Clinical Significance and Microbiological Characteristics of Staphylococcus lugdunensis in Cutaneous Infections.

Background/Objectives:Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CoNS) commonly found on human skin. Unlike other CoNS, S. lugdunensis has a notable potential to cause severe infections comparable to Staphylococcus aureus. This study aimed to characterize the clinical and microbiological profile of patients with S. lugdunensis skin infections at a single center. Methods: We conducted a retrospective analysis of patient records from the Dermatology Department of the University Hospital of Heraklion, Greece, covering the period from January 2014 to January 2024. Patients' clinical presentations, demographics, infection sites, comorbidities, prior infections, antimicrobial treatments, and therapeutic responses were examined. Specimens were collected, transported, and processed according to standardized microbiological protocols. Bacterial identification and antibiotic susceptibility testing were performed using the Vitek 2 automated system and MALDI-TOF MS, with results interpreted according to Clinical and Laboratory Standards Institute (CLSI) criteria. Results: A total of 123 skin specimens positive for S. lugdunensis were analyzed. The cohort comprised 62 males (50.4%) and 61 females (49.6%), with a mean age of 40.24 ± 20.14 years. Most specimens were collected from pus (84%), primarily from below the waist (66.7%). Hidradenitis suppurativa (26%) was the most common condition associated with S. lugdunensis, followed by folliculitis, abscesses, ulcers, cellulitis, and acne. Co-infections with other bacteria were noted in 49.6% of cases, and 25.2% of infections were nosocomially acquired. The majority of patients (65%) received systemic antibiotics, predominantly amoxicillin/clavulanic acid, cefuroxime axetil, and doxycycline, with a cure rate of 100%. All isolates were susceptible to several antibiotics, though resistance to penicillin (28.5%) and clindamycin (36%) was observed. Conclusions:S. lugdunensis is a significant pathogen in skin infections, capable of causing severe disease. The high cure rate demonstrates the effectiveness of appropriate antibiotic therapy. Continued monitoring and antimicrobial stewardship are essential to manage resistance and ensure effective treatment.

Antimicrobial Resistance Trends in Hidradenitis Suppurativa Lesions.

Background/Objectives: Antibiotic (AB) therapy is the first step in managing hidradenitis suppurativa (HS). Knowledge of the local patterns of antimicrobial resistance is paramount for the appropriate selection of antimicrobials. This study aimed to assess the occurrence of antibiotic resistance in patients with HS. Methods: A cross-sectional study was conducted on 103 patients with HS seen at the Dermatology Department at the University Hospital of Heraklion, Heraklion, Crete, Greece, from January 2019 to December 2023, who were not on any antibiotics in the last three months. Results: A total of 103 patients with HS participated in this study. Purulent material from 139 skin lesions of these patients was swabbed, and 79.86% (111/139) tested positive for bacteria. Gram-positive isolates accounted for 73%, whereas Gram-negative isolates comprised 27%. Among the isolates, 85.1% were aerobes, and 14.9% were anaerobic. The most common bacterial families isolated were Staphylococcaceae (48.27%), Enterobacteriaceae (14.94%), and Streptococcaceae (6.89%). The antibiogram profiles of bacterial cultures revealed a 57.1% resistance to levofloxacin and a 53.3% resistance to penicillin in Staphylococcus lugdunensis, whereas Staphylococcus aureus showed a 76.9% resistance to penicillin and a 58.3% resistance to fusidic acid. High resistance rates of 63.5% for tigecycline, 63.3% for ampicillin, and 40.5% for colistin were observed for Gram-negative isolates. Resistances of 62.5%, 61.5%, and 53.8% to erythromycin, clindamycin, and penicillin, respectively, were observed in the anaerobes. Conclusions: Patients with HS displayed considerable resistance to bacterial proliferation. The revised therapeutic guidelines for HS should incorporate the latest insights into bacterial antibiotic resistance.

A Comparative Analysis of MRSA: Epidemiology and Antibiotic Resistance in Greece and Romania.

