Rapid diagnosis of Clostridium difficile infection by multiplex real-time PCR

The gold standards for the diagnosis of Clostridium difficile infections (CDIs) are the cytotoxicity assay and the toxigenic culture. However, both methods are time-consuming and the results are not available before 24-48 h. We developed and evaluated a multiplex in-house real-time polymerase chain reaction (PCR) assay for the simultaneous detection of toxigenic strains of C. difficile and the presumptive identification of the epidemic NAP1/027/BI strain from stools. Amplifications were performed using specific primers for tcdB and tcdC on an ABI Prism 7300 (Applied Biosystems). The detection of amplicons was done using TaqMan probes. The analytical sensitivity of the multiplex real-time PCR for detecting tcdB was estimated to 10 CFU/g of stools. This assay was assessed from 881 consecutive unformed stools from patients suspected of having CDI. The gold standard was the toxigenic culture for the diagnosis of CDI and PCR ribotyping for the identification of the NAP1/027/BI strain. The prevalence of positive toxigenic culture was 9.31%. Compared to the toxigenic culture, the sensitivity, specificity, and positive and negative predictive values were 86.59%, 97.43%, 78.02%, and 98.57%, respectively, for the real-time PCR and 70.73%, 100%, 100%, and 97.08%, respectively, for the cytotoxicity assay.

Induction of cementogenesis and periodontal ligament regeneration by recombinant human transforming growth factor-beta3 in Matrigel with rectus abdominis responding cells

BACKGROUND AND OBJECTIVE

In primates and in primates only, the transforming growth factor-b proteins induce endochondral bone formation. Transforming growth factor-b3 also induces periodontal tissue regeneration. Two regenerative treatments using human recombinant transforming growth factor-b3 were examined after implantation in mandibular furcation defects of the nonhuman primate, Papio ursinus.

MATERIAL AND METHODS

Class III furcation defects were surgically created bilaterally in the mandibular first and second molars of two adult Chacma baboons (P. ursinus). Different doses of recombinant transforming growth factor-beta3 reconstituted with Matrigel matrix were implanted in the rectus abdominis muscle to induce heterotopic ossicles for subsequent transplantation to selected furcation defects. Twenty days after heterotopic implantation, periodontal defects were re-exposed, further debrided and implanted with minced fragments of induced heterotopic ossicles. Contralateral class III furcation defects were implanted directly with recombinant transforming growth factor-beta3 in Matrigel matrix with the addition of minced fragments of autogenous rectus abdominis muscle. Treated quadrants were not subjected to oral hygiene procedures so as to study the effect of the direct application of the recombinant morphogen in Matrigel on periodontal healing. Histomorphometric analyses on undecalcified sections cut from specimen blocks harvested on day 60 measured the area of newly formed alveolar bone and the coronal extension of the newly formed cementum along the exposed root surfaces.

RESULTS

Morphometric analyses showed greater alveolar bone regeneration and cementogenesis in furcation defects implanted directly with 75 microg of transforming growth factor-beta3 in Matrigel matrix with the addition of minced muscle tissue.

CONCLUSION

Matrigel matrix is an optimal delivery system for the osteogenic proteins of the transforming growth factor-beta superfamily, including the mammalian transforming growth factor-beta3 isoform. The addition of minced fragments of rectus abdominis muscle provides responding stem cells for further tissue induction and morphogenesis by the transforming growth factor-beta3 protein.

Cementogenesis and the induction of periodontal tissue regeneration by the osteogenic proteins of the transforming growth factor-beta superfamily

The antiquity and severity of periodontal diseases are demonstrated by the hard evidence of alveolar bone loss in gnathic remains of the Pliocene/Pleistocene deposits of the Bloubank Valley at Sterkfontein, Swartkrans and Kromdrai in South Africa. Extant Homo has characterized and cloned a superfamily of proteins which include the bone morphogenetic proteins that regulate tooth morphogenesis at different stages of development as temporally and spatially connected events. The induction of cementogenesis, periodontal ligament and alveolar bone regeneration are regulated by the co-ordinated expression of bone morphogenetic proteins. Naturally derived and recombinant human bone morphogenetic proteins induce periodontal tissue regeneration in mammals. Morphological analyses on undecalcified sections cut at 3-6 mum on a series of mandibular molar Class II and III furcation defects induced in the non-human primate Papio ursinus show the induction of cementogenesis. Sharpey's fibers nucleate as a series of composite collagen bundles within the cementoid matrix in close relation to embedded cementocytes. Osteogenic protein-1 and bone morphogenetic protein-2 possess a structure-activity profile, as shown by the morphology of tissue regeneration, preferentially cementogenic and osteogenic, respectively. In Papio ursinus, transforming growth factor-beta(3) also induces cementogenesis, with Sharpey's fibers inserting into newly formed alveolar bone. Capillary sprouting and invasion determine the sequential insertion and alignment of individual collagenic bundles. The addition of responding stem cells prepared by finely mincing fragments of autogenous rectus abdominis muscle significantly enhances the induction of periodontal tissue regeneration when combined with transforming growth factor-beta(3) implanted in Class II and III furcation defects of Papio ursinus.

Effect of antibiotic therapy on human fecal microbiota and the relation to the development of Clostridium difficile

The gastrointestinal tract is a complex ecosystem. Recent studies have shown that the human fecal microbiota is composed of a consortium of microorganism. It is known that antibiotic treatment alters the microbiota, facilitating the proliferation of opportunists that may occupy ecological niches previously unavailable to them. It is therefore important to characterize resident microbiota to evaluate its latent ability to permit the development of pathogens such as Clostridium difficile. Using samples from 260 subjects enrolled in a previously published clinical study on antibiotic-associated diarrhea, we investigated the possible relationship between the fecal dominant resident microbiota and the subsequent development of C. difficile. We used molecular profiling of bacterial 16S rDNA coupled with partial least square (PLS) regression analysis. Fecal samples were collected on day 0 (D0) before antibiotic treatment and on day 14 (D14) after the beginning of the treatment. Fecal DNA was isolated, and V6-to-V8 regions of the 16S rDNA were amplified by polymerase chain reaction with general primers and analyzed by temporal temperature gradient gel electrophoresis (TTGE). Main bacteria profiles were compared on the basis of similarity (Pearson correlation coefficient). The characteristics of the microbiota were determined using PLS discriminant analysis model. Eighty-seven TTGE profiles on D0 have been analyzed. The banding pattern was complex in all cases. The subsequent onset of C. difficile was not revealed by any clustering of TTGE profiles, but was explained up to 46% by the corresponding PLS model. Furthermore, 6 zones out of the 438 dispatched from the TTGE profiles by the software happened to be specific for the group of patients who acquired C. difficile. The first approach in the molecular phylogenetic analysis showed related sequences to uncultured clones. As for the 87 TTGE profiles on D14, no clustering could be found either, but the subsequent onset of C. difficile was explained up to 74.5% by the corresponding PLS model, thus corroborating the results found on D0. The non exhaustive data of the microbiota we found should be taken as the first step to assess the hypothesis of permissive microbiota. The PLS model was used successfully to predict C. difficile development. We found that important criteria in terms of main bacteria could be markedly considered as predisposing factors for C. difficile development. Yet, the resident microbiota in case of antibiotic-associated diarrhea has still to be analyzed. Furthermore, these findings suggest that strategies reinforcing the ability of the fecal microbiota to resist to modifications would be of clinical relevance.

Emergence of Clostridium difficile toxinotype III, PCR-ribotype 027-associated disease, France, 2006

On 27 March 2006, the Institut de Veille Sanitaire (InVS) was alerted to a cluster of Clostridium difficile associated disease (CDAD) in a healthcare facility in northern France

First cluster of C. difficile toxinotype III, PCR-ribotype 027 associated disease in France: preliminary report

On 27 March 2006, a cluster of cases of Clostridium difficile associated disease (CDAD) in a hospital in northern France (hospital A) was notified to the Institut de Veille Sanitaire

Cathéters à chambre implantable : épidémiologie des complications et étude microbiologique des dispositifs après ablation

Totally implantable venous access ports (TIVAP) are valuable medical devices for long-term intravenous treatment such as parenteral nutrition, cancer chemotherapy or antiviral therapy. Implantation and use of these devices are each associated with infectious or mechanical complications.

