Next-Generation Sequencing in a Direct Model of HIV Infection Reveals Important Parallels to and Differences from In Vivo Reservoir Dynamics.

Next-generation sequencing (NGS) represents a powerful tool to unravel the genetic make-up of the HIV reservoir, but limited data exist on its use in vitro Moreover, most NGS studies do not separate integrated from unintegrated DNA, even though selection pressures on these two forms should be distinct. We reasoned we could use NGS to compare the infection of resting and activated CD4 T cells in vitro to address how the metabolic state affects reservoir formation and dynamics. To address these questions, we obtained HIV sequences 2, 4, and 8 days after NL4-3 infection of metabolically activated and quiescent CD4 T cells (cultured with 2 ng/ml interleukin-7). We compared the composition of integrated and total HIV DNA by isolating integrated HIV DNA using pulsed-field electrophoresis before performing sequencing. After a single-round infection, the majority of integrated HIV DNA was intact in both resting and activated T cells. The decay of integrated intact proviruses was rapid and similar in both quiescent and activated T cells. Defective forms accumulated relative to intact ones analogously to what is observed in vivo Massively deleted viral sequences formed more frequently in resting cells, likely due to lower deoxynucleoside triphosphate (dNTP) levels and the presence of multiple restriction factors. To our surprise, the majority of these deleted sequences did not integrate into the human genome. The use of NGS to study reservoir dynamics in vitro provides a model that recapitulates important aspects of reservoir dynamics. Moreover, separating integrated from unintegrated HIV DNA is important in some clinical settings to properly study selection pressures.IMPORTANCE The major implication of our work is that the decay of intact proviruses in vitro is extremely rapid, perhaps as a result of enhanced expression. Gaining a better understanding of why intact proviruses decay faster in vitro might help the field identify strategies to purge the reservoir in vivo When used wisely, in vitro models are a powerful tool to study the selective pressures shaping the viral landscape. Our finding that massively deleted sequences rarely succeed in integrating has several ramifications. It demonstrates that the total HIV DNA can differ substantially in character from the integrated HIV DNA under certain circumstances. The presence of unintegrated HIV DNA has the potential to obscure selection pressures and confound the interpretation of clinical studies, especially in the case of trials involving treatment interruptions.

HIV-associated psoriasis: Epidemiology, pathogenesis, and management.

People living with HIV (PLWH) are affected by a higher incidence skin disorders, which are often associated with high morbidity and mortality. In particular, psoriasis affects PLWH severely and for a longer time than the general population. Human immunodeficiency virus (HIV) infection is characterized by a progressive decrease in CD4+ T-cell count, and it could seem paradoxical that psoriasis exacerbations are more frequent in this subset of patients than the general population, even though it is commonly observed at any stage of infection. For a long time, there have been limited therapeutic choices for PLWH affected by psoriasis. The introduction of the combined antiretroviral therapy dramatically changed the natural course of both HIV and psoriasis in PLWH, leading to an improvement of quality and duration of life. However, the clinical severity of psoriasis in PLWH often requires the use of immunosuppressant drugs. Knowledge about their safety and efficacy are limited to case-reports, small case-series and studies, therefore their use has not yet entered the routine. Further studies are needed to determine if immunosuppressive drugs can be safely and effectively used in PLWH affected by psoriasis and other autoimmune disorders.

Measuring integrated HIV DNA ex vivo and in vitro provides insights about how reservoirs are formed and maintained.

The identification of the most appropriate marker to measure reservoir size has been a great challenge for the HIV field. Quantitative viral outgrowth assay (QVOA), the reference standard to quantify the amount of replication-competent virus, has several limitations, as it is laborious, expensive, and unable to robustly reactivate every single integrated provirus. PCR-based assays have been developed as an easier, cheaper and less error-prone alternative to QVOA, but also have limitations. Historically, measuring integrated HIV DNA has provided insights about how reservoirs are formed and maintained. In the 1990s, measuring integrated HIV DNA was instrumental in understanding that a subset of resting CD4 T cells containing integrated HIV DNA were the major source of replication-competent virus. Follow-up studies have further characterized the phenotype of these cells containing integrated HIV DNA, as well as shown the correlation between the integration levels and clinical parameters, such as duration of infection, CD4 count and viral load. Integrated HIV DNA correlates with total HIV measures and with QVOA. The integration assay has several limitations. First, it largely overestimates the reservoir size, as both defective and replication-competent proviruses are detected. Since defective proviruses are the majority in patients on ART, it follows that the number of proviruses capable of reactivating and releasing new virions is significantly smaller than the number of integrated proviruses. Second, in patients on ART clonal expansion could theoretically lead to the preferential amplification of proviruses close to an Alu sequence though longitudinal studies have not captured this effect. Proviral sequencing combined with integration measures is probably the best estimate of reservoir size, but it is expensive, time-consuming and requires considerable bioinformatics expertise. All these reasons limit its use on a large scale. Herein, we review the utility of measuring HIV integration and suggest combining it with sequencing and total HIV measurements can provide insights that underlie reservoir maintenance.

