Search tips
Search criteria

Results 1-25 (69)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
more »
1.  First multicenter study on multidrug resistant bacteria carriage in Chinese ICUs 
BMC Infectious Diseases  2015;15:358.
The importance of multidrug-resistant organisms (MDRO) in Chinese hospitals is not clearly delineated. Thus we sought to assess the prevalence of MDRO in Chinese intensive care units (ICUs).
Prospective study of inpatients admitted consecutively to eight ICUs in four Chinese cities in 2009–10. Admission and weekly screenings were performed by using selective media for methicillin resistant Staphylococcus aureus, extended-spectrum beta-lactamase-producing Enterobacteriaceae, Acinetobacter and Pseudomonas aeruginosa. For the two latters, resistance to ceftazidime defined MDRO. Backward logistic regression models were designed to assess factors independently associated with MDRO carriage on admission and MDRO acquisition within ICUs.
686 patients were included, and the MDRO prevalence rate on admission was 30.5 % (32.7 % for ESBL-positive Enterobacteriaceae, 3.2 % for MRSA). Antibiotic treatment prior to ICU admission was independently associated with carriage on admission (OR: 1.4) in multivariate analysis. A total of 104 patients acquired ≥1 MDRO in ICU (overall attack rate: 23.7 %; 14.9 % for ESBL-positive Enterobacteriaceae, and 5.1 % for MRSA). The MDRO attack rate increased from 13.2 % in the first week to 82.1 % for ICU stay > 3 weeks. Duration of antibiotic exposure (OR: 1.16; 1.1–1.2) and prior antibiotic treatment before ICU (OR: 2.1; 1.1–3.3) were associated with MDRO acquisition in multivariate analysis. The MDRO prevalence rate on ICU discharge was 51.2 % and the global prevalence density rate 71 per 1000 hospital-days.
More than one out of two patients was MDRO carrier on ICU discharge in Chinese hospitals. This is the result of the combination of a high MDRO prevalence rate on ICU admission and a high MDRO acquisition rate within ICU.
PMCID: PMC4545921  PMID: 26290050
3.  Imipenem, Meropenem, or Doripenem To Treat Patients with Pseudomonas aeruginosa Ventilator-Associated Pneumonia 
Only limited data exist on Pseudomonas aeruginosa ventilator-associated pneumonia (VAP) treated with imipenem, meropenem, or doripenem. Therefore, we conducted a prospective observational study in 169 patients who developed Pseudomonas aeruginosa VAP. Imipenem, meropenem, and doripenem MICs for Pseudomonas aeruginosa isolates were determined using Etests and compared according to the carbapenem received. Among the 169 isolates responsible for the first VAP episode, doripenem MICs were lower (P < 0.0001) than those of imipenem and meropenem (MIC50s, 0.25, 2, and 0.38, respectively); 61%, 64%, and 70% were susceptible to imipenem, meropenem, and doripenem, respectively (P was not statistically significant). Factors independently associated with carbapenem resistance were previous carbapenem use (within 15 days) and mechanical ventilation duration before VAP onset. Fifty-six (33%) patients had at least one VAP recurrence, and 56 (33%) died. Factors independently associated with an unfavorable outcome (recurrence or death) were a high day 7 sequential organ failure assessment score and mechanical ventilation dependency on day 7. Physicians freely prescribed a carbapenem to 88 patients: imipenem for 32, meropenem for 24, and doripenem for 32. The remaining 81 patients were treated with various antibiotics. Imipenem-, meropenem-, and doripenem-treated patients had similar VAP recurrence rates (41%, 25%, and 22%, respectively; P = 0.15) and mortality rates (47%, 25%, and 22%, respectively; P = 0.07). Carbapenem resistance emerged similarly among patients treated with any carbapenem. No carbapenem was superior to another for preventing carbapenem resistance emergence.
PMCID: PMC3957866  PMID: 24342638
4.  Illustration of the Difficulty of Identifying Streptococcus equi Strains at the Subspecies Level through a Case of Endocarditis in an Immunocompetent Man 
Journal of Clinical Microbiology  2014;52(2):688-691.
We report a case of endocarditis caused by Streptococcus equi in an immunocompetent patient who was subsequently cured after appropriate antibiotherapy and cardiac surgery. However, it was challenging to identify the strain to the subspecies level, which highlights the necessity of developing reliable molecular tools to discriminate between the subspecies.
PMCID: PMC3911343  PMID: 24478515
5.  Evaluation of the βLacta Test, a Rapid Test Detecting Resistance to Third-Generation Cephalosporins in Clinical Strains of Enterobacteriaceae 
Journal of Clinical Microbiology  2013;51(12):4012-4017.
