Genotypic Resistance Testing Research Articles

Relative frequency of cytomegalovirus UL56 gene mutations detected in genotypic letermovir resistance testing

Genotypic testing for letermovir (LMV) resistance was performed by Sanger sequencing of cytomegalovirus terminase gene UL56 (codons 202–412) in 1165 diagnostic specimens, disclosing 36 sequence variants among 173 (14.8%) of the specimens, including one or more LMV resistance mutations in 134 specimens. Codon 325 mutations (C325Y/F/W/R) were the most common (108 specimens), followed by those at codon 369 (R369 S/G/T/K, 13 specimens) and V236M (11 specimens). Mutations V231L, N232Y, Q234R, L257F and V363I were detected in 1–3 specimens each. Combinations of codon 325 mutation and those at codons 236 or 369 were found in 6 specimens. Eleven novel sequence variants were phenotyped, validating Q234R, V363I and R369K as conferring 2- to 5-fold increased LMV 50% inhibitory concentrations (EC50). These findings indicate that UL56 codon 325 mutations conferring >3000-fold LMV EC50 are detected much more frequently in clinical practice than those conferring lower grade resistance, and suggest that a single step mutation to absolute LMV resistance is an ongoing concern in its therapeutic use.

Antiretroviral Drug Resistance in HIV Sequences From People Who Inject Drugs and Men Who Have Sex With Men Across 21 Cities in India.

BackgroundDrug resistance testing is limited in public-sector human immunodeficiency virus (HIV) care in India, and there are few systematic samplings for prevalent drug resistance mutations (DRMs), particularly among men who have sex with men (MSM) and people who inject drugs (PWID).MethodsWe conducted genotypic resistance testing on 915 HIV sequences sampled from viremic self-reported antiretroviral therapy (ART) experienced and naive PWID and MSM recruited from 21 cities across India in 2016–2017. We analyzed factors associated with resistance using logistic regression and evaluated evidence for transmitted resistance using phylogenetic analyses.ResultsOf the 915 participants sequenced, median age was 31, 436 were MSM, and 191 were ART experienced. Overall, 62.8% of ART-experienced participants and 14.4% of ART-naive participants were found to have low-level resistance or higher to 1 or more classes of drugs. Prevalence of tenofovir disoproxil fumarate resistance was 25.7% in ART-experienced participants and 1.11% in ART-naive participants. The highest proportion of drug resistance was seen across nucleoside reverse transcriptase inhibitors and nonnucleoside reverse transcriptase inhibitors, and resistance was significantly more common among MSM participants than PWID. Phylogenetic analyses revealed that 54.6% of ART-naive participants with resistance who clustered had shared DRMs, suggesting transmitted resistance may have occurred.ConclusionsPatients experiencing virologic failure on first-line therapy switched blindly to tenofovir/lamivudine/dolutegravir may effectively be receiving dolutegravir monotherapy due to resistance to tenofovir and lamivudine. While dolutegravir is expected to have full activity in the majority of patients in India, follow-up is needed to understand how resistance may affect long-term outcomes.

Genotypic Resistance Testing of HIV-1 DNA in Peripheral Blood Mononuclear Cells.

HIV-1 DNA exists in nonintegrated linear and circular episomal forms and as integrated proviruses. In patients with plasma viremia, most peripheral blood mononuclear cell (PBMC) HIV-1 DNA consists of recently produced nonintegrated virus DNA while in patients with prolonged virological suppression (VS) on antiretroviral therapy (ART), most PBMC HIV-1 DNA consists of proviral DNA produced months to years earlier. Drug-resistance mutations (DRMs) in PBMCs are more likely to coexist with ancestral wild-type virus populations than they are in plasma, explaining why next-generation sequencing is particularly useful for the detection of PBMC-associated DRMs. In patients with ongoing high levels of active virus replication, the DRMs detected in PBMCs and in plasma are usually highly concordant. However, in patients with lower levels of virus replication, it may take several months for plasma virus DRMs to reach detectable levels in PBMCs. This time lag explains why, in patients with VS, PBMC genotypic resistance testing (GRT) is less sensitive than historical plasma virus GRT, if previous episodes of virological failure and emergent DRMs were either not prolonged or not associated with high levels of plasma viremia. Despite the increasing use of PBMC GRT in patients with VS, few studies have examined the predictive value of DRMs on the response to a simplified ART regimen. In this review, we summarize what is known about PBMC HIV-1 DNA dynamics, particularly in patients with suppressed plasma viremia, the methods used for PBMC HIV-1 GRT, and the scenarios in which PBMC GRT has been used clinically.