Monitoring Integration over Time Supports a Role for Cytotoxic T Lymphocytes and Ongoing Replication as Determinants of Reservoir Size.

The dynamics of HIV reservoir accumulation off antiretroviral therapy (ART) is underexplored. Levels of integrated HIV DNA in peripheral blood mononuclear cells (PBMCs) were longitudinally monitored before and after antiviral therapy. HIV integration increased over time in both elite controllers (ECs; n = 8) and noncontrollers (NCs; n = 6) before ART, whereas integration remained stable in patients on ART (n = 4). The median annual fold change was higher in NCs than in ECs and negatively correlated with CD4/CD8 T-cell ratio. Cytotoxic T lymphocyte (CTL) function as assessed by infected CD4 T-cell elimination (ICE) and granzyme B activity did not significantly change over time in ECs, suggesting that the gradual increase in integrated HIV DNA observed in ECs was not a result of progressive loss of immune-mediated control. Also, acutely infected (n = 7) but not chronically infected (n = 6) patients exhibited a significant drop in integrated HIV DNA 12 months after ART initiation. In conclusion, in the absence of ART, integrated HIV accumulates over time both in NCs and in ECs, at variable individual rates. Starting ART early in infection leads to a greater drop in integrated HIV DNA than does initiating treatment after years of infection. The increase in integrated HIV DNA over time suggests that early treatment may be of benefit in limiting HIV reservoirs. IMPORTANCE: The establishment of a latent reservoir represents a barrier to cure among HIV-infected individuals. The dynamics of HIV reservoir accumulation over time in patients before antiviral therapy is underexplored, in large part because it is difficult to accurately and reproducibly measure the size of HIV reservoir in this setting. In our study, we compared the dynamics of integrated HIV DNA over time in ECs and NCs before and after ART was initiated. We found that integrated HIV DNA levels progressively increase over time in the absence of ART, but with a higher, albeit variable, rate in NCs compared to ECs. In addition, integrated HIV DNA declines more dramatically when ART is initiated in acute rather than chronic HIV infection, suggesting important differences between acute and chronic infection. Our study highlights the role of HIV replication and CTL control in reservoir accumulation in sanctuary sites and why ART appears to be more effective in acute infection.

Heel quantitative ultrasound in HIV-infected patients: a cross-sectional study.

PURPOSE: HIV infection has been associated with increased risk of osteoporosis and fragility fractures. Dual-energy X-ray absorptiometry (DXA) is the reference standard to assess bone mineral density (BMD); however, it is not easily accessible in several settings. Heel Quantitative ultrasound (QUS) is a radiation-free, easy-to-perform technique, which may help reducing the need for DXA. METHODS: In this cross-sectional study, we used heel QUS (Hologic Sahara(®)) to assess bone status in a cohort of HIV-infected patients. A QUS stiffness index (QUI) threshold >83 was used to identify patients with a low likelihood of osteoporosis. Moreover, we compared QUS results with those of 36 sex- and age-matched HIV-negative controls. RESULTS: 244 HIV-positive patients were enrolled. Median heel QUI value was 83 (73-96) vs. 93 (IQR 84-104) in the control group (p = 0.04). 110 patients (45 %) had a QUI value ≤83. Risk factors for low QUI values were age (OR 1.04 per year, 95 % CI 1.01-1.07, p = 0.004), current use of protease inhibitors (OR 1.85, CI 1.03-3.35, p = 0.039), current use of tenofovir (OR 2.28, CI 1.22-4.27, p = 0.009) and the number of risk factors for secondary osteoporosis (OR 1.46, CI 1.09-1.95, p = 0.01). Of note, QUI values were significantly correlated with FRAX score (r = -0.22, p = 0.004). According to EACS guidelines, 45 % of patients had risk factors for osteoporosis which make them eligible for DXA. By using QUS, we may avoid DXA in around half of them. CONCLUSIONS: As HIV-positive patients are living longer, the prevalence of osteoporosis is expected to increase over time. Appropriate screening, prevention and treatment are crucial to preserve bone health in this population. The use of screening techniques, such as heel QUS, may help reducing the need for DXA. Further studies are needed to define the diagnostic accuracy of this promising technique in the setting of HIV.

