HIV DNA reservoir and elevated PD-1 expression of CD4 T-cell subsets particularly persist in the terminal ileum of HIV-positive patients despite cART.

OBJECTIVES: Despite its importance as an HIV anatomic sanctuary, little is known about the characteristics of the HIV reservoir in the terminal ileum (TI). In blood, the immune checkpoint inhibitor programmed-death-1 (PD-1) has been linked to the HIV reservoir and T-cell immune dysfunction. We thus evaluated PD-1 expression and cell-associated HIV DNA in memory CD4 T-cell subsets from TI, peripheral blood (PB) and rectum (RE) of untreated and treated HIV-positive patients to identify associations between PD-1 and HIV reservoir in other sites. METHODS: Using mononuclear cells from PB, TI and RE of untreated HIV-positive (N = 6), treated (n = 18) HIV-positive and uninfected individuals (n = 16), we identified and sorted distinct memory CD4 T-cell subsets by flow cytometry, quantified their cell-associated HIV DNA using quantitative PCR and assessed PD-1 expression levels using geometric mean fluorescence intensity. Combined HIV-1 RNA in situ hybridization and immunohistochemistry was performed on ileal biopsy sections. RESULTS: Combined antiretroviral therapy (cART)-treated patients with undetectable HIV RNA and significantly lower levels of HIV DNA in PB showed particularly high PD-1 expression in PB and TI, and high HIV DNA levels in TI, irrespective of clinical characteristics. By contrast, in treatment-naïve patients HIV DNA levels in memory CD4 T-cell subsets were high in PB and TI. CONCLUSION: Elevated PD-1 expression on memory CD4 T-cells in PB and TI despite treatment points to continuous immune dysfunction and underlines the importance of evaluating immunotherapy in reversing HIV latency and T-cell reconstitution. As HIV DNA particularly persists in TI despite cART, investigating samples from TI is crucial in understanding HIV immunopathogenesis.

Torque Teno Virus plasma level as novel biomarker of retained immunocompetence in HIV-infected patients.

PURPOSE: To predict the course of immune recovery (IR) in HIV-1-infected patients after initiation of combined antiretroviral therapy (cART) by determination of the plasma concentration of Torque Teno Virus (TTV). TTV has been identified as marker for risk assessment in immunosuppressed patients after transplantation procedures. Here, TTV was analyzed in HIV-1-infected therapy-naïve patients to evaluate its use as predictor of the course of IR for guidance of individualized treatment. METHODS: TTV DNA was quantified in plasma samples of 301 therapy-naïve HIV-1-infected patients and correlated to CD4+ cell count, HIV viral load, presence of the herpes viruses CMV, EBV and HHV-8, age and sex. Patients were classified according to their initial CD4+ cell count and to the extent of CD4+ T-cell increase within the first year of cART. RESULTS: TTV DNA was detectable in 96% of the patients' plasma samples with a median TTV plasma concentration of 5.37 log10 cop/ml. The baseline CD4+ cell count was negatively correlated with TTV plasma concentration (p = 0.003). In patients with a CD4+ cell recovery < 50 cells/µl, the median TTV plasma concentration was significantly higher compared to patients with a CD4+ cell recovery of > 200 CD4+ cells/µl (5.68 log10 cop/ml versus 4.99 log10 cop/ml; p = 0.011). TTV plasma concentration in combination with baseline CD4+ cell count were significantly correlated to CD4+ cell recovery (p = 0.004). For all other parameters considered, no significant correlation for CD4+ cell recovery was found. CONCLUSION: Within the cohort, the significantly elevated TTV plasma concentration in patients with diminished CD4+ cell recovery indicates a more profound immune defect. Baseline TTV plasma concentrations and CD4+ cell count are predictive for the course of immune recovery in HIV-1-infected patients with severe immunodeficiency.

Hodgkin lymphoma is as common as non-Hodgkin lymphoma in HIV-positive patients with sustained viral suppression and limited immune deficiency: a prospective cohort study.

