Effect of Low-Level Laser Irradiation (810 nm) on the Proliferation and Differentiation of Osteoblast-Like Cells Cultured on SLA Titanium Discs Exposed to a Peri-implantitis Environment

Introduction: Elimination of inflammation and re-osseointegration are the major objectives of peri-implantitis therapy. Existing data, however, do not support any decontamination approach. Thus, the present in vitro study aims to assess whether the air-debriding decontamination method with erythritol powder restores the biocompatibility of infected titanium discs and to investigate the potent biomodulatory ability of diode laser (810 nm) irradiation to promote cell proliferation and differentiation of premature osteoblast-like cells (MG63) towards osteocytes. Methods: The experimental groups consisted of cells seeded on titanium discs exposed or not in a peri-implantitis environment with or without biomodulation. Infected discs were cleaned with airflow with erythritol powder. Cell cultures seeded on tricalcium phosphate (TCP) surfaces with or without biomodulation with a laser (810 nm) were used as controls. The study evaluated cell viability, proliferation, adhesion (SEM) at 24, 48 and 72 hours, and surface roughness changes (profilometry), as well as the effects of low-level laser therapy (LLLT) on ALP, OSC, TGF-b1, Runx2, and BMP-7 expression in MG63 cells' genetic profile on days 7, 14, and 21. Results: The MTT assay as well as the FDA/PI method revealed that cell proliferation did not show significant differences between sterile and decontaminated discs at any timepoint. SEM photographs on day 7 showed that osteoblast-like cells adhered to both sterile and disinfected surfaces, while surface roughness did not change based on amplitude parameters. The combination of airflow and LLLT revealed a biomodulated effect on the differentiation of osteoblast-like cells with regard to the impact of laser irradiation on the genetic profile of the MG63 cells. Conclusion: In all groups tested, osteoblast-like cells were able to colonize, proliferate, and differentiate, suggesting a restoration of biocompatibility of infected discs using airflow. Furthermore, photomodulation may promote the differentiation of osteoblast-like cells cultured on both sterile and disinfected titanium surfaces.

Detection of Virulence-Associated Genes among Brucella melitensis and Brucella abortus Clinical Isolates in Greece, 2001-2022

Brucellosis remains an important zoonotic disease in several parts of the world; in Greece, although it is declining, it is still endemic, affecting both the financial and public health sectors. The current study was undertaken to investigate the presence and distribution of virulence-associated genes among Brucella spp. clinical strains isolated during 2001-2022. Species identification was performed using conventional methodology and Bruce-ladder PCR. The presence of the virulence genes mviN, manA, wbkA, perA, omp19, ure, cbg and virB was investigated using PCR. During the study period, a total of 334 Brucella isolates were identified, of which 328 (98.2%) were detected from positive blood cultures; 315 (94.3%) of the isolates were identified as B. melitensis, whilst the remaining 16 (4.8%) and 3 (0.9%) were identified as B. abortus and B. suis, respectively. Notably, two of the B. melitensis were assigned to the REV-1 vaccine strain type. The presence of the omp19, manA, mviN and perA genes was confirmed in all 315 B. melitensis isolates, while ure, wbkA, cbg and virB genes were detected in all but 9, 2, 1 and 1 of the isolates, respectively. All eight virulence genes were amplified in all B. abortus and B. suis isolates. The detection rate of virulence genes did not differ significantly among species. In conclusion, brucellosis is still considered a prevailing zoonotic disease in Greece, with the majority of the isolates identified as B. melitensis. The eight pathogenicity-associated genes were present in almost all Brucella isolates, although the ure gene was absent from a limited number of B. melitensis isolates.

Implantable Cardiac Defibrillator-Related Culture-Negative Infection: A Case of Coxiella burnetii Infection

Coxiella burnetii is one of the most common causes of blood culture-negative infective endocarditis (IE). However, only a few cases of cardiac implantable electronic devices (CIED) infection have been reported in the literature. Herein, we present a case of CIED-related blood culture-negative infection attributed to C. burnetii. A 54-year-old male was admitted to our hospital due to prolonged fatigue, a low-grade fever lasting more than a month, and weight loss. Three years ago, he received an implantable cardiac defibrillator (ICD) as a primary prevention measure against sudden cardiac death. An initial transthoracic and transesophageal echocardiography showed a dilated left ventricle with severely impaired systolic function, while the ventricular pacing wire was inside the right ventricle with a large echogenic mass (2.2 × 2.5 cm) adherent to it. Repeated blood cultures were negative. The patient underwent transvenous lead extraction. A transesophageal echocardiography after the extraction revealed multiple vegetations on the tricuspid valve with moderate to severe valve regurgitation. A surgical replacement of the tricuspid valve was determined after a multidisciplinary heart team approach. Serology tests showed increased IgG antibodies in phase I (1:16,394) and phase II (1:8192), and a definite diagnosis of CIED infection was made based on the serological tests.