Duration of antimicrobial therapy in community acquired pneumonia: less is more.

Community acquired pneumonia (CAP) represents the most common cause of infection-related morbidity and mortality worldwide. Appropriate treatment of CAP is challenging and sometimes limited by the availability to obtain rapid and timely identification of the etiologic agent in order to initiate or deescalate the correct antimicrobial therapy. As a consequence, prescribers frequently select empiric antimicrobial therapy using clinical judgment, local patterns of antimicrobial resistance, and, sometimes, individual patient expectations. These issues may contribute to prolonged courses of inappropriate therapy. In this review, we discuss the evidence and recommendations from international guidelines for the management of CAP and the clinical trials that specifically addressed duration of antimicrobial therapy for CAP in adults. In randomized controlled trials comparing the clinical efficacy of a short-course antimicrobial regimen versus an extended-course regimen, no differences in terms of clinical success, bacterial eradication, adverse events, and mortality were observed. The use of biomarkers, such as procalcitonin, to guide the initiation and duration of antimicrobial therapy may reduce total antibiotic exposure and treatment duration, healthcare costs, and the risk of developing antimicrobial resistance. In clinical practice, antimicrobial stewardship interventions may improve the management of CAP and may help in reducing treatment duration. Sometimes "less is more" in CAP.

Pharmacological approaches to promote cell death of latent HIV reservoirs.

PURPOSE OF REVIEW: HIV requires lifelong antiviral treatment due to the persistence of a reservoir of latently infected cells. Multiple strategies have been pursued to promote the death of infected cells. RECENT FINDINGS: Several groups have focused on multipronged approaches to induce apoptosis of infected cells. One approach is to combine latency reversal agents with proapoptotic compounds and cytotoxic T cells to first reactivate and then clear infected cells. Other strategies include using natural killer cells or chimeric antigen receptor cells to decrease the size of the reservoir.A novel strategy is to promote cell death by pyroptosis. This mechanism relies on the activation of the caspase recruitment domain-containing protein 8 (CARD8) inflammasome by the HIV protease and can be potentiated by nonnucleoside reverse transcriptase inhibitors. SUMMARY: The achievement of a clinically significant reduction in the size of the reservoir will likely require a combination strategy since none of the approaches pursued so far has been successful on its own in clinical trials. This discrepancy between promising in vitro findings and modest in vivo results highlights the hurdles of identifying a universally effective strategy given the wide heterogeneity of the HIV reservoirs in terms of tissue location, capability to undergo latency reversal and susceptibility to cell death.

HIV RNA suppression and immune restoration: can we do better?

HAART has significantly changed the natural history of HIV infection: patients receiving antiretrovirals are usually able to control viremia, even though not all virological responders adequately recover their CD4+ count. The reasons for poor immune restoration are only partially known and they include genetic, demographic and immunologic factors. A crucial element affecting immune recovery is immune activation, related to residual viremia; indeed, a suboptimal virological control (i.e., low levels of plasma HIV RNA) has been related with higher levels of chronic inflammation and all-cause mortality. The sources of residual viremia are not yet completely known, even though the most important one is represented by latently infected cells. Several methods, including 2-LTR HIV DNA and unspliced HIV RNA measurement, have been developed to estimate residual viremia and predict the outcome of antiretroviral therapy. Considering that poor immunologic responders are exposed to a higher risk of both AIDS-related and non-AIDS-related diseases, there is a need of new therapeutic strategies, including immunomodulators and drugs targeting the latent viral reservoirs, in order to face residual viremia but also to "drive" the host immunologic responses.

Persistence of an intact HIV reservoir in phenotypically naive T cells.

