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A population-based study examining the emergence of community-associated methicillin-resistant Staphylococcus aureus USA300 in New York City
Simona Bratu, David Landman, Jyoti Gupta, Manoj Trehan, Monica Panwar, John Quale
Annals of Clinical Microbiology and Antimicrobials , 2006, DOI: 10.1186/1476-0711-5-29
Abstract: All unique patient isolates of S. aureus were collected from hospitals in Brooklyn, NY over a three-month period. Isolates of MRSA that were susceptible to clindamycin underwent SCCmec typing. Isolates with the SCCmec type IV (characteristic of CA-MRSA strains) underwent ribotyping. Demographic information involving the neighborhoods of Brooklyn was also gathered and correlated with the prevalence of CA-MRSA strains.Of 1316 isolates collected during the surveillance, 217 were MRSA susceptible to clindamycin. A total of 125 isolates possessed SCCmec type IV; 72 belonged to the USA300 strain and five belonged to the USA400 strain. Hospitals in the eastern part of the city had the highest prevalence of USA300 strain. Individuals in the eastern region, when compared to the western region, were more likely to be Black, Hispanic, female, and < 18 years of age, and to have households of ≥ 3 persons. In addition, the median household income was lower, and the proportion of individuals on public assistance was higher, for the population in the eastern region.The USA300 strain of CA-MRSA is emerging in New York City. In this population-based study, urban regions of lower socioeconomic status and with evidence of overcrowding appear to be at higher risk for the emergence of this pathogen.Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a frequent and serious pathogen in several regions in the United States. The CA-MRSA strains have distinctive phenotypic and genotypic features when compared to typical hospital-acquired strains. Most CA-MRSA remain susceptible to other non-β-lactam antibiotics [1-4]. CA-MRSA strains typically possess type IV SCCmec gene and the Panton-Valentine leukocidin (PVL)[1,4,5]. Two distinctive pulsed field gel electrophoresis types of CA-MRSA have predominated in the United States [1]. The USA400 type was isolated from children in the Midwestern United States, and has been associated with nosocomial infections in
Emergence of Daptomycin Resistance in Daptomycin-Na?ve Rabbits with Methicillin-Resistant Staphylococcus aureus Prosthetic Joint Infection Is Associated with Resistance to Host Defense Cationic Peptides and mprF Polymorphisms  [PDF]
Nagendra N. Mishra, Soo-Jin Yang, Liang Chen, Claudette Muller, Azzam Saleh-Mghir, Sebastian Kuhn, Andreas Peschel, Michael R. Yeaman, Cynthia C. Nast, Barry N. Kreiswirth, Anne-Claude Crémieux, Arnold S. Bayer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071151
Abstract: Background Previous studies of both clinically-derived and in vitro passage-derived daptomycin–resistant (DAP-R) Staphylococcus aureus strains demonstrated the coincident emergence of increased DAP MICs and resistance to host defense cationic peptides (HDP-R). Methods In the present investigation, we studied a parental DAP-susceptible (DAP-S) methicillin-resistant Staphylococcus aureus (MRSA) strain and three isogenic variants with increased DAP MICs which were isolated from both DAP-treated and DAP-untreated rabbits with prosthetic joint infections. These strains were compared for: in vitro susceptibility to distinct HDPs differing in size, structure, and origin; i.e.; thrombin-induced platelet microbicidal proteins [tPMPs] and human neutrophil peptide-1 [hNP-1]; cell membrane (CM) phospholipid and fatty acid content; CM order; envelope surface charge; cell wall thickness; and mprF single nucleotide polymorphisms (SNPs) and expression profiles. Results In comparison with the parental strain, both DAP-exposed and DAP-naive strains exhibited: (i) significantly reduced susceptibility to each HDP (P<0.05); (ii) thicker cell walls (P<0.05); (iii) increased synthesis of CM lysyl-phosphatidylglycerol (L-PG); (iv) reduced content of CM phosphatidylglycerol (PG); and (v) SNPs within the mprF locus No significant differences were observed between parental or variant strains in outer CM content of L-PG, CM fluidity, CM fatty acid contents, surface charge, mprF expression profiles or MprF protein content. An isolate which underwent identical in vivo passage, but without evolving increased DAP MICs, retained parental phenotypes and genotype. Conclusions These results suggest: i) DAP MIC increases may occur in the absence of DAP exposures in vivo and may be triggered by organism exposure to endogenous HDPs: and ii) gain-in-function SNPs in mprF may contribute to such HDP-DAP cross-resistance phenotypes, although the mechanism of this relationship remains to be defined.