OBJECTIVES: The incidence of HIV-related non-Hodgkin lymphoma (NHL) but not that of Hodgkin lymphoma (HL) has been declining. The aim of the study was to compare HIV-infected patients with NHL and HL with respect to antiretroviral therapy (ART) exposure at the time of lymphoma diagnosis. METHODS: HIV-infected patients with NHL and HL included in a prospective multicentre cohort study since January 2005 were compared with respect to ART exposure and viral load at the time of lymphoma diagnosis. RESULTS: As of 31 December 2012, data for 329 patients with NHL and 86 patients with HL from 31 participating centres were available. Patients with HL were more likely to be on ART (73.5% vs. 39.1%, respectively; P < 0.001) and more frequently had a viral load below the detection limit (57.3% vs. 27.9%, respectively; P < 0.001) than patients with NHL. The proportion of patients with HL was 8.0% in ART-naïve patients, 34.8% in patients with current HIV RNA < 50 HIV-1 RNA copies/mL, and 50.0% in patients with both HIV RNA < 50 copies/mL for > 12 months and a CD4 cell count of > 200 cells/µL. Of note, 45.8% of all patients with NHL were not currently on ART and had a CD4 count of < 350 cells/µL. CONCLUSIONS: This prospective cohort study shows that HL was as common as NHL in patients with sustained viral suppression and limited immune deficiency. In contrast to NHL, the majority of patients with HL were on effective ART, suggesting that ART provides insufficient protection from developing HL. The high proportion of untreated patients with NHL suggests missed opportunities for earlier initiation of ART.

[A 61-year-old man with jaundice following stomach cancer]. / 61-jähriger Patient mit Ikterus bei Zustand nach Magenkarzinom.

A 61-year-old man with occlusion of the common bile duct due to metachronous metastases after surgery for adenocarcinoma of the stomach underwent a bile drainage intervention using endoscopic ultrasound (EUS). A self-expanding metal stent was inserted into the common bile duct of the liver via the esophagus. Successful drainage of the bile fluid into the duodenum was achieved for 14 months until the death of the patient. EUS interventions are becoming increasingly common. Although many questions such as the methodological details still remain, EUS interventions have the potential to become standard procedures especially in the situation of malignant stenoses of the bile or pancreatic duct.

Therapy and prophylaxis of opportunistic infections in HIV-infected patients: a guideline by the German and Austrian AIDS societies (DAIG/ÖAG) (AWMF 055/066).

INTRODUCTION: There was a growing need for practical guidelines for the most common OIs in Germany and Austria under consideration of the local epidemiological conditions. MATERIALS AND METHODS: The German and Austrian AIDS societies developed these guidelines between March 2010 and November 2011. A structured Medline research was performed for 12 diseases, namely Immune reconstitution inflammatory syndrome, Pneumocystis jiroveci pneumonia, cerebral toxoplasmosis, cytomegalovirus manifestations, candidiasis, herpes simplex virus infections, varizella zoster virus infections, progressive multifocal leucencephalopathy, cryptosporidiosis, cryptococcosis, nontuberculosis mycobacteria infections and tuberculosis. Due to the lack of evidence by randomized controlled trials, part of the guidelines reflects expert opinions. The German version was accepted by the German and Austrian AIDS Societies and was previously published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF; German Association of the Scientific Medical Societies). CONCLUSION: The review presented here is a translation of a short version of the German-Austrian Guidelines of opportunistic infections in HIV patients. These guidelines are well-accepted in a clinical setting in both Germany and Austria. They lead to a similar treatment of a heterogeneous group of patients in these countries.

Terminally differentiated CD8 cells in HIV-infected children: HIV-GAG/POL specificity and IFN-γ production.