The Importance of Complementary PCR Analysis in Addition to Serological Testing for the Detection of Transmission Sources of Brucella spp. in Greek Ruminants

The early and accurate diagnosis of brucellosis, a ubiquitous zoonotic infection, is significant in preventing disease transmission. This study aimed to assess the infection rate of Brucella spp. in ruminants and to evaluate the agreement between a serological test and a molecular method for the detection of infected cases. Blood and milk samples of 136 ruminants were analyzed using two laboratory methods: the Rose Bengal plate (RBP) test to detect B. abortus and B. melitensis antibodies and the molecular polymerase chain reaction (PCR) method for the presence of bacterial DNA. The agreement between the methods was assessed using the kappa statistic. Based on the RBP test, there were 12 (8.8%) seropositive animals (10 sheep and 2 cows), while 2 (1.4%) samples were positive on PCR analysis. The positive PCR samples were from seronegative cow samples on RBP testing. There was slight agreement (k = −0.02) between the two methods, which was not statistically significant. Our results indicate that complementary molecular methods are useful to detect the bacteria in infected animals that are seronegative due to an early stage of infection. Therefore, a combination of molecular methods and serological tests can be applied to detect brucellosis in ruminants efficiently.

Molecular detection of Rickettsia felis in common fleas in Greece and comparative evaluation of genotypic methods

INTRODUCTION

Rickettsia felis is the causative agent of flea-borne spotted fever (FBSF), an emerging zoonosis. Although there is evidence of FBSF in Greece, fleas, the classic vectors of R. felis, have not been adequately studied. Thus, the aim of this study was to detect and characterize bacteria of genus Rickettsia and especially R. felis from common fleas parasitizing domestic cats and dogs in Greece and evaluate the efficiency of established molecular techniques.

MATERIALS AND METHODS

DNA of flea-pools (samples) by animal-host was investigated by quantitative real-time PCRs (qPCR), and 16S metagenomics (16S). Determination of Rickettsia spp., Rickettsia felis-like organisms (RFLOs), and R. felis was based on a combination of qPCRs targeting gltA and ompB genes, 16S automated metagenomics and manual comparison of 16S sequences for >99% similarity with the publicly available 16S R. felis GenBank sequences using the Basic Local Alignment Search Tool (BLAST_>99). Information for the animal-hosts was available and statistically analyzed.

RESULTS

Among 100 flea-pools, R. felis was detected in 14 samples with a combination of six, five and three assays in 10, two and two samples, respectively. The sensitivity of the assays for Rickettsia genus (16S, and genus specific qPCRs) ranged from 62.5% to 93.8% and the specificity from 65.0% to 100%. R. felis-targeting qPCRs for gltA and ompB demonstrated sensitivity and specificity of 92.9% and 100%, and 100.0% and 87.5%, respectively. 16S metagenomics using the assay software was not able to identify R. felis positive specimens, although manual BLAST_>99 did identify the species, but demonstrated sensitivity of 92.9% and specificity of 65.0%. No association of the detection rate of Rickettsia genus or R. felis, with the epidemiological data collected, was identified.

CONCLUSIONS

These observations suggest the occurrence of R. felis in fleas from pets in Attica, Greece, but PCR and sequencing assays varied considerably in sensitivity and specificity and a consensus methodology for assigning the positivity status is required to be established.

Serosurvey of IgG Antibodies against Bartonella henselae and Rickettsia typhi in the Population of Attica, Greece

Rickettsia typhi and Bartonella henselae are the causative agents of murine typhus and cat-scratch disease, respectively. A small-scale survey (N = 202) was conducted in the Attica region, Greece, for determining the prevalence rates of IgG antibodies against B. henselae and R. typhi by indirect fluorescence antibody test. IgG against B. henselae and R. typhi were present in 17.8% (36/202) and 4.5% (9/202) of the participants, respectively; co-occurring IgG against both B. henselae and R. typhi were detected in 3.5% (7/202), whereas only anti-B. henselae IgG in 14.3% (29/202), and only anti-R. typhi IgG in 1.0% (2/202). Titres 1/64, 1/128, 1/256, and 1/512, of anti-B. henselae IgG were identified in 6.4%, 4.5%, 4.5%, and 2.4%, whereas titres 1/40 and 1/80 of anti-R. typhi IgG were detected in 4.0%, and 0.5%, respectively. A positive association of anti-B. henselae IgG prevalence with a coastal area featuring a major seaport (p = 0.009) and with younger age (p = 0.046) was identified. The findings of this survey raise concern for exposure of the population of Attica to B. henselae and R. typhi, which should be considered in the differential diagnosis when compatible symptoms are present. Our results also suggest that seaports may represent high-risk areas for exposure to Bartonella spp.

In vitro activity of aztreonam/avibactam against a global collection of Klebsiella pneumoniae collected from defined culture sources in 2016 and 2017

OBJECTIVES

This study reports on the activity of aztreonam/avibactam (ATM-AVI) against a collection of Klebsiella pneumoniae collected in 2016 and 2017.

METHODS

Non-duplicate K. pneumoniae isolates were collected from four regions (Africa/Middle East, n = 785; Asia-Pacific, n = 1433; Europe, n = 4236; Latin America, n = 1499) and five culture sources (blood, n = 902; intra-abdominal, n = 992; urinary tract, n = 2148; skin and skin structure, n = 1409; lower respiratory tract, n = 2502). MICs were determined at a central laboratory using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodology. Susceptibility was determined using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints.

