Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in Latin America (Argentina, Chile and Costa Rica): data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

OBJECTIVES: To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015-17 from Argentina, Chile and Costa Rica. METHODS: MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. RESULTS: A total of 170 S. pneumoniae and 218 H. influenzae isolates were collected at five centres in Argentina, Chile and Costa Rica in 2015-17. Small S. pneumoniae isolate numbers from Costa Rica (n = 2) meant that these could only be included in the penicillin susceptibility analysis; they were excluded from further country analyses. Around one-third of pneumococcal isolates from Argentina and two-thirds from Chile were non-susceptible to penicillin by CLSI oral or EUCAST low-dose IV breakpoints, but most (≥89%) were susceptible by CLSI IV or EUCAST high-dose breakpoints. Amongst pneumococci from Argentina, about 80% or more were susceptible to most other antibiotics except cefaclor (all breakpoints), cefixime (PK/PD breakpoints), cefuroxime (EUCAST breakpoints) and trimethoprim/sulfamethoxazole (CLSI and PK/PD breakpoints). S. pneumoniae isolates from Chile showed significantly lower susceptibility (P < 0.05) using CLSI breakpoints compared with those from Argentina for many of the antibiotics tested. Among isolates of H. influenzae from Latin America, more than 90% were susceptible to amoxicillin/clavulanic acid (high dose), cefixime, cefpodoxime, ceftriaxone and fluoroquinolones, irrespective of the breakpoints used. The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified. CONCLUSIONS: Antibiotic susceptibility of H. influenzae isolates was generally high in the Latin American countries studied; however, susceptibility profiles varied for S. pneumoniae by country and depending on the breakpoints used, especially for cefaclor. These factors are important in decision making for empirical therapy of bacterial infections.

Molecular characterization of KPC-2-positive Klebsiella pneumoniae isolates from a neurosurgical centre in Argentina.

Carbapenem-resistant Enterobacteriaceae is a growing concern worldwide. Klebsiella pneumoniae is an important nosocomial pathogen with a high capacity for nosocomial spread. We described the occurrence of plasmid-encoded KPC-2-harbouring K. pneumoniae isolates recovered from a neurosurgical centre in Argentina. The blaKPC-2 gene was surrounded by ISkpn6 and ISkpn7.

Widespread dispersion of the resistance element tet(B)::ISCR2 in XDR Acinetobacter baumannii isolates.

Acinetobacter baumannii is a significant nosocomial pathogen often associated with extreme drug resistance (XDR). In Argentina, isolates of A. baumannii resistant to tetracyclines have accounted for more than 40% of drug-resistant isolates in some hospitals. We have previously reported the dispersion of the tet(B) resistance element associated with the ISCR2 transposase in epidemiologically unrelated A. baumannii isolates recovered from 1983 to 2011. This study extends this surveillance to 77 recent (2009-2013) XDR A. baumannii isolates with different levels of minocycline susceptibility. Isolates were examined by a pan-PCR assay, which showed six different amplification patterns, and specific PCRs were used for the confirmation of the the ΔISCR2-tet(B)-tet(R)-ISCR2 element. The tet(B) gene was present in 66 isolates and the ISCR2 element in 68 isolates; the tet(B) gene was associated with ISCR2 in all tet(B)-positive isolates. We conclude that this element is widespread in XDR A. baumannii isolates from Argentina and could be responsible for the emergence of tetracycline resistance in recent years.

Genetic Variability of AdeRS Two-Component System Associated with Tigecycline Resistance in XDR-Acinetobacter baumannii Isolates.

The emergence of tigecycline resistance has increased in the last years. Although tigecycline-resistant Acinetobacter baumannii isolates were described all over the world, few reports regarding the molecular basis of this resistance are available. It has been recognized that the overexpression of AdeABC efflux pump is related to the tigecycline-resistant phenotype. In 37 clinical A. baumannii isolates we first determined the tigecycline-resistant phenotype and then, within a selected group, we analyzed the sequence of the adeRS operon, which is involved in the expression of the AdeABC efflux pump. Nucleotide sequence analysis of adeR and adeS showed the presence of 5 and 16 alleles, respectively. These results expose a high genetic variability in both genes, the adeS gene being more susceptible to genetic variation. The presence of 2 AdeR and 2 AdeS new variants were reported. Two of the new AdeRS variants were present in the intermediate and the resistant tigecycline A. baumannii isolates, suggesting a putative role in the development of the observed phenotype. More studies need to be addressed to determine the role of the genetic variability observed in the adeRS operon.