BACKGROUND: CD8 cells are key to antiviral immunity and can be divided by phenotype into early (CD28+ CD27+), intermediate (CD28-CD27+) and terminally differentiated subsets (CD28- CD27-). Despite effective HAART there is an unexplained expansion of CD8+CD28-CD27-T cells in HIV-infected children. The cytokine production and specificity of this terminally differentiated CD8 T cell subset in chronic virus infection is unclear. PATIENTS, METHODS & RESULTS: In a cohort of 26 HIV-infected children the cytokine production of terminally differentiated CD8 cells was analyzed by intracellular staining and FACS analysis and was compared to children with chronic hepatitis B infection and to healthy children. The specificity of CD8 subsets was analyzed by staining with Gag/Pol tetramers in a cohort of 13 patients. We show that an increased production of interferon-γ in terminally and early/intermediate differentiated CD8 cell subsets after stimulation is specific for HIV-infection. The expanded population of terminally differentiated CD8+CD28-CD27- T cells does include HIV Gag/Pol specific T cells in adults but not in children. CONCLUSION: The expansion of terminally differentiated CD8 cells might be important for immunomodulation but in children it does not appear to play a role in HIV Gag and Pol specific immunity.

[Endoscopic therapy for leaks in the gastrointestinal tract, the bile ducts and the pancreas]. / Endoskopische Therapie von Leckagen im Gastrointestinaltrakt, an den Gallenwegen und im Pankreas.

Surgery has been the mainstay of therapy in patients with gastrointestinal perforations, leakage or fistulas. New techniques for endoscopic closure of gastrointestinal perforations provide tools for an effective treatment by less invasive procedures. Temporary placement of covered self-expanding stents is an established therapy for oesophageal perforations and anastomotic leaks. Using conventional endoclips small perforations and leaks in the oesophagus and gastrointestinal tract may be closed. With the new over-the-scope-clips a more effective endoscopic full wall closure is possible in the upper gastrointestinal tract and the rectum. Endoscopically guided endoluminal vacuum therapy using polyurethane sponges is an established method for treating rectal leaks and is now increasingly used also in oesophageal leaks. Biliary leakage following endoscopic or surgical interventions is effectively treated with temporary bile stenting in most cases, but closure using metal stents or coiling may be necessary. Pancreatic leaks are a major therapeutic problem and may require multimodal therapies.

Maraviroc in treatment-experienced patients with HIV-1 infection - experience from routine clinical practice.

OBJECTIVE: Few data are available about the efficacy of maraviroc (MVC) during routine use. We characterized indications for MVC use and the efficacy of MVC in clinical practice. METHODS: Thirty-two patients treated with MVC at our institution between 2006 and 2009 were included. Genotypic (n +/- 31) and phenotypic (n +/- 13) tropism analysis was performed. We determined indications for MVC use, characteristics of antiretroviral combination partners and treatment outcome. RESULTS: Complete suppression of viral replication was achieved in 78% after 6 months. A median increase of 124 CD4+ cells/microl after 6 months was observed. Concordance between phenotypic and genotypic tropism was found in 75%. Indications for MVC treatment included treatment failure (n +/- 15), intolerance to previous antiretrovirals (n +/- 6) and add-on MVC for intensification without changing the current regimen (n +/- 11). The add-on strategy was used in patients with a relatively low viremia in order to achieve complete viral load suppression or in situations with suppressed viral load but judged as unstable due to an extensive resistance pattern. Salvage drugs most frequently combined with MVC were darunavir (n +/- 14) and raltegravir (n +/- 14). - The genotypic assay had predicted CXCR4 tropism in 5 patients, using a false positive rate (FPR) of 20%. Lowering the FPR to 5% predicted CCR5 tropism in 4 cases, still resulting in sustained complete viral response under MVC use. CONCLUSIONS: MVC containing salvage regimens achieve relevant CD4 cell increases and high viral response rates. In patients with few remaining treatment options it may be justified to lower the FPR-cutoff to 5% when predicting the coreceptor usage. Hereby, MVC could still be applied in selected patients with otherwise limited treatment options.

SEN Virus infection in HIV/HCV coinfected patients.

