A comprehensive review of microbial contamination in the indoor environment: sources, sampling, health risks, and mitigation strategies

The quality of the indoor environment significantly impacts human health and productivity, especially given the amount of time individuals spend indoors globally. While chemical pollutants have been a focus of indoor air quality research, microbial contaminants also have a significant bearing on indoor air quality. This review provides a comprehensive overview of microbial contamination in built environments, covering sources, sampling strategies, and analysis methods. Microbial contamination has various origins, including human occupants, pets, and the outdoor environment. Sampling strategies for indoor microbial contamination include air, surface, and dust sampling, and various analysis methods are used to assess microbial diversity and complexity in indoor environments. The review also discusses the health risks associated with microbial contaminants, including bacteria, fungi, and viruses, and their products in indoor air, highlighting the need for evidence-based studies that can relate to specific health conditions. The importance of indoor air quality is emphasized from the perspective of the COVID-19 pandemic. A section of the review highlights the knowledge gap related to microbiological burden in indoor environments in developing countries, using India as a representative example. Finally, potential mitigation strategies to improve microbiological indoor air quality are briefly reviewed.

An In Vitro and In Vivo Study of the Efficacy and Toxicity of Plant-Extract-Derived Silver Nanoparticles

Silver nanoparticles (AgNPs) display unique plasmonic and antimicrobial properties, enabling them to be helpful in various industrial and consumer products. However, previous studies showed that the commercially acquired silver nanoparticles exhibit toxicity even in small doses. Hence, it was imperative to determine suitable synthesis techniques that are the most economical and least toxic to the environment and biological entities. Silver nanoparticles were synthesized using plant extracts and their physico-chemical properties were studied. A time-dependent in vitro study using HEK-293 cells and a dose-dependent in vivo study using a Drosophila model helped us to determine the correct synthesis routes. Through biological analyses, we found that silver nanoparticles’ cytotoxicity and wound-healing capacity depended on size, shape, and colloidal stability. Interestingly, we observed that out of all the synthesized AgNPs, the ones derived from the turmeric extract displayed excellent wound-healing capacity in the in vitro study. Furthermore, the same NPs exhibited the least toxic effects in an in vivo study of ingestion of these NPs enriched food in Drosophila, which showed no climbing disability in flies, even at a very high dose (250 mg/L) for 10 days. We propose that stabilizing agents played a superior role in establishing the bio-interaction of nanoparticles. Our study reported here verified that turmeric-extract-derived AgNPs displayed biocompatibility while exhibiting the least cytotoxicity.

Comparison of Five Different Irrigation Techniques on Smear Layer Removal in Apical Thirds of Root Canals of Mandibular First Premolar: A Scanning Electron Microscopic Study

Aim:

This study was conducted to compare smear layer removal by five different irrigation techniques—conventional needle irrigation (CI), manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and negative apical pressure (NAP).

Materials and Methods:

Fifty freshly extracted mandibular first premolars were cleaned and shaped by One Curve rotary files and 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. The samples were divided into five equal groups (n = 10), according to the final irrigation activation technique: Group I, CI; Group II, MDA; Group III, PUI; Group IV, SI; and Group V, NAP. The samples were prepared and observed under a scanning electron microscope. The photomicrographs were recorded and evaluated with a scoring system.

Results:

Group I and Group II had the highest scores, which showed a statistically significant difference between the other groups (P < 0.05). This was followed by PUI, NAP, and SI.

Conclusion:

Final irrigation activation with SI and NAP resulted in the better removal of smear layer when compared to that with other groups.

Ultrasound-Accelerated Amide Coupling Reactions Directed toward the Synthesis of 1-Acetyl-3-carboxamide-β-carboline Derivatives of Biological Importance

Several biologically important 1-acetyl-3-carboxamide-β-carboline derivatives were rapidly synthesized by ultrasound-promoted amide coupling of 1-acetyl-9H-pyrido[3,4-b]indole-3-carboxylic acid with substituted aromatic amines. The major advantages of the proposed method are that use of ultrasound irradiations afforded the desired products in a drastically reduced reaction time and in excellent yields compared with conventional stirring.

