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No. of bitstreams: 2 Dissertação - Jéssica de Oliveira Veloso - 2016.pdf: 2794813 bytes, checksum: 8bd9adfbbc795e1b905411f5c2a04d01 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-09-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Staphylococcus aureus is an important pathogen related to nosocomial infections, with high prevalence, morbidity and mortality rates. In this context, the Intensive Care Units (ICU) has been high-risk areas for the selection of multiresistant strains. The environment (objects, equipment and surfaces) of an ICU can also get contaminated, and microorganisms may remain viable for a long period of time, and can colonize patients, employees, visitors and other environments. The objectives of the study were to determine the prevalence of S. aureus contamination in patients and ICU environment of a university hospital in the city of Goiânia-GO, as well as to determine the antimicrobial susceptibility and virulence profile of the isolates and perform molecular typing of methicillin-resistant S. aureus (MRSA) isolates. The isolation and presumptive identification of S. aureus by phenotypic techniques and the confirmation of the species by detection of femA gene by PCR were performed. The isolates were subjected to diskdiffusion test for determining antimicrobial susceptibility profile, and those showing resistance to cefoxitin were subjected to E-Test® to determine the minimum inhibitory concentration (MIC) to oxacillin and vancomycin, as well as the mecA gene detection for identification of MRSA strains. In these isolates the SCCmec typing was performed. In all S. aureus isolates were detected virulence factors-coding genes and held the genetic comparison for determining the similarity profile by pulsed field gel electrophoresis. Fifty hundred and thirty six swabs were collected being 134 of patients and 402 of ICU environment. The prevalence of colonization by S. aureus was 12.7% (68/536), being 13.4% (18/134) for patients and 12.4% (50/402) for the environment. The highest resistance rate presented was to penicillin (85.3%) followed by erythromycin (69.1%) clindamycin (66.2%) and sulfamethoxazole-trimethoprim (54.4%). Fifty-six isolates (82.4%) were classified as multiresistant. The prevalence of MRSA was 20.6% (14/68), and seven isolates (10.3%) presented intermediate susceptibility to vancomycin (VISA). The inducible resistance phenotype (iMLSb) was found in 11 strains (16.2%) and the constitutive resistance (cMLSb) in 25 (36.8%). Eleven isolates showed genes encoding for at least one virulence factor and were detected six virulence profiles. Of the 14 MRSA strains, six (42.9%) were SCCmec type IV, five (35.7%) SCCmec type I, two (14.3%) SCCmec type II and one (7.1%) SCCmec type III. PFGE analysis showed genetic diversity among the isolates, although a cluster grouped 16 isolates showing the spread of the bacteria among patients and environment. One MRSA isolate showed genetic relationship to the USA300 strain and two isolates MRSA/VISA were similar and another identical to the clone USA400. The results suggest that the prevalence of S. aureus and MRSA remains high in health institutions, especially in the ICU, with high rates of antimicrobial resistance and pathogenic potential. The detection of these microorganisms in the environment shows risk of cross-transmission primarily via health professionals. Identification of isolates with genetic background of strains acquired in the community alert to a flow of intra and inter- hospital and community environment. In addition, it is believed that environmental surfaces can be acting as reservoirs of genes of resistance and virulence as well as potential sources of contamination to patients, professionals and environments. / Staphylococcus aureus é um importante patógeno relacionado a infecções nosocomiais, com elevadas taxas de prevalência, morbidade e mortalidade. Nesse contexto, as Unidades de Terapia Intensiva (UTI) tem sido áreas de alto risco para a seleção de cepas multirresistentes. O ambiente (objetos, equipamentos e superfícies) de uma UTI também pode se contaminar, e os microrganismos podem permanecer viáveis por um longo período de tempo, podendo colonizar pacientes, trabalhadores, visitantes e contaminar ainda outros ambientes. Os objetivos do estudo foram determinar a prevalência de colonização por S. aureus em pacientes e ambiente da UTI de um hospital universitário na cidade de Goiânia-GO, bem como o perfil de