Despite the efficacy of antiretroviral therapy (ART), HIV persists in a latent form and remains a hurdle to eradication. CD4+ T lymphocytes harbor the majority of the HIV reservoir, but the role of individual subsets remains unclear. CD4+ T cells were sorted into central, transitional, effector memory, and naive T cells. We measured HIV DNA and performed proviral sequencing of more than 1900 proviruses in 2 subjects at 2 and 9 years after ART initiation to estimate the contribution of each subset to the reservoir. Although our study was limited to 2 subjects, we obtained comparable findings with publicly available sequences. While the HIV integration levels were lower in naive compared with memory T cells, naive cells were a major contributor to the intact proviral reservoir. Notably, proviral sequences isolated from naive cells appeared to be unique, while those retrieved from effector memory cells were mainly clonal. The number of clones increased as cells differentiated from a naive to an effector memory phenotype, suggesting naive cells repopulate the effector memory reservoir as previously shown for central memory cells. Naive T cells contribute substantially to the intact HIV reservoir and represent a significant hurdle for HIV eradication.

Investigational drugs in HIV: Pros and cons of entry and fusion inhibitors (Review).

Despite the profound changes and improvements reached in the field of HIV treatment, tolerability and adherence to highly active antiretroviral therapy remains a challenge. Furthermore, multi-experienced patients could take advantage of drugs with different mechanisms of action to combat the spread of resistance to actual therapy. For these reasons identification of new HIV drugs is crucial. Among all the molecules that at present are under investigation, entry and fusion inhibitors pose an interesting class owing to their peculiar characteristics, including prevention of entry of the virus into the human cells. In this study, we reviewed articles, clinical trials, and conference communications about all the drugs under investigation belonging to the class of entry and fusion inhibitors that are at least in phase I clinical trials.

Circulating angiopoietin-like protein 2 levels are associated with decreased renal function in HIV+ subjects on cART: A potential marker of kidney disease.

Chronic kidney disease (CKD) is an important cause of morbidity and mortality in HIV-infected individuals, even in the antiretroviral therapy (ART) era. Inflammatory cytokines and adipokines have been suggested to play a role in the development of CKD. The aim of the present study was to examine the circulating levels of a novel proinflammatory cytokine, angiopoietin-like protein 2 (ANGPTL2), in a cohort of 72 HIV-positive subjects on ART. HIV-positive patients were on cART for at least one year. Urine and blood samples were collected. Various factors were analyzed including body mass index (BMI), smoking, and presence/treatment for comorbidities such as diabetes. The estimated glomerular filtration rate was calculated by using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Plasma samples obtained were stored and used to measure sCD14 and ANGPTL2 levels. Data were presented as mean (± standard deviation) or median (interquartile range) for continuous variables. Categorical variables were expressed as number (%). Variables were compared using Student's t-test, Mann-Whitney test, or χ2 test. The results showed an independent negative association between plasma ANGPTL2 and CKD-EPI values. Further prospective studies on larger cohorts are needed to evaluate the pathogenetic role of ANGPTL2 as well as its use as a diagnostic marker of renal dysfunction.

Longitudinal HIV sequencing reveals reservoir expression leading to decay which is obscured by clonal expansion.

After initiating antiretroviral therapy (ART), a rapid decline in HIV viral load is followed by a long period of undetectable viremia. Viral outgrowth assay suggests the reservoir continues to decline slowly. Here, we use full-length sequencing to longitudinally study the proviral landscape of four subjects on ART to investigate the selective pressures influencing the dynamics of the treatment-resistant HIV reservoir. We find intact and defective proviruses that contain genetic elements favoring efficient protein expression decrease over time. Moreover, proviruses that lack these genetic elements, yet contain strong donor splice sequences, increase relatively to other defective proviruses, especially among clones. Our work suggests that HIV expression occurs to a significant extent during ART and results in HIV clearance, but this is obscured by the expansion of proviral clones. Paradoxically, clonal expansion may also be enhanced by HIV expression that leads to splicing between HIV donor splice sites and downstream human exons.

Head and neck squamous cell carcinoma and its correlation with human papillomavirus in people living with HIV: a systematic review.

Over the last 20 years we assisted to an increase in the mean age of People Living with HIV and their comorbidities. Especially, there was an increase in Human Papillomavirus-related head and neck squamous cell carcinomas. Despite their increasing incidence in HIV-positive people, mechanisms that lead to their development and progression are only partially understood. The aim of this review is to identify key data and factors about HPV-related head and neck squamous cell carcinoma in HIV-seropositive patients. Systematic search and review of the relevant literature-peer-reviewed and grey-was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. We included in our review only the 35 full-text articles we considered the most substantial. It is mandatory to improve our knowledge about the interactions existing between HPV and HIV, and about their actions on oral mucosa immune system.