For decades, third-generation cephalosporins (3GC) have been major drugs used to treat infections due to Enterobacteriaceae; growing resistance to these antibiotics makes the rapid detection of such resistance important. The βLacta test is a chromogenic test developed for detecting 3GC-resistant isolates from cultures on solid media within 15 min. A multicenter prospective study conducted in 5 French and Belgian hospitals evaluated the performance of this test on clinical isolates. Based on antibiotic susceptibility testing, strains resistant or intermediate to cefotaxime or ceftazidime were classified as 3GC resistant, and molecular characterization of this resistance was performed. The rates of 3GC resistance were 13.9% (332/2,387) globally, 9.4% in Escherichia coli (132/1,403), 25.6% in Klebsiella pneumoniae (84/328), 30.3% in species naturally producing inducible AmpC beta-lactamases (109/360), and 5.6% in Klebsiella oxytoca and Citrobacter koseri (7/124). The sensitivities and specificities of the βLacta test were, respectively, 87.7% and 99.6% overall, 96% and 100% for E. coli and K. pneumoniae, and 67.4% and 99.6% for species naturally producing inducible AmpC beta-lactamase. False-negative results were mainly related to 3GC-resistant strains producing AmpC beta-lactamase. Interestingly, the test was positive for all 3GC-resistant extended-spectrum beta-lactamase-producing isolates (n = 241). The positive predictive value was 97% and remained at ≥96% for prevalences of 3GC resistance ranging between 10 and 30%. The negative predictive values were 99% for E. coli and K. pneumoniae and 89% for the species producing inducible AmpC beta-lactamase. In conclusion, the βLacta test was found to be easy to use and efficient for the prediction of resistance to third-generation cephalosporins, particularly in extended-spectrum beta-lactamase-producing strains.
PMCID: PMC3838025  PMID: 24068012
6.  First Evaluation of Drug-Resistant Mycobacterium tuberculosis Clinical Isolates from Congo Revealed Misdetection of Fluoroquinolone Resistance by Line Probe Assay Due to a Double Substitution T80A-A90G in GyrA 
PLoS ONE  2014;9(4):e95083.
Tuberculosis (TB) is one of the major public health problems in Congo. However, data concerning Mycobacterium tuberculosis drug resistance are lacking because of the insufficient processing capacity. So, the aim of this study was to investigate for the first time the resistance patterns and the strain lineages of a sample of M. tuberculosis complex (MTBC) isolates collected in the two main cities of Congo.
Over a 9-day period, 114 smear-positive sputa isolated from 114 patients attending centers for the diagnosis and treatment of TB in Brazzaville and Pointe Noire were collected for culture and drug susceptibility testing (DST). Detection of mutations conferring drug resistance was performed by using line probe assays (GenoType MTBDRplus and MTBDRsl) and DNA sequencing. Strain lineages were determined by MIRU-VNTR genotyping.
Of the 114 sputa, 46 were culture positive for MTBC. Twenty-one (46%) were resistant to one or more first-line antiTB drugs. Of these, 15 (71%) were multidrug resistant (MDR). The most prevalent mutations involved in rifampin and isoniazid resistance, D516V (60%) in rpoB and S315T (87%) in katG respectively, were well detected by MTBDRplus assay. All the 15 MDR strains were susceptible to fluoroquinolone and injectable second-line drug. No mutation was detected in the rrs locus involved in resistance to amikacin and capreomycin by both the MTBDRsl assay and DNA sequencing. By contrast, 9 MDR strains belonging to the same cluster related to T-family were identified as being falsely resistant to fluoroquinolone by the MTBDRsl assay due to the presence of a double substitution T80A-A90G in GyrA.
Taken together, these data revealed a possible spread of a particular MDR clone in Congo, misidentified as fluoroquinolone resistant by MTBDRsl assay. Thus, this test cannot replace gold-standard culture method and should be interpreted carefully in view of the patient's native land.
PMCID: PMC3990612  PMID: 24743770
7.  Impact of Fluoroquinolone Resistance on Bactericidal and Sterilizing Activity of a Moxifloxacin-Containing Regimen in Murine Tuberculosis 
It has been shown previously that fluoroquinolone resistance (defined by resistance to at least 2 mg/liter ofloxacin) has a different impact on moxifloxacin monotherapy depending on the mutation in the sole fluoroquinolone target in Mycobacterium tuberculosis, i.e., DNA gyrase. Since tuberculosis treatment relies on multidrug therapy, we wished to determine the impact of fluoroquinolone resistance on the bactericidal and sterilizing activity of a second-line antituberculous regimen containing moxifloxacin. A total of 280 mice were inoculated with the wild-type Mycobacterium tuberculosis H37Rv strain or one of 3 isogenic fluoroquinolone-resistant mutant strains with increasing moxifloxacin resistance (the GyrB D500N, GyrA A90V, and GyrA D94G strains) and then treated for 6 months with a second-line regimen containing moxifloxacin, pyrazinamide, and ethionamide supplemented with amikacin during the first 2 months. Mice were sacrificed during treatment for measurement of bactericidal activity and 3 months after treatment completion for measurement of relapse rates (sterilizing activity). The CFU counts decreased faster in mice inoculated with the wild type than in mice inoculated with the mutant strains. The relapse rate after treatment completion was different among mice inoculated with mutant strains in relation to the drug resistance level: wild type, 0%; GyrB D500N strain, 33%; GyrA A90V strain, 50%; and GyrA D94G strain, 86%. The relapse rate observed with the GyrB D500N strain was the only one not statistically different from that observed with the wild-type strain. We demonstrated that the impact on sterilizing activity of the most active second-line drug regimen containing moxifloxacin depends on the MIC of moxifloxacin. We suggest that the precise level of moxifloxacin resistance be determined for all strains resistant to 2 mg/liter ofloxacin.
