Early switching from intravenous to oral antibiotic therapy in bone and joint infections associated with methicillin-susceptible Staphylococcus aureus bacteremia

OBJECTIVES

We aimed to evaluate the clinical outcomes of patients with bone and joint infection (BJI) associated with methicillin-susceptible Staphylococcus aureus bacteremia (MSSAB) treated with early oral switch to oral antibiotics (before day 14) versus later or no switch.

PATIENTS AND METHODS

We included all cases reported between January 2016 and December 2021 in the University Hospital of Reims.

RESULTS

Among 79 patients with BJI associated with MSSAB, 50.6% had an early switch to oral antibiotics, with median duration of intravenous antibiotics of 9 (IQR 6-11) days. The overall cure rate was 81% with follow-up of 6 months, and was 85.7% after excluding the 9 patients whose death was not related to BJI infection. Failure to control BJI did not differ between the two groups.

CONCLUSION

An early (before day 14) switch to oral antibiotics may be a safe therapeutic option in BJI associated with MSSAB.

Relationship between serotypes, disease characteristics and 30-day mortality in adults with invasive pneumococcal disease

PURPOSE

Invasive pneumococcal disease (IPD) is responsible for substantial mortality and morbidity worldwide. We aimed to identify host and bacterial factors associated with 30-day mortality in 18-year-old patients hospitalized with IPD in France from 2013 to 2015.

METHODS

This study analyzed data collected from consecutives IPD cases included in two parallel multi-center cohort studies: COMBAT study (280 patients with pneumococcal community-acquired bacterial meningitis) and SIIP study (491 patients with non-meningitis IPD). Factors associated with 30-day mortality were identified using logistic regression.

RESULTS

Among the 771 enrolled patients (median age 66 years, IQR [52.0-79.7]), 592/767 (77.2%) had at least one chronic disease. Patients with meningitis were younger (60.2 vs 70.9 years; p < 0.001) and had fewer chronic diseases than those with non-meningitis IPD (73.3% vs 79.4%; p = 0.05). Non-vaccine serotypes were more frequent in meningitis patients than in those with other IPD (36.1% vs 23.1%; p < 0.001). The overall 30-day mortality was 16.7% and patients with concurrent meningitis and extra-cerebral IPD had the highest 30-day mortality rate (26.5%). On multivariate analyses, older age, history of malignant solid tumor, meningeal IPD and serotypes previously identified with high mortality potential were independently associated with 30-day mortality. Of the serotypes with high mortality potential, 80% were included in licensed (PCV13 or PPV23) vaccines.

CONCLUSION

We observed an effect of both host factors and pneumococcal serotypes on 30-day mortality in IPD. This highlights the need for a focused strategy to vaccinate at-risk patients.

CLINICAL TRIAL

ClinicalTrial. Gov identification number: NCT01730690.

Bone and joint infections caused by Clostridium perfringens: a case series

The objective of this study was to evaluate antimicrobial therapy outcomes of bone and joint infections (BJI) caused by Clostridium perfringens. We investigated remission of symptoms and the absence of relapse or reinfection during follow-up. Among the 8 patients with C. perfringens BJI, the type of infection was early prosthesis infection (n = 2), osteosynthetic device infection (n = 4), and chronic osteomyeletis (n = 2). Clindamycin-rifampicin combination was given in 4 cases and metronidazole in 4 cases. The overall success rate was 87.5%. Among the 7 patients who completed antibiotic treatment, the success rate was 100%. The clindamycin-rifampicin combination appeared to be effective in patients with C. perfringens BJI.

Interaction of implant infection-related commensal bacteria with mesenchymal stem cells: a comparison between Cutibacterium acnes and Staphylococcus aureus

