Clostridium difficile infection in Europe: a hospital-based survey

BACKGROUND

Little is known about the extent of Clostridium difficile infection in Europe. Our aim was to obtain a more complete overview of C difficile infection in Europe and build capacity for diagnosis and surveillance.

METHODS

We set up a network of 106 laboratories in 34 European countries. In November, 2008, one to six hospitals per country, relative to population size, tested stool samples of patients with suspected C difficile infection or diarrhoea that developed 3 or more days after hospital admission. A case was defined when, subsequently, toxins were identified in stool samples. Detailed clinical data and stool isolates were collected for the first ten cases per hospital. After 3 months, clinical data were followed up.

FINDINGS

The incidence of C difficile infection varied across hospitals (weighted mean 4·1 per 10,000 patient-days per hospital, range 0·0-36·3). Detailed information was obtained for 509 patients. For 389 of these patients, isolates were available for characterisation. 65 different PCR ribotypes were identified, of which 014/020 (61 patients [16%]), 001 (37 [9%]), and 078 (31 [8%]) were the most prevalent. The prevalence of PCR-ribotype 027 was 5%. Most patients had a previously identified risk profile of old age, comorbidity, and recent antibiotic use. At follow up, 101 (22%) of 455 patients had died, and C difficile infection played a part in 40 (40%) of deaths. After adjustment for potential confounders, an age of 65 years or older (adjusted odds ratio 3·26, 95% CI 1·08-9·78; p=0·026), and infection by PCR-ribotypes 018 (6·19, 1·28-29·81; p=0·023) and 056 (13·01; 1·14-148·26; p=0·039) were significantly associated with complicated disease outcome.

INTERPRETATION

PCR ribotypes other than 027 are prevalent in European hospitals. The data emphasise the importance of multicountry surveillance to detect and control C difficile infection in Europe.

FUNDING

European Centre for Disease Prevention and Control.

Sexual transmission and propagation of SIV and HIV in resting and activated CD4+ T cells

In sexual transmission of simian immunodeficiency virus, and early and later stages of human immunodeficiency virus-type 1 (HIV-1) infection, both viruses were found to replicate predominantly in CD4(+) T cells at the portal of entry and in lymphoid tissues. Infection was propagated not only in activated and proliferating T cells but also, surprisingly, in resting T cells. The infected proliferating cells correspond to the short-lived population that produces the bulk of HIV-1. Most of the HIV-1-infected resting T cells persisted after antiretroviral therapy. Latently and chronically infected cells that may be derived from this population pose challenges to eradicating infection and developing an effective vaccine.

Biphasic kinetics of peripheral blood T cells after triple combination therapy in HIV-1 infection: a composite of redistribution and proliferation

The origin of CD4+ T cells reappearing in the blood following antiretroviral therapy in human immunodeficiency virus type-1 (HIV-1) infection is still controversial. Here we show, using mathematical modeling, that redistribution of T cells to the blood can explain the striking correlation between the initial CD4+ and CD8+ memory T-cell repopulation and the observation that 3 weeks after the start of treatment memory CD4+ T-cell numbers reach a plateau. The increase in CD4+ T cells following therapy most likely is a composite of initial redistribution, accompanied by a continuous slow repopulation with newly produced naive T cells.

Emergence of Clostridium difficile infection due to a new hypervirulent strain, polymerase chain reaction ribotype 078

BACKGROUND

Since 2005, an increase in the prevalence of Clostridium difficile infection (CDI) due to polymerase chain reaction ribotype 078 has been noticed in The Netherlands. This strain has also been identified as the predominant strain in pigs and calves.

METHODS

CDI caused by type 078 was studied in relation to CDI caused by the hypervirulent type 027 and by types other than 027 and 078. Human and porcine isolates were further investigated and characterized by multilocus variable number tandem repeat analysis.

