Variable-number tandem-repeat markers for typing Mycobacterium intracellulare strains isolated in humans.

BACKGROUND: Mycobacterium intracellulare, a species of the Mycobacterium avium complex, may be the cause of severe lung, lymphatic node, skin and bone/joint infections, as well as bacteriemia. The goal of this work was to identify Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat (MIRU-VNTR) markers and to study their variability in a collection of isolates of M. intracellulare collected in humans. We studied 61 isolates collected in humans between 2001 and 2008, as well as the reference strain, M. intracellulare ATCC 13950. RESULTS: We identified 45 MIRU-VNTR candidates, of which 17 corresponded to the MIRU-VNTR identified in the genome of M. intracellulare ATCC 13950. Among the 45 potential MIRU-VNTR, seven were selected for use in a MIRU-VNTR assay applied to our collection of isolates. Forty-four patterns were found by MIRU-VNTR typing and the discriminatory power of the assay was high with a Hunter-Gaston diversity index of 0.98. We do not have evidence of a particular distribution of MIRU-VNTR polymorphism according to clinical situation. CONCLUSIONS: Our results suggest that MIRU-VNTR typing could be used for molecular epidemiological studies applied to M. intracellulare.

Comparative in vitro activity of Meropenem, Imipenem and Piperacillin/tazobactam against 1071 clinical isolates using 2 different methods: a French multicentre study.

BACKGROUND: Meropenem is a carbapenem that has an excellent activity against many gram-positive and gram-negative aerobic, facultative, and anaerobic bacteria. The major objective of the present study was to assess the in vitro activity of meropenem compared to imipenem and piperacillin/tazobactam, against 1071 non-repetitive isolates collected from patients with bacteremia (55%), pneumonia (29%), peritonitis (12%) and wound infections (3%), in 15 French hospitals in 2006. The secondary aim of the study was to compare the results of routinely testings and those obtained by a referent laboratory. METHOD: Susceptibility testing and Minimum Inhibitory Concentrations (MICs) of meropenem, imipenem and piperacillin/tazobactam were determined locally by Etest method. Susceptibility to meropenem was confirmed at a central laboratory by disc diffusion method and MICs determined by agar dilution method for meropenem, imipenem and piperacillin/tazobactam. RESULTS: Cumulative susceptibility rates against Escherichia coli were, meropenem and imipenem: 100% and piperacillin/tazobactam: 90%. Against other Enterobacteriaceae, the rates were meropenem: 99%, imipenem: 98% and piperacillin/tazobactam: 90%. All Staphylococci, Streptococci and anaerobes were susceptible to the three antibiotics. Against non fermeters, meropenem was active on 84-94% of the strains, imipenem on 84-98% of the strains and piperacillin/tazobactam on 90-100% of the strains. CONCLUSIONS: Compared to imipenem, meropenem displays lower MICs against Enterobacteriaceae, Escherichia coli and Pseudomonas aeruginosa. Except for non fermenters, MICs90 of carbapenems were <4 mg/L. Piperacillin/tazobactam was less active against Enterobacteriaceae and Acinetobacter but not P. aeruginosa. Some discrepancies were noted between MICs determined by Etest accross centres and MICs determined by agar dilution method at the central laboratory. Discrepancies were more common for imipenem testing and more frequently related to a few centres. Overall MICs determined by Etest were in general higher (0.5 log to 1 log fold) than MICs by agar dilution.

CD23 mediates antimycobacterial activity of human macrophages.