PMCID: PMC3754299  PMID: 23836169
8.  Concomitant Multidrug-resistant Pulmonary Tuberculosis and Susceptible Tuberculous Meningitis 
Emerging Infectious Diseases  2014;20(3):506-507.
PMCID: PMC3944847  PMID: 24565423
Mycobacterium tuberculosis; tuberculosis; drug resistance; heterogenous infection; compartmentalization; tuberculosis and other mycobacteria; France; Romania
9.  Rifampicin mono-resistant tuberculosis in France: a 2005–2010 retrospective cohort analysis 
Rifampicin resistance is a risk factor for poor outcome in tuberculosis. Therefore, we sought to describe the characteristics and management of Rifampicin monoresistant (RMR) tuberculosis (TB) in France.
We conducted a retrospective cohort analysis in 2012 on RMR TB patients diagnosed in France between 2005 and 2010 by using a national laboratory network. A standardized questionnaire was used to collect basic demographic data, region of birth, history of TB, HIV-coinfection, alcohol use, and antituberculosis treatment. Outcome was assessed after at least 18 months of follow-up.
A total of 39 patients with RMR TB were reported (0.12% of all TB cases). Overall, 19 (49%) had a previous history of treatment, 9 (23%) were HIV-coinfected, and 24 (62%) were smear-positive. Patient with secondary RMR were more likely to have alcohol abuse (P = 0.04) and HIV-coinfection (p = 0.04). Treatment outcome could be assessed for 30 patients, the nine others being dead or lost to follow-up. A total of 20 (67%) of the 30 assessed were cured, 3 (10%) died, 3 (10%) relapsed, and 4 (13%) were lost to follow up. Four (13%) received less than 6 months of treatment, 3 did not have any modification of the standardized regimen, 13 (43%) received fluoroquinolones, 4 (13%) aminoglycosides, and 8 (26%) a combination of both.
RMR TB is a rare disease in France, and its management was heterogeneous. The lack of treatment standardization may be a consequence of low expertise and may lead to the unsatisfactory low success rate.
PMCID: PMC3898244  PMID: 24410906
Rifampicin; Mycobacterium tuberculosis; Monoresistance; Management
10.  Antimicrobial resistance: a global view from the 2013 World Healthcare-Associated Infections Forum 
Antimicrobial resistance (AMR) is now a global threat. Its emergence rests on antimicrobial overuse in humans and food-producing animals; globalization and suboptimal infection control facilitate its spread. While aggressive measures in some countries have led to the containment of some resistant gram-positive organisms, extensively resistant gram-negative organisms such as carbapenem-resistant enterobacteriaceae and pan-resistant Acinetobacter spp. continue their rapid spread. Antimicrobial conservation/stewardship programs have seen some measure of success in reducing antimicrobial overuse in humans, but their reach is limited to acute-care settings in high-income countries. Outside the European Union, there is scant or no oversight of antimicrobial administration to food-producing animals, while evidence mounts that this administration leads directly to resistant human infections. Both horizontal and vertical infection control measures can interrupt transmission among humans, but many of these are costly and essentially limited to high-income countries as well. Novel antimicrobials are urgently needed; in recent decades pharmaceutical companies have largely abandoned antimicrobial discovery and development given their high costs and low yield. Against this backdrop, international and cross-disciplinary collaboration appears to be taking root in earnest, although specific strategies still need defining. Educational programs targeting both antimicrobial prescribers and consumers must be further developed and supported. The general public must continue to be made aware of the current scale of AMR’s threat, and must perceive antimicrobials as they are: a non-renewable and endangered resource.