RESULTS

For all culture sources, against all K. pneumoniae, the highest rates of susceptibility were seen for amikacin (>84%), ceftazidime/avibactam (>94%), colistin (>92%) and meropenem (>83%), and >99.9% of isolates were inhibited at an ATM-AVI MIC of ≤4 mg/L. Among meropenem-resistant (MEM-R, n = 583) and meropenem-resistant metallo-β-lactamase-negative (MEM-R-MBLN; n = 469) isolates, susceptibility was highest to ceftazidime/avibactam (79.9% and 99.4%, respectively) and colistin (67.2% and 62.7%, respectively). All MEM-R-MBLN isolates from blood, intra-abdominal, urinary tract and skin and skin structure sources, and all but one isolate from respiratory sources, were inhibited at an ATM-AVI MIC of ≤2 mg/L. Against the meropenem-resistant metallo-β-lactamase positive (MEM-R-MBLP; n = 114) isolates, susceptibility to colistin was between 75.0% (urinary tract isolates) and 93.3% (lower respiratory tract isolates). All MEM-R-MBLP isolates were inhibited at an ATM-AVI MIC of ≤0.5 mg/L.

CONCLUSIONS

ATM-AVI is active against K. pneumoniae isolates from a range of culture sources across Africa/Middle East, Asia-Pacific, Europe and Latin America. ATM-AVI also has activity against MEM-R-MBLN and MEM-R-MBLP isolates.

Invasive infection from Kingella kingae: Not only arthritis

Kingella kingae is a known pathogen for osteoarticular infections in young children. However other invasive infections such as pneumonia in immunocompetent patients are scarcely described in literature. We present an unusual case of bacteremia and lower respiratory tract infection in a previously healthy infant, the first one described in Greek pediatric population. The pathogen was identified using both culture and molecular techniques

Evidence of Brucella melitensis DNA in the Microbiome of Ctenocephalides felis from Pet Cats in Greece

Cat fleas (Ctenocephalides felis) are the most prevalent ectoparasites of pet animals with cosmopolitan distribution, obligatory hematophagous, and may prey on humans to receive bloodmeals. We studied the microbiota of 100 flea-pools, containing C. felis, and collected from equal number of cats and dogs in the region of Attica, Greece, including Athens. The 16S metagenomics technique detected Brucella spp. nucleotide sequence that was identified as Brucella melitensis DNA by a real-time PCR, in five flea-pools, corresponding to five cats, one owned and the remaining four stray, residing in semiurban and urban areas, respectively. No definite conclusions can be drawn as to the pathway that led to the presence of B. melitensis in common fleas parasitizing cats. We suspect flea or cat contact with wild rodents, ubiquitous in various environments, which participate in the B. melitensis biology. The proximity of the cats and their fleas with humans and previous observations of flea potential to transmit B. melitensis in laboratory animals warrant a more elaborate research as to the vectorial dynamics, the ecological pathways resulting in pathogen carriage, and the risk for public health.

Results from the Survey of Antibiotic Resistance (SOAR) 2014-16 in Greece

Objectives

To determine antimicrobial susceptibility in isolates of Streptococcus pneumoniae and Haemophilus influenzae collected in 2014-16 from patients with community-acquired respiratory tract infections in Greece.

Methods

MICs were determined by CLSI broth microdilution and susceptibility assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

Results

A total of 99 S. pneumoniae and 52 H. influenzae isolates were collected. Overall, 36.4% of S. pneumoniae were penicillin susceptible by CLSI oral/EUCAST and 88.9% by CLSI intravenous (iv) breakpoints. All were fluoroquinolone susceptible with ≥94% of isolates also susceptible to amoxicillin, amoxicillin/clavulanic acid and ceftriaxone by CLSI and PK/PD breakpoints. Trimethoprim/sulfamethoxazole, cefuroxime, cefaclor and macrolides were less active, with rates of susceptibility of 83.8%, 69.7%, 50.5% and 49.5%, respectively, by CLSI. Generally susceptibility was the same or slightly lower by EUCAST, but the cefaclor difference was much greater. Among H. influenzae, 15.4% of isolates were β-lactamase positive. Susceptibility to amoxicillin/clavulanic acid, ceftriaxone, cefuroxime and the fluoroquinolones was seen in >95% of isolates by CLSI criteria. Susceptibility to azithromycin was seen in 94.2% of isolates using CLSI breakpoints, but clarithromycin susceptibility was lower (61.5%). However, susceptibility to both macrolides was seen in <5% of isolates by PK/PD and EUCAST criteria. Susceptibility to trimethoprim/sulfamethoxazole was seen in 71.2% of isolates.

Conclusions

Owing to the high prevalence of macrolide resistance among S. pneumoniae and the reduced activity of clarithromycin against H. influenzae, it appears that these agents are not appropriate as monotherapy for community-acquired pneumonia in Greece. Amoxicillin/clavulanic acid, on the other hand, maintained excellent in vitro activity and, as opposed to the similarly effective fluoroquinolones, is safe to use in paediatric patients.

Changes in the rates and population structure of methicillin-resistant Staphylococcus aureus (MRSA) from bloodstream infections: A single-centre experience (2000-2015)

OBJECTIVES

The aim of this study was to assess the rate of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSIs) and the population structure of MRSA isolates recovered between 2000-2015 in a tertiary-care hospital in Athens, Greece.

METHODS

Non-duplicate MRSA blood isolates recovered during the study period were examined. Antimicrobial susceptibility testing was performed by Kirby-Bauer and gradient strip methods. Carriage of PVL and mecA genes was examined by PCR. Genetic relatedness of the isolates was studied by SCCmec, spa and multilocus sequence typing.