Baseline CD4/CD8 T-Cell Ratio Predicts Prompt Immune Restoration Upon cART Initiation.

INTRODUCTION: The reversal of CD4/CD8 ratio is considered an independent predictor of death in the general population, where the ratio physiologically decreases with aging. Despite effective cART, CD4/CD8 normalization does not always occur in HIV-positive subjects. In the setting of HIV, low CD4/CD8 T-cell ratio correlates with immune activation and non-AIDS events. The aim of the study was to evaluate the rate and predictors of CD4/CD8 ratio normalization in a cohort of HIV-positive subjects starting combination antiretroviral therapy (cART). METHODS: This is a retrospective-prospective observational cohort study conducted at the Unit of Infectious Diseases of the University of Catania. Our cohort included naive individuals who initiated cART from January 2007 to December 2013. RESULTS: A total of 123 individuals were enrolled. The median age was 38 years (IQR 29-44). The median baseline CD4+ T-cell count was 288 cells/µl (IQR 105-400). 83 (67.5%) had a CD4+ T-cell count <350/µl; baseline median CD4/CD8 ratio was 0.24 (IQR 0.13-0.4); 65 patients (52.8%) had a HIV viral load >100,000 copies/ml. At 24 months, 33 individuals (26.8%) normalized their CD4/CD8 ratio, with a median time to CD4/CD8 ratio normalization of 17 months (IQR 12-30). In univariate analysis, a baseline CD4+ T-cell count >350/µl (p <0.01), a baseline CD4/CD8 ratio >0.5 (p <0.01), CDC stage A (p<0.01) and an efavirenz-based first-line regimen (p<0.05) were associated with CD4/CD8 ratio normalization. In multivariate logistic analysis, the only predictor of CD4/CD8 normalization was a baseline ratio >0.5 (OR 4.3 (1.7-11.2), p=0.003). CONCLUSION: Starting cART with a ratio >0.5 is associated with an increased likelihood to normalize CD4/CD8 ratio. Early diagnosis should be encouraged in order to treat patients promptly and favor a more robust immunological reconstitution.

Diagnostic and therapeutic management of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is an increasing health problem, representing the second cause of cancer-related mortality worldwide. The major risk factor for HCC is cirrhosis. In developing countries, viral hepatitis represent the major risk factor, whereas in developed countries, the epidemic of obesity, diabetes and nonalcoholic steatohepatitis contribute to the observed increase in HCC incidence. Cirrhotic patients are recommended to undergo HCC surveillance by abdominal ultrasounds at 6-mo intervals. The current diagnostic algorithms for HCC rely on typical radiological hallmarks in dynamic contrast-enhanced imaging, while the use of α-fetoprotein as an independent tool for HCC surveillance is not recommended by current guidelines due to its low sensitivity and specificity. Early diagnosis is crucial for curative treatments. Surgical resection, radiofrequency ablation and liver transplantation are considered the cornerstones of curative therapy, while for patients with more advanced HCC recommended options include sorafenib and trans-arterial chemo-embolization. A multidisciplinary team, consisting of hepatologists, surgeons, radiologists, oncologists and pathologists, is fundamental for a correct management. In this paper, we review the diagnostic and therapeutic management of HCC, with a focus on the most recent evidences and recommendations from guidelines.

Epstein-barr virus- and Kaposi sarcoma-associated herpesvirus-related malignancies in the setting of human immunodeficiency virus infection.

The human gammaherpesvirus family includes Epstein-Barr virus (EBV) and human herpesvirus (HHV)-8, also known as Kaposi sarcoma-associated herpesvirus (KSHV). In human immunodeficiency virus (HIV)-infected patients, both EBV and KSHV have been implicated in the development of a wide range of tumors. KSHV-associated diseases include Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). EBV has been associated with the development of several malignancies, including Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). The introduction of highly active antiretroviral therapy (HAART) has dramatically modified the natural history of HIV infection, causing a decline in the incidence of acquired immunodeficiency syndrome (AIDS)-defining malignancies, including KS. However, it has had a less favorable impact on EBV-related malignancies and NHLs remain the most common tumors in the HAART era. In this review, we briefly summarize the pathogenesis, epidemiology, clinical features, and therapeutic approach to EBV- and KSHV-associated tumors in the setting of HIV infection.