This study provides a comparative analysis of 243 Methicillin-resistant Staphylococcus aureus (MRSA) isolated strains from Greece and Romania, focusing on their epidemiology and antibiotic resistance patterns. Laboratory procedures included phenotypic and automated identification methods, susceptibility testing, DNA isolation, and PCR for detecting antibiotic resistance genes (MecA, SCCmec). Our study results show significant regional differences. In both regions, males have higher MRSA infection rates than females, but the percentages vary. Greece has a higher incidence of MRSA in younger age groups compared to Romania. The majority of MRSA infections occur in inpatient settings in both countries, highlighting the necessity for enhanced infection control measures. Antibiotic resistance profiles reveal higher resistance to several antibiotics in Greece compared to Romania. A molecular analysis shows a widespread distribution of antibiotic resistance genes among MRSA isolates in Greece. These results highlight the necessity for accomplished preventive strategies and optimized treatment protocols.

Central Line-Associated Bloodstream Infection Due to Elizabethkingia anophelis: Case Report and Literature Review on Pediatric Infections.

Elizabethkingia anophelis is an opportunistic pathogen causing lifethreatening infections in humans, particularly in immunocompromised patients, neonates and the elderly. We report a case of central line-associated bloodstream infection by E. anophelis in a 2.5-year-old girl with acute lymphoblastic leukemia successfully treated with a combination of piperacillin/tazobactam and amikacin. The literature was also reviewed on pediatric infections caused by E. anophelis, focusing on clinical manifestations, underlying medical conditions, treatment and outcome. Accurate identification with MALDI-TOF, or using molecular techniques, is of the utmost importance because treatment and prognosis differ depending on the species. Considering that E. anophelis is multiresistant to antibiotics and that inappropriate antimicrobial therapy is an independent risk factor for mortality, the early, accurate identification of bacterial species and prompt effective treatment are essential to achieve optimal therapeutic outcomes.

Antimicrobial resistance trends among Klebsiella pneumoniae associated with urinary tract infections in Crete, Greece, 2017-2022.

Klebsiella pneumoniae is one of the most prevalent bacteria causing urinary tract infections (UTIs). Its increasing resistance to a wide array of antibiotics limits available treatment options. This study investigated the characteristics and trends of antimicrobial resistance in K. pneumoniae isolated from UTIs in Crete, Greece, during 2017 and 2022. Among the 11,946 Enterobacteriaceae isolated from urine specimens, a total of 1,771 K. pneumoniae isolates were identified (14.8%), with an isolation frequency secondary to Escherichia coli (66.3%). K. pneumoniae isolates increased over the years, with a peak in the year 2022. Higher resistance rates were detected in ciprofloxacin (41%), trimethoprim/sulfamethoxazole (TMP/SMX) (38.1%) and nitrofurantoin (33.9%). Resistance to ciprofloxacin, amoxicillin/clavulanic acid, tigecycline, and TMP/SMX significantly increased from 33.7%, 24%, 6%, and 33.1%, respectively, over the years 2017-2019, to 47.8%, 34.2%, 14.3% and 42.8%, respectively, over the period 2020-2022. ESBL production and carbapenem resistance were decreased by 2.2% and 3.7%, respectively, over the two three-year periods (2017-2019 and 2020-2022). Among the 278 carbapenem-resistant K. pneumoniae (CRKP) isolates, 164 (59%), 66 (23.7%), 18 (6.5%) and 16 (5.8%) were positive for KPC, NDM, VIM and OXA-48 enzymes, respectively. Only 14 (5%) isolates harboured two carbapenemase genes, namely 10 (3.6%) both blaNDM and blaVIM, and 4 (1.4%) both blaKPC and blaNDM. Females, inpatients and the elderly were more frequently affected by CRKP. The frequency of multidrug-resistant (MDR) and extensively drug-resistant (XDR) isolates were 32.6% and 7.7%, respectively. Continuous surveillance of local microbial prevalence and monitoring of antimicrobial resistance patterns provide critical information to guide the empiric therapy for UTIs and control the spread of MDR bacteria.

In Vitro Activity of Dalbavancin and Fourteen Other Antimicrobial Agents Against Toxigenic Clostridioides Difficile Clinical Isolates in a Greek Tertiary-Care Hospital.