RESULTS

A total of 398 MRSA BSI cases were identified. A decreasing trend in incidence from 1.69/10 000 patient-days in 2000 to 1.39/10 000 patient-days in 2015 (P=0.038) and in prevalence from 64.7% to 36.4% (P=0.008), respectively, was observed, whereas the incidence of methicillin-susceptible S. aureus BSI increased. MRSA isolates exhibiting resistance to common antistaphylococcal agents (excluding glycopeptides and the newer antistaphylococcals) decreased from 84.8% in 2000 to 0% in 2011 and were progressively 'replaced' by more susceptible phenotypes. A strong association between antimicrobial resistance phenotype and molecular type was observed. The pandemic HA-MRSA clone ST239-III progressively declined in parallel with increasing isolation frequency of two clonal complexes (CCs): HA-MRSA CC5, with the majority of isolates belonging to ST5-II; and CA-MRSA CC80, represented mainly by ST80-IV-t044, PVL+.

CONCLUSION

The decline in MRSA BSI rates observed in our institution was associated with changes in population structure of the organism. This decline may be related to biological properties of the prevailing MRSA clones.

Combination of conventional culture, vial culture, and broad-range PCR of sonication fluid for the diagnosis of prosthetic joint infection

We assessed the value of conventional culture, vial culture, and broad-range PCR of the sonication fluid (SF), individually or in combinations, for the diagnosis of prosthetic joint infection (PJI). We studied 114 consecutive patients (median age:72.5 years, males: 28.07%) undergoing removal of a total knee or hip prosthesis. By non-microbiologic criteria, 87 patients had aseptic failure, and 27 PJI. All patients had periprosthetic tissue culture, sonication of prosthesis, and study of SF by conventional and vial culture, and PCR. Compared to tissue culture, each test was significantly more sensitive and less specific. If only one test was positive, the sensitivity was 88.46% and specificity 64.29%. If all three SF tests were positive, sensitivity, and NPV were decreasing (34.6% and 80.23%), but specificity and PPV were increasing up to 98.57% and 90.9%, respectively, outperforming tissue culture. A triple negative test practically excluded PJI.

Prevalence of Mycoplasma genitalium and other sexually-transmitted pathogens among high-risk individuals in Greece

Background

The aim of the present study was to determine the prevalence of Mycoplasma genitalium (MG) infection among individuals at high risk for sexually-transmitted diseases (STDs) at a major urban STD clinic in Athens, in view of the lack of data pertaining to this infection in Greece.

Methods

Urethral and cervical samples from 176 individuals consecutively attending the clinic and agreeing to participate were prospectively collected and tested for MG infection using conventional PCR and TaqMan Real-Time PCR. All individuals were also examined for alternative STD pathogens.

Results

A total of 161 individuals (91.5%) reported symptoms, while 15 individuals (8.5%) were asymptomatic. MG was detected in 5.7% (10/176) of the total population and in 5.6% (9/161) of those with symptoms, corresponding to 5.7% (5/87) of symptomatic men and 5.4% (4/74) of symptomatic women. Among symptomatic males, 3.4% (3/87) displayed MG mono-infection. The median age of MG infected individuals was 25 years (IQR 21.5-29.5 years). Individuals infected with MG were more likely to be coinfected with Ureaplasma spp. [OR=5.12, 95%CI, 1.27-20.57] (p=0.017). MG infection was also more common among individuals who had received antibiotics in the previous 15 days [OR=6.04, 95%CI, 1.37-26.64] (p=0.035).

Conclusion

MG was found to represent an important microbial pathogen among patients presenting with symptoms of urethritis or cervicitis in Greece. Consideration of MG as cause of STD seems crucial in diagnostic algorithms and treatment strategies.

Magnetic nanoparticle-enhanced PCR for the detection and identification of Staphylococcus aureus and Salmonella enteritidis

This paper evaluated magnetic nanoparticle-enhanced PCR for the detection and identification of Staphylococcus aureus and Salmonella enteritidis. Two different types of magnetic nanoparticles designated MPIO (iron concentration 2.5 mg/ml, size 1 µm) and NP (iron concentration 8.7 mg/ml, size 60 nm), both conjugated with S. aureus or S. enteritidis antibodies were evaluated as an enrichment procedure for PCR-detection of the pathogens in Trypticase Soy Broth, milk, blood and meat broth. Bacterial suspensions (1.5x108 cfu/ml) were prepared and serial diluted 10-1. The MPIO and NP nanoparticles were added, followed by incubation for 1 hour at room temperature, magnetic separation of the pellet, DNA extraction and PCR, targeting the femA and invA sequences. The nanoparticle-free and the NP-supplemented dilutions were positive down to the 1.5x102 cfu/ml concentration for both bacteria. The MPIO-supplemented dilutions were positive down to approx. 2x100 cfu/ml concentration, respectively. Bacteria-free TSB was negative by PCR. MPIO nanoparticles (size 1 µm) enhanced the detection of S. aureus and S. enteritidis by PCR, whilst NP nanoparticles (size 60 nm) did not, thus indicating that the size of the magnetic nanoparticles play a significant role in the enrichment procedure.