Prevalence of resistance mutations associated with integrase inhibitors in therapy-naive HIV-positive patients in Baoding, Hebei province, China.

Antiretroviral therapy (ART) regimens containing integrase strand transfer inhibitors (INSTIs) are the recommended treatment for human immunodeficiency virus type 1 (HIV-1)-infected patients in the most recent guidelines in China. In this study, we investigated INSTI resistance mutations in newly diagnosed therapy-naive HIV-positive patients in Baoding City, Hebei Province (China) to provide guidance for implementing routine INSTI-associated HIV-1 genotypic resistance testing. Plasma samples were collected from HIV-1-infected patients without treatment at Baoding People’s Hospital from January 2020 to December 2021. The part of HIV-1 pol gene encoding integrase was amplified, sequenced, and analyzed for INSTI resistance. Clinical data including demographic data, CD4+ T cell counts, HIV-RNA loads, and resistance mutations were collected. Treatment-naïve HIV-1 patients (n = 131) were enrolled. We identified ten genotypes, and the predominant genotype was CRF01_AE in 67 patients (51.15%), CRF07_ BC in 39 patients (29.77%), subtype B in 11 patients (8.40%), and other subtypes (CRF68_01B, 3.82%; CRF55_01B, 1.53%, CRF80_0107, 1.53%; URFs 1.53%; and CRF103_01B, CRF59_01B, and CRF65_cpx, 1.4% each). Four major (E138A, R263k, G140S, and S147G) and three accessory (H51Y, Q146QL, and S153F) INSTI-resistance mutations were observed (genotype CRF01_AE, three patients; genotype B, one patient; and genotype CRF07_BC, one patient), resulting in different degrees of resistance to the following five INSTIs: raltegravir, elvitegravir, dolutegravir, bictegravir, and cabotegravir. The overall resistance rate was 3.82% (5/131). All INSTI-resistant strains were cross-resistant. The primary INSTI drug resistance rate among newly diagnosed HIV-infected patients in Baoding was low, but monitoring and research on HIV INSTI resistance should be strengthened in Baoding because INSTI-based regimen prescriptions are anticipated to increase in the near future.

A public health approach to monitoring HIV with resistance to HIV pre-exposure prophylaxis

BackgroundThe risk of HIV pre-exposure prophylaxis (PrEP) failure with sufficient medication adherence is extremely low but has occurred due to transmission of a viral strain with mutations conferring resistance to PrEP components tenofovir (TDF) and emtricitabine (FTC). The extent to which such strains are circulating in the population is unknown.MethodsWe used HIV surveillance data to describe primary and overall TDF/FTC resistance and concurrent viremia among people living with HIV (PLWH). HIV genotypes conducted for clinical purposes are reported as part of HIV surveillance. We examined the prevalence of HIV strains with mutations conferring intermediate to high level resistance to TDF/FTC, defining primary resistance (predominantly K65R and M184I/V mutations) among sequences reported within 3 months of HIV diagnosis and total resistance for sequences reported at any time. We examined trends in primary resistance during 2010–2019 and total resistance among all PLWH in 2019. We also monitored resistance with viremia (≥1,000 copies/mL) at the end of 2019 among PLWH.ResultsBetween 2010 and 2019, 2,172 King County residents were diagnosed with HIV; 1,557 (72%) had a genotypic resistance test within three months; three (0.2%) had primary TDF/FTC resistance with both K65R and M184I/V mutations. Adding isolated resistance for each drug resulted in 0.3% with primary TDF resistance and 0.8% with primary FTC resistance. Of 7,056 PLWH in 2019, 4,032 (57%) had genotype results, 241 (6%) had TDF/FTC resistance and 15 (0.4% of those with a genotype result) had viremia and TDF/FTC resistance.ConclusionsPrimary resistance and viremia combined with TDF/FTC resistance are uncommon in King County. Monitoring trends in TDF/FTC resistance coupled with interventions to help ensure PLWH achieve and maintain viral suppression may help ensure that PrEP failure remains rare.

