Effect of a Silver Nanoparticles Solution on Staphylococcus aureus and Candida spp.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Epidemiologia molecular e estudo dos fatores de virulência de Staphylococcus aureus resistentes à oxacilina isolados de feridas em pacientes atendidos em unidades básicas de saúde da cidade de Botucatu

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Low rate of methicillin-resistant coagulase-positive staphylococcal colonization of veterinary personnel in Hong Kong

Elevated rates of methicillin-resistant Staphylococcus aureus (MRSA) carriage have been reported in veterinary personnel, suggesting an occupational colonization risk. Hong Kong veterinary personnel (n = 150) were sampled for coagulase-positive staphylococci (CPS) nasal colonization. Risk factors for colonization were assessed by questionnaire. Isolates were identified and antibiotic susceptibility determined. All CPS isolates were investigated for mecA carriage, SCCmec type and PVL genes. Two subjects were colonized with methicillin-resistant CPS: one with MRSA (spa type t002 (CC5), SCCmec type II) and one with methicillin-resistant Staphylococcus pseudintermedius (MRSP) (MLST type ST71, SCCmec type II-III). MLST type ST71 S. pseudintermedius strain is the predominant MRSP clone circulating in dogs in Europe and in Hong Kong. The low MR-CPS colonization rate may be associated with low levels of large animal exposure or low rates of MRSA colonization of companion animals in Hong Kong. Colonization with non-aureus CPS, which may cause human infection, must also be considered in veterinary personnel.

Effectiveness of meticillin-resistant Staphylococcus aureus decolonization in long-term haemodialysis patients: a systematic review and meta-analysis.

BACKGROUND Chronic haemodialysis patients are a high-risk population for meticillin-resistant Staphylococcus aureus (MRSA) colonization, which is a precursor of infection. AIM To summarize the effect of nasal (± whole-body wash) MRSA decolonization in haemodialysis patients by means of a systematic review and meta-analysis. METHODS We identified eligible studies using Medline, Embase, the Cochrane database, clinicaltrials.org, and conference abstracts investigating the success of MRSA decolonization in haemodialysis patients. For the statistical analysis, we used Stata 13 to express study-specific proportions with 95% confidence intervals. A likelihood ratio test was used to assess inter-study heterogeneity. FINDINGS Six published prospective cohort studies and one study described in a conference abstract met our inclusion criteria. From 1150 haemodialysis patients enrolled in these studies, MRSA was isolated from nasal swabs of 147 (12.8%) patients. Six of the trials used mupirocin nasal ointment and combined it with chlorhexidine body washes for decolonization. The most widely used protocol was a five-day course of mupirocin nasal ointment application three times a day, and chlorhexidine body wash once daily. The pooled success rate of decolonization was 0.88 (95% confidence interval: 0.75-0.95). A likelihood ratio test of the fixed versus the random-effects model showed significant inter-study heterogeneity (P = 0.047). Four of seven studies determined subsequent MRSA infections in 94 carriers overall, two (2%) of which experienced infection. CONCLUSION The use of mupirocin together with whole-body decolonization is highly effective in eradicating MRSA carriage in haemodialysis patients. The current literature, however, is characterized by a lack of comparative effectiveness studies for this intervention.

Characterization of Staphylococcus aureus isolates associated with pediatric carriage in Houston, Texas

Infections caused by Methicillin-resistant Staphylococcus aureus (MRSA) have been of great concern in hospitals due the difficulty in treating virulent, antibiotic resistant microorganisms in sensitive populations including children, the elderly, and immunocomprimised individuals. Since the late 1990's, MRSA infections have become a problem in the general community, and the strains of S. aureus that cause infections in the community are known to be genetically different than the hospital acquired strains. Community-acquired strains tend to be more virulent, affecting even relatively healthy individuals, and disease presentation tends to be more diverse than diseases observed in patients suffering from hospital-acquired strains. From the year 2000 to the present, there has been a significant increase in community-acquired infections in children, a population already particularly sensitive to S. aureus infection. Genotyping the strains of CA-MRSA circulating in the pediatric population is an important step in developing better antibiotic treatment strategies. Additionally, determining the carriage status of individuals in this population and comparing these data with strain genotypes will also be valuable in establishing prevention and control practices. ^

