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.

Adaptation of Brucella melitensis Antimicrobial Susceptibility Testing to the ISO 20776 Standard and Validation of the Method.

Brucellosis, mainly caused by Brucella (B.) melitensis, is associated with a risk of chronification and relapses. Antimicrobial susceptibility testing (AST) standards for B. melitensis are not available, and the agent is not yet listed in the EUCAST breakpoint tables. CLSI recommendations for B. melitensis exist, but they do not fulfill the requirements of the ISO 20776 standard regarding the culture medium and the incubation conditions. Under the third EU Health Programme, laboratories specializing in the diagnostics of highly pathogenic bacteria in their respective countries formed a working group within a Joint Action aiming to develop a suitable method for the AST of B. melitensis. Under the supervision of EUCAST representatives, this working group adapted the CLSI M45 document to the ISO 20776 standard after testing and validation. These adaptations included the comparison of various culture media, culture conditions and AST methods. A Standard Operation Procedure was derived and an interlaboratory validation was performed in order to evaluate the method. The results showed pros and cons for both of the two methods but also indicate that it is not necessary to abandon Mueller-Hinton without additives for the AST of B. melitensis.

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.

Clinical Application of the Novel Cell-Based Biosensor for the Ultra-Rapid Detection of the SARS-CoV-2 S1 Spike Protein Antigen: A Practical Approach.

The availability of antigen tests for SARS-CoV-2 represents a major step for the mass surveillance of the incidence of infection, especially regarding COVID-19 asymptomatic and/or early-stage patients. Recently, we reported the development of a Bioelectric Recognition Assay-based biosensor able to detect the SARS-CoV-2 S1 spike protein expressed on the surface of the virus in just three minutes, with high sensitivity and selectivity. The working principle was established by measuring the change of the electric potential of membrane-engineered mammalian cells bearing the human chimeric spike S1 antibody after attachment of the respective viral protein. In the present study, we applied the novel biosensor to patient-derived nasopharyngeal samples in a clinical set-up, with absolutely no sample pretreatment. More importantly, membrane-engineered cells were pre-immobilized in a proprietary biomatrix, thus enabling their long-term preservation prior to use as well as significantly increasing their ease-of-handle as test consumables. The plug-and-apply novel biosensor was able to detect the virus in positive samples with a 92.8% success rate compared to RT-PCR. No false negative results were recorded. These findings demonstrate the potential applicability of the biosensor for the early, routine mass screening of SARS-CoV-2 on a scale not yet realized.

Molecular Evidence of a Broad Range of Pathogenic Bacteria in Ctenocephalides spp.: Should We Re-Examine the Role of Fleas in the Transmission of Pathogens?

The internal microbiome of common cat and dog fleas was studied for DNA evidence of pathogenic bacteria. Fleas were grouped in pools by parasitized animal. DNA was extracted and investigated with 16S metagenomics for medically relevant (MR) bacteria, based on the definitions of the International Statistical Classification of Diseases and Related Health Problems (WHO). The MR bacterial species totaled 40, were found in 60% of flea-pools (N = 100), and included Acinetobacterbaumannii, Bacteroidesfragilis, Clostridiumperfringens, Enterococcusfaecalis, E. mundtii, Fusobacteriumnucleatum, Haemophilusaegyptius, Kingellakingae, Klebsiellapneumoniae, Leptotrichiabuccalis, L. hofstadii, Moraxellalacunata, Pasteurellamultocida, Propionibacteriumacnes, P. propionicum, Proteusmirabilis, Pseudomonasaeruginosa, Rickettsiaaustralis, R. hoogstraalii, Salmonellaenterica, and various Bartonella, Staphylococcus, and Streptococcus species. B. henselae (p = 0.004) and B. clarridgeiae (p = 0.006) occurred more frequently in fleas from cats, whereas Rickettsiahoogstraalii (p = 0.031) and Propionibacteriumacnes (p = 0.029) had a preference in fleas from stray animals. Most of the discovered MR species can form biofilm, and human exposure may theoretically occur through the flea-host interface. The fitness of these pathogenic bacteria to cause infection and the potential role of fleas in the transmission of a broad range of diseases should be further investigated.

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.

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.

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.

Colistin resistance in carbapenemase-producing Klebsiella pneumoniae bloodstream isolates: Evolution over 15 years and temporal association with colistin use by time series analysis.