AIMS OF THE STUDY

To determine the frequency of complications and to analyze bacterial contamination of different parts of TIVAP (tip, septum, internal lumen of the port).

MATERIAL AND METHODS

Clinical charts of patients, which TIVAP was removed between April 20th to December 31st 2003, were retrospectively reviewed. Infectious complications (local and septicemic) and non-infectious complications (i.e. obstruction, thrombosis, drug extravasation...) were defined using clinical and/or microbiological criteria. Quantitative culture from different parts of the TIVAP was performed.

RESULTS

One hundred and ten patients (age 57 +/- 14-years-old, 94.3% cancers) were included, corresponding to 57,018 catheter-days: 39.1% had one or more non-infectious complications (density incidence: 0.86 for 1000 catheter-days). Among the 49 complications, obstruction, thrombosis, extravasations and malposition accounted for 30.6%, 30.6% 4.1% and 6% of cases. Twenty-one patients (19.1%) had an infectious complication: 11 were local and 14 were systemic (density incidence 0.43 for 1000 catheter-days). Bacteria responsible for TIVAP-associated bacteraemia were coagulase negative staphylococci (N = 2), Staphylococcus aureus susceptible to methicilline (N = 3), micrococci (N = 1), corynebacteria (N = 1) or Gram-negative bacilli (N = 8). Comparison of quantitative culture of the different parts of TIVAP with a threshold at 10(3) CFU/ml showed that culture of tip, septum and port has a sensitivity of 47.6% 57.1% and 61.9 %, respectively and a specificity of 100% 92.1% and 92.1%, respectively for the diagnosis of TIVAP infection.

CONCLUSION

Complications associated to TIVAP are frequent but incidence that we have reported is comparable with previous studies. Analysis of internal lumen of the port is the most sensitive method for the diagnosis of TIVAP-associated infections.

CdeA of Clostridium difficile, a New Multidrug Efflux Transporter of the MATE Family

The cdeA gene, cloned from Clostridium difficile clinical strain 714 under the control of its natural promoter made Escherichia coli and Clostridium perfringens resistant to ethidium bromide and acriflavin but had no effect on the susceptibility of the hosts to the following antibiotics: norfloxacin, ciprofloxacin, gentamicin, erythromycin, tetracyclin, and chloramphenicol. However, it was responsible for fluoroquinolone resistance in E. coli when it was cloned under the control of the Plac promoter. Quantitative reverse transcriptase (RT)-PCR showed that growth of C. difficile clinical strain 253 in the presence of subinhibitory concentrations of ethidium bromide significantly increased the transcription of cdeA, but this was not observed with ciprofloxacin. The deduced protein was homologous to the protein sequences of known efflux pumps from the third cluster (the so-called DinF branch) of the multidrug and toxic compound extrusion (MATE) family. CdeA caused ethidium bromide energy-dependent efflux in whole cells of E. coli. Efflux activity was stimulated by addition of Na+ ions, suggesting that CdeA, like other pumps of the MATE family, is a Na+-coupled efflux pump. CdeA is the first multidrug efflux transporter identified in C. difficile.

A European survey of diagnostic methods and testing protocols for Clostridium difficile

OBJECTIVE

To conduct a survey of the methods used in clinical microbiology laboratories in Europe to diagnose infection with Clostridium difficile.

METHODS

A questionnaire was devised and sent to a co-ordinating member of the Study Group in each of eight European countries. This co-ordinator was in charge of forwarding the questionnaire to hospital laboratories arbitrarily selected. The number of laboratories in each country was determined on the basis of one laboratory for 10,000 beds of hospitalization. This questionnaire covered different aspects pertaining to Clostridium difficile associated to diarrhea (CDAD) diagnosis such as circumstances of request, criteria used for undertaking C. difficile investigations, methods used for the diagnosis, etc.

RESULTS

A total of 212 questionnaires were completed and submitted for analysis: 87.7% of laboratories reported routinely performing C. difficile diagnostic tests. Methods used included toxin detection (93%), culture (55%), and glutamate dehydrogenase (GDH) detection (5.9%). Among the laboratories detecting toxins, different enzyme immunoassays (EIA) and cytotoxicity assays were used in 79% and 17.3% of cases, respectively. Among the different strategies reported, 4.8% were considered suboptimal for the diagnosis of C. difficile infections, but marked discrepancies could be observed between countries. The overall incidence (median) of CDAD was estimated at 1.1 for 1,000 patient admissions.

CONCLUSION

The results of this study suggest marked discrepancies between laboratories and also between countries regarding the criteria by which C. difficile is investigated for, and the methods and the strategies that are used for the diagnosis of C. difficile. These discrepancies could be explained by the lack of clear guidelines for C. difficile diagnosis in each country, and by the importance that physicians attach to C. difficile. Precise guidelines for C. difficile diagnosis would be the first step to make possible accurate comparison of the incidence and the epidemiology of CDAD from one hospital to another or from one country to another.

Antibiotic-associated diarrhoea and Clostridium difficile in the community

BACKGROUND

Clostridium difficile is the main cause of nosocomial infectious diarrhoea and the causative agent of antibiotic-associated colitis. The involvement of C. difficile infection in antibiotic-associated diarrhoea in the community is poorly documented.

METHODS

We studied prospectively 266 adult out-patients in the Paris (France) area who were prescribed a 5-10-day course of antimicrobial chemotherapy. Stools were screened for C. difficile before and 14 days after the start of treatment by standard culture, toxigenic culture and testing for the cytopathic effect of toxin B. Patients were requested to note daily stool frequency and consistency. Diarrhoea was defined as the passage of at least three loose stools per day.

RESULTS

Forty-six (17.5%) of the 262 assessable patients had diarrhoea during the study period. Diarrhoea was mild and self-limited in all patients, and lasted for only 1 day in 65.6% of cases. C. difficile was isolated before and after treatment from one patient, who did not develop diarrhoea. C. difficile was detected only on day 14 in 10 patients (3.8%). The isolate was toxin producing in seven patients. Four of these seven patients had mild self-limited diarrhoea. Toxin-producing C. difficile was isolated significantly more frequently from patients who had diarrhoea than from those who were diarrhoea free (8.7% vs. 1.4%, P = 0.02).

CONCLUSION

The acquisition of toxin-producing C. difficile appears to be frequent during antimicrobial chemotherapy in the community [estimated rate of 2700 (1150-5400) cases per 100 000 exposures to antibiotics]. However, C. difficile is not the main agent of mild antibiotic-associated diarrhoea in out-patients.

[Complications due to peripheral venous catheterization. Prospective study]

OBJECTIVE

Peripheral venous catheter (PVC)-associated complications were prospectively evaluated in a 2 month-study performed in 3 different wards.

METHODS

For each inserted PVC, the following complications were observed daily by an external investigator: tenderness, erythema, swelling or induration, palpable cord and purulence. PVC that were removed were systematically sent to the Microbiology department and analysed according to the semi-quantitative method described by Brun-Buisson et al.