Assessing pediatric nasal carriage of S. aureus & MRSA

Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) has become an increasing problem in the community. Nasal carriage of these bacteria has been shown to be a predisposing factor for infection and environmental contamination. This serious public health concern prompted an investigation to assess the pediatric nasal carriage of these bacteria in an effort to better understand the populations at risk and prevention of infection.^ This prospective study surveys 30 children from the Northwest Assistance Ministries (NAM) pediatric clinic from October 2008 to the present. Two nasal swabs were taken in 2-4 week intervals to determine S. aureus carrier status. Microbiologic tests were conducted to isolate and identify S. aureus from nasal cultures. Children with 2 cultures positive for S. aureus were classified as persistent carriers, those with 1 positive and 1 negative culture were classified as intermittent carriers, and those with 2 negative cultures were classified as noncarriers. This information was related to patient records and statistical analyses (X 2 and t-tests) were performed.^ Distribution of S. aureus carriage related to patient demographics (age, sex, & race) was showed no significant differences between S. aureus positive and S. aureus negative patient populations (p = 0.8). Additionally, the distribution of carrier status related to demographics also showed no significant difference (p = 0.8). Finally, the distribution of carrier status related to relevant medical history (immunizations current, past infection, & antibiotic use at time of swabbing) showed no significant difference (p = 0.4).^ This study is a snapshot of an ongoing study to assess the pediatric nasal carriage of S. aureus and MRSA. The inability to draw any reliable conclusion from the distribution of data is likely a result of an inadequate samples size. This is one of few studies assessing pediatric nasal carriage of S. aureus and targeting an underrepresented, Hispanic population is especially unique. Continuing this study allows for a better understanding of the epidemiology of this bacterium which will hopefully lead to appropriate interventions thus preventing future S. aureus infections.^

UK epidemic strains of meticillin-resistant Staphylococcus aureus in clinical samples from Malta

Since 1999, the European Antimicrobial Resistance Surveillance System (EARSS) has monitored the rise in infection due to a number of organisms, including meticillin-resistant Staphylococcus aureus (MRSA). The EARSS reported that MRSA infections within intensive care units account for 25-50% of infections in many central and southern European countries, these included France, Spain, Great Britain, Malta, Greece and Italy. Each country has defined epidemic MRSA (EMRSA) strains; however, the method of spread of these strains from one country to another is unknown. In this current study, DNA profiles of 473 isolates of MRSA collected from the UK and Malta were determined by PFGE. Analysis of the data showed that two countries separated by a large geographical distance had a similar DNA profile pattern. Additionally it was demonstrated that strains of EMRSA normally found in the UK were also found in the Maltese cohort (EMRSA 15 and 16). A distinct DNA profile was found in the Maltese cohort, which may be a local EMRSA, and accounted for 14.4% of all Maltese isolates. The appearance of the same MRSA and EMRSA profiles in two separate countries suggests that MRSA can be transferred out of their country of origin and potentially establish in a new locality or country.

Epidemiology of community-acquired meticillin-resistant Staphylococcus aureus obtained from the UK West Midlands region