susceptibilidade antimicrobiana e perfil de virulência dos isolados e realizar a tipagem molecular dos S. aureus resistentes à meticilina (MRSA). Foi realizado o isolamento e identificação presuntiva de S. aureus por técnicas fenotípicas e a confirmação da espécie pela detecção do gene femA por PCR. Os isolados foram submetidos ao teste de disco-difusão para determinação do perfil de suscetibilidade antimicrobiana e aqueles que apresentaram resistência à cefoxitina foram submetidos ao E-test® para determinação da concentração inibitória mínima à oxacilina e vancomicina, assim como, à detecção do gene mecA para identificação das cepas MRSA. Nestes isolados foi realizada a tipagem do SCCmec. Em todos os S. aureus isolados foi realizada a detecção dos genes codificadores de fatores de virulência e a comparação genética para determinação do perfil de similaridade por eletroforese em gel em campo pulsado. Foram coletados 536 swabs sendo 134 de pacientes e 402 de ambiente de UTI. A prevalência de colonização por S. aureus foi de 12,7% (68/536), sendo 13,4% (18/134) para pacientes e 12,4% (50/402) para o ambiente. A maior taxa de resistência apresentada foi à penicilina (85,3%) seguida da eritromicina (69,1%), clindamicina (66,2%) e sulfametoxazol-trimetoprim (54,4%). Cinquenta e seis isolados (82,4%) foram considerados multirresistentes. A prevalência de MRSA foi de 20,6% (14/68), houve ainda a existência de sete (10,3%) isolados com suscetibilidade intermediária à vancomicina (VISA). O fenótipo de resistência induzível (iMLSb) foi encontrado em 11 isolados (16,2%) e o de resistência constitutiva (cMLSb) em 25 (36,8%). Onze isolados apresentaram genes codificadores para pelo menos um fator de virulência pesquisado, sendo detectados seis perfis de virulência. Das 14 cepas MRSA, seis (42,9%) foram SCCmec tipo IV, cinco (35,7%) SCCmec tipo I, duas (14,3%) SCCmec tipo II e uma (7,1%) SCCmec tipo III.A análise de PFGE revelou diversidade genética entre os isolados, apesar de que um cluster agrupou 16 isolados mostrando a disseminação da bactéria entre pacientes e fômites. Um isolado MRSA mostrou relacionamento genético à cepa USA300 e dois isolados MRSA/VISA foram semelhantes e outro idêntico ao clone USA400. Os resultados sugerem que a prevalência de S. aureus e MRSA permanece elevada em instituições de saúde, especialmente em UTI, com elevadas taxas de resistência antimicrobiana e potencial patogênico. A detecção desses microrganismos no ambiente evidencia risco de transmissão cruzada desses patógenos, principalmente via profissionais da saúde. A identificação de isolados com background genético de cepas adquiridas na comunidade alerta para um fluxo de disseminação intra e inter-ambiente hospitalar e comunitário. Além disso, acredita-se que as superfícies ambientais podem estar atuando como reservatórios de genes de resistência e virulência, bem como fontes potenciais de contaminação de pacientes, profissionais e ambientes.

Staphylococcus aureus (S. aureus) is a ubiquitous bacterium that has the potential to cause severe disease in children and adults. Asymptomatic carriage of S. aureus is an important risk factor for developing infection, as well as a key contributor to transmission. Despite the fact that child care workers are at risk of infections, little research has focused on asymptomatic carriage of S. aureus in this occupational group. We collected samples from 110 employees, 81 children, and 214 surfaces at twelve child care facilities, as well as 111 age- and gender-matched adults not employed at child care centers. After adjusting for age, a household contact with a recent influenza-like illness, and a household contact with exposure to cattle, the odds ratio for S. aureus carriage in child care employees was 0.68 (95% CI 0.31 - 1.50, p-value 0.34). The odds of MRSA carriage was 3.09 times higher in child care employees than unexposed adults after adjusting for a history of cigarette smoking (95% CI 1.04 - 9.17, p-value 0.042). Colonization rates of all S. aureus and MRSA in children were 19.8% and 1.23%, respectively. S. aureus and MRSA were isolated from 9.80% and 0.90% of surfaces. Washing children's hands upon arrival had a protective effect among employees (adjusted OR 0.17, 95% CI 0.095 - 0.32, p < 0.0001). Molecular characterization suggested transmission of S. aureus among children, employees, and environmental surfaces. While the overall prevalence of MRSA is low at child care facilities, employees may be at increased risk of carrying this organism.

