Colonization pressure as a risk factor for colonization by multiresistant Acinetobacter spp and carbapenem-resistant Pseudomonas aeruginosa in an intensive care unit

OBJECTIVE: To determine factors associated with colonization by carbapenem-resistant Pseudomonas aeruginosa and multiresistant Acinetobacter spp. METHODS: Surveillance cultures were collected from patients admitted to the intensive care unit at admission, on the third day after admission and weekly until discharge. The outcome was colonization by these pathogens. Two interventions were implemented: education and the introduction of alcohol rubs. Compliance with hand hygiene, colonization pressure, colonization at admission and risk factors for colonization were evaluated. RESULTS: The probability of becoming colonized increased during the study. The incidence density of colonization by carbapenem-resistant P. aeruginosa and multiresistant Acinetobacter spp. and colonization pressure were different between periods, increasing gradually throughout the study. The increase in colonization pressure was due to patients already colonized at admission. The APACHE II score, colonization pressure in the week before the outcome and male gender were independent risk factors for colonization. Every 1% increase in colonization pressure led to a 2% increase in the risk of being colonized. CONCLUSION: Colonization pressure is a risk factor for carbapenem-resistant P. aeruginosa and multiresistant Acinetobacter spp. colonization. When this pressure reaches critical levels, efforts primarily aimed at hand hygiene may not be sufficient to prevent transmission. .

Ceftriaxone and ciprofloxacin restriction in an intensive care unit: less incidence of Acinetobacter spp. and improved susceptibility of Pseudomonas aeruginosa / Restricción del uso de ceftriaxona y ciprofloxacino en una unidad de cuidados intensivos: menor incidencia de Acinetobacter spp. y mayor sensibilidad de Pseudomonas aeruginosa

Objective. To determine whether restricting the use of ceftriaxone and ciprofloxacin could significantly reduce colonization and infection with resistant Gram-negative bacilli (r-GNB). Methods. A two-phase prospective study (before/after design) was conducted in an intensive care unit in two time periods (2004–2006). During phase 1, there was no antibiotic restriction. During phase 2, use of ceftriaxone or ciprofloxacin was restricted. Results. A total of 200 patients were prospectively evaluated. In phase 2, the use of ceftriaxone was reduced by 93.6% (P = 0.0001) and that of ciprofloxacin by 65.1% (P = 0.041), accompanied by a 113.8% increase in use of ampicillin-sulbactam (P = 0.002). During phase 1, 48 GNB were isolated [37 r-GNB (77.1%) and 11 non-r-GNB (22.9%)], compared with a total of 64 during phase 2 [27 r-GNB (42.2%) and 37 non-r-GNB (57.8%)] (P = 0.0002). Acinetobacter spp. was isolated 13 times during phase 1 and 3 times in phase 2 (P = 0.0018). The susceptibility of Pseudomonas aeruginosa to ciprofloxacin increased from 40.0% in phase 1 to 100.0% in phase 2 (P = 0.0108). Conclusions. Restriction of ceftriaxone and ciprofloxacin reduced colonization byAcinetobacter spp. and improved the susceptibility profile of P. aeruginosa.

Objetivo. Determinar si la restricción del uso de ceftriaxona y ciprofloxacino reduce significativamente la colonización y la infección por bacilos gramnegativos resistentes. Métodos. Se efectuó un estudio prospectivo de dos fases (diseño antes/después de la intervención) en una unidad de cuidados intensivos en dos períodos sucesivos entre los años 2004 y 2006. Durante la fase 1, no hubo ninguna restricción de antibióticos. Durante la fase 2, se restringió el uso de ceftriaxona y ciprofloxacino. Resultados. Se evaluó prospectivamente a 200 pacientes en total. En la fase 2, el uso de ceftriaxona se redujo en 93,6% (P = 0,0001) y el de ciprofloxacino en 65,1% (P = 0,041), lo que se acompañó de un aumento de 113,8% en el uso de ampicilina/sulbactam (P = 0,002). Durante la fase 1, se aislaron 48 bacilos gramnegativos (37 resistentes [77,1%] y 11 no resistentes [22,9%]), en comparación con un total de 64 durante la fase 2 (27 resistentes [42,2%] y 37 no resistentes [57,8%]) (P = 0,0002). Se aisló Acinetobacter spp. 13 veces durante la fase 1 y 3 veces en la fase 2 (P = 0,0018). La sensibilidad de Pseudomonas aeruginosa al ciprofloxacino aumentó de 40,0% en la fase 1 a 100,0% en la fase 2 (P = 0,0108). Conclusiones. La restricción del uso de ceftriaxona y ciprofloxacino redujo la colonización por Acinetobacter spp. y mejoró el perfil de sensibilidad de P. aeruginosa.

Identifying and controlling a multiresistant pseudomonas aeruginosa outbreak in a latin-american cancer centre and its associated risk factors

Pseudomonas aeruginosa is an important and frightening microorganism for patients suffering from cancer. Multiresistant P. aeruginosa (MRPA) may appear as a consequence of exposure to multiple antibiotics or from a breakdown in infection control practices. This article reports an MRPA outbreak in a cancer treatment centre and the consequent case control study. Mechanical ventilation was identified as being the main risk factor for developing MRPA colonisation or infection; molecular analysis confirmed the outbreak. A multifaceted strategy was adopted, involving reinforcing hand-washing practices, contact isolation, antibiotic restriction and suction devices for mechanically-ventilated patients. MRPA was controlled and the outbreak ended. Such strategy may be effective in controlling MRPS in low-resource environments amongst high risk cancer patients.

