Assessment of air purifier on efficient removal of airborne bacteria, Staphylococcus epidermidis, using single-chamber method.

We evaluated the efficiency of an air purifier using the single-chamber method for the effective removal of airborne Staphylococcus epidermidis, a nosocomial infection-causing bacterium. In this experiment, the bacterial strain S. epidermidis was injected using a nebulizer into the test chamber, which was similar to a consumer living space (60 m3). The microbial sampling was conducted via the air sampler method, and the reduction in S. epidermidis growth was monitored by performing three consecutive tests. Initially, a blank test was conducted to determine the natural decay rate and calibrate the experimental setup. After injecting the bacterial strain from 1240 to 11180 CFU per unit volume (m3), the natural decay rate showed a maximum deviation of 3.1% with a sampling error of 1.1% p at a confidence level of 95%. In addition, the particle size distribution in the test chamber was found to range from 0.3 to 5.0 µm, and a subsequent decrease in large-sized particles was observed with the operation of the air purifier, which is the size similar to that of suspended airborne bacteria. This can be used to assess the performance of the air purifier by calibrating the natural reduction value to the reduced operation value. Thus, the single-chamber technique is a promising approach for analyzing the removal efficacy of airborne bacteria from indoor air.

Simple and economical method for identification and speciation of Staphylococcus epidermidis and other coagulase negative Staphylococci and its validation by molecular methods.

Coagulase-negative staphylococci (CoNS) have been increasingly recognized as a clinically important group of species that can cause several opportunistic nosocomial infections. There are at least 47 known species of Staphylococci and to differentiate all these species >40 biochemical tests need to be performed. The present study was able to refine the CoNS identification process by using only five tests to identify S. epidermidis from the rest and used six other tests to identify eleven other clinically significant CoNS species. A total of 242 CoNS isolates were collected from tertiary care hospitals and included in the study. The five-biochemical test scheme devised based on mathematical probability derived from a computer algorithm included fermentation of mannitol, maltose, mannose, trehalose and novobiocin susceptibility to differentiate S. epidermidis from other CoNS species. The remaining CoNS isolates other than S. epidermidis were further characterized with the help of six additional tests, which identified another eleven species. Species-specific PCR and 16SrDNA sequencing were used to confirm and validate the identification scheme. Species-specific PCR and 16SrDNA sequencing showed 100% agreement with non-divergent phenotypic test results, indicating that the five selected assays are highly specific for identifying S. epidermidis. In conclusion, this study used only 11 tests to identify most of the clinically significant CoNS that can reduce cost and time. This scheme is easy to perform in any laboratory with basic resources, the results of this study were validated using more accurate molecular methods such as PCR and 16S rDNA typing to confirm the utility of the proposed scheme.

Endophthalmitis after intravitreal injections. Incidence, management and prognosis. / Endoftalmitis tras inyecciones intravítreas. Incidencia, manejo y pronóstico.

OBJECTIVE: To assess the rate of endophthalmitis after intravitreal injection (IVI) in a «clean room¼ of a single health centre, following the guidelines of the Spanish Vitreo-Retinal Society (SERV). An analysis was performed on the culture specimens, response to treatment, and final outcomes (guidelines). MATERIAL AND METHODS: A retrospective, observational study was conducted on a consecutive case series of patients diagnosed with infectious endophthalmitis after IVI in a single health centre between 2010 and 2015. Intravitreal and systemic treatment was given following the SERV guidelines. The patients were followed up the case was resolved. RESULTS: There were 5 cases of endophthalmitis out of 9467 IVI (incidence 0.053%). Positive cultures were obtained in aqueous and/or vitreous fluid in all cases, with Staphylococcus epidermidis being involved in 4 out of 5 cases. In 2 cases, final visual acuity was non-light perception due to intractable retinal detachments after resolution of the infectious process. CONCLUSIONS: IVI performed in a «clean room¼ have a low incidence of endophthalmitis. The most common infectious agent was Staphylococcus species. In 2 cases the functional prognosis was poor.

Electromechanical cell lysis using a portable audio device: enabling challenging sample preparation at the point-of-care.