RESULTS

From February 2005 through February 2008, the incidence of type 078 among isolates obtained from 1687 patients increased from 3% to 13%. Compared with patients infected with type 027, patients infected with type 078 were younger (67.4 vs. 73.5 years; P < .01) and more frequently had community-associated disease (17.5% vs. 6.7%; odds ratio, 2.98; 95% confidence interval, 2.11-8.02); rates of severe diarrhea (38.9% vs. 40.0%) and attributable mortality (3.8% vs. 4.0%) were similar in both groups. Compared with patients infected with other types, patients infected with type 078 more frequently received fluoroquinolone therapy (29.4% vs. 19.8%; odds ratio, 2.17; 95% confidence interval, 1.06-4.44). Type 078 isolates contained genes for toxin A, toxin B, binary toxin, and a 39-base pair deletion in toxin regulator gene (tcdC), as well as a point mutation at position 184, resulting in a stop codon. Multilocus variable number tandem repeat analysis of 54 human and 11 porcine isolates revealed 4 clonal complexes containing both porcine and human isolates.

CONCLUSIONS

CDI due to type 078 and CDI due to type 027 present with similar severity, but CDI due to type 078 affects a younger population and is more frequently community associated. C. difficile type 078 isolates from humans and pigs are highly genetically related.

Kinetics of response in lymphoid tissues to antiretroviral therapy of HIV-1 infection

In lymphoid tissue, where human immunodeficiency virus-type 1 (HIV-1) is produced and stored, three-drug treatment with viral protease and reverse transcriptase inhibitors markedly reduced viral burden. This was shown by in situ hybridization and computerized quantitative analysis of serial tonsil biopsies from previously untreated adults. The frequency of productive mononuclear cells (MNCs) initially diminished with a half-life of about 1 day. Surprisingly, the amount of HIV-1 RNA in virus trapped on follicular dendritic cells (FDCs) decreased almost as quickly. After 24 weeks, MNCs with very few copies of HIV-1 RNA per cell were still detectable, as was proviral DNA; however, the amount of FDC-associated virus decreased by >/=3.4 log units. Thus, 6 months of potent therapy controlled active replication and cleared >99.9 percent of virus from the secondary lymphoid tissue reservoir.

Infection control measures to limit the spread of Clostridium difficile

Clostridium difficile-associated diarrhoea (CDAD) presents mainly as a nosocomial infection, usually after antimicrobial therapy. Many outbreaks have been attributed to C. difficile, some due to a new hyper-virulent strain that may cause more severe disease and a worse patient outcome. As a result of CDAD, large numbers of C. difficile spores may be excreted by affected patients. Spores then survive for months in the environment; they cannot be destroyed by standard alcohol-based hand disinfection, and persist despite usual environmental cleaning agents. All these factors increase the risk of C. difficile transmission. Once CDAD is diagnosed in a patient, immediate implementation of appropriate infection control measures is mandatory in order to prevent further spread within the hospital. The quality and quantity of antibiotic prescribing should be reviewed to minimise the selective pressure for CDAD. This article provides a review of the literature that can be used for evidence-based guidelines to limit the spread of C. difficile. These include early diagnosis of CDAD, surveillance of CDAD cases, education of staff, appropriate use of isolation precautions, hand hygiene, protective clothing, environmental cleaning and cleaning of medical equipment, good antibiotic stewardship, and specific measures during outbreaks. Existing local protocols and practices for the control of C. difficile should be carefully reviewed and modified if necessary.

Global outbreak of severe Mycobacterium chimaera disease after cardiac surgery: a molecular epidemiological study

BACKGROUND

Since 2013, over 100 cases of Mycobacterium chimaera prosthetic valve endocarditis and disseminated disease were notified in Europe and the USA, linked to contaminated heater-cooler units (HCUs) used during cardiac surgery. We did a molecular epidemiological investigation to establish the source of these patients' disease.

METHODS

We included 24 M chimaera isolates from 21 cardiac surgery-related patients in Switzerland, Germany, the Netherlands, and the UK, 218 M chimaera isolates from various types of HCUs in hospitals, from LivaNova (formerly Sorin; London, UK) and Maquet (Rastatt, Germany) brand HCU production sites, and unrelated environmental sources and patients, as well as eight Mycobacterium intracellulare isolates. Isolates were analysed by next-generation whole-genome sequencing using Illumina and Pacific Biosciences technologies, and compared with published M chimaera genomes.