High-level resistance to non-nucleos(t)ide reverse transcriptase inhibitor based first-line antiretroviral therapy in Ghana; A 2017 study.

Expanding access to effective antiretroviral therapy (ART) is a major tool for management of Human Immunodeficiency Virus (HIV) infection. However, rising levels of HIV drug-resistance have significantly hampered the anticipated success of ART in persons living with HIV (PLWH), particularly those from Africa. Though great strides have been made in Ghana toward achieving the UNAIDS “95-95-95” target, a substantial number of PLWH receiving ART have not attained viral suppression. This study investigated patterns of drug resistance mutations in ART naïve as well as ART-experienced PLWH receiving first-line regimen drugs from Ghana. In a cross-sectional study, blood samples were collected from HIV-1 infected adults (≥18 years) attending HIV/AIDS clinic at the Eastern Regional Hospital, Koforidua, Ghana from September to October 2017. Viral RNA isolated from plasma were subjected to genotypic drug resistance testing for Protease Inhibitors (PI), Reverse Transcriptase Inhibitors (RTI), and Integrase Strand Transfer Inhibitors (INSTI). A total of 95 (84 ART experienced, 11 ART naïve) HIV-1 infected participants were sampled in this study. Sixty percent (50/84) of the ART-experienced participants were controlling viremia (viral load < 1,000 copies/ml). Of the 95 patient samples, 32, 34, and 33 were successfully sequenced for protease, reverse-transcriptase, and integrase regions, respectively. The dominant HIV-1 subtypes detected were CRF02_AG (70%), and A3 (10%). Major drug resistance associated mutations were only detected for reverse transcriptase inhibitors. The predominant drug resistance mutations were against nucleos(t)ide reverse transcriptase inhibitors (NRTI)—M184V/I and non-nucleos(t)ide reverse transcriptase inhibitors (NNRTI)—K103N. In the ART-experienced group, M184V/I and K103N were detected in 54% (15/28) and 46% (13/28) of individuals, respectively. Both mutations were each detected in 33% (2/6) of ART naïve individuals. Multiclass resistance to NRTI and NNRTI was detected in 57% of ART-experienced individuals and two ART naïve individuals. This study reports high-level resistance to NNRTI-based antiretroviral therapy in PLWH in Ghana. However, the absence of major PI and INSTI associated-mutations is a good signal that the current WHO recommendation of Dolutegravir in combination with an NRTI backbone will yield maximum benefits as first-line regimen for PLWH in Ghana.

Virological efficacy of switch to DTG plus 3TC in a retrospective observational cohort of suppressed HIV-1 patients with or without past M184V: the LAMRES study

The aim of this study was to assess the efficacy of dolutegravir plus lamivudine (DTG+3TC) in a large set of virologically suppressed HIV-1 infected individuals with or without past M184V mutation. This observational study included individuals who switched to DTG+3TC with ≥1 genotype before switch. Survival analysis was used to evaluate the role of past M184V on virological rebound (VR) or blips after DTG+3TC switch. A total of 712 individuals followed in several clinical centres in France, Italy and Spain were analysed. Past M184V was present in 60 (8.4%) individuals. By 3 years after switch, the overall probability of VR and blips was 6.7% and 6.9%, respectively, without any statistical significance according to the presence/absence of past M184V. A significantly higher probability of VR was found in individuals harbouring M184V before DTG+3TC with a duration of virological suppression (Ts) ≤.3.5 years compared to others (M184V+Ts ≤.3.5 years: 22.7%; M184M+Ts ≤.3.5 years: 9.0%; M184V+Ts >3.5 years: 7.8%; M184M+Ts >3.5 years: 4.9%; P=0.007). This finding was not confirmed in multivariable models adjusting for behavioural and demographic variables. Genotypic resistance test after VR under DTG+3TC was available for 8/39 individuals; one poorly adherent individual developed M184V. No resistance to INIs was found. In this retrospective observational study, the probability of VR and blips in patients switching to DTG+3TC was very low after 3 years of treatment regardless M184V. The effect of a short duration of previous virological suppression in individuals with M184V remains troubling and needs ad hoc clinical trials to be confirmed.

Real-life use of Doravirine in treatment-experienced people living with HIV: A multicenter Italian study.

