Polymyxin-Resistant Acinetobacter spp. Isolates: What is Next?

Univ Fed Sao Paulo, Div Infect Dis, Lab Especial Microbiol Clin, BR-04025010 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Div Infect Dis, Lab Especial Microbiol Clin, BR-04025010 Sao Paulo, SP, BrazilWeb of Scienc

Antimicrobial activity of dalbavancin tested against Gram-positive clinical isolates from Latin American medical centres

The activity of dalbavancin, a new semi-synthetic lipoglycopeptide antibiotic, was evaluated in comparison with other antibacterial agents against 1229 Gram-positive organisms collected from medical centres in Latin America. Dalbavancin was the most potent compound tested against isolates of Staphylococcus aureus (MIC50, 0.06 mg/L) and coagulase-negative staphylococci (MIC50, 0.03 mg/L), independently of methicillin susceptibility. Dalbavancin inhibited all Streptococcus pneumoniae isolates at less than or equal to 0.06 mg/L. Dalbavancin also demonstrated excellent activity against beta-haemolytic (MIC50, less than or equal to 0.008 mg/L) and viridans group (MIC50, 0.016 mg/L) streptococci. All vancomycin-susceptible Enterococcus spp. isolates were inhibited by dalbavancin at less than or equal to 0.25 mg/L, but some vancomycin-resistant Enterococcus spp. isolates were only inhibited by dalbavancin levels of greater than or equal to 8 mg/L. Dalbavancin exhibited excellent activity against isolates of Corynebacterium spp. and Listeria spp. Dalbavancin may provide an important therapeutic option for Gram-positive infections, excluding those caused by enterococci with VanA-type resistance.Universidade Federal de São Paulo, Div Infect Dis, São Paulo, BrazilJONES Grp, JMI Labs, N Liberty, IA USATufts Univ, Sch Med, Boston, MA 02111 USAUniversidade Federal de São Paulo, Div Infect Dis, São Paulo, BrazilWeb of Scienc

Global assessment of the antimicrobial activity of polymyxin B against 54 731 clinical isolates of Gram-negative bacilli: report from the SENTRY antimicrobial surveillance programme (2001-2004)

In total, 54 731 Gram-negative bacilli isolated worldwide between 2001 and 2004 from diverse sites of infection were tested for susceptibility to polymyxin B by the broth reference microdilution method, with interpretation of results according to CLSI (formerly NCCLS) guidelines. Polymyxin B showed excellent potency and spectrum against 8705 Pseudomonas aeruginosa and 2621 Acinetobacter spp. isolates (MIC50, 98% susceptible) against Citrobacter spp., Escherichia coli and Klebsiella spp., but activity was more variable against Enterobacter spp. (MIC50, 8 mg/L) against Burkholderia cepacia (11.8% susceptible), Serratia spp. (5.4% susceptible), indole-positive Proteus spp. (1.3% susceptible) and Proteus mirabilis (0.7% susceptible).Universidade Federal de São Paulo, Div Infect Dis, BR-04025010 São Paulo, BrazilJMI Labs, N Liberty, IA USATufts Univ, Sch Med, Boston, MA 02111 USAUniversidade Federal de São Paulo, Div Infect Dis, BR-04025010 São Paulo, BrazilWeb of Scienc

Avaliação da técnica de MALDI-TOF MS no laboratório de microbiologia

Rapid identification of microorganisms by the clinical microbiology laboratory is of crucial importance for optimal patients’ management and treatment. In general, bacterial identification by conventional methods requires 18-24 hours for colony isolation and at least 24 additional hours for species identification. New technologies in microbiology have focused on the rapid diagnosis of bloodstream infections, since they are associated with high morbidity and mortality rates.A rápida identificação de microrganismos no laboratório de microbiologia clínica é de extrema importância para direcionar o manejo e o tratamento de pacientes. Geralmente, a identificação bacteriana por métodos bioquímicos convencionais necessita de 18 a 24 horas para o crescimento e o isolamento da colônia bacteriana e, pelo menos, 24 horas adicionais para a identificação da espécie. Novas tecnologias em microbiologia têm focado no desenvolvimento de métodos relacionados com o diagnóstico rápido das infecções da corrente sanguínea, uma vez que essas infecções são associadas à alta morbimortalidade.UNIFESPUNIFESP Infectious Disease Department ALERTA laboratoryNational Council for Scientific and Technological DevelopmentBrazilian Society of Infectious Diseases Bacteriology CommitteeUNIFESP, Infectious Disease Department ALERTA laboratorySciEL

Comparative antimicrobial activity between meropenem and imipenem/cilastatina: does the clinical laboratory need to test both imipenem and meropenem routinely?