FINDINGS

Phylogenetic analysis based on whole-genome sequencing of 250 isolates revealed two major M chimaera groups. Cardiac surgery-related patient isolates were all classified into group 1, in which all, except one, formed a distinct subgroup. This subgroup also comprised isolates from 11 cardiac surgery-related patients reported from the USA, most isolates from LivaNova HCUs, and one from their production site. Isolates from other HCUs and unrelated patients were more widely distributed in the phylogenetic tree.

INTERPRETATION

HCU contamination with M chimaera at the LivaNova factory seems a likely source for cardiothoracic surgery-related severe M chimaera infections diagnosed in Switzerland, Germany, the Netherlands, the UK, the USA, and Australia. Protective measures and heightened clinician awareness are essential to guarantee patient safety.

FUNDING

Partly funded by the EU Horizon 2020 programme, its FP7 programme, the German Center for Infection Research (DZIF), the Swiss National Science Foundation, the Swiss Federal Office of Public Health, and National Institute of Health Research Oxford Health Protection Research Units on Healthcare Associated Infection and Antimicrobial Resistance.

Pertussis disease burden in the household: how to protect young infants

BACKGROUND

We conducted a population-based, nation-wide, prospective study to identify who introduced pertussis into the household of infants aged 6 months admitted to the hospital for pertussis in the Netherlands.

METHODS

During the period 2006-2008, a total of 560 household contacts of 164 hospitalized infants were tested by polymerase chain reaction, culture, and serological examination to establish Bordetella pertussis infection. Clinical symptoms and vaccination history were obtained by a questionnaire submitted during sample collection and 4-6 weeks afterwards.

RESULTS

Overall, 299 household contacts (53%) had laboratory-confired pertussis; 159 (53%) had symptoms compatible with typical pertussis infection, and 42 (14%) had no symptoms. Among children vaccinated with a whole-cell vaccine, 17 (46%) of 37 had typical pertussis 1-3 years after completion of the primary series, compared with 9 (29%) of 31 children who had been completely vaccinated with an acellular vaccine. For 96 households (60%), the most likely source of infection of the infant was established, being a sibling (41%), mother (38%), or father (17%).

CONCLUSIONS

If immunity to pertussis in parents is maintained or boosted, 35%-55% of infant cases could be prevented. Furthermore, we found that, 1-3 years after vaccination with whole-cell or acellular vaccine, a significant percentage of children are again susceptible for typical pertussis. In the long term, pertussis vaccines and vaccination strategies should be improved to provide longer protection and prevent transmission.

Kinetics of CD4+ T cell repopulation of lymphoid tissues after treatment of HIV-1 infection

Potent combinations of antiretroviral drugs diminish the turnover of CD4+ T lymphocytes productively infected with HIV-1 and reduce the large pool of virions deposited in lymphoid tissue (LT). To determine to what extent suppression of viral replication and reduction in viral antigens in LT might lead correspondingly to repopulation of the immune system, we characterized CD4+ T lymphocyte populations in LT in which we previously had quantitated viral load and turnover of infected cells before and after treatment. We directly measured by quantitative image analysis changes in total CD4+ T cell counts, the CD45RA+ subset, and fractions of proliferating or apoptotic CD4+ T cells. Compared with normal controls, we documented decreased numbers of CD4+ T cells and increased proliferation and apoptosis. After treatment, proliferation returned to normal levels, and total CD4+ T and CD45RA+ cells increased. We discuss the effects of HIV-1 on this subset based on the concept that renewal mechanisms in the adult are operating at full capacity before infection and cannot meet the additional demand imposed by the loss of productively infected cells. The slow increases in the CD45RA+ CD4+ T cells are consistent with the optimistic conclusions that (i) renewal mechanisms have not been damaged irreparably even at relatively advanced stages of infection and (ii) CD4+ T cell populations can be partially restored by control of active replication without eradication of HIV-1.