Use of doravirine (DOR), a new nonnucleoside reverse-transcriptase inhibitors recently approved for HIV treatment, is still unclear in clinical practice and real-life data are scarce.We retrospectively investigated the rationale for switching people with HIV to DOR-containing/-based regimens in a real-life cohort. Among 132 patients (68.9% males, median age 56 years), the main reasons to start DOR were prevention of toxicities (39.4%) and dyslipidemia (18.2%). DOR was combined with integrase inhibitors in 40.9% cases, and in 25.7% of patients, DOR was prescribed without availability of a genotypic resistance test.Twenty-four weeks after the switch to DOR-containing/-based regimens, no significant changes in CD4+ T-cell count, CD4/CD8 ratio, detectable HIV-RNA, serum creatinine levels, and body weight were detected. By contrast, a significant reduction in lipids (both cholesterol and triglycerides) was observed in 52 patients for whom a follow-up assessment was available (P = .008 and .01, respectively).Our data confirmed that switching to DOR-containing/-based regimens may have a favorable impact on lipid profile and a neutral impact on weight gain. However, more data are needed to support its use in patients who do not have a genotypic test available or have an extensive nonnucleoside reverse-transcriptase inhibitors-associated resistance, as well as its use in a dual regimen, especially in combination with second-generation integrase inhibitors.

Overview of the Analytes Applied in Genotypic HIV Drug Resistance Testing.

The close monitoring of HIV drug resistance using genotypic HIV drug resistance testing (HIVDRT) has become essential for effective HIV/AIDS management at both individual and population levels. Over the years, a broad spectrum of analytes or specimens have been applied or attempted in HIVDRT; however, the suitability and performance of these analytes in HIVDRT and the clinical relevance of the results from them may vary significantly. This article provides a focused overview of the performance, strengths, and weaknesses of various analytes while used in HIVDRT, which may inform the optimal analytes selection in different application contexts.

Are we ready for long-acting? A feasibility evaluation of long-acting cabotegravir-rilpivirine in clinical practice.

Cabotegravir and rilpivirine are the first drugs to be approved as injectable therapy to treat individuals with HIV. Despite encouraging results, the guidelines specify strict criteria for eligibility that could limit the feasibility of this strategy. We collected the clinical data of HIV-positive patients who were being treated at a single, third-level center in Italy. All patients were on stable therapy and showed suppressed viral load on their most recent analyses. We performed a cross-sectional analysis of the clinical and viro-immunological characteristics of this population and excluded patients whohad previous virological failures, resistance-associated mutations(RAMs) to rilpivirine or integrase inhibitors in the historical genotype, hepatitis B infection, absence of previous genotypes, and the coexistence of HIV-subtype A and obesity. Our aim was to evaluate the proportion of patients who could be eligible for switching to this strategy. one thousand seven hundred fifty-twopatients were eligible. One hundred and forty-eightwere excluded because of a detectable viral load. With regard to the exclusion criteria, 48 patients had coinfection with hepatitis B virus, and 744 had a history of previous virological failures. Of the 896 patients with at least one genotypic resistance test, 161 had one or more RAMs to rilpivirine and 3 had RAMs to cabotegravir. None of the patients presented the combination of obesity and the A viral subtype. Overall, 31.2% of the patients were ineligible for cabotegravir-rilpivirine, and the proportion increased to 47.3% when we considered only patients with all available information concerning resistance tests. Approximately half of our cohort of patients did not fulfill the criteria and even more patients were potentially ineligible for cabotegravir-rilpivirine due to the lack of genotypic resistance tests. Also, fertile women had to be excluded due to the lack of data about this combination during pregnancy and breastfeeding.

Molecular Characterization of the pol Gene of Vertically Transmitted HIV-1 Strains in Children with Virological Failure.