Audio sources are ubiquitously available on portable electronic devices, including cell phones. Here we demonstrate lysis of Mycobacterium marinum and Staphylococcus epidermidis bacteria utilizing a portable audio device coupled with a simple and inexpensive electromagnetic coil. The resulting alternating magnetic field rotates a magnet in a tube with the sample and glass beads, lysing the cells and enabling sample preparation for these bacteria anywhere there is a cell phone, mp3 player, laptop, or other device with a headphone jack.

Incidence, management and outcomes of the first cfr-mediated linezolid-resistant Staphylococcus epidermidis outbreak in a tertiary referral centre in the Republic of Ireland.

AIM: To report the first Irish outbreak of cfr-mediated linezolid-resistant Staphylococcus epidermidis. METHODS: Linezolid-resistant S. epidermidis isolated at University Hospital Limerick from four blood cultures, one wound and four screening swabs (from nine patients) between April and June 2013 were characterized by pulsed-field gel electrophoresis (PFGE), multi-locus sequence typing (MLST) and staphylococcal cassette chromosome (SCCmec) typing. Antibiotic susceptibilities were determined according to the guidelines of the British Society for Antimicrobial Chemotherapy. The outbreak was controlled through prohibiting prescription and use of linezolid, adherence to infection prevention and control practices, enhanced environmental cleaning, isolation of affected patients, and hospital-wide education programmes. FINDINGS: PFGE showed that all nine isolates represented a single clonal strain. MLST showed that they belonged to ST2, and SCCmec typing showed that they encoded a variant of SCCmecIII. All nine isolates were cfr positive, and eight isolates were positive for the G2576T 23S rRNA mutation commonly associated with linezolid resistance. Isolates exhibited multiple antibiotic resistances (i.e. linezolid, gentamicin, methicillin, clindamycin, ciprofloxacin, fusidic acid and rifampicin). The adopted infection prevention intervention was effective, and the outbreak was limited to the affected intensive care unit. CONCLUSIONS: This is the first documented outbreak of cfr-mediated linezolid-resistant S. epidermidis in the Republic of Ireland. Despite this, and due to existing outbreak management protocols, the responsible micro-organism and source were identified efficiently. However, it became apparent that staff knowledge of antimicrobial susceptibilities and appropriate hygiene practices were suboptimal at the time of the outbreak, and that educational interventions (and re-inforcement) are necessary to avoid occurrence of antimicrobial resistance and outbreaks such as reported here.

INNOVATIVE MULTIPLANAR RECONSTRUCTION AND VOLUME-RENDERED COMPUTED TOMOGRAPHY IN THE ASSESSMENT OF SCLERAL BUCKLE-RELATED COMPLICATIONS.

PURPOSE: To describe the role of multiplanar reconstruction and three-dimensional volume-rendered imaging in the assessment of silicon-based scleral buckle (SB)-related complications. METHODS: Five eyes of five patients with SB-related complications where the history, surgical notes, and clinical examination proved inconclusive were included. Unenhanced axial orbital computed tomography images of all patients were acquired parallel to orbitomeatal line, and images were reviewed in orthogonal planes. The volume rendition of the imaged volume was evaluated in various tilts, with special reference to the spatial relationship of the band-buckle to the globe and bony orbit. All patients underwent imaging-assisted SB removal. RESULTS: Imaging assisted in in vivo localization of the obscure band or buckle in all five eyes. Band was seen as hyperdense structure encircling whole of the globe, whereas buckle was seen as segmental, broad, hyperdense structure with scleral indentation. Presence of SB was identified in three patients, and globe integrity was shown in the other two. Abnormal anterior displacement of band and buckle was demonstrated in three cases on volume-rendered imaging in relation to lateral orbital rim. Focal exuberant soft-tissue proliferation around the buckle was present in all patients, suggesting chronic inflammation and infection. Successful removal of band and buckle could be achieved, and all patients were relieved of their preoperative complaints. No complication occurred during intraoperative and postoperative period. CONCLUSION: Use of multiplanar reconstruction and three-dimensional volume-rendered computed tomography imaging played a pivotal role in surgical success.

