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Combating antimicrobial resistance (AMR) requires comprehensive efforts, such as screening to identify patients colonized by multidrug-resistant microorganisms (MDROs). The primary purpose of this study was to estimate the AMR pattern of methicillin-resistant Staphylococcus aureus (MRSA) isolated from nasal surveillance swabs and MDROs isolated from pharyngeal and rectal surveillance swabs in patients attending a teaching hospital. Data were sought retrospectively, from 1 January 2017 to 31 December 2021, from the records produced by the hospital microbiology laboratory. Duplicate isolates, defined as additional isolates of the same microorganism with identical antibiograms, were excluded. Among Staphylococcus aureus isolates from nasal swabs, 18.2% were oxacillin-resistant. Among Gram-negative bacteria, 39.8% of Klebsiella pneumoniae and 83.5% of Acinetobacter baumannii isolates were carbapenem-resistant. Resistance to three antibiotic categories was high among Acinetobacter baumannii (85.8%) and Klebsiella pneumoniae (42.4%). The present data highlight a high prevalence of MDRO colonization among patients admitted to the hospital and suggest that screening for MDROs could be an important tool for infection control purposes, especially in geographical areas where limiting the spread of MDROs is crucial. The results also underline the importance of active surveillance, especially for carbapenem-resistant, Gram-negative bacteria in reducing their transmission, especially in high-risk units.

Ceftazidime-avibactam (CZA) is one of the best therapeutic options available for infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria. However, sporadic reports of CZA-resistant strains have been rapidly increasing in patients. Herein, we provide detailed case reports of the emergence of ceftazidime-avibactam resistance to identify their resistome and virulome using genomic molecular approaches. Sixteen isolates were collected from 13 patients at three hospitals in Catania and Catanzaro (Italy) between 2020-2021. Antimicrobial susceptibility was determined by broth microdiluition. The samples included in study were analyzed for resistome, virulome and Sequence Type (ST) using Whole Genome Sequencing (WGS). All strains were resistant to ceftazidime/avibactam, ciprofloxacin, extended-spectrum cephalosporins and aztreonam, 13/16 to meropenem, 8/16 to colistin and 7/16 to fosfomycin; 15/16 were susceptible to meropenem/vaborbactam; all strains were susceptible to cefiderocol. Molecular analysis showed circulation of three major clones: ST101, ST307 and ST512. In 10/16 strains, we found a blaKPC-3 gene; in 6/16 strains, four different blaKPC variants (blaKPC28-31-34-50) were detected. A plethora of other beta-lactam genes (blaSHV28-45-55-100-106-187-205-212, blaOXA1-9-48, blaTEM-181 and blaCTX-M-15) was observed; blaOXA-9 was found in ST307 and ST512, instead blaOXA48 in one out four ST101 strains. With regard to membrane permeability, ompK35 and ompK36 harbored frameshift mutations in 15/16 strains; analysis of ompK37 gene revealed that all strains harbored a non-functional protein and carry wild-type PBP3. There is an urgent need to characterize the mechanisms underlying carbapenem resistance and the intrinsic bacterial factors that facilitate the rapid emergence of resistance. Furthermore, it is becoming increasingly important to explore feasible methods for accurate detection of different KPC enzymes.

Orthopedic and trauma device-related infections (ODRI) due to high virulence microorganisms are a devastating complication after orthopedic surgery. Coagulase-negative Staphylococci (CoNS) are mainly involved but commensal bacteria, located in human mucous membranes, are emerging pathogens in ODRI. Currently, bacterial culture is the gold standard for ODRI but the diagnostic process remains time consuming and laborious. We evaluated a combination of microbiological approaches in the diagnosis of emerging pathogens involved in ODRI. We analyzed two synovial fluids, five tissue samples and five surgical wound swabs from two different patients with ODRI, attending the Department of Orthopedic and Trauma Surgery of Mater Domini Teaching Hospital, Catanzaro, Italy. Identification was carried out with a combination of microbiological approaches (culture, mass spectrometry and 16s rRNA gene sequencing). We demonstrated the importance of a combination of microbiological approaches for the diagnosis of emerging pathogens in ODRI, because the low number of cases in the literature makes it very difficult to formulate guidelines for the management of patients.

The COVID-19 pandemic may have had an effect on antimicrobial resistance. We compared the prevalence of ESKAPE multidrug-resistant (MDR) bacterial infections in COVID-19 affected/unaffected patients admitted to intensive care units (ICU) or infectious disease units at the “Mater Domini” University Hospital of Catanzaro between 1 March 2020 and 31 July 2021. Moreover, an analysis of MDR rates in ICU comparing the pre-pandemic period with the pandemic period was performed, and the possible consequence on in-hospital mortality was explored. One hundred and eighty-four ESKAPE isolates were analyzed from 362 SARS-CoV-2 positive and 199 negative patients. In total, 116 out of 171 Gram-negative isolates were classified as MDR, and a higher frequency was observed in COVID-19 compared with non-COVID-19 patients (74.2% vs. 60.3%; p = 0.052). A higher rate of MDR ESKAPE bacteria was observed in COVID-19 patients admitted to the ICU compared with COVID-19 unaffected patients admitted to the same ward in 2019 (88% vs. 80.4%; p = 0.186). Acinetobacter baumannii was the main pathogen in COVID-19 patients (58.7%), where it was the most frequent cause of bloodstream infection with the highest mortality rate (68.7%). Increase in MDR appeared to be associated with COVID-19 but only in the ICU setting. Acinetobacter baumannii was associated with the risk of death, indicating the importance of implementing infection control measures urgently.