Jean-Louis Gaillard

Characterization of Class 1 Integrons from Pseudomonas aeruginosa That Contain the blaVIM-2 Carbapenem-Hydrolyzing β-Lactamase Gene and of Two Novel Aminoglycoside Resistance Gene Cassettes

ABSTRACT Two clonally unrelated Pseudomonas aeruginosa clinical strains, RON-1 and RON-2, were isolated in 1997 and 1998 from patients hospitalized in a suburb of Paris, France. Both isolates expressed the class B carbapenem-hydrolyzing β-lactamase VIM-2 previously identified in Marseilles in the French Riviera. In both isolates, theblaVIM-2 cassette was part of a class 1 integron that also encoded aminoglycoside-modifying enzymes. In one case, two novel aminoglycoside resistance gene cassettes,aacA29a and aacA29b, were located at the 5′ and 3′ end of the blaVIM-2 gene cassette, respectively. The aacA29a and aacA29b gene cassettes were fused upstream with a 101-bp part of the 5′ end of theqacE cassette. The deduced amino acid sequence AAC(6′)-29a protein shared 96% identity with AAC(6′)-29b but only 34% identity with the aacA7-encoded AAC(6′)-I1, the closest relative of the AAC(6′)-I family enzymes. These aminoglycoside acetyltransferases had amino acid sequences much shorter (131 amino acids) than the other AAC(6′)-I enzymes (144 to 153 amino acids). They conferred resistance to amikacin, isepamicin, kanamycin, and tobramycin but not to gentamicin, netilmicin, and sisomicin.

Mycobacterium avium and Mycobacterium abscessus complex target distinct cystic fibrosis patient subpopulations

BACKGROUND Clinical observations suggest that Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MABSC) may affect cystic fibrosis (CF) patients with different characteristics and risk factors, but this has never been demonstrated within a single prospective cohort. METHODS We studied 50 MABSC-positive and 23 MAC-positive patients from a French prevalence study of non-tuberculous mycobacteria (NTM) in CF. Risk factors specifically associated with MABSC and MAC were analyzed by nested case-control studies, with two NTM-negative controls matched by age, sex and center for each case. RESULTS MAC-positive patients were significantly older than MABSC-positive patients (mean [SD] age, 23.1 [10.2] vs 17.4 [8.3] years, p=0.013), and were also older at CF diagnosis (mean [SD] age, 12.9 [16.1] vs 3.1 [7.7] years, p=0.015); they tended to be less frequent of the ΔF508/ΔF508 genotype (33.3 vs 61.1%, p=0.17) and to use pancreatic extracts less frequently (82.4 vs 97.6%, p=0.07). Risk factors identified by multivariate analysis were: i) in the MAC case-control study, an older age at CF diagnosis (p=0.004); ii) in the MABSC case-control study, at least one course of intravenous antibiotics (p=0.01) and more frequent isolation of Aspergillus (p=0.03). CONCLUSIONS MAC affects adult patients with a mild form of CF, whereas MABSC affects younger patients with more severe CF and more frequent intravenous antimicrobial treatment.

Comparing Mycobacterium massiliense and Mycobacterium abscessus lung infections in cystic fibrosis patients

BACKGROUND Mycobacterium massiliense is closely related to Mycobacterium abscessus and is also a frequent cause of mycobacterial lung disease in patients with cystic fibrosis (CF). There has been no previous investigation of possible differences between M. massiliense and M. abscessus infections in the setting of CF. METHODS We studied a prospective cohort of 16 M. massiliense and 27 M. abscessus lung infection cases with CF, with a mean follow-up of 6 years. RESULTS M. massiliense cases were younger than M. abscessus cases (mean age: 12.8 vs 17.1 years; p=0.02) at the time of the first mycobacterial isolation and also had lower body mass index values (mean: 16.4 vs 19.3 kg/m(2), p=0.002). All M. massiliense cases, except one, had negative BMI Z-score values at the time of the first mycobacterial isolation (11/12 vs 16/23 M. abscessus cases, p=0.04). Clarithromycin-based combination therapies led to mycobacterial eradication in 100% of M. massiliense cases but only in 27% of M. abscessus cases (p=0.009). CONCLUSION Our data show a particular link between M. massiliense and malnutrition specifically in CF patients. Unlike M. abscessus, the bacteriological response of M. massiliense to combination antibiotic therapies containing clarithromycin was excellent. Distinguishing between M. massiliense and M. abscessus has major clinical implications for CF patients.

In Vivo Evaluation of Antibiotic Activity Against Mycobacterium abscessus

BACKGROUND The prognosis of Mycobacterium abscessus infections is poor due to the lack of effective drug treatment. The objective of this study was to set up an animal model suitable to test antibiotic activity against M. abscessus. METHODS The following mouse strains were evaluated: Swiss, BALB/c, C57BL/6, nude, beige, A/J, and GKO. Antibiotic activity was tested for clarithromycin, amikacin, cefoxitin, tigecycline, and bedaquiline (TMC207). Finally, we evaluated the 3-drug combination clarithromycin, cefoxitin, and amikacin. RESULTS Nude and GKO mice fulfilled criteria for the model but only nude mice offered sufficient availability for large therapeutic experiments. Among the 3 drugs usually combined for treatment of M. abscessus infection, cefoxitin was the most active because it improved survival and reduced bacillary loads in spleen whereas clarithromycin and amikacin prevented death but had little impact on bacillary loads. The triple-drug combination was not more active than cefoxitin alone. Tigecycline displayed bactericidal activity whereas bedaquiline was almost inactive. CONCLUSIONS Nude mice are an adequate model for in vivo chemotherapy studies. Among tested drugs, cefoxitin and tigecycline showed promising in vivo activity against M. abscessus. The best drug combination remains to be determined.

Diagnostic Criteria of Urinary Tract Infection in Male Patients With Spinal Cord Injury

Background. The current diagnostic criteria of urinary tract infection (UTI) in male patients with spinal cord injury (SCI) are not clear. Methods. The authors studied 381 episodes of “symptomatic” UTI (209 participants) and 277 episodes of “asymptomatic” UTI (205 participants) in male SCI patients using intermittent catheterization. UTI was defined as a bacterial count ≥102 colony-forming units (cfu)/mL (American Paraplegia Society criterion). Univariate analysis and receiver operating characteristic (ROC) curve analysis were used to determine optimal cfu and white blood cell (WBC) thresholds. Results. The most prevalent clinical signs, alone or in combination, were cloudy and/or malodorous urine (51.4%), onset of urinary incontinence (51.2%), fatigue (41.7%), fever (30.7%), and increased spasticity (30.2%). Urine cfu and WBC levels in patients with only one sign, including fever, were not significantly higher than those in asymptomatic controls. WBC, but not cfu, levels increased significantly with the number of signs (P = .026). Univariate analysis and ROC curve analysis failed to identify cfu, WBC, or a combination of cfu and WBC count thresholds, allowing discrimination between the symptomatic and asymptomatic UTI groups. Conclusions. Clinical signs of UTI correlate poorly with the urine cfu and WBC levels in SCI patients, except for a positive relationship between WBC counts and the number of signs. Fever alone has no higher diagnostic value. There are no satisfactory cfu and WBC thresholds: thresholds more restrictive than the current American Paraplegia Society criteria provide higher specificity values but with equivalent loss of sensitivity.

Ruminococcus gnavus total hip arthroplasty infection in a 62-year-old man with ulcerative colitis

ABSTRACT We report the case of a total hip arthroplasty infection caused by Ruminococcus gnavus in a 62-year-old man with ulcerative colitis. The bacterium was perfectly identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry.