The value of suction drainage fluid culture during aseptic and septic orthopedic surgery: a prospective study of 901 patients.

There are no guidelines on the value of suction drainage fluid culture (SDC), and it is difficult to determine whether the organisms cultured from suction drainage fluid samples are pathogenic or simply contaminants. We performed 2989 cultures of suction drainage fluid samples obtained, during a 1-year period, from 901 patients who underwent aseptic or septic orthopedic surgery (946 operations). The culture results were analyzed to evaluate their ability to detect postoperative infection after aseptic operations or to detect either a persistent or new episode of sepsis in patients known to have infection. For aseptic operations, the sensitivity of SDC was 25%, the specificity was 99%, the positive predictive value was 25%, and the negative predictive value was 99%. For septic operations, the sensitivity of SDC was 81%, the specificity was 96%, the positive predictive value was 87%, and the negative predictive value was 94%. We conclude that, for aseptic orthopedic surgery, SDC is not useful in detecting postoperative infection. However, for septic orthopedic surgery, it is of clinical importance.

Outpatient parenteral antimicrobial therapy (OPAT) for the treatment of osteomyelitis: evaluation of efficacy, tolerance and cost.

OBJECTIVES: To evaluate the feasibility, efficacy, and cost of outpatient parenteral antimicrobial therapy (OPAT) in the treatment of osteomyelitis. SUBJECTS: 39 patients with an osteomyelitis requiring parenterally administered antibiotics for more than 4 weeks, and able to receive antibiotics at home. METHODS: All patients had a totally implanted catheter. Antibiotics were administered by continuous infusion using a portable elastomeric infusion system, which was changed every day by the patient or by the home-care nurse. Laboratory monitoring and surveillance were performed weekly. Clinical efficacy, adverse effects and quality of life were recorded. RESULTS: The most commonly used antibiotics were vancomycin (51%) and beta-lactam (44%) antibiotics. Thirty patients were available for follow-up for a minimum of 12 months after completion of therapy. Twenty-eight (93%) were considered cured of their infection with a mean of 24 +/- 4 months after completion of antibiotic therapy. Adverse effects among the study patients were rare. The 39 patients in our OPAT programme resulted in a potential saving of US $1 873 885 relative to conventional therapy. CONCLUSION: OPAT is practicable and effective and may be the best alternative treatment for patients suffering from osteomyelitis requiring intravenous therapy.

Dendritic cells are early cellular targets of Listeria monocytogenes after intestinal delivery and are involved in bacterial spread in the host.

We studied the sequence of cellular events leading to the dissemination of Listeria monocytogenes from the gut to draining mesenteric lymph nodes (MLNs) by confocal microscopy of immunostained tissue sections from a rat ligated ileal loop system. OX-62-positive cells beneath the epithelial lining of Peyer's patches (PPs) were the first Listeria targets identified after intestinal inoculation. These cells had other features typical of dendritic cells (DCs): they were large, pleiomorphic and major histocompatibility complex class II(hi). Listeria were detected by microscopy in draining MLNs as early as 6 h after inoculation. Some 80-90% of bacteria were located in the deep paracortical regions, and 100% of the bacteria were present in OX-62-positive cells. Most infected cells contained more than five bacteria each, suggesting that they had arrived already loaded with bacteria. At later stages, the bacteria in these areas were mostly present in ED1-positive mononuclear phagocytes. These cells were also infected by an actA mutant defective in cell-to-cell spreading. This suggests that Listeria are transported by DCs from PPs to the deep paracortical regions of draining MLNs and are then transmitted to other cell populations by mechanisms independent of ActA. Another pathway of dissemination to MLNs was identified, probably involving free Listeria and leading to the infection of ED3-positive mononuclear phagocytes in the subcapsular sinus and adjacent paracortical areas. This study provides evidence that DCs are major cellular targets of L. monocytogenes in PPs and that DCs may be involved in the early dissemination of this pathogen. DCs were not sites of active bacterial replication, making these cells ideal vectors of infection.

Blind protected specimen brush and bronchoalveolar lavage in ventilated children.