A microbiological assessment of the oral hygiene of 24-72-month-old kindergarten children and disinfection of their toothbrushes.

BACKGROUND: The objective of this study is to assess the index of decayed, missing and filled teeth (DMF-T), habit of brushing teeth, and the microbiological agents accumulating on the children's toothbrushes for 4 weeks and response of these agents to disinfection via a chlorhexidine solution, then compare those results with the education and income levels of the children's parents. METHOD: Included in the study were 187 children (96 in the control group and 91 in the experiment group - chlorhexidine) chosen randomly from 600 kindergarten children whose ages ranged from 24 months to 72 months. The children selected had not taken any antibiotics, antimicotics for three months and dental treatments during this trial. The distribution of these children to the groups was also done randomly. After performing a survey for the education, occupation, and income status of the parents, the children were examined and the number of decayed teeth was recorded. The children were given toothbrushes, toothpaste (with fluroide), and the solutions (including distilled water and chlorhexidine) for four weeks under the condition that toothbrushes were returned at the end of each week. The 14 different microbiological agents observed as a result of the assessment of the samples taken in the first week were also included in the assessments of the samples taken over the four-week period. RESULTS: The decrease in the DMF-T index was found to be meaningful according to the differences in education, income, and occupation status of the parents. Of all the samples taken from the toothbrushes, the bacteria with the greatest rate of reproduction included Streptococcus mutans, Escherichia Coli, Pseudomonas aeuroginosa, Enterococcus spp, Staphylococcus epidermidis and Candida albicans. Except for Candida albicans, the other microorganisms taken as samples from the toothbrushes reproduced less overall. In the group using the solution with chlorhexidine, a meaningful decrease in bacterial reproduction was discovered compared to the control group. CONCLUSION: The findings of this study show that the education, occupation, and socioeconomic situations of the parents should be considered when discussing children's oral and dental health. Moreover, the study shows that disinfection of toothbrushes in order to prevent reinfection and contamination oral flora with the bacteria again is important in terms of preventive medicine and family-children health.

An in vitro study assessing the infection risk of low-cost polyethylene mosquito net compared with commercial hernia prosthetics.

BACKGROUND: The innovative use of sterilized mosquito net as a cheaper alternative to commercial mesh for hernia repair has gained increasing recognition. Developing health care systems have inherently higher surgical site infection rates, and concerns regarding the introduction of untested prosthetic hernia meshes have been raised. This in vitro study assesses the infection risk of polyethylene (PE) mosquito net mesh compared with commercial hernia prosthetics by assessing the essential (first) step in the pathogenesis of mesh infections. MATERIALS AND METHODS: Individual meshes were inoculated with Staphylococcusepidermidis and Staphylococcusaureus with a bacterial inoculum of 10(2) bacteria. Inoculated meshes were incubated for 18 h in tryptone soy broth and then analyzed using scanning electron microcopy. The final fraction of the bacteria adherent to each of the meshes was compared. One-way analysis of variance was performed on the bacterial counts. The Tukey test was used to determine the difference between the different biomaterials in the event the one-way analysis of variance was significant. RESULTS: There was no significant difference in the mean number of adherent bacteria to PE mosquito net compared with the monofilament polypropylene-based meshes (Prolene and Bard Soft Mesh). Multifilament Vypro mesh had significantly greater mean bacterial adherence compared with PE mosquito net (P < 0.001 with S aureus and P = 0.003 with S epidermidis). CONCLUSIONS: In vitro infection risk of PE mosquito net is not significantly different from commonly used monofilament polypropylene commercial prosthetics and is in fact lower than a commonly used commercial multifilament mesh. This study adds to the growing body of evidence that indicates that these meshes can be safely deployed.

Culture-based detection of methicillin-resistant Staphylococcus aureus by a network of European laboratories: an external quality assessment study.