HIV-1 pol gene sequences were analyzed from 77 HIV-1 positive children infected perinatally and exhibiting virological failure (VF). Viral subtyping, phylogenetic analysis, and genotypic drug resistance analysis were carried out on samples collected before start of anti retroviral treatment (ART) (baseline, BL), and at 12 months post-ART initiation (M12). Subtype C was found to be most predominant, seen in 75 of the 77 (97.4%) children. The level of pretreatment drug resistance (PDR) was 14% among these children. At BL, K103N (5), E138A/G (4), and M184V (3) were the most common mutations. At M12 the prevalence of any resistance-associated mutation (RAM) (acquired drug resistance/ADR) was 81.8% (63/77). Dual class resistance mutations were seen in 64% (49/77) of children. M184V/I, K103N/S, and Y181C were the most commonly occurring mutations, seen in 76%, 51%, and 36% children. RAMs to the second-generation non-nucleoside reverse transcriptase inhibitors (NNRTI), etravirine (ETR) and rilpivirine (RPV), were seen in 40.2% (31/77) and 48.05% (37/77) of the children, respectively. Our findings reveal similar prevalence rates of PDR and ADR in children with VF as reported in other studies. Occurrence of ETR and RPV resistance associated mutations (RAMs) is of concern and highlights the need for timely switch of regimens guided by genotypic resistance testing in perinatally infected children from India.

New Aspects of the Virus Life Cycle and Clinical Utility of Next Generation Sequencing based HIV-1 Resistance Testing in the Genomic, the Proviral, and the Viral Reservoir of Peripheral Blood Mononuclear Cells.

Typically, genotypic resistance testing is recommended at the start of antiretroviral therapy and is even mandatory in cases of virologic failure. The material of choice is plasma viral RNA. However, in patients with low viremia (viral load < 500 copies/ml), resistance testing by population-based sequencing is very difficult. Therefore, we aimed to investigate whether next generation sequencing (NGS) from proviral DNA and RNA could be an alternative. EDTA blood samples (n = 36) from routine clinical viral load testing were used for the study. Viral loads ranged from 96 to 390,000 copies/mL, with 100% of samples having low viremia. Distribution of subtypes; A (n = 2), B (n = 16), C (n = 4), D (n = 2), G (1), CRF02 AG (n = 5), CRF01 AE (n = 5), undefined/mixed (n = 4). The extracted consensus sequences were uploaded to the Stanford HIV Drug Resistance Data Base and Geno2pheno for online analysis of drug resistance mutations and resistance factors. A total of 2476 variants or drug resistance mutations (DRMs) were detected with Sanger sequencing, compared with 2892 variants with NGS. An average of 822/1008 variants were identified in plasma viral RNA by Sanger or NGS sequencing, 834/956 in cellular viral RNA, and 820/928 in cellular viral DNA. Both methods are well suited for the detection of HIV substitutions or drug resistance mutations. Our results suggest that cellular RNA or cellular viral DNA is an informative alternative to plasma viral RNA for variant detection in patients with low viremia, as shown by the high correlation of variants in the different viral pools. We show that by using UDS, a plus of two DRMs per patient becomes visible, which can make a big difference in the assessment of the expected resistance behavior of the virus.

High Rates of Asymptomatic Mycoplasma genitalium Infections With High Proportion of Genotypic Resistance to First-Line Macrolide Treatment Among Men Who Have Sex With Men Enrolled in the Zurich Primary HIV Infection Study.

Background Mycoplasma genitalium (Mg) is an emerging sexually transmitted pathogen among men who have sex with men (MSM). Resistance to recommended antimicrobial agents are of public health concern. Few data exist on Mg infections in MSM diagnosed with human immunodeficiency virus (HIV) during primary HIV infection.MethodsParticipants of the Zurich Primary HIV Study (ClinicalTrials.gov Identifier NCT 00537966) were systematically offered screening for sexually transmitted infections (STIs) between April 2019 and September 2020. Screening was performed using an in-house polymerase chain reaction panel comprising Mg including genotypic resistance testing for macrolides and quinolones, Chlamydia trachomatis including serovars L1-L3, Neisseria gonorrhoeae, Treponema pallidum, and Hemophilus ducreyi.ResultsWe screened 148 of 266 (55.6%) participants, with an overall total of 415 follow-up visits. Ninety-one percent were MSM. The incidence rate for all STIs was 47.0 (95% confidence interval [CI], 32.2–68.6) per 100 person-years. Mycoplasma genitalium was the most frequently detected pathogen: 30 participants (20%) presented with at least 1 Mg infection, corresponding to a period prevalence of 20.3% and incidence rate of 19.5 Mg infections (95% CI, 11.8–32.4). Most Mg infections (93%) were asymptomatic, and 9 (30%) participants showed spontaneous clearance. We detected high rates of antibiotic resistance: 73.3% to macrolides, 3.3% to quinolones, and 13.3% resistance to both antibiotics.ConclusionsThe high prevalence of mostly asymptomatic Mg infections and high rate of spontaneous clearance support cautious initiation for treatment. The high proportion of macrolide-resistant strains suggests that a genotypic determination of resistance should be standard of care. Moxifloxacin should be the preferred treatment option for symptomatic Mg infections among MSM if resistance testing is unavailable.