OBJECTIVE: To determine whether nonbronchoscopic protected specimen brush (PSB) and bronchoalveolar lavage (BAL) are contributive for diagnosing ventilator-associated pneumonia in mechanically ventilated children. DESIGN: Prospective study. SETTING: Fifteen-bed pediatric intensive care unit in a university hospital. PATIENTS: A total of 103 mechanically ventilated children, ranging in age from 7 days to 8.8 yrs, most with a high clinical suspicion for bacterial pneumonia. INTERVENTIONS: All the children underwent nonbronchoscopic PSB and BAL. Nonbronchoscopic PSB was performed with a plugged double-sheathed brush and BAL with a double-lumen plugged catheter. Endotracheal secretions and blood cultures were also collected. Open-lung biopsy was performed for any child who died within 7 days after the inclusion in the study, according to the parental consent. MEASUREMENTS AND MAIN RESULTS: The PSB specimens were submitted for bacteriologic quantitative culture (positive threshold, 10(3) colony-forming units [cfu]/mL). The BAL samples were processed for microscopic quantification of the polymorphonuclear cells containing intracellular bacteria (positive threshold, 1%) and quantitative culture (positive threshold, 10(4) cfu/mL). According to diagnostic categories based on clinical, biological, radiologic, and pathologic criteria, 29 children had bacterial pneumonia and 64 did not Ten children were classified as having an uncertain status. Of the 29 children with bacterial pneumonia, 26 (90%) met one of the following three criteria: a) PSB specimen culture, > or =10(3) cfu/mL; b) intracellular bacteria in cells retrieved by BAL, > or =1%; and c) BAL fluid culture, > or =10(4) cfu/mL. In contrast, 56 (88%) of the 64 patients without pneumonia did not. CONCLUSION: The results of this study indicate the following: a) nonbronchoscopic PSB and BAL were feasible in a large population of mechanically ventilated children; b) nonbronchoscopic techniques were contributive for diagnosing ventilator-associated pneumonia in children; and c) a combined diagnostic approach, using nonbronchoscopic PSB and BAL, was superior to using either test alone.

Diagnosis and follow-up of Whipple's disease by amplification of the 16S rRNA gene of Tropheryma whippelii.

Amplification of the 16S rRNA gene of Tropheryma whippelii was performed in eight patients with Whipple's disease and 34 control patients to confirm a diagnosis of Whipple's disease and to monitor the course of disease. Polymerase chain reaction (PCR) tests were positive before treatment in 13 of 15 tissue samples from Whipple's disease patients (gut 8/8; lymph nodes 2/2; bone marrow 1/2; peripheral blood 2/3), in contrast to none of 54 tissue samples from controls. PCR tests converted to negative within 4-6 months in six of the Whipple's disease patients undergoing therapy. These results show that PCR is a reliable and useful tool for diagnosis of Whipple's disease and for monitoring bacterial elimination during antibiotic therapy.

Outbreak of nosocomial urinary tract infections due to Pseudomonas aeruginosa in a paediatric surgical unit associated with tap-water contamination.

An outbreak of 14 cases of urinary tract infections by Pseudomonas aeruginosa, including six symptomatic infections, occurred from September to November 1994 in a paediatric surgical unit. During the outbreak, urine samples from patients and multiple samples from the environment of patients were tested for the presence of P. aeruginosa. Bacterial isolates were studied by pulsed-field gel electrophoresis. Genotypic analysis showed that most of the isolates from children were different. Multiple P. aeruginosa isolates were also found in the tap water, as the only putative source of contamination. Two of these isolates were identified in two infected patients, indicating possible direct contamination of patients via tap water and this was related to the distal colonization of faucets. Bacteria were eradicated from tap water by replacement of taps. The cluster of cases of P. aeruginosa urinary infection was, therefore, related to multiple contaminations through tap water. These results illustrate an unexpected risk of nosocomial infection and emphasizes the importance of checking tap water to prevent bacterial contamination through handwashing in contaminated water.

Comprehensive study of the intestinal stage of listeriosis in a rat ligated ileal loop system.