Twenty-three hospital laboratories from Europe and Israel participated in an external quality assessment (EQA) of the culture-based detection of methicillin-resistant Staphylococcus aureus (MRSA). Participants also reported the MRSA prevalence in clinical cultures and patient screening specimens, as well as the MRSA screening practices employed at their hospitals. An EQA panel of 18 samples consisting of two MRSA harbouring SCCmec IV and I, and one strain each of methicillin-resistant coagulase-negative S. epidermidis, methicillin-sensitive S. aureus and Escherichia coli as pure strains or in mixtures at 10(7)-1 cfu absolute loads was analysed by the 23 participants. Seventeen (74%) participants identified 17 or more samples correctly. Of these, 15 (88%) utilised a chromogenic medium alone (ChromID, bioMérieux; BBL CHROMagar, BD Diagnostics; MRSA Select, Bio-Rad Laboratories) or combined with a conventional medium and up to three confirmatory tests. Proportions of MRSA among S. aureus isolated from clinical cultures varied widely, even among hospitals within countries, ranging from 11-20% to 61-70%. MRSA carriage rates were less variable (0-20%) between countries. Almost all participants (n=22, 96%) screened patients for MRSA carriage during 2009-2010, of which 15 (68%) screened intensive care unit (ICU) patients alone or combined with other targeted high-risk groups, and 10 (45%) combined nasal screening with another body site.

Assessment of linezolid resistance mechanisms among Staphylococcus epidermidis causing bacteraemia in Rome, Italy.

OBJECTIVES: To characterize linezolid resistance among blood cultured Staphylococcus epidermidis from patients at the Polyclinic Agostino Gemelli (2006-08). Isolates also showed elevated MICs of macrolide, lincosamide and streptogramin (MLS) compounds, which were investigated. METHODS: Ten S. epidermidis exhibiting linezolid MICs ≥ 4 mg/L were included. Isolates were screened for cfr mutations in 23S rRNA, L3, L4 and L22, and MLS genes by PCR/sequencing. Ribosomal proteins were compared with those from a linezolid-susceptible (MIC, 1 mg/L) clinical strain and ATCC 12228. cfr location was determined by Southern blot/hybridization. The cfr strain was submitted to plasmid curing. Epidemiology was assessed by PFGE and multilocus sequence typing (MLST). RESULTS: S. epidermidis displayed linezolid MICs of 4 or 8 mg/L, except for strain 4303A (MIC, 64 mg/L). These organisms and a linezolid-susceptible strain exhibited L3 Leu101Val compared with ATCC 12228. Isolates also showed L3 Phe147Leu and Ala157Arg, and L4 Asn158Ser. Strain 12375A possessed L4 Lys68Arg. Isolates were wild-type for 23S rRNA and L22. cfr was plasmid located in strain 4303A and the plasmid-cured strain exhibited a linezolid MIC (4 mg/L) similar to that for cfr-negative strains (4-8 mg/L). All organisms harboured erm(A) and msr(A), while vga(A) was detected in several isolates. All isolates were clonally related and ST-23. CONCLUSIONS: L3 Phe147Leu and/or Ala157Arg appeared responsible for the elevated linezolid MIC, since adjacent alterations have been associated with resistance. L4 Asn158Ser has been reported in a linezolid-susceptible isolate and Lys68Arg detected here did not seem to provide an additive effect. Acquisition of cfr markedly increased (8- to 16-fold) the linezolid MICs. vga(A) was associated with higher MICs of quinupristin/dalfopristin and retapamulin.

Periprosthetic joint infection: the economic impact of methicillin-resistant infections.

The orthopedic community has begun to witness a worrisome rise in the incidence of periprosthetic joint infections (PJIs) caused by resistant organisms. Besides other challenges associated with treating these infections, it appears that these infections may pose a higher cost compared to infections caused by sensitive organisms. Significantly higher cost of care for treatment of infections due to methicillin-resistant organisms were seen at a mean of $107,264 per case compared to $68,053 for treating PJI caused by sensitive strains (P < .0001). More effective strategies for preventing the spread of infections caused by resistant organisms need to be implemented to ease the social and economic strains facing the orthopedic community due to resistant organisms.

Evaluation of the effectiveness of commercially available contact plates for monitoring microbial environments.