PMCID: PMC4131211  PMID: 24237856
Antimicrobial resistance; Antimicrobial conservation; Antibiotic stewardship; Infection control; Hand hygiene; Surveillance networks; Care bundles; Environment; Regulations; Human medicine; Animal medicine; Global health; World Healthcare-Associated Infections Forum
11.  Resistance of M. leprae to Quinolones: A Question of Relativity? 
Multidrug resistant leprosy, defined as resistance to rifampin, dapsone and fluoroquinolones (FQ), has been described in Mycobacterium leprae. However, the in vivo impact of fluoroquinolone resistance, mainly mediated by mutations in DNA gyrase (GyrA2GyrB2), has not been precisely assessed. Our objective was to measure the impact of a DNA gyrase mutation whose implication in fluoroquinolone resistance has been previously demonstrated through biochemical studies, on the in vivo activity of 3 fluoroquinolones: ofloxacin, moxifloxacin and garenoxacin.
Methodology/Principal Findings
We used the proportional bactericidal method. 210 four-week-old immunodeficient female Nude mice (NMRI-Foxn1nu/Foxn1nu) were inoculated in the left hind footpad with 0.03 ml of bacterial suspension containing 5×103, 5×102, 5×101, and 5×100 M. leprae AFB organisms of strain Hoshizuka-4 which is a multidrug resistant strain harboring a GyrA A91V substitution. An additional subgroup of 10 mice was inoculated with 5×10−1 bacilli in the untreated control group. The day after inoculation, subgroups of mice were treated with a single dose of ofloxacin, moxifloxacin, garenoxacin or clarithromycin at 150 mg/kg dosing. 12 months later mice were sacrificed and M. leprae bacilli were numbered in the footpad. The results from the untreated control group indicated that the infective inoculum contained 23% of viable M. leprae. The results from the moxifloxacin and garenoxacin groups indicated that a single dose of these drugs reduced the percentage of viable M. leprae by 90%, similarly to the reduction observed after a single dose of the positive control drug clarithromycin. Conversely, ofloxacin was less active than clarithromycin.
DNA gyrase mutation is not always synonymous of lack of in vivo fluoroquinolone activity in M. leprae. As for M. tuberculosis, in vivo studies allow to measure residual antibiotic activity in case of target mutations in M. leprae.
Author Summary
Although there is efficient multidrug therapy to cure leprosy, the transmission of M. leprae is still active, leading to 219,000 new cases in 2011. Drug resistant leprosy has been described and may prevent eradication of the disease, notably multidrug resistant defined as resistance to rifampin, dapsone and fluoroquinolones (FQ). Resistance to FQ is due to mutations in DNA gyrase. We used a mouse model to measure the impact of DNA gyrase mutations on in vivo FQ activity. All the FQ tested showed in vivo activity against the mutant tested (A91V mutant in subunit A of DNA gyrase). However, whereas ofloxacin was less active than the control treatment clarithromycin, it appeared that latter generation fluoroquinolones moxifloxacin and garenoxacin were as active as clarithromycin. Our results demonstrate that DNA gyrase mutation is not synonymous of total lack of in vivo FQ activity against M. leprae. Therefore, as for M. tuberculosis, in vivo studies are mandatory in order to measure the impact of DNA gyrase mutations on treatment efficacy against M. leprae.
PMCID: PMC3828155  PMID: 24244784
12.  Whole-Genome Sequence of Mycobacterium abscessus Clinical Strain V06705 
Genome Announcements  2013;1(5):e00690-13.
Infection caused by Mycobacterium abscessus strains is a growing cause of concern in both community-acquired and health care-associated diseases, as these organisms naturally display multiple drug resistances. We report an annotated draft genome sequence of M. abscessus strain V06705 obtained from a patient in France.
PMCID: PMC3764416  PMID: 24009121
13.  Different Factors Associated with CTX-M-Producing ST131 and Non-ST131 Escherichia coli Clinical Isolates 
PLoS ONE  2013;8(9):e72191.
To determine factors associated with CTX-M-producing ST131 Escherichia coli which is the worldwide predominant lineage among CTX-M-producing E. coli isolates.
Consecutive inpatients with a clinical sample positive for CTX-M-producing E. coli and considered as cases in a previous 8-month (2008–2009) case-control study performed in ten university hospitals in the Paris area were included in the present sub-population study. Patients with a CTX-M-producing ST131 E. coli clinical isolate were compared with those with a CTX-M-producing non-ST131 E. coli clinical isolate with regard to 66 variables. Variables were first compared using univariate logistic regression, then a multivariate analysis using a backward selection with variables with p-value <0.1 in univariate analysis was carried out.
Fifty-five patients with a CTX-M-producing ST131 E. coli clinical isolate were compared to 97 patients with a CTX-producing non-ST131 E. coli clinical isolate. Multivariate analysis showed that only previous residence in long term care facilities (OR = 4.4; 95% CI = 1.3–14.7) was positively associated with a CTX-M-producing ST131 E. coli isolate. However, it also showed that regular consumption of poultry products (OR = 0.2; 95% CI = 0.1–0.6), having had at least one device in the preceding 6 months (OR = 0.3; 95% CI = 0.1–0.7) and stay in ICU (OR = 0.2; 95% CI = 0.05–0.8) were negatively associated with isolation of CTX-M-producing ST131 E. coli from clinical samples.
