Samy Figueiredo

Acinetobacter radioresistens as a Silent Source of Carbapenem Resistance for Acinetobacter spp.

ABSTRACT Carbapenem resistance results mostly from the expression of acquired carbapenem-hydrolyzing oxacillinases in Acinetobacter baumannii. The blaOXA-23 oxacillinase gene is increasingly reported worldwide and may represent an emerging threat. Our goal was to identify the progenitor of that carbapenemase gene. A collection of 50 Acinetobacter sp. strains corresponding to several Acinetobacter species was screened for blaOXA-23-like genes by PCR and hybridization techniques. Five Acinetobacter radioresistens isolates that were susceptible to carbapenems harbored chromosomally encoded blaOXA-23-like genes. A similar plasmid backbone was identified in several blaOXA-23-positive A. baumannii and A. radioresistens isolates, further strengthening the vectors of exchanges for these blaOXA-23-like genes. Therefore, A. radioresistens, a commensal bacterial species which is identified on the skin of hospitalized and healthy patients (a property shared with A. baumannii), was identified as the source of the blaOXA-23 gene.

In Vivo Selection of Reduced Susceptibility to Carbapenems in Acinetobacter baumannii Related to ISAba1-Mediated Overexpression of the Natural blaOXA-66 Oxacillinase Gene

ABSTRACT Two clonally related Acinetobacter baumannii isolates, A1 and A2, were obtained from the same patient. Isolate A2, selected after an imipenem-containing treatment, showed reduced susceptibility to carbapenems. This resistance pattern was related to insertion of the ISAba1 element upstream of the naturally occurring blaOXA-66 carbapenemase gene as demonstrated by sequencing, reverse transcription-PCR analysis, and inactivation of the blaOXA-66 gene.

NDM-1-Producing Acinetobacter baumannii from Algeria

Over the last decade, nosocomial infections with Acinetobacter baumannii have been described with an increasing trend toward multidrug resistance, mostly in intensive care units (ICUs) ([6][1], [9][2], [11][3]). The main mechanism of resistance to carbapenems in A. baumannii is the production of

Overexpression of the Naturally Occurring blaOXA-51 Gene in Acinetobacter baumannii Mediated by Novel Insertion Sequence ISAba9

Resistance to carbapenems in Acinetobacter baumannii is increasingly reported and is mostly associated with expression of carbapenemases (3, 6). Those carbapenemases are most frequently carbapenem-hydrolyzing class D β-lactamases, which have been identified worldwide, including in Greece (4, 10). Four major subgroups of carbapenem-hydrolyzing class D β-lactamases have been identified in A. baumannii: the naturally occurring OXA-51/69-type β-lactamase and the acquired OXA-23, OXA-24/40 and OXA-58-type β-lactamases. Despite a weak catalytic activity, the naturally occurring OXA-51/69-type β-lactamases might contribute to carbapenem resistance by insertion of ISAba1 in the promoter region of the blaOXA-51/69-like genes (1, 8, 11). n nTwenty nonrepetitive carbapenem-resistant A. baumannii clinical isolates were isolated from August 2001 to November 2006 at the Papageorgiou General Hospital, Thessaloniki, Greece (Table u200b(Table1).1). All 20 isolates were resistant to imipenem, among which 8 were additionally resistant to meropenem (MICs ranging from 8 to 64 μg/ml) (Table u200b(Table1).1). No metallo-β-lactamase (MBL) production was detected by using Etest MBL strips (AB Biodisk, Solna, Sweden). Pulsed-field gel electrophoresis (PFGE) analysis was done as previously described (Bio-Rad, Ivry-sur-Seine, France) (5, 9) and showed that the 20 A. baumannii isolates exhibited 5 distinct PFGE profiles defining clones I to V (Table u200b(Table1).1). PCR experiments performed using primers specific for blaOXA-58-like, blaOXA-23-like, and blaOXA-24/40-like genes (12) showed that 16 isolates belonging to clones I, II, or III possessed the blaOXA-58 gene, whereas no isolate harbored the blaOXA-23 or blaOXA-40 genes. PCR experiments using primers specific for the naturally occurring blaOXA-51-like gene gave positive results for the 20 A. baumannii strains tested. In three clonally related and blaOXA-58-negative A. baumannii isolates, Ab2, Ab5, and Ab23, ISAba1 was identified upstream of the blaOXA-51 gene (11) (Table u200b(Table1).1). In isolate Ab5, the ISAba1 copy located immediately upstream of the blaOXA-51 gene was truncated by a novel insertion sequence named “ISAba9” (Fig. u200b(Fig.1).1). ISAba9 is 974 bp long and belongs to the IS982 family (http://www-is.biotoul.fr./). It possesses 17-bp inverted repeats and was bracketed by an 8-bp target site duplication (TTGTTTAA), which is likely the signature of a transposition process. ISAba9 was very recently identified in association with the blaRTG-4 gene in A. baumannii (7). We hypothesized that ISAba9 located upstream of the blaOXA-51 gene in isolate Ab5 might contribute to carbapenem resistance by providing promoter sequences leading to the overexpression of the blaOXA-51 gene, as observed with ISAba1 (2, 8, 11). Analysis of the genetic environment of the blaOXA-51 gene in Ab5 showed that ISAba1 provided −35 and −10 promoter sequences, as already described (1). In addition, a hybrid promoter made of a −35 box located inside ISAba9 and a −10 box located in ISAba1 with an optimal 17-bp spacing between the −35 and −10 boxes was identified (Fig. u200b(Fig.1).1). Quantitative analysis of the blaOXA-51 expression was performed by reverse transcription-PCR using the two clonally related isolates Ab2 and Ab5, as previously described (1). Transcriptional profile analysis indicated an eightfold increased expression of blaOXA-51 in the genetic structure containing ISAba1 and ISAba9 compared with ISAba1 alone upstream of this gene (mean ± standard deviation, 8 ± 5), using the 16S RNA gene as a housekeeping gene. PCR screening of the 20 A. baumannii isolates using primers specific for ISAba9 gave positive results for isolates Ab2, Ab3, Ab5, and Ab23, but ISAba9 was located upstream of the blaOXA-51-like gene only in isolate Ab5. n n n nFIG. 1. n nNucleotide sequence of the −35 and −10 putative promoter regions within ISAba1 described from isolates Ab2 (A) and Ab5 (B). The left inverted repeat (IRL) of ISAba1 and the right inverted repeat (IRR) of ISAba9 are shaded in gray, and ... n n n n n nTABLE 1. n nCharacteristics of A. baumannii isolates n n n nIn conclusion, we identified the novel insertion sequence ISAba9 as being involved in blaOXA-51 gene overexpression, thus contributing to carbapenem resistance in A. baumannii. ISAba9, after ISAba1, might be an additional tool for genetic plasticity of A. baumannii and, in particular, for acquisition of resistance.