Engagement of surface receptors contributes to the antimicrobial activity of human immune cells. We show here that infection of human monocyte-derived macrophages (MDM) with live Mycobacterium avium induced the expression of CD23 on their membrane. Subsequent cross-linking of surface CD23 by appropriate ligands induced a dose-dependent antibacterial activity of MDM and the elimination of most infected cells. The stimulation of inducible nitric oxide synthase-dependent generation of NO from MDM after CD23 activation played a major role during their anti-M. avium activity. CD23 activation also induced tumor necrosis factor alpha (TNF-alpha) production from MDM. Mycobacteria reduction was partially inhibited by the addition of neutralizing anti-TNF-alpha antibody to cell cultures without affecting NO levels, which suggested the role of this cytokine for optimal antimicrobial activity. Finally, interleukin-10, a Th2 cytokine known to downregulate CD23 pathway, is shown to decrease NO generation and mycobacteria elimination by macrophages. Therefore, (i) infection with M. avium promotes functional surface CD23 expression on human macrophages and (ii) subsequent signaling of this molecule contributes to the antimicrobial activity of these cells through an NO- and TNF-alpha-dependent pathway. This study reveals a new human immune response mechanism to counter mycobacterial infection involving CD23 and its related ligands.

Tsukamurella tyrosinosolvens--an unusual case report of bacteremic pneumonia after lung transplantation.

BACKGROUND: Lung transplant recipients have an increased risk for actinomycetales infection secondary to immunosuppressive regimen. CASE PRESENTATION: A case of pulmonary infection with bacteremia due to Tsukamurella tyrosinosolvens in a 54-year old man who underwent a double lung transplantation four years previously is presented. CONCLUSION: The identification by conventional biochemical assays was unsuccessful and hsp gene sequencing was used to identify Tsukamurella tyrosinosolvens.

Synthesis and antitubercular activity of ferrocenyl diaminoalcohols and diamines.

A total of 21 ferrocenyl and benzyl diaminoalcohols and diamines were synthesized and evaluated against Mycobacterium tuberculosis H37Rv. Interestingly, ferrocenyl diamines exhibit better activities than ferrocenyl diaminoalcohols.

Antimicrobial resistance data on 16,756 Streptococcus pneumoniae isolates in 1999: A Pan-Regional Multicenter Surveillance Study in France.

The rising prevalence of antibiotic-resistant Streptococcus pneumoniae is a phenomenon observed to different degrees around the world. The present national surveillance study report analyzes a total of 16,756 strains of S. pneumoniae collected across France in 1999. The overall prevalence of S. pneumoniae with decreased susceptibility to penicillin was 44%, to amoxicillin 26%, and to cefotaxime 17%. The proportion of high-level resistant strains to penicillin (MIC > 1 mg/L), amoxicillin and cefotaxime (MIC > 2 mg/L) remained low: 12.3%, 1.8%, and 0.4% respectively. Prevalence of resistance to other antibiotics was high: 53% to erythromycin, 41.7% to cotrimoxazole, 31.8% to tetracycline, and 24.6% to chloramphenicol. Prevalence of penicillin-resistant S. pneumoniae varied according to subject age and specimen source. It was higher in children (52.7%) than in adults (39.8%) and higher in strains isolated from middle ear fluid (63.6%) than from blood cultures (41.8%) in children. S. pneumoniae resistant to other antibiotics were more common in children than in adults, although figures showed geographical variations. Comparison with a previous study realized in 1997 in the same regions confirms a rising trend in the prevalence of resistant bacteria. Therefore, we conclude that prevalence of antibiotic-resistant S. pneumoniae in 1999 continued to rise in France, although strains with high-level resistance to penicillin remained stable.

Increase in primary drug resistance of Mycobacterium tuberculosis in younger birth cohorts in France.

BACKGROUND: Monitoring of primary drug resistance is of interest for long-term evaluation of the efficacy of a national tuberculosis program. The objective was to describe changes over time in primary drug resistance among new tuberculosis patients. METHODS: Stratified analysis by birth cohorts, region of birth, HIV-coinfection of data from 14,610 culture-positive new tuberculosis patients diagnosed by a network of university hospitals between 1995 and 2008. RESULTS: Half of the patients were foreign-born, and 9% HIV-coinfected. For foreign-born and French-born patients, there was an upward trend in resistance rates to streptomycin, isoniazid, and rifampicin from the oldest to the youngest cohorts. For a same age at tuberculosis diagnosis, the risk of isoniazid resistance was higher in younger cohorts, revealing a cohort effect. Among French-born patients, the only factor independently associated with primary resistance to streptomycin, or isoniazid was birth after 1950, and particularly after 1980. Risk of streptomycin resistance increased in youngest cohorts among European-born patients. HIV-coinfection was associated to rifampicin resistance among foreign-born and French-born patients, CONCLUSIONS: Theses results indicate that among French-born patients, isoniazid-resistant strains are currently circulating in younger patients that are more likely to be infected recently, and that among foreign-born patients, HIV-coinfection is a strong risk factor for primary resistance.

