Is it possible to perform bacterial identification and antimicrobial susceptibility testing with a positive blood culture bottle for quick diagnosis of bloodstream infections?

Abstract INTRODUCTION: Bloodstream infections can be fatal, and timely identification of the etiologic agent is important for treatment. METHODOLOGY: An alternative method, consisting of direct identification and susceptibility testing of blood culture bottles using the automated VITEK 2® system, was assessed. RESULTS: All 37 of the Gram-negative bacilli (GNB) identifications and 57.1% of the 28 Gram-positive cocci (GPC) identifications matched those obtained with standard methods. In susceptibility testing, the agreement was greater than 90%. CONCLUSIONS: This alternative methodology may assist in the early identification and susceptibility testing of GNB. Further research is necessary to develop appropriate methods for GPC.

Evaluation of MicroScan and Phoenix System for Rapid Identification and Susceptibility Testing Using Direct Inoculation from Positive BACTEC Blood Culture Bottles / 대한진단검사의학회지

BACKGROUND: Procedures for rapid identification and susceptibility testing by direct inoculation (DI) from positive blood culture bottles into an automated system have not been standardized. This study was purposed to evaluate DI from BACTEC 9240 blood culture system (BD, USA) into MicroScan (Dade Behring, USA) or Phoenix (BD, USA). METHODS: From May to June 2006, bacterial pellets from positive aerobic bottles showing gram-positive cocci (GPC) or gram-negative rods (GNR) of single morphology were directly inoculated to MicroScan PosCombo1A and NegCombo32 and to Phoenix PMIC/ID-107 and NMIC/ID-53. In addition, the automated instruments were also inoculated from subcultures (standard inoculations, SI). Species identification and susceptibilities were compared between DI and SI and between MicroScan and Phoenix. RESULTS: A total of 108, 104, and 78 specimens were tested with MicroScan, Phoenix, and both, respectively. When DI and SI were matched, 94.8% of GPC were correctly identified with MicroScan, compared to 80.7% with Phoenix, and 93.9% of GNR were correctly identified with MicroScan, compared to 95.7% with Phoenix. DI with MicroScan and Phoenix showed correct susceptibilities in 94.6% of 1,150 and 96.5% of 660 tests (with very major error [VME] of 1.1% and 1.1%), respectively, among GPC and in 94.4% of 942 and 96.3% of 781 tests (with VME of 0.6% and 0%), respectively, of GNR. Correlation of identification/susceptibilities between MicroScan and Phoenix using DI were 81.8%/98.0% for Staphylococcus aureus and 100.0%/95.6% for Escherichia coli. CONCLUSIONS: DI warrants a reliable method for identification and susceptibility testing of both GPC and GNR in MicroScan, and those of only GNR in Phoenix.

The recent evolution of therapeutic weapons against resistant Gram-positive microorganisms

Multiresistant Gram-positive cocci, including Staphylococcus aureus, the group of coagulase-negative staphylococci, Enterococcus faecalis and Enterococcus faecium, as well as Streptococcus pneumoniae and other streptococci, represent emerging pathogens. This issue is especially concerning in the setting of immunocompromised, hospitalized patients, in particular when surgery, invasive procedures, or prosthetic implants are carried out, patients are admitted in intensive care units, or underlying chronic disorders and immunodeficiency are of concern, and broad-spectrum antibiotics are widely used in the environment; moreover, a community spread of resistant Gram-positive cocci has been recognized during recent years. The spectrum of antimicrobials available for an effective management of these relevant infections is significantly threatened by the emerging of methicillin-resistant and more recently glycopeptide-resistant strains. The streptogramine association represented by quinupristin/dalfopristin, the oxazolidinone derivative linezolid, and the recently licensed daptomycin and tigecycline, together with a number of glycopeptides, fluoroquinolones, cephalosporins, and other experimental compounds, represent an effective response. It is due to the innovative mechanisms of action of these compounds, their maintained or enhanced activity against multiresistant pathogens, their effective pharmacokinetic/pharmacodynamic properties, their frequent possibility of synergistic activity with other compounds effective against Gram-positive pathogens, and a diffuse potential for a safe and easy administration, also to compromised patients.