AIM: The aim of this study was to measure the efficiency of contact plates to recover microbial contaminants from stainless steel surface. MATERIALS AND METHODS: Three commercially available contact plates were used to recover two biological indicators from stainless steel sheets. The method used was standardised and validated to provide robust results. Parameters such as wetness, fertility and loss of water were also investigated for possible correlation with recovery efficiency. RESULTS: The percentage of recovery from the contact plates was low and differences in recovery efficiency between brands depended upon the test organism. The poor recovery was probably due to the inability of the dried micro-organism to transfer to the plate, rather than the inability of the plate to grow the micro-organism. Wetness might help in improving recovery. CONCLUSIONS: The use of a validated protocol allowed robust investigations into the recovery efficiency of contact plates. SIGNIFICANCE AND IMPACT OF THE STUDY: The poor and variable recovery rates are of concern as they cast doubt on the comparability and reliability of environmental monitoring results where different commercial contact plates have been used.

PCR-DGGE assessment of the bacterial diversity of breast milk in women with lactational infectious mastitis.

BACKGROUND: Infectious mastitis is a common condition during lactation and in fact, represents one of the main causes leading to a precocious weaning. The number of studies dealing with lactational mastitis is low and, up to now, the etiological diagnosis is frequently made on the basis of unspecific clinical signs. The aim of this study was to investigate the microbial diversity of breast milk in 20 women with lactational mastitis employing culture-dependent and culture-independent (PCR-DGGE) approaches. METHODS: Breast milk samples were cultured in different media to investigate the presence of bacteria and/or yeasts, and a total of 149 representative isolates were identified to the species level by 16S rRNA gene PCR sequencing. The microorganisms recovered were compared with those found by PCR-DGGE analysis. To identify the DGGE profiles two reference markers of different microbial species were constructed. Sequence analysis of unknown bands was also performed. RESULTS: Staphylococci were the dominant bacterial group and Staphylococcus epidermidis was the dominant species. In a lower number of samples, other bacteria (mainly streptococci and a few gram-negative species) were also identified. Globally, PCR-DGGE results showed a good correlation with those obtained by culture-based methods. However, although DNA bands corresponding to different lactic acid bacteria were detected, such bacteria could not be isolated from the milk samples. CONCLUSION: Staphylococci seem to be the main etiological agents of human lactational mastitis. The combined use of culture and molecular techniques allowed a better characterization of the bacterial diversity in milk from women suffering from infectious mastitis. Our results suggest that this condition could be the result of a disbiotic process where some of the bacterial species usually present in human milk outgrow (staphylococci) while others disappear (lactobacilli or lactococci).

Healthcare costs associated with hemodialysis catheter-related infections: a single-center experience.

In patients undergoing hemodialysis, catheter-related bacteremia results in expensive hospitalizations. In our study, the mean cost was $23,451 per hospitalization. When itemized, housing ("bed-related") costs accounted for 66% of the total; laboratory costs accounted for 4%, radiologic costs accounted for 9%, and procedure-related costs accounted for 21%. Hypoalbuminemia and bacteremia due to methicillin-resistant Staphylococcus aureus (MRSA) are associated with higher healthcare costs; bacteremia due to MRSA is also associated with poor survival rates.

Assessment of bacterial contamination of three multidose ophthalmic solutions.

OBJECTIVE: To investigate the frequency of bacterial contamination of multidose proparacaine hydrochloride, tropicamide, and eyewash bottles used in veterinary ophthalmology examination rooms during normal operating procedures. METHODS: Three representative bottles each of proparacaine hydrochloride, tropicamide, and purified water eye wash were opened at the same time, numbered, and placed into small animal examination rooms. Doctors, students and technicians who were using the solutions were blinded to the study. Aerobic cultures were obtained at the time of opening (time 0), at 1 week (time 1), and at 2 weeks after opening (time 2) the bottles. The sites cultured included a drop of each solution, the inside of the bottle cap, the tip of the bottle, and the bottle threads and medication residue found in these threads. RESULTS: Aerobic cultures of tropicamide and proparacaine had no growth of bacteria from any of the evaluated sites. Staphylococcus epidermidis was cultured from the tip of one bottle of eye wash after 1 week. CONCLUSIONS: We conclude that proparacaine, tropicamide, and eyewash solutions used in veterinary examination rooms are adequately preserved for use in ophthalmic examination. They have a low level of bacterial contamination 1 or 2 weeks after opening when used and stored according to the recommendations of the product manufacturers and previous studies.

