High specificity of line-immunoassay based algorithms for recent HIV-1 infection independent of viral subtype and stage of disease.

BACKGROUND: Serologic testing algorithms for recent HIV seroconversion (STARHS) provide important information for HIV surveillance. We have shown that a patient's antibody reaction in a confirmatory line immunoassay (INNO-LIA HIV I/II Score, Innogenetics) provides information on the duration of infection. Here, we sought to further investigate the diagnostic specificity of various Inno-Lia algorithms and to identify factors affecting it. METHODS: Plasma samples of 714 selected patients of the Swiss HIV Cohort Study infected for longer than 12 months and representing all viral clades and stages of chronic HIV-1 infection were tested blindly by Inno-Lia and classified as either incident (up to 12 m) or older infection by 24 different algorithms. Of the total, 524 patients received HAART, 308 had HIV-1 RNA below 50 copies/mL, and 620 were infected by a HIV-1 non-B clade. Using logistic regression analysis we evaluated factors that might affect the specificity of these algorithms. RESULTS: HIV-1 RNA < 50 copies/mL was associated with significantly lower reactivity to all five HIV-1 antigens of the Inno-Lia and impaired specificity of most algorithms. Among 412 patients either untreated or with HIV-1 RNA ≥ 50 copies/mL despite HAART, the median specificity of the algorithms was 96.5% (range 92.0-100%). The only factor that significantly promoted false-incident results in this group was age, with false-incident results increasing by a few percent per additional year. HIV-1 clade, HIV-1 RNA, CD4 percentage, sex, disease stage, and testing modalities exhibited no significance. Results were similar among 190 untreated patients. CONCLUSIONS: The specificity of most Inno-Lia algorithms was high and not affected by HIV-1 variability, advanced disease and other factors promoting false-recent results in other STARHS. Specificity should be good in any group of untreated HIV-1 patients.

Application and evaluation of double digest selective label (DDSL) typing technique for Pseudomonas aeruginosa hospital isolates.

This study describes the application and evaluation of a recently developed fast bacterial typing technique (double digest selective label - DDSL) for hospital isolates of Pseudomonas aeruginosa. The protocol was based on a simultaneous double digestion/labelling reaction which was performed in a single reaction tube. After agarose gel separation selectively tagged restriction fragments were transferred using deonised water to a nylon membrane and visualized by a colour reaction. Starting from overnight culture, turn around time using this technique was only 8 h. The DDSL typing technique was applied for 77 hospital isolates. Among them 63 isolates were also typed by PFGE and the typing results were compared with those of DDSL. In conclusion, both techniques discriminated bacterial isolates into the same major clusters. DDSL proved to be as discriminatory as PFGE but much faster and easier to set up in a standard microbiological laboratory.

Vancomycin prophylaxis of experimental Streptococcus sanguis. Inhibition of bacterial adherence rather than bacterial killing.

Using a strain of Streptococcus sanguis tolerant to vancomycin to infect aortic vegetations in rats, we found that prophylactic intravenous vancomycin given 30 min before bacterial challenge decreased the incidence of endocarditis from 88 to 8% (P less than 10(-5)). Because peak vancomycin serum levels were below the minimal bactericidal concentration, mechanisms of protection other than bacterial killing were investigated. S. sanguis were incubated with inhibitory concentration of vancomycin (50 microgram/ml) for 10 h and washed. 85% of rats (73/86) inoculated with control bacteria developed endocarditis, whereas only 42% (33/78) of those inoculated with vancomycin-exposed bacteria did so (P less than 10(-5)). When rats were killed 30 min after bacterial challenge, S. sanguis were detected by culture of the vegetations in 44% of rats injected with control bacteria, but in only 13% of those challenged with vancomycin-exposed bacteria (P less than 0.03). Enhanced clearance of vancomycin-exposed streptococci was not responsible for this protection because blood cultures showed no difference in the level and duration of bacteremia after injection of control or vancomycin-exposed S. sanguis. Moreover, this protection was not abolished in neutropenic rats injected with vancomycin-exposed bacteria, despite more prolonged bacteremia. These results suggest that vancomycin exerted its protection by lowering adherence of tolerant S. sanguis to vegetations rather than through bactericidal activity or enhanced clearance of bacteria by phagocytic cells. In the choice of antibiotics for prophylaxis of endocarditis, reduction of bacterial adhesion may be a criterion as important as bacterial killing.

Blood samples drawn for culture as a surrogate marker for case-mix adjustment of hospital antibiotic use.

