Henri Drugeon

Genetics and Expression of the Carbapenem-Hydrolyzing Oxacillinase Gene blaOXA-23 in Acinetobacter baumannii

ABSTRACT The genetic structures surrounding the plasmid-carried blaOXA-23 oxacillinase gene, encoding resistance to carbapenems, were studied in Acinetobacter baumannii. ISAba1 and the novel element ISAba4 were detected upstream of the blaOXA-23 gene, providing promoter sequences for its expression. These insertion elements were likely involved in transposition processes at the origin of acquisition of this β-lactamase gene.

Surgical-Site Infection After Cardiac Surgery: Incidence, Microbiology, and risk Factors

OBJECTIVEnTo identify risk factors associated with surgical-site infection according to the depth of infection, the cardiac procedure, and the National Nosocomial Infections Surveillance System risk index.nnnDESIGNnProspective survey conducted during a 12-month period.nnnSETTINGnA 48-bed cardiac surgical department in a teaching hospital.nnnPATIENTSnPatients admitted for cardiac surgery between February 2002 and January 2003.nnnRESULTSnSurgical-site infections were diagnosed in 3% of the patients (38 of 1,268). Of the 38 surgical-site infections, 20 were superficial incisional infections and 18 were mediastinitis for incidence rates of 1.6% and 1.4%, respectively. Cultures were positive in 28 cases and the most commonly isolated pathogen was Staphylococcus. A National Nosocomial Infections Surveillance System risk index score of 2 or greater was associated with a risk of surgical-site infection (relative risk, 2.4; P < .004). Heart transplantation, mechanical circulatory assistance, coronary artery bypass graft with the use of internal mammary artery, and reoperation for cardiac tamponade or pericard effusion were independent risk factors associated with surgical-site infection.nnnCONCLUSIONSnData surveillance using incidence rates stratified by cardiac procedure and type of infection is relevant to improving infection control efforts. Risk factors in patients who developed superficial infection were different from those in patients who developed mediastinitis. Coronary artery bypass graft using internal mammary artery was associated with a high risk of surgical-site infection, and independent factors such as reoperation for cardiac tamponade or pericard effusion increased the risk of infection.

Significance of Propionibacterium acnes-positive samples in spinal instrumentation.

Study Design. A retrospective study about Propionibacterium acnes infections after Cotrel–Dubousset (CD) instrumentation. Objectives. To analyze the significance of P. acnes-positive deep samples after CD. Summary of Background Data. The diagnosis of spinal infections to P. acnes after CD is difficult. Methods. Patients with revision surgery and at least 1 P. acnes-positive deep sample, between 2000 and 2006 were included. Group A had 1 revision surgery and group B had 2 successive revision surgeries, with P. acnes-positive deep samples. Group A was divided into 2 subgroups according to the peroperative macroscopic aspect, subgroup A1 with septic tissues, subgroup A2 without septic tissues. The biologic characteristics of the patients and the surgical and medical treatments were assessed. Results. Sixty-eight patients were included, 60 in group A (A1 = 33, A2 = 27) and 8 in group B. Group A: 26 patients had 1 or 2 P. acnes-positive samples and 34 had at least 3 P. acnes-positive samples. Histology showed chronic inflammatory changes. C-reactive protein value median rate was 42 (A1) and 5 mg/L (A2). Twenty-two patients had a complete implant removal (14 with antibiotics, A1 = 12, A2 = 2). Nine patients had a total implant replacement (7 with antibiotics). Twenty-two patients had a partial implant removal (17 with antibiotics, A1 = 5, A2 = 12). Seven A1 patients had an irrigation and debridement (6 with antibiotics). The evolution was favorable for 28 patients. Seven patients had a documented sepsis. Group B: during the first revision, 8 patients had a partial implant removal (2 with antibiotics); during the second revision, all patients received antibiotics 4 of whom had a total implant removal. The long-term evolution was favorable for 6 patients. Conclusion. P. acnes infection of spinal instrumentation is difficult to diagnose. Results of at least 4 deep sample cultures, histology, and C-reactive protein values must be compared to the peroperative macroscopic aspect.

Combination of Quinupristin-Dalfopristin and Gentamicin against Methicillin-Resistant Staphylococcus aureus: Experimental Rabbit Endocarditis Study

ABSTRACT The combination of quinupristin-dalfopristin (Q-D) and gentamicin was tested against two strains of gentamicin- and dalfopristin-susceptible methicillin-resistant Staphylococcus aureus (MRSA). One strain was susceptible to macrolides, lincosamides, and streptogramin B type antibiotics (MLSB), and the other was constitutively resistant to these antibiotics by virtue of the ermA gene. The checkerboard method and time-kill curves showed that the combination of Q-D and gentamicin was indifferent. A rabbit endocarditis model simulated the pharmacokinetics achieved in humans receiving intravenous injections of Q-D (7.5 mg/kg of body weight three times a day) and gentamicin (3 mg/kg once daily). For the MLSB-susceptible strain, a 4-day regimen reduced mean bacterial titers (MBT) in vegetations from 8.5 ± 0.8 log CFU/g (control group) to 4.1 ± 2.6 (gentamicin), 3.0 ± 0.9 (Q-D), and 2.6 ± 0.5 log CFU/g (Q-D plus gentamicin). For the strain constitutively resistant to MLSB, a 4-day regimen reduced MBT in vegetations from 8.7 ± 0.9 log CFU/g (control group) to 5.0 ± 2.2 (gentamicin), 5.2 ± 2.2 (Q-D), and 5.1 ± 2.4 log CFU/g (Q-D plus gentamicin). The differences between control and treatment groups were significant for both strains (P < 0.0001), although there was no significant difference between treatment groups. No resistant variant was isolated from vegetations, and no significant difference in MBT in vegetations of treatment groups after 1-day regimens was observed. This experimental study found no additive benefit in combining Q-D and gentamicin against dalfopristin- and gentamicin-susceptible MRSA.