Decrease of HIV-1 RNA levels in lymphoid tissue and peripheral blood during treatment with ritonavir, lamivudine and zidovudine. Ritonavir/3TC/ZDV Study Group

OBJECTIVES

Triple combination treatment of HIV-1 infection using two reverse transcriptase inhibitors and a protease inhibitor can result in significant and sustained decreases in the quantity of viral RNA in peripheral blood. Lymphoid tissue, however, constitutes the major reservoir of HIV in infected patients. Study of the viral burden in these tissues has provided additional insight in the efficacy of antiretroviral treatment.

DESIGN

Patients were randomized into two groups in order to study differences in the development of resistance to reverse transcriptase inhibitors. Group I started treatment with all three drugs simultaneously. Group II started with ritonavir monotherapy, aiming at initial reduction in virus production before the addition of lamivudine and zidovudine 3 weeks later.

METHODS

Changes in the amount of HIV in plasma and tonsillar lymphoid tissue during 24 weeks of treatment with ritonavir, lamivudine and zidovudine were studied by reverse transcriptase polymerase chain reaction.

RESULTS

Thirty-three antiretroviral-naive HIV-infected patients were included for analysis. After 24 weeks, median CD4+ cell count increased by 152 x 10(6)/l and median plasma viral RNA levels decreased by at least 2.87 log10 copies/ml. In 88% of the patients remaining on treatment, plasma RNA levels were below the quantification limit of the assay used (mean, 2.4 log10 copies/ml). The lymphoid tissue viral burden, ranging from 9.16 to 8.52 log10 copies/g at baseline, was markedly reduced with at least 2.1 log10 copies/g by week 24 in the five patients analysed. Eight patients (24%) withdrew because of side-effects. In one patient in group II, ritonavir and lamivudine resistance-associated mutations developed.

CONCLUSIONS

Treatment with this triple antiretroviral drug combination produced a durable and strong decrease of HIV-1 RNA burden in both plasma and lymphoid tissue.

Spread and epidemiology of Clostridium difficile polymerase chain reaction ribotype 027/toxinotype III in The Netherlands

BACKGROUND

After reports of emerging outbreaks in Canada and the United States, Clostridium difficile-associated disease (CDAD) due to polymerase chain reaction ribotype 027 was detected in 2 medium-to-large hospitals in The Netherlands in 2005.

METHODS

National surveillance was initiated to investigate the spread and the epidemiology of CDAD. Microbiologists were asked to send strains recovered from patients with a severe course of CDAD or recovered when an increased incidence of CDAD was noted. A standardized questionnaire was used to collect demographic, clinical, and epidemiological patient data. Strains were characterized by polymerase chain reaction ribotyping, toxinotyping, the presence of toxin genes, and antimicrobial susceptibility.

RESULTS

During the period from February 2005 through November 2006, 1175 stool samples from 863 patients were sent from 50 health care facilities. Of these patients, 218 (25.3%) had CDAD due to ribotype 027, and 645 patients (74.7%) had CDAD due to other ribotypes, mainly 001 (17.8%) and 014 (7.2%). Polymerase chain reaction ribotype 027 was more frequently present in general hospitals than in academic hospitals (odds ratio [OR], 4.38; 95% confidence interval [CI], 1.60-12.0). Outbreaks of CDAD were observed in 10 hospitals and in 1 nursing home. Patients infected with ribotype 027 were significantly older (OR, 2.18; 95% CI, 1.43-3.33), and significantly more patients used fluoroquinolones (OR, 2.88; 95% CI, 1.01-8.20), compared with those who were infected with other ribotypes. Clear trends were observed for more severe diarrhea (OR, 1.99; 95% CI, 0.83-4.73), higher attributable mortality (6.3% vs. 1.2%; OR, 3.30; 95% CI, 0.41-26.4), and more recurrences (OR, 1.44; 95% CI, 0.94-2.20).

CONCLUSIONS

Ribotype 027 was found in 20 (18.3%) of 109 hospitals in The Netherlands, with a geographic concentration in the western and central parts of the country. The clinical syndrome in patients with CDAD differed on the basis of ribotype. Thus, early recognition of the ribotype has benefits.