A comparison of four different microleakage tests for assessment of leakage of root canal fillings.

OBJECTIVE: The purpose of this study was to compare four different microleakage tests (dye leakage, electrochemical test, bacterial test and fluid filtration) for evaluation of the coronal seal of teeth obturated using Thermafil or lateral condensation techniques. STUDY DESIGN: One hundred forty-four extracted single-rooted teeth were selected and prepared. The specimens were divided into 8 experimental groups. In 4 groups the root canals were filled with Thermafil obturators and in the other 4 groups by the lateral condensation technique. Coronal microleakage was assessed after exposing one group of specimens (n = 15 teeth) from each of the obturation techniques to each of the four microleakage tests. RESULTS: In the fluid filtration test, lateral condensation showed statistically less leakage than the Thermafil technique (P < .05). Electrochemical and dye leakage test results showed no difference between the two obturation techniques (P < .05). However, in the bacterial leakage test, Thermafil showed less leakage than lateral condensation (P < .05). CONCLUSION: There is poor correlation between various methods to evaluate hydraulic leakage. The clinical significance of leakage tests in vitro is questionable.

Infection assessment of totally implanted long-term venous access devices.

AIM: Comparison of catheter tip versus port content culture techniques to assess infection in totally implanted vascular access devices (TIVAD). MATERIALS AND METHODS: Comparison of pocket swab, catheter-tip and port content cultures after removing the silicon puncture septum in a prospectively collected consecutive series of 102 TIVAD removed for clinical suspicion of infection, between May 2000 and March 2003. RESULTS: 102 totally implanted port-catheters in 98 patients, age ranging from 1 to 90 years (median 53 years), were removed 7 to 2616 days after insertion (median 210 days). Infection of the pocket surrounding the port was found in 21 cases, all proven by a positive culture of the pocket swab. Out of the remaining 81 cases without pocket infection, 32 had only a positive catheter tip culture, whereas 56 had a positive port content culture (p = 0.0002). Always the same microorganism was isolated in the 32 patients with positive catheter tip and port content cultures. The main organisms identified within TIVAD were Coagulase Negative Staphylococcus (CNS) (41 cases) and Candida sp (15 cases). Eight out of the 21 pocket infections were caused by Staphylococcus aureus. CONCLUSION: In the presence of local signs of infection, taking cultures of the pocket surrounding the port is sufficient for diagnostic purposes. When infection is localized within the device only, port content cultures taken after removal of the silicon septum are more often positive than cultures of the catheter tip, and constitute therefore a more reliable tool for the assessment of TIVAD infection.

Assessment of ica operon carriage and biofilm production in Staphylococcus epidermidis isolates causing bacteraemia in bone marrow transplant recipients.

The clinical significance of coagulase-negative staphylococci isolated from blood culture is typically assessed on the basis of a combination of clinical and microbiological criteria. However, these criteria are difficult to apply to haematology patients who are highly immunosuppressed and from whom blood cultures are obtained most frequently through a central venous catheter. This study analysed 112 episodes of Staphylococcus epidermidis bacteraemia that occurred in 79 bone marrow transplant recipients. In 73 (65%) episodes, only one blood culture set was positive for S. epidermidis, while 39 (35%) episodes grew S. epidermidis from multiple blood cultures. Nine patients had two or more episodes of bacteraemia with the same strain, as determined by pulsed-field gel electrophoresis (PFGE). The PFGE method also showed that 34 (31%) isolates belonged to seven clusters, indicating the persistence of certain clones in the environment. Of the 109 isolates analysed, 59 (54%) produced biofilm and 91 (83.5%) carried the ica operon. Isolates that produced biofilm were observed to colonise central venous catheters faster than non-biofilm-producing isolates (18 vs. 37 days; p 0.03). No clinical features were associated with carriage of the ica operon, but the ica operon was carried more frequently by the isolates that formed clusters.