High Rate of HIV-1 Drug Resistance in Antiretroviral Therapy-Failure Patients in Liaoning Province, China.

This study aimed to monitor the prevalence of HIV-1 drug resistance and risk factors associated with drug resistance in antiretroviral therapy (ART)-failure individuals in Liaoning Province, China. Plasma samples were collected from HIV-1-positive individuals who experienced ART failure in Liaoning Province between April 2018 and September 2019. Genotype resistance test was performed using an in-house assay on these collected samples. Factors associated with drug resistance were identified by logistic regression analysis. We collected a total of 468 ART-failure individuals, of which 256 were successfully included in the final study. Of these, the most predominant genotype was CRF01_AE, accounting for 77.73%. The resistance rate to any of the three classes of antiretroviral drugs (non-nucleoside reverse transcriptase inhibitors [NNRTIs], nucleoside reverse transcriptase inhibitors [NRTIs], and protease inhibitors [PIs]) was 64.84%. Among 256 ART-failure patients, 62.89% showed drug resistance to NNRTIs, 50.39% to NRTIs, and 3.13% to PIs. G190S (31.25%) and Y181C (25.78%) mutations were the most common NNRTIs resistance mutations. K65R (29.69%), M184V (28.52%) were the most common NRTIs resistance mutations. Factors associated with drug resistance included current ART regimen and viral load. The high drug resistance rate among ART-failure individuals in Liaoning Province needs more attention. Corresponding strategies for the risk factors associated with HIV drug resistance can better control and prevent the prevalence of resistance.

Early versus delayed antiretroviral therapy based on genotypic resistance test: Results from a large retrospective cohort study.

Rapid start of antiretroviral therapy (ART) pending genotypic resistance test (GRT) has been recently proposed, but the effectiveness of this strategy is still debated. The rate of virological success (VS), defined as HIV‐RNA < 50 copies/ml, with and without GRT was compared in drug‐naïve individuals enrolled in the Italian ARCA cohort who started ART between 2015 and 2018. 521 individuals started ART: 397 without GRT (pre‐GRT group) and 124 following GRT (post‐GRT group). Overall, 398 (76%) were males and 30 (6%) were diagnosed with AIDS. In the pre‐GRT group, baseline CD4+ cell counts were lower (p < 0.001), and viral load was higher (p < 0.001) than in the post‐GRT group. The estimated probability of VS in pre‐GRT versus post‐GRT group was 72.54% (CI95: 67.78–76.60) versus 66.94% (CI95: 57.53–74.26) at Week 24 and 92.40% (CI95: 89.26–94.62) versus 92.92% (CI95: 86.35–96.33) at Week 48, respectively (p = 0.434). At Week 48, VS was less frequent among individuals with baseline CD4+ cell counts <200 versus >500 (90.33% vs. 97.33%), log viral load <5.00 versus >5.70 log10 cps/ml (97.17% vs 78.16%; p < 0.001), and those treated with protease inhibitors or non‐nucleoside reverse transcriptase inhibitors versus those treated with integrase strand transfer inhibitors (p < 0.001). The rate of VS does not seem to be affected by an early ART initiation pending GRT results, but it could be influenced by the composition of the ART regimen, as well as immuno‐virological parameters.