Immunopathology as a result of highly active antiretroviral therapy in HIV-1-infected patients

OBJECTIVE

Unusual clinical inflammatory syndromes associated with underlying previously unrecognized opportunistic infections are increasingly being noted shortly after starting highly active antiretroviral therapy (HAART). This study examined the possible relationship between such unexpected disease manifestations and in vitro parameters of microbial antigen-specific immune reactivity in patients infected with HIV-1 who had a Mycobacterium avium intracellulare or Mycobacterium xenopi infection.

DESIGN

In vitro T-cell proliferation experiments were performed after specific stimulation of a patient's peripheral blood mononuclear cells (PBMC) with M. avium and M. xenopi antigen and non-specific stimulation with phytohaemagglutinin (PHA). The results were compared with appropriate controls.

PATIENTS

Five patients who presented with unusual clinical syndromes associated with M. avium or M. xenopi infection within weeks of experiencing large rises in CD4+ cell counts following the initiation of antiretroviral therapy.

RESULTS

In all patients except one, mycobacteria-specific lymphoproliferative responses rose significantly following HAART; this was temporally associated with elevations in CD4+ cell counts and the occurrence of clinical disease. The patient with M. xenopi infection appeared to clear his infection subsequently without antimycobacterial therapy. In three of the four patients with M. avium infection, antimycobacterial treatment could be stopped without recurrence of infection.

CONCLUSION

Our findings support the hypothesis that HAART may lead to clinically relevant inflammation as a result of restoration of specific immune reactivity against microbial pathogens that are subclinically present at the time treatment is initiated. Continuation of HAART may subsequently result in protective immunity and clearance of infection.

Clostridium difficile ribotype 027, toxinotype III, the Netherlands

Outbreaks due to Clostridium difficile polymerase chain reaction (PCR) ribotype 027, toxinotype III, were detected in 7 hospitals in the Netherlands from April 2005 to February 2006. One hospital experienced at the same time a second outbreak due to a toxin A–negative C. difficile PCR ribotype 017 toxinotype VIII strain. The outbreaks are difficult to control.

Update of Clostridium difficile-associated disease due to PCR ribotype 027 in Europe

Recent outbreaks of Clostridium difficile-associated diarrhoea (CDAD) with increased severity, high relapse rate and significant mortality have been related to the emergence of a new, hypervirulent C. difficile strain in North America, Japan and Europe. Definitions have been proposed by the European Centre of Disease Prevention and Control (ECDC) to identify severe cases of CDAD and to differentiate community-acquired cases from nosocomial CDAD (http://www.ecdc.europa.eu/documents/pdf/Cl_dif_v2.pdf). CDAD is mainly known as a healthcare-associated disease, but it is also increasingly recognised as a community-associated disease. The emerging strain is referred to as North American pulsed-field type 1 (NAP1) and PCR ribotype 027. Since 2005, individual countries have developed surveillance studies to monitor the spread of this strain. C. difficile type 027 has caused outbreaks in England and Wales, Ireland, the Netherlands, Belgium, Luxembourg, and France, and has also been detected in Austria, Scotland, Switzerland, Poland and Denmark. Preliminary data indicated that type 027 was already present in historical isolates collected in Sweden between 1997 and 2001.

Alternative multidrug regimen provides improved suppression of HIV-1 replication over triple therapy

OBJECTIVE

To compare the viral suppression of two antiretroviral regimens using three drugs or five drugs.

DESIGN

Two open-label studies using a three-drug (zidovudine, lamivudine and ritonavir) and a five-drug regimen (zidovudine, lamivudine, abacavir, indinavir and nevirapine) in study-drug-naive patients, except for one in the five-drug study.

METHODS

Participants with > or = 10 000 HIV-1 RNA copies/ml in plasma at baseline were compared by means of Kaplan-Meier curves for time to < 50 copies/ml, as well as linear regression analysis for the first phase of decline using log-transformed copy numbers.

