Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Cystic Fibrosis Patients from Argentina

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in cystic fibrosis (CF) patients is an increasing problem in many countries. In our Respiratory Center at the Hospital de Niños "Dr. Ricardo Gutiérrez", Buenos Aires, Argentina, the prevalence has climbed from 23% in 1995 up to 32% in 2011. Our objective was to analyze the diversity of MRSA isolates recovered from respiratory samples of CF patients attending our center, characterizing their phenotypes and clonal distribution. Therefore, a prospective study was conducted on all CF patients attending the pediatric Respiratory Center between June 2012 and May 2013 to collect MRSA isolates. Antibiotic susceptibility testing, multilocus sequence typing, pulsed-field gel electrophoresis, spa typing, and agr genotyping were performed on collected isolates. The prevalence of MRSA during this period was 34.2%, and 71.9% of the patients were infected with isolates that carried SCCmec IV. High resistance rates were detected for gentamicin, erythromycin, clindamycin, ciprofloxacin, and rifampicin. Strains related to the community-associated MRSA clones, ST5-IV and ST30-IV, were the most frequently recovered. Remarkably, even though most of the isolates were related to these clones, the rate of multi-resistance shown in CF patients was higher than that reported for the same lineages recovered from other infections in our country.

Molecular characterisation of methicillin-resistant Staphylococcus aureus from chronically colonised cystic fibrosis paediatric patients in Brazil

“…Likewise, the great majority (72.4%) of our isolates were SCC mec IV and proved to be more susceptible to the non- β -lactam antibiotics tested. Other studies in MRSA colonised CF patients have also reported a high prevalence of SCC mec IV [ 23 , 26 ]. This finding was expected as the latter element was also frequent among CF MRSA isolates from a previous study by our group [ 9 ].…”

“…According to the American Cystic Fibrosis Registry, between 2000 and 2010, the prevalence of MRSA in CF patients has increased dramatically [ 2 ] and in recent years it has been suggested that the possibility of MRSA eradication in CF patients presenting with chronic infection is significantly lower when compared to patients with intermittent colonisation [ 21 ]. Epidemiological typing studies of MRSA in chronically infected CF patients are relatively scarce [ 22 , 23 ] and such data, particularly from longitudinal studies, remain necessary to better understand the patterns of acquisition and dynamics of strain populations over time. Regarding antibiotic susceptibility, the high resistance rates to erythromycin, ciprofloxacin and clindamycin observed in our study were consistent with the literature on MRSA from many different types of infections [ 24 , 25 ].…”

“…In this study, only 10 (8.2%) isolates from four of the 12 patients were positive for PVL genes and all of them harboured SCC mec IV, which is frequently associated with toxin-producing strains [ 30 ]. Although a low frequency of PVL positive isolates has been reported in CF patients [ 22 , 23 , 31 ], such strains are more likely to be associated with lung inflammation as the toxin is considered a potent inducer of inflammation and cytotoxicity [ 16 , 32 ].…”

“…There are relatively few studies in patients with CF infected with MRSA that have documented the permanence of strain lineages over time [ 11 , 23 , 26 ]. The majority of our patients harboured different pulsotypes and this was particularly evident for the predominant spa type t002.…”

Molecular Characteristics of Community-Associated Staphylococcus aureus Isolates From Pediatric Patients With Bloodstream Infections Between 2012 and 2017 in Shanghai, China

“…The incidence of CA-SA infections is higher in children ( Huang and Chen, 2011 ). Although CA-SA infection and transmission has become a serious public health problem worldwide ( David et al, 2015 ; McMullan et al, 2016 ; Pena Amaya et al, 2017 ; Kang et al, 2017 ; Roediger et al, 2017 ), the information regarding CA-SA associated with bloodstream infections (BSIs) in children in China is still very limited. The aim of this study was to investigate the molecular profile, antimicrobial resistance, and virulence genes associated with 78 CA-SA isolates recovered from pediatric patients with BSIs between 2012 and 2017 in a hospital in China.…”