Infections caused by metallo-β-lactamase (MBL)-producing Enterobacterales and Pseudomonas are increasingly reported worldwide and are usually associated with high mortality rates (>30%). Neither ...standard therapy nor consensus for the management of these infections exist. Aztreonam, an old β-lactam antibiotic, is not hydrolyzed by MBLs. However, since many MBL-producing strains co-produce enzymes that could hydrolyze aztreonam (e.g., AmpC, ESBL), a robust β-lactamase inhibitor such as avibactam could be given as a partner drug. We performed a systematic review including 35 in vitro and 18 in vivo studies on the combination aztreonam + avibactam for infections sustained by MBL-producing Gram-negatives. In vitro data on 2209 Gram-negatives were available, showing the high antimicrobial activity of aztreonam (MIC ≤ 4 mg/L when combined with avibactam) in 80% of MBL-producing Enterobacterales, 85% of Stenotrophomonas and 6% of MBL-producing Pseudomonas. Clinical data were available for 94 patients: 83% of them had bloodstream infections. Clinical resolution within 30 days was reported in 80% of infected patients. Analyzing only patients with bloodstream infections (64 patients), death occurred in 19% of patients treated with aztreonam + ceftazidime/avibactam. The combination aztreonam + avibactam appears to be a promising option against MBL-producing bacteria (especially Enterobacterales, much less for Pseudomonas) while waiting for new antimicrobials.
Ceftazidime/avibactam (CAZ-AVI), approved in 2015, is an important first-line option for Klebsiella pneumoniae carbapenemase-producing Enterobacterales (KPC-E). Although still uncommon, resistance to ...CAZ-AVI has emerged and may represent a serious cause of concern.
We performed a systematic literature review of clinical and microbiological features of infections and colonisations by CAZ-AVI-resistant KPC-E, focused on the in vivo emergence of CAZ-AVI resistance in different clinical scenarios.
Twenty-three papers were retrieved accounting for 42 patients and 57 isolates, mostly belonging to K. pneumoniae ST258 harbouring D179Y substitution in the KPC enzyme. The USA, Greece and Italy accounted for 80% of cases. In one-third of isolates resistance was not associated with previous CAZ-AVI exposure. Moreover, 20% of the strains were colistin-resistant and 80% were extended-spectrum β-lactamase (ESBL)-producers. The majority of infected patients had severe underlying diseases (39% cancer, 22% solid-organ transplantation) and 37% died. The abdomen, lung and blood were the most involved infection sites. Infections by CAZ-AVI-resistant strains were mainly treated with combination therapy (85% of cases), with meropenem being the most common (65%) followed by tigecycline (30%), gentamicin (25%), colistin (25%) and fosfomycin (10%). Despite the emergence of resistance, 35% of patients received CAZ-AVI.
Taken together, these data highlight the need for prompt susceptibility testing including CAZ-AVI for Enterobacterales, at least in critical areas. Resistance to CAZ-AVI is an urgent issue to monitor in order to improve both empirical and targeted CAZ-AVI use as well as the management of patients with infections caused by CAZ-AVI-resistant strains.
We directly tested 484 organisms from clinical (
= 310) and simulated (
= 174) positive blood cultures using the NG-Test Carba 5 assay for carbapenemase-producing
detection. The assay identified ...all but 4 of the KPC (170/171), OXA-48-like (22/22), VIM (19/21), and NDM (14/15) producers with no false positives. Among the clinical
organisms tested, 122 of 123 KPC, 1 of 1 OXA-48-like, and 1 of 2 VIM producers were detected by the assay. Some VIM and NDM producers yielded scant but still-readable bands with the assay. No organisms produced the IMPs that the assay was designed to detect.
We investigated the colistin resistance mechanism in an Escherichia coli strain (LC711/14) isolated in Italy in 2014, from an urinary tract infection, which was previously shown to express a colistin ...resistance mechanism different from mcr-1. LC711/14 was found to carry a novel mutation in the pmrB gene, resulting in a leucine to proline amino acid substitution at position 10 of the PmrB sensor kinase component of the PmrAB signal transduction system. The role of this substitution in colistin resistance was documented by expression of the wild-type and mutated alleles in a pmrB deletion derivative of the E. coli reference strain MG1655, in which expression of the mutated allele conferred colistin resistance and upregulation of the endogenous pmrHFIJKLM lipid A modification system. Complementation of LC711/14 with the wild-type pmrB allele restored colistin susceptibility and decreased expression of pmrHFIJKLM, confirming the role of this PmrB mutation. Substitution of leucine at position 10 of PmrB with other amino acids (glycine and glutamine) resulted in loss of function, underscoring a key role of this residue which is located in the cytoplasmic secretion domain of the protein. This work demonstrated that mutation in this domain of the PmrB sensor kinase can be responsible for acquired colistin resistance in E. coli strains of clinical origin.