Between January 2005 and December 2005, 199 meticillin-resistant Staphylococcus aureus (MRSA) isolates were obtained from nonhospitalised patients presenting skin and soft tissue infections to local general practitioners. The study area incorporated 57 surgeries from three Primary Care Trusts in the Lichfield, Tamworth, Burntwood, North and East Birmingham regions of Central England, UK. Following antibiotic susceptibility testing, pulsed-field gel electrophoresis, Panton-Valentine leukocidin gene detection and SCCmec element assignment, 95% of the isolates were shown to be related to hospital epidemic strains EMRSA-15 and EMRSA-16. In total 87% of the isolate population harboured SCCmec IV, 9% had SCCmec II and 4% were identified as carrying novel SCCmec IIIa-mecI. When mapped to patient home postcode, a diverse distribution of isolates harbouring SCCmec II and SCCmec IV was observed; however, the majority of isolates harbouring SCCmec IIIa-mecI were from patients residing in the north-west of the study region, highlighting a possible localised clonal group. Transmission of MRSA from the hospital setting into the surrounding community population, as demonstrated by this study, warrants the need for targeted patient screening and decolonisation in both the clinical and community environments.

Nasal carriage of Staphylococcus aureus, including community-associated methicillin-resistant strains, in Queensland adults

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are emerging in southeast Queensland, Australia, but the incidence of carriage of CA-MRSA strains is unknown. The aim of this study was to assess the nasal carriage rate of S. aureus, including CA-MRSA strains, in the general adult population of southeast Queensland. 396 patients presenting to general practices in two Brisbane suburbs and 303 volunteers randomly selected from the electoral rolls in the same suburbs completed a medical questionnaire and had nasal swabs performed for S. aureus. All isolates of S. aureus underwent antibiotic susceptibility testing and single-nucleotide polymorphism (SNP) and binary typing, including determination of Panton–Valentine leukocidin (PVL). The nasal carriage rate of methicillin-susceptible S. aureus (MSSA) was 202/699 (28%), a rate similar to that found in other community-based nasal carriage studies. According to multivariate analysis, nasal carriage of S. aureus was associated with male sex, young adult age group and Caucasian ethnicity. Only two study isolates (one MSSA and one CA-MRSA) carried PVL. The nasal carriage rate of MRSA was low, at 5/699 (0.7%), and only two study participants (0.3%) had CA-MRSA strains. CA-MRSA is an emerging cause of infection in southeast Queensland, but as yet the incidence of carriage of CA-MRSA in the general community is low.

Lack of horizontal gene transfer of methicillin-resitance genetic determinants from PBP2a-positive, coagulase-negative Staphylococci to methicillin-sensitive Staphylococcus aureus using transcutaneous electric nerve stimulation (TENS),

Previous research shows that approximately half of the coagulase-negative staphylococci (CNS) isolated from patients in the intensive care unit (ICU) at Belfast City Hospital were resistant to methicillin. The presence of this relatively high proportion of methicillin-resistance genetic material gives rise to speculation that these organisms may act as potential reservoirs of methicillinresistance genetic material to methicillin-sensitive Staphylococcus aureus (MSSA). Mechanisms of horizontal gene transfer from PBP2a-positive CNS to MSSA, potentially transforming MSSA to MRSA, aided by electroporation-type activities such as transcutaneous electrical nerve stimulation (TENS), should be considered. Methicillin-resistant CNS (MR-CNS) isolates are collected over a two-month period from a variety of clinical specimen types, particularly wound swabs. The species of all isolates are confirmed, as well as their resistance to oxacillin by standard disc diffusion assays. In addition, MSSA isolates are collected over the same period and confirmed as PBP2a-negative. Electroporation experiments are designed to mimic the time/voltage combinations used commonly in the clinical application of TENS. No transformed MRSA were isolated and all viable S. aureus cells remained susceptible to oxacillin and PBP2a-negative. Experiments using MSSA pre-exposed to sublethal concentrations of oxacillin (0.25 µg/mL) showed no evidence of methicillin gene transfer and the generation of an MRSA. The study showed no evidence of horizontal transfer of methicillin resistance genetic material from MR-CNS to MSSA. These data support the belief that TENS and the associated time/voltage combinations used do not increase conjugational transposons or facilitate horizontal gene transfer from MR-CNS to MSSA.