Bovine mastitis in northeastern Brazil: Occurrence of emergent bacteria and their phenotypic and genotypic profile of antimicrobial resistance

The aim of this study was to identify emergent pathogens associated with bovine mastitis in northeastern Brazil and to characterize them for phenotypic and genotypic resistance to antimicrobials. A total of 321 milk samples from cows with subclinical mastitis were collected, and the isolates obtained in culture were identified using matrix-associated laser desorption-ionization - time of flight mass spectrometry. Phenotypic and genotypic antimicrobial resistance tests were performed. We identified 72 bacteria considered emergent in the study region: Enterococcus faecalis (26.3%; 19/72), Streptococcus agalactiae (22.2%; 16/72), Enterococcus faecium (20.0%; 15/72), Escherichia coli (6.9%; 5/72), 6.9% (5/72) Lactococcus garvieae (6.9%; 5/72), Acinetobacter baumannii (5.5%; 4/72), Bacillus subtilis (1.3%; 1/72), Kocuria marina (1.3%; 1/72), Macrococcus caseolyticus (1.3%; 1/72), Microbacterium resistens (1.3%; 1/72), Micrococcus luteus (1.3%; 1/72), Streptococcus dysgalactiae (1.3%; 1/72), Streptococcus hyovaginalis (1.3%; 1/72) and Streptococcus pluranimalium (1.3%; 1/72). The antibiogram revealed the following resistance profiles: ampicillin (77.7%; 56/72), cefoxitin (69.4%; 50/72), erythromycin (61.1%; 44/72), oxacillin (63.8%; 46/72), penicillin (79.1%; 57/72), tetracycline (63.8%; 46/72), gentamicin (25.0%; 18/72), and vancomycin (20.8%; 15/72). Of the isolates, 83.4% (60/72) showed multiple resistance to antimicrobials. The tetM gene was identified in 43.0% (31/72) of the isolates, followed by tetL (31.9%; 23/72), and blaZ (26.3%; 19/72). 83.4% (60/72) of the isolates presented a multiple antimicrobial resistance index higher than 0,2. Emergent bacteria with zoonotic and multiresistant potential occur in cows with mastitis in northeastern Brazil. It is necessary to monitor the occurrence of these and other bacteria in livestock environments and develop control strategies to prevent their spread.

Virological and Immunological Outcomes of an Intensified Four-Drug versus a Standard Three-Drug Antiretroviral Regimen, Both Integrase Strand Transfer Inhibitor-Based, in Primary HIV Infection.

The optimal therapeutic approach for primary HIV infection (PHI) is still debated. We aimed to compare the viroimmunological response to a four- versus a three-drug regimen, both INSTI-based, in patients with PHI. This was a monocentric, prospective, observational study including all patients diagnosed with PHI from December 2014 to April 2018. Antiretroviral therapy (ART) was started, before genotype resistance test results, with tenofovir/emtricitabine and either raltegravir plus boosted darunavir or dolutegravir. Cumulative probability of virological suppression [VS] (HIV-1 RNA< 40 cp/mL), low-level HIV-1 DNA [LL-HIVDNA] (HIV-1 DNA < 200 copies/106PBMC), and CD4/CD8 ratio ≥1 were estimated using Kaplan–Meier curves. Factors associated with the achievement of VS, LL-HIVDNA, and CD4/CD8 ≥ 1 were assessed by a Cox regression model. We enrolled 144 patients (95.8% male, median age 34 years): 110 (76%) started a four-drug-based therapy, and 34 (24%) a three-drug regimen. Both treatment groups showed a comparable high probability of achieving VS and a similar probability of reaching LL-HIVDNA and a CD4/CD8 ratio ≥1 after 48 weeks from ART initiation. Higher baseline HIV-1 RNA and HIV-1 DNA levels lowered the chance of VS, whereas a better preserved immunocompetence increased that chance. Not statistically significant factors associated with LL-HIVDNA achievement were found, whereas a higher baseline CD4/CD8 ratio predicted the achievement of immune recovery. In PHI patients, the rapid initiation of either an intensified four-drug or a standard three-drug INSTI-based regimen showed comparable responses in terms of VS, viral reservoir size, and immunological recovery.

Achieving virological control in pan-resistant HIV-1 infection: A case series.