Staphylococcus aureus and Cutibacterium acnes are involved in several tissue infections and can encounter mesenchymal stem cells (MSCs) during their role in tissue regenerative process. C. acnes and S. aureus internalization by three types of MSCs derived from bone marrow, dental pulp and Wharton's jelly; and bacterial biofilm production were compared. Internalization rates ranged between 1.7-6.3% and 0.8-2.7% for C. acnes and S. aureus, respectively. While C. acnes strains exhibited limited cytotoxic effect on MSCs, S. aureus were more virulent with marked effect starting after only 3 h of interaction. Both bacteria were able to produce biofilms with respectively aggregated and monolayered structures for C. acnes and S. aureus. The increase in C. acnes capacity to develop biofilm following MSCs' internalization was not linked to the significant increase in number of live bacteria, except for bone marrow-MSCs/C. acnes CIP 53.117 with 79% live bacteria compared to the 36% before internalization. On the other hand, internalization of S. aureus had no impact on its ability to form biofilms composed mainly of living bacteria. The present study underlined the complexity of MSCs-bacteria cross-interaction and brought insights into understanding the MSCs behavior in response to bacterial infection in tissue regeneration context.

Clindamycin combination treatment for the treatment of bone and joint infections caused by clindamycin-susceptible, erythromycin-resistant Staphylococcus spp

The objective of this study was to evaluate the clinical outcomes and safety of clindamycin combination antibiotherapy for the treatment of erythromycin-resistant, lincosamide-susceptible bone and joint infections caused by Staphylococcus spp. Between January 2010 and September 2018, 46 patients with Staphylococcus spp. erythromycin-resistant, lincosamide-susceptible bone and joint infections were treated with clindamycin combination antibiotherapy for 6 to 12 weeks. The type of infection was prosthetic in 20 cases (43.5%), osteosynthetic device in 15 cases (32.6%), chronic osteomyelitis in 7 cases (15.2%), and arthritis in 4 cases (8.7%). The cure rate was 67.4% by intention to treat and 84.6% per protocol, with a median follow-up of 398 days (range 86-843). Only 2 relapses (5.1%) were observed in patients with chronic osteomyelitis; an acquired resistance to lincosamides developed in 1 case. Clindamycin combination therapy appears to be effective for the treatment of bone and joint infection caused by erythromycin-resistant, lincosamide-susceptible Staphylococcus spp.

Short duration of post-amputation antibiotic therapy in diabetic foot patients with total resection of osteomyelitis

BACKGROUND

Short duration of post-amputation antibiotic therapy (2-5 days) is recommended in patients with diabetic foot osteomyelitis after total resection of infected bone tissue.

OBJECTIVE

To evaluate the long-term effectiveness of short-duration post-amputation antibiotic therapy in diabetic patients with total resection of osteomyelitis assessed by sterile bone bacteriological samples obtained from the resection margin.

METHODS

The endpoint was the absence of osteomyelitis relapse at 6 months, defined as recurrence of osteomyelitis with the need for surgical revision and/or new bone antibiotic therapy.

RESULTS

Among 15 patients included, 12 (80%) were cured without recurrence of osteomyelitis at 6 months, with a mean duration of antibiotic therapy of 8.3±5.9 days post surgery. This result is comparable to literature data, while all of them reported longer duration of antibiotic therapy and/or shorter follow-up.

CONCLUSION

Short duration of post-amputation antibiotic therapy in diabetic patients with sterile bacteriological samples obtained from resection margin seems effective.

Infective Endocarditis Related to Unusual Microorganisms: A Prospective Population-Based Study

Background

Increased access to heart valves through early surgery and progress in molecular microbiology have reduced the proportion of infective endocarditis (IE) with no microbiological documentation and increased the proportion of IE associated with unusual microorganisms.

Methods

We performed an ancillary study of a large prospective population-based survey on IE. Unusual-microorganism IE was defined as definite IE (Duke-Li criteria) due to microorganisms other than streptococci, staphylococci, or enterococci.

Results

Of 471 cases of documented IE, 46 (9.8%) were due to unusal microorganisms; the following were involved in >1 case: Candida albicans (n = 4), Cutibacterium acnes (n = 4), Pseudomonas aeruginosa (n = 3), Cardiobacterium hominis (n = 3), and Coxiella burnetii (n = 2). Cases were documented with blood cultures (n = 37, 80.4%), heart valve polymerase chain reaction (PCR; n = 5), heart valve culture (n = 2), PCR on vertebral biopsy (n = 1), or serology (n = 1). As compared with IE due to staphylococci, streptococci, or enterococci (n = 420), IE due to unusual microorganisms occurred more frequently in patients with previously known heart disease (69.0% vs 44.3%; P = .002), prosthetic valve (40.5% vs 18.1%; P = .0006), longer duration of fever (mean, 35.1 ± 46.8 days vs 12.5 ± 17.8; P = .003), and who were more often nosocomial (38.1% vs 20.2%; P = .02).