Hospital antibiotic consumption is generally adjusted to occupancy. This study hypothesised that the number of blood culture samples could be a surrogate marker for case-mix adjustment. Antibiotic consumption was compared over 16 consecutive trimesters in one medical ward in terms of patient-days or blood culture samples. Compared with patient-days, measurement adjusted to blood culture samples detected three trimesters with an unusually high consumption, and one trimester with consumption falsely classified as high because of a high incidence of infections. Blood culture numbers enabled easy and accurate identification of periods with a drift in antibiotic consumption ina medical ward.

Evaluation of three chromogenic media (MRSA-ID, MRSA-Select and CHROMagar MRSA) and ORSAB for surveillance cultures of methicillin-resistant Staphylococcus aureus.

Screening specimens were homogenised in saline 0.9% w/v before either direct inoculation or following enrichment in broth on three chromogenic media (MRSA-ID, CHROMagar MRSA and MRSA Select) and ORSAB medium for the detection of methicillin-resistant Staphylococcus aureus (MRSA). In total, 102 of 466 specimens yielded MRSA on at least one medium. After incubation for 16-18 h, the sensitivity was 51%, 59%, 47% and 65% on MRSA-ID, CHROMagar MRSA, ORSAB and MRSA Select, respectively, compared with 82%, 75%, 67% and 80%, respectively, after 42 h, and 93%, 95%, 79% and not tested, respectively, following broth enrichment. There were significantly more MRSA colonies on MRSA-Select after 16-18 h than on ORSAB or MRSA ID (p 0.001 and 0.0022, respectively), whereas there were more MRSA colonies after 42 h on MRSA-ID and MRSA-Select than on ORSAB (p 0.0004 and 0.012, respectively). The specificity of the media for identifying MRSA based on the colour of colonies after incubation for 16-18 h was 100%, 99%, 99% and 100%, respectively, compared with 98%, 97%, 98% and 98%, respectively, after 42 h, and 100%, 99%, 100% and not tested, respectively, following broth enrichment. The speed of detection (mean time to report a positive result) was 1.65, 1.72, 2.31 and 1.35 days, respectively. For each of the three media tested following enrichment, the use of an enrichment broth increased the detection rate of MRSA by 16-24%.

[Infective endocarditis and outpatient practice]. / L'endocardite en pratique ambulatoire.

The incidence of infectious endocarditis is fairly stable over the past decades. It is estimated at roughly 3-4 case per patient-year. However, as a consequence of medical progress, Staphylococcus aureus endocarditis has become more prevalent. This is particularly true for health-care associated endocarditis, especially in iv-drug abusers or hemodialysis patients. Mortality (15-20% of patients in the last series) remains high. About 50% of patients undergo surgical treatment, whereas outpatient therapy is more and more frequent for highly selected subgroups of patients without complications and infected with low-risk organims. The present paper reviews in detail the epidemiology of infective endocarditis and discuss in detail the different out-patients therapies.

Influence of bacille Calmette-Guérin vaccination on size of tuberculin skin test reaction: to what size?

BACKGROUND: Previous bacillus Calmette-Guerin (BCG) vaccination can confound the results of a tuberculin skin test (TST). We sought to determine a cutoff diameter of TST induration beyond which the influence of BCG vaccination was negligible in evaluating potential Mycobacterium tuberculosis infection in a population of health care workers with a high vaccination rate and low incidence of tuberculosis. METHODS: From 1991 through 1998, all new employees at the University Hospital of Lausanne, Switzerland, underwent a 2-step TST at entry visit. We also gathered information on demographic characteristics, along with factors commonly associated with tuberculin positivity, including previous BCG vaccination, history of latent M. tuberculosis infection, and predictors for M. tuberculosis infection. RESULTS: Among the 5117 investigated subjects, we found that influence of BCG vaccination on TST results varied across categories of age (likelihood ratio test, 0.0001). Prior BCG vaccination had a strong influence on skin test results of

Water disinfection with ozone, copper and silver ions, and temperature increase to control Legionella: seven years of experience in a university teaching hospital.

The efficacy of ozonation, copper-silver ionization and increased temperature in controlling Legionella spp. in the hot water distribution networks of a university hospital was evaluated. Two separate water distribution networks were studied; network 1 which supplies the surgical intensive care units, and network 2 which supplies the medical intensive care units and the emergency room. Network 1 has been disinfected by ozonation since 1995, and network 2 has been disinfected by ionisation since 1999. The hot water temperature was increased from 50 to 65 degrees C in 1998 and 2000 in networks 1 and 2, respectively. Water samples and swabs of the water outlets were cultured for Legionella spp. between four and six times each year, providing data before and after implementation of the disinfection procedures. There was no significant difference in the proportion of samples positive for Legionella spp. after ozonation in network 1 or after ionization in network 2. In both networks, there was a significant reduction in legionella isolates after increasing the hot water temperature to 65 degrees C. Maintaining the hot water temperature above 50 degrees C throughout both networks proved to be the most effective control measure in our hospital.