BACKGROUND: Chronic Hepatitis C Virus (HCV) infection is currently one of the most relevant coinfections in HIV positive patients. The influence of SEN Virus (SENV) on the outcome of HCV therapy in HIV/HCV coinfected patients who underwent combination therapy with pegylated interferon (PEG-IFN) and ribavirin is unclear. METHODS: SENV DNA was determined by polymerase chain reaction in 67 HIV/HCV coinfected patients, 77 HIV monoinfected patients, 95 treatment naive HCV monoinfetcted patients, and 122 healthy blood donors. Quantitative analysis was done for SENV H DNA. RESULTS: SENV DNA was detected in 8 of 67 (12%) HIV/HCV coinfected patients, in 9 of 77 (11.7%) HIV monoinfected patients, in 21 of 95 (22%) HCV monoinfected patients, and 12 of 122 (9.8%) healthy blood donors. HIV monoinfected patients showed the highest mean SENV H DNA level. The mean SENV H DNA was significantly lower in HIV/HCV coinfected patients compared to all other groups. The sustained virological response rates to combination therapy of HCV in HIV/HCV coinfected patients did not differ between patients with detectable SENV 5/8 (62.5%) and without SENV 28/59 (47.5%; p = 0.47). We found no significant difference in SENV H DNA pretreatment levels between nonresponders and responders to combination therapy (112 +/- 144 copies vs. 8 +/- 7 copies/ml; p = 0.27). CONCLUSION: Coinfection with HCV may reduce SENV H replication in HIV positive patients and results in significantly lower SENV H DNA levels in HIV/HCV coinfected patients. SENV infection has no influence on the outcome of HCV combination therapy in HIV/HCV coinfected patients.

Prevalence of oral lesions and periodontal diseases in HIV-infected patients on antiretroviral therapy.

A cross-sectional study examining oral manifestations was carried out in HIV-infected patients of a general HIV-specialized unit to provide prevalence data on oral lesions and periodontal diseases. The occurrence of oral lesions was correlated with demographic and clinical characteristics, immunologic and virologic parameters. Among 139 patients 86% presented any oral lesions with a prevalence of 76% of any periodontal diseases. Most periodontal lesions were classified as conventional gingivitis (28%) or periodontitis (30%). Dental plaque formation was associated with a higher prevalence of periodontal diseases (p = 0.01) and periodontal inflammation scores were higher in patients with more reduced CD4-counts (p = 0.03). Prevalence for HIV-specific oral lesions was 29% with a proportion of 9% of linear gingival erythema (LGE), 3.6% of necrotizing and ulcerative gingivitis (NUG) or periodontitis (NUP), 7% of oral candidiasis, 3.6% of oral hairy leucoplakia (OHL) and single other lesions. HIV-specific lesions (NUG/NUP, oral candidiasis and OHL) were found predominantly in patients with advanced immunosuppression and elevated viral load. Compared with data of oral diseases of the pre-HAART era prevalence of HIV-specific lesions was markedly reduced. Especially frequently known lesions such as oral candidiasis and OHL were less common seen. We noticed a shift of prevalence towards periodontal diseases. Lack of oral hygiene determined by plaque formation and reduced CD4-counts with pronounced periodontal inflammation can be seen as risk factors for periodontal disease. Overall high prevalence of manifestations underlines the importance of oral examination for the general practitioner and visits by oral specialists should become a routine procedure in HIV-patients care.

Efficacy and safety of twice daily first-line ritonavir/indinavir plus double nucleoside combination therapy in HIV-infected individuals. German Ritonavir/Indinavir Study Group.