OXA-134, a Naturally Occurring Carbapenem-Hydrolyzing Class D β-Lactamase from Acinetobacter lwoffii

ABSTRACT Acinetobacter lwoffii, a species whose natural habitat is the human skin, intrinsically possesses a chromosomal gene encoding a carbapenem-hydrolyzing class D β-lactamase, OXA-134. This species may therefore constitute a reservoir for carbapenemase genes that may spread among other Acinetobacter species.

Use of fresh frozen plasma: from the 2012 French guidelines to recent advances

Fresh frozen plasma (FFP) is widely used by anesthetists and/or intensivists managing bleeding patients. In this context, two clinical situations with different benefit/risk ratio for FFP transfusion should be distinguished: moderate or controlled hemorrhage on one side, and massive hemorrhage on the other. In the former situation, administration of FFP is most often ineffective, associated with potential side effects (pulmonary complications, product shortage) and should therefore be restricted. In case of massive hemorrhage, transfusion of FFP, red blood cells and platelets using a ratio close to 1:1:1 is recommended based on a large number of studies. A goal-directed strategy, based on the utilization of point-of-care hemostatic devices, might be used as an alternative or in combination with this ratio-driven strategy.

Impact of learners’ role (active participant-observer or observer only) on learning outcomes during high-fidelity simulation sessions in anaesthesia: A single center, prospective and randomised study

AIMnThe increasing use of high-fidelity simulation is limited by the imbalance between the growing number of students and the human resources available in such a way that all residents cannot play a role during scenarios. The learning outcomes of observers need to be studied.nnnMETHODSnThis prospective randomised study was approved by the institutional review board. Anaesthesia residents attending a one-day training session were enrolled. In each of the four scenarios, three residents played an active role while others observed in a separate room. All participants attended debriefing sessions. Residents were randomised between active participant-observer group (AP-O group) and observer group (O group). A similar questionnaire was distributed before, immediately after the session and after three months and included self-reported assessment of satisfaction, medical knowledge (noted 0-16), and non-technical skills.nnnRESULTSnA hundred and four questionnaires were analysed. Immediately after the simulation, a significant increase in medical knowledge was recorded but was higher in the AP-O group (6 [5-8] to 10 [8-11]/16) than in the O group (7 [5-8] to 9 [7-10]/16). High scores for non-technical skills were similarly observed in both groups. Satisfaction was high in both groups but was higher in the AP-O group (9 [8-9] versus 8 [8-9]/10, P=0.019). Decay of knowledge was observed for most main outcomes at three months.nnnCONCLUSIONnThis study suggests an immediate improvement of learning outcomes for both roles after immersive simulation but some learning outcomes may be better for residents engaged as players in scenarios.