Conclusions

In this population-based study, 9.8% of IE cases were due to unusual microorganisms, with a predominance of anaerobes, yeast, and gram-negative bacilli. As compared with IE related to staphylococci, streptococci, or enterococci, IE cases related to unusual microorganisms were associated with previously known heart disease, prosthetic valve, longer duration of fever, and nosocomial acquisition.

Trial registration

ORCID 0000-0003-3617-5411

Treatment of bone and joint infections caused by Enterobacter cloacae with a fluoroquinolone-cotrimoxazole combination

Although the frequency of bone and joint infections caused by Enterobacter spp. is increasing, studies regarding the optimal antibiotic therapy are scarce. The objective of this retrospective study was to assess the clinical outcomes and safety of a fluoroquinolone-cotrimoxazole combination for the treatment of bone and joint infections caused by Enterobacter cloacae. Between 2010 and 2017, 30 patients with bone and joint infections caused by E. cloacae were treated with a fluoroquinolone-cotrimoxazole combination for 8-12 weeks. There were 26 cases (87%) of infection of an internal fixation device, two cases (6.6%) of pseudarthrosis with chronic osteomyelitis, and two cases (6.6%) of infection of knee and ankle prosthetic devices. The cure rate of the fluoroquinolone-cotrimoxazole combination was 80% by intention-to-treat analysis, with a mean follow-up of 29.3 ± 19.1 months. The fluoroquinolone-cotrimoxazole combination for 8-12 weeks is effective for the treatment of bone and joint infections caused by E. cloacae.

Staphylococcus aureus CC30 Lineage and Absence of sed,j,r-Harboring Plasmid Predict Embolism in Infective Endocarditis

Staphylococcus aureus induces severe infective endocarditis (IE) where embolic complications are a major cause of death. Risk factors for embolism have been reported such as a younger age or larger IE vegetations, while methicillin resistance conferred by the mecA gene appeared as a protective factor. It is unclear, however, whether embolism is influenced by other S. aureus characteristics such as clonal complex (CC) or virulence pattern. We examined clinical and microbiological predictors of embolism in a prospective multicentric cohort of 98 French patients with monomicrobial S. aureus IE. The genomic contents of causative isolates were characterized using DNA array. To preserve statistical power, genotypic predictors were restricted to CC, secreted virulence factors and virulence regulators. Multivariate regularized logistic regression identified three independent predictors of embolism. Patients at higher risk were younger than the cohort median age of 62.5 y (adjusted odds ratio [OR] 0.14; 95% confidence interval [CI] 0.05-0.36). S. aureus characteristics predicting embolism were a CC30 genetic background (adjusted OR 9.734; 95% CI 1.53-192.8) and the absence of pIB485-like plasmid-borne enterotoxin-encoding genes sed, sej, and ser (sedjr; adjusted OR 0.07; 95% CI 0.004-0.457). CC30 S. aureus has been repeatedly reported to exhibit enhanced fitness in bloodstream infections, which might impact its ability to cause embolism. sedjr-encoded enterotoxins, whose superantigenic activity is unlikely to protect against embolism, possibly acted as a proxy to others genes of the pIB485-like plasmid found in genetically unrelated isolates from mostly embolism-free patients. mecA did not independently predict embolism but was strongly associated with sedjr. This mecA-sedjr association might have driven previous reports of a negative association of mecA and embolism. Collectively, our results suggest that the influence of S. aureus genotypic features on the risk of embolism may be stronger than previously suspected and independent of clinical risk factors.