Pneumonia and Pleural Empyema due to a Mixed Lactobacillus spp. Infection as a Possible Early Esophageal Carcinoma Signature

Lactobacilli are human commensals found in the gastrointestinal and genitourinary tract. Although generally conceived as non-pathogenic microorganisms, the existence of several reports implicating them in certain severe pathological entities renders this species as opportunistic pathogens. The case of a 58-year-old woman with mixed Lactobacillus infection is described. The patient was admitted in an outpatient clinic with community acquired pneumonia, and on the third day of hospitalization she presented rapid pneumonia deterioration. Subsequent imaging techniques revealed increased pleural empyema in alignment with the general deterioration of her clinical condition. Pleural fluid culture revealed the presence of Lactobacillus delbrueckii and Lactobacillus gasseri and the infection was successfully treated with clindamycin. Five months after hospital discharge and an overall good condition, the patient developed signs of dysphagia and upon re-admission an inoperable esophageal carcinoma was diagnosed. The patient succumbed to the cancer 11 months later. Herein, we report for the first time a mixed respiratory infection due to lactobacilli, possibly associated with a formerly unveiled esophageal malignancy.

18-Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography scan for monitoring the therapeutic response in experimental Staphylococcus aureus foreign-body osteomyelitis

Background

18-Fluoro-2-deoxy-d-glucose positron emission tomography combined with computed tomography (¹⁸F-FDG PET/CT) scan is useful for diagnosis of osteoarticular infections. Whether ¹⁸F-FDG PET/CT scanning may be used for therapeutic monitoring is not clear. The objective of this study was to develop ¹⁸F-FDG PET/CT scanning for monitoring therapeutic response to antimicrobials in experimental Staphylococcus aureus osteomyelitis.

Methods

A total of 22 rabbits were studied. In 20 animals, the right tibia was inoculated intraoperatively with S. aureus. Two control animals were inoculated with normal saline. A needle was placed in the tibia as a foreign body. Infection was allowed to develop for 21 days when ¹⁸F-FDG PET/CT was performed, the needle was removed, and bone specimens were cultured to confirm infection. Antimicrobial therapy with daptomycin was initiated in all successfully infected animals for 1, 3, or 6 weeks. Following completion of treatment, a second ¹⁸F-FDG PET/CT was performed, animals were euthanized, and infected tibias were harvested for quantitative cultures and histology. A positive scan was defined as ¹⁸F-FDG signal activity greater in the infected tibia than that of the contralateral non-infected control tibia. Therapeutic response was measured by the change of ¹⁸F-FDG signal activity in the infected tibia.

Results

All successfully infected animals (n = 14), with microbiologically and/or histologically confirmed osteomyelitis, had positive ¹⁸F-FDG PET/CT scans, while the two control animals had negative scans despite the presence of the foreign body [mean maximum standardized uptake value (SUVmax) (±SD) values 2.96 (±0.80) vs. 1 (±1.10), respectively, P = 0.04]. In the 14 successfully infected animals, the mean SUVmax was significantly higher in the infected compared to the uninfected tibia (P < 0.0001). A SUVmax of 1.4, when used as a cutoff for infection, yielded a diagnostic accuracy of 93 %. At the end of treatment, successfully treated animals and saline controls had a negative ¹⁸F-FDG PET/CT scan (n = 4), while animals with persistent infection despite treatment (n = 12) had a positive ¹⁸F-FDG PET/CT scan (SUVmax 1.0–3.0) (p < 0.001). SUVmax values were significantly reduced after 42 days of treatment from 3.15 ± 0.5 (day 7) to 1.71 ± 0.37 (day 42) (p = 0.05).

Conclusions

¹⁸F-FDG PET/CT scan is a sensitive and specific tool in therapeutic monitoring of experimental foreign-body osteomyelitis.

MLST typing of antimicrobial-resistant Propionibacterium acnes isolates from patients with moderate to severe acne vulgaris

Molecular typing data on antimicrobial-resistant Propionibacterium strains are limited in the literature. We examined antimicrobial resistance profiles and the underlying resistance mechanisms in Propionibacterium spp. isolates recovered from patients with moderate to severe acne vulgaris in Greece. The clonallity of the resistant Propionibacterium acnes isolates was also investigated. Propionibacterium spp. isolates were detected using Tryptone-Yeast Extract-Glucose (TYG) agar plates supplemented with 4% furazolidone. Erythromycin, clindamycin, vancomycin, penicillin, co-trimoxazole, doxycycline, minocycline and ciprofloxacin MICs were determined using the gradient strip method. Erythromycin, clindamycin and tetracycline mechanisms of resistance were determined using PCR and sequencing of the domain V of 23S rRNA and 16S rRNA, as well as the presence of the ermX gene. Typing was performed using the multi locus sequence typing (MLST) methodology. Seventy nine isolates from 76 patients were collected. Twenty-three isolates (29.1%) exhibited resistance to erythromycin and clindamycin, while two additional isolates (2.5%) were resistant only to erythromycin. Resistance to tetracycline was not detected. The underlying molecular mechanisms were point mutations A2059G and A2058G. MLST typing of the P. acnes resistant isolates revealed that lineage type IA1 (ST-1, 3 and 52) prevailed (12/18; 66.7%), whilst lineage type IA2 (ST-2 and 22) accounted for five more isolates (27.8%). Susceptible isolates were more evenly distributed between ST types. Propionibacterium spp. from moderate to severe acne vulgaris in Greece are frequently resistant to erythromycin/clindamycin but not to tetracyclines, mainly due to the point mutations A2059G and A2058G. P. acnes resistant isolates were more clonally related than susceptible ones and belonged to a limited number of MLST types.