Neurocysticercosis in a 23-year-old Chinese man.

PATIENT: Male, 23 FINAL DIAGNOSIS: Neurocysticerosis Symptoms: Diplopia • fever • headache • insomnia • neck stiffness • vomiting MEDICATION: Albendazole Clinical Procedure: - Specialty: Neurology. OBJECTIVE: Challenging differential diagnosis. BACKGROUND: Neurocysticercosis is a brain infection caused by the larval stage of the tapeworm Taenia (T.) solium. It is the most important parasitic disease of the human central nervous system and represents the most common cause of acquired epilepsy in developing countries. CASE REPORT: Here, we report the case of a 23-year-old Chinese man who presented to the emergency department with a 7-day history of helmet headache radiating to the nuchal region and associated with vomiting, confusion, and fever. Cerebrospinal fluid (CSF) was clear, with increased pressure, lymphocytic pleocytosis, decreased glucose, and increased protein levels. Bacterial antigen detection test on CSF was negative, as were CSF bacterial and fungal cultures. Despite broad-spectrum antibiotic and antiviral therapy, the patient still complained of insomnia, diplopia, headache, neck stiffness, and pain in the sacral region. A second LP was performed and CSF had the same characteristics as the first LP. A brain and spinal cord MRI revealed widespread arachnoiditis and small septated cysts with CSF-like signal in the cisterna magna, within the fourth ventricle, and at the level of L3-L4. Cysticercus-specific immunoglobin G antibodies were detected by ELISA in the CSF. The patient received albendazole (15 mg/kg/day) and dexamethasone (5 mg/day) for 4 weeks, with progressive resolution of neurological symptoms. CONCLUSIONS: This case shows that, even if rare, neurocysticercosis may be responsible for meningeal symptoms and should be included in the differential diagnosis, especially in patients from endemic countries.

High prevalence of parotideal abnormalities among HCV infected patients.

Several salivary diseases, such as Sjogren syndrome (SS), chronic lymphocytic sialadenitis and parotid non-Hodgkin's lymphoma, may occur in the setting of HCV infection. Our aim was to evaluate the prevalence of parotid abnormalities in a cohort of 310 patients with chronic hepatitis C (CHC) attending the Unit of Infectious Diseases of the Garibaldi Nesima Hospital of Catania. Our control group consisted of 188 patients with chronic HBV infection. We found that the prevalence of parotideal diseases was significantly higher among HCV-infected patients in comparison with HBV-infected (17% vs. 1%). Indeed, 53 CHC subjects had parotideal abnormalities: 24 patients (45.3%) had lymphoepithelial cysts of the salivary gland, six patients (11.3%) had a benign tumour, six patients (11.3%) had granulomatous lesions, 12 patients (22.7%) had Sjogren's syndrome and four patients (7.5%) were diagnosed as having chronic lymphocytic sialadenitis. Finally, one patient (1.9%) had parotid non-Hodgkin's lymphoma. In conclusion, parotideal abnormalities are common among HCV-infected individuals and targeted diagnostic protocols may help identify parotid involvement in this population of subjects.

Optimal duration of antimicrobial therapy in ventilator-associated pneumonia: What is the role for procalcitonin?

Hospital-acquired pneumonia (HAP) is the major cause of hospital-acquired infections in critically ill patients. Up to 90% of intensive care unit episodes of HAP occur in mechanically ventilated patients, who may develop what is termed ventilator-associated pneumonia (VAP). An appropriate duration of antimicrobial therapy is crucial in the management of HAP: on the one hand, delay in administration of proper therapy has been associated with an increased risk of treatment failure and mortality; on the other hand, unnecessary prolongation of antimicrobial treatment may favour the emergence of multidrug-resistant bacteria and increase healthcare costs. In this review, we discuss the evidence and recommendations from international guidelines for the management of VAP and focus on randomised controlled trials comparing the clinical efficacy of a short-course vs. an extended-course antimicrobial regimen for the treatment of VAP in adults. In these trials, short-course regimens were as effective and safe as long-course regimens for the treatment of VAP, provided that infection was not due to difficult-to-treat micro-organisms such as non-fermenting Gram-negative bacilli. In addition, strategies incorporating individualised stop-points for antibiotics, i.e. clinical features or biomarkers such as procalcitonin, were shown to reduce antibiotic exposure, healthcare costs and the risk of developing antimicrobial resistance, without negatively affecting other outcomes.