NosoVeille n°11 Novembre 2009 Rédacteurs : Nathalie Sanlaville

NosoVeille n°11
Novembre 2009
Rédacteurs : Nathalie Sanlaville, Sandrine Yvars, Annie Treyve
Ce bulletin de veille est une publication mensuelle qui recueille les publications
scientifiques publiées au cours du mois écoulé.
La recherche documentaire est effectuée dans la base de données
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Abonnement / Désabonnement
Sommaire de ce numéro
Acinetobacter
Antibiotique
Bactériémie
Chirurgie
Environnement
Grippe
Hémodialyse
Hépatite C
Hygiène des mains
Pédiatrie
Personnel
Pneumonie
Réanimation
Staphylococcus aureus
Surveillance

Acinetobacter
NosoBase n° 25717
Epidémie d'infections à Acinetobacter baumannii multirésistant aux antibiotiques dans une unité de
réanimation polyvalente : analyse clinique, épidémiologique et évolution du profil PFGE
Monterrubio-Villar J; Gonzalez-Velasco C; Valdezate-Ramos S; Cordoba-Lopez A; Villalon-Panzano P;
Saez-Nieto JA. Outbreak of multiresistant Acinetobacter baumannii in a polyvalent intensive care unit:
clinical, epidemiological analysis and PFGE-printing evolution. European journal of clinical microbiology and
infectious diseases 2009/10; 28(10): 1281-1284.
Mots-clés : EPIDEMIE; ACINETOBACTER BAUMANNII; ANTIBIOTIQUE; MULTIRESISTANCE; SOIN
INTENSIF; EPIDEMIOLOGIE; ANALYSE; PFGE; MORTALITE; CONTROLE; TYPAGE
An outbreak of multidrug-resistant Acinetobacter baumannii (MRAB) occurred over the course of a 27-week
period in our adult polyvalent intensive care unit (ICU). Twenty-one patients were affected, and 72 strains
were identified from different clinical samples. The strains were resistant to all antibiotics except for colistin
and ampicillin/sulbactam. Forty-nine MRAB strains collected from 18 patients were analysed by pulsed-field
gel electrophoresis (PFGE). This analysis revealed four highly-related PFGE types (genetic similarity index
>90%) termed 1, 2, 3 and 4, that were isolated in 13, seven, one, and three patients, respectively. A single
PFGE type was identified from five of ten patients with successive isolation of MRAB; in the other five
patients, two or three PFGE types were detected. This suggested phased evolution of PFGE types 2, 3 and
4 from PFGE type 1. Global mortality was high (13 patients; 62%). Non-survivors had higher APACHE II
scores than survivors on the date that MRAB was isolated (OR = 1.57; 95% CI [1.02, 2.44]). The outbreak
was controlled after implementation of an extensive infection control program.
NosoBase n° 25681
Les souches cliniques d'Acinetobacter baumannii tolérantes aux biocides et multirésitantes aux
antibiotiques sont associées à une formation élevée de biofilm
Rajamohan G; Srinivasan VB; Gebreyes WA. Biocide-tolerant multidrug-resistant Acinetobacter baumannii
clinical strains are associated with higher biofilm formation. The Journal of hospital infection 2009/11; 73(3):
287-289.
Mots-clés : BIOFILM; BIOCIDE; ACINETOBACTER; MULTIRESISTANCE
Antibiotique
NosoBase n° 25562
Prescription des antibiotiques en urologie reposant sur des preuves : synthèse de cinq ans de
résultats microbiologiques
Dasgupta R; Sullivan R; French G; O'Brien T. Evidence-based prescription of antibiotics in urology: a 5-year
review of microbiology. BJU international 2009/09; 104(6): 760-764.
Mots-clés : ANTIBIOTIQUE; MICROBIOLOGIE; PRESCRIPTION; UROLOGIE; URINE; PREVALENCE;
ANTIBIORESISTANCE; STREPTOCOCCUS; ESCHERICHIA COLI
Objective: To analyse the results of positive urine cultures over a 5-year period in a large hospital and
urology department (amongst both inpatients and outpatients), assess the prevalence of different organisms
and the resistance profiles of a range of antibiotics, and thus provide information on which organisms are
likely to cause urosepsis.
Methods: The use of antibiotics should be based on knowledge of which pathogens are present and what
resistance patterns are emerging, particularly relevant in surgical disciplines like urology, as antibiotics are
now routinely administered peri-operatively, whereby evidence-based prescription is preferable to generic
guidelines. We therefore examined almost 25,000 positive urine cultures in our hospital over a 5-year period,
and focused on the infections encountered amongst urology patients during this time.