This study provides more insight into the epidemiological features of ST131 and non-ST131 E. coli producing CTX-M enzymes. It shows, for the first time, that isolation of CTX-M-producing ST131 E. coli from clinical samples is not linked to consumption of various foods and confirms that residence in long term care facilities is a predictor of these isolates.
PMCID: PMC3762868  PMID: 24023730
14.  Complete Nucleotide Sequence of the First KPC-2- and SHV-12-Encoding IncX Plasmid, pKpS90, from Klebsiella pneumoniae 
We report the complete nucleotide sequence of the pKpS90 plasmid, carrying the blaKPC-2 and blaSHV-12 genes. This plasmid was isolated from a sequence type 258 (ST258) Klebsiella pneumoniae strain responsible for an outbreak in a French university hospital in 2009. pKpS90 is a 53,286-bp plasmid that belongs to the IncX incompatibility group. pKpS90 consists of a backbone from IncX plasmids, in which the KPC-2-encoding Tn4401 transposon and a blaSHV-12-encoding region have been inserted.
PMCID: PMC3535902  PMID: 23089759
15.  Phylogenetic Distribution of CTX-M- and Non-Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolates: Group B2 Isolates, Except Clone ST131, Rarely Produce CTX-M Enzymes 
Journal of Clinical Microbiology  2012;50(9):2974-2981.
Escherichia coli is the species most frequently associated with clinical infections by extended-spectrum-β-lactamase (ESBL)-producing isolates, with the CTX-M ESBL enzymes being predominant and found in genetically diverse E. coli isolates. The main objective of this study was to compare, on the basis of a case-control design, the phylogenetic diversity of 152 CTX-M-producing and 152 non-ESBL-producing clinical E. coli isolates. Multilocus sequence typing revealed that even though CTX-M enzymes were largely disseminated across the diversity of E. coli isolates, phylogenetic group B2 showed a particularly heterogeneous situation. First, clone ST131 of group B2 was strongly associated with CTX-M production (55 [79%] of 70 isolates), with CTX-M-15 being predominant. Second, the remaining members of group B2 were significantly less frequently associated with CTX-M production (9 [12%] of 75) than E. coli phylogenetic groups A, B1, and D (88 [55%] of 159). CTX-M-producing ST131 E. coli isolates were significantly more frequent in patients hospitalized in geriatric wards or long-term care facilities. Besides, the non-ESBL ST131 isolates significantly more frequently showed resistance to penicillins than the non-ESBL, non-ST131 isolates did. In conclusion, the present study emphasizes the particular antimicrobial resistance and epidemiologic characteristics of clone ST131 within group B2, which could result from the higher antibiotic exposure of this clone, as it is the predominant clone of group B2 carried in the human gut.
PMCID: PMC3421780  PMID: 22760036
16.  New Mutations in the Mycobacterial ATP Synthase: New Insights into the Binding of the Diarylquinoline TMC207 to the ATP Synthase C-Ring Structure 
TMC207 is a new antituberculous drug belonging to the diarylquinoline class which very efficiently inhibits the ATP synthase of mycobacteria such as Mycobacterium tuberculosis, one of the most important pathogens in the world. In order to map the amino acid residues involved in the binding of the drug, we have selected in vitro TMC207-resistant mutants from M. tuberculosis and diverse atypical mycobacteria. Six distinct mutations, Asp28→Gly, Asp28→Ala, Leu59→Val, Glu61→Asp, Ala63→Pro, and Ile66→Met, have been identified in the subunit c forming a C ring in the ATP synthase. They were studied by evaluating the levels of resistance that they confer in the selected clones and by using an isogenic complementation system in Mycobacterium smegmatis. The rates of increase of TMC207 MIC values (8- to 133-fold) were interpreted by constructing by homology modeling a structure of the mycobacterial C ring which was used for docking simulations with TMC207. Our results suggest that the residues found to be mutated in the resistant clones, together with a tyrosine specifically conserved at position 64 in mycobacteria, define a cleft located between two adjacent c subunits in the C ring. This cleft, which encompasses the proton-binding site (Glu61), is well fitted to bind TMC207 at the level of the bromoquinoline moiety, with the drug being anchored by several ionic, hydrogen, and halogen bonds with residues Glu61, Tyr64, and Asp28, respectively. These data shed light on the molecular interactions allowing TMC207 to bind specifically and efficiently at the level of the proton-binding site of the mycobacterial C ring.