The intestinal stage of listeriosis was studied in a rat ligated ileal loop system. Listeria monocytogenes translocated to deep organs with similar efficiencies after inoculation of loops with or without Peyer's patches. Bacterial seeding of deep organs was demonstrated as early as 15 min after inoculation. It was dose dependent and nonspecific, as the delta inlAB, the delta hly, and the delta actA L. monocytogenes mutants and the nonpathogenic species, Listeria innocua, translocated similarly to wild-type L. monocytogenes strains. The levels of uptake of listeriae by Peyer's patches and villous intestine were similar and low, 50 to 250 CFU per cm2 of tissue. No listeria cells crossing the epithelial sheet of Peyer's patches and villous intestine were observed by transmission electron microscopy. The lack of significant interaction of listeriae and the follicle-associated epithelium of Peyer's patches was confirmed by scanning electron microscopy. The follicular tissue of Peyer's patches was a preferential site of Listeria replication. With all doses tested, the rate of bacterial growth was 10 to 20 times higher in Peyer's patches than in villous intestine. At early stages of Peyer's patch infection, listeriae were observed inside mononuclear cells of the dome area. Listeriae then disseminated throughout the follicular tissue except for the germinal center. The virulence determinants hly and, to a lesser extent, actA, but not inlAB, were required for the completion of this process. This study suggests that Peyer's patches are preferential sites for replication rather than for entry of L. monocytogenes, due to the presence of highly permissive mononuclear cells whose nature remains to be defined.

Interaction of Neisseria maningitidis with the components of the blood-brain barrier correlates with an increased expression of PilC.

A fatal untreated case of fulminant meningococcemia was examined to investigate the crossing of the blood-brain barrier (BBB) by Neisseria meningitidis. Microscopic examination showed bacteria in vivo adhering to the endothelium of both the choroid plexus and the meninges. Comparison of the isolates cultivated from the blood and the cerebrospinal fluid (CSF) revealed no antigenic variation of the pilin or the class 5 protein, whereas the expression of the PilC protein was greater in the CSF and the choroid plexus than in the blood. This was due to an increased activity of one of the pilC promotors. This higher expression of PilC correlated in vitro with greater adhesiveness to endothelial cells. A mutation in the single pilC locus of this strain abolished in vitro pilus-mediated adhesion to endothelial cells. These data suggest that PilC plays an important role in the crossing of the BBB, likely through pilus-mediated adhesion.

Type-4 pili and meningococcal adhesiveness.

The ability to interact with non-phagocytic cells is a crucial virulence attribute of the meningococcus. Pili play a major role in this process and are the only means yet discovered by which capsulated bacteria may adhere to cells. Pilus-mediated adhesion is a two-step process which requires (i) the expression of the adhesin PilC1 and (ii) the expression of an appropriate pilin variant. Some pilin variants have the ability to modify the degree of adhesiveness through the formation of bundles of pili which increases bacteria-bacteria interactions.

Emergence of vancomycin resistance in the genus Streptococcus: characterization of a vanB transferable determinant in Streptococcus bovis.

Streptococcus bovis NEM760 was isolated from a stool swab collected on admission from a patient as surveillance for vancomycin-resistant enterococci. Strain NEM760 was identified as S. bovis by conventional biochemical methods and partial sequence analysis of its 16S rRNA. This strain was resistant to a low level of vancomycin (MIC, 64 micrograms/ml) but was susceptible to teicoplanin (MIC, 1 micrograms/ml), and vancomycin induced resistance to both glycopeptides. The presence of a vanB-related gene in NEM760 was demonstrated in a PCR assay which enabled specific amplification of a 635-hp internal segment of vanB. Sequence analysis of the corresponding PCR product revealed that it was highly homologous (96% identity) to the prototype vanB sequence of Enterococcus faecalis V583. The VanB resistance of determinant of S. bovis NEM760 was transferred by conjugation to E. faecalis and Enterococcus faecium at a similar frequency of 2 x 10(-5) per donor. SmaI-digested genomic DNAs of independently obtained transconjugants of E. faecalis and E. faecium were analyzed by pulsed-field gel electrophoresis and Southern hybridization with a vanB DNA probe. The electrophoretic and hybridization patterns obtained with all transconjugants of the same species were indistinguishable and revealed vanB-containing chromosomal insertions of approximately 100 kb. These results suggest that the genes mediating VanB-type resistance in S. bovis NEM760 are part of large transferable genetic elements. The results presented in the report demonstrate for the first time the role of streptococci in the dissemination of vancomycin resistance among gram-positive bacteria.

Nosocomial outbreak of Clostridium difficile diarrhea in a pediatric service.