Empyema necessitans and acute osteomyelitis associated with community acquired methicillin resistant Staphylococcus aureus in an infant
Contreras,Germán A; Pérez,Norma; Murphy,James R; Cleary,Thomas G; Heresi,Gloria P;
Biomédica , 2009,
Abstract: staphylococcus aureus is a well recognized pathogen with global distribution. in recent years community-associated, methicillin-resistant s. aureus has emerged as an increasing cause of severe infections among adults and children. herein, a case is reported of a previously healthy, 19-month-old male, who presented with empyema necessitans and acute osteomyelitis due to a community-associated, methicillin-resistant, s. aureus strain. this report highlights the evolving epidemiology of s. aureus, as important pathogen in the community as well as the hospital setting, and the importance of establishing appropriate guidelines for diagnosis, management and surveillance of this public health problem.
Methicillin-Susceptible Staphylococcus aureus as a Predominantly Healthcare-Associated Pathogen: A Possible Reversal of Roles?  [PDF]
Michael Z. David,Susan Boyle-Vavra,Diana L. Zychowski,Robert S. Daum
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018217
Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) strains have become common causes of skin and soft tissue infections (SSTI) among previously healthy people, a role of methicillin-susceptible (MSSA) isolates before the mid-1990s. We hypothesized that, as MRSA infections became more common among S. aureus infections in the community, perhaps MSSA infections had become more important as a cause of healthcare-associated infection.
Clinical and Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in New Zealand: Rapid Emergence of Sequence Type 5 (ST5)-SCCmec-IV as the Dominant Community-Associated MRSA Clone  [PDF]
Deborah A. Williamson, Sally A. Roberts, Stephen R. Ritchie, Geoffrey W. Coombs, John D. Fraser, Helen Heffernan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062020
Abstract: The predominant community-associated MRSA strains vary between geographic settings, with ST8-IV USA300 being the commonest clone in North America, and the ST30-IV Southwest Pacific clone established as the dominant clone in New Zealand for the past two decades. Moreover, distinct epidemiological risk factors have been described for colonisation and/or infection with CA-MRSA strains, although these associations have not previously been characterized in New Zealand. Based on data from the annual New Zealand MRSA survey, we sought to describe the clinical and molecular epidemiology of MRSA in New Zealand. All non-duplicate clinical MRSA isolates from New Zealand diagnostic laboratories collected as part of the annual MRSA survey were included. Demographic data was collected for all patients, including age, gender, ethnicity, social deprivation index and hospitalization history. MRSA was isolated from clinical specimens from 3,323 patients during the 2005 to 2011 annual surveys. There were marked ethnic differences, with MRSA isolation rates significantly higher in Māori and Pacific Peoples. Over the study period, there was a significant increase in CA-MRSA, and a previously unidentified PVL-negative ST5-IV spa t002 clone replaced the PVL-positive ST30-IV Southwest Pacific clone as the dominant CA-MRSA clone. Of particular concern was the finding of several successful and virulent MRSA clones from other geographic settings, including ST93-IV (Queensland CA-MRSA), ST8-IV (USA300) and ST772-V (Bengal Bay MRSA). Ongoing molecular surveillance is essential to prevent these MRSA strains becoming endemic in the New Zealand healthcare setting.
Nasal carriage of methicillin-resistant Staphylococcus aureus in university students
Prates, Karina Aparecida;Torres, Ana Maria;Garcia, Lourdes Botelho;Ogatta, Sueli Fumie Yamada;Cardoso, Celso Luiz;Tognim, Maria Cristina Bronharo;
Brazilian Journal of Infectious Diseases , 2010, DOI: 10.1590/S1413-86702010000300021
Abstract: in a study of university students, the percentage nasal carriage of staphylococcus aureus was 40.8% (102/250). of the isolates, mic50 of methicillin was 0.5 μg/ml and mic90 was 1 μg/ml. six (5.8%) isolates were methicillin-resistant and carried the meca gene. these results suggest that community-associated methicillin-resistant s. aureus may be spreading in brazil.