PMCID: PMC3346594  PMID: 22354303
17.  Extending the Definition of the GyrB Quinolone Resistance-Determining Region in Mycobacterium tuberculosis DNA Gyrase for Assessing Fluoroquinolone Resistance in M. tuberculosis 
Fluoroquinolone (FQ) resistance is emerging in Mycobacterium tuberculosis. The main mechanism of FQ resistance is amino acid substitution within the quinolone resistance-determining region (QRDR) of the GyrA subunit of DNA gyrase, the sole FQ target in M. tuberculosis. However, substitutions in GyrB whose implication in FQ resistance is unknown are increasingly being reported. The present study clarified the role of four GyrB substitutions identified in M. tuberculosis clinical strains, two located in the QRDR (D500A and N538T) and two outside the QRDR (T539P and E540V), in FQ resistance. We measured FQ MICs and also DNA gyrase inhibition by FQs in order to unequivocally clarify the role of these mutations in FQ resistance. Wild-type GyrA, wild-type GyrB, and mutant GyrB subunits produced from engineered gyrB alleles by mutagenesis were overexpressed in Escherichia coli, purified to homogeneity, and used to reconstitute highly active gyrase complexes. MICs and DNA gyrase inhibition were determined for moxifloxacin, gatifloxacin, ofloxacin, levofloxacin, and enoxacin. All these substitutions are clearly implicated in FQ resistance, underlining the presence of a hot spot region housing most of the GyrB substitutions implicated in FQ resistance (residues NTE, 538 to 540). These findings help us to refine the definition of GyrB QRDR, which is extended to positions 500 to 540.
PMCID: PMC3318379  PMID: 22290942
18.  Chemotherapy-Associated Changes of Histopathological Features of Mycobacterium ulcerans Lesions in a Buruli Ulcer Mouse Model 
Combination chemotherapy with rifampin and streptomycin (RIF-STR) for 8 weeks is currently recommended by the WHO as the first-line treatment for Mycobacterium ulcerans infection (Buruli ulcer). To gain better insight into the mode of action of these antibiotics against established M. ulcerans infection foci and to characterize recovery of local immune responses during chemotherapy, we conducted a detailed histopathological study of M. ulcerans-infected and RIF-STR-treated mice. Mice were inoculated with M. ulcerans in the footpad and 11 weeks later treated with RIF-STR. Development of lesions during the first 11 weeks after infection and subsequent differences in disease progression between RIF-STR-treated and untreated mice were studied. Changes in histopathological features, footpad swelling, and number of CFU were analyzed. After inoculation with M. ulcerans, massive infiltrates dominated by polymorphonuclear leukocytes developed at the inoculation site but did not prevent bacterial multiplication. Huge clusters of extracellular bacteria located in large necrotic areas and surrounded by dead leukocytes developed in the untreated mice. Chemotherapy with RIF-STR led to a rapid drop in CFU associated with loss of solid Ziehl-Neelsen staining of acid-fast bacilli. Development of B-lymphocyte clusters and of macrophage accumulations surrounding the mycobacteria demonstrated the resolution of local immune suppression. Results demonstrate that the experimental M. ulcerans mouse infection model will be a valuable tool to investigate efficacy of new treatment regimens and of candidate vaccines.
PMCID: PMC3264237  PMID: 22143518
19.  Detection of Antibiotic Resistance in Leprosy Using GenoType LepraeDR, a Novel Ready-To-Use Molecular Test 
Although leprosy is efficiently treated by multidrug therapy, resistance to first-line (dapsone, rifampin) and to second-line drugs (fluoroquinolones) was described worldwide. Since Mycobacterium leprae is not growing in vitro, phenotypic susceptibility testing requires a one year experiment in the mouse model and this is rarely performed. Genetics on antibiotic resistance provide the basis for molecular tests able to detect for antibiotic resistance in leprosy.
Methodology/Principal Findings
A reverse hybridization DNA strip test was developed as the GenoType LepraeDR test. It includes DNA probes for the wild-type sequence of regions of rpoB, gyrA and folP genes and probes for the prevalent mutations involved in acquired resistance to rifampin, fluoroquinolones and dapsone, respectively. The performances of the GenoType LepraeDR test were evaluated by comparing its results on 120 M. leprae strains, previously studied for resistance by the reference drug in vivo susceptibility method in the mouse footpad and for mutations in the gene regions described above by PCR-sequencing. The results of the test were 100% concordant with those of PCR sequencing and the mouse footpad test for the resistant strains: 16 strains resistant to rifampin, 22 to dapsone and 4 to ofloxacin with mutations (numbering system of the M. leprae genome) in rpoB (10 S456L, 1 S456F, 1 S456M + L458V, 1 H451Y, 1 G432S + H451D, 1 T433I + D441Y and 1 Q438V), in folP1 (8 P55L, 3 P55R, 7 T53I, 3 T53A, 1 T53V) and gyrA (4 A91V), respectively. Concordance was 98.3% for the susceptible strains, two strains showing a mutation at the codon 447 that in fact was not conferring resistance as shown by the in vivo method.