Synthesis and antimycobacterial activity of a series of ferrocenyl derivatives.

In this work we reported the synthesis and evaluation of Mycobacterium tuberculosis activities in vitro of a series of twenty five ferrocenyl derivatives: ferrocenyl amides derived from nicotinamide and pyrazinamide, ferrocenyl pyridinyl, quinolyl and acridinylhydrazones. In particular ferrocenyl acylhydrazones 7 and 8 and ferrocenylquinoxaline amide 57 showed interesting antimycobacterial activities.

Epidemiology and antimicrobial resistance of Streptococcus pneumoniae in France in 2007: data from the pneumococcus surveillance network.

Antimicrobial resistance of Streptococcus pneumoniae in France is closely monitored by the pneumococcus surveillance network, founded in 1995, which collects data from regional observatories (Observatoire Régionaux du Pneumocoque [ORP]). In 2007, 23 ORPs analyzed the antibiotic susceptibility of 5,302 isolates of S. pneumoniae recovered in France from cerebrospinal fluid, blood, middle ear fluid, and pleural fluid, as well as from adult respiratory samples. The study showed that 38.2% of the strains were nonsusceptible to penicillin, 19.3% nonsusceptible to amoxicillin, and 10.5% nonsusceptible to cefotaxime. The percentage of pneumococcus nonsusceptible to penicillin varied according to both the sample and the age of the patient (child/adult): blood (27.8%/32.5%), cerebrospinal fluid (33.7%/34.6%), middle ear fluid (60.2%/27.5%), and pleural fluid (50.0%/31.0%). Between 2003 and 2007, the frequency of penicillin resistance in invasive pneumococcal disease gradually decreased from 46.4% to 29.0% in children and from 43.8% to 32.7% in adults. This decrease coincided with the introduction of a seven-valent pneumococcal conjugate vaccine into immunization programs and with a general reduction in levels of antibiotic consumption in France.

Serotype distribution and antibiotic resistance of Streptococcus pneumoniae strains isolated from adults in France: evolution between 2001 and 2003.

Antibiotic-resistant Streptococcus pneumoniae (Sp) are described around the world. The present national surveillance study report analyzes more than 6000 Sp strains, isolated from adults across France in 2001 and 2003, from blood cultures (3086 in 2001 and 3164 in 2003), cerebrospinal fluid (respectively, 238 and 240), or middle ear fluid (respectively, 110 and 100). The proportion of isolates with reduced susceptibility to penicillin fell significantly between 2001 and 2003 from 46.5% to 43.9%. The proportion of high-level resistant strains to penicillin minimal inhibitory concentrations (MIC > 1 mg/L), amoxicillin, and cefotaxime (MIC > 2 mg/L) slightly decreased but remained low: 10.6%, 1.2%, and 0.2% in 2003. Resistance to other antibiotics (erythromycin, cotrimoxazole, tetracycline, and chloramphenicol) also decreased. Decrease in prevalence of penicillin-resistant Sp varied according to specimen source. The proportion of penicillin nonsusceptible pneumococci decreased in blood cultures and middle ear fluids between 2001 and 2003 but increased in cerebrospinal fluid (43.4% and 46.5%, respectively). Serotypes covered by the heptavalent vaccine accounted for 42.4% of all isolates recovered in 2001 and 46.1% in 2003. Prevalence of antibiotic-resistant Sp decreased in 2003 in France.

Synthesis and antimycobacterial activity of ferrocenyl ethambutol analogues and ferrocenyl diamines.

A new series of ferrocenyl diamino alcohols and diamines were synthesized and their inhibitory potencies were probed with Mycobacterium tuberculosis. Interestingly, ferrocenyl diamines 6a and b display significant activities against M. tuberculosis H37Rv.