Detection of different classes of carbapenemases: Adaptation and assessment of a phenotypic method applied to Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and proposal of a new algorithm

A new phenotypic method for detecting carbapenemases has been adapted (assembling of two MAST® kits, including one that contains faropenem to which a temocillin disk has been added) then assessed using 101 bacterial strains (Enterobacteriaceae with assays on Pseudomonas aeruginosa and Acinetobacter baumannii) including 62 which produce genetically identified carbapenemases. Concerning Carbapenemase-Producing Enterobacteriaceae (CPE), there is 100% sensitivity for Klebsiella pneumoniae carbapenemase (KPC, Ambler class A) and OXA-48 (Ambler class D), and 91% for metallo-beta-lactamase (MBL, Ambler class B), with a 97% sensitivity for all carbapenemases, with a specificity of 100%. The test is also efficient for detecting Pseudomonas aeruginosa carbapenemases (sensitivity between 82 and 100% and 100% specificity). The major innovation is the combined use of faropenem and temocillin for reliable detection (excellent performance with 100% sensitivity and specificity) of OXA-48. This study has led to the development of a new algorithm to detect the different classes of carbapenemases, for first-line diagnosis, by combining this modified MAST® test with immunochromatographic methods and molecular biology techniques.

Prognostic factors associated with 30-day in-hospital mortality in coagulase-negative Staphylococcus bacteraemia: no impact of vancomycin minimum inhibitory concentration

BACKGROUND

The impact of a minimum inhibitory concentration (MIC) of vancomycin ≥2 mg/L on mortality and the potential benefit of new antistaphylococcal treatments in coagulase-negative Staphylococcus (CoNS) bacteraemia remain unknown. We assessed the impact of vancomycin MIC on 30-day in-hospital mortality and identified factors independently associated with 30-day in-hospital mortality.

METHODS

All patients presenting significant CoNS bacteraemia in the university hospital of Reims, between 01 January 2008 and 31 December 2012, were included. Data were retrospectively extracted from the patient records. Vancomycin MIC was assessed using the E-test method, and antimicrobial susceptibility testing was performed in accordance with the recommendations of the Antibiogram Committee of the French Microbiology Society. Cox's Proportional Hazards model was used for multivariate analysis.

RESULTS

Two hundred and sixty-nine patients (mean age 61.2 ± 15.7 years) were included. Foreign material was present in 92% of patients and 78.4% of isolated methicillin-resistant strains had vancomycin MIC ≥2 mg/l. Thirty-day in-hospital mortality was 16%. There was no association between vancomycin MIC ≥2 mg/l and 30-day in-hospital mortality (adjusted Hazard Ratio (aHR) = .80, 95% confidence interval (95%CI) [.30-2.19], p = .67). Factors independently associated with 30-day in-hospital mortality were age ≥75 vs. ≤60 years (aHR =3.72, 95%CI [1.39-9.97], p = .009), absence of active antibiotic treatment (aHR =5.52, 95%CI [1.13-26.87], p = .03) and acute renal failure (aHR =4.45, 95%CI [2.08-9.56], p < .0001). Removal of an infected device had a protective effect against 30-day in-hospital mortality (aHR = .23, 95%CI [.11-.48], p < .0001).

CONCLUSIONS

These results suggest that CoNS bacteraemia should be managed by removal of the infected device and antibiotic treatment such as vancomycin.

Knowledge of antibiotics and antibiotic resistance in patients followed by family physicians

OBJECTIVE

We aimed to evaluate factors associated with knowledge of antibiotics and drug resistance.

METHODS

A questionnaire was handed out by 14 family physicians to their patients between December 20, 2014 and April 20, 2015 in Rethel (North-East of France). We conducted a cross-sectional study using a logistical regression model to assess factors associated with antibiotic knowledge. Three criteria were used to assess that knowledge.

RESULTS

Overall, 293 questionnaires were analysed; 48% of patients had received antibiotics in the previous 12 months. Only 44% and 26% gave a correct answer for the statements "Antibiotics are effective against bacteria and ineffective against viruses" and "Antibiotic resistance decreases if the antibiotic use decreases", respectively. Characteristics such as female sex, age>30 years, high level of education, high professional categories, and having received antibiotic information by the media were associated with high level of knowledge about antibiotics and/or antibiotic resistance. In contrast, having received antibiotic information from family physicians was not associated with good knowledge.

CONCLUSION

Although media awareness campaigns had an independent impact on a higher public knowledge of antibiotics, the overall public knowledge remains low. It would be necessary to strengthen antibiotic campaigns with clearer information on the relation between the excessive use of antibiotics and the increased risk of antibiotic resistance. Family physicians should be more involved to improve antibiotic knowledge among target groups such as men, young patients, and people from a poor social and cultural background.