OBJECTIVE: Clostridioides difficile is a major cause of healthcare-associated diarrhea worldwide. For years, metronidazole and vancomycin were considered the standard treatment for C. difficile infection (CDI). However, they are increasingly being associated with treatment failure and recurrence. In this study we investigated the in vitro activity of dalbavancin and fourteen other antimicrobials against 155 toxigenic C. difficile isolates originating from patients with C. difficile-associated diarrhea. MATERIALS AND METHODS: Antimicrobial susceptibility was evaluated by the MIC Test Strip and the results were interpreted using both the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial susceptibility Testing (EUCAST) breakpoints. RESULTS: C. difficile isolates were fully susceptible to metronidazole, vancomycin, amoxicillin/ clavulanate, piperacillin/tazobactam, and tigecycline. All isolates were dalbavancin susceptible by the CLSI breakpoint (≤ 0.25 µg/ml) compared with 97.4% susceptibility by the EUCAST breakpoint (≤ 0.125 µg/ml). Dalbavancin demonstrated significantly lower MIC50 and MIC90 values compared to vancomycin (0.047 vs. 0.38 and 0.125 vs. 0.5, respectively, p < 0.001). Resistance rates to penicillin, ampicilin, cefoxitin, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, and tetracycline were 20%, 14.2% , 100%, 75.5%, 0.6%, 51%, 36.1%, 3.2%, and 14.8%, respectively. Multidrug-resistant (MDR) phenotypes were detected among 41.3% of the isolates. CONCLUSION: Dalbavancin exhibited potent activity against the isolates tested. As C. difficile is an important healthcare-associated pathogen, continued surveillance is required to monitor for development of resistance.

Prevalence and antimicrobial resistance of bacterial enteropathogens in Crete, Greece, during 2011-2022.

Diarrheal diseases are of great concern worldwide and are responsible for considerable morbidity and mortality. This study investigated the epidemiology and the antibiotic susceptibility of bacterial enteropathogens among diarrheal patients of all ages in Crete, Greece during 2011-2022. Stool specimens were tested by conventional cultural methods for Salmonella, Shigella, Campylobacter, diarrheagenic Escherichia coli (EPEC, STEC), Yersinia enterocolitica, Aeromonas species and Clostridioides difficile. Antimicrobial susceptibility was determined by the disk diffusion method for Enterobacterales, Campylobacter and Aeromonas, and by the gradient diffusion method for C. difficile. Of the 26,060 stool samples from patients of any age, 1,022 (3.9%) were positive for bacterial enteropathogens. Campylobacter spp. were the most commonly isolated bacteria (56.4%), followed by Salmonella enterica (32.3%), and E. coli (EPEC, STEC) (6.5%). Toxigenic C. difficile was isolated from 341 out of 8,848 diarrheal specimens examined (3.9%). Resistance to ampicillin was observed in 12.4% of Salmonella, 66.7% of Shigella and 34.8% of E. coli (EPEC, STEC) isolates. Resistance to trimethoprim/sulfamethoxazole was observed in 5.8% of Salmonella, 33.3% of Shigella, and 15.1% of E. coli (EPEC, STEC) isolates. High rates of ciprofloxacin resistance (77.3%) were detected among Campylobacter isolates, while resistance to erythromycin was observed in 2.4% of them. All C. difficile isolates were susceptible to vancomycin and metronidazole. Our findings suggest declining trends in prevalence of bacterial enteropathogens, except for Campylobacter spp. and changes in the susceptibility rates to antimicrobials. Continuous surveillance of prevalence and antimicrobial susceptibility of bacterial enteropathogens is mandatory for implementing targeted and effective prevention and infection control measures.

Antimicrobial Resistance of Streptococcus pneumoniae Clinical Serotypes between 2017 and 2022 in Crete, Greece.