RESULTS

A total of 525 PVC (corresponding to 1,036 catheterisation-days) were included. Main clinical complications were erythema (22.1%), tenderness (21.9%), swelling or induration (20.9%), palpable cord (2.7%) and purulence (0.2%). Phlebitis, defined by 2 or more of the following signs: tenderness, erythema, swelling or induration and palpable cord, was observed in 22%. Catheter colonization (> or = 103 CFU/ml) occurred in 13%. Bacteria isolated from colonized catheters were coagulase-negative staphylococci (88.1%), Staphylococcus aureus (7.1%) and Candida sp. (4.8%). Multivariate risk factor analysis showed that age > or = 55 y. (OR = 3.16, p = 0.003), insertion on articulation site (OR = 2.94, p = 0.01) or in jugular vein (OR = 8.18, p = 0.01) and > 72 hour-catheterisation (OR = 4.74, p = 0.0003) were significantly associated with PVC colonization. Risk factors for phlebitis were skin lesions (OR = 1.88, p < 0.016), active infection unrelated to PVC (OR = 2.8, p = 0.001), "poor quality" peripheral vein (OR = 2.46, p < 0.02) and > 72 hour-catherisation (OR = 2.38, p = 0.009).

CONCLUSION

Complications associated with peripheral venous catheters are frequent but remain benign. They could probably be reduced by a systematic change every 72-96 hours as recommended by different guidelines.

A new crystalline phase of nitric acid dihydrate

The crystal structure of a new high-temperature phase of nitric acid dihydrate, HNO(3).2H(2)O, has been determined at 225 K by single-crystal X-ray diffraction. The H atom of the nitric acid is delocalized to one water molecule, leading to an association of equimolar NO(3)(-) and H(5)O(2)(+) ionic groups. The asymmetric unit contains two molecules of HNO(3).2H(2)O. The two independent molecules are related by a pseudo-twofold c axis, by a translation of 0.54 (approximately (1/2)) along b, with a mean atomic distance difference of 0.3 A, except for one H atom of the water molecules (1.5 A), because of their different orientations in the two molecules. The two independent molecules, linked by strong hydrogen bonds, are arranged in layers. These layers are linked by weaker hydrogen bonds oriented approximately along the c axis. A three-dimensional hydrogen-bond network is observed.

Epidemiology of Clostridium difficile-associated infections

Clostridium difficile is responsible for 15-25% of cases of antibiotic-associated diarrhea (AAD) and for virtually all cases of antibiotic-associated pseudomembranous colitis (PMC). This anaerobic bacterium has been identified as the leading cause of nosocomial infectious diarrhea in adults and can be responsible for large outbreaks. Nosocomial C. difficile infection results in an increased length of stay in hospital ranging from 8 to 21 days. Risk factors for C. difficile-associated diarrhea include antimicrobial therapy, older age (>65 years), antineoplastic chemotherapy and length of hospital stay. Other interventions with high risk associations are enemas, nasogastric tubes, gastrointestinal surgery and antiperistaltic drugs. Prospective studies have shown that nosocomial transmission of C. difficile is frequent but often remains asymptomatic. Patients can be contaminated from environmental surfaces, shared instrumentation, hospital personnel hands and infected roommates. Once an outbreak starts, C. difficile may be spread rapidly throughout the hospital environment where spores may persist for months. Measures that are effective in reducing incidence of C. difficile infections and cross-infection include: (i) an accurate and rapid diagnosis, (ii) appropriate treatment, (iii) implementation of enteric precautions for symptomatic patients, (iv) reinforcement of hand-washing, (v) daily environmental disinfection, and (vi) a restrictive antibiotic policy. C. difficile is a common cause of infectious diarrhea and should be therefore systematically investigated in patients with nosocomial diarrhea.

Periodontal tissue regeneration by combined applications of recombinant human osteogenic protein-1 and bone morphogenetic protein-2. A pilot study in Chacma baboons (Papio ursinus)

Native and recombinant human bone morphogenetic/osteogenic proteins (BMPs/ OPs) singly initiate bone induction in vivo. The finding of synchronous but spatially different BMPs/OPs expression during periodontal tissue morphogenesis suggests novel therapeutic approaches using morphogen combinations based on recapitulation of embryonic development. Twelve furcation defects prepared in the first and second mandibular molars of three adult baboons (Papio ursinus) were used to assess whether qualitative histological aspects of periodontal tissue regeneration could be enhanced and tissue morphogenesis modified by combined or single applications of recombinant hOP-1 and hBMP-2. Doses of BMPs/OPs were 100 microg of each protein per 1 g of insoluble collagenous bone matrix as carrier. Approximately 200 mg of carrier matrix was used per furcation defect. Undecalcified sections cut for histological analysis 60 d after healing of hOP-1-treated specimens showed substantial cementogenesis with scattered remnants of the collagenous carrier. hBMP-2 applied alone induced greater amounts of mineralized bone and osteoid when compared to hOP-1 alone or to combined morphogen applications. Combined applications of hOP-1 and hBMP-2 did not enhance alveolar bone regeneration or new attachment formation over and above the single applications of the morphogens. The results of this study, which is the first to attempt to address the structure-activity relationship amongst BMP/OP family members, indicate that tissue morphogenesis induced by hOP-1 and hBMP-2 is qualitatively different when the morphogens are applied singly, with hOP-1 inducing substantial cementogenesis. hBMP-2 treated defects, on the other hand, showed limited cementum formation but a temporal enhancement of alveolar bone regeneration and remodelling. The demonstration of therapeutic mosaicism in periodontal regeneration will require extensive testing of ratios and doses of recombinant morphogen combinations for optimal tissue engineering in clinical contexts.

Pseudo-outbreak of Mycobacterium gordonae associated with water from refrigerated fountains

Between March 1997 and December 1997, acid-fast bacilli (AFB) were detected on sputum and/or gastric aspirates smears from five patients hospitalized in the chest medicine department. These specimens grew M. gordonae. Based on AFB-positive smear and clinical presentation, four out of five patients received antituberculous treatment until species identification was known. Epidemiological investigation revealed a heavy contamination of water collected from refrigerated fountains located on the same floor as the patient cases. Strains isolated from four patients and the refrigerated fountain exhibited the same pulsed gel electrophoresis pattern (using DraI and XbaI enzymes) suggesting that positive smears were related to drinking water from the refrigerated fountain. This cluster of pseudo-infections underlines the necessity for a proper maintenance of water supply equipment in order to avoid inappropriate decisions deleterious for patients.

Antitumour activity of heparin on metastatic colon cancer

We present the case history of a 47-year-old patient with metastatic colon cancer, whose anticoagulant treatment led to a prolonged disease-free survival.

Tamoxifen adjuvant treatment duration in early breast cancer: initial results of a randomized study comparing short-term treatment with long-term treatment. Fédération Nationale des Centres de Lutte Contre le Cancer Breast Group

PURPOSE

In 1986, The Fédération Nationale desCentres de Lutte Contre le Cancer Breast Group initiated a multicenter randomized trial to assess the usefulness of long-term adjuvant tamoxifen treatment. Short-term adjuvant tamoxifen treatment was to be compared with life long adjuvant tamoxifen treatment.

PATIENTS AND METHODS

Patients who were disease-free after 2 to 3 years of adjuvant tamoxifen treatment were eligible for the trial. From September 1986 to May 1995, 3,793 patients were randomized from France, Belgium, and Argentina. A total of 1,882 patients stopped tamoxifen (short-term group), and 1,911 patients were to continue tamoxifen for life (long-term group) at the same dose as previously prescribed. The protocol was modified in February 1997, limiting tamoxifen treatment to 10 years after randomization, thus giving a comparison between a 2- to 3-year treatment and a 12- to 13-year treatment. To date, the median duration of tamoxifen treatment is 30 months in the short-term group, and 70 months in the long-term group.

RESULTS

Overall, longer tamoxifen treatment induced a 23% reduction in relapse rates, leading to a 7-year disease-free survival rate of 78%, compared with 72% in the shorter-treatment group. In contrast, overall survival did not differ between the two groups, with a 79% overall survival rate in both groups. This improvement in disease-free survival could be observed in node-positive patients (P: =.001); however, it was not found in node-negative patients. Prolonged tamoxifen treatment corresponded to a significant increase in disease-free survival in estrogen receptor-positive patients (P: =.03) as well as in estrogen receptor-negative patients (P: =.05). Furthermore, longer treatment reduced contralateral breast cancers and did not increase the number of endometrial cancers.