Symptomatic and Asymptomatic Neurological Complications of Infective Endocarditis: Impact on Surgical Management and Prognosis

Objectives

Symptomatic neurological complications (NC) are a major cause of mortality in infective endocarditis (IE) but the impact of asymptomatic complications is unknown. We aimed to assess the impact of asymptomatic NC (AsNC) on the management and prognosis of IE.

Methods

From the database of cases collected for a population-based study on IE, we selected 283 patients with definite left-sided IE who had undergone at least one neuroimaging procedure (cerebral CT scan and/or MRI) performed as part of initial evaluation.

Results

Among those 283 patients, 100 had symptomatic neurological complications (SNC) prior to the investigation, 35 had an asymptomatic neurological complications (AsNC), and 148 had a normal cerebral imaging (NoNC). The rate of valve surgery was 43% in the 100 patients with SNC, 77% in the 35 with AsNC, and 54% in the 148 with NoNC (p<0.001). In-hospital mortality was 42% in patients with SNC, 8.6% in patients with AsNC, and 16.9% in patients with NoNC (p<0.001). Among the 135 patients with NC, 95 had an indication for valve surgery (71%), which was performed in 70 of them (mortality 20%) and not performed in 25 (mortality 68%). In a multivariate adjusted analysis of the 135 patients with NC, age, renal failure, septic shock, and IE caused by S. aureus were independently associated with in-hospital and 1-year mortality. In addition SNC was an independent predictor of 1-year mortality.

Conclusions

The presence of NC was associated with a poorer prognosis when symptomatic. Patients with AsNC had the highest rate of valve surgery and the lowest mortality rate, which suggests a protective role of surgery guided by systematic neuroimaging results.

Fluoroquinolone Resistance Mechanisms and population structure of Enterobacter cloacae non-susceptible to Ertapenem in North-Eastern France

Fluoroquinolone (FQ) agents are a potential resort to treat infection due to Enterobacteriaceae producing extended spectrum β-lactamase and susceptible to FQ. In a context of increase of non-susceptibility to carbapenems among Enterobacteriaceae, we characterized FQ resistance mechanisms in 75 Enterobacter cloacae isolates non-susceptible to ertapenem in North-Eastern France in 2012 and describe the population structure by pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Among them, 14.7% (12/75) carried a carbapenemase-encoding gene. Except one isolate producing VIM-1, the carbapenemase-producing isolates carried the well-known IncL/M pOXA48a plasmid. Most of the isolates (59/75) harbored at least a FQ-R determinant. qnr genes were predominant (40%, 30/75). The MLST study revealed that E. cloacae isolates’ clonality was wide [24 different sequence types (STs)]. The more widespread STs were ST74, ST101, ST110, ST114, and ST133. Carbapenem MICs were higher for E. cloacae ST74 than for other E. cloacae isolates. Plasmid-mediated quinolone resistance determinants were more often observed in E. cloacae ST74 isolates. These findings showed that (i) pOXA-48a is spreading in North-Eastern France, (ii) qnr is preponderant in E. cloacae, (iii) E. cloacae comprised a large amount of lineages spreading in North-Eastern France, and (iv) FQ as an alternative to β-lactams to treat ertapenem non-susceptible Enterobacteriaceae are compromised.

Decline in antibiotic resistance and changes in the serotype distribution of Streptococcus pneumoniae isolates from children with acute otitis media; a 2001-2011 survey by the French Pneumococcal Network