BACKGROUND: Pneumococcal disease is still considered a global problem. With the introduction of pneumococcal conjugate vaccines (PCVs) serotype epidemiology changed, but antimicrobial resistance persists constituting a serious problem. The current study aimed to determine the serotype distribution and the antimicrobial susceptibility of recent Streptococcus pneumoniae isolates, following implementation of the 13-valent conjugate vaccine (PCV13). MATERIALS AND METHODS: From January 2017 to December 2022 we evaluated 116 nonduplicate S. pneumoniae isolates collected from adult patients (21 - 98 years) cared for in the University Hospital of Heraklion, Crete, Greece. Pneumococcal isolates were serotyped by the Quellung reaction, and antimicrobial susceptibility testing was performed using E-test. Multidrug resistance (MDR) was defined as non-susceptibility to at least one agent in ≥3 classes of antibiotics. RESULTS: Among the 116 isolates, 31% were recognized as invasive pneumococcal strains, while 69% were non-invasive. The isolates tested belonged to 25 different serotypes. The most prevalent serotypes were 11A (10.3%), and 35B (10.3%), followed by 3 (9.5%), 15A (7.8%), 25F (6.9%), 19A (5.3%), 35F (5.3%), and others (44.6%). The coverage rates of PCV13 and the pneumococcal polysaccharide vaccine (PPSV23) were 26.7% and 57.8%, respectively. PCV13 and PPSV23 serotypes decreased between 2017 - 2019 and 2020 - 2022, with a parallel increase in the non-vaccine types. Resistance rates to erythromycin, clindamycin, trimethoprim/sulfamethoxazole, penicillin, levofloxacin, and ceftriaxone, were 40.5%, 21.6%, 13.8%, 12.1%, 3.4%, and 0%, respectively. All isolates were susceptible to vancomycin, linezolid, and daptomycin. MDR was observed among 36 (31%) S. pneumoniae isolates. CONCLUSION: The increasing levels of resistance in S. pneumoniae in Crete, Greece, highlight the need for continuous surveillance of antimicrobial resistance and development of strategies for its reduction, including antimicrobial stewardship programs, increased pneumococcal vaccination, and development of next generation PCVs with a wider serotype coverage.

Enterobacterales carrying chromosomal AmpC ß-lactamases in Europe (EuESCPM): Epidemiology and antimicrobial resistance burden from a cohort of 27 hospitals, 2020-2022.

INTRODUCTION: The ESCPM group (Enterobacter species including Klebsiella aerogenes - formerly Enterobacter aerogenes, Serratia species, Citrobacter freundii complex, Providencia species and Morganella morganii) has not yet been incorporated into systematic surveillance programs. METHODS: We conducted a multicentre retrospective observational study analysing all ESCPM strains isolated from blood cultures in 27 European hospitals over a 3-year period (2020-2022). Diagnostic approach, epidemiology, and antimicrobial susceptibility were investigated. RESULTS: Our study comprised 6,774 ESCPM isolates. MALDI-TOF coupled to mass spectrometry was the predominant technique for bacterial identification. Susceptibility to new ß-lactam/ß-lactamase inhibitor combinations and confirmation of AmpC overproduction were routinely tested in 33.3% and 29.6% of the centres, respectively. The most prevalent species were E. cloacae complex (44.8%) and S. marcescens (22.7%). Overall, third-generation cephalosporins (3GC), combined third- and fourth-generation cephalosporins (3GC + 4GC) and carbapenems resistance phenotypes were observed in 15.7%, 4.6%, and 9.5% of the isolates, respectively. AmpC overproduction was the most prevalent resistance mechanism detected (15.8%). Among carbapenemase-producers, carbapenemase type was provided in 44.4% of the isolates, VIM- (22.9%) and OXA-48-enzyme (16%) being the most frequently detected. E. cloacae complex, K. aerogenes and Providencia species exhibited the most notable cumulative antimicrobial resistance profiles, with the former displaying 3GC, combined 3GC + 4GC and carbapenems resistance phenotypes in 15.2%, 7.4%, and 12.8% of the isolates, respectively. K. aerogenes showed the highest rate of both 3GC resistant phenotype (29.8%) and AmpC overproduction (32.1%), while Providencia species those of both carbapenems resistance phenotype (42.7%) and carbapenemase production (29.4%). ESCPM isolates exhibiting both 3GC and combined 3GC + 4GC resistance phenotypes displayed high susceptibility to ceftazidime/avibactam (98.2% and 95.7%, respectively) and colistin (90.3% and 90.7%, respectively). Colistin emerged as the most active drug against ESCPM species (except those intrinsically resistant) displaying both carbapenems resistance phenotype (85.8%) and carbapenemase production (97.8%). CONCLUSIONS: This study presented a current analysis of ESCPM species epidemiology in Europe, providing insights to inform current antibiotic treatments and guide strategies for antimicrobial stewardship and diagnostics.

