Occurrence of extended-spectrum β-lactamase, AmpC, and carbapenemase-producing genes in gram-negative bacterial isolates from human immunodeficiency virus infected patients

BACKGROUND

Progressive decline of immune response in HIV patients makes them susceptible to frequent bacterial infections. High usage of antibiotics influences the emergence of multidrug-resistant bacteria and worsens the clinical outcomes. In this study, the occurrence of drug-resistant genes in Gram-negative bacterial isolates from HIV patients in South India was analyzed.

METHODS

A total of 173 Gram-negative bacterial (GNB) isolates from HIV patients were screened for antibiotic susceptibility profile using the Kirby-Bauer diskdiffusion method. Positivity of drug-resistant genes was analyzed using polymerase chain reaction method.

RESULTS

In this study, 72.8% of bacterial isolates were obtained from urine specimens, and Escherichia coli (47.4%) was the predominantly isolated bacterium. Overall, 87.3% and 83.2% of GNB were resistant to 3rd generation cephalosporin antibiotics such as cefotaxime and ceftazidime, respectively, 56.6% were resistant to cephamycin (cefoxitin) and 43% to carbapenem (imipenem) antibiotics. Extended-spectrum β-lactamases (ESBL) production was noted among 79.5% of GNB isolates, followed by AmpC (57.1%) and Metallo β-lactamases (37.3%). Molecular analysis revealed that ESBL genes such as blaTEM (94.1%), blaCTX-M (89.2%), and blaSHV (24.2%) were detected at higher levels among GNB isolates. Carbapenemase-producing genes such as blaOXA-48 (20%), blaOXA-23 (2.6%), and both blaOXA-23 and blaOXA-51 like genes (2.6%) and AmpC producing genes such as blaCIT (26.7%), blaDHA (3.6%), and blaACC (1.8%) were detected at low-level.

CONCLUSIONS

This study concludes that ESBL producing genes are detected at high level among gram-negative bacterial isolates from HIV patients in South India.

Association of circulatory Tfh-like cells with neutralizing antibody responses among chronic HIV-1 subtype C infected long-term nonprogressors and progressors

HIV-1 vaccine functioning relies on successful induction of broadly neutralizing antibodies (bNAbs). CXCR3- circulatory T-follicular helper (cTfh) cells are necessary for inducing B-cells for generating bNAbs. Recent studies have suggested that CXCR3+ Tfh cells might also influence bNAb production. Plasma samples from 34 ART-Naïve HIV-1 infected individuals [long-term nonprogressors (LTNP)-19; Progressors-13] were tested against a heterologous virus panel (n = 11) from subtypes A, B, C, G, AC, BC and AE. Frequencies of CXCR3+ and CXCR3- cTfh-like cells in peripheral circulation were studied using flow cytometry. LTNP showed significantly lower CXCR3+ and higher CXCR3- cTfh-like cell frequencies, while neutralization breadth was observed to be broader in progressors. A positive correlation was observed between bNAb breadth and potency with CXCR3+PD-1+ cTfh-like cells in LTNP. Based on neutralization breadth, 9 HIV-1 infected individuals were classified as 'top neutralizers' and 23 as 'low neutralizers' and they did not show any correlations with CXCR3+ and CXCR3- cTfh-like cells. These preliminary data suggest that CXCR3+ similar to CXCR3- might possess significant functional properties for driving B-cells to produce bNAbs. Hence, an HIV vaccine which is capable of optimal induction of CXCR3+ cTfh cells at germinal centers might confer superior protection against HIV.

HIV-specific T-cell Responses and Generalized Activation in HIV-1 Infected Long-term Non-progressors and Progressors from South India

Background:

Anti-viral cytokine expressions by cytotoxic T-cells and lower activation rates have been reported to correlate with suppressed HIV replication in long-term non-progressors (LTNP). Immune mechanisms underlying disease non-progression in LTNP might vary with HIV-1 subtype and geographical locations.

Objective:

This study evaluates cytokine expression and T-cells activation in relation to disease non-progression in LTNP.

Methods:

HIV-1 Subtype C infected LTNP (n=20) and progressors (n=15) were enrolled and flowcytometry assays were performed to study HIV-specific CD8 T-cells expressing IL-2, IFN-γ, TNF-α and MIP-1β against gag and env peptides. CD4+ T-cell activation was evaluated by surface expression of HLADR and CD38.

Results:

Proportions of cytokines studied did not differ significantly between LTNP and progressors, while contrasting correlations with disease progression markers were observed in LTNP. CD4+ T-cell activation rates were significantly lower in LTNP compared to progressors which indicate the potential role of T-cell activation rates in disease non-progression in LTNP.

Conclusion:

LTNP and progressors showed similar CD8+ T-cell responses, but final conclusions can be drawn only by comparing multiple immune factors in larger LTNP cohort with HIV-1 infected individuals at various levels of disease progression. A possible role of HIV-1 subtype variation and ethnic differences in addition to host-genetic and viral factors cannot be ruled out.

Changing drug resistance profile in Pseudomonas aeruginosa infection among HIV patients from 2010-2017: A retrospective study

OBJECTIVES

Pseudomonas aeruginosa is an important aetiological agent causing pneumonia, urinary tract infections and bacteraemia. High antibiotic use in nosocomial settings and for immunocompromised conditions results in increasing multidrug resistance. This study analysed the antimicrobial resistance profile of P. aeruginosa isolates in an HIV setting.

METHODS

A total of 7386 clinical specimens were collected from HIV patients attending YRG CARE from 2010-2017. P. aeruginosa isolated from clinical specimens were identified conventionally, and antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method.

