Spreading of AbaR-type genomic islands in multidrug resistance Acinetobacter baumannii strains belonging to different clonal complexes.

In order to determine the occurrence of AbaR-type genomic island in multidrug resistant Acinetobacter baumannii (MDRAb) strains circulating in Argentina, Uruguay, and Chile, we studied 51 MDRAb isolates recovered from several hospitals over 30 years. AbaR-type genomic resistance islands were found in 36 MDRAb isolates since 1986 till now. MLST technique allowed us to identify the presence of four different Clonal Complexes (109, 104, 119, 113) among the positive AbaR-type island positive strains. This is the first description of AbaR-type islands in the CC104 and CC113 that are the most widespread Clonal Complexes in Argentina. In addition, PCR mapping exposed different arrays to those previously described, evidencing the plasticity of this island. Our results evidence a widespread distribution of the AbaR-type genomic islands along the time in the MDRAb population, including the epidemic global clone 1 (GC1) as well as different clonal complexes to those already described in the literature.

Survey of molecular determinants in Gram-positive cocci isolated from hospital settings in Argentina.

BACKGROUND: In order to study the resistance mechanisms to aminoglycosides, tetracyclines and erythromycin, we investigated the genetic determinants on 85 Streptococcus spp., Staphylococcus spp., and Enterococcus spp. isolates collected from 46 hospitals of Argentina over a two-year period. METHODOLOGY: The MICs to amikacin, gentamicin, kanamycin, and streptomycin, tetracycline and erythromycin were determined by the standard broth dilution method according to CLSI recommendations. Detection of resistance genes to the antibiotic tested was assessed by the PCR standard technique whereas the clonal relationships of each species was performed by PFGE. RESULTS: Major heterogeneity was detected in aminoglycoside and erythromycin resistances. Indeed, 37.6% of the isolates harbored the aac(6')-aph(2'') genes; 27% harbored the aph(3')-IIIa and ant(6)-Ia genes along with the aac(6')-aph(2'') gene; 7% carried the ant(4')-Ia gene; and 71% harbored one or more of the erm(A), erm(B), erm(TR), mef(A), mef(E) and msr(A) genes. The tetracycline resistance was determined by the tet(M) gene and was found in 23 isolates that were resistant to this antibiotic. Spreading of tet(M) by the Tn916-like transposon was not a frequent event since the integrase of this element was detected only in 3 Streptococcus spp. isolates. Instead, a 370 bp fragment was detected that corresponded to a region of the CW459-like element integrase in 10 of 11 methicillin-resistant Staphylococcus aureus and in 3 group G Streptococcus isolates, a finding that implies a novel mechanism for tetracycline resistance spreading. CONCLUSION: This study demonstrates the wide spreading of resistance mechanisms in our nosocomial cocci population and underscores the importance of continuous and efficient epidemiological surveillance.

Molecular characterization of methicillin-resistant Staphylococcus aureus isolates reveals the spreading of a new clone in Buenos Aires City.

We performed a hospital-acquired methicillin-resistant Staphylococcus aureus molecular study in Buenos Aires city. Four clones were found harboring the transposable elements Tn4001 and Tn5405 and the erythromycin resistance determinants ermA and mef(E). Of the isolates, 73% belonged to a clone found previously in the city of Córdoba, which showed an epidemic behavior initially attributed to the widely disseminated South American clone.

Molecular characterization of methicillin-resistant staphylococcus aureus isolates reveals the spreading of a new clone in Buenos Aires city

Realizamos un estudio molecular en aislamientos de Staphylococcus aureus adquiridos en el ambiente hospitalario de la ciudad de Buenos Aires. Se hallaron cuatro clones que albergaban los elementos transponibles Tn4001 y Tn5405 y los determinantes de resistencia a eritromicina, ermA y mef(E). El 73% de los aislamientos pertenecían a un clon hallado previamente en la ciudad de Córdoba con características epidemiológicas atribuidas inicialmente al clon sudamericano ampliamente diseminado en el mundo. (AU)

Molecular characterization of methicillin-resistant staphylococcus aureus isolates reveals the spreading of a new clone in Buenos Aires city

Realizamos un estudio molecular en aislamientos de Staphylococcus aureus adquiridos en el ambiente hospitalario de la ciudad de Buenos Aires. Se hallaron cuatro clones que albergaban los elementos transponibles Tn4001 y Tn5405 y los determinantes de resistencia a eritromicina, ermA y mef(E). El 73% de los aislamientos pertenecían a un clon hallado previamente en la ciudad de Córdoba con características epidemiológicas atribuidas inicialmente al clon sudamericano ampliamente diseminado en el mundo. (AU)

Molecular characterization of methicillin-resistant staphylococcus aureus isolates reveals the spreading of a new clone in Buenos Aires city

Realizamos un estudio molecular en aislamientos de Staphylococcus aureus adquiridos en el ambiente hospitalario de la ciudad de Buenos Aires. Se hallaron cuatro clones que albergaban los elementos transponibles Tn4001 y Tn5405 y los determinantes de resistencia a eritromicina, ermA y mef(E). El 73% de los aislamientos pertenecían a un clon hallado previamente en la ciudad de Córdoba con características epidemiológicas atribuidas inicialmente al clon sudamericano ampliamente diseminado en el mundo.

Six-month multicenter study on invasive infections due to Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis in Argentina.

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.

Six-month multicenter study on invasive infections due to group B streptococci in Argentina.

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- micro g kanamycin disks is proposed.