OBJECTIVE: To evaluate the virological efficacy and safety of quadruple therapy with two nucleoside analogues and ritonavir (400 mg twice daily) plus indinavir (400 mg twice daily) combination in antiretroviral therapy-naive patients. DESIGN AND METHODS: An open-label, uncontrolled multicentre trial. Antiretroviral therapy-naive patients (n = 90) with high median baseline HIV RNA levels of 220,000 copies/ml (range, 36,000-2,943,000 copies/ml) and median CD4 cell count of 189 x 10(6)/l (range, 4-656 x 10(6)/l) were started on a twice daily regimen of either zidovudine/lamivudine (49%), stavudine/lamivudine (38%) or stavudine/didanosine (13%) plus ritonavir 400 mg twice daily and indinavir 400 mg twice daily combination therapy. CD4 cell counts and HIV RNA were determined at weeks 0, 4, 8, 12, 16, 20, and 24. Statistical analysis was performed on treatment as well as intent-to-treat, where missing values were accounted for as failure. RESULTS: In the intent-to-treat analysis at week 24, the proportion of patients with HIV RNA of < 500 copies/ml, and < 80 copies/ml was 86.7% and 71.1%, respectively. In the on-treatment analysis at week 24, 80.0% of patients had undetectable viral load in the ultrasensitive assay (< 80 copies/ml; n = 80). The quadruple therapy was well tolerated except for mild diarrhoea, initial nausea and increased triglyceride levels. Treatment was stopped in seven (7.7%) patients because of adverse events and three (3.3%) were lost to follow-up. CONCLUSIONS: Our preliminary data suggest that the protease inhibitor combination ritonavir/indinavir plus double nucleoside therapy appears to be effective and safe in short-term treatment (up to 24 weeks).

[HIV resistance. More the rule than an exception]. / HIV-Resistenz. Eher die Regel als die Ausnahme.

Resistance-associated mutations of the HIV genome are one major reason for failure of highly, active antiretroviral therapy. The accumulation of resistance is demonstrated by data from the HCUS-study, where resistant virus strains were isolated in about 50%. More than 60% of the patients showed therapy failure in this survey, and resistance was found in almost 80% of these. Mutations in the HIV genome were also described in treatment-naive patients. In the German Seroconverter Study the rate of resistance was 12%, in a multicenter study in Nordrhein-Westfalen resistant isolates were found in 14% of chronically infected cases. The wide distribution of HIV resistance in treated and untreated patients is an important problem in the management of HIV-infection. It requires a rational application of resistance testing. International studies are under way to further characterize the relevance of the phenomenon of HIV resistance.

[SARS--the facts. Transmission, diagnosis and managing suspected cases]. / SARS--die Fakten. Ubertragungswege, Diagnostik und Umgang mit Verdachtsfällen.

Severe Acute Respiratory Syndrome (SARS) is a new infectious disease that, in the short period between 1 February and 24 April 2003, has been diagnosed in more than 4000 patients. Its origin was traced to Guandong, a province in southeast China. The culprit organism was identified as a new coronavirus. The clinical presentation is unspecific and includes fever, respiratory symptoms, lymphopenia and pulmonary infiltrates on X-ray. Essential steps to prevent further dissemination of the virus are rapid identification, and treatment in an isolation unit. Despite all the international efforts and the rapid progress in the investigation of SARS coordinated by the World Health Organization (WHO), the epidemic has not yet been brought under control.

[Application of HIV drug resistance testing according to guidelines]. / Empfehlungen zum leitliniengerechten Einsatz der HIV-Resistenztestung.

Guidelines for application of HIV drug resistance testing have recently been develeped in Europe and the USA. This article discusses these recommendations. Since the widespread use of highly active antiretroviral therapy (HAART), quality of life has been improved for the majority of HIV-infected patients and the mortality rate has declined significantly. However, an incomplete suppression of viral replication results in selection of resistant viral strains resulting in a loss of HAART efficacy and worsening in the quality of life. Resistance testing is likely to improve virological monitoring of untreated but especially in pre-treated patients. Genotypical and phenotypical assays present similar results, but genotypical testing is the method of choice initially. Translation of resistance testing into clinical decisions-making requires consideration of a patient's history, interpretation of results by a validated algorithm, and expert advice. Problems of adherence should be avoided by counselling and therapeutic drug monitoring. Resistance testing or storage of a patient's plasma sample should be undertaken as early as possible in the disease history. If this is not possible, treatment with HAART, including a boosted protease inhibitor, is warranted. European and USA guidelines present similar recommendations. HIV drug resistance is preventable by rational choice of drug combinations in HAART. After development of resistance-associated mutations, drug resistance testing can preserve future treatment options and preventing further clinical deterioration. The method has been incorporated into national and international guidelines on the basis of good scientific evidence.

