Beta-lactamase-producing (Bla+) enterococci have been reported in three state and two countries. Pulsed-field gel electrophoresis was used to compare 14 Bla+ Enterococcus (Streptococcus) faecalis isolated from hospitalized patients in seven states and three continents. The restriction endonuclease digestion patterns of isolates from Connecticut, Massachusetts, Lebanon, and Argentina were all markedly different, indicating that these were different strains. However, isolates from Delaware, Texas, Pennsylvania (Philadelphia and Pittsburgh), Florida, and Virginia were similar, indicating that these isolates were derivatives of a single strain. This conclusion was supported by hybridization using individual fragments as probes. Spread of Bla+ enterococci within the hospital setting was also demonstrated. These findings illustrate the value of pulsed-field gel electrophoresis for epidemiologic analyses and support the importance of identifying and containing organisms with new resistance properties in an effort to decrease their transmission to and from, as well as within, hospitals.

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.

During a 6-month period, 95 invasive infections due to Streptococcus pyogenes and group C or group G Streptococcus dysgalactiae subsp. equisimilis were recorded from 40 centers of 16 cities in Argentina. We describe here epidemiologic data available for 55 and 19 patients, respectively, associated with invasive infections due to S. pyogenes and S. dysgalactiae subsp. equisimilis. The associated isolates and 58 additional pharyngeal isolates were genotyped and subjected to serologic and/or antibiotic susceptibility testing. Group A streptococcal emm type distribution and strain association with toxic shock appeared to differ somewhat from results found within the United States; however, serologic characterization and sof sequence typing suggested that emm types found in both countries are reflective of shared clonal types.

There is little information about invasive infections by group B streptococci (GBS) and their antimicrobial susceptibilities in Latin America. We performed a prospective multicenter study to determine the serotype distribution and the antimicrobial susceptibility of GBS in Argentina. We identified 58 cases, but only 44 had sufficient data to be evaluated. Eight early-, four late-, and one fatal late, late-onset neonatal infections due to GBS were found. A total of 31 patients were adults with bacteremia, skin and soft tissue infections, osteomyelitis, arthritis, meningitis, abdominal infections, and renal abscess. Serotype III was prevalent in late-onset neonatal disease, and several serotypes (Ia/c, III, Ia, and II) were involved in early-onset neonatal infections. Serotypes II, Ia/c, III, and IV were commonly found in adults, with serotype II prevalent in younger adults (18 to 69 years old) and serotype Ia/c prevalent in elderly adults (>70 years old). The mortality rate attributable to GBS infections was 10.8%. All GBS were susceptible to penicillin and ceftriaxone. Resistance to clindamycin (1.7%), erythromycin (5.2%), azithromycin (5.2%), minocycline (69%), and tetracycline (72.4%), to high levels of kanamycin and amikacin (1.7%), and to intermediately high levels of gentamicin (1.7%) was observed. The bifunctional enzyme AAC6-APH2؆ was detected in the isolate resistant to aminoglycosides, and other genetic determinants were identified in other resistant isolates: tetM and tetO in tetracycline-resistant streptococci and mefA and ermTR for efflux-mediated and inducible macrolide-lincosamide-streptogramin B-resistant streptococci, respectively. For clinical purposes and rapid and easy detection of high-level aminoglycoside-resistant GBS, a screening method that used 1,000-g kanamycin disks is proposed.

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Six beta-lactamase-producing (Bla+) isolates of Enterococcus faecalis recovered over a 17-month period from an Argentinian pediatric hospital were found to have identical or almost identical chromosomal restriction patterns by pulsed-field gel electrophoresis, although the plasmid patterns were different. These isolates, like Bla+ enterococci in the United States, hybridized to a staphylococcal Bla gene probe. The presence of a single strain was somewhat surprising, since all isolates transferred Bla by conjugation.

beta-Lactamases with pIs of 5.4 and 8.1 were detected by hydrolysis of ampicillin and ceftriaxone respectively among cefotaxime resistant serovars of Salmonella spp. suggesting TEM-1 and an unidentified extended spectrum beta-lactamase have spread throughout these strains in Argentina.

Enterococci are intrinsically resistant to several antimicrobial classes and show a great ability to acquire new mechanisms of resistance. Resistance to β-lactam antibiotics is a major concern because these drugs either alone or in combination are commonly used for the treatment of enterococcal infections. Ampicillin resistance, which is rare in Enterococcus faecalis, occurs in most of the hospital-associated Enterococcus faecium isolates. High-level resistance to ampicillin in E. faecium is mainly due to the enhanced production of PBP5 and/or by polymorphisms in the beta subunit of this protein. The dissemination of high-level ampicillin resistance can be the result of both clonal spread of strains with mutated pbp5 genes and horizontal gene transfer.