Detection of Yersinia enterocolitica in food: an overview

Yersinia enterocolitica is a gastrointestinal pathogen which causes yersiniosis, an illness characterized by diarrhea, ileitis, and mesenteric lymphadenitis. Y. enterocolitica is transmitted via the feco-oral route by the consumption of contaminated food or water. Several phenotypic and genotypic methods have been developed to reliably detect Y. enterocolitica in food. However, the source of infection of many recently reported foodborne outbreaks remains obscure. The detection of this pathogen in food is a challenging task, since it shares similarities with other enteric bacteria. The presence of other microorganisms in the food samples makes it even more difficult to identify this slow-growing pathogen. Therefore, the present-day emphasis is on the development of sensitive, easily automated methods suitable for in-situ detection, allowing quick and cost-effective characterization of food samples. This review summarizes and compares the currently available cultural, immunological, and molecular methods, particularly in relation to their specific merits or demerits when implemented for the detection of Y. enterocolitica in food.

Prospective phase II study of chemoembolization with drug-eluting beads for hepatic neuroendocrine metastases: Interim analysis

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Background: To evaluate safety and efficacy of transarterial chemoembolization with doxorubicin eluting beads (DEB-TACE) in 30 patients with hepatic neuroendocrine metastases (NET) in a prospective phase II study. We report the interim analysis on 10 patients.

Methods: Patients who met inclusion criteria (NET liver-dominant metastases, ECOG 0-1, treatment naïve) underwent up to 4 DEB-TACE sessions (100-300 micron beads loaded with up to 100mg of doxorubicin) within a 6-month period. Statistical plan included interim analysis of initial 10 patients to assess therapeutic efficacy (defined as objective response≥50%). Tumor response was assessed by MR imaging 1 month after treatment using contrast-enhancement (EASL) and tumor size (RECIST). Safety was assessed by NCI Common Terminology Criteria.

Results: DEB-TACE was successfully performed in 10 patients (22 targeted lesions). Patient characteristics included mean age 65 yrs; ECOG 0/1 (6/4); carcinoid syndrome (n=2); tumor burden range (4-75%), and mean targeted tumor size 4.8 cm (range 1.2-10.2). At one month follow-up (n=9), Grade 3 toxicities consisted of hyperglycemia (n=3), abdominal pain (n=3), fatigue (n=1), biloma (n=1) and elevated ALT (n=1). Note that four patients had Grade 2 bilomas, which occurred in the setting of small lesions (<2cm), diffuse disease with very low tumor burden (near military pattern), and single lesion ≥ 5cm. Tumor response using MR imaging at 1 month-follow-up revealed a mean treated tumor decrease in size of 7% (p=0.03), and a mean decrease in contrast-enhancement of 59% (p<0.0001). Using RECIST, partial response was achieved in 1 patient (11%), whereas 8 patients (89%) had stable disease. Using EASL criteria, 7 patients (78%) had objective tumor response and 2 (12%) had stable disease.

Conclusions: Interim analysis shows therapeutic efficacy of DEB-TACE in liver-dominant NET metastases. Early recommendation suggests DEB-TACE may be best suited for NET patients with multifocal disease or diffuse disease with large tumor burden.

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No significant financial relationships to disclose.

Molecular and biochemical characterization of urease and survival of Yersinia enterocolitica biovar 1A in acidic pH in vitro

Background

Yersinia enterocolitica, an important food- and water-borne enteric pathogen is represented by six biovars viz. 1A, 1B, 2, 3, 4 and 5. Despite the lack of recognized virulence determinants, some biovar 1A strains have been reported to produce disease symptoms resembling that produced by known pathogenic biovars (1B, 2-5). It is therefore imperative to identify determinants that might contribute to the pathogenicity of Y. enterocolitica biovar 1A strains. Y. enterocolitica invariably produces urease and the role of this enzyme in the virulence of biovar 1B and biovar 4 strains has been reported recently. The objective of this work was to study genetic organization of the urease (ure) gene complex of Y. enterocolitica biovar 1A, biochemical characterization of the urease, and the survival of these strains under acidic conditions in vitro.