[Pre-exposure prophylaxis in HIV--a vision or soon a reality?]. / Präexpositionsprophylaxe bei HIV - Vision oder bald Realität?

Condom use is propagated as the most efficient measure to prevent HIV-transmission. For several reasons, condoms are NOT ALWAYS used or misapplied during sexual intercourse. Therefore, alternative preventive measures through intake of antiretroviral drugs before sexual intercourse with a (presumably) HIV-positive person are being considered, so called Pre-Exposure Prophylaxis (PrEP). In animal models the efficacy of HIV-PrEP was shown for Tenofovir alone or in combination with Emtricitabine). Several clinical studies are currently being conducted in different HIV-risk groups on various continents. First results from these studies are anticipated for the year 2010. In case of proven efficacy for HIV-PrEP, our health system would face a large interdisciplinary challenge. It would be a difficult task to define the appropriate recipients. Measures would have to be taken to limit possible misuse of antiretroviral drugs, due to the negative consequences with development of resistance, adverse events and illegal trading. It is already evident that HIV-PrEP will not provide absolute protection, nor will it replace other preventive strategies. However, if used cautiously, HIV-PrEP might be established as a useful supplement in the prevention of HIV. Paramount questions from the fields of epidemiology, behavioural science, logistics, health politics and ethics should be answered in advance.

Treatment of spondylodiscitis in human immunodeficiency virus-infected patients: a comparison of conservative and operative therapy.

STUDY DESIGN: Multicenter retrospective case series. OBJECTIVE: To determine relevant clinical presentation and outcome of human immunodeficiency virus (HIV)-positive patients with spondylodiscitis as a function of the treatment. SUMMARY OF BACKGROUND DATA: This is the first study comparing the clinical outcome of HIV-positive patients with spondylodiscitis as a function of the treatment. METHODS: We performed a national multicenter retrospective case series comparing operatively versus conservatively treated HIV-positive patients with spondylodiscitis presenting between 1991 and 2007. RESULTS: Twenty patients were included in the study. The average age of the patients at the time of admission was 43.0 years. The sex ratio m:w resulted in 2.3:1. On admission, 50% of the patients were in CDC stage C3. The CD4 T-cell count was determined as being 237.5/microL on average. At the occurrence of spondylodiscitis HIV had been known for a mean 8.5 years. In altogether 75% of the cases a pathogen was found. In 3 cases, mixed infections were present. Half of the patients received surgery. In none of these patients a wound infection or a delay of wound healing could be observed. One patient died during in-patient stay. Eleven of the 19 patients could be followed up a mean 13 months after discharge. In the follow-up period further 3 patients died on an average of 45 months after discharge. CONCLUSION: The occurrence of spondylodiscitis in HIV-positive patients is associated with a low CD4 T-cell count. The probability of mixed infections rises with a CD4 T-cell count <100/microL. The occurrence of spondylodiscitis in HIV-positive patients is accompanied by high mortality. Operative therapy of spondylodiscitis in HIV-positive patients is not associated with an increased surgical complication rate. HIV infection or AIDS should not have an influence on decision-making regarding conservative or operative therapy of spondylodiscitis.

Therapy outcome in patients with chronic hepatitis C: role of therapy supervision by expert hepatologists.