An outbreak of nosocomial diarrhea that occurred in a pediatric orthopedic service between 1 December 1993 and 15 April 1994 is reported. A total of 37 patients (mean age, 9.6 years; range, 2 months-19.3 years) were involved in the outbreak, including six patients with bacteriologically documented Clostridium difficile infection. A multivariate analysis identified lincomycin treatment for at least three days as the only significant risk factor. Stool samples from four asymptomatic patients were also positive for Clostridium difficile and its cytotoxins. Isolates from all patients belonged to serogroup C, were highly resistant to lincomycin, and exhibited the same restriction pattern by pulsed-field gel electrophoresis. The outbreak ended after treatment with lincomycin was discontinued and hygiene control measures were implemented.

[Pneumococcal meningitis in children: should probabilistic antibiotherapy of infectious meningitis be modified?]. / Méningites à pneumocoque de l'enfant: faut-il modifier l'antibiothérapie probabiliste des méningites communautaires?

BACKGROUND: Since a significant proportion of Streptococcus pneumoniae strains is now resistant to penicillin and sometimes to third-generation cephalosporin, it is necessary to reevaluate the initial therapy of bacterial meningitis proposed before identification of the organism and its susceptibility pattern. POPULATION: From 1 January 1992 to 31 March 1994, nine children with acute S pneumoniae meningitis were treated with ceftriaxone plus aminoglycoside as conventional initial therapy. Eight children were less than 1 year-old (five from 3 to 6 months). Five S pneumoniae strains were penicillin-resistant; four had a ceftriaxone minimal inhibitory concentration (MIC) of 0.047 to 0.094 mg/L and one of 1.5 mg/L. Ceftriaxone was given intravenously at doses of 50 mg/kg twice a day to patients less than 12 months old and 100 mg/kg once a day to patients older than 12 months. Intravenous amikacin (7.5 mg/kg twice daily) or netilmicin (3 mg/kg twice daily) were administered in combination. Dexomethasone was given to all children as adjunctive therapy. Follow-up lumbar puncture was performed after 24 to 36 hours of treatment. RESULTS: For each of the nine patients, cerebrospinal fluid was sterile with normal glucose level. After 2 or 4 days, initial therapy had been modified according to antibiogram and MIC. Monotherapy with ceftriaxone was continued in five children. Rifampicin was associated with initial bitherapy in one case. In two other patients, initial empiric therapy was stopped and changed to chloramphenicol. CONCLUSION: No case of bacteriological failure was noted in our patients but evolution of epidemiology and emergence of decreased penicillin sensibility in S pneumoniae strains (55% in our study) suggests that a third antibiotic (vancocin or rifampicin) should be associated with the standard first-line drug when S pneumoniae is suspected.

Chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile.

A case of chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile is reported. A knee prosthesis was installed in a 16-year-old boy for surgical treatment of an osteosarcoma of the femur. Later, the patient suffered a traumatic closed fracture of his patella, and a sterile fluid was aspirated. One month later, the joint displayed inflammation. Culture of the articular fluid yielded a nontoxigenic Clostridium difficile strain. Despite several attempts using conservative medical treatment with penicillins and ornidazole, Clostridium difficile strains with the same antibiotic susceptibility pattern were repeatedly isolated from the joint over an eight-month period. The foreign material was then ablated, and finally, the patient's leg was amputated one year after Clostridium difficile was first isolated. The possible sources of contamination in our case and other reported cases of extraintestinal infection due to Clostridium difficile are discussed.

[Fetal and neonatal immune thrombocytopenias. Study group "Mother-child immune thrombopenias"]. / Thrombopénies foetales et néonatales immunes. Le groupe d'étude "Thrombopénies immunes mère-enfant".

Neonatal thrombocytopenia has benefited from the advances achieved during the last few years in platelet immunology and foetal therapy. The major risk of the disease is cerebral haemorrhage resulting in death or neurological sequelae. Establishing the aetiological diagnosis of immune thrombocytopenia makes it possible nowadays to apply the appropriate treatment and eventually to take care of future pregnancies. Treatments in utero of foeto-maternal alloimmunization have radically altered the natural course of foetal thrombocytopenia, thereby permitting the management of pregnancies at risk. On the other hand, so far no prenatal treatment has proved to be effective against thrombocytopenia due to maternal autoimmunity.