Trends of Antimicrobial Susceptibility of Neisseria gonorrhoeae isolates between 2012 and 2023: results from an open Italian cohort

BACKGROUND

Neisseria gonorrhoeae (Ng) is a public health priority due to the rapid evolution of antimicrobial resistance, the emergence of antibiotic resistance and the absence of a vaccine against Ng. The aim of this study was to investigate trends in the minimum inhibitory concentration (MIC) and resistance (R) or reduced susceptibility (DS) of Ng cases to ceftriaxone (CRO), azithromycin (AZM), tetracycline (TET), benzylpenicillin (PenG), ciprofloxacin (CIP) over a 10-year period.

METHODS

Retrospective analysis on an open cohort of Ng cases diagnosed on rectal, urethral and pharyngeal samples at San Raffaele Scientific Institute, between September 2012-February 2023. MICs of antibiotics were determined by gradient-test strips. Bivariate linear regression models, applied on logarithmic MICs values; Cochran-Armitage test was used to determine a linear trend in the proportions of resistant strains.

RESULTS

436 Ng isolates from 352 individuals were analyzed. MICs of CRO and PenG reduced over time (p < 0.001, p = 0.030), AZM increased (p = 0.001), CIP and TET did not change (p = 0.473, p = 0.272). The percentages of resistant strains were: PenG 89.9%, TET 90.8%, CIP 48.2%, AZM 4.4%; CRO-DS strains were 8.7%, only one CRO-R. The proportion of resistant strains increased over time for AZM (p = 0.007), TET (p = 0.001), CIP (p < 0.001), whereas decreased for PenG (p < 0.001) and CRO-DS/R strains (p < 0.001).

CONCLUSIONS

Ng strains showed high susceptibility to CRO, although we identified cases of DS/R and observed high levels of susceptibility to AZM. Overall, the recommended primary regimen for Ng treatment confirmed to be effective.

High Propensity to Switch to Long-acting Injectable HIV PrEP with Cabotegravir in a Cohort of Oral PrEP Experienced Men who Have Sex with Men in Italy

Aim was to investigate the propensity to switch to long-acting injectable HIV pre-exposure prophylaxis (PrEP) with cabotegravir among oral PrEP-experienced men who have sex with men. Out of 377 PrEP users, 325 (86.2%) were interested (would like = 210) or considering (would consider = 115) switch to long-acting PrEP. At multivariable analysis, the odds ratio of interest in long-acting PrEP in non-adherent vs. adherent individuals to oral PrEP was 5.03 (95%CI = 1.73-14.61,p = 0.003) and of consideration 1.63 (95%CI = 0.51-5.23,p = 0.410). We observed very high propensity to switch to long-acting PrEP, particularly among non-adherent users. Rapid availability of long-acting PrEP might address unmet needs of PrEP users in Italy.

Impact of predicted HLA class I immunopeptidome on viral reservoir in a cohort of people living with HIV in Italy

The class I HLA genotype has been widely recognized as a factor influencing HIV disease progression in treatment-naïve subjects. However, little is known regarding its role in HIV disease course and how it influences the size of the viral reservoir once anti-retroviral therapy (ART) is started. Here, leveraging on cutting-edge bioinformatic tools, we explored the relationship between HLA class I and the HIV reservoir in a cohort of 90 people living with HIV (PLWH) undergoing ART and who achieved viral suppression. Analysis of HLA allele distribution among patients with high and low HIV reservoir allowed us to document a predominant role of HLA-B and -C genes in regulating the size of HIV reservoir. We then focused on the analysis of HIV antigen (Ag) repertoire, by investigating immunogenetic parameters such as the degree of homozygosity, HLA evolutionary distance and Ag load. In particular, we used two different bioinformatic algorithms, NetMHCpan and MixMHCpred, to predict HLA presentation of immunogenic HIV-derived peptides and identified HLA-B*57:01 and HLA-B*58:01 among the highest ranking HLAs in terms of total load, suggesting that their previously reported protective role against HIV disease progression might be linked to a more effective viral recognition and presentation to Cytotoxic T lymphocytes (CTLs). Further, we speculated that some peptide-HLA complexes, including those produced by the interaction between HLA-B*27 and the HIV Gag protein, might be particularly relevant for the efficient regulation of HIV replication and containment of the HIV reservoir. Last, we provide evidence of a possible synergistic effect between the CCR5 ∆32 mutation and Ag load in controlling HIV reservoir.

Post-neurosurgical Nocardia meningoventriculitis: a case report and review of the literature

The genus Nocardia consists of a group of gram-positive environmental bacteria. They typically cause lung and brain infections in immunocompromised patients, even though one out of three infected patients have a normally functioning immune system. Being a ubiquitous microorganism, in some cases Nocardia has been associated with nosocomial acquired infections and surgical procedures. A review of the literature in this field follows the case report. A 47-year-old woman underwent an endoscopic third ventriculostomy and a left retro-sigmoid craniotomy for a schwannoma removal. Meningeal symptoms began a week later, in association with C reactive protein rise and leukocytosis. Cerebrospinal fluid (CSF) examination was clear with hypoglycorrhachia, hyperprotidorrachia and polymorphonuclear cells. Cultural exam was negative. At the brain magnetic resonance imaging (MRI) purulent material was described in the occipital ventricular horns. Empirical broad spectrum antibiotic therapy was given for 31 days until the brain MRI showed a resolution of the infection. Ten days later, the patient was admitted to the hospital because of new meningeal symptoms. Cerebrospinal fluid culture and Polymerase-chain reaction (PCR) Multiplex for the most important meningitis viruses and bacteria tested negative. A broad-spectrum antibiotic therapy was started with no benefit; thus, a broad-spectrum antifungal therapy was added with little success on clinical status. Meanwhile, a 16s and 18s rRNA PCR was executed on a previous Cerebrospinal fluid with negative results, excluding bacterial and fungal infections. For this reason, all the therapies were stopped. After a few days, high fever and meningeal signs reappeared. The brain MRI showed a meningoventriculitis. An Ommaya catheter with reservoir was inserted and the drawn CSF resulted in the growth of Nocardia farcinica. Antibiogram-based antibiotic therapy was started with intravenous imipenem and trimethoprim-sulfamethoxazole, showing clinical benefit. The patient was sent home with oral linezolid and amoxicillin/clavulanate for a total of 12 months of therapy. Nocardia rarely causes post-neurosurgical complication in a nosocomial setting. This case shows the difficulty in detecting Nocardia and the importance of the correct microbiological sample and antibiogram-based antibiotic therapy to achieve successful treatment.