Methicillin-Resistant Staphylococcus aureus (MRSA) began as a nosocomial infection due to overuse of antibiotics. Several previous studies have reported an increase in this infection in adult patients who have not been hospitalized. It has also been reported that there is an increase in MRSA in children. Some of these children became infected even though they were not at high risk for the infection. After approval from the All Children's Hospital Institutional Review Board (IRB), a cross sectional study was conducted with pediatric admissions and pediatric emergency room visits to determine the characteristics of Methicillin-Sensitive Staphylococcus aureus and MRSA. During this study, a review of 672 medical charts was conducted. The study participants ranged in age from newborns to 18 years of age. In order to be enrolled in the study, the subjects' cultures were collected either as outpatients or within 72 hours of admission. The data that was collected from each chart included age, race/ethnicity, gender, type of infection, preexisting medical conditions, and risk factors for infection. The potential risk factors include antibiotic use, previous surgery or outpatient procedure, previous MRSA infection, immunotherapy, community worn device, and residence in a facility. Statistical analysis was conducted using Epi Info and SAS software packages. In regards to demographic characteristics, black children are 2.98 times more likely to have an MRSA infection than white children. Gender and age were not risk factors for the development of the infection. The risk factors that were significant in whites were home health care (OR= 6.12, CI= 5.16, 7.08), community worn device (OR= 2.28, CI= 1.67, 2.89), previous hospitalization (OR= 2.43, CI= 1.95, 2.91), previous MRSA infection (OR= 3.69, CI= 2.90, 4.48), and previous surgery (OR= 2.02, CI= 1.51, 2.53). In blacks, females were more likely to have MRSA (OR= 2.57, CI= 1.73, 3.41). This finding may be due to the small sample size of black children in the study. Of the analyzed risk factors, home health care (OR= 2.95, CI= 1.11, 4.79), community worn device (OR= 2.85, CI= 1.71, 4.01), previous hospitalization (OR= 1.98, CI= 1.13, 2.83), previous surgery (OR= 2.79, CI= 1.79, 3.79), and previous antibiotic (OR= 5.60, CI= 4.66, 6.54) use were all significant risk factors in blacks. Effect modification was tested between race and all risk factors. Race was an effect modifier only for the risk factor of previous antibiotic use (pvalue =.02). Adjustment of confounding was performed for each race due to the presence of effect modification. After the adjustment for confounding in whites, only home health care (OR=4.37 CI= 1.55, 12.32), previous MRSA infection (OR= 2.86 CI= 1.16, 7.05), and previous hospitalization (OR= 2.00 CI= 1.14, 3.50) remained statistically significant. In blacks, after adjustment of confounding, only previous antibiotic use (OR= 5.13 CI= 1.75, 15.08) remained significant. Adjustment for confounding was also preformed on the total risk factors model. A dose response relationship was present with increasing risk factors present.

Beobachtung nosokomialer Infektionen bei intensivhospitalisierten Patienten im Rahmen einer einjährigen prospektiven, multizentrischen Kohortenstudie. Besondere Beachtung von Komplikationen wie Sepsis und Peritonitis sowie des Auftretens multiresistenter Keime bei der Infektentstehung. / Surveillance of nosocomial ICU-acquired infections in intensive care unit patients in a 1-year prospective multicenter cohort study. Monitoring of complications like sepsis and peritonitis and acquisition of multi-resistant infectious agents.