CONCLUSION

Although no survival advantage was noted, patients did benefit from longer tamoxifen treatment over 3 years and had significantly better disease-free survival compared with patients who stopped hormonal treatment. Long-term follow-up is needed to assess these results. Most patients in the long-term group are still receiving treatment. Comparison of results as time passes will enable conclusions to be made on the value of long-term treatment over 5 years compared with 2 to 3 years.

[Role of the microbiology laboratory in the diagnosis of nosocomial diarrhea]

Diarrhea that occurs in hospitalized patients is frequent and may be due to infectious or noninfectious causes. In adults with nosocomial diarrhea, the most commonly detected agent is Clostridium difficile; in children, rotaviruses are predominant. Various studies have shown that bacterial enteric pathogens (e.g. Salmonella spp., Shigella spp., Campylobacter spp...) or parasites are common causes of community-acquired diarrhea but rarely cause nosocomial enteritis. Stool cultures for these pathogens and ova and parasite examination should not be performed in patients hospitalized for more than three days unless there are plausible clinical or epidemiological reasons to do so. In contrast, C. difficile toxins assay (and rotavirus screening in children) should be primarily requested. The detection of C. difficile toxin B by stool cytotoxicity assay remains the 'gold standard'. Identification of toxin A (or A + B) can also be performed by immuno-enzymatic (ELISA) tests: results may be obtained in three hours. Electronic microscopy is the standard method for rotavirus diagnosis but tests using latex agglutination or immuno-enzymatic assay are now available. Various typing methods have been developed and may be routinely used in epidemiological investigations.

[Epidemiology, risk factors and prevention of Clostridium difficile nosocomial infections]

Clostridium difficile is responsible for 10-25% of cases of antibiotic-associated diarrhea (AAD) and for virtually all cases of antibiotic-associated pseudo-membranous colitis (PMC). This anaerobic spore-forming bacterium has been identified as the leading cause of nosocomial infectious diarrhea in adults. Pathogenesis relies on a disruption of the normal bacterial flora of the colon, a colonization by C. difficile and the release of toxins A and B that cause mucosal damage and inflammation. Incidence of C. difficile intestinal disorders usually varies from one to 40 per thousand patient admissions. Risk factors for C. difficile-associated diarrhea include antimicrobial therapy, older age (> 65 years), antineoplastic chemotherapy, and length of hospital stay. Nosocomial transmission of C. difficile via oro-fecal route occurs in 3-30% of total patient admissions but it remains asymptomatic in more than 66% of cases. Persistent environmental contamination and carrying of the organism on the hands of hospital staff are common. Measures that are effective in reducing cross-infection consist of an accurate and rapid diagnosis, an appropriate treatment, an implementation of enteric precautions for symptomatic patients, a reinforcement of hand-washing and a daily environmental disinfection. C. difficile is a common cause of infectious diarrhea and should be therefore systematically investigated in patients with nosocomial diarrhea.

Comparison of PCR-ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis for typing Clostridium difficile

Clostridium difficile is now recognized as the major agent responsible for nosocomial diarrhea in adults. Among the genotyping methods available, arbitrarily primed PCR (AP-PCR), PCR-ribotyping, and pulsed-field gel electrophoresis (PFGE) have been widely used for investigating outbreaks of C. difficile infections. However, the comparative typing ability, reproducibility, discriminatory power, and efficiency of these methods have not been fully investigated. We compared the results of three methods-AP-PCR with three different primers (AP3, AP4, and AP5), PCR-ribotyping, and PFGE (with SmaI endonuclease)-to differentiate 99 strains of C. difficile that had been previously serogrouped. Typing abilities were 100% for PCR-ribotyping and AP-PCR with AP3 and 90% for PFGE, due to early DNA degradation in strains from serogroup G. Reproducibilities were 100% for PCR-ribotyping and PFGE but only 88% for AP-PCR with AP3, 67% for AP-PCR with AP4, and 33% for AP-PCR with AP5. Discriminatory power for unrelated strains was >0.95 for all the methods but was lower for PCR-ribotyping among serogroups D and C. PCR-based methods were easier and quicker to perform, but their fingerprints were more difficult to interpret than those of PFGE. We conclude that PCR-ribotyping offers the best combination of advantages as an initial typing tool for C. difficile.

Usefulness of simultaneous detection of toxin A and glutamate dehydrogenase for the diagnosis of Clostridium difficile-associated diseases

The aim of this study was to evaluate an immunoassay (Triage; Biosite Diagnostics, BMD, France) for detecting both a specific antigen of Clostridium difficile (glutamate dehydrogenase [GDH]) and toxin A. Evaluation of the test was carried out in 304 fecal samples from patients suspected of having Clostridium difficile-associated diseases. The results with GDH and toxin A were compared with those of a culture and cytotoxicity assay (toxin B). The prevalence rates for toxin B-positive and culture-positive fecal samples were 11.2% and 25%, respectively. The sensitivity of the Triage immunoassay was 90.8% for GDH and 79.4% for toxin A. A negative result with both toxin A and GDH was very reliably able to eliminate a diagnosis of Clostridium difficile-associated disease (negative predictive value 99.6%). Triage is a very rapid (20 min) and easy-to-perform test. It could be useful for diagnostic purposes and also for detecting nontoxigenic strains in epidemiogical studies.

Epidemiology of recurrences or reinfections of Clostridium difficile-associated diarrhea

Approximately 15 to 35% of patients with a first episode of Clostridium difficile-associated diarrhea relapse within 2 months. Between 1994 and 1997, strains from 93 hospitalized patients with C. difficile recurrences were fingerprinted by using both serotyping and PCR-ribotyping. The results showed that 48.4% of clinical recurrences were, in fact, reinfections with a different strain of C. difficile. Rates of clinical recurrences could therefore be reduced by implementing strict isolation precautions.

Epidemiology of recurrences or reinfections of Clostridium difficile-associated diarrhea

Approximately 15 to 35% of patients with a first episode of Clostridium difficile-associated diarrhea relapse within 2 months. Between 1994 and 1997, strains from 93 hospitalized patients with C. difficile recurrences were fingerprinted by using both serotyping and PCR-ribotyping. The results showed that 48.4% of clinical recurrences were, in fact, reinfections with a different strain of C. difficile. Rates of clinical recurrences could therefore be reduced by implementing strict isolation precautions.

Antimicrobial susceptibilities and serogroups of clinical strains of Clostridium difficile isolated in France in 1991 and 1997

Glycopeptides (vancomycin and teicoplanin) and metronidazole are the drugs of choice for the treatment of Clostridium difficile infections, but trends in susceptibility patterns have not been assessed in the past few years. The objective was to study the MICs of glycopeptides and metronidazole for unrelated C. difficile strains isolated in 1991 (n = 100) and in 1997 (n = 98) by the agar macrodilution, the E-test, and the disk diffusion methods. Strain susceptibilities to erythromycin, clindamycin, tetracycline, rifampin, and chloramphenicol were also determined by the ATB ANA gallery (bioMérieux, La Balme-les-Grottes, France). The MICs at which 50% of isolates are inhibited (MIC(50)s) and MIC(90)s of glycopeptides and metronidazole remained stable between 1991 and 1997. All the strains were inhibited by concentrations that did not exceed 2 microgram/ml for vancomycin and 1 microg/ml for teicoplanin. Comparison of MICs determined by the agar dilution method recommended by the National Committee for Clinical Laboratory Standards and the E test showed correlations (+/-2 dilutions) of 86. 6, 95.9, and 99% for metronidazole, vancomycin, and teicoplanin, respectively. The E test always underestimated the MICs. Strains with decreased susceptibility to metronidazole (MICs, >/=8 microgram/ml) were isolated from six patients (n = 4 in 1991 and n = 2 in 1997). These strains were also detected by the disk diffusion method (zone inhibition diameter, </=21 mm); they belonged to nontoxigenic serogroup D (n = 5) and toxigenic serogroup H (n = 1). Decreased susceptibility to erythromycin (MICs, >/=1 microgram/ml), clindamycin (MICs, >/=2 microgram/ml), tetracycline (MICs, >/=8 microgram/ml), rifampin (MICs, >/=4 microgram/ml), and chloramphenicol (MICs, >/=16 microgram/ml) was observed in 64.2, 80.3, 23.7, 22.7, and 14.6% of strains, respectively. Strains isolated in 1997 were more susceptible than those isolated in 1991, and this trend was correlated to a major change in serogroup distribution. Periodic studies are needed in order to detect changes in serogroups and the emergence of strains with decreased susceptibility to therapeutic drugs.