Results

The ure gene complex (ureABCEFGD) of Y. enterocolitica biovar 1A included three structural and four accessory genes, which were contiguous and was flanked by a urea transport (yut) gene on the 3' side. Differences were identified in ure gene complex of biovar 1A strain compared to biovar 1B and 4 strains. This included a smaller ureB gene and larger intergenic regions between the structural genes. The crude urease preparation exhibited optimal pH and temperature of 5.5 and 65°C respectively, and Michaelis-Menten kinetics with a K_m of 1.7 ± 0.4 mM urea and V_max of 7.29 ± 0.42 μmol of ammonia released/min/mg protein. The urease activity was dependent on growth temperature and growth phase of Y. enterocolitica biovar 1A, and the presence of nickel in the medium. The molecular mass of the enzyme was > 545 kDa and an isoelectric point of 5.2. The number of viable Y. enterocolitica biovar 1A decreased significantly when incubated at pH 2.5 for 2 h. However, no such decrease was observed at this pH in the presence of urea.

Conclusions

The ure gene cluster of biovar 1A strains though similar to biovar 1B and 4 strains, exhibited important differences. The study also showed the ability of biovar 1A strains of Y. enterocolitica to survive at highly acidic pH in vitro in the presence of urea.

Distribution of virulence-associated genes inYersinia enterocoliticabiovar 1A correlates with clonal groups and not the source of isolation

Yersinia enterocolitica, an important food- and water-borne enteric pathogen, is represented by six biovars viz. 1A, 1B and 2-5. Some biovar 1A strains, despite lacking virulence plasmid (pYV) and chromosomal virulence genes, have been reported to cause symptoms similar to that produced by isolates belonging to known pathogenic biovars. Virulence-associated genes viz. ail, virF, inv, myfA, ystA, ystB, ystC, tccC, hreP, fepA, fepD, fes, ymoA and sat were studied in 81 clinical and nonclinical strains of Y. enterocolitica biovar 1A by PCR amplification. All strains lacked ail, virF, ystA and ystC genes. The distribution of other genes with respect to clonal groups revealed that four genes viz. ystB, hreP, myfA and sat were associated exclusively with strains belonging to clonal group A. The clonal groups A and B were differentiated previously based on rep (REP-/ERIC) - PCR genomic fingerprinting. The distribution of virulence-associated genes, however, did not differ significantly between clinical and nonclinical strains. In strains of Y. enterocolitica biovar 1A, clonal groups seem to reflect virulence potential better than the source (clinical vs. nonclinical) of isolation.

Use of viscodissection and silicone oil in vitrectomy for severe diabetic retinopathy

Improvement in surgical techniques has led to improved anatomic and functional success rates following surgery for severe complications of proliferative diabetic retinopathy (PDR). We compared the anatomic and functional outcomes of surgery in a non-randomized, consecutive case series of patients with severe PDR. We found that viscodissection using Healon provides outcomes comparable to conventional pick and scissors dissection. We also found that adjunctive use of silicone oil can salvage selected cases with particularly severe manifestations of PDR (e.g., the fibrinoid syndrome). With proper selection of patients and techniques, the anatomic success rate can exceed 80% even in the most severe cases. The goal of this paper is to show the applicability of using viscodissection and silicone oil infusion during vitrectomy in eyes with severe PDR.

Vitrectomy with silicone oil infusion in severe diabetic retinopathy

AIMS

To determine the results of pars plana vitrectomy (PPV) and silicone oil infusion (SOI) in severe proliferative diabetic retinopathy (PDR).

METHODS

The records of 23 eyes (21 patients: 12 males, nine females) with PDR who had undergone PPV and SOI were reviewed retrospectively.