Effects of eliminating tension by means of epineural stitches: a comparative electrophysiological and histomorphometrical study using different suture techniques in an animal model / Avaliação dos efeitos da eliminação da tensão através de ancoramento epineural: estudo experimental comparando resultados eletrofisiológicos e histomorfométricos após diferentes técnicas de reparo no nervo

Epineural stitches are a means to avoid tension in a nerve suture. We evaluate this technique, relative to interposed grafts and simple neurorraphy, in a rat model. METHOD: Twenty rats were allocated to four groups. For Group 1, sectioning of the sciatic nerve was performed, a segment 4 mm long discarded, and epineural suture with distal anchoring stitches were placed resulting in slight tension neurorraphy. For Group 2, a simple neurorraphy was performed. For Group 3, a 4 mm long graft was employed and Group 4 served as control. Ninety days after, reoperation, latency of motor action potentials recording and axonal counts were performed. Inter-group comparison was done by means of ANOVA and the non-parametric Kruskal-Wallis test. RESULTS: The mean motor latency for the simple suture (2.27±0.77 ms) was lower than for the other two surgical groups, but lower than among controls (1.69±0.56 ms). Similar values were founding in both group 1 (2.66±0.71 ms) and group 3 (2.64±0.6 ms). When fibers diameters were compared a significant difference was identified between groups 2 and 3 (p=0.048). CONCLUSION: Good results can be obtained when suturing a nerve employ with epineural anchoring stitches. However, more studies are needed before extrapolating results to human nerve sutures.

A aproximação através de pontos epineurais é uma forma de se reduzir a tensão numa neurorrafia. Neste estudo esta técnica é avaliada através da sua comparação com a interposição de enxertos e neurorrafia simples num modelo experimental utilizando o rato. MÉTODO: Vinte ratos foram utilizados e divididos em 4 grupos. No Grupo 1, após a ressecção de 4 mm, os cotos do nervo foram aproximados através de pontos de ancoramento epineurais e suturados com tensão. No Grupo 2, uma neurorrafia simples foi realizada após secção do nervo. No Grupo 3, um enxerto de 4 mm foi utilizado para o reparo e o Grupo 4 foi utilizado como controle. Noventa dias após, os nervos foram novamente expostos e a medida da latência do potencial de ação motor e a contagem axonal foram realizados. A comparação entre os grupos foi realizada através da comparação entre as médias (ANOVA) e com o teste não-paramétrico de Kruskal-Wallis. RESULTADOS: A média da latência motora na sutura simples (2,27±0,77 ms) foi menor em relação aos outros dois grupos onde o nervo foi seccionado e reparado e maior que o grupo controle (1,69±0,56 ms). Resultados semelhantes foram identificados nos grupos 1 (2,66±0,71 ms) e 3 (2,64±0,6 ms). Uma diferença significativa diâmetros das fibras foi identificada quando comparados os grupos 2 e 3 (p=0,048). CONCLUSÃO: Resultados equiparáveis aos obtidos com enxerto podem ser obtidos quando a neurorrafia é realizada com pontos epineurais de ancoramento com tensão, mas estudos adicionais são necessários antes desses resultados serem extrapolados para o reparo de nervo em seres humanos.

Disc coablation and epidural injection of steroids: a comparison of strategies in the treatment of mechanical spinal discogenic pain.

In this study two strategies in the treatment of Mechanical Spinal Discogenic Pain have been compared: Disc Coablation and Epidural Injection of Steroids. In 2003 50 patients treated with one or two epidural injections have been selected "ad random" and 50 patients treated with disc coablation. Comparison of the data indicated an improvement of average VAS when relaxed for both groups (p < 0.01), while after slight-moderate strain, this value was significant only after coablation (p < 0.001). Finally, average VAS was clearly lower (p < 0.01) after coablation as compared to epidural injections.