Clinical and microbiological characteristics of nocardiosis: A 5-year single-center study in Crete, Greece.

Nocardiosis is a rare disease affecting both immunocompromised and immunocompetent hosts, presented in various clinical forms ranging from localized to disseminated infection. Aim of the present study was to investigate the clinical and microbiological characteristics of nocardiosis, antimicrobial resistance profiles, treatment, and outcomes of Nocardia infection over the last 5 years at our institution. The medical records and microbiological data of patients affected by nocardiosis and treated at the university hospital of Heraklion, Crete, Greece, between 2018 and 2022, were retrospectively analyzed. The isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and through sequencing of 16S rRNA. Antimicrobial susceptibility for 17 agents was determined by E-test and results were interpreted according to CLSI guidelines. Among the 28 Nocardia isolates, eight species were identified, with Nocardia brasiliensis being the most prevalent (32.1%), followed by Nocardia otitidiscaviarum (25%), and Nocardia farcinica (14.3%). Skin and soft tissue infections were the most common presentations, noted in 13 (50%) patients, followed by pulmonary infection presented in 10 (38.5%) patients. Fifteen patients (57.7%) had at least one underlying disease, and 11 (42.3%) were on immunosuppressive or long-term corticosteroid treatment. Susceptibility rates of linezolid, tigecycline, amikacin, trimethoprim-sulfamethoxazole, moxifloxacin, and imipenem were 100, 100, 96.4, 92.9, 82.1, and 42.9%, respectively. The 26 patients in this study were treated with various antibiotics. Mortality rate was 3.8%, and the patient who died had disseminated infection. Since epidemiology and antimicrobial susceptibility are evolving, continuous surveillance is mandatory in order to initiate appropriate treatment in a timely manner.

In Vitro Activities of Ceftobiprole, Dalbavancin, Tedizolid and Comparators against Clinical Isolates of Methicillin-Resistant Staphylococcus aureus Associated with Skin and Soft Tissue Infections.

Skin and soft tissue infections (SSTIs) are associated with significant morbidity and healthcare costs, especially when caused by methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin is a preferred antimicrobial therapy for the management of complicated SSTIs (cSSTIs) caused by MRSA, with linezolid and daptomycin regarded as alternative therapeutic options. Due to the increased rates of antimicrobial resistance in MRSA, several new antibiotics with activity against MRSA have been recently introduced in clinical practice, including ceftobiprole, dalbavancin, and tedizolid. We evaluated the in vitro activities of the aforementioned antibiotics against 124 clinical isolates of MRSA obtained from consecutive patients with SSTIs during the study period (2020-2022). Minimum inhibitory concentrations (MICs) for vancomycin, daptomycin, ceftobiprole, dalbavancin, linezolid and tedizolid were evaluated by the MIC Test Strip using Liofilchem strips. We found that when compared to the in vitro activity of vancomycin (MIC90 = 2 µg/mL), dalbavancin possessed the lowest MIC90 (MIC90 = 0.094 µg/mL), followed by tedizolid (MIC90 = 0.38 µg/mL), linezolid, ceftobiprole, and daptomycin (MIC90 = 1 µg/mL). Dalbavancin demonstrated significantly lower MIC50 and MIC90 values compared to vancomycin (0.064 vs. 1 and 0.094 vs. 2, respectively). Tedizolid exhibited an almost threefold greater level of in vitro activity than linezolid, and also had superior in vitro activity compared to ceftobiprole, daptomycin and vancomycin. Multidrug-resistant (MDR) phenotypes were detected among 71.8% of the isolates. In conclusion, ceftobiprole, dalbavancin and tedizolid exhibited potent activity against MRSA and are promising antimicrobials in the management of SSTIs caused by MRSA.

In vitro activities of omadacycline, eravacycline, cefiderocol, apramycin, and comparator antibiotics against Acinetobacter baumannii causing bloodstream infections in Greece, 2020-2021: a multicenter study.

