Rothia spp. infective endocarditis: A systematic literature review.

OBJECTIVE: To describe the epidemiological, clinical, microbiological, and therapeutic features and outcomes of Rothia infective endocarditis (RIE) and extracardiac infections (ECRI). METHODS: We performed a systematic literature review of published cases of RIE and ECRI. RESULTS: After inclusion of a personal case report, 51 cases of RIE and 215 cases of ECRI were reported. Compared with ECRI patients, RIE patients were significantly more often males (80% versus 59%), intravenous drug users (IVDU) (20% versus 3%), immunocompetent (76% versus 31%), and infected with R. dentocariosa (55% versus 13%) but lacked significant differences with regard to median age (45 years [6-79]), rate of orodental abnormalities (33%), and six-month mortality (14%). Following microbiological documentation, RIE was most often treated with a beta-lactam antibiotic alone (39%) for a median duration of six weeks and required surgery in 39% of cases. CONCLUSION: RIE is rare and likely secondary to a dental portal of entry or cutaneous inoculation in IVDU. Its prognosis seems to be favorable.

Comparison of MALDI-ToF MS with the Rapidec Carba NP test for the detection of carbapenemase-producing Enterobacteriaceae.

Although carbapenemase-producing Enterobacteriaceae (CPE) have become a serious public health issue, their detection remains challenging. The aim of this study was to implement a test based on imipenem hydrolysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS), using 65 strains producing or not a carbapenemase. Then, we compared its performance to that of the Rapidec Carba NP test using 20 additional strains. The MS-based test effectively discriminated between CPE and other non-carbapenem-susceptible strains compared to the Rapidec Carba NP test (sensitivity 100% and 92%, specificity 94% and 92%, respectively). The MS-based test gave less difficulty in interpretation than the colorimetric Rapidec Carba NP test. MALDI-ToF gave a result in less than one hour and limited the use of expensive molecular assays. In conclusion, the hydrolysis test based on MALDI-ToF MS can detect clinically relevant CPE isolates in routine practice. This technology, also described to screen for carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii complex strains, also seems to be interesting in routine practice for these pathogens.

Biological cost of fosfomycin resistance in Escherichia coli in a murine model of urinary tract infection.

Prevalence of fosfomycin resistance in E. coli clinical isolates from UTIs remains very low. Our hypothesis was that fosfomycin resistance may be associated with a biological cost. Three groups of strains of E. coli belonging to the B2 phylogenetic group were used: clinical wild-type (WT) isolates, clinical multidrug-resistant isolates and in vitro fosfomycin-resistant derivatives from the uropathogen clinical strain E. coli CFT073. In each group fosfomycin-susceptible and -resistant isolates were compared. In vitro, we found a significantly decreased growth rate for fosfomycin-resistant strains as compared with susceptible strains in the WT group. In a murine model of ascending UTI, there was a significant reduction in infection rates with fosfomycin-resistant isolates as compared with susceptible ones, in all 3 study groups, ranging from 28 to 39% (P<0.03). All fosfomycin-susceptible clinical strains were virulent in vivo (13/13), while fosfomycin-resistant clinical strains were either virulent (2/7) or non-virulent (5/7) (P<0.002). This difference was not explained by the number of virulence factors or pathogenicity-associated islands. In conclusion, fosfomycin resistance appears to carry some biological cost in E. coli, which may explain in part the apparent paradox of the low prevalence of fosfomycin resistance despite a high rate of spontaneous mutants.

In vitro activity of josamycin against Streptococcus pyogenes isolated from patients with upper respiratory tract infections in France.

OBJECTIVES: The primary objective of our study was to obtain susceptibility data for josamycin against Streptococcus pyogenes isolated from patients presenting with upper respiratory tract infections in France. The secondary objective was to characterize the molecular mechanism of resistance in macrolide-resistant isolates. PATIENTS AND METHODS: MICs of erythromycin, clarithromycin, azithromycin, josamycin, and clindamycin were determined by the broth microdilution method. Resistance genes erm(B), erm(TR), and mef(A) were screened by PCR. RESULTS: The MIC50 and MIC90 of josamycin against 193 isolates of S. pyogenes were 0.12 and 0.25mg/L, respectively, with a resistance rate estimated at 4.7%. Resistance was due to the erm(B) gene whereas strains harboring erm(TR) or mef(A) remained susceptible. CONCLUSIONS: Josamycin was active against >95% of S. pyogenes isolated from patients with upper respiratory tract infections, and can be used as an alternative for the treatment of pharyngitis.

In vitro activity of new antimicrobial agents against glycopeptide-resistant Enterococcus faecium clinical isolates from France between 2006 and 2008.

OBJECTIVE: The aim of this study was to determine the in vitro activity of six new antimicrobial agents against glycopeptide-resistant enterococci (GRE) strains from France. METHODS: Sixty epidemiologically unrelated clinical isolates of Enterococcus faecium (vanA or vanB), received at the National Reference Centre for Enterococci (CNR-Enc) between 2006 and 2008, were studied. The MICs of the following antibiotics were determined by broth microdilution according to Antibiogram Committee of the French Society for Microbiology (CA-SFM) guidelines: quinupristin-dalfopristin (Q-D), linezolid (LZD), daptomycin (DPT), tigecycline (TGC), ceftobiprole (CFT), and telavancin (TLV). Strains were classified using clinical breakpoints recommended by the CA-SFM (Q-D, LZD, TGC), or the Clinical and Laboratory Standards Institute (DPT). RESULTS: All strains were susceptible to LZD and DPT (MIC(90), 4 and 2µg/ml, respectively) and only a single strain presented intermediate susceptibility to tigecycline (MIC(90), 0.25µg/ml). Thirty percent of strains were resistant to Q-D (MIC(90), 4µg/ml), and CFT was constantly inactive (MIC(90), 64µg/ml). Finally, TLV showed low-level MICs (MIC(90), 0.5µg/ml) against vanB-positive isolates but not against vanA-positive isolates (MIC(90), 8µg/ml). CONCLUSION: Although several antibiotics are still active against GRE, it is essential to maintain an active antimicrobial resistance surveillance for these microorganisms considered as a model of multidrug resistance with a potential to transfer resistance to other bacterial species (e.g. Staphylococcus aureus).

Macrolide resistance phenotypes and genotypes in French clinical isolates of Streptococcus pneumoniae. Observatoire de Normandie du Pneumocoque.

The aim of this study was to analyze the mechanisms of macrolide resistance in French clinical isolates of Streptococcus pneumoniae. A total of 838 strains of pneumococci were isolated in 1997 in Normandy, a region of western France, by 19 microbiology laboratories. Fifty-three percent had displayed diminished susceptibility to penicillin G and 50% were resistant to erythromycin. From this collection, 92 penicillin-intermediate or -resistant and 18 penicillin-susceptible strains resistant to erythromycin were studied. The presence of erm genes coding for ribosomal methylases and of mefE-like genes responsible for macrolide efflux was screened by a multiplex polymerase chain reaction and confirmed by DNA/DNA hybridization. Of the 110 strains studied, 108 were cross-resistant to erythromycin, spiramycin and clindamycin, including 105 strains containing ermB-related genes and three strains that contained a combination of ermB- and mefE-related genes. Two strains apparently susceptible to clindamycin but resistant to spiramycin also contained ermB-related genes. No strain was resistant to erythromycin alone or contained only a mef-like gene. Therefore, resistance to erythromycin is mostly related to ribosomal methylation in this region of France.