The GenoType LepraeDR test is a commercially available test that accurately detects for antibiotic resistance in leprosy cases. The test is easy to perform and could be implemented in endemic countries.
Author Summary
Although leprosy is a curable disease using a combination of antibiotics for one year, the transmission is still active with 230,000 new cases in 2010. Drug resistance has been described and may prevent eradication of the disease. The infectious agent causing leprosy, Mycobacterium leprae, is not growing in vitro and antibiotic susceptibility testing is possible only in the mouse footpad model that requires a one year experiment. Consequently this testing is rarely done and antibiotic resistance rates in leprosy are unknown. This is the reason why we endeavored to set a new diagnosis test that detects for antibiotic resistance in M. leprae. The test is based on the method of a DNA strip test with a multiplex PCR followed by reverse hybridization. It was developed as an easy-to-use test and it will be available in endemic countries, where these kinds of strip tests are already used for detection of drug resistance in tuberculosis. The results of the new test, Genotype LepraeDR, performed on 120 M. leprae strains were concordant with those of the standard PCR sequencing and mouse footpad susceptibility testing.
PMCID: PMC3409109  PMID: 22860144
21.  DNA Gyrase Inhibition Assays Are Necessary To Demonstrate Fluoroquinolone Resistance Secondary to gyrB Mutations in Mycobacterium tuberculosis▿ 
Antimicrobial Agents and Chemotherapy  2011;55(10):4524-4529.
The main mechanism of fluoroquinolone (FQ) resistance in Mycobacterium tuberculosis is mutation in DNA gyrase (GyrA2GyrB2), especially in gyrA. However, the discovery of unknown mutations in gyrB whose implication in FQ resistance is unclear has become more frequent. We investigated the impact on FQ susceptibility of eight gyrB mutations in M. tuberculosis clinical strains, three of which were previously identified in an FQ-resistant strain. We measured FQ MICs and also DNA gyrase inhibition by FQs in order to clarify the role of these mutations in FQ resistance. Wild-type GyrA, wild-type GyrB, and mutant GyrB subunits produced from engineered gyrB alleles by mutagenesis were overexpressed in Escherichia coli, purified to homogeneity, and used to reconstitute highly active gyrase complexes. MICs and DNA gyrase inhibition were determined for moxifloxacin, gatifloxacin, ofloxacin, levofloxacin, and enoxacin. We demonstrated that the eight substitutions in GyrB (D473N, P478A, R485H, S486F, A506G, A547V, G551R, and G559A), recently identified in FQ-resistant clinical strains or encountered in M. tuberculosis strains isolated in France, are not implicated in FQ resistance. These results underline that, as opposed to phenotypic FQ susceptibility testing, the DNA gyrase inhibition assay is the only way to prove the role of a DNA gyrase mutation in FQ resistance. Therefore, the use of FQ in the treatment of tuberculosis (TB) patients should not be ruled out only on the basis of the presence of mutations in gyrB.
PMCID: PMC3186962  PMID: 21768507
22.  Ready for a world without antibiotics? The Pensières Antibiotic Resistance Call to Action 
Resistance to antibiotics has increased dramatically over the past few years and has now reached a level that places future patients in real danger. Microorganisms such as Escherichia coli and Klebsiella pneumoniae, which are commensals and pathogens for humans and animals, have become increasingly resistant to third-generation cephalosporins. Moreover, in certain countries, they are also resistant to carbapenems and therefore susceptible only to tigecycline and colistin. Resistance is primarily attributed to the production of beta-lactamase genes located on mobile genetic elements, which facilitate their transfer between different species. In some rare cases, Gram-negative rods are resistant to virtually all known antibiotics. The causes are numerous, but the role of the overuse of antibiotics in both humans and animals is essential, as well as the transmission of these bacteria in both the hospital and the community, notably via the food chain, contaminated hands, and between animals and humans. In addition, there are very few new antibiotics in the pipeline, particularly for Gram-negative bacilli. The situation is slightly better for Gram-positive cocci as some potent and novel antibiotics have been made available in recent years. A strong and coordinated international programme is urgently needed. To meet this challenge, 70 internationally recognized experts met for a two-day meeting in June 2011 in Annecy (France) and endorsed a global call to action ("The Pensières Antibiotic Resistance Call to Action"). Bundles of measures that must be implemented simultaneously and worldwide are presented in this document. In particular, antibiotics, which represent a treasure for humanity, must be protected and considered as a special class of drugs.