RESULTS

The elimination rate constants for HIV-1 RNA in 15 participants of the three-drug study were compared with nine participants of the five-drug study. The level of < 50 copies/ml was reached earlier when using the five-drug than when using the three-drug regimen (P log rank = 0.0005): median time to reach this level was 4 weeks and 12 weeks, respectively. No differences were found in HIV-1 RNA elimination rate constants in the first 2 weeks after the initiation of therapy. When the viral load declines were calculated from day 2 onwards, adjusting for differences in pharmacological delay of the drugs used, again no differences in early viral load decline were found between the two regimens.

CONCLUSION

With the five drugs used in this study, the median time to reach < 50 HIV-1 RNA copies/ml was 8 weeks shorter than with the three-drug regimen. This finding shows that suppression of viral load in HIV-infection by standard triple-drug therapy can be improved upon.

Functional T cell reconstitution and human immunodeficiency virus-1-specific cell-mediated immunity during highly active antiretroviral therapy

Lymphoproliferative responses (LPRs) to recall antigens (Ags) and human immunodeficiency virus type 1 (HIV-1) Gag and frequencies of circulating HIV-1-specific cytotoxic T lymphocyte precursors (CTLps) were measured in 12 patients undergoing highly active antiretroviral therapy (HAART) after long-standing HIV-1 infection. LPRs to at least 1 recall Ag became detectable or increased in all patients during HAART. No significant LPRs to Gag-p24 were observed, whereas 4 of 8 patients tested presented with Gag-p17-specific LPRs. HIV-1-specific CTLp frequencies became measurable or increased early during therapy in 6 of 10 patients tested and were maintained or decreased thereafter. Increasing HIV-1-specific CTLp frequencies were seen only in association with partial HAART failure in 1 patient. In conclusion, restoration of CD4+ T lymphocyte responsiveness to recall Ags is achieved during HAART. The data provide evidence for limited HIV-1-specific CD4+ memory T cells during advanced HIV-1 infection and suggest that both CD4+ and CD8+ HIV-1-specific T cells are poorly stimulated when viral load is suppressed.

Immune reconstitution after 2 years of successful potent antiretroviral therapy in previously untreated human immunodeficiency virus type 1-infected adults

Today's antiretroviral combination regimens can induce significant and sustained decreases in human immunodeficiency virus (HIV)-RNA levels, allowing the immune system to recover. To what extent immune reconstitution is possible and what factors determine the outcome have thus far not been resolved. We studied 19 subjects, treated for 2 years with protease inhibitor-containing triple therapy, who had a strong suppression of HIV-RNA levels. CD4+ T-cell numbers increased from medians of 170 to 420x106 cells/L, but in a number of subjects T-cell numbers did not further increase after week 72, without having reached normal values. Long-term CD4+ T-cell change was mainly caused by a slow but continuous increase in naive CD4+ T cells (CD45RA+CD62L+) and was predicted by the baseline number of these cells. Our data indicate that long-term immunological recovery is gradual, even during strong suppression of viral replication, not always complete, and dependent on the preexisting level of naive CD4+ T cells.

Laboratory methods for case finding in human psittacosis outbreaks: a systematic review

Background

Psittacosis outbreak investigations require rapid identification of cases in order to trace possible sources and perform public health risk assessments. In recent outbreaks in the Netherlands, such investigations were hampered by the non-specificity of laboratory testing methods to identify human Chlamydia psittaci infections.

Method

A systematic search of PubMed and Scopus databases of literature published between 01 January, 1986 and 03 July, 2017 was done to find best practices of laboratory-testing methods used in psittacosis outbreaks of two or more human cases. Reference lists of included articles were hand searched to identify additional articles.

Results

Thirty-seven eligible articles were identified, describing 44 human psittacosis outbreaks in 12 countries. Laboratory tests performed were PCR (with various targets), serologic tests (complement binding reactions, ELISA’s, immunofluorescence tests and immuno-peroxidase tests) and culture, in various combinations. The literature provided no ‘gold standard’ laboratory testing strategy to identify recent human C. psittaci infections. In most psittacosis outbreaks, for a considerable number of cases (or tested individuals in an exposed cohort), C. psittaci infection could not be confirmed, nor excluded as causative pathogen. None of the testing strategies was found to be suitable for (nearly) full case finding.