Estudo de staphylococcus aureus resistentes à meticilina (MRSA) por técnicas genotípicas e fenotípicas

Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

Pefloxacin therapy for experimental endocarditis caused by methicillin-susceptible or methicillin-resistant strains of Staphylococcus aureus

The therapeutic efficacy of pefloxacin in experimental endocarditis caused by methicillin-susceptible or methicillin-resistant Staphylococcus aureus was evaluated. In rabbits infected with a methicillin-susceptible strain, 4 days of pefloxacin therapy significantly reduced both the number of bacteria per gram of vegetation and the mortality rate compared with untreated controls, and pefloxacin was equivalent to cephalothin. Pefloxacin was also as effective as vancomycin in reducing vegetation titers and mortality rate in animals with endocarditis caused by a methicillin-resistant strain. These results suggest that pefloxacin may be an effective agent in the therapy of serious infections caused by either methicillin-susceptible or -resistant strains of S. aureus.

Prevalence of Staphylococcus aureus strains in an Australian cohort, 1989-2003 : evidence for the low prevalence of the toxic shock toxin and Panton-Valentine leukocidin genes

The purpose of this paper is to determine the prevalence of the toxic shock toxin gene (tst) and to enumerate the circulating strains of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in Australian isolates collected over two decades. The aim was to subtype these strains using the binary genes pvl, cna, sdrE, pUB110 and pT181. Isolates were assayed using real-time polymerase chain reaction (PCR) for mecA, nuc, 16 S rRNA, eight single-nucleotide polymorphisms (SNPs) and for five binary genes. Two realtime PCR assays were developed for tst. The 90 MRSA isolates belonged to CC239 (39 in 1989, 38 in 1996 and ten in 2003), CC1 (two in 2003) and CC22 (one in 2003). The majority of the 210 MSSA isolates belonged to CC1 (26), CC5 (24) and CC78 (23). Only 18 isolates were tst-positive and only 15 were pvl-positive. Nine MSSA isolates belonged to five binary types of ST93, including two pvlpositive types. The proportion of tst-positive and pvl-positive isolates was low and no significant increase was demonstrated. Dominant MSSA clonal complexes were similar to those seen elsewhere, with the exception of CC78. CC239 MRSA (AUS-2/3) was the predominant MRSA but decreased significantly in prevalence, while CC22 (EMRSA-15) and CC1 (WA-1) emerged. Genetically diverse ST93 MSSA predated the emergence of ST93- MRSA (the Queensland clone).

Clonal complexes and virulence factors of Staphylococcus aureus from several cities in India

Background: Diseases from Staphylococcus aureus are a major problem in Indian hospitals and recent studies point to infiltration of community associated methicillin resistant S. aureus (CA-MRSA) into hospitals. Although CA-MRSA are genetically different from nosocomial MRSA, the distinction between the two groups is blurring as CA-MRSA are showing multidrug resistance and are endemic in many hospitals. Our survey of samples collected from Indian hospitals between 2004 and 2006 had shown mainly hospital associated methicillin resistant Staphylococcus aureus (HA-MRSA) carrying staphylococcal cassette chromosome mec (SCCmec) type III and IIIA. But S. aureus isolates collected from 2007 onwards from community and hospital settings in India have shown SCCmec type IV and V cassettes while several variations of type IV SCCmec cassettes from IVa to IVj have been found in other parts of the world. In the present study, we have collected nasal swabs from rural and urban healthy carriers and pus, blood etc from in patients from hospitals to study the distribution of SCCmec elements and sequence types (STs) in the community and hospital environment. We performed molecular characterization of all the isolates to determine their lineage and microarray of select isolates from each sequence type to analyze their toxins, virulence and immune-evasion factors. Results: Molecular analyses of 68 S. aureus isolates from in and around Bengaluru and three other Indian cities have been carried out. The chosen isolates fall into fifteen STs with all major clonal complexes (CC) present along with some minor ones. The dominant MRSA clones are ST22 and ST772 among healthy carriers and patients. We are reporting three novel clones, two methicillin sensitive S. aureus (MSSA) isolates belonging to ST291 (related to ST398 which is live stock associated), and two MRSA clones, ST1208 (CC8), and ST672 as emerging clones in this study for the first time. Sixty nine percent of isolates carry Panton-Valentine Leucocidin genes (PVL) along with many other toxins. There is more diversity of STs among methicillin sensitive S. aureus than resistant ones. Microarray analysis of isolates belonging to different STs gives an insight into major toxins, virulence factors, adhesion and immune evasion factors present among the isolates in various parts of India. Conclusions: S. aureus isolates reported in this study belong to a highly diverse group of STs and CC and we are reporting several new STs which have not been reported earlier along with factors influencing virulence and host pathogen interactions.

