and antibiotic resistance were analysed. Using PFGE 19 of 40 strains from 15 of 27 patients were shown to belong to one clone, and strains from this clone were also isolated from the ambient air. This clone had caused infections throughout the period. Antibiotic resistance did not correlate with PFGE patterns. Using PFGE one clone could be identified that caused 56% of the CoNS infections during this period. A strain from this clone was also found in the air of the operating suite suggesting the origin of the CoNS causing infections was the hospital environment.

Prediction of mecA-positive coagulase-negative staphylococci: assessment of different phenotypic methods, breakpoints, culture media and culture conditions.

Sensitivity for the detection of mecA-positive coagulase-negative staphylococci (CNS) was evaluated for different breakpoints of resistance for oxacillin using three different susceptibility tests, either on Mueller-Hinton agar supplemented with 2% NaCl (MH-NaCl agar) or on paper disc method agar supplemented with 5% defibrinated blood (PDM-blood agar). The Etest, multipoint inoculation test and disc diffusion test showed comparable sensitivity (0.96, 0.96 and 0.95, respectively) using an oxacillin breakpoint of > or = 0.5 mg/L or < or = 17 mm for the disc test, after incubation at 35 degrees C for 24 h on MH-NaCl agar. The sensitivity decreased for breakpoints > or = 1 mg/L and when PDM-blood agar was used instead of MH-NaCl agar.