RESULTS

A total of 260 P. aeruginosa strains were isolated, with 165 P. aeruginosa (63.5%) being isolated from hospitalised patients. A higher incidence of P. aeruginosa infection (25.8%) was observed in 2017, and most of the P. aeruginosa were isolated from sputum specimens (57.3%). A high level of resistance was noted to ceftazidime (49.6%), followed by ticarcillin (41.5%). Imipenem and meropenem resistance was observed in 15.0% and 16.9% of P. aeruginosa isolates, respectively. A high rate of imipenem resistance was noted in 2016 (46.2%) and a high rate of meropenem resistance was noted in 2017 (20.5%). An increasing resistance rate of P. aeruginosa was observed against aztreonam, cefepime, levofloxacin, meropenem, piperacillin, piperacillin/tazobactam, ticarcillin and tobramycin from 2010 to 2017.

CONCLUSION

A constant increase in drug-resistant P. aeruginosa isolates from HIV patients was observed from 2010 to 2017. Findings from this study urge the need for periodical monitoring and surveillance of the P. aeruginosa resistance profile, especially in hospitalised and immunocompromised patients in resource-limited settings.

Broad neutralization response in a subset of HIV-1 subtype C-infected viraemic non-progressors from southern India

Broadly neutralizing antibodies (bnAbs) have been considered to be potent therapeutic tools and potential vaccine candidates to enable protection against various clades of human immunodeficiency virus (HIV). The generation of bnAbs has been associated with enhanced exposure to antigen, high viral load and low CD4+ T cell counts, among other factors. However, only limited data are available on the generation of bnAbs in viraemic non-progressors that demonstrate moderate to high viraemia. Further, since HIV-1 subtype C viruses account for more than 50 % of global HIV infections, the identification of bnAbs with novel specificities is crucial to enable the development of potent tools to aid in HIV therapy and prevention. In the present study, we analysed and compared the neutralization potential of responses in 70 plasma samples isolated from ART-naïve HIV-1 subtype C-infected individuals with various disease progression profiles against a panel of 30 pseudoviruses. Among the seven samples that exhibited a neutralization breadth of ≥70 %, four were identified as 'elite neutralizers', and three of these were from viraemic non-progressors while the fourth was from a typical progressor. Analysis of the neutralization specificities revealed that none of the four elite neutralizers were reactive to epitopes in the membrane proximal external region (MPER), CD4-binding site and V1V2 or V3 glycan. However, two of the four elite neutralizers exhibited enhanced sensitivity towards viruses lacking N332 glycan, indicating high neutralization potency. Overall, our findings indicate that the identification of potent neutralization responses with distinct epitope specificities is possible from the as yet unexplored Indian population, which has a high prevalence of HIV-1 subtype C infection.

Performance of point-of-care Xpert HIV-1 plasma viral load assay at a tertiary HIV care centre in Southern India

BACKGROUND

Sustainable suppression of HIV replication forms the basis of anti-retroviral therapy (ART) medication. Thus, reliable quantification of HIV viral load has become an essential factor to monitor the effectiveness of the ART. Longer turnaround-time (TAT), batch testing and technical skills are major drawbacks of standard real-time PCR assays.

METHODS

The performance of the point-of-care Xpert HIV-1 viral load assay was evaluated against the Abbott RealTime PCR m2000rt system. A total of 96 plasma specimens ranging from 2.5 log10 copies ml^-1 to 4.99 log10 copies ml^-1 and proficiency testing panel specimens were used. Precision and accuracy were checked using the Pearson correlation co-efficient test and Bland-Altman analysis.

RESULTS

Compared to the Abbott RealTime PCR, the Xpert HIV-1 viral load assay showed a good correlation (Pearson r=0.81; P<0.0001) with a mean difference of 0.27 log10 copies ml^-1 (95 % CI, -0.41 to 0.96 log10 copies ml^-1; sd, 0.35 log10 copies ml^-1).

CONCLUSION

Reliable and ease of testing individual specimens could make the Xpert HIV-1 viral load assay an efficient alternative method for ART monitoring in clinical management of HIV disease in resource-limited settings. The rapid test results (less than 2 h) could help in making an immediate clinical decision, which further strengthens patient care.

A rapid and low-cost microscopic observation drug susceptibility assay for detecting TB and MDR-TB among individuals infected by HIV in South India

BACKGROUND

The converging epidemics of HIV and tuberculosis (TB) pose one of the greatest public health challenges of our time. Rapid diagnosis of TB is essential in view of its infectious nature, high burden of cases, and emergence of drug resistance.

OBJECTIVE

The purpose of this present study was to evaluate the feasibility of implementing the microscopic observation drug susceptibility (MODS) assay, a novel assay for the diagnosis of TB and multi-drug-resistant tuberculosis (MDR-TB) directly from sputum specimens, in the Indian setting.

MATERIALS AND METHODS

This study involved a cross-sectional, blinded assessment of the MODS assay on 1036 suspected cases of pulmonary TB in HIV-positive and HIV-negative patients against the radiometric method, BD-BACTEC TB 460 system.

RESULTS

Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of the MODS assay in detecting MTB among TB suspected patients were 89.1%, 99.1%, 94.2%, 95.8%, respectively. In addition, in the diagnosis of drug-resistant TB, the MODS assay was 84.2% sensitive for those specimens reporting MDR, 87% sensitivity for those specimens reporting INH mono-resistance, and 100% sensitive for specimens reporting RIF mono-resistance. The median time to detection of TB in the MODS assay versus BACTEC was 9 versus 21 days (P<0.001).

CONCLUSION

Costing 5 to 10 times lesser than the automated culture methods, the MODS assay has the potential clinical utility as a simple and rapid method. It could be effectively used as an alternative method for diagnosing TB and detection of MDR-TB in a timely and affordable way in resource-limited settings.