Streptococcus pneumoniae is an important cause of acute otitis media (AOM). The aim of this study was to evaluate trends in antibiotic resistance and circulating serotypes of pneumococci isolated from middle ear fluid of French children with AOM during the period 2001-2011, before and after the introduction of the PCV-7 (2003) and PCV-13 (2010) vaccines. Between 2001 and 2011 the French pneumococcal surveillance network analysed the antibiotic susceptibility of 6683 S. pneumoniae isolated from children with AOM, of which 1569 were serotyped. We observed a significant overall increase in antibiotic susceptibility. Respective resistance (I+R) rates in 2001 and 2011 were 76.9% and 57.3% for penicillin, 43.0% and 29.8% for amoxicillin, and 28.6% and 13.0% for cefotaxime. We also found a marked reduction in vaccine serotypes after PCV-7 implementation, from 63.0% in 2001 to 13.2% in 2011, while the incidence of the additional six serotypes included in PCV-13 increased during the same period, with a particularly high proportion of 19A isolates. The proportion of some non-PCV-13 serotypes also increased between 2001 and 2011, especially 15A and 23A. Before PCV-7 implementation, most (70.8%) penicillin non-susceptible pneumococci belonged to PCV-7 serotypes, whereas in 2011, 56.8% of penicillin non-susceptible pneumococci belonged to serotype 19A. Between 2001 and 2011, antibiotic resistance among pneumococci responsible for AOM in France fell markedly, and PCV-7 serotypes were replaced by non-PCV-7 serotypes, especially 19A. We are continuing to assess the impact of PCV-13, introduced in France in 2010, on pneumococcal serotype circulation and antibiotic resistance.

Mobile insertion cassette elements found in small non-transmissible plasmids in Proteeae may explain qnrD mobilization

qnrD is a plasmid mediated quinolone resistance gene from unknown origin, recently described in Enterobacteriaceae. It encodes a pentapeptide repeat protein 36-60% different from the other Qnr (A, B, C, S and VC). Since most qnrD-positive strains were described as strains belonging to Proteus or Providencia genera, we hypothesized that qnrD originated in Proteeae before disseminating to other enterobacterial species. We screened 317 strains of Proteeae for qnrD and its genetic support by PCR. For all the seven qnrD-positive strains (4 Proteus mirabilis, 1 Proteus vulgaris and 2 Providencia rettgeri) the gene was carried onto a small non-transmissible plasmid, contrarily to other qnr genes that are usually carried onto large multi-resistant plasmids. Nucleotide sequences of the qnrD-bearing plasmids were 96% identical. Plasmids contained 3 ORFs apart from qnrD and belonged to an undescribed incompatibility group. Only one plasmid, in P. vulgaris, was slightly different with a 1,568-bp insertion between qnrD and its promoter, leading to absence of quinolone resistance. We sought for similar plasmids in 15 reference strains of Proteeae, but which were tested negative for qnrD, and found a 48% identical plasmid (pVERM) in Providencia vermicola. In order to explain how qnrD could have been inserted into such native plasmid, we sought for gene mobilization structures. qnrD was found to be located within a mobile insertion cassette (mic) element which sequences are similar to one mic also found in pVERM. Our conclusions are that (i) the small non-transmissible qnrD-plasmids described here may result from the recombination between an as-yet-unknown progenitor of qnrD and pVERM, (ii) these plasmids are maintained in Proteeae being a qnrD reservoir (iii) the mic element may explain qnrD mobilization from non-transmissible plasmids to mobilizable or conjugative plasmids from other Enterobacteriaceae, (iv) they can recombined with larger multiresistant plasmids conjugated in Proteeae.

[Is it possible to detect Staphylococcus aureus colonization or bacteriuria before orthopedic surgery hospitalization?]

AIM OF THE STUDY

Evaluate the feasibility of Staphylococcus aureus nasal colonization and bacteriuria screening in outpatients before realizing a decolonization treatment in S. aureus carriers and a bacteriuria treatment before hospitalization.

METHODS

All patients undergoing hip, knee or back surgery in which prosthesis were implanted between October 2007 until the end of June 2008 were included. Microbiological studies were performed before hospitalization. Notice for S. aureus decolonization regimen was delivered to each patient and to the general practitioner only if the patient had nasal carriage.

RESULTS

Only 91.2% (240/263) of patients had microbiological results. Prevalence of S. aureus colonization was 21.4% (48 positives/224). Three patients were colonized with methicillin-resistant staphylococci. Decolonization regimen was applied before surgery to 70.8% (n=34) of the colonized patients. Among the patients, 8.9% (20/225) had bacteriuria, Escherichia coli being the most frequent micro-organism (n=16).

CONCLUSION

Preoperative search and management of S. aureus colonization and of bacteriuria in outpatients is possible. Monitoring record must be performed by a member of the hospital staff.