A supernumerary tooth in a 1.7 million-year-old Australopithecus robustus from Swartkrans, South Africa

The maxillary dental arch of a partial cranium of an adult specimen of Australopithecus robustus shows the presence of a supernumerary tooth between the right first and second incisors. The fossil specimen, SK 83, is from Swartkrans Member 1 sediments, considered, on the basis of associated fauna, to be approximately 1.7 million yr old. The specimen was analyzed macroscopically, stereomacroscopically and by X-ray computed tomography. The anatomic position and the morphology of the tooth are consistent with a diagnosis of supernumerary lateral incisor rather than a mesiodens or a retained deciduous tooth. This is the first description of a supernumerary tooth found in Plio-Pleistocene hominid fossils from South African cave deposits.

Detection of hepatitis C virus RNA (HCV RNA) in amniotic fluid: a prospective study

BACKGROUND/AIMS

Mother-to-infant transmission of hepatitis C virus (HCV) has been reported, but the transmission route is unknown. The aim of our study was to detect HCV RNA in amniotic fluid of pregnant women seropositive for HCV.

METHODS

Twenty-two HCV seropositive women were included in the study (median age: 39 years). An amniocentesis was performed in all patients during the 4th month of pregnancy. Sixteen women also tested positive for HCV RNA in serum. The range of HCV RNA titers was 0.3 to 15.1x10(6) Eq/ml (Quantiplex HCV RNA 2.0 Assay, Chiron Diagnostics). Of these 16 viremic patients, four had an anterior placenta, ten had a posterior placenta and the position of the placenta was not determined in two cases. PCR (Amplicor HCV, Roche Diagnostics) was used to detect HCV RNA in the amniotic fluid. We also studied 11 HCV seronegative women as a control group.

RESULTS

In the viremic group (n = 16), HCV RNA was detected once in amniotic fluid. The positive specimen was collected from a patient with an HCV RNA serum value equal to 1.1x10(6) Eq/ml. The placenta was in an anterior position. A PCR inhibitor was detected in one case. No HCV RNA was detected in the amniotic fluid of six seropositive non-viremic patients, nor in the control group. Serum HCV RNA was negative in the ten children tested. The woman whose amniotic fluid contained HCV RNA was the mother of one of them.

CONCLUSIONS

HCV RNA detection in amniotic fluid is rarely positive. The anterior position of the placenta in the only positive detection cannot rule out contamination of the amniotic fluid during the transplacental amniocentesis.

Comparative value of colonic biopsy and intraluminal fluid culture for diagnosis of bacterial acute colitis in immunocompetent patients. Infectious Colitis Study Group

We compared the yield of intraluminal fluid culture to that of biopsy specimens obtained during colonoscopy for the diagnosis of bacterial colitis in 93 immunocompetent patients with a recent episode of diarrhea and macroscopic lesions of colitis. Stool culture findings were also available for 68 patients. At least one bacterial pathogen was isolated from the biopsy specimen, intraluminal fluid, or stool from 48 patients (51.6%). Salmonella species, Clostridium difficile, Klebsiella oxytoca, Shigella species, and Campylobacter species were recovered from 16 (17.2%), 15 (16.1%), 8 (8.6%), 7 (7.5%), and 4 (4.3%) of the patients, respectively. One Shigella species and one K. oxytoca strain were isolated from biopsy specimens but not from intraluminal fluid, and intraluminal fluid was the only positive specimen in 12 cases (yielding 1 Salmonella species, 2 Shigella species, 2 K. oxytoca, and 7 C. difficile isolates). In nine cases out of 10, toxin B was detected only in intraluminal fluid. A correlation of 91.2% was observed between stool and intraluminal fluid cultures for Salmonella, Shigella, and Campylobacter species isolations. Culture of biopsy specimens adds little to the diagnosis of infectious colitis, and stools and intraluminal fluids appear to have comparable value.

Development of a new PCR-ribotyping method for Clostridium difficile based on ribosomal RNA gene sequencing

PCR-ribotying, a typing method based on polymorphism in the 16S-23S intergenic spacer region, has been recently used to investigate outbreaks due to Clostridium difficile. However, this method generates bands of high and close molecular masses which are difficult to separate on agarose gel electrophoresis. To improve reading of banding patterns of PCR-ribotyping applied to C. difficile, a partial sequencing of the rRNA genes (16S and 23S) and intergenic spacer region has been performed, then a new set of primers located closer to the intergenic spacer region has been defined. The new PCR gave reproducible patterns of bands easy to separate on agarose gel electrophoresis. Each of the 10 serogroups and 11 subgroups of serogroup A produced a different pattern. This typing method has evidenced major qualities such as easiness, rapidity and reproducibility. However, its discriminatory power has to be evaluated to validate its importance as a typing tool for C. difficile.

Pseudomonas aeruginosa infection in human immunodeficiency virus infected patients

OBJECTIVES

(1) To determine the incidence and outcome of Pseudomonas aeruginosa infection in HIV-infected patients. (2) To study the antimicrobial susceptibility of P. aeruginosa isolates in this particular population. (3) To identify risk factors for these infections.

PATIENTS AND METHODS

A retrospective case-control study performed in a 28-bed infectious-diseases unit in a 940-bed university hospital. All cases were defined as HIV-infected patients with severe infections due to P. aeruginosa, including bacteremia, lower or upper respiratory tract infections, infections related to a central venous catheter, and cutaneous/muscular infection. Each case was matched with an HIV-seropositive control not infected by P. aeruginosa and hospitalized on the same dates as the cases.

RESULTS

One thousand and thirty-five HIV-infected patients were hospitalized during the study period. A first severe P. aeruginosa infection was documented in 41 patients, giving an overall annual incidence note of 2.51 episodes per 100 admissions. Forty of the 41 case notes were available for analysis. They consisted of 17 cases of bacteraemia, four upper respiratory tract infections, 10 lower respiratory tract infections, three catheter-related infections, and six cutaneous/muscular infections. Of these 40 cases, 60% were nosocomial and the remainder were community-acquired. The overall mortality rate was 22% (47% in bacteraemic forms). Twenty five percent of patients relapsed after an average of 37 days. The case-control comparison showed that AIDS was more frequent among the cases (92% vs. 74%, P = 0.04), who also had a lower PN count (P = 0.005), and a lower CD4 cell count (15.7 +/- 18.8/mm3 vs. 118 +/- 211/mm3; P = 0.0007). The number of days spent in hospital in the previous 3 months (29.3 +/- 20.7 vs. 19.7 +/- 14, P = 0.04) was significantly higher among the cases. In a multivariate analysis, examining treatments received in the previous month, only co-trimoxazole [OR = 5.5 (1.1-26.9)], penicillins [OR = 5.2 (1.1-25.3)], steroids [OR = 5.5, (1.2-25.5)] and a CD4 cell count below 50/mm3 [OR = 13.2 (1.4-129.4)] were identified as risk factors.

CONCLUSION

P. aeruginosa infection is a not frequent bacterial disease in highly immunodeficient HIV-infected patients. It is frequently fatal and must be borne in mind in the advanced stages of HIV disease, especially when patients have received co-trimoxazole (trianthoprim-sulphamethoxazole), penicillins or steroids.

