No abstract

Multidrug-resistant K. pneumoniae producing OXA-48-like carbapenemase are emerging as important pathogens in Spain due to intra- and inter-hospital, clonal and non-clonal dissemination.

Acinetobacter baumannii is one of the major pathogens involved in nosocomial outbreaks. The clonal diversity of 729 epidemic strains isolated from 19 Spanish hospitals (mainly from intensive care units) was analyzed over an 11-year period. Pulsed-field gel electrophoresis (PFGE) identified 58 PFGE types that were subjected to susceptibility testing, rpoB gene sequencing, and multilocus sequence typing (MLST). All PFGE types were multidrug resistant; colistin was the only agent to which all pathogens were susceptible. The 58 PFGE types were grouped into 16 clones based on their genetic similarity (cutoff of 80%). These clones were distributed into one major cluster (cluster D), three medium clusters (clusters A, B, and C), and three minor clusters (clusters E, F, and G). Multidrug-resistant Acinetobacter baumannii is a bacterium frequently endemic in certain hospital wards and is responsible for numerous nosocomial outbreaks around the world (3,23,33). Its great capacity to survive in low-moisture environments and its ability to develop resistance to antimicrobial agents afford A. baumannii the possibility of spreading in hospitals. The skin, oropharynx, and digestive tract are the main body areas colonized in hospitalized patients. The risk of colonization and subsequent infection are associated with factors such as the presence of underlying severe illnesses, long-term hospitalization, stays in specific hospital wards, selective antimicrobial pressure, and invasive interventions such as the use of mechanical ventilation or catheters (4,12,14,18).Nosocomial outbreaks of A. baumannii can have their origin in a single reservoir or in multiple contaminated sites (37, 39), and infection can have serious repercussions for patient morbidity and mortality. Patients can acquire the bacterium from an environmental source or from other patients (6, 18).The clonal study of hospital strains is very important in terms of an understanding of the epidemiology of these outbreaks. The aim of the present work was therefore to analyze the genetic diversity and clonal distribution of epidemic strains of A. baumannii isolated from around Spain over a long period of time. Isolates collected during outbreaks at different hospitals were analyzed by pulsed-field gel electrophoresis (PFGE), sequencing of the RNA polymerase ␤ subunit (rpoB) gene, and multilocus sequence typing (MLST). The results were then compared. Antimicrobial susceptibility testing was also performed to determine the multidrug resistance phenotypes of these epidemic strains. MATERIALS AND METHODSBacterial strains. Over the 11-year period from 1997 to 2007, an initial 814 A. baumannii strains isolated from clinical settings and suspected of being involved in nosocomial outbreaks were sent to the Spanish National Center for Microbiology (CNM) for typing. Strains were isolated from 19 public hospitals in 17 Spanish provinces. Hospitals were coded H1 to H19, and provinces were coded P1 to P17. The type of clinical sample, the hospital ward of origin, and the isolation per...

BackgroundCommunity-associated methicillin-resistant Staphylococcus aureus-(CA-MRSA) strains have emerged in Argentina. We investigated the clinical and molecular evolution of community-onset MRSA infections (CO-MRSA) in children of Córdoba, Argentina, 2005–2008. Additionally, data from 2007 were compared with the epidemiology of these infections in other regions of the country.Methodology/Principal FindingsTwo datasets were used: i) lab-based prospective surveillance of CA-MRSA isolates from 3 Córdoba pediatric hospitals-(CBAH1-H3) in 2007–2008 (compared to previously published data of 2005) and ii) a sampling of CO-MRSA from a study involving both, healthcare-associated community-onset-(HACO) infections in children with risk-factors for healthcare-associated infections-(HRFs), and CA-MRSA infections in patients without HRFs detected in multiple centers of Argentina in 2007. Molecular typing was performed on the CA-MRSA-(n: 99) isolates from the CBAH1-H3-dataset and on the HACO-MRSA-(n: 51) and CA-MRSA-(n: 213) isolates from other regions. Between 2005–2008, the annual proportion of CA-MRSA/CA-S. aureus in Córdoba hospitals increased from 25% to 49%, P<0.01. Total CA-MRSA infections increased 3.6 fold-(5.1 to 18.6 cases/100,000 annual-visits, P<0.0001), associated with an important increase of invasive CA-MRSA infections-(8.5 fold). In all regions analyzed, a single genotype prevailed in both CA-MRSA (82%) and HACO-MRSA(57%), which showed pulsed-field-gel electrophoresis-(PFGE)-type-“I”, sequence-type-5-(ST5), SCCmec-type-IVa, spa-t311, and was positive for PVL. The second clone, pulsotype-N/ST30/CC30/SCCmecIVc/t019/PVL+, accounted for 11.5% of total CA-MRSA infections. Importantly, the first 4 isolates of Argentina belonging to South American-USA300 clone-(USA300/ST8/CC8/SCCmecIVc/t008/PVL+/ACME−) were detected. We also demonstrated that a HA-MRSA clone-(pulsotype-C/ST100/CC5) caused 2% and 10% of CA-MRSA and HACO-MRSA infections respectively and was associated with a SCCmec type closely related to SCCmecIV(2B&5).Conclusions/SignificanceThe dissemination of epidemic MRSA clone, ST5-IV-PVL+ was the main cause of increasing staphylococcal community-onset infections in Argentinean children (2003–2008), conversely to other countries. The predominance of this clone, which has capacity to express the h-VISA phenotype, in healthcare-associated community-onset cases suggests that it has infiltrated into hospital-settings.