[Real-time PCR for fast detection of plasmid-mediated qnr genes in extended spectrum beta-lactamase producing Enterobacteriaceae]

AIM OF THE STUDY

To develop a fast and reliable real time PCR technique for detecting plasmid-mediated quinolone resistance genes qnrA, qnrB and qnrS.

METHODS

A real-time PCR assay using SYBR Green I and Roche LightCycler(®) was developed to detect qnr genes. Detection of qnr genes was based on comparison of melting temperature differences with a positive control of each qnr genes. This assay was performed to study 138 isolates collected from diagnostic and screening samples in the Champagne-Ardenne region in 2004 (France).

RESULTS

In optimized conditions, the three positive controls tested alone and with isolates confirmed the specificity of the PCR primers. Each PCR assay was able to test 30 strains in 60min for 1 qnr gene. Out of 138 isolates screened, 3.6 % isolates were positive for a qnrA1, 1.5 % for qnrS1 and no qnrB-like gene. Prevalence of qnr determinants was 5 % and reached 9.5 % in clinical isolates.

CONCLUSION

Real-time PCR is a fast and reliable technique for screening of qnr-positive strains. This study shows a relatively high prevalence of qnr determinants (5 %) among ESBL-producing Enterobacteriaceae.

Incidence of class A extended-spectrum -lactamases in Champagne-Ardenne (France): a 1 year prospective study

OBJECTIVES

To assess the frequency and diversity of extended spectrum beta-lactamases (ESBLs) in the Champagne-Ardenne region France, and to identify genetic elements associated with the bla(CTX-M) genes.

METHODS

During 2004, all the non-duplicate isolates of Pseudomonas aeruginosa and Acinetobacter baumannii resistant to ceftazidime and of Enterobacteriaceae intermediate or resistant to ceftazidime and/or cefotaxime, screening samples excluded, were collected in 10 public hospitals and 3 private clinics. bla genes were sequenced and bla(CTX-M) environment characterized by PCR mapping.

RESULTS

In Enterobacteriaceae (138/21 861; 0.6%), ESBLs were predominantly TEM-24 (n = 52; 37.7%) and CTX-M-15 (n = 37; 26.8%). Three new enzymes were identified, CTX-M-61 (CTX-M-1 group), TEM- and SHV-type. A. baumannii (n = 5) produced VEB-1 and P. aeruginosa (n = 2) SHV-2a. ISEcp1 was detected in 22/27 strains, disrupted in 7 of them. The IS903-like element was downstream of bla(CTX-M-14) and bla(CTX-M-16). ISCR1 was found upstream of bla(CTX-M-2) and bla(CTX-M-9), and ISCR1 and bla(CTX-M-2) were located on a sul1-type class 1 integron. In comparison with 2001-02, ESBL distribution among Enterobacteriaceae showed an increase in CTX-M-type (44.9% vs 3.7% P < 10(-7)) due to Escherichia coli CTX-M-15 and to the almost total disappearance of TEM-3 (0.9% vs 51.2%). E. coli was the most frequent species (50.0% vs 5.1% in 1998) despite a similar prevalence to that in 1998 (0.5% vs 0.2%).

CONCLUSIONS

A careful detection of bla(CTX-M)-type spread to other species would help to anticipate clonal endemics such as those observed in Enterobacter aerogenes TEM-24.

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.

Intérêt pharmacodynamique de la perfusion continue vs l'administration intermittente de ceftazidime dans les pneumonies nosocomiales sévères

GOAL OF THE STUDY

It is well known today that the main determinant of beta-lactam antibiotics efficacy is the duration of the time that concentrations remain in excess of the minimum inhibitory concentration (MIC) of susceptible organism over the course of therapy. This prospective study aimed to evaluate the efficacy, in term of pharmacodynamic profile, of continuous infusion versus intermittent administration of ceftazidime in intensive care unit patients with severe nosocomial pneumonia.