Capsaicin Protects Mice from Community-Associated Methicillin-Resistant Staphylococcus aureus Pneumonia  [PDF]
Jiazhang Qiu, Xiaodi Niu, Jianfeng Wang, Yan Xing, Bingfeng Leng, Jing Dong, Hongen Li, Mingjing Luo, Yu Zhang, Xiaohan Dai, Yonghuang Luo, Xuming Deng
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033032
Abstract: Background α-toxin is one of the major virulence factors secreted by most Staphylococcus aureus strains, which played a central role in the pathogenesis of S. aureus pneumonia. The aim of this study was to investigate the impact of capsaicin on the production of α-toxin by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain USA 300 and to further assess its performance in the treatment of CA-MRSA pneumonia in a mouse model. Methodology/Principal Findings The in vitro effects of capsaicin on α-toxin production by S. aureus USA 300 were determined using hemolysis, western blot, and real-time RT-PCR assays. The influence of capsaicin on the α-toxin-mediated injury of human alveolar epithelial cells was determined using viability and cytotoxicity assays. Mice were infected intranasally with S. aureus USA300; the in vivo protective effects of capsaicin against S. aureus pneumonia were assessed by monitoring the mortality, histopathological changes and cytokine levels. Low concentrations of capsaicin substantially decreased the production of α-toxin by S. aureus USA 300 without affecting the bacterial viability. The addition of capsaicin prevented α-toxin-mediated human alveolar cell (A549) injury in co-culture with S. aureus. Furthermore, the in vivo experiments indicated that capsaicin protected mice from CA-MRSA pneumonia caused by strain USA 300. Conclusions/Significance Capsaicin inhibits the production of α-toxin by CA-MRSA strain USA 300 in vitro and protects mice from CA-MRSA pneumonia in vivo. However, the results need further confirmation with other CA-MRSA lineages. This study supports the views of anti-virulence as a new antibacterial approach for chemotherapy.
Community-associated Methicillin-resistant Staphylococcus aureus Bacteremia and Endocarditis among HIV Patients: A cohort study
Jon P Furuno, Jennifer K Johnson, Marin L Schweizer, Anayochukwu Uche, Oscar C Stine, Simone M Shurland, Graeme N Forrest
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-298
Abstract: All adult HIV-infected patients with documented S. aureus bacteremia admitted to the University of Maryland Medical Center between January 1, 2003 and December 31, 2005 were included. CA-MRSA was defined as a USA300 MRSA isolate with the MBQBLO spa-type motif and positive for both the arginine catabolic mobile element and Panton-Valentin Leukocidin. Risk factors for S. aureus-associated infective endocarditis and mortality were determined using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). Potential risk factors included demographic variables, comorbid illnesses, and intravenous drug use.Among 131 episodes of S. aureus bacteremia, 85 (66%) were MRSA of which 47 (54%) were CA-MRSA. Sixty-three patients (48%) developed endocarditis and 10 patients (8%) died in the hospital on the index admission Patients with CA-MRSA were significantly more likely to develop endocarditis (OR = 2.73, 95% CI = 1.30, 5.71). No other variables including comorbid conditions, current receipt of antiretroviral therapy, pre-culture severity of illness, or CD4 count were significantly associated with endocarditis and none were associated with in-hospital mortality.CA-MRSA was significantly associated with an increased incidence of endocarditis in this cohort of HIV patients with MRSA bacteremia. In populations such as these, in which the prevalence of intravenous drug use and probability of endocarditis are both high, efforts must be made for early detection, which may improve treatment outcomes.Staphylococcus aureus bacteremia is a serious health condition associated with considerable morbidity and mortality among infected patients [1]. Negative outcomes associated with S. aureus bacteremia include prolonged hospital stay, endocarditis, sepsis, and death [1,2]. The changing epidemiology of S. aureus, including the increasing incidence and prevalence of methicillin-resistant S. aureus (MRSA) and the emergence of community-associated MRSA (CA-MRSA) further
European ST80 community-associated methicillin-resistant Staphylococcus aureus orbital cellulitis in a neonate
Evangelia E Tsironi, Fani Zacharaki, Ioanna N Grivea, Sophia V Tachmitzi, Aspasia N Michoula, Marianna Vlychou, Efthimia Petinaki, George A Syrogiannopoulos