Carriage of GB virus C/hepatitis G virus RNA is associated with a slower immunologic, virologic, and clinical progression of human immunodeficiency virus disease in coinfected persons

The prevalence of GB virus C (GBV-C) infection is high in human immunodeficiency virus (HIV)-infected persons. However, the long-term consequences of coinfection are unknown. HIV-positive persons with a well-defined duration of infection were screened on the basis of their GBV-C/hepatitis G virus (HGV) RNA status and studied. GBV-C/HGV viremia was observed in 23, who carried the virus over a mean of 7.7 years. All parameters (survival, CDC stage B/C, HIV RNA load, CD4 T cell count) showed significant differences in terms of the cumulative progression rate between persons positive and negative for GBV-C/HGV RNA. When GBV-C/HGV RNA-positive and -unexposed subjects were matched by age, sex, baseline HIV RNA load, and baseline CD4 T cell count, HIV disease progression appeared worse in GBV-C/HGV RNA-negative subjects. The carriage of GBV-C/HGV RNA is associated with a slower progression of HIV disease in coinfected persons.

Clostridium difficile-associated diarrhea in HIV-infected patients: epidemiology and risk factors

A retrospective analysis of all the cases of Clostridium difficile-associated diarrhea (CDAD) in hospitalized patients infected with HIV was performed over a 52-month period to assess the incidence, epidemiology, and risk factors of CDAD. A case of CDAD was defined as a patient with diarrhea and a positive stool cytotoxin B assay. Sixty-seven cases of CDAD were recorded in HIV-infected patients between January 1991 and April 1995. The annual incidence of CDAD ranged from 1.7 to 6.4 per 100 HIV-infected patients discharged from hospital. The 67 CDAD cases included 48 (72%) first episodes and 19 (28%) relapses. Serogroup C accounted for 69% of strains from initial episodes of CDAD. To identify risk factors for CDAD, 34 HIV-infected patients with a first episode were compared with 66 HIV-infected controls matched for the length of hospital stay. Three independent factors remained significantly associated with CDAD among HIV-infected patients: CD4+ cell counts <50/mm3 (OR = 5.2; 95% CI = 1.4-19.3; p = 0.01), clindamycin use (OR = 5.0; 95% CI = 1.3-18.3; p = 0.02) and penicillin use (OR = 4.6; 95% CI = 1.1-18.8; p = 0.03). C. difficile is a common enteric pathogen responsible for nosocomial diarrhea in HIV-infected patients. Clinicians should keep this pathogen in mind when searching for the cause of diarrhea in these patients, especially those who are severely immunocompromised or have received clindamycin or penicillin.

Risk factors for cirrhosis in patients with chronic hepatitis C virus infection: results of a case-control study

The role of the viral genotype, especially genotype 1b, in the severity of liver injury induced by chronic hepatitis C virus (HCV) infection is unclear, probably because of confounding factors such as the date and mode of contamination. Host genetic or environmental factors such as heterozygous MZ alpha1-antitrypsin deficiency or alcoholism, could also be potential risk factors for the development of cirrhosis. The aim of this study was to compare the prevalence of genotypes, alpha1-antitrypsin phenotype, past hepatitis B virus infection, and alcohol consumption in cirrhotic and noncirrhotic patients with chronic hepatitis C. We conducted a case-control study comparing 84 consecutive cirrhotic patients with chronic hepatitis C (cases) with 84 noncirrhotic patients with chronic hepatitis C (controls) selected from a cohort of 464 patients hospitalized during the same period. Controls were paired with cases according to age, sex, risk factors, and date of infection. HCV genotypes were determined using the InnoLiPA technique (Innogenetics, Zwijnaarde, Belgium) and classified according to the method of Simmonds. Patients were divided in three groups according to alcohol consumption: <30 g/d (light), 30 to 80 g/d (moderate), and >80 g/d (heavy). Cirrhotic and noncirrhotic patients were not significantly different in terms of genotype distribution (1a/1b/2a/3a/others/undetermined: 10/48/7/17/0/2 versus 11/43/10/10/5/5), alpha1-antitrypsin phenotype distribution (MM/MS/MZ: 84%/14%/2% vs. 87%/11%/2%, respectively), and prevalence of antibody to hepatitis B core antigen positivity (29% vs. 23%). Alcohol consumption was significantly different between cases and controls (L/M/H: 58%/27%/16% vs. 76%/15%/9%, respectively; P < .05). Two conclusions regarding patients with chronic hepatitis C virus infection can be drawn from this study: 1) viral genotype, especially 1b, past hepatitis B virus infection, and heterozygous MZ alpha1-antitrypsin deficiency are not risk factors for cirrhosis; and 2) alcohol consumption, even moderate, is a risk factor for cirrhosis.

Even individuals considered as long-term nonprogressors show biological signs of progression after 10 years of human immunodeficiency virus infection

Despite a decade of human immunodeficiency virus (HIV) seropositivity, a few individuals termed as long-term nonprogressors (LTNPs) maintain a stable CD4+ T-cell count for a period of time. The aim of this study was to establish, through the sequential determination of all known predictors of HIV disease, the proportion of such patients having stringent criteria of true long-term nonprogression. Among 249 individuals who were HIV-infected and prospectively followed up over a 10-year period (1985 to 1995), 12 having a CD4+ T-cell count greater than 500/microL (LTNP I group) and 9 having a CD4+ T-cell count less than 500 but stable over time (LTNP II group) after at least 10 years of infection without intervention of antiviral therapy, were studied over the entire follow-up period. The plasma HIV RNA copy number and the serum concentrations of p24 antigen, each anti-HIV antibody, neopterin, beta-2-microglobulin, Immunoglobulin (Ig) G and IgA were determined every 18 months over the study period. Cellular and plasma viremias were cross-sectionaly assayed in all 21 patients. Only two patients had strictly no marker of progression over the follow-up period. They were the only ones who had, over the 10-year period, a viral copy number too low to be detected. The other patients had a viral copy number higher than 400/mL at at least one visit and increasing over the follow-up period, and they evidenced one or more markers of virological or immunological deterioration. Cellular viremia was positive in all patients but two, while plasma viremia was negative in all but one. The population of individuals termed as LTNPs is not virologically and immunologically homogeneous. The majority present biological signs of HIV disease progression. A new pattern of true LTNP can be drawn through stringent criteria based on the whole known predictors. This pattern appears to be rare in HIV-positive population.

[Prospective study of pathogenic agents isolated from feces of patients with HIV infections]

OBJECTIVE

Determine the frequency of enteropathogenic agents isolated in diarrheic feces of patients with HIV infection and to compare findings with a control group (HIV + without diarrhea) in order to identify risk factors.

PATIENTS AND METHODS

All HIV seropositive inpatients and outpatients seropositive for HIV, with or without diarrhea, seen between 1 November 1994 and 30 April 1995 were included. Samples of feces were obtained for culture, virology examination, parasite examination and search for Clostridium difficile. The same samples were obtained in case of diarrhea during the course of hospitalization.

RESULTS

There were 113 samples. Analyses demonstrated a pathogenic agent in 73.6% of the samples in patients with diarrhea and in 31.6% of those without diarrhea. Clostridium difficile and parasites were the most frequently identified agents. An infectious agent was identified in one-fourth of the patients without clinical signs of diarrhea, and in one-fourth of those with diarrhea no pathogen could be demonstrated. No factor of risk for finding a particular microorganism in feces of patients with diarrhea could be identified.

DISCUSSION

The exact pathogenic roles of Pseudomonas aeuriginosa, yeast, and adenovirus remain to be determined. It is hypothesized that the HIV has a direct effect on the host digestive tract.

Killing kinetics of RP 59500 and pristinamycin against penicillin-resistant pneumococci

The killing kinetics of two streptogramins, RP 59500 and pristinamycin against seventeen isolates of penicillin-susceptible and resistant pneumococci were studied. The antibiotics were tested at 1x, 2x and 4x the MIC for each individual isolate. The results showed a very good and rapid bactericidal activity within 1 hour for concentrations equal or greater to the MIC. These antibiotics are very promising agents for the treatment of infections due to multiresistant pneumococci.

Full or partial seroreversion in patients infected by hepatitis C virus

Cases of partial seroreversion have been reported in hemodialyzed or immunodepressed patients, but spontaneous clearance of viremia associated with a disappearance of specific antibodies or clearance while receiving therapy has not been precisely documented in immunocompetent hepatitis C virus (HCV)-infected persons. A longitudinal study of markers of HCV infection in a cohort of 178 multitransfused patients followed over an 8-year period was done to establish well-documented cases of partial or full seroreversion. Thirty (16.8%) of 178 patients were HCV-infected; among them, 5 had partial or full seroreversion. Seroreversion to an anti-HCV-negative state is characterized by a quantitative decrease in antibody. A seroreversion may be observed in three circumstances: spontaneously, induced by therapy, and in conjunction with human immunodeficiency virus infection. Long-term follow-up of seroreverters will establish whether they have definitively eradicated HCV from their systems.

Killing kinetics of meropenem against penicillin-resistant pneumococci

The killing kinetics of meropenem against sixteen clinical isolates of pneumococci (12 penicillin-resistant, three penicillin-intermediate and one penicillin-sensitive) were studied. Meropenem was tested at 1x, 2x and 4x the MIC for each individual isolate. The results showed a good bactericidal activity with rapid killing of pneumococci (killing > 3 log10 cfu/mL was obtained for nine strains). This strategy needs clinical assessment and might prove to be a suitable alternative to penicillin and cephalosporins for the treatment of mixed infections involving multiresistant pneumococci.

Monitoring of cytomegalovirus infection and disease in bone marrow recipients by reverse transcription-PCR and comparison with PCR and blood and urine cultures

Preemptive therapy is a promising strategy for the prevention of serious cytomegalovirus (CMV) disease after bone marrow (BM) transplantation but requires relevant diagnostic tests. We compared the clinical value of a reverse transcription (RT)-PCR method, which detected a late viral mRNA in peripheral blood leukocytes (PBL), with a PCR method that detected the viral DNA in PBL and with viral culture from leukocytes and urine for the diagnosis of symptomatic CMV infection after BM transplantation. Forty-five consecutive BM recipients were prospectively tested at weekly intervals by the four methods. CMV infection, demonstrated either by the culture of CMV or by repeated detection of viral DNA, was observed in 28 patients, but only 14 developed CMV-related clinical symptoms. The clinical sensitivity and specificity of each technique for detection of symptomatic infection were, respectively, 36 and 74% for urine culture, 43 and 84% for leukocyte culture, 100 and 65% for PCR, and 71 and 94% for RT-PCR. Although PCR detection of DNA in PBL was the earliest and most sensitive technique for the diagnosis of CMV infection, RT-PCR was more predictive of the onset of CMV-related clinical symptoms. These data suggest that both molecular methods should be used for identifying BM recipients at highest risk of CMV disease.

Direct infection of CD34+ progenitor cells by human cytomegalovirus: evidence for inhibition of hematopoiesis and viral replication

We successfully infected fluorescence-activated cell-sorted CD34+ cells from normal cord blood by the human cytomegalovirus (HCMV) laboratory strain Towne. An inhibitory effect of HCMV on clonogenic myeloid progenitors was observed in primary methylcellulose cultures. After an initial 7-day liquid culture of CD34(+)-infected cells, this inhibition was further amplified in secondary methylcellulose cultures, then involving both the myeloid and erythroid lineages. Under these conditions, viral DNA was detected both in erythroid and myeloid colonies using the polymerase chain reaction (PCR), but reverse transcription PCR (RT-PCR) failed to detect viral RNA. In contrast, when CD34(+)-infected cells were maintained in liquid suspension, both immediate, early, and late transcripts were detected as soon as day 3. In addition, viral production was demonstrated in the culture supernatants, thus confirming that a complete viral cycle occurred under liquid conditions. Furthermore, by resorting cells into CD34+ and CD34- fractions, we showed by RT-PCR that viral replication took place in cells still expressing CD34 antigen, whereas no RNA was found in more differentiated cells that had subsequently lost their CD34 antigen. These findings suggest that HCMV replication can occur at the early steps of progenitor differentiation and may be involved in the viral-induced myelosuppression.

Quantitation of passively acquired human immunodeficiency virus (HIV) antibodies in AIDS patients transfused with a plasma that is rich in HIV antibodies

BACKGROUND

Passive immunotherapy in human immunodeficiency virus (HIV) infection is based on transfusions of plasma that is rich in HIV antibodies.

STUDY DESIGN AND METHODS

To verify whether the clearance of transfused antibodies will maintain an elevated titer of specific antibodies between biweekly transfusions of plasma, the titers of anti-HIV-1 in plasma and in transfusion recipients were measured. Samples from 12 recipients were analyzed by automated scanning of Western blot, before transfusion and at Days 2, 7, and 14 after transfusion.

RESULTS

The p24 antibody became detectable or higher than the baseline after transfusion and remained detectable until the second transfusion. Anti-p24 titers were variable and dependent on the antibody titer of the transfused plasma and the baseline p24 antigen titer.

CONCLUSION

Biweekly transfusion of plasma with a high anti-HIV titer maintains a high anti-p24 titer between transfusions in AIDS patients treated with passive immunotherapy.

Prevalence and pathogenicity of Clostridium difficile in hospitalized patients. A French multicenter study

BACKGROUND

Although Clostridium difficile is the main agent responsible for nosocomial diarrhea in adults, its prevalence in stool cultures sent to hospital microbiology laboratories is not clearly established.

OBJECTIVES

To determine the prevalence of C difficile in inpatient stools sent to hospital microbiology laboratories and to assess the relationship between serotypes and toxigenicity of the strains isolated and the clinical data.

METHODS

From January 18, 1993, to July 31, 1993, the presence of C difficile was systematically investigated in a case-control study on 3921 stool samples sent for stool culture to 11 French hospital microbiology laboratories. The prevalence of C difficile in this population (cases) was compared with that of a group of 229 random hospital controls matched for age, department, and length of stay (controls). Stool culture from controls was requested by the laboratory although not prescribed by the clinical staff. Serotype and toxigenesis of the strains isolated were compared.

RESULTS

The overall prevalence of C difficile in the cases was twice the prevalence in the controls (9.7% vs 4.8%; P < .001) and was approximately 4 times as high in diarrheal stools (ie, soft or liquid) as in normally formed stools from controls (11.5% vs 3.3%; P < .001). The strains isolated from diarrheal stools were more frequently toxigenic than those isolated from normally formed stools. Serogroup D was never toxigenic, and its proportion was statistically greater in the controls than in the cases (45% vs 18%; chi 2 = 5.2; P < .05). Conversely, serogroup C was isolated only from the cases. Clostridium difficile was mainly found in older patients ( > 65 years), suffering from a severe disabling disease, who had been treated with antibiotics and hospitalized for more than 1 week in long-stay wards or in intensive care.

CONCLUSIONS

This multicenter period prevalence study clearly supports the hypothesis of a common role of C difficile in infectious diarrhea in hospitalized patients. Disease associated with C difficile should therefore be systematically evaluated in diarrheal stools from inpatients.

[In vitro study of the bacteriostatic and bactericidal activity of meropenem against strains of Pseudomonas aeruginosa multiresistant to antibiotics]

Meropenem is a new dehydropeptidase stable carbapenem which has an in vitro bacteriostatic activity superior to imipenem against Pseudomonas aeruginosa. Minimal inhibitory concentrations of meropenem (MEM) and imipenem (IPM) were determined on twelve strains: two were genetically characterized reference strains and ten isolated from patients. Killing curves were performed for MEM used at 1,2 and 4 fold the MIC and 32 mg/l; survivors were counted at baseline and after 5 and 24 hours of incubation by spiral plating. Five strains were susceptible to MEM and IPM; five were intermediate and two resistant to MEM; these seven strains were resistant to IPM. A weak bactericidal effect was obtained after 5 h at each concentration. Only one strain achieved a 3 log 10 reduction after 5 h at 2 x MIC. A regrowth of all the strains tested was observed after 24 h.