<p>The purpose of this study was to describe the level of knowledge that nurse students in term 6 have about Methicillin-Resistant Staphylococcus aureus (MRSA) and basic hygiene routines. The data collection was carried out by questionnaires. The questionnaire contained questions about knowledge regarding MRSA and basic hygiene routines. The questionnaires were handed out at an obligatory tuition occasion and all of the nurse students who were present (n=57) were asked to take part. The sample consisted of 45 women and 12 men. The youngest participant was 22 years old and the oldest participant was 52 years old. The main results showed a large variation regarding the participants knowledge on the subjects. Regarding questions about basic hygiene routines the majority had given the right answers. The number of right answers in the survey on questions about the participants knowledge of MRSA was lower. Only 12 % had given the right answer to the question about common symptoms of MRSA infection. Regarding the question about whether the nurse students considered themselves knowledgeable enough about MRSA for their future occupation, 32% had answered "to a high degree".</p> / <p>Syftet med studien var att beskriva vilka kunskaper sjuksköterskestuderande i termin 6 har om Methicillinresistenta Staphylococcus aureus (MRSA) och basala hygienrutiner. Datainsamlingen genomfördes med enkäter. Enkäten innehöll frågor om kunskaper gällande MRSA samt basala hygienrutiner. Enkäterna delades ut vid ett obligatoriskt undervisningstillfälle och samtliga, vid undervisningstillfället närvarade sjuksköterskestudenter (n =57) tillfrågades om deltagande. Undersökningsgruppen bestod av 45 kvinnor och 12 män. Yngsta deltagaren var 22 år och den äldsta deltagaren var 52 år. Huvudresultatet visade en stor variation gällande deltagarnas kunskaper i ämnena. På frågor angående basala hygienrutiner hade majoriteten svarat rätt. På de frågor som berörde deltagarnas kunskaper om MRSA var antalet rätta svar i undersökningen lägre. Endast 12 % hade svarat rätt på frågan om symtom som är vanliga vid MRSA infektion. På frågan om sjuksköterskestudenterna ansåg att de hade tillräckliga kunskaper om MRSA för sitt kommande yrke som sjuksköterskor svarade 32 % ”i hög grad”.</p>

The purpose of this study was to describe the level of knowledge that nurse students in term 6 have about Methicillin-Resistant Staphylococcus aureus (MRSA) and basic hygiene routines. The data collection was carried out by questionnaires. The questionnaire contained questions about knowledge regarding MRSA and basic hygiene routines. The questionnaires were handed out at an obligatory tuition occasion and all of the nurse students who were present (n=57) were asked to take part. The sample consisted of 45 women and 12 men. The youngest participant was 22 years old and the oldest participant was 52 years old. The main results showed a large variation regarding the participants knowledge on the subjects. Regarding questions about basic hygiene routines the majority had given the right answers. The number of right answers in the survey on questions about the participants knowledge of MRSA was lower. Only 12 % had given the right answer to the question about common symptoms of MRSA infection. Regarding the question about whether the nurse students considered themselves knowledgeable enough about MRSA for their future occupation, 32% had answered "to a high degree". / Syftet med studien var att beskriva vilka kunskaper sjuksköterskestuderande i termin 6 har om Methicillinresistenta Staphylococcus aureus (MRSA) och basala hygienrutiner. Datainsamlingen genomfördes med enkäter. Enkäten innehöll frågor om kunskaper gällande MRSA samt basala hygienrutiner. Enkäterna delades ut vid ett obligatoriskt undervisningstillfälle och samtliga, vid undervisningstillfället närvarade sjuksköterskestudenter (n =57) tillfrågades om deltagande. Undersökningsgruppen bestod av 45 kvinnor och 12 män. Yngsta deltagaren var 22 år och den äldsta deltagaren var 52 år. Huvudresultatet visade en stor variation gällande deltagarnas kunskaper i ämnena. På frågor angående basala hygienrutiner hade majoriteten svarat rätt. På de frågor som berörde deltagarnas kunskaper om MRSA var antalet rätta svar i undersökningen lägre. Endast 12 % hade svarat rätt på frågan om symtom som är vanliga vid MRSA infektion. På frågan om sjuksköterskestudenterna ansåg att de hade tillräckliga kunskaper om MRSA för sitt kommande yrke som sjuksköterskor svarade 32 % ”i hög grad”.