RESULTS

Average follow up was 5.4 months (range 1-25). Surgical indications were tractional retinal detachment (TRD) (17.4%), traction-rhegmatogenous retinal detachment (TRRD) (8.7%), TRD with vitreous haemorrhage (VH) (48%), TRD with neovascular glaucoma (NVG) (8.6%), TRD with fibrinoid syndrome (FS) (17.3%). With one operation, the retinal reattachment rate was 17/23 (74%). Among these 23 eyes, 11 (48%) had previously failed vitrectomy, and the retina was attached in 8/11 (73%) with a single procedure. With additional surgery employing PPV and SOI, the final reattachment rate was 20/23 (87%). The only cases with intraocular pressure <5 mm Hg had retinal detachment. Postoperative visual acuity (VA) improved in 10 eyes (44%), was unchanged in three (12%), and decreased in 10 eyes (44%).

CONCLUSION

SO tamponade is useful in severely diseased eyes with PDR, even in the presence of rubeosis iridis (RI) and NVG, FS, or in cases with previously failed vitrectomy, especially in the presence of RI.

Exudative retinal detachment in relapsing polychondritis : case report and literature review

OBJECTIVE

To report the atypical ocular symptoms (arterialized conjunctival vessels, exudative retinal detachment) that can be the presenting manifestations of relapsing polychondritis.

DESIGN

Observational case report and literature review.

METHODS

A complete ocular and systemic evaluation was performed on a patient with relapsing polychondritis and exudative retinal detachment.

MAIN OUTCOME MEASURES

Retinal, choroidal, and scleral findings.

RESULTS

A 73-year-old man with relapsing polychondritis presented with a unilateral large bullous exudative retinal detachment and marked choroidal and scleral thickening bilaterally.

CONCLUSIONS

Ophthalmologists should consider relapsing polychondritis in the differential diagnosis of exudative retinal detachment. A combination of echographic and laboratory findings can assist in the accurate diagnosis of this rare condition.

Rifabutin-associated hypopyon uveitis in human immunodeficiency virus-negative immunocompetent individuals

OBJECTIVE

To report the occurrence of rifabutin-associated hypopyon uveitis in human immunodeficiency virus (HIV)-negative immunocompetent individuals.

DESIGN

Retrospective case series.

PARTICIPANTS

Three HIV-negative subjects on rifabutin and clarithromycin for Mycobacterium avium complex infections with hypopyon uveitis are described. One subject was iatrogenically immunosuppressed because of a prior lung transplant. Two subjects had no known immunosuppressive conditions.

INTERVENTION

Topical and regional steroid therapy. Discontinuation of rifabutin was required in two subjects.

MAIN OUTCOME MEASURES

Visual acuity, resolution of hypopyon, anterior uveitis, and vitreitis.

RESULTS

All subjects had resolution of hypopyon after therapy, two within 24 hours of beginning topical steroids. Vitreitis resolved with the discontinuation of rifabutin in two subjects. Chronic low-grade anterior uveitis and vitreitis were observed in the remaining subject, whose rifabutin dose was lowered but not discontinued because of active Mycobacterium avium complex osteomyelitis.

CONCLUSIONS

Rifabutin-associated uveitis is well described in HIV-positive individuals, but it has been reported only once in an HIV-negative individual. We report two cases of hypopyon uveitis in immunocompetent individuals and one case in an immunosuppressed HIV-negative individual. All three subjects were receiving concurrent rifabutin and clarithromycin. Awareness that this entity can occur in HIV negative and nonimmunosuppressed individuals and that it can mimic infectious endophthalmitis may spare the subject from an invasive workup of systemic infection.

Central retinal vein occlusion: report of two familial cases

The authors report a 46-year-old father and 17-year-old son who each presented with unilateral central retinal vein occlusion (CRVO) and bilateral abnormalities of retinal vascular perfusion. The son presented with a nonperfused CRVO in the left eye, developed traction