Complications of Staphylococcus aureus bacteremia. Occurrence in patients undergoing long-term hemodialysis.

Since staphylococcus aureus bacteremia continues to be a common occurrence in patients with arteriovenous fistulas who are undergoing long-term hemodialysis, the complications and outcome of 37 episodes of bacteremia were examined. Systemic complications included pulmonary emboli, empyema, persistent bacteremia, and endocarditis. Such events were rarely life threatening--three of the 34 episodes involving patients without severe concurrent medical problems resulted in death. Local complications at the fistula site were common; however, thrombosis, hemorrhage, impending rupture, and persistent bacteremia caused loss of fistula in 13 of the 22 episodes seen with fistula inflammation. Results of this study demonstrate that, although loss of vascular access was an important problem, particularly in patients with prosthetic grafts, patients with S aureus bacteremia who were undergoing long-term hemodialysis had a favorable prognosis for survival, particularly when they were compared with other patients not undergoing hemodialysis.

Guillain-Barré syndrome following Campylobacter jejuni enteritis. Report of three cases and review of the literature.

We describe three cases of Guillain-Barré syndrome (GBS) associated with Campylobacter jejuni enteritis and review the data from eight other cases described in detail in the literature. The recent recognition of this association is probably due to improved stool culture technique. In comparison with GBS associated with respiratory infections, the delay between the first symptoms of infection and the development of GBS is somewhat longer, an observation in accordance with GBS associated with gastrointestinal symptoms of unidentified etiology. The clinical picture and the outcome do not seem to differ from those of GBS associated with other disorders. Campylobacter jejuni appears to be a pathogen capable of triggering GBS and will probably become increasingly recognized if appropriate culture and serologic tests are performed.

Cardiobacterium hominis endocarditis manifesting as bacterial meningitis.

Cardiobacterium hominis is a rare cause of endocarditis, and infection caused by this organism has not been described outside the vascular system. A patient with a congenital bicuspid aortic valve was initially seen with C hominis bacterial meningitis. Septic emboli from an underlying endocarditis were probably the source of the infection.

Campylobacter fetus subspecies fetus bacteremia.

Eight patients with Campylobacter fetus bacteremia, six of them with serious underlying diseases, were seen in a two-year period. Besides fever, which was observed in all cases, the most frequent clinical manifestation was lower extremity phlebitis and cellulitis (four patients). In one of these patients, it had the peculiar aspect of bilateral pretibial cellulitis. One patient had vertebral osteomyelitis, a complication, to our knowledge, not yet described. Two patients, both with advanced underlying diseases, died. The five patients who completed a two- to three-week course of erythromycin gluceptate, all had initial clinical improvement. However, one patient suffered a relapse at the end of treatment, and progression of vertebral osteomyelitis while on erythromycin therapy was observed in another patient. These clinical and bacteriologic failures occurred despite the in vitro sensitivity to erythromycin of the two strains. This suggests that erythromycin might not be adequate therapy for C fetus septicemia.

Spare post-exposure prophylaxis with round-the-clock HIV testing of the source patient.

After occupational exposures, immediate HIV testing of source patients may avoid the unnecessary use of post-exposure prophylaxis (PEP). Two time periods were compared. Before the availability of 24 h a day immediate testing, PEP was initiated after 12.6% of exposures, compared with 3.7% during the second period. The adjusted relative odds ratio of PEP during the second compared with the first period, was 0.23. The availability of immediate HIV testing limits unnecessary occupational PEP.

Transmission of Pneumocystis carinii from AIDS patients to other immunosuppressed patients: a cluster of Pneumocystis carinii pneumonia in renal transplant recipients.

Five renal transplant recipients developed Pneumocystis carinii pneumonia (PCP) over a 22-month period, while no cases had been observed over a 5-year period in 114 transplanted patients treated with the same immunosuppressive protocol. All patients were HIV-negative, and no modification in diagnostic techniques for P. carinii could account for this observation. All five patients developed PCP within 2 months of an acute graft rejection episode. All of them attended the same outpatient facility as AIDS patients attending the hospital, where they shared the waiting and treatment rooms. Comparison of cases with matched controls was possible in three instances and revealed that the cases had had more outpatient clinic encounters with AIDS patients who had presented, or subsequently developed, PCP. This observation suggests that AIDS patients developing PCP may transmit the infection to other immunosuppressed patients.

Changes in use of antiretroviral therapy in regions of Europe over time. EuroSIDA Study Group.