Evolución de la resistencia a ciprofloxacina y otras quinolonas en bacterias clínicamente significantes / Evolution of resistance to ciprofloxacine and other quinolones in clinically significant bacteria

La incidencia de resistencia a las fluoroquinolonas se ha incrementado drásticamente en los últimos años, presentándose en todas las especies bacterianas. Dicha resitencia se ha descrito, principalmente, en aislamientos nosocomiales; sin embargo, reportes recientes a nivel mundial, describen resistencia entre bacterias responsables de infecciones adquiridas en la comunidad. Por su amplio espectro de actividad, la ciprofloxacina (CIP) es la quinolona más ampliamente utilizada y su sensibilidad o resistencia se determinó a 2.540 cepas entre enterobacterias, bacilos Gram negativos no fermentadores de la glucosa y cocos Gram positivos, distribuidos como sigue: E.coli (703), K.pneumoniae (358), E.cloacae (130), P.mirabilis (121), M.morganii (43), E.Agglomerans (40), E.aerogenes (27), C.freundii (18), C.diversus (14), S.marcescens (8), otras especies de enterobacterias (29), Ps.aeruginosa (311), Acinetobacter genoespecies oxidativas (107), Acinetobacter genoespecies inactivas (75), S.aureus (439), Enterococcus sp. (54) y Staphylococcus coagulasa negativa (SCN) (63). Estas cepas bacterianas fueron recolectadas consecutivamente entre los años 1992-1997 de pacientes ambulatorios. Se utilizó el método de difusión en agar para determinar los patrones de suceptibilidad a CIP. A 468 aislamientos obtenidos de urocultivos, se les determinó, además, la suceptibilidad al ácido nalidíxico (AcN), cinoxacina (CIN) y norfloxacina (NOR). La resistencia obtenida para cada bacteria es la siguiente: E.coli: CIP (11 por ciento), CIN (11 por ciento), NOR (10 por ciento) y AcN (15 por ciento), K.pneumoniae CIP (7 por ciento), CIN (14 por ciento), NOR (13 por ciento) y AcN (20 por ciento); E.cloacae CIP (2 por ciento), CIN (23 por ciento), NOR (23 por ciento) y AcN (23 por ciento), M.morganii CIP (19 por ciento), E.aerogenes CIP (7 por ciento), P.mirabilis CIN (2 por ciento) y AcN (10 por ciento), Ps.aeruginosa CIP (5 por ciento), Acinetobacter genospecies oxidativas CIP (36 por ciento), Acinetobacter genoespecies inactivas CIP (5 por ciento) S.aureus CIP (1 por ciento), SCN: CIP (2 por ciento) y Enterococcus sp. CIP (13 por ciento). No se encontró resistencia a CIP en el resto de las especies de enterobacteria. En conclusión, la presencia de bajos porcentajes de resistencia a CIP en la mayoría de las cepas aisladas de pacientes que presentan infecciones adquiridas en la comunidad, permiten que este antimicrobiano pueda seguir siendo utilizado

Sinusitis aguda en niños tratamiento con azitromicina esquema de tres días / Acute sinusitis in children a three-day scheme azitromycin treatment

Se realizó un estudio abierto comparativo multicéntrico, en el que participaron 51 niños en edades comprendidas entre 1 y 10 años de edad, los cuales tenían diagnóstico clínico y radiológico de sinusitis aguda, con la finalidad de evaluar la eficacia y tolerancia de un régimen de azitromicina (10 mg/kg/día) durante tres días. De los 51 pacientes incluidos, 27 pacientes tenían sinusitis máxilo etmoidal (52,9 por ciento), 10 maxilar unilateral (19,6 por ciento), 9 maxilar bilateral (17,6 por ciento) y 5 niños presentaban compromiso de seno etmoidal (9,8 por ciento), no se evidenció afectación de senos frontales. Los pacientes fueron evaluados durante el estudio entre el tercero-quinto día y entre el décimo cuarto día; 6 pacientes no acudieron a la primera visita postratamiento. En la segunda visita 46 pacientes (90 por ciento) se curaron; 2 pacientes (4 por ciento) tuvieron mejoría y 3 pacientes (6 por ciento) presentaron recaída clínica, en este último grupo habían factores predisponentes para recurrencia (atopia, hipertrofia adenoidea, déficit de IgA). Entre los efectos adversos 2 pacientes reportaron epigastralgia leve (3,9 por ciento). En conclusión 94 por ciento de los pacientes evaluados tuvieron evolución satisfactoria por lo que consideramos que la azitromicina por vía oral, en régimen de tres días, resulta segura para el tratamiento de niños con sinusitis aguda, debido a su eficacia terapéutica, cómoda posología y escasos efectos adversos