Prevalência de Pseudomonas aeruginosa produtoras de β lactamases do tipo AMP-C em isolados clínicos de Santa Maria - RS / Prevalence of Pseudomonas aeruginosa AMP-C β lactamases in clinical isolates of Santa Maria - RS

Microbiologia proporcionar informações claras ao clínico, reportando corretamente os resultados, para que o tratamento seja eficaz e o mais seguro possível, evitando-se assim, a falha terapêutica e a resistência microbiana. As β-lactamases são enzimas que catalizam a hidrólise de ligações carbono-nitrogênio, separando a base do substrato inativando os antimicrobianos β-lactâmicos acarretando em falha terapêutica. Neste trabalho analisou-se 90 amostras de Pseudomonas aeruginosa provenientes de isolados clínicos de Santa Maria-RS. Empregou-se a técnica de disco difusão (Kirby-Bauer), com aproximação dos discos de Cefoxitina e Cefotaxima, onde31 cepas (34,4%) apresentaram positividade in vitro para a produção deβ-lactamases do tipo Amp-C. As cepas do grupo CESP (Citrobacter freundii, Enterobacter sp., Providencia sp., Serratia marcescens) apresentam resistência à Cefoxitina no antibiograma e não necessitariam de testes especiais para a detecção, uma vez que a enzima é produzida de forma constitutiva. Porém, alguns isolados de Pseudomonas aeruginosa, devido à produção de Amp-C em pequenas quantidades, podem apresentar sensibilidade in vitro à Cefoxitina, mas in vivo este antimicrobiano não terá ação ou sua ação será reduzida, ocasionando falha terapêutica.

[Evaluation of efficacy of the current disinfectants on staphylococcus epidermidis and pseudomonas aeroginosa isolated from hospitals of Hamadan in 2006]

Choosing the effective disinfectants and using the standard methods of sterilization in hospitals, can be useful in decreasing nosocomial infections. The aims of this study were the evaluation of efficacy of disinfectants being used in surgical rooms, ICU, CCU, burn wards and delivery rooms of Hamedan hospitals and also determination of bacterial contamination. In this study 400 samples were collected from different parts of operation rooms, ICU, CCU and delivery rooms of four hospitals [Mobasher Kashani, Imam Khomainy, Ekbatan and Fatemieh] in 2006. The samples were cultured on blood agar, then the microbial agents were identified by differential and biochemical tests. Disinfectants that were used were as follow: Cidex [Glutaraldeyde], Sodium hypochlorite, Kereoeline 2.5%, Hygiene 1%, Betadine, Alcohol 70%, Savlone 3.2%, Chlorohexidine 1%. The efficacy of disinfectants was evaluated on 60 Staphylococcus epidermidis and 60 Pseudomonas aeroginosa through disk diffusion method. Data were gathered through a questionnaire and analysed using T-test and SPSS software. Contamination tests in the four hospital were positive in 44.5% of cultures [178 cultures]. The highest frequency of contamination was in Mobasher hospital with 38.2% and the less frequency was in Fatemieh hospital with 13.5%. From 400 samples, 52.2% of isolates were gram-positive bacteria and 47.7% were gram-negative bacteria. The most important bacteria isolated were as follow: E.coli, Staphylococcus epidemidis, Micrococci, Bacillus subtili and Pseudomonas aeroginosa. The most effective disinfectants on 60 Staphylococcus epidemidis were as follow: Cidex, Sodium Hypochlorite and Kereoeline and the least effective disinfectants and antiseptics was Alcohol 70%. The most effective disinfectants on 60 Pseudomonas aeroginosa were as follow: Cidex and Kereoeline and the least effective disinfectants and antiseptics were Alcohol 70% and Savlone. Results showed that kereoline and cidex were among the most effective disinfectants, and there is not a significant difference between their effects on staphylococcus epidermidis [P=0.469] and on pseudomonas aeroginosa [P=0.053]. The efficacy of other disinfectants on two mentioned bacteria were different and significant differences were found

Influencia de la materia orgánica sobre la acción de desinfectantes / Organic material influence on the desinfectants action

En la práctica de la desinfección, el antagonismo existente entre material orgánico y los desinfectantes, dio lugar a un estudio tendiente a determinar el grado de tolerancia que pueden presentar estos compuestos frente a diferentes concentraciones de sustancia orgánica. Dicho estudio se llevó a cabo con veinte soluciones de desinfectantes normalmente utilizados en el área hospitalaria, determinándose su actividad sobre los microorganismos habitualmente contaminantes o infectantes. Como microorganismos de ensayo se utilizaron: Escherichia coli, Staphylococcus aureus y Pseudomonas aeruginosa. La sustancia orgánica antagonista, constituida por una mezcla de suero equino con levadura de cerveza, se usó en concentraciones finales del 5, 10, 15 y 20 por ciento. Los resultados permiten considerar un comportamiento variable en el grado de antagonismo en dos aspectos: 1) con los diferentes compuestos y, 2) con las diferentes especies microbianas utilizadas. Con respecto al primero, se demostró que algunos compuestos no fueron inhibidos por una elevada concentración de sustancias orgánicas (20 por ciento), tal como el hipoclorito de sodio con 6000 mg por litro de cloro activo. Sin embargo, no todos los desinfectantes considerados de alto nivel alcanzaron esa barrera, tal el caso del glutaraldehido y del formaldehido que en las concentraciones utilizadas del 1 por ciento al 8 por ciento respectivamente, fueron inhibidos por esa concentración de sustancia orgánica. En el segundo aspecto, se observó que en presencia de material orgánico, tanto Staphylococcus aureus como Pseudomonas aeruginosa, mostraron mayor resistencia a los desinfectantes que Escherichia coli. Los resultados obtenidos permiten concluir que, entre los criterios de selección de un desinfectante, debe asignarse un rol primordial al contenido de materia orgánica en los elementos a desinfectar. De esta forma, se incrementará la probabilidad de procedimientos exitosos