Mécanismes de résistance de Pseudomonas aeruginosa

Date du colloque&nbsp;: 01/2009</p

Nosocomial and community-acquired Acinetobacter infections

Members of the genus Acinetobacter are involved in a wide spectrum of infections. Although this organism is mainly associated with nosocomial infections, these bacteria have been recently shown involved in community-acquired infection. Over 1,000 published papers refer to “infections by antibiotic resistant acinetobacter in the international literature.” This opportunistic commensal bacterium was initially considered a relatively low-grade pathogen and frequently ignored until the 1960s, even when isolated from clinical samples. However, marked improvement in culture techniques in the last 30 years increased awareness of infections due to acinetobacter. Prior to the 1970s, nosocomial infections by this organism were mainly detected after surgical procedures or in the urinary tract from patients hospitalized in intensive care units (ICU), but since the 1980s, acinetobacters were found rapidly spread among ICU patients. At the present time, this bacterium represents about 9–10% of all nosocomial infections, but the majority are due to respiratory tract infection. The origin of such infections is known to be both endogenous and exogenous, and the introduction of single-use disposable patient items is now known to limit endogenous infection. Nevertheless, transmission of the bacteria by the hands of hospital staff is now known to be an important risk factor for patient colonization. Of the many different microbial species isolated from various environments, Acinetobacter baumannii is known to be the most frequently involved in human infections. Although the reservoirs outside of hospital environments are not clearly defined, community acquired infection and infection related to war or earthquakes have been recognized and may be due to presence of these microbes in the soil. The severity of such infection by this bacterium depends on the site of infection and the degree of a patient’s immune competence related to underlying disease. Acinetobacter may cause mild to severe illness and can be fatal. However, a consensus whether this organism is indeed highly pathogenic is not established since this organism is thought to be mainly a low-grade pathogen. It is likely that increased pathogenesis by this microbe involves numerous factors, including virulence factors that are not yet clear. However, there is now increased interest in this pathogen the last 30 years (Livermore, 2003), since recognition of antibiotic multiresistant strains, including pan resistance, emerged in an outbreak in a clinical unit (Del Mar et al., 2005; Fierobe et al., 2001; Mah et al., 2001; Rello, 2003; Simor et al., 2002; Smolyakov et al., 2003). In hot and humid areas such as the tropics, acinetobacter infections are usually community acquired, in general bacteremias, or primary infections (Anstey et al., 2002)

Infections émergentes à Acinetobacter baumannii et circonstances favorisant leur survenue

During the last decade, Acinetobacter baumannii (AB) has been increasingly responsible for infections occurring in three particular contexts (in terms of patients and environment). Community AB pneumonia is severe infections, mainly described around the Indian Ocean, and which mainly concern patients with major co-morbidities. AB is also responsible for infections occurring among soldiers wounded in action during operations conducted in Iraq or Afghanistan. Lastly, this bacterium is responsible for infections occurring among casualties from natural disasters like earthquakes and tsunamis. Those infections are often due to multidrug-resistant strains, which can be implicated in nosocomial outbreaks when patients are hospitalized in a local casualty department or during their repatriation thereafter. The source of the contaminations which lead to AB infections following injuries (warfare or natural disasters) is still poorly known. Three hypotheses are usually considered: a contamination of wounds with environmental bacteria, a wound contamination from a previous cutaneous or oropharyngeal endogenous reservoir, or hospital acquisition. The implication of telluric or agricultural primary reservoirs in human AB infections is a common hypothesis which remains to be demonstrated by further specifically designed studies

Methicillin-resistant Staphylococcus aureus (MRSA) in the institutionalized older patient

SummaryNursing homes and long-term care facilities are usually considered as reservoirs for methicillin-resistant Staphylococcus aureus (MRSA) carriers. Actually, there are major differences in MRSA carriage between institutions, with variations from 1% to more than 30%. Overall there is a low incidence of MRSA infection in these institutions, even though carriage is associated with a higher risk of subsequent MRSA infection, with high mortality rates. The main risk factors for carriage are well known: recent hospitalization in an acute-care ward, skin wounds and recent antimicrobial therapy. Age over 75 years is also a risk factor. Residents of nursing homes and long-term care facilities pose a risk of MRSA transfer to acute-care wards, with potential consequences in terms of infection control strategy or surgical antibiotic prophylaxis. No well-designed study has identified the best strategy for MRSA control in institutions for older people and strategies that have been proposed are controversial. Studies to elucidate this would be useful, as well as studies specifically designed to identify the relative importance of different ways of MRSA transmission in these institutions (cross-transmission via healthcare workers or the environment, or direct transmission from one resident to another). Finally, a first important step towards MRSA control is a strict application of standard precautions, particularly good compliance with hand hygiene

Virulence and pathogenesis. Acinetobacter Infections: Microbiological, Clinical and Therapeutical Aspects

Date du colloque&nbsp;: 09/2009</p

Correlation between glove use practices and compliance with hand hygiene in a multicenter study with elderly patients

In a study conducted in 11 health care settings for elderly patients, we demonstrated a significant negative correlation between the proportion of glove use outside any risk of exposure to body fluids and compliance with hand hygiene (P &lt; .02). This result underscores a major limitation of strategies for controlling the spread of multidrug-resistant bacteria that recommend systematic glove use for each contact with carriers or their environment

Infection urinaire à Haemophilus influenzae chez 3 enfants ayant une malformation de l’arbre urinaire

La pyélonéphrite aigue (PNA) est une des infections les plus fréquentes de l’enfant, dans laquelle le genre Haemophilus est très rarement impliqué. De janvier 2010 à octobre 2011, seulement 3 enfants âgés de moins de 15 ans ont été hospitalisés dans notre établissement pour une infection urinaire à Haemophilus influenzae. Les 3 enfants présentaient des tableaux typiques de PNA : fièvre, signes fonctionnels urinaires ou douleurs abdominales. L’examen cytobactériologique des urines (ECBU) montrait à l’examen direct une leucocyturie significative et de nombreux bacilles Gram négatifs. La culture bactériologique standard des urines des 3 patients était négative. H. influenzae a été mis en évidence secondairement après réensemencement des urines sur milieu enrichi. Les 3 enfants présentaient une uropathie : 2 syndromes de la jonction pyélo-urétérale droit et une duplicité urétérale bilatérale avec reflux de haut grade. Pendant la période étudiée, la prévalence des PNA à Haemophilus dans notre établissement a été de 0,02 % dans les infections urinaires de l’enfant. Dans la littérature, les PNA à Haemophilus sont rares (moins de 1 % chez l’enfant), fréquemment associées à une malformation de l’arbre urinaire et difficiles à mettre en évidence. Lorsque l’ECBU montre des bacilles Gram négatifs à l’examen direct non retrouvés à la culture, il faut réensemencer les urines sur gélose au sang cuit, notamment si le patient est porteur d’une uropathie

Colistin, rifampicin, and meropenem administered as single agents in a model of pneumonia caused by a carbapenem-resistant Acinetobacter baumannii

International audienc