SummaryBackgroundHIV-1 pan-resistance refers to a reduced susceptibility to nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitors and integrase strand tranfer inhibitors. Although still anecdotal, its management remains a concern both for affected people living with HIV (PLWH) and for public health.MethodsWe described genotypic resistance testing (GRT) of three PLWH with a documented poor virological response to previous antiretroviral therapies, who started ibalizumab, an anti-CD4 monoclonal antibody, combined with an optimized background therapy. Both historical and most recent GRT on plasma RNA and peripheral blood mononuclear cell DNA were interpreted according to the Stanford HIVDb version 9.0 (last updated on 22 February, 2021). After the switch to a regimen including the monoclonal antibody, HIV-1 RNA has been quantified biweekly (PCR Cobas® HIV-1 test 6800 Systems, Roche Diagnostics). Follow-up was censored at data freezing (16 January, 2021).FindingsWe report findings from heavily treatment-experienced PLWH with a pan-resistant HIV-1 infection, who achieved virological control once introduced injections of ibalizumab, that is free from cross-resistance with all the antiretroviral drugs available and ensures patient adherence due to a close monitoring attributable to the route of administration, combined with recycled enfuvirtide and an optimized background regimen, selected on the basis of an accurate evaluation of resistance mutations.InterpretationIn these cases, this new approach has revealed to be a turning point in achieving virological control.FundingNone, this research was supported by internal funding.

Pre-treatment and acquired antiretroviral drug resistance among people living with HIV in Tianjin, China.

This study investigated the prevalence and patterns of pre-treatment and acquired HIV drug resistance mutations among people living with HIV (PLWH) on antiretroviral therapy (ART) for 12 (±3) months in Tianjin, China. From Jan 2018 to Dec 2020, PLWH with HIV-1 RNA greater than 1000 copies/mL visiting the ART clinic in the Tianjin Second People's Hospital were enrolled. Viral RNA isolated from blood samples were taken for genotypic resistance testing using an in-house method. Major drug resistance mutations were analyzed for reverse transcriptase and protease Sanger sequences using the Stanford University HIV Drug Resistance Database. Multivariable Poisson regressions were used to evaluate the factors associated with drug resistance mutations. HIV drug resistance testing was successfully performed on 584 ART-naive and 71 ART-experienced participants. Pre-treatment drug resistance mutation prevalence was 13.5% (79/584) to any antiretroviral drug, 12.5% (73/584) to non-nucleoside reverse transcriptase inhibitors (NNRTIs), 1.5% (9/584) to nucleoside reverse-transcriptase inhibitors (NRTIs), and 0.3% (2/584) to protease inhibitors (PIs). Acquired drug resistance to any antiretroviral drug among PLWH on ART with viral load >1000 copies/mL was 88.7% (63/71). The prevalence of mutation for NNRTIs, NRTIs, and PIs were 93.7% (59/63), 82.5% (52/63), and 3.2% (2/63), respectively. Pre-treatment and acquired drug resistance mutations were highly prevalent among PLWH in Tianjin; therefore, routine baseline genotypic resistance testing and adequate intervals of viral load surveillance are urgently needed for the long-term treatment success. Our findings provide important evidence for first- and second-line regimen drugs for PLWH, especially in China.

Predictors of Virological Failure Among People Living with HIV Switching from an Effective First-Line Antiretroviral Regimen.

Aim of this study was to assess the predictors of virological failure (VF) among patients living with HIV (PLWHIV) switching from an effective first-line antiretroviral therapy (ART) regimen, and to evaluate the emergence of resistance-associated mutations. All adult patients enrolled in the Antiviral Response Cohort Analysis cohort who started ART after 2010, with at least 6 months of virological suppression (VS) before ART switch and with an available genotypic resistance test (GRT) at baseline were included. Thirty-two patients out of the 607 PLWHIV included (5.3%) experienced VF after a median of 11 months from ART switch. Younger age (adjusted Hazard Ratio [aHR] 0.96, 95% confidence interval [CI] 0.92-0.99, p = .023), being male who have sex with male (aHR 0.15, 95% CI 0.03-0.69, p = .014), and longer time from VS to ART switch (aHR 0.97, 95% CI 0.95-1.00, p = .021) resulted protective toward VF, while receiving a first-line regimen containing a backbone other than ABC/3TC or TXF/FTC (aHR 3.61, 95% CI 1.00-13.1, p = .050) and a boosted protease inhibitor as anchor drug (aHR 3.34, 95% CI 1.20-9.28, p = .021) were associated with higher risk of VF. GRT at the moment of VF was available only for 13 patients (40.6%). ART switch in patients with stable control of HIV infection is a safe practice, even if particular attention should be paid in certain cases of patients switching from regimens containing low-performance backbones or protease inhibitors.