OBJECTIVES: To analyse use of antiretroviral therapy within Europe between 1994 and 1997. DESIGN: From September 1994, the EuroSIDA study (cohorts I-III) has prospectively followed unselected HIV-infected patients from 50 clinical centres in 17 European countries (total, 7230). METHODS: Patients under follow-up at half-year intervals from September 1994 (n=2871) to September 1997 (n=3682) were classified according to number of drugs currently used (none, one, two, three, four or more). Use of antiretroviral therapy was stratified by CD4 cell count (< 200 versus > or = 200 x 10(6)/l) and by region of Europe (south, central, or north). Frequency data were compared by chi2 test and logistic regression modelling. RESULTS: The proportion of patients on antiretroviral monotherapy diminished over time (1994, 42%; 1997, 3%), as did the proportion of patients without therapy (from 37 to 9%). Over time, the proportion of patients on triple (from 2 to 55%) and quadruple (from 0 to 9%) therapy increased, whereas use of dual therapy peaked in 1996 and subsequently fell. In the three regions of Europe, changes in use of antiretroviral therapy differed substantially. However, as of September 1997, only minor differences persisted. The proportion of patients on dual, triple, and quadruple therapy were as follow: south, 33, 52 and 5%, respectively; central, 23, 55 and 14%, respectively; north, 16, 59 and 10%, respectively. In September 1997, odds for use of three or more drugs including at least one protease inhibitor did not differ significantly between regions. CONCLUSIONS: Use of antiretroviral therapy in Europe has changed dramatically towards combination treatment in the last few years. Regional differences in use of antiretroviral therapy have decreased, and by September 1997 only minor differences remained. Antiretroviral therapy with three or more drugs and use of protease inhibitors has become more common in all regions of Europe.

Genetic diversity of Pneumocystis carinii in HIV-positive and -negative patients as revealed by PCR-SSCP typing.

OBJECTIVE: To describe the epidemiology of severe Pneumocystis carinii pneumonia (PCP) in HIV-infected and non HIV-infected patients. METHODS: Bronchoalveolar lavage specimens from 212 European patients with PCP were typed using PCR--single strand conformation polymorphism analysis of four genomic regions of P. carinii f. sp. hominis. Demographic and clinical information was obtained from all patients. RESULTS: Twenty-three per cent of the patients were presumably infected with a single P. c. hominis type. The other patients presented with two (50%) or more (27%) types. Thirty-five genetically stable and ubiquitous P. c. hominis types were found. Their frequency ranged from 0.4% to 10% of all isolates, and up to 15% of those from a given hospital. There was no significant association between the P. c. hominis type or number of co-infecting types per patient and geographical location, year of collection, sex, age, or HIV status. No more than three patients infected with the same type were observed in the same hospital within the same 6 month period, and no epidemiological link between the cases was found. CONCLUSIONS: The broad diversity of types observed seems to indicate that multiple sources of the pathogen co-exist. There was no evidence that in our study population inter-human transmission played a significant role in the epidemiology of P. carinii.

Changes in the cause of death among HIV positive subjects across Europe: results from the EuroSIDA study.

OBJECTIVES: The causes of death among HIV-positive patients may have changed since the introduction of highly active antiretroviral therapy (HAART). We investigated these changes, patients who died without an AIDS diagnosis and factors relating to pre-AIDS deaths. METHODS: Analyses of 1826 deaths among EuroSIDA patients, an observational study of 8556 patients. Incidence rates of pre-AIDS deaths were compared to overall rates. Factors relating to pre-AIDS deaths were identified using Cox regression. RESULTS: Death rates declined from 15.6 to 2.7 per 100 person-years of follow-up (PYFU) between 1994 and 2001. Pre-AIDS incidence declined from 2.4 to 1.1 per 100 PYFU. The ratio of overall to pre-AIDS deaths peaked in 1996 at 8.4 and dropped to < 3 after 1998. The adjusted odds of dying following one AIDS defining event (ADE) increased yearly (odds ratio, 1.53; P < 0.001), conversely the odds of dying following three or more ADE decreased yearly (odds ratio, 0.79; P < 0.001). The proportion of deaths that followed an HIV-related disease decreased by 23% annually; in contrast there was a 32% yearly increase in the proportion of deaths due to known causes other than HIV-related or suicides. Injecting drug users (IDU) were significantly more likely to die before an ADE than homosexuals (relative hazard, 2.97; P < 0.0001) and patients from northern/eastern Europe (relative hazard, 2.01; P < 0.0001) were more likely to die pre-AIDS than southern patients. CONCLUSIONS: The proportion of pre-AIDS deaths increased from 1994 to 2001; however, the incidence of pre-AIDS deaths and deaths overall declined. IDU and subjects from northern/eastern Europe had an increased risk of pre-AIDS death. HIV-positive patients live longer therefore it is essential to continue to monitor all causes of mortality to identify changes.