[Epidemiology of Clostridium difficile nosocomial infections]

Clostridium difficile accounts for 15-25% of cases of antibiotic-associated diarrhea (AAD) and for virtually all cases of antibiotic-associated pseudo-membranous colitis (PMC). This anaerobic bacterium is also carried in the gastro-intestinal tract of less than 3% of the normal adult population and can be isolated from the feces of 50-70% asymptomatic neonates. Since recent years, C. difficile has been identified as the leading cause of nosocomial diarrhea in adults. Pathogenesis relies on a disruption of the normal bacteria flora of the colon, a colonization with C. difficile and the release of toxins that cause mucosal damage and inflammation. Incidence of C. difficile intestinal disorders varies between 1 to 30 per thousand patient admissions. Risk factors for C. difficile-associated diarrhea include antimicrobial therapy, older age (> 65 years), intensive care, nasogastric tube, anti-acid use, and length of hospital stay. Nosocomial transmission of C. difficile via orofecal route occurs in 3-30% of total patient admissions but it often remains asymptomatic. Environmental contamination and carriage of the organism on the hands of hospital staff are common. Measures that are recommended to reduce cross-infection rely on an accurate and rapid diagnosis, implementation of enteric isolation, use of disposable gloves, hand washing with a suitable disinfectant (e.g. chlorhexidine) and daily environmental disinfection. C. difficile is a common cause of infectious diarrhea and should be therefore systematically investigated in patients with nosocomial diarrhea.

Risk factors for isolation of Streptococcus pneumoniae with decreased susceptibility to penicillin G from patients infected with human immunodeficiency virus

We conducted a retrospective study of all hospitalized human immunodeficiency virus (HIV)-infected patients from whom a strain of Streptococcus pneumoniae was isolated (n = 45) between January 1992 and September 1994, in order to determine the clinical manifestations and outcome of and risk factors for infection by S. pneumoniae with decreased susceptibility to penicillin G. Such strains were isolated from 14 patients (31%), of whom 8 had pneumonia, 2 had bronchial superinfection, 2 had sinusitis, and 2 were colonized. All infected patients made a clinical recovery regardless of the MIC of the isolate. Indexes of HIV disease stage (CD4+ cell count and p24 antigenemia), antiretroviral treatment, and hospital admission in the previous 3 months did not influence the susceptibility of the isolates. For HIV-infected patients, treatment with antibacterial agents--particularly trimethoprim-sulfamethoxazole--in the previous 3 months is associated with an increased risk for isolation of S. pneumoniae with decreased susceptibility to penicillin G (relative risk, 5.0; 95% confidence interval, 1.9-13.3).

[Acid-alcohol-resistant bacilli detected by microscopic analysis of exhaled air from HIV-infected patients: tuberculosis or mycobacteriosis?]

OBJECTIVES

The incidence of atypical mycobacterial infections has increased with the AIDS epidemic. To present, microscopic examinations of airway specimens positive for acid-fast bacteria were highly suggestive of tuberculosis. However, since the AIDS epidemic, certain authors have reported an increase in Mycobacterium avium intracellulare found in respiratory specimens. The aim of this work was to determine what factors might distinguish between these two infections revealed discovery of an acid-fact bacilli.

METHODS

Hospital files of all HIV seropositive patients seen between November 1992 and March 1995 and with at least one airway specimen positive for acid-fast bacilli were studied retrospectively.

RESULTS

Mycobacterium tuberculosis was isolated in 19 patients, Mycobacterium avium intracellulare in 8 and culosis and M. avium intracellulare. There was no difference for age, sex, geographical origin, transmission mode, antigen positivity, radiologic findings or clinical signs between patients with the different types of mycobacterium. The CD4 count was however significantly lower in patients with an atypical mycobacteriosis (14.5/mm3) than in patients with tuberculosis (91.7 +/- 83.7) (p = 0.004).

CONCLUSION

These findings show that in HIV-infected patients with a CD4 count under 100/mm3, the presence of acid-fact bacilli can indicate either M. tuberculosis or M. avium intracellulare. Combined anti-tuberculosis and antimycobacteriosis therapy thus would appear to be justified until the germ can be identified.

Bactericidal effect of sparfloxacin alone and in combination with amoxicillin against Streptococcus pneumoniae as determined by kill-kinetic studies

Ten clinical isolates of Streptococcus pneumoniae (six intermediately penicillin-sensitive, one penicillin-resistant and three penicillin-sensitive strains) were studied by kill-kinetic experiments using sparfloxacin alone and in combination with amoxicillin. Equipotent doses of the antibiotics (1x, 2x and 4x the MIC) were used in the kill-kinetic studies. Sparfloxacin had a moderate bactericidal potential at 4x MIC after 5h and the combination with amoxicillin did not significantly increase its bactericidal activity. The clinical significance of these findings warrants further studies in vivo.

Decreased transmission of Enterobacteriaceae with extended-spectrum beta-lactamases in an intensive care unit by nursing reorganization

In our gastrointestinal surgical intensive care unit (SICU), the large number of patients with multiple enterostomies enhances the risk of nosocomial transmission of gut extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBLE) by health care workers. A control study performed in our SICU from June-August 1992 showed an ESBLE gut colonization rate of 70%. To reduce this rate, nursing procedures were intensified or modified, particularly handwashing, single-use equipment and waste control. To test the efficiency of these procedures, 64 patients hospitalized for more than two days from September 1992-March 1993 were screened for gut acquisition of ESBLE. Rectal samples were taken within 48 h after admission and then weekly. After nursing reorganization, the ESBLE colonization rate dropped significantly to 40% (P < 0.001). Twenty patients (31.7%) acquired a gut ESBLE, after a mean of 24.3 +/- 13.7 days. Each patient was colonized with one, two or three ESBLE (Klebsiella pneumoniae, Escherichia coli and Enterobacter aerogenes). Baseline characteristics of the 20 colonized and 39 non-colonized patients showed no significant difference (Student's t-test, P > 0.05). The nursing workload, estimated as a omega index, was greater in the colonized group (P < 0.001). These findings show that strict observance of nursing procedures can significantly reduce ESBLE acquisition in a high-risk surgical unit.

Serum anti-p24 antibody concentration has a predictive value on the decrease of CD4 lymphocyte count higher than acid-dissociated p24 antigen

We studied the prognostic value on the decrease of CD4 lymphocyte count of anti-p24 antibody (ab) titer and compared this value with that of polyclonal and monoclonal p24 (ag) titer before and after immune complex dissociation (ICD); 53 human immunodeficiency virus (HIV)-infected patients having CD4+ counts above 400/mm3 when first examined were followed up over a 3-year period including at least four visits; HIV disease progressors (n = 18) were defined as having CD4+ counts below 200/mm3 and non-progressors (n = 35) as having CD4+ counts still above 400/mm3 at the end of follow-up. Sera were collected at each visit and assayed for p24 ag with and without ICD and for anti-p24 ab titer. The mean anti-p24 ab titer of progressors and of non-progressors at entry was significantly different. A threshold of anti-p24 ab titer indicating a HIV progression was determined at 1/300. The proportion of individuals with an anti-p24 ab titer lower than 1/300 at least once during the study period was 34% in non-progressors and 94% in progressors. The difference between progressors and non-progressors at entry was significant with monoclonal p24 ag without ICD and more significant with monoclonal p24 ag after ICD. The marker having the highest predictive value was the anti-p24 ab titer, then monoclonal p24 ag with ICD, then polyclonal p24 ag with ICD. Anti-p24 ab is an earlier and stronger marker of the decrease of CD4 lymphocyte count than p24 ag even after ICD.