Colistin is often the only available treatment option against infections caused by carbapenemase-producing Klebsiella pneumoniae (CP-Kp). In this study, the evolution of colistin resistance among CP-Kp and its relationship with colistin use in a tertiary-care hospital in Athens, Greece, was investigated. All CP-Kp blood isolates recovered between January 2002 and June 2016 were tested for susceptibility to colistin by agar dilution and broth microdilution methods. Data on colistin use were collected from the pharmacy database. Time series of colistin use and resistance were analysed using the Box and Jenkins method. A transfer function model was built to quantify the dynamic relationship between colistin use and resistance. Overall, 313 CP-Kp isolates were identified. The percentage colistin resistance increased from 0% in 2002 to 26.9% in 2016 (R2 = 0.5, P < 0.01). A temporal association between colistin use and resistance was observed; an increase in colistin use by 1 DDD/100 patient-days led to a 0.05 increase in the incidence rate of colistin resistance. The time lag between the effect of colistin use on subsequent variations in colistin resistance was 3 months. Colistin use and prior levels of colistin resistance could explain 69% of colistin resistance; in the remaining 31%, other factors might have played a role. The results presented here demonstrate a significant temporal association between colistin use and colistin resistance. These findings have important implications in implementing strategies to contain colistin resistance.

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.

Osteostimulative calcium phosphosilicate biomaterials partially restore the cytocompatibility of decontaminated titanium surfaces in a peri-implantitis model.

Bacterial peri-implant biofilms, and the chemotherapeutics for their removal alter titanium surface cytocompatibility. In this study we aimed to assess the adjunctive use of an osteostimulative biomaterial utilizing a peri-implantitis model under the hypothesis that it will increase cell migration towards treated titanium surfaces. Acid-etched titanium surfaces were inoculated with a multi-species biofilm model and treated with 1.5% NaOCl in a previously characterized in vitro peri-implantitis model. Cell migration of MG63 cells towards the treated titanium surface (CTRL) was significantly reduced following inoculation with biofilm and chemotherapeutic treatment as compared to sterile controls. Addition of a tricalcium phosphate biomaterial (TCP) as a control for Ca+2 had a small non-significant effect, while BG significantly increased MG63 chemotaxis to titanium to levels comparable to sterile (STE). Similarly, cell viability at 5 days was increased in BG and TCP as compared to CTRL. SEM imaging confirmed the improved cytocompatibility of BG and TCP surfaces as compared to CTRL. Osteostimulative BG exhibited a strong chemotactic effect to osteoblasts, which was stronger than what was expected due to the chemotactic effect of Ca+2 alone (TCP). In addition, substantially increased cell attachment and viability was found on treated implant surfaces as compared to CTRL. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2645-2652, 2018.

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 ((18)F-FDG PET/CT) scan is useful for diagnosis of osteoarticular infections. Whether (18)F-FDG PET/CT scanning may be used for therapeutic monitoring is not clear. The objective of this study was to develop (18)F-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 (18)F-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 (18)F-FDG PET/CT was performed, animals were euthanized, and infected tibias were harvested for quantitative cultures and histology. A positive scan was defined as (18)F-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 (18)F-FDG signal activity in the infected tibia. RESULTS: All successfully infected animals (n = 14), with microbiologically and/or histologically confirmed osteomyelitis, had positive (18)F-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 (18)F-FDG PET/CT scan (n = 4), while animals with persistent infection despite treatment (n = 12) had a positive (18)F-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: (18)F-FDG PET/CT scan is a sensitive and specific tool in therapeutic monitoring of experimental foreign-body osteomyelitis.

Bronchiectasis exacerbations: The role of atypical bacteria, respiratory syncytial virus and pulmonary function tests.

BACKGROUND: Aside from the known role of common bacteria, there is a paucity of data regarding the possible role of atypical bacteria and viruses in exacerbations of non-cystic fibrosis bronchiectasis. OBJECTIVE: To explore the possible role of atypical bacteria (namely, Mycoplasma pneumoniae and Chlamydophila pneumoniae) and respiratory syncytial virus (RSV) as causative agents of bronchiectasis exacerbations. METHODS: A cohort of 33 patients was studied over a two-year period (one year follow-up for each patient). Polymerase chain reaction for the detection of M pneumoniae, C pneumoniae and RSV in bronchoalveolar lavage samples were performed during all visits. Antibody titres (immunoglobulin [Ig]M and IgG) against the aforementioned pathogens were also measured. In addition, cultures for common bacteria and mycobacteria were performed from the bronchoalveolar lavage samples. RESULTS: Fifteen patients experienced a total of 19 exacerbations during the study period. Although RSV was detected by polymerase chain reaction during stable visits in four patients, it was never detected during an exacerbation. M pneumoniae and C pneumoniae were never detected at stable visits or during exacerbations. IgM antibody titres for these three pathogens were negative in all patient visits. CONCLUSIONS: Atypical pathogens and RSV did not appear to be causative agents of bronchiectasis exacerbations.