A prospective study on bacterial and atypical etiology of acute exacerbation in chronic obstructive pulmonary disease

ABSTRACT 

Aim: The bacterial and atypical etiology of acute exacerbations of chronic obstructive pulmonary disease was investigated and the diagnostic techniques used were compared among 92 hospitalized patients. Materials & methods: Sputum specimens were investigated using culture and PCR, serological status evaluation was performed and the inflammatory profile was associated with the microbiological results. Results & conclusion: The majority of the patients (65.2%) had very severe airway obstruction. The most common bacteria were Haemophilus influenzae and Pseudomonas aeruginosa (23.9 and 14.1%, respectively). Acinetobacter baumannii- and P. aeruginosa-positive cultures were associated with prolonged hospitalization and severe airway obstruction (p = 0.03 and 0.031, respectively). Chlamydia pneumoniae or Mycoplasma pneumoniae infection was diagnosed in four and two patients, respectively. Discrepant results were detected between PCR and serology, especially regarding C. pneumoniae.

Detection of Bacteria Bearing Resistant Biofilm Forms, by Using the Universal and Specific PCR is Still Unhelpful in the Diagnosis of Periprosthetic Joint Infections

Intraoperative conventional bacteriological cultures were compared with different polymerase chain reaction (PCR) methods in patients with total joint arthroplasties. The isolated bacteria were investigated for biofilm formation, and the biofilm forming strains, in their planktonic and biofilm forms, were further tested for their antimicrobial resistance against several clinically important antimicrobials. Forty four bone and joint samples were included and classified as infected or non-infected according to standard criteria for periprosthetic hip and knee infections. For the bacteriological diagnosis, conventional culture, two types of universal PCR and species specific PCR for three selected pathogens (Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa) were applied. Biofilm formation determination was performed by the tissue culture plate method. Antimicrobial susceptibility of the planktonic bacteria was performed by the minimal inhibitory concentration determination and, of the biofilm forms, by the minimal inhibitory concentration for bacterial regrowth from the biofilm. Twenty samples were culture positive, with S. epidermidis, S. aureus, or P. aeruginosa. All PCR methods were very ineffective in detecting only one pathogen. All isolates were biofilm positive and their biofilm forms, were highly resistant. In this study, compared to PCR, culture remains the "gold standard." The biofilm formation by the causative bacteria and the concomitant manifold increased antimicrobial resistance may explain the clinical failure of treatment in some cases and should be considered in the future for therapeutic planning.

Incidence and risk factors for central vascular catheter-related bloodstream infections in a tertiary care hospital

This study evaluated the incidence of colonization and infection related to Central Vascular Catheters (CVC) in a tertiary care Greek hospital, as well as risk factors associated with catheter-related bloodstream infection (CRBSI). A total of 340 CVCs, were studied in relation to patient clinical and epidemiological data, CVC characteristics, and microbiological culture results. Risk factors were assessed. Pulsed field gel electrophoresis was used for the investigation of the clonal relationship of the isolates. The incidence for CRBSI and catheter colonization (CC) was 11.47 and 19.49 per 1,000 catheter days, respectively. Risk factors independently associated with CRBSI were use of corticosteroids, diabetes mellitus, solid organ neoplasm, long duration of catheterization, and changing the CVC dressing at intervals of 48 hours or more. Risk factors for CC were diabetes mellitus, hospitalization in ICU, and prolonged hospitalization. The predominant microorganisms isolated from CRBSI episodes were coagulase-negative staphylococci. All patients with CVC require constant infection surveillance and appropriate care by trained medical staff. Use of CVC for the shortest time possible, good hand hygiene and change of CVC dressing at intervals of less than 48 hours are infection prevention practices that need to be followed.

High level of heterogeneity among Listeria monocytogenes isolates from clinical and food origin specimens in Greece

In order to examine the genetic variation of clinical and food isolates of Listeria monocytogenes in Greece, a total of 61 L. monocytogenes non-duplicate isolates, recovered from clinical specimens (n=19) and food (n=42), were serotyped and genotyped using two different Random Amplification of Polymorphic DNA (RAPD) protocols and Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Serotype group 4b, 4d, 4e prevailed (39.4%), among both clinical and food isolates, followed by serotype group 1/2a, 3a (23.0%), which nevertheless was detected only among food isolates. The most discriminatory typing protocol was MLVA, which grouped four isolates into two pairs, while the remaining isolates produced unique fingerprints. Similar results were obtained when taking into account the combination of the two RAPD protocols (Simpson index 0.999); six isolates were grouped into three pairs, two of which were the pairs that were identified also by MLVA. Single use of each RAPD protocol resulted in inferior discrimination (Simpson index 0.978 and 0.997, respectively). In conclusion, the two molecular procedures, MLVA, and the combined RAPD protocols, produced similar results, showing that L. monocytogenes isolates from clinical and food specimens were highly heterogenous and that clustering was very uncommon.

Cutaneous infection caused by Bacillus anthracis in Larissa, Thessaly, Central Greece, July 2012

In July 2012, a confirmed case of cutaneous anthraxinfection in a stockbreeder in the prefecture of Larissa, Thessaly, Central Greece was reported. The investigation revealed five related deaths in animals (two dogs and three sheep). Control measures have been taken immediately in order to prevent further spread in humans and animals.

Epidemiological characteristics of infections caused by Bacteroides, Prevotella and Fusobacterium species: a prospective observational study

In order to investigate differences among infections due to Gram-negative anaerobic bacteria (Bacteroides, Prevotella and Fusobacterium spp.), clinical, epidemiological, and microbiological data were collected and evaluated from 206 anaerobic infections. The most frequently isolated species was Bacteroides fragilis. The majority of the cases were intra-abdominal infections (49%) followed by skin and soft tissue infections (24.7%). Logistic regression analysis showed that Bacteroides spp. strains were more often isolated from intra-abdominal infections (p = 0.002), whereas Prevotella spp. were isolated more frequently from cases with shorter duration of hospitalization (p = 0.026), and less frequently from bloodstream infections (p = 0.049). In addition, Bacteroides spp. were associated with coinfection due to Enterobacteriaceae species (p = 0.007), whereas Prevotella spp. were associated with coinfection due to Staphylococcus spp. (p = 0.002). Patients with an infection due to B. fragilis, were more frequently admitted in a general surgical ward (p = 0.017), or have been treated with a 2nd generation cephalosporin before anaerobic infection onset (p = 0.05). Total mortality was 10.9% and was associated with bacteremia (p = 0.026), and hematological (p = 0.028), or solid organ malignancy (p = 0.007). Metronidazole resistance was detected only among Prevotella spp. (16.2%) and B. fragilis group (0.8%) isolates. In conclusion, this study indicated differences between infections due to the most frequently isolated Gram-negative anaerobic species, differences that may affect the design and implementation of empirical antimicrobial chemotherapy guidelines.

In vitro activity of tigecycline against 2423 clinical isolates and comparison of the available interpretation breakpoints

MICs to tigecycline and 12 antimicrobials were performed by microdilution method, against 2423 nonduplicate pathogens recently isolated in 17 Greek hospitals. The Food and Drug Administration (FDA) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria were used comparatively for interpretation of tigecycline MICs. Tigecycline exhibited potent in vitro activity against the majority of the isolates tested. (MIC(90) values of 0.5, 1, 2, 0.125, 1, 0.25, 0.125, and 1 mg/L were observed for Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Moraxella catarrhalis, Acinetobacter spp., Staphylococcus aureus, Enterococcus spp., and Streptococcus pneumoniae isolates, respectively.) Tigecycline activity was the same, irrespective of the resistance profile to other antimicrobials (Gram-negative pathogens susceptible or resistant to imipenem, Enterococcus spp., S. aureus, or S. pneumoniae isolates, susceptible or resistant to vancomycin, methicillin or penicillin, respectively). Interpretation using EUCAST and FDA breakpoints differed among isolates of K. pneumoniae and Enterobacter spp. having tigecycline MICs of 2 to 4 mg/L. In conclusion, tigecycline exhibited potent activity against pathogens recently isolated in a region that experiences high antimicrobial resistance rates. Indications that the available criteria might categorize differently tigecycline susceptibility status in K. pneumoniae and Enterobacter spp. isolates were also detected.

Differences in the changes in resistance patterns to third- and fourth-generation cephalosporins and piperacillin/tazobactam among Klebsiella pneumoniae and Escherichia coli clinical isolates following a restriction policy in a Greek tertiary care hospital

The aim of the present study was to investigate whether replacement of broad-spectrum cephalosporins (CEPs) by piperacillin/tazobactam (TZP) as first-line empirical therapy may have an effect on beta-lactam resistance among Klebsiella pneumoniae and Escherichia coli in a tertiary care hospital. Data regarding CEP and TZP consumption and resistance were collected on a bimonthly basis during an open-label 2-year (1 year observational and 1 year interventional) study. Consumption of ceftazidime was reduced by 64.5%. In contrast, consumption of the other third-generation CEPs (cefotaxime and ceftriaxone) remained almost stable, whereas an increase in consumption of TZP by 2.8-fold was observed. A significant decrease in resistance to third-generation cephalosporins among K. pneumoniae isolates was observed, and the incidence of extended-spectrum beta-lactamase-producing isolates was notably reduced. These findings were less evident among E. coli isolates. Despite the significant increase in TZP consumption, the respective resistance rates of both bacterial species examined have remained almost unchanged.

Differences in the evolution of imipenem susceptibility among Klebsiella pneumoniae and Escherichia coli isolates during a 6-year period in a tertiary care hospital

The evolution of imipenem disk-diffusion susceptibility results of 2652 strains of Klebsiella pneumoniae and 7596 Escherichia coli isolated during the period 2000-2005 were analysed. Screening for production of metallo-beta-lactamases was performed using the EDTA-synergy method. The percentage rate of K. pneumoniae isolates having a zone diameter < or =25 mm increased from 20% in 2000 to 41% in 2005, whereas the respective rate of isolates having a zone diameter > or =30 mm decreased from 48 to 23%. These changes were more evident during 2000-2002, followed in 2003 by the isolation of the first imipenem-resistant strains. Regarding E. coli, a similar decrease was observed (the rates of isolates having a zone diameter < or =25 mm and > or =30 mm changed from 7% and 68% in 2000, to 32% and 36% in 2005, respectively) following the respective changes of K. pneumoniae. A total of 20 K. pneumoniae strains, but no E. coli, were confirmed as metallo-beta-lactamase producers. In conclusion, a decrease of the imipenem susceptibility prior to the isolation of the first resistant strains in a tertiary care hospital was detected, as well as differences in this decrease between the two species. These findings indicate that monitoring of the evolution of imipenem susceptibility in real-time may help in unveiling forthcoming resistance and in implementing the appropriate diagnostic techniques.

Two cases of infections due to multidrug-resistant Bacteroides fragilis group strains

Bacteroides fragilis group strains are still considered susceptible to most antimicrobial agents used for the treatment of infections caused by anaerobic organisms. We describe two cases of infections due to isolates simultaneously resistant to clindamycin, tetracycline, cefoxitin, piperacillin-tazobactam, and imipenem and, in one of the two cases, to metronidazole. Such infections, although still rare, do exist and tend to complicate treatment.

Septic arthritis due to Roseomonas mucosa in a rheumatoid arthritis patient receiving infliximab therapy

We report a case of septic arthritis due to Roseomonas mucosa in a rheumatoid arthritis patient receiving infliximab therapy. This is the first report of septic arthritis due to R. mucosa, and infliximab therapy might be a predisposing factor because this infection was never reported in the pre-anti-tumor necrosis factor alpha therapy period.

In vitro activities of tigecycline against recently isolated Gram-negative anaerobic bacteria in Greece, including metronidazole-resistant strains

The in vitro activity of tigecycline was compared with those of benzylpenicillin, piperacillin + tazobactam, cefoxitin, imipenem, metronidazole, clindamycin, and tetracycline against 249 Gram-negative anaerobic bacteria (158 Bacteroides fragilis group, 27 non-fragilis Bacteroides spp., 44 Prevotella spp., and 20 miscellaneous), recently isolated from 8 general hospitals in Athens, Greece. Overall tigecycline MIC(50) and MIC(90) were 0.25 and 2 mg/L, respectively, whereas B. fragilis group MIC(50) and MIC(90) were 0.5 and 4 mg/L, respectively. In total, 93% of the isolates were susceptible to tigecycline (MIC </= 4 mg/L) and no high-level resistance (MIC >/= 32 mg/L) was detected. In addition, tigecycline exhibited good activity against metronidazole- and tetracycline-resistant isolates (MIC(90), 0.5 and 8 mg/L, respectively). In summary, tigecycline exhibits good in vitro activity against Gram-negative anaerobic bacteria isolated in Greece, as well as stability to the most common occurring resistance mechanisms, attributes that make this parenteral agent an attractive alternative for use against infections involving these microorganisms.

Multicentre survey of the in-vitro activity of seven antimicrobial agents, including ertapenem, against recently isolated Gram-negative anaerobic bacteria in Greece

The in-vitro activities of penicillin, ticarcillin-clavulanic acid, cefoxitin, imipenem, ertapenem, metronidazole and clindamycin were evaluated against 138 Gram-negative anaerobic isolates (82 Bacteroides fragilis group, 17 non-fragilis Bacteroides spp., 31 Prevotella spp., four Fusobacterium spp., two Veillonella spp., one Porphyromonas sp. and one Tissierella praeacuta) collected from six general hospitals in Athens, Greece. Overall rates of non-susceptibility (both resistant and intermediately-resistant) to penicillin and ticarcillin-clavulanic acid were 81.8% and 2.3%, respectively. The rates of non-susceptibility to cefoxitin and clindamycin were 30.3% and 31.1%, respectively, and that for metronidazole was 4.3% (four Prevotella spp. isolates, one Porphyromonas sp. isolate and one B. fragilis isolate). Only the single B. fragilis isolate was nim-positive by PCR. Only one B. fragilis isolate was resistant to both carbapenems tested, while six more Bacteroides spp. isolates were imipenem-susceptible and ertapenem-non-susceptible. The MIC range, MIC(50) and MIC(90) values were comparable for imipenem and ertapenem, although ertapenem MIC(90)s were one or two two-fold dilutions higher.

Dissemination of vancomycin-resistant enterococci among haemodialysis patients in Athens, Greece

OBJECTIVES

Vancomycin-resistant enterococci (VRE) may colonize haemodialysis patients, but their epidemiology in this population is not well defined. Within the few last years, VRE strains have emerged and are increasingly isolated in the nosocomial environment in Greece, but colonization of dialysis patients has never been evaluated before. This study sought to determine the epidemiology of VRE colonization within this high-risk population and define the risk factors.

MATERIALS AND METHODS

During a 4 month period, rectal swabs or faecal specimens were collected from 334 consecutive outpatients, who were treated at four independent dialysis units located in the same area of Athens and referring patients to the same local hospital. The relatedness of isolates was defined by molecular typing, and demographic and clinical patient data were recorded.

RESULTS

Thirteen multiresistant Enterococcus faecium vanA strains were isolated corresponding to a colonization frequency of 3.9%. They were separated into seven clusters: type A (two strains), type B (six strains) and types C to G (one strain each). Type B strains originated from three units, while a single unit demonstrated four type B and two type A strains. Univariate statistical analysis revealed that prior hospitalization (P=0.001), prior administration of antimicrobials (P=0.026) and male gender (P=0.019) were associated with VRE colonization.

CONCLUSIONS

In Greece, haemodialysis patients are colonized with VRE at a low frequency. The predominance of one clone and its isolation from several units strongly indicate interfacility transmission of strains, most probably within a health care environment shared by all patients.

Ruling out Bacillus anthracis

Optimization of methods for ruling out Bacillus anthracis leads to increased yields, faster turnaround times, and a lighter workload. We used 72 environmental non–B. anthracis bacilli to validate methods for ruling out B. anthracis. Most effective were horse blood agar, motility testing after a 2-h incubation in trypticase soy broth, and screening with a B. anthracis–selective agar.