Determinação do perfil fenotípico e genotípico de amostras de Staphylococus aureus resistentes à meticilina (MRSA) e sensíveis a antibióticos não ß-lactâmicos em cinco hospitais no município do Rio de Janeiro

Staphylococcus aureus resistente à meticilina (MRSA) é um dos principais microrganismos envolvidos nas Infecções relacionadas à Assistência à Saúde (IrAS). Porém, um clone de MRSA, o CA-MRSA, emergiu na comunidade e atualmente vem sendo agente de IrAS. O objetivo desta dissertação é avaliar fenotípica e genotipicamente 111 amostras de Staphylococcus aureus resistentes à meticilina e sensíveis a antibióticos não ß-lactâmicos de pacientes atendidos em cinco hospitais no município do Rio de Janeiro. Utilizando os critérios padronizados pelo CLSI 2012, foram determinadas as susceptibilidades a 11 antimicrobianos pelo método de disco difusão em ágar e concentração inibitória mínima para vancomicina e oxacilina pelo método da microdiluição em caldo. A multirresistência (resistência a 3 ou mais antimicrobianos não ß-lactâmicos) foi observada em 31,5% das amostras, sendo que 53,2% apresentaram resistência ao antimicrobiano clindamicina, uma das opções para o tratamento empírico das infecções de pele/tecidos moles. 86,4% apresentaram concentração inibitória mínima (CIM) para vancomicina ≥ 1,0 g/mL ou seja, elevado percentual de amostras associadas ao fenômeno MIC creep, o qual está associado ao insucesso na terapia antimicrobiana anti-MRSA. Não foi observado até o momento nenhuma amostra com CIM ≥ 4cg/mL para vancomicina, entretanto, já há resistência à linezolida em quatro hospitais do estudo. A tipificação do SCCmec nos permitiu classificar 4,5% das amostras em HA-MRSA e 86,5% em CA-MRSA, nas quais a resistência heterogênea típica à oxacilina foi observada em 57,2%. A toxina de Panton-Valentine (PVL) foi identificada pela metodologia de PCR em 28% das amostras com genótipo CA-MRSA. Os fatores de riscos clássicos, da literatura, relacionados à infecção por HA-MRSA foram também observados nos pacientes com infecção por CA-MRSA portadoras de SCCmec IV e V. No intuito de verificar a existência de similaridades genéticas ou a presença de clone predominante entre as amostras dos cinco hospitais, foi realizada a técnica de eletroforese em gel sob campo pulsado (PFGE) e observou-se diversidade genética assim como a presença de amostras com padrões similares aos clones OSPC (18,5%) e USA400. Não foram encontradas amostras com padrões de eletroforese similares aos clones USA300, USA800 e CEB. É essencial a vigilância da resistência aos antimicrobianos não ß-lactâmicos no CA-MRSA, em especial à vancomicina. A mudança na epidemiologia deste microrganismo vem impactando os padrões característicos dos genótipos limitando os critérios de diferenciação entre eles. Neste contexto, as técnicas moleculares atuam como excelentes ferramentas de caracterização. O conhecimento do patógeno auxilia na elaboração e implementação de medidas preventivas, contribuindo para o controle da doença tanto no ambiente hospitalar quanto na comunidade.