Results: A significant proportion of inpatient urinary infection (40%) is caused by Gram-positive bacteria
such as Streptococcus faecalis, underlining the need for including Gram-positive cover during urological
prophylaxis. The commonest pathogen remains Escherichia coli among both inpatients and outpatients. The

ineffectiveness of common antibiotics such as ciprofloxacin and trimethoprim was identified, as was the
increase in gentamicin resistance.
Conclusion: We propose using an aminoglycoside with a penicillin for high-risk cases (e.g. endoscopic stone
surgery) while low-risk cases (e.g. flexible cystoscopy with no risk factors) might be managed without such
prophylaxis. Pathogenic patterns and resistance rates should be monitored regularly.
NosoBase n° 25596
Pseudomonas aeruginosa. Un phénomène de résistance bactérienne
Strateva T; Yordanov D. Pseudomonas aeruginosa - a phenomenon of bacterial resistance. Journal of
medical microbiology. 2009/09; 58(9): 1133-1148.
Mots-clés : FLUOROQUINOLONE; PSEUDOMONAS AERUGINOSA; ANTIBIORESISTANCE;
BETALACTAMINE; AMINOSIDE
Pseudomonas aeruginosa is one of the leading nosocomial pathogens worldwide. Nosocomial infections
caused by this organism are often hard to treat because of both the intrinsic resistance of the species (it has
constitutive expression of AmpC beta-lactamase and efflux pumps, combined with a low permeability of the
outer membrane), and its remarkable ability to acquire further resistance mechanisms to multiple groups of
antimicrobial agents, including beta-lactams, aminoglycosides and fluoroquinolones. P. aeruginosa
represents a phenomenon of bacterial resistance, since practically all known mechanisms of antimicrobial
resistance can be seen in it: derepression of chromosomal AmpC cephalosporinase; production of plasmid
or integron-mediated beta-lactamases from different molecular classes (carbenicillinases and extended-
spectrum beta-lactamases belonging to class A, class D oxacillinases and class B carbapenem-hydrolysing
enzymes); diminished outer membrane permeability (loss of OprD proteins); overexpression of active efflux
systems with wide substrate profiles; synthesis of aminoglycoside-modifying enzymes
(phosphoryltransferases, acetyltransferases and adenylyltransferases); and structural alterations of
topoisomerases II and IV determining quinolone resistance. Worryingly, these mechanisms are often
present simultaneously, thereby conferring multiresistant phenotypes. This review describes the known
resistance mechanisms in P. aeruginosa to the most frequently administrated antipseudomonal antibiotics:
beta-lactams, aminoglycosides and fluoroquinolones.
NosoBase n° 25723
Usage des antibiotiques et risques de colonisation et d'infection par des bactéries résistant aux
antibiotiques. Etude d'une population hospitalière
Tacconelli E; De Angelis G; Cataldo MA; Mantengoli E; Spanu T; Pan A et al. Antibiotic usage and risk of
colonization and infection with antibiotic-resistant bacteria: a hospital population-based study. Antimicrobial
agents and chemotherapy 2009/10; 53(10): 4264-4269.
Mots-clés : ANTIBIOTIQUE; ANTIBIORESISTANCE; COLONISATION; RISQUE; FACTEUR DE RISQUE;
COHORTE; PFGE; STAPHYLOCOCCUS AUREUS; METICILLINO-RESISTANCE; ENTEROCOCCUS;
VANCOMYCINE; PSEUDOMONAS AERUGINOSA; CARBAPENEME; CENTRE HOSPITALIER
UNIVERSITAIRE
Accurate assessment of risk factors for nosocomial acquisition of colonization by antibiotic-resistant bacteria
(ARB) is often confounded by scarce data on antibiotic use. A 12-month, nested, multicenter cohort study
was conducted. Target ARB were methicillin (meticillin)-resistant Staphylococcus aureus (MRSA),
vancomycin-resistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA).
Nares and rectal swabs were obtained before and after starting antibiotics. Pulsed-field gel electrophoresis
was done to define genetic relatedness of the strains. Primary outcomes were (i) the mean time, in days, for
acquisition of target ARB colonization in patients previously not colonized; (ii) the rate of acquisition per
1,000 antibiotic-days according to different classes of antibiotics; (iii) the rate of infection caused by the
same bacteria as those previously isolated in screening samples; and (iv) the risk factors for ARB
acquisition. In total, 6,245 swabs from 864 inpatients were processed. The rate of acquisition was 3%, 2%,
and 1% for MRSA, VRE, and CR-PA, respectively. The rate of acquisition of ARB per 1,000 antibiotic-days
was 14 for carbapenems, 9 for glycopeptides, and 6 for broad-spectrum cephalosporins and quinolones.