Resistance of Acinetobacter baumannii to multiple clinically important antimicrobials has increased to very high rates in Greece, rendering most of them obsolete. The aim of this study was to determine the molecular epidemiology and susceptibilities of A. baumannii isolates collected from different hospitals across Greece. Single-patient A. baumannii strains isolated from blood cultures (n = 271), from 19 hospitals, in a 6-month period (November 2020-April 2021) were subjected to minimum inhibitory concentration determination and molecular testing for carbapenemase, 16S rRNA methyltransferase and mcr gene detection and epidemiological evaluation. 98.9% of all isolates produced carbapenemase OXA-23. The vast majority (91.8%) of OXA-23 producers harbored the armA and were assigned mainly (94.3%) to sequence group G1, corresponding to IC II. Apramycin (EBL-1003) was the most active agent inhibiting 100% of the isolates at ≤16 mg/L, followed by cefiderocol which was active against at least 86% of them. Minocycline, colistin and ampicillin-sulbactam exhibited only sparse activity (S <19%), while eravacycline was 8- and 2-fold more active than minocycline and tigecycline respectively, by comparison of their MIC50/90 values. OXA-23-ArmA producing A. baumannii of international clone II appears to be the prevailing epidemiological type of this organism in Greece. Cefiderocol could provide a useful alternative for difficult to treat Gram-negative infections, while apramycin (EBL-1003), the structurally unique aminoglycoside currently in clinical development, may represent a highly promising agent against multi-drug resistant A. baumanni infections, due to its high susceptibility rates and low toxicity.

Examining the Prevalence and Antibiotic Susceptibility of S. aureus Strains in Hospitals: An Analysis of the pvl Gene and Its Co-Occurrence with Other Virulence Factors.

S. aureus is a pathogenic bacterium that causesinfections. Its virulence is due to surface components, proteins, virulence genes, SCCmec, pvl, agr, and SEs, which are low molecular weight superantigens. SEs are usually encoded by mobile genetic elements, and horizontal gene transfer accounts for their widespread presence in S. aureus. This study analyzed the prevalence of MRSA and MSSA strains of S. aureus in two hospitals in Greece between 2020-2022 and their susceptibility to antibiotics. Specimens collected were tested using the VITEK 2 system and the PCR technique to detect SCCmec types, agr types, pvl genes, and sem and seg genes. Antibiotics from various classes were also tested. This study examined the prevalence and resistance of S. aureus strains in hospitals. It found a high prevalence of MRSA and that the MRSA strains were more resistant to antibiotics. The study also identified the genotypes of the S. aureus isolates and the associated antibiotic resistances. This highlights the need for continued surveillance and effective strategies to combat the spread of MRSA in hospitals. This study examined the prevalence of the pvl gene and its co-occurrence with other genes in S. aureus strains, as well as their antibiotic susceptibility. The results showed that 19.15% of the isolates were pvl-positive and 80.85% were pvl-negative. The pvl gene co-existed with other genes, such as the agr and enterotoxin genes. The results could inform treatment strategies for S. aureus infections.

In vitro activity of newer ß-lactam/ß-lactamase inhibitor combinations, cefiderocol, plazomicin and comparators against carbapenemase-producing Klebsiella pneumoniae isolates.

Infections by carbapenem-resistant Klebsiella pneumoniae (CRKP) remain one of the greatest healthcare threats associated with significant morbidity and mortality. New antimicrobials were recently developed to address this threat. We assessed the epidemiology of carbapenemase-producing K. pneumoniae (CPKP) isolates recovered in a Greek university hospital during 2021, and their susceptibilities to old and newer antimicrobials. Minimum inhibitory concentrations (MICs) were determined by the MIC Test Strip method, except for cefiderocol (CFDC) and colistin that were evaluated by the broth microdilution method. A total of 110 CPKP strains were isolated, with KPC-producers being the most prevalent (64.6%). Among the agents tested, plazomicin (PL) displayed the highest activity against all the isolates (MIC50/MIC90, 0.5/1.5 µg/ml), followed by tigecycline (MIC50/MIC90, 1.5/4 µg/ml). All KPC-producing K. pneumoniae were susceptible to ceftazidime-avibactam (CAZ/AVI) and meropenem-vaborbactam (M/V) and 97.2% of them to imipenem-relebactam (I/R). Among the MBL-producing isolates, PL and CFDC exhibited the highest activity.