BMC Ophthalmology , 2012, DOI: 10.1186/1471-2415-12-7
Abstract: A 28-day-old Caucasian boy was referred to our hospital with the diagnosis of right orbital cellulitis. His symptoms included right eye proptosis, periocular edema and redness. Empirical therapy of intravenous daptomycin, rifampin and ceftriaxone was initiated. The culture of pus yielded a methicillin-resistant S. aureus isolate and the molecular analysis revealed that it was a Panton-Valentine leukocidine-positive ST80 strain. The combination antimicrobial therapy was continued for 42 days and the infection was successfully controlled.Clinicians should be aware that young infants, even without any predisposing condition, are susceptible to orbital cellulitis caused by community-associated methicillin-resistant S. aureus. Prompt initiation of the appropriate empirical therapy, according to the local epidemiology, should successfully address the infection, preventing ocular and systemic complications.Over the past 2 decades, the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections has constantly been rising, due to the emergence of highly virulent and transmissible strains [1]. In a recent study performed in our area, CA-MRSA was found to be increasing as a cause of skin and soft tissue infections, as well as of the invasive ones, among all pediatric ages [2]. Fortunov et al. have reported that CA-MRSA infections are also increasing in previously healthy neonates without traditional risk factors and males are most often affected between 7 to 12 days of age [3,4].Greece is a country with increased incidence of CA-MRSA. This expansion is associated mainly with the wide spread in the community of a single virulent clone, the European ST80. In our area, the proportion of staphylococcal pediatric infections caused by a CA-MRSA isolate increased from 51.5% in 2003-2006 to 63.4% in 2007-2009 [2]. In addition, an increasing rate of resistance to clindamycin has been noted. The rate of clindamycin resistance in MRSA isolates betwe
Methicillin Resistance Alters the Biofilm Phenotype and Attenuates Virulence in Staphylococcus aureus Device-Associated Infections  [PDF]
Clarissa Pozzi equal contributor,Elaine M. Waters equal contributor,Justine K. Rudkin,Carolyn R. Schaeffer,Amanda J. Lohan,Pin Tong,Brendan J. Loftus,Gerald B. Pier,Paul D. Fey,Ruth C. Massey,James P. O'Gara
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002626
Abstract: Clinical isolates of Staphylococcus aureus can express biofilm phenotypes promoted by the major cell wall autolysin and the fibronectin-binding proteins or the icaADBC-encoded polysaccharide intercellular adhesin/poly-N-acetylglucosamine (PIA/PNAG). Biofilm production in methicillin-susceptible S. aureus (MSSA) strains is typically dependent on PIA/PNAG whereas methicillin-resistant isolates express an Atl/FnBP-mediated biofilm phenotype suggesting a relationship between susceptibility to β-lactam antibiotics and biofilm. By introducing the methicillin resistance gene mecA into the PNAG-producing laboratory strain 8325-4 we generated a heterogeneously resistant (HeR) strain, from which a homogeneous, high-level resistant (HoR) derivative was isolated following exposure to oxacillin. The HoR phenotype was associated with a R602H substitution in the DHHA1 domain of GdpP, a recently identified c-di-AMP phosphodiesterase with roles in resistance/tolerance to β-lactam antibiotics and cell envelope stress. Transcription of icaADBC and PNAG production were impaired in the 8325-4 HoR derivative, which instead produced a proteinaceous biofilm that was significantly inhibited by antibodies against the mecA-encoded penicillin binding protein 2a (PBP2a). Conversely excision of the SCCmec element in the MRSA strain BH1CC resulted in oxacillin susceptibility and reduced biofilm production, both of which were complemented by mecA alone. Transcriptional activity of the accessory gene regulator locus was also repressed in the 8325-4 HoR strain, which in turn was accompanied by reduced protease production and significantly reduced virulence in a mouse model of device infection. Thus, homogeneous methicillin resistance has the potential to affect agr- and icaADBC-mediated phenotypes, including altered biofilm expression and virulence, which together are consistent with the adaptation of healthcare-associated MRSA strains to the antibiotic-rich hospital environment in which they are frequently responsible for device-related infections in immuno-compromised patients.
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