Previous large multicentre trials reported sustained virological response (SVR) rates of 45-80% in chronically infected hepatitis C virus (HCV) patients. However, it is unclear whether such a treatment success is also achieved in daily routine and to what extent it depends on expert hepatological supervision. This was retrospectively analysed in patients presenting at our outpatient department during May 1997 and March 2004 and receiving at least one treatment dose. A total of 302 treatment-naive HCV patients [72% genotypes 1 or 4 (n = 215), 25% genotypes 2/3 (n = 78) and 3% undetermined genotype (n = 9)] were included in the analysis. Out of these, 196 patients consulted an expert hepatologist at least once every 3 months during treatment [regular visitors (RV)], whereas in 106 patients treatment was performed and supervised by a general practitioner (irregular visitors). Both patient groups did not differ in their baseline characteristics. However, the virological response rates at the end of treatment (ETR; 146/196, 74%vs 51/106, 48%, P < 0.001) and 6 months thereafter (SVR; 129/196, 66%vs 36/106, 34%, P < 0.001) were significantly higher in RV. In patients treated with pegylated-interferon (PEG-IFN)/ribavirin, this difference was statistically highly significant (P < 0.001) for HCV genotypes 1 and 4 (treated patients: SVR: 62/101, 61%vs 14/51, 27%, P < 0.001), but not for genotypes 2/3. SVR rates were also significantly better in RV with advanced liver damage [SVR 69% (22/32) vs 25% (5/20), P = 0.004]. In regular and irregular visitors treatment was discontinued in 7% (14/196) and 15% (16/106) respectively (P = 0.015). Patients with unfavourable genotypes 1 and 4 or with advanced liver damage benefit from HCV therapy supervision by a specialist, probably because of less frequent treatment interruptions or dose reductions.

[Epidemiology of primary drug resistance in chronically HIV-infected patients in Nordrhein-Westfalen, Germany, 2001-2005]. / Epidemiologie der primären Medikamentenresistenz bei chronisch HIV-Infizierten in Nordrhein-Westfalen 2001-2005.

BACKGROUND AND OBJECTIVE: Primary HIV drug resistance, characterized by mutant virus strains in untreated HIV-infected persons, is of significant epidemiological significance. Primary resistance is associated with reduced efficacy of antiretroviral therapy (ART). We determined the prevalence of primary resistance in Nordrhein-Westfalen, Germany. PATIENTS AND METHODS: Genotypic resistance testing was performed in a prospective multicenter study in chronically infected previously untreated HIV-positive patients before administration of first-line ART. Mutations were classified according to the International AIDS Society USA guidelines and the geno2pheno interpretation tool. RESULTS: Between January 2001 and December 2005, resistance testing was performed in 831 patients. 77.4% were males, the mean age was 39 years (SD: 10.5). The mean duration of diagnosis of HIV infection was 1.6 years (SD: 3.4). 32.4% of patients were at CDC stage C, mean CD4 cell count was 236 /microl (SD: 205), and mean viral load was 206,855 copies/ml (SD: 450,610). In total, resistance-associated mutations were detected in 75 patients (9.0%; 95%CI, 7.1-11.0). After inclusion of mutations E44D and V118I, resistance was identified in 99 patients (11.9%; 95%CI, 9.7-14.1). 5.4% had mutations indicating nucleoside reverse transcriptase inhibitor (NRTI) resistance (95%CI, 3.9-7.0), 3.0% had non-NRTI resistance (95%CI, 1.8-4.2), and 2.4% had protease inhibitor resistance (95%CI, 1.4-3.4), respectively. Two-class resistance was detected in 0.8% (95%CI, 0.2-1.5), three-class resistance in 0.5% (95%CI, 0.01-1.0). Mutations indicating revertant variants of resistant strains were found in 3.9% (95%CI, 2.5-5.2). Considering the variables age, gender, time since diagnosis, CDC stage, CD4 cell count, viral load, HIV subtype, ethnic origin, and HIV transmission group, no significant risk factor for the presence of primary resistance was demonstrated in univariate and mutlivariate analyses. CONCLUSION: The prevalence of primary resistant virus strains was about 10% in chronically infected ART-naive HIV-patients in the largest federal state of Germany. The majority of these patients had NRTI-associated resistance. No risk factor for the presence of primary drug resistance was identified. Because of the high prevalence and the possible impact on efficacy of drug treatment, routine genotypic resistance testing should be performed in untreated HIV-positive patients before administration of first-line ART.