Conclusion

PCR enables rapid identification of human psittacosis patients and helps source finding by genotyping but has the disadvantage that sensitivity is high only in the acute phase. In outbreak situations, there is often a time delay and therefore, there is a need for new serologic testing methods next to PCR, with good specificity and sensitivity. Moreover, serum is easier to collect than the preferred diagnostic materials for PCR. A serologic test that can reliably confirm infection status without the necessity of convalescent serum sampling would enhance case finding, source tracing, identification of risk factors and assessment of burden of disease in various settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3317-0) contains supplementary material, which is available to authorized users.

Potent antiretroviral therapy initiates normalization of hypergammaglobulinemia and a decline in HIV type 1-specific antibody responses

Next to a profound T cell immunodeficiency, HIV-1 infection induces activation and dysfunction of B cells, resulting in hypergammaglobulinemia. Whereas T cell immune reconstitution with potent antiretroviral therapy has been extensively documented, limited data are available on B cell immune reconstitution. We studied the effect of potent antiretroviral therapy on antibody titers to the viral proteins gp120 and p24 and on total IgG concentrations. Three retrospectively chosen groups were studied: a successfully treated group, untreated controls, and subjects with virological failure after several months of successful therapy. In the successfully treated group, the median total IgG concentrations normalized, whereas they remained elevated in the untreated group and rebounded after an initial decline in the therapy failure group. The HIV-1-specific antibody titers declined in the successfully treated group and followed the rebound of the HIV RNA levels in the therapy failure group. With potent antiretroviral therapy the hypergammaglobulinemia normalized whereas HIV-1-specific immune responses were weakened. The weakening of antiviral immunity with therapy may be relevant for current attempts to gain immunological control over the virus through structured treatment interruptions or therapeutic vaccinations.

Rate of HIV-1 decline following antiretroviral therapy is related to viral load at baseline and drug regimen

OBJECTIVES AND DESIGN

The dynamics uf viral decline following the initiation of antiretroviral treatment were studied in 29 HIV-1-infected patients participating in a two-arm trial comparing immediate (group A: ritonavir, zidovudine and lamivudine) and delayed (group B: ritonavir supplemented by zidovudine and lamivudine on day 21) triple therapy. Parameters underlying viral dynamics were estimated using mathematical models tailored to these treatment protocols.

RESULTS

The decline in plasma HIV-1 density between day 0 and 21 was steeper in group A (-2.27+/- 0.46 log10) than group B (-1.87+/-0.56 log10). In a subset of patients amenable to full mathematical analysis, a short-lived productively infected cell compartment (producing approximately 97% of total virions) decayed with a half-life of 1.0-2.5 days, whereas a long-lived infected cell compartment decayed with a half-life of 18.8-32.8 days. Estimates for the time for the elimination of virus from these two cell populations ranged from 474 to 802 days. The rate of loss of productively infected CD4+ T cells was positively correlated with baseline viral load in group A and in the combined dataset.

CONCLUSIONS

These results suggest that HIV-infected cell populations may have a faster turnover in patients with higher viral loads due to higher infection rate parameters, higher rates of virus production, or lower virus clearance rates.

Large differences between test strategies for the detection of anti-Borrelia antibodies are revealed by comparing eight ELISAs and five immunoblots

We investigated the influence of assay choice on the results in a two-tier testing algorithm for the detection of anti-Borrelia antibodies. Eighty-nine serum samples from clinically well-defined patients were tested in eight different enzyme-linked immunosorbent assay (ELISA) systems based on whole-cell antigens, whole-cell antigens supplemented with VlsE and assays using exclusively recombinant proteins. A subset of samples was tested in five immunoblots: one whole-cell blot, one whole-cell blot supplemented with VlsE and three recombinant blots. The number of IgM- and/or IgG-positive ELISA results in the group of patients suspected of Borrelia infection ranged from 34 to 59%. The percentage of positives in cross-reactivity controls ranged from 0 to 38%. Comparison of immunoblots yielded large differences in inter-test agreement and showed, at best, a moderate agreement between tests. Remarkably, some immunoblots gave positive results in samples that had been tested negative by all eight ELISAs. The percentage of positive blots following a positive ELISA result depended heavily on the choice of ELISA–immunoblot combination. We conclude that the assays used to detect anti-Borrelia antibodies have widely divergent sensitivity and specificity. The choice of ELISA–immunoblot combination severely influences the number of positive results, making the exchange of test results between laboratories with different methodologies hazardous.