Nocardia elegans primary iliopsoas abscess: A case report and literature review.

Nocardia species are rare causative agents of psoas abscess, more frequently occurring as part of disseminated infection. Only sporadic cases have been reported so far, with Nocardia asteroides and Nocardia farcinica being the most common causative agents. Nocardia elegans is an opportunistic pathogen, accounting for only 0.3-0.6% of infections caused by Nocardia species, usually affecting the respiratory tract.In this study, a previously healthy 74-year-old man was admitted to the University Hospital of Heraklion with fever and intense pain radiating from the lumbar region to the groin and the left thigh, increasing with movement. Imaging findings revealed a large abscess in the left iliopsoas. Blood and pus aspirate cultures yielded a pure culture of Nocardia that was identified by 16S rRNA sequence as N. elegans. The patient was successfully treated with drainage of the abscess along with administration of ceftriaxone, linezolid and trimethoprim-sulfamethoxazole. To our knowledge, this is the first report of iliopsoas abscess caused by N. elegans. Early, accurate diagnosis and timely treatment with drainage of the abscess and long-term administration of antimicrobial agents optimize the outcome.

A 60-Year Literature Review on Hepatic Actinomycosis.

Hepatic actinomycosis (HA) is a rare infection with an indolent course, atypical clinical manifestations, nonspecific laboratory and imaging findings, and challenging diagnosis. We describe a case of a 35-year-old female who developed HA 2 weeks after gastrectomy. In addition, we analyzed clinical characteristics and outcome of 157 additional cases of HA identified in a 60-year literature review. Patients with HA were predominantly male (57%) and more than one-half were between 40 and 70 years of age. The infection was cryptogenic in 80.8% of cases. Risk factors for HA were identified in 63.1% of the patients. Clinical presentation included fever (57.7%), abdominal pain (52.1%), weight loss (45.1%), anorexia (27.5%), fatigue and chills (12.7% each), and malaise (12%) over a 2.35 ± 3.5 months period. Leukocytosis, elevated alkaline phosphatase, erythrocyte sedimentation rate, and C-reactive protein were the most frequent laboratory findings. Radiologic imaging revealed that the right lobe was more frequently affected (62.5%) with a single lesion found in two-thirds of cases. Diagnosis was achieved by histopathologic examination in 70.6% of cases. Cultures yielded Actinomyces in 45 instances, with A. israelii being the most frequent species. Less than one-half of the patients were treated only with antibiotics, while the others received combined medical and surgical treatment. The median duration of antibiotic therapy was 135 days. The presence of multiple lesions or solid tumor-like lesions (without liquefaction) was significantly associated with medical therapy alone. The outcome was favorable in most cases (94%). Although rarely encountered, HA should be considered in patients with a chronic or subacute inflammatory process of the liver to promptly diagnose and treat.

Epidemiology and in vitro activity of ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, eravacycline, plazomicin, and comparators against Greek carbapenemase-producing Klebsiella pneumoniae isolates.