The highest rates of acquisition were observed for carbapenems in dialyzed and diabetic patients. Four risk
factors were independently associated with acquisition of target ARB: use of carbapenems, age of >70
years, hospitalization for >16 days, and human immunodeficiency virus infection. During the 30-day follow-

up, 4 among 42 patients newly colonized by ARB (9%) suffered from an infection due to the same bacteria
as those isolated in a previous screening sample. Colonizing and infecting strains from single patients were
genotypically identical. Identifying ARB colonization early during antibiotic therapy could target a high-risk
hospitalized population that may benefit from intervention to decrease the risk of subsequent nosocomial
infections
NosoBase n° 25571
Détection de bêta-lactamases à spectre élargi dans des bacilles à Gram négatif d'origine
nosocomiale
Tsering DC; Das S; Adhiakari L; Pal R; Singh T. Extended spectrum beta-lactamase detection in gram-
negative bacilli of nosocomial origin. Journal of global infectious diseases 2009/12; 1(2): 87-92.
Mots-clés : BETA-LACTAMASE A SPECTRE ELARGI; DEPISTAGE; BACILLE GRAM NEGATIF;
ANTIBIORESISTANCE; CEPHALOSPORINE TROISIEME GENERATION; ESCHERICHIA COLI;
PSEUDOMONAS; KLEBSIELLA PNEUMONIAE; MULTIRESISTANCE; PREVALENCE
Background: resistance to third generation cephalosporins by acquisition and expression of extended
spectrum beta lactamase (ESBL) enzymes among gram-negative bacilli is on a rise. The presence of ESBL
producing organisms significantly affects the course and outcome of an infection and poses a challenge to
infection management worldwide.
Materials and Methods: in the period from June 2007 to 2008, we collected 1489 samples from patients
suspected of nosocomial infection. The isolates were identified based on colony morphology and
biochemical reaction. Gram negative bacilli resistant to third generation cephalosporins were tested for
ESBL by double disc synergy test (DDST- a screening test) and then phenotypic confirmatory test.
Antimicrobial susceptibility testing was done by modified Kirby Bauer disc diffusion method.
Results: from the sample of 238 gram-negative bacilli, we isolated Escherichia coli, Pseudomonas
aeruginosa, Klebsiella pneumoniae, Citrobacter freundii, Proteus mirabilis, Morganella morganii and
Enterobacter cloacae. Following both methods, 34% isolates were ESBL-positive. The ESBL producing
isolates were significantly resistant (p < 0.01) to ampicillin, piperacillin, piperacillin/tazobactam,
trimethoprim/sulfamethoxazle, tetracycline, ciprofloxacin and gentamicin as compared to non-ESBL
producers. Multidrug resistance was significantly (p < 0.01) higher (69.14%) in ESBL positive isolates than
non-ESBL isolates (21.66%).
Conclusion: high prevalence of ESBL in our hospital cannot be ignored. ESBL producers can be detected by
DDST and phenotypic confirmatory test with equal efficacy. The sensitivity of screening test improved with
the use of more than one antibiotic and addition of one or two antibiotics would not increase cost and labor.
We recommend DDST using multiple antibiotics in all microbiology units as a routine screening test.
NosoBase n° 25657
Corrélation entre l'usage des antibiotiques et l'antibiorésistance dans un hôpital : observations dans
le temps et spécifiques par service
Willemsen I; Bogaers-Hofman D; Winters M; Kluytmans J. Correlation between antibiotic use and resistance
in a hospital: temporary and ward-specific observations. Infection 2009/10; 37(5): 432-437.
Mots-clés : ANTIBIOTIQUE; ANTIBIORESISTANCE; PREVALENCE; CIPROFLOXACINE;
BETALACTAMINE
Objectives: The objectives of this study were to determine (1) the increase in antimicrobial resistance to
frequently used antibiotics in the hospital setting over time and (2) the correlation between the amount of
use of an antibiotic in a specific medical specialty and the observed resistance to that antibiotic in that
specialty.
Method: The total use of antibiotics and the use of ciprofloxacin (CIP), co-amoxicillin + clavulanic acid
(AMCL) and first- and second-generation cephalosporins (CEF), respectively, in individual medical
specialties were measured between 2001 and 2006 by means of prevalence surveys (two per year). The
antimicrobial susceptibility patterns among E. coli isolated from hospitalized patients between 2003 and
2006 were obtained from the Laboratory Information System. Trends over time and correlation between use
and resistance were calculated.