Clinical and molecular analysis of extended-spectrum {beta}-lactamase-producing enterobacteria in the community setting.

During a previous survey, five extended-spectrum beta-lactamase (ESBL)-producing enterobacteria (ESBLE) (two Enterobacter aerogenes isolates expressing TEM-24 b, two Escherichia coli isolates expressing TEM-21 or TEM-24 b, and one Klebsiella pneumoniae isolate expressing SHV-4/TEM-15) responsible for urinary tract infections (UTIs) were found among 1,584 strains collected from community patients. The aim of the present study was to elucidate the route of emergence of these typically nosocomial organisms in the community. Thus, the files of the five patients were analyzed over at least a decade, and potentially related ESBLE from hospitals or clinics were examined. Their enzymes were characterized at a molecular level, and the strains were typed by amplified-primed PCR, enterobacterial repetitive intergenic consensus PCR, and restriction plasmid profile. All patients (C1 to C5) had risk factors for ESBLE acquisition, including past history of hospitalization (2.5 to 23 months before). Four (C1 and C3 to C5) had previously received antibiotics (concomitantly to 35 months earlier), two (C1 and C3) had indwelling urinary catheters and recurrent UTIs, and three (C2, C3, and C5) formerly experienced ESBLE-induced UTIs (2 to 11 months before). The same ESBLE and/or an identical or similar ESBL-encoding plasmid was identified in the hospital ward (C1 to C4) or in a clinic (C5) where the patients had previously resided. Patients C1 and C4, infected with different ESBLE carrying a closely related plasmid, were hospitalized in the same unit. Persistence of ESBLE over at least a 5-year period was demonstrated for patient C3. Thus, community-acquired UTIs in these patients likely resulted from nosocomially acquired ESBLE or an ESBL-encoding plasmid followed by a prolonged digestive carriage.

Global distribution of Mycobacterium tuberculosis spoligotypes.

We present a short summary of recent observations on the global distribution of the major clades of the Mycobacterium tuberculosis complex, the causative agent of tuberculosis. This global distribution was defined by data-mining of an international spoligotyping database, SpolDB3. This database contains 11708 patterns from as many clinical isolates originating from more than 90 countries. The 11708 spoligotypes were clustered into 813 shared types. A total of 1300 orphan patterns (clinical isolates showing a unique spoligotype) were also detected.

Snapshot of moving and expanding clones of Mycobacterium tuberculosis and their global distribution assessed by spoligotyping in an international study.

The present update on the global distribution of Mycobacterium tuberculosis complex spoligotypes provides both the octal and binary descriptions of the spoligotypes for M. tuberculosis complex, including Mycobacterium bovis, from >90 countries (13,008 patterns grouped into 813 shared types containing 11,708 isolates and 1,300 orphan patterns). A number of potential indices were developed to summarize the information on the biogeographical specificity of a given shared type, as well as its geographical spreading (matching code and spreading index, respectively). To facilitate the analysis of hundreds of spoligotypes each made up of a binary succession of 43 bits of information, a number of major and minor visual rules were also defined. A total of six major rules (A to F) with the precise description of the extra missing spacers (minor rules) were used to define 36 major clades (or families) of M. tuberculosis. Some major clades identified were the East African-Indian (EAI) clade, the Beijing clade, the Haarlem clade, the Latin American and Mediterranean (LAM) clade, the Central Asian (CAS) clade, a European clade of IS6110 low banders (X; highly prevalent in the United States and United Kingdom), and a widespread yet poorly defined clade (T). When the visual rules defined above were used for an automated labeling of the 813 shared types to define nine superfamilies of strains (Mycobacterium africanum, Beijing, M. bovis, EAI, CAS, T, Haarlem, X, and LAM), 96.9% of the shared types received a label, showing the potential for automated labeling of M. tuberculosis families in well-defined phylogeographical families. Intercontinental matches of shared types among eight continents and subcontinents (Africa, North America, Central America, South America, Europe, the Middle East and Central Asia, and the Far East) are analyzed and discussed.