Coagulase positive staphylococci, Staphylococcus aureus and Staphylococcus pseudintermedius, are important causes of infection in human beings and dogs respectively. The rapid increase in the incidence of methicillin resistant S. aureus (MRSA) in people and its emergence in dogs has raised the profile of this organism in the veterinary community. Similarly, human S. pseudintermedius infections have also been recognized as the awareness of bidirectional human-dog transmission increases. Antimicrobial resistance has been complicating the treatment of S. aureus infections since the first penicillin resistance was observed in the 1940s. Methicillin resistance (resistance to the majority of â-lactams), is particularly troublesome as the â-lactams are a safe and effective class of antimicrobials for treating susceptible staphylococcal infections in both human beings and dogs. Additionally, resistance to other antimicrobial classes such as the macrolides, tetracyclines, sulfonamides and chloramphenicol, further complicates the treatment of staphylococcal infections. Particularly in small animal private practice, infections are often treated empirically, requiring knowledge of locally prevalent susceptibility patterns. The emergence of resistance to commonly used drugs necessitates surveillance to monitor the dissemination of resistance, and to guide antimicrobial therapy. In the last decade there have been many studies attempting to address gaps in our knowledge of the ecology of S. aureus and S. pseudintermedius in dogs. In particular, the prevalence of colonization with methicillin resistant staphylococci has been documented in different dog populations. However, failing to sample all relevant sites of colonization, may have decreased the sensitivity of these studies. The sites where coagulase positive staphylococci colonize dogs have not been systematically evaluated. The clinical and infection control implications of S. aureus infections, or colonization in the case of MRSA, requires timely laboratory identification. The tube coagulase test is arguably the most important tool used for identifying of staphylococcal species. Studies dating from the 1970s and 1980s suggested that the use of rabbit plasma, which is the current standard, may not be the ideal media for all situations and that different plasmas may need to be considered in different diagnostic situations. In this thesis, the ecology of coagulase positive staphylococci in dogs was studied from start to finish including sample collection, bacterial identification, antimicrobial susceptibility testing and molecular epidemiological investigations. This thesis will serve as a template to be used for follow up studies or by investigators setting up a surveillance program in their region. We found that multiple sites of colonization (nares, pharynx and rectum), are involved in both S. aureus and S. pseudintermedius carriage in dogs. Single site colonized dogs were identified, suggesting that maximal screening sensitivity requires sampling multiple body sites. When canine and rabbit plasma were compared, the time until clot formation was found to be significantly shorter with canine plasma. Although, the availability of canine plasma may limit its use in the diagnostic laboratory, investigators should be aware that rabbit plasma may not be ideal for all applications of the tube coagulase test. Antimicrobial susceptibility testing of canine S. aureus and S. pseudintermedius and human S. aureus isolates was done. Consistent with previous reports from Saskatoon, the S. pseudintermedius isolates were found to be overwhelmingly susceptible: pan-susceptibility was the most common phenotype identified. Antimicrobial resistance was more common among S. aureus than S. pseudintermedius including resistance to drugs which all S. pseudintermedius were susceptible to. No resistance to vancomycin, linezolid, daptomycin or quinupristin/dalfopristin was found. All isolates remained susceptible to at least one of tetracycline, clindamycin, chloramphenicol or trimethoprim/sulfamethoxazole which are often used for treating infections caused by multidrug resistant staphylococci. Finally, DNA fingerprinting revealed that the canine and human S. aureus isolates tested did not belong to mutually exclusive populations. Using AFLP, IS-typing and spa typing, many human and canine isolates were indistinguishable suggesting a common population, supporting the hypothesis that interspecies transmission occurs. The complex and under-characterized ecology of S. aureus and S. pseudintermedius requires more study so that risk factors for infection can be defined and effective infection control measures implemented. Because multiple species are involved, collaboration between veterinarians and human health professionals is imperative, and will no doubt yield the most success in our efforts to understand these potential pathogens.

Methicillin Resistant Staphylococcus aureus (MRSA) is one of the most important threats of nosocomial infections in many regions of the world and Vancomycin Resistant Enterococcus (VRE) is an emerging pathogen that develops full resistance against third-generation glycopeptide antibiotics. Conventional methods for identification of MRSA and VRE generally depend on culturing, which requires incubation of biological samples at least 24-72 hours to get accurate results. These methods are time consuming and necessitate optical devices and experts for evaluation of the results. On the other hand, early diagnosis and initiation of appropriate treatment are necessary to decrease morbidity and mortality rates. Thus, new diagnostic systems are essential for rapid and accurate detection of biological analytes at the point of care. This study presents design, fabrication, and implementation of MEMS based micro electrochemical sensor (&micro / ECS) to detect the methicillin resistance in Staphylococcus aureus and vancomycin resistance in Enterococcus species. To the best of our knowledge, the developed sensor is the first &micro / ECS which utilizes on-chip reference (Ag), working (Au), and counter (Pt) electrodes together with a microchannel to detect MRSA and VRE. The characterization of the designed sensor was achieved analyzing the interactions of the buffer solutions and solvents with the electrodes and Parylene C film layer by using optical and electrochemical methods. Specific parts of genes that are indicators of antimicrobial resistances were used in order to detect the resistances with high selectivity and sensitivity. Thus, synthetic DNA and bacterial PCR product were used as target probes in redox marker based detection and enzyme based detection, respectively. In order to enhance the hybridization, folding structures of the capture probe were investigated by using mfold Web Server. In redox marker based detection, the hybridization of DNA was indirectly detected by using Hoechst 33258 as redox marker with differential pulse voltammetry. The cross reactivity of the tests were performed by using different target probes of femA genes of S. aureus and S. epidermis, which are the major genes detected in methicillin detection assays. Consequently, amplification of signal by using horseradish peroxidase and TMB/H2O2 as substrate was achieved in order to enhance detection sensitivity. The sensor could detect 0.01 nM 23-mer specific part of mecA gene with redox marker based detection and 10 times diluted PCR product with enzyme-based detection in about six hours including the steps of sample preparation from whole blood. This sensor with its compatibility to MEMS fabrication processes and IC technology has a promising potential for a hand-held device for POC through the integration of micropotentiostat.

Coagulase positive staphylococci, Staphylococcus aureus and Staphylococcus pseudintermedius, are important causes of infection in human beings and dogs respectively. The rapid increase in the incidence of methicillin resistant S. aureus (MRSA) in people and its emergence in dogs has raised the profile of this organism in the veterinary community. Similarly, human S. pseudintermedius infections have also been recognized as the awareness of bidirectional human-dog transmission increases. Antimicrobial resistance has been complicating the treatment of S. aureus infections since the first penicillin resistance was observed in the 1940s. Methicillin resistance (resistance to the majority of â-lactams), is particularly troublesome as the â-lactams are a safe and effective class of antimicrobials for treating susceptible staphylococcal infections in both human beings and dogs. Additionally, resistance to other antimicrobial classes such as the macrolides, tetracyclines, sulfonamides and chloramphenicol, further complicates the treatment of staphylococcal infections. Particularly in small animal private practice, infections are often treated empirically, requiring knowledge of locally prevalent susceptibility patterns. The emergence of resistance to commonly used drugs necessitates surveillance to monitor the dissemination of resistance, and to guide antimicrobial therapy. In the last decade there have been many studies attempting to address gaps in our knowledge of the ecology of S. aureus and S. pseudintermedius in dogs. In particular, the prevalence of colonization with methicillin resistant staphylococci has been documented in different dog populations. However, failing to sample all relevant sites of colonization, may have decreased the sensitivity of these studies. The sites where coagulase positive staphylococci colonize dogs have not been systematically evaluated. The clinical