BACKGROUND: The increase in carbapenem-resistant Klebsiella pneumoniae (CRKP) infections is of great concern because of limited treatment options. New antimicrobials were recently approved for clinical therapy. This study evaluated the epidemiology of carbapenemase-producing K. pneumoniae isolates collected at a Greek university hospital during 2017-2020, and their susceptibilities to ceftazidime-avibactam (CAZ/AVI), meropenem-vaborbactam (M/V), imipenem-relebactam (I/R), eravacycline, plazomicin, and comparators. METHODS: Minimum inhibitory concentrations (MICs) were evaluated by Etest. Only colistin MICs were determined by the broth microdilution method. Carbapenemase genes were detected by PCR. Selected isolates were typed by multilocus sequence typing (MLST). RESULTS: A total of 266 carbapenemase-producing K. pneumoniae strains were isolated during the 4-year study period. Among them, KPC was the most prevalent (75.6%), followed by NDM (11.7%), VIM (5.6%), and OXA-48 (4.1%). KPC-producing isolates belonged mainly to ST258 and NDM producers belonged to ST11, whereas OXA-48- and VIM producers were polyclonal. Susceptibility to tigecycline, fosfomycin, and colistin was 80.5%, 83.8%, and 65.8%, respectively. Of the novel agents tested, plazomicin was the most active inhibiting 94% of the isolates at ≤ 1.5 µg/ml. CAZ/AVI and M/V inhibited all KPC producers and I/R 98.5% of them. All OXA-48 producers were susceptible to CAZ/AVI and plazomicin. The novel ß-lactam/ß-lactamase inhibitors (BLBLIs) tested were inactive against MBL-positive isolates, while eravacycline inhibited 61.3% and 66.7% of the NDM and VIM producers, respectively. CONCLUSIONS: KPC remains the predominant carbapenemase among K. pneumoniae, followed by NDM. Novel BLBLIs, eravacycline, and plazomicin are promising agents for combating infections by carbapenemase-producing K. pneumoniae. However, the emergence of resistance to these agents highlights the need for continuous surveillance and application of enhanced antimicrobial stewardship.

Ceftazidime-avibactam, meropenen-vaborbactam, and imipenem-relebactam in combination with aztreonam against multidrug-resistant, metallo-ß-lactamase-producing Klebsiella pneumoniae.

The spread of multidrug-resistant (MDR), metallo-ß-lactamase (MBL)-producing Klebsiella pneumoniae represents a major therapeutic challenge. The newly introduced ß-lactam-ß-lactamase inhibitors (BLBLIs), ceftazidime/avibactam (CAZ/AVI), meropenem/vaborbactam (M/V), and imipenem/relebactam (I/R) are inactive against MBLs. The aim of this study was to evaluate the in vitro efficacy of aztreonam (ATM) in combination with CAZ/AVI, M/V, and I/R against 40 MDR, MBL-producing, and serine-ß-lactamases co-producing Klebsiella pneumoniae using the Etest method. Synergy was defined as a fractional inhibitory concentration index ≤0.5. All isolates were resistant to ATM, CAZ/AVI, and I/R and 38/40 (95%) were resistant to M/V. Synergy was observed in 97.5% in the combinations CAZ/AVI-ATM, and I/R-ATM and in 72.5% in the combination M/V-ATM. Further clinical studies are required to confirm the efficacy of these antimicrobial combinations.

Antimicrobial susceptibility patterns of clinically significant Gram-positive anaerobic bacteria in a Greek tertiary-care hospital, 2017-2019.

Antimicrobial resistance among anaerobic bacteria is increasingly recognized with geographic differences. In this study we analyzed the distribution and antimicrobial susceptibility profiles of 358 Gram-positive clinically significant anaerobes, isolated from 2017 to 2019, in a Greek tertiary-care hospital. The species identification was performed by Vitek 2 and conventional biochemical methods, and the antimicrobial susceptibility testing by the E-test method. The antimicrobial agents tested were penicillin, ampicillin, amoxicillin-clavulanic acid, piperacillin-tazobactam, cefoxitin, imipenem, meropenem, clindamycin, metronidazole, moxifloxacin, chloramphenicol, tigecycline and vancomycin. Clostridioides difficile isolates were also tested against tetracycline. The results were interpreted using the CLSI and the EUCAST breakpoints. Clostridium species accounted for 35.5% of the isolates, followed by Gram-positive cocci (GPAC) (33.2%) and non-spore-forming bacilli (31.3%). Beta-lactams, ß-lactam/ß-lactamase inhibitors, cefoxitin, carbapenems, chloramphenicol, tigecycline and vancomycin proved all effective against the GPAC tested. Clindamycin, moxifloxacin and metronidazole resistance varied among different species of GPAC. Clindamycin and moxifloxacin resistance observed was 10% and 5% for Cutibacterium acnes, 25% and 6.2% for Actinomyces odontolyticus and 40% and 5% for Clostridium perfringens. C. difficile isolates were fully susceptible to metronidazole, vancomycin, and tigecycline. Resistance rates to clindamycin, moxifloxacin and tetracycline were 62.9%, 30% and 24.3%, respectively. These data highlight the need for periodic surveillance to monitor changes in susceptibility profiles.