Hyperlactatemia and antiretroviral therapy: the Swiss HIV Cohort Study.

The prevalence, clinical presentation, and risk factors for hyperlactatemia among patients receiving antiretroviral therapy was determined during a 1-month period for patients in the Swiss HIV Cohort Study. Overall, 73 (8.3%) of 880 patients presented an increase in serum lactate of >1.1 times the upper normal limit (UNL). For 9 patients (1%), lactate elevation was moderate or severe (>2.2 times the UNL). Patients who presented with hyperlactatemia were more likely to be receiving stavudine with or without didanosine (odds ratio, 2.7; 95% confidence interval, 1.5-4.8), as compared with patients who received zidovudine-based regimens. The risk increased with increasing time receiving stavudine with or without didanosine. The association between hyperlactatemia and stavudine with or without didanosine was not biased by these medications being more recently available and, therefore, being given preferentially to patients who had prolonged use of nucleoside analog reverse-transcriptase inhibitors. Hyperlactatemia was associated with lipoatrophy, hyperlipidemia, and hyperglycemia. Age, sex, or stage of infection with human immunodeficiency virus were not predictive of hyperlactatemia. Determination of lactate levels may prove useful in the screening for mitochondrial toxicity.

Community-acquired pneumonia. A prospective outpatient study.

We initiated a prospective study with a group of practitioners to assess the etiology, clinical presentation, and outcome of community-acquired pneumonia in patients diagnosed in the outpatient setting. All patients with signs and symptoms suggestive of pneumonia and an infiltrate on chest X-ray underwent an extensive standard workup and were followed over 4 weeks. Over a 4-year period, 184 patients were eligible, of whom 170 (age range, 15-96 yr; median, 43 yr) were included and analyzed. In 78 (46%), no etiologic agent could be demonstrated. In the remaining 92 patients, 107 etiologic agents were implicated: 43 were due to "pyogenic" bacteria (39 Streptococcus pneumoniae, 3 Haemophilus spp., 1 Streptococcus spp.), 39 were due to "atypical" bacteria (24 Mycoplasma pneumoniae, 9 Chlamydia pneumoniae, 4 Coxiella burnetii, 2 Legionella spp.), and 25 were due to viruses (20 influenza viruses and 5 other respiratory viruses). There were only a few statistically significant clinical differences between the different etiologic categories (higher age and comorbidities in viral or in episodes of undetermined etiology, higher neutrophil counts in "pyogenic" episodes, more frequent bilateral and interstitial infiltrates in viral episodes). There were 2 deaths, both in patients with advanced age (83 and 86 years old), and several comorbidities. Only 14 patients (8.2%) required hospitalization. In 6 patients (3.4%), the pneumonia episode uncovered a local neoplasia. This study shows that most cases of community-acquired pneumonia have a favorable outcome and can be successfully managed in an outpatient setting. Moreover, in the absence of rapid and reliable clinical or laboratory tests to establish a definite etiologic diagnosis at presentation, the spectrum of the etiologic agents suggest that initial antibiotic therapy should cover both S. pneumoniae and atypical bacteria, as well as possible influenza viruses during the epidemic season.

Bacteremia due to viridans streptococci in neutropenic patients: a review.

Viridans streptococci have long been considered, with the exception of the ability to cause endocarditis, as minor pathogenic agents. More recently, however, these bacteria have become a major concern in neutropenic patients undergoing a chemotherapeutic treatment. In this high-risk population, they can be responsible for up to 39% of bacteremia cases and are the most frequent cause of this type of infection. The most frequently isolated species in blood cultures are Streptococcus mitis and Streptococcus sanguis II. Viridans streptococcus bacteremia can be accompanied by serious complications, like adult respiratory distress syndrome (ARDS) (3% to 33%), shock (7% to 18%) or endocarditis (7% to 8%). Mortality rates range from 6% to 30%. Case-control studies have identified the following risk factors: severe neutropenia (< 100 neutrophils/mm3), prophylactic antibiotic treatments with quinolone or co-trimoxazole, absence of intravenous antibiotics at the time of bacteremia, high doses of cytosine arabinoside, oropharyngeal mucositis, and heavy colonization by viridans streptococci. The introduction of penicillin in prophylactic antibiotic treatments has reduced the incidence of these infections, but the long-term use of penicillin could be compromised by the emergence of resistant strains.