Meropenem and imipenem are the most active and potent ß-lactams against gram-negative bacteria and the only carbapenems commercially available in Brazil, USA, and Europe. Meropenem has higher in vitro activity against gram-negative bacteria, while imipenem has slightly higher in vitro activity against gram-positive. The objectives of this study are to compare the in vitro activities of these carbapenems and to evaluate the necessity of susceptibility testing both compounds at the routine of the microbiology laboratory. The broth microdilution results of 2,144 gram-negative bacilli were analyzed. Against Enterobacteriaceae meropenem was at least eight-fold more potent than imipenem. Against Pseudomonas aeruginosa meropenem (MIC50, 1mug/ml) was also more potent than imipenem (MIC50, 2mug/ml), and against Acinetobacter baumannii both carbapenems presented similar in vitro activities (MIC50, 1mug/ml for both). Only 2.7% of the isolates presented discrepant category results between the carbapenems; i.e. susceptible to one and resistant to the other. Forty-six isolates (2.14%) were susceptible to meropenem and resistant to imipenem; while only 12 isolates (0.55%) were susceptible to imipenem and resistant to meropenem. The vast majority of discordant results (91.4%) occur among non-fermentative bacilli (NF-BGN). Five discordant results were detected among 1,350 Enterobacteriaceae evaluated (0.37%); while 53 discrepant results were detected among 794 NF-BGN (6.64%). Isolates showing susceptibility to meropenem and resistance to imipenem account for 80% of the discrepant results. The results of this study indicate that the microbiology laboratory may susceptibility test only one of the carbapenems for Enterobacteriaceae and use the same category result for the other one. It is important that the results for both carbapenems are sent to the physicians in order for them to be able to choose the most appropriated for the case. On the other hand, for NF-BGN the laboratory should susceptibility test both carbapenems.O meropenem e o imipenem representam os ß-lactâmicos com maior espectro e potência antimicrobiana, e são os únicos carbapenêmicos disponíveis para uso clínico no Brasil, nos Estados Unidos e na Europa. O meropenem apresenta atividade in vitro superior contra gram-negativos, enquanto que o imipenem é discretamente mais ativo contra gram-positivos. Os objetivos deste estudo são comparar as atividades in vitro destes dois carbapenêmicos e avaliar a necessidade de o laboratório clínico testá-los em sua rotina. Os resultados da avaliação dos padrões de sensibilidade de 2.144 bacilos gram-negativos pela técnica de microdiluição em caldo foram analisados. Contra enterobactérias, o meropenem apresentou atividade pelo menos oito vezes maior que o imipenem. Contra Pseudomonas aeruginosa, o meropenem (CIM50 de 1mig/ml) também apresentou atividade superior à do imipenem (CIM50 de 2mig/ml), e contra Acinetobacter baumannii, a ação dos dois é equivalente (CIM50 de 1mig/ml para ambos). Somente 2,7% das amostras avaliadas apresentaram resultados discordantes entre os dois carbapenêmicos em termos de categoria de sensibilidade - isto é, foram sensíveis a um e resistentes ao outro. Quarenta e seis amostras (2,14%) foram sensíveis ao meropenem e resistentes ao imipenem, enquanto que somente 12 amostras (0,55%) apresentaram sensibilidade ao imipenem e resistência ao meropenem. A grande maioria dos resultados discordantes (91,4%) ocorreu entre as amostras de bacilos gram-negativos não-fermentadores da glicose (BGN-NF). Entre as 1.350 enterobactérias testadas houve apenas cinco resultados discordantes (0,37%), enquanto que entre os BGN-NF ocorreram 53 (6,67%). Além disso, em cerca de 80%, as amostras foram sensíveis ao meropenem e resistentes ao imipenem. Os resultados deste estudo indicam que o laboratório de microbiologia pode testar apenas um dos carbapenêmicos contra enterobactérias, considerando para o outro o mesmo resultado. É importante que os resultados dos dois carbapenêmicos sejam colocados no relatório, para que o médico possa escolher aquele que achar mais adequado. Por outro lado, para os BGN-NF, o laboratório deve realizar o teste de sensibilidade com os dois carbapenêmicos separadamente.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

Antimicrobial susceptibility patterns of unusual nonfermentative gram-negative bacilli isolated from Latin America: report from the SENTRY Antimicrobial Surveillance Program (1997-2002)

The antimicrobial susceptibility of 176 unusual non-fermentative gram-negative bacilli (NF-GNB) collected from Latin America region through the SENTRY Program between 1997 and 2002 was evaluated by broth microdilution according to the National Committee for Clinical Laboratory Standards (NCCLS) recommendations. Nearly 74% of the NF-BGN belonged to the following genera/species: Burkholderia spp. (83), Achromobacter spp. (25), Ralstonia pickettii (16), Alcaligenes spp. (12), and Cryseobacterium spp. (12). Generally, trimethoprim/sulfamethoxazole (MIC50, 16 µg/ml; 18.8% susceptible) and meropenem (MIC50, 8 µg/ml; 50% susceptible) against Ralstonia pickettii. Since selection of the most appropriate antimicrobial agents for testing and reporting has not been established by the NCCLS for many of NF-GNB species, results from large multicenter studies may help to guide the best empiric therapy.Universidade Federal de São Paulo (UNIFESP) Departamento de MedicinaJMI Laboratories The Jones GroupUNIFESP, Depto. de MedicinaSciEL