Influence of follicular dendritic cells on decay of HIV during antiretroviral therapy

Drug treatment of HIV type 1 (HIV-1) infection leads to a rapid initial decay of plasma virus followed by a slower second phase of decay. To investigate the role of HIV-1 retained on follicular dendritic cells (FDCs) in this process, we have developed and analyzed a mathematical model for HIV-1 dynamics in lymphoid tissue (LT) that includes FDCs. Analysis of clinical data using this model indicates that decay of HIV-1 during therapy may be influenced by release of FDC-associated virus. The biphasic character of viral decay can be explained by reversible multivalent binding of HIV-1 to receptors on FDCs, indicating that the second phase of decay is not necessarily caused by long-lived or latently infected cells. Furthermore, viral clearance and death of short-lived productively infected cells may be faster than previously estimated. The model, with reasonable parameter values, is consistent with kinetic measurements of viral RNA in plasma, viral RNA on FDCs, productively infected cells in LT, and CD4(+) T cells in LT during therapy.

Reversibility of the pathological changes in the follicular dendritic cell network with treatment of HIV-1 infection

Over the course of HIV-1 infection, the lymphoid follicles where the humoral immune response is generated initially increase in size and number and then progressively involute. In advanced disease, the network of the processes of follicular dendritic cells (FDCs) that serve as antigen repositories and anatomical substrate for B and T cells and antigen to interact is destroyed, contributing to the breakdown of the immune system. Because destruction of FDCs is associated with deposition of HIV-1, and much of the virus can be cleared from the network with antiretroviral therapy, we investigated the reversibility of damage. We measured the immunohistochemically stainable FDC compartment by quantitative image analysis, and we documented changes in this compartment at different stages of disease. We show that treatment, initiated even at advanced stages of HIV-1 disease, can slowly reverse pathological changes in the FDC network.

Antibiotic resistance of Escherichia coli isolated from uncomplicated UTI in general practice patients over a 10-year period

Recommendations of first choice antibiotic therapy need to be based on actual antibiotic susceptibility data. We determined the antibiotic susceptibility of E. coli in uncomplicated UTI among women and compared the results with 2004 and 2009. In 30 sentinel general practitioner practices of Nivel Primary Care database, urine samples were collected from women with symptoms of uncomplicated UTI. Patient characteristics, E. coli susceptibility, and ESBL production were analyzed. Six hundred eighty-nine urine samples were collected; E. coli was the most isolated uropathogen (83%). Antibiotic susceptibility was stable over time except for ciprofloxacin (96% in 2004, 97% in 2009, and 94% in 2014; P < 0.05). The susceptibility to co-amoxiclav was 88%, 87%, and 92% in 2004, 2009, and 2014, respectively. The prevalence of ESBL-producing E. coli increased from 0.1% in 2004 to 2.2% in 2014 (P < 0.05). Regional differences in antibiotic susceptibility for co-trimoxazole were found being the highest in the west (88%) and the lowest in the north (72%, P = 0.021). Ciprofloxacin susceptibility was related to antibiotic use in the past 3 months (97% no use versus 90% use, P = 0.002) and age > 70 years (P = 0.005). In 2014, prescription of fosfomycin increased compared to 2009 (14.3% versus 5.6%) at the expense of co-amoxiclav, co-trimoxazole, and fluoroquinolones (P < 0.05). The susceptibility percentages to most antimicrobial agents tested were stable over 10 years’ period although the prevalence of E. coli and ESBLs significantly increased. Performance of a survey with regular intervals is warranted.