Healthcare-associated infections (HAIs) represent a relevant problem for all healthcare facilities, because they involve both the care aspect and the economic management of the hospital. Most HAIs ...are preventable through effective Infection Prevention and Control (IPC) measures. Implementation and improvement of IPC programs are critical to reducing the impact of these infections and the spread of multi-resistant microorganisms. The purpose of this Expert Opinion statement was to provide a practical guide for healthcare organizations, physicians, and nursing staff on the optimal implementation of the core components of Infection Prevention and Control, as recommended by a board of specialists after in-depth discussion of the available evidence in this field. According to their independent suggestions and clinical experiences, as well as evidence-based practices and literature review, this document provides a practical bundle of organizational, structural, and professional requirements necessary to promote, through multimodal strategies, the improvement of the quality and safety of care with respect to infectious risk in order to protect the patient, facilities, and healthcare providers. Keywords: Healthcare-associated infections, Infection prevention and control, IPC core components, Hand hygiene
•Immunity from natural SARS-CoV-2 infection is protective in healthcare workers•Secondary infection is associated with low or absent serum neutralizing titer•Anti-Spike IgG were not significantly ...lower in subjects with secondary infections•Secondary infection is usually asymptomatic or mildly symptomatic•Vaccination of SARS-CoV-2-seronegative subjects might be prioritized
The protection from SARS-CoV-2 infection induced by SARS-CoV-2 anti-S1 and anti-S2 IgG antibody positivity resulting from natural infection was evaluated.
The frequency of SARS-CoV-2 infection (as determined by virus RNA detection) was evaluated in a group of 1,460 seropositive and a control group of 8,150 seronegative healthcare workers in three Centres of Northern Italy in the period June-November 2020. Neutralizing serum titers were analyzed in seropositive subjects with or without secondary SARS-CoV-2 infection.
During the 6-month survey, 1.78% seropositive subjects developed secondary SARS-CoV-2 infection while 6.63% seronegative controls developed primary infection (odds ratio: 0.26; 95% confidence interval: 0.17-0.38). Secondary infection was associated with low or absent serum neutralizing titer (p<0.01) and was mildly symptomatic in 45.8% cases vs 71.4% symptomatic primary infections (odds ratio: 0.34; 95% confidence interval: 0.16-0.78).
Immunity from natural infection appears protective from secondary infection; therefore, vaccination of seronegative subjects might be prioritized.
The rise of a new hypervirulent variant of
(hvKp) was recently reported, mainly linked to the ST23 lineage. The hvKp variants can cause severe infections, including hepatic abscesses, bacteremia, and ...meningitis, with a particularly disconcerting propensity to cause community-acquired, life-threatening infection among young and otherwise healthy individuals. The present study aimed to report the clinical characteristics of a hypermucoviscous
strain isolated in Italy and sustaining recurrent meningitis in a patient of Peruvian origin. A further objective was to retrospectively investigate, by means of whole-genome sequencing (WGS) analysis, the genomic features of such an isolate. The hypermucoviscosity phenotype of the strain (sk205y205t) was determined using the string test. Genomic information was obtained by WGS (Illumina) and bioinformatic analysis. Strain sk205y205t was susceptible to most antibiotics, despite the presence of some resistance genes, including
,
,
and
. The isolate belonged to ST65 and serotype K2, and exhibited several virulence factors related to the hvKp variant. Among these, were the siderophore genes
,
,
,
and
; the capsule-regulating genes
and
; and the type 1 and 3 fimbriae
and
, respectively. A further operon, encoding the genotoxin colibactin (
), was also identified. The virulence plasmids pK2044, pRJA166b, and pNDM. MAR were also detected. Phylogenetic investigation showed that this Italian strain is highly similar to a Chinese isolate, suggesting a hidden circulation of this hvKp ST65 K2 lineage.
Bloodstream infections (BSI) caused by multidrug-resistant (MDR) bacteria, pose a major threat for patients, especially for those who are immunosuppressed. Rapid pathogen detection and ...characterization from positive blood cultures are crucial in the management of patients with BSI to enable an adequate and timely antimicrobial therapy. This study aimed to investigate the potential role of the Molecular Mouse system, a new CE IVD molecular test designed to rapidly detect the causative agents of bacteremia and their resistance determinants, in the management of the therapy in critically ill patients. Agreement between the results of the Molecular Mouse and the conventional routine method was also considered. Overall, 100 positive blood cultures were collected from septic critically ill patients from May 2023 to January 2024 and analyzed with Molecular Mouse and routine protocols. The new instrument consistently agreed with the routine protocols in the case of monomicrobial blood cultures, while some discrepancies were obtained in the polymicrobial samples. Antimicrobial resistance genes were detected in 35 samples, with vanA and CTX-M-1/9 groups being the most frequently detected targets. Therapy was adjusted in 42 critically ill patients confirming the importance of new rapid molecular tests in the management of positive blood cultures, to adjust empirical therapy and use new antibiotics accurately.
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