PATIENTS AND METHODS

16 patients under mechanical ventilation with nosocomial pneumonia were randomised to receive either 60 mg/kg/day ceftazidime by constant rate infusion following a 20 mg/kg loading dose (Group A) or 20 mg/kg every 8 hour by intravenous bolus injection (Group B). In both groups, serial blood samples were collected during 48 hours (12 and 18 samples in Group A and B, respectively) after the start of drug administration. Plasma concentrations of ceftazidime were measured by high performance liquid chromatography. Based on our local bacteriological conditions, the pharmacodynamic profile of ceftazidime was assessed as the duration of time the plasma concentration remained above a desired target concentration of 20 mg/l for each regimen.

RESULTS

The mean time (expressed as a percentage) for which plasma ceftazidime concentrations were above 20 mg/l was 100% for the continuous infusion group (Group A) and 56+/-33% for the intermittent administration group (Group B).

CONCLUSION

These findings show that ceftazidime administered by continuous infusion in critically ill patients under mechanical ventilation with nosocomial pneumonia appears to substantially improve the pharmacodynamic profile of this beta-lactam compared to the intermittent regimen.

[Infection on foreign material: bacterial colonization of ureteral endoprostheses]

Infection on foreign body: bacterial colonization of ureteric stents. The most frequent cause of the early removal of ureteric endoprostheses (double J) is generally due to bacterial colonization. In order to prevent or to restrict the prosthesis colonization, it is necessary to understand the major steps and the factors influencing the colonization. This is the reason why we aimed to extract the most relevant parameters influencing the bacterial colonization from the observations made in vivo thanks to in vitro analyses. We have studied in vivo the relationship between the bacterial colonization of the endoprostheses, the urinary infections and the antibiotherapy. In vitro, we have defined the conditions promoting the primary adhesion of the most frequently isolated bacteria on endoprostheses. Surface properties of bacteria and materials have been compared to:--the bacterial count of infected double J samples with respect to bacterial species,--the bacterial count of the infected samples with respect to pH and Ca2+, Mg2+ concentration. The results show a great variability of the biomaterial surface properties which could be optimized, the fact that the urinary medium acidification could lower the bacterial adhesion and the ambiguous role of Ca2+ and Mg2+ ions which is discussed in this paper. In the case of in vivo analyses, the conflicting results between leukocyturia and bacteriuria lead to the detection of the bacterial colonization under antibiotic treatment. The characterized urinary infection must warn the risk of pyelonephritis.

[Current role of coagulase-negative staphylococci in urology]

Coagulase-negative Staphylococci (CNS), considered for many years to be commensal bacteria of the skin are now recognized as major agents of nosocomial infection. Bacterial factors (increased resistance), host factors (immune status) and multiplication of the portals of entry (presence of foreign material) have contributed to the increased incidence of nosocomial infections. The importance of the role of NCS in urology is due to their great capacity to colonize catheters and most prostheses. The particular organization of these bacteria into a conglomerate called biofilm is responsible for prosthetic infections, which can impair renal function and can sometimes be life-threatening. The authors review the current increase of the number of CNS isolated in urology departments and describe the various therapeutic strategies that can be proposed to eradicate these bacteria.

[In vivo and in vitro analysis of the ability of urinary catheter to microbial colonization]

Bacterial adhesion to biomaterials is a complex phenomenon involving numerous factors. The ability to reduce urinary catheters infections simply by general hygiene and asepsis is low: an ascending colonization cannot be avoided. This will lead to a clinical infection only if several factors favour the bacterial adhesion or the bacterial coaggregation and the feeding of the bacterial biofilm. Among the many factors involved in bacterial adhesion, we focused in this paper on the physical parameters of surface hydrophobicity of the urinary catheters (Van der Waals and acido-basic forces) and the surface hydrophobicity of the bacteria (BATH and zeta potential). We also compared scanning electron microscopy (SEM) of in vivo and in vitro infected urinary catheters. We provided evidence that the more hydrophobic the bacteria, the more they are able to colonize hydrophobic materials, whereas hydrophilic cells are able to colonize hydrophilic materials more easily. Some biomaterials were found to display an irregular texture of hydrophobic and hydrophilic areas: they favour both types of adhesion. Moreover the divalent cations (MgII) drastically increased the bacterial coaggregation and favour bacterial growth within the biofilm. Finally, an increase in urinary pH and ionic strength increases the colonization risk. Consequently, choice of urinary catheter biomaterials is essential as patient hygiene and diet in order to avoid clinical infections.