and infection control implications of S. aureus infections, or colonization in the case of MRSA, requires timely laboratory identification. The tube coagulase test is arguably the most important tool used for identifying of staphylococcal species. Studies dating from the 1970s and 1980s suggested that the use of rabbit plasma, which is the current standard, may not be the ideal media for all situations and that different plasmas may need to be considered in different diagnostic situations. In this thesis, the ecology of coagulase positive staphylococci in dogs was studied from start to finish including sample collection, bacterial identification, antimicrobial susceptibility testing and molecular epidemiological investigations. This thesis will serve as a template to be used for follow up studies or by investigators setting up a surveillance program in their region. We found that multiple sites of colonization (nares, pharynx and rectum), are involved in both S. aureus and S. pseudintermedius carriage in dogs. Single site colonized dogs were identified, suggesting that maximal screening sensitivity requires sampling multiple body sites. When canine and rabbit plasma were compared, the time until clot formation was found to be significantly shorter with canine plasma. Although, the availability of canine plasma may limit its use in the diagnostic laboratory, investigators should be aware that rabbit plasma may not be ideal for all applications of the tube coagulase test. Antimicrobial susceptibility testing of canine S. aureus and S. pseudintermedius and human S. aureus isolates was done. Consistent with previous reports from Saskatoon, the S. pseudintermedius isolates were found to be overwhelmingly susceptible: pan-susceptibility was the most common phenotype identified. Antimicrobial resistance was more common among S. aureus than S. pseudintermedius including resistance to drugs which all S. pseudintermedius were susceptible to. No resistance to vancomycin, linezolid, daptomycin or quinupristin/dalfopristin was found. All isolates remained susceptible to at least one of tetracycline, clindamycin, chloramphenicol or trimethoprim/sulfamethoxazole which are often used for treating infections caused by multidrug resistant staphylococci. Finally, DNA fingerprinting revealed that the canine and human S. aureus isolates tested did not belong to mutually exclusive populations. Using AFLP, IS-typing and spa typing, many human and canine isolates were indistinguishable suggesting a common population, supporting the hypothesis that interspecies transmission occurs. The complex and under-characterized ecology of S. aureus and S. pseudintermedius requires more study so that risk factors for infection can be defined and effective infection control measures implemented. Because multiple species are involved, collaboration between veterinarians and human health professionals is imperative, and will no doubt yield the most success in our efforts to understand these potential pathogens.

Staphylococcus aureus is one of the most important pathogens both in community- or hospital-acquired infections. The first part of this study analyzed the similarity of molecular types of S. aureus isolates cultured from nares and blood in patients with S. aureus bacteremia (SAB) by pulse-fielded gel electrophoresis (PFGE) of digested chromosomal DNA by Sma I at Kaohsiung Veterans General Hospital from August 1, 2000 through July 31, 2001. The results showed that the PFGE types of 78 (82.1%) paired nare and blood isolates of the 95 SAB patients having nasal carriage of S. aureus were clonally identical; identical in 89.7% patients of nosocomial group and 62.9% in community-acquired group. This provides the powerful evidence in close relationship between nasal carriage of S. aureus and acquisition of it in bacteremia. The data also showed that the rate of methicillin resistance occurred in SAB patients with nasal carriage in isolates of nosocomial SAB was 85.3%, and 31.3% in community-acquired group. The second part of this study analyzed the distribution of PFGE types of 163 nosocomial SAB isolates. The most predominant type was type A and composed 51.5% (84 strains) of 163 nosocomial SAB isolates. They were further divided into 7 subtypes. The second prevailing type was type B, 6.1%(10 strains). The evidence that an endemic stain (type A) occurred in >50% of nosocomial bacteremic isolates demonstrates horizontal dissemination of a single endemic strain of S. aureus in the SAB patients was common in the hospital. These results provide support for strategies to endorse more intensive procedures in infection control and to prevent systemic S. aureus infections by eliminating S. aureus nasal carriage.