Results: 6,639 patients were included in the prevalence surveys, of whom 3.0% (195) were treated with CIP,
9.7% (642) with AMCL, and 3.5% (232) with CEF. 4,790 E. coli isolates were obtained from hospitalized
patients. Resistance to all antibiotics significantly increased over time, with the regression line showing that

the strongest increase in resistance was for CIP (2.6% per year). There were large variations in antimicrobial
use between various medical specialties. A significant correlation was found between the ward-specific
prevalence of use and the percentage of resistance for CIP (R = 0.81, p < 0.001) and AMCL (R = 0.82, p =
0.003).
Conclusion: At the level of individual medical specialties within one hospital, a higher prevalence of
antimicrobial use among patients was associated with a significantly higher observed antimicrobial
resistance. The use of CIP was associated with a stronger increase in resistance than the use of beta-
lactams.
Bactériémie
NosoBase n° 25689
Variations saisonnières des bactériémies à Escherichia coli : étude de population
Al-Hasan MN; Lahr BD; Eckel-Passow JE; Baddour LM. Seasonal variation in Escherichia coli bloodstream
infection: a population-based study. Clinical microbiology and infection 2009/10; 15(10): 947-950.
Mots-clés : ESCHERICHIA COLI; BACTERIEMIE; TAUX; INFECTION COMMUNAUTAIRE;
EPIDEMIOLOGIE; INCIDENCE
Seasonal variation in the rates of infection with certain Gram-negative organisms has been previously
examined in tertiary-care centres. We performed a population-based investigation to evaluate the seasonal
variation in Escherichia coli bloodstream infection (BSI). We identified 461 unique patients in Olmsted
County, Minnesota, from 1 January 1998 to 31 December 2007, with E. coli BSI. Incidence rates (IR) and IR
ratios were calculated using Rochester Epidemiology Project tools. Multivariable Poisson regression was
used to examine the association between the IR of E. coli BSI and average temperature. The age- and
gender-adjusted IR of E. coli BSI per 100 000 person-years was 50.2 (95% CI 42.9-57.5) during the
warmest 4 months (June through September) compared with 37.1 (95% CI 32.7-41.5) during the remainder
of the year, resulting in a 35% (95% CI 12-66%) increase in IR during the warmest 4 months. The average
temperature was predictive of increasing IR of E. coli BSI (p 0.004); there was a 7% (95% CI 2-12%)
increase in the IR for each 10-degree Fahrenheit (c. 5.5 degrees C) increase in average temperature. To our
knowledge, this is the first study to demonstrate seasonal variation in E. coli BSI, with a higher IR during the
warmest 4 months than during the remainder of the year.
NosoBase n° 25668
Corrélation des incidences des bactériémies nosocomiales : étude écologique
Benet T; Vanhems P. Correlation of nosocomial bloodstream infection incidences: an ecological study.
The Journal of hospital infection 2009/11; 73(3): 217-224.
Mots-clés : INCIDENCE; BACTERIEMIE; EPIDEMIOLOGIE; PREVENTION; ETUDE PROSPECTIVE; SOIN
INTENSIF; HEMATOLOGIE; CENTRE HOSPITALIER UNIVERSITAIRE; HEMOCULTURE; TAUX
This study aimed to correlate nosocomial bloodstream infections (NBIs) across time against the ecological
effect of infection control activities. All patients hospitalised >/=48h in the haematology and intensive care
departments of a university hospital and discharged between 1 January 2004 and 30 June 2006 were
prospectively included. The case definition of NBI infection was: (1) at least one positive blood culture
justified by clinical signs, or (2) at least two positive blood cultures when the micro-organism was one of the
following: coagulase-negative staphylococci, Bacillus spp. (except Bacillus anthracis), Corynebacterium
spp., Propionibacterium spp., Micrococcus spp., or other commensal with similar pathogenicity, if occurring
>/=48h after patient admission. NBI incidences were correlated in quarterly intervals using Spearman's test
and linear regression. In total, 3829 patients accounting for 46 474 patient-days at risk were included. We
identified 101 NBIs in intensive care and 286 NBIs in haematology. There was a correlation between NBI
incidence in haematology with the NBI incidence in intensive care (r=0.68, P=0.042). The linear model for
NBI incidences between departments was R(2)=0.52, with a positive trend (P=0.029). A common
determinant such as improved hygiene measures is the most likely reason for this association.
NosoBase n° 25424
Taux de mortalité attribuable aux bactériémies à Klebsiella pneumoniae résistant aux carbapénèmes