There is no standard method for the diagnosis of prosthetic joint infection (PJI). The contribution of 16S rRNA gene PCR sequencing on a routine basis remains to be defined. We performed a prospective multicenter study to assess the contributions of 16S rRNA gene assays in PJI diagnosis. Over a 2-year period, all patients suspected to have PJIs and a few uninfected patients undergoing primary arthroplasty (control group) were included.

h Although numerous perioperative samples and culture media are required to diagnose prosthetic joint infection (PJI), their exact number and types have not yet been definitely determined with a high level of proof. We conducted a prospective multicenter study to determine the minimal number of samples and culture media required for accurate diagnosis of PJI. Over a 2-year period, consecutive patients with clinical signs suggesting PJI were included, with five perioperative samples per patient. The bacteriological and PJI diagnosis criteria were assessed using a random selection of two, three, or four samples and compared with those obtained using the recommended five samples (references guidelines). The results obtained with two or three culture media were then compared with those obtained with five culture media for both criteria. The times-to-positivity of the different culture media were calculated. PJI was confirmed in 215/264 suspected cases, with a bacteriological criterion in 192 (89%). The PJI was monomicrobial (85%) or polymicrobial (15%). Percentages of agreement of 98.1% and 99.7%, respectively, for the bacteriological criterion and confirmed PJI diagnosis were obtained when four perioperative samples were considered. The highest percentages of agreement were obtained with the association of three culture media, a blood culture bottle, a chocolate agar plate, and Schaedler broth, incubated for 5, 7, and 14 days, respectively. This new procedure leads to significant cost saving. Our prospective multicenter study showed that four samples seeded on three culture media are sufficient for diagnosing PJI. There is still no standard definition of prosthetic joint infection (PJI). Although numerous perioperative samples are needed to diagnose PJI, their optimal number is not yet definitively known. In 1998, Atkins et al., using a mathematical model, demonstrated that five or six perioperative samples, with a cutoff of three or more culture-positive samples, are needed to diagnose PJI with high sensitivity and specificity (1). Recent guidelines still recommend that about five samples should be cultured for optimal diagnosis of PJI (2, 3). Since each tissue specimen is cultured on four to five culture media, a total of 20 to 25 culture media have to be analyzed per patient. The optimal duration of incubation for periprosthetic cultures was extended to 13 or 14 days, especially for Propionibacterium acnes recovery (4, 5). The implementation of 14-day culture incubation in combination with the use of multiple solid and liquid aerobic and anaerobic culture media makes the daily monitoring of PJI by the laboratory very complex, costly, and time-consuming. Moreover, the number of cases of PJI will continue to increase in the coming decades. Forecasts predict that by 2030, the demand for total hip and knee arthroplasties will grow to 4 million in the United States (6). A major economic effect is that device-associated costs are significantly higher than native bone and joint infections, as recently reported (7). Thi...

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Aminoglycosides are commonly used in the treatment of nosocomial pneumonia in association with beta-lactams. Unfortunately, penetration of intravenously administered aminoglycosides into the lung tissue remains low. In animal models, aerosolization of these drugs provides high lung concentrations and low serum levels. Three-hundred milligrams of tobramycin and 1 ml of 99mTc-DTPA were administered via a pneumatic nebulizer to five healthy volunteers and to five mechanically ventilated patients. Lung scintigraphy was then performed, and plasma and urine pharmacokinetics were studied. In a second group of patients undergoing thoracic surgery, 300 mg of tobramycin alone were administered in the same way; a fragment of healthy lung was then removed, and tobramycin was measured. In the first group, the scintigraphy showed radioactivity distribution in the whole lungs both in healthy volunteers and in ventilated patients. Urine samples contained 5.5% of the initial amount of tobramycin. The mean serum half-life of tobramycin was 8.96 h in healthy volunteers and 11.23 h in ventilated patients. In the second group, mean lung tissue concentrations were 5.5 and 3.61 micrograms/g, respectively, 4 and 12 h after nebulization, respectively. Aerosolization of tobramycin thus produced high lung concentrations and low serum levels.

The influence of hospital use of antibiotics other than cephalosporins and fluoroquinolones on extended-spectrum beta-lactamase (ESBL) resistance among Enterobacteriaceae is poorly known. Our objective was to explore the association between ESBL and hospital use of various classes of antibacterial agents. The relationship between monthly use of 19 classes of antibacterial agents and incidence of nosocomial ESBL-producing Enterobacteriaceae in a French hospital was studied between 2007 and 2013. Five antibiotic classes were significantly and independently associated with ESBL resistance. Uses of tetracyclines (link estimate ± SE, 0.0066 ± 0.0033), lincosamides (0.0093 ± 0.0029), and other antibacterial agents (0.0050 ± 0.0023) were associated with an increased incidence, while nitrofurantoin (-0.0188 ± 0.0062) and ticarcillin and piperacillin with or without enzyme inhibitor (-0.0078 ± 0.0031) were associated with a decreased incidence. In a multivariate model including 3rd- and 4th-generation cephalosporins, fluoroquinolones, amoxicillin, and amoxicillin-clavulanate, 3rd- and 4th-generation cephalosporins (0.0019 ± 0.0009) and fluoroquinolones (0.0020 ± 0.0008) were associated with an increased ESBL resistance, whereas amoxicillin and amoxicillin-clavulanate were not. Hospital use of tetracyclines and lincosamides may promote ESBL resistance in Enterobacteriaceae. Nitrofurantoin and ticarcillin and piperacillin with or without enzyme inhibitor should be considered as potential alternatives to broad-spectrum cephalosporins and fluoroquinolones to control the diffusion of ESBL resistance.