PMCID: PMC3436635  PMID: 22958833
antibiotic resistance; antibiotic stewardship; infection control; hand hygiene; surveillance networks; care bundles; environment; regulations; human medicine; animal medicine
23.  Twenty years of antimicrobial resistance control programme in a regional multi hospital institution, with focus on emerging bacteria (VRE and CPE) 
Assistance Publique-Hôpitaux de Paris (APHP), the largest public health care institution in France (38 hospitals, 23,000 beds, serving 11.6 millions inhabitants) launched in 1993 a long term programme to control and survey multidrug resistant bacteria (MDR).
AP-HP MDR programme consisted in successive waves of actions: bundle measures to survey and control cross transmission of MRSA and extended-spectrum betalactamase producing enterobacteria (ESBL) in 1993, large campaign to promote the use of alcohol-based hand rub solution (ABHRS) in 2001, specific strategy to quickly control the spread of emerging MDR (vancomycin resistant Enterococcus, VRE; carbapenemase producing enterobacteria, CPE) in 2006, large campaign to decrease antibiotics consumption in 2006.
Following this programme, the ABHRS consumption dramatically increased, the antibiotic consumption decreased by 10%, the incidence of MRSA, including MRSA bacteraemia, decreased by 2/3, all VRE and CPE events were rapidly controlled. However, the incidence of ESBL, mainly Klebsiella pneumoniae and Escherichia coli, that remained low and stable until 2003 increased markedly afterwards, justifying adapting our programme in the future.
A sustained and coordinated strategy can lead to control multidrug resistant bacteria at the level of a large multihospital institution.
PMCID: PMC3436665  PMID: 22958336
antibiotic resistance control; carbapenemase producing enterobacteria; CPE; vancomycin resistant enterococci; VRE; MRSA; quality programme; healthcare associated infections; HAI
24.  Patient's Origin and Lifestyle Associated with CTX-M-Producing Escherichia coli: A Case-Control-Control Study 
PLoS ONE  2012;7(1):e30498.
Global dissemination of Escherichia coli producing CTX-M extended-spectrum β-lactamases (ESBL) is a public health concern. The aim of the study was to determine factors associated with CTX-M- producing E. coli infections among patients hospitalised in the Assistance Publique-Hôpitaux de Paris, the largest hospital system in France (23 000 beds), through a prospective case-control-control study.
Methods/Principal Findings
From November 2008 to June 2009, 152 inpatients with a clinical sample positive for CTX-M-producing E. coli (cases), 152 inpatients with a clinical sample positive for non ESBL-producing E. coli on the day or within the three days following case detection (controls C1), and 152 inpatients with culture-negative clinical samples since the beginning of hospitalisation and until three days after case detection (controls C2) were included in ten hospitals of the Paris area. Factors studied were related to patient's origin, lifestyle and medical history as well as care during hospitalisation. Those independently associated with CTX-M-producing E. coli were determined. Three independent factors were common to the two case-control comparisons: birth outside of Europe (cases vs C1: OR1 = 2.4; 95%CI = [1.3–4.5] and cases vs C2: OR2 = 3.1; 95%CI = [1.4–7.0]), chronic infections (OR1 = 2.9; 95%CI = [1.3–6.9] and OR2 = 8.7; 95%CI = [2.0–39.7]), and antibiotic treatment between hospital admission and inclusion (OR1 = 2.0; 95%CI = [1.0–3.8] and OR2 = 3.3; 95%CI = [1.5–7.2]). Cases were also more likely to be (i) functionally dependent before hospitalisation than C2 (OR2 = 7.0; 95%CI = [2.1–23.5]) and (ii) living in collective housing before hospitalisation than C2 (OR2 = 15.2; 95%CI = [1.8–130.7]) when CTX-M-producing E. coli was present at admission.
For the first time, patient's origin and lifestyle were demonstrated to be independently associated with isolation of CTX-M-producing E. coli, in addition to health care-related factors.
PMCID: PMC3267726  PMID: 22299043
25.  Activity of Carbapenems Combined with Clavulanate against Murine Tuberculosis▿ 
Although beta-lactam antibiotics are not considered as antituberculous drugs, it has been recently shown that the combination of carbapenems and clavulanate is bactericidal in vitro. We evaluated in a murine model of tuberculosis the activity of carbapenems alone and combined with clavulanate against Mycobacterium tuberculosis. Swiss mice infected intravenously with 3 × 105 M. tuberculosis H37Rv were treated for 4 weeks with clavulanate alone or imipenem, meropenem, and ertapenem alone or combined with clavulanate, whereas a positive control group was treated with isoniazid, and a negative control group was held without treatment. The combination of imipenem or meropenem plus clavulanate significantly improved survival. Among groups of mice with 100% survival, only isoniazid reduced lung CFU counts; the carbapenem-clavulanate combinations did not prevent bacterial growth. Although less active than isoniazid, the combinations of imipenem or meropenem plus clavulanate improved the survival of mice infected with M. tuberculosis and should be further evaluated.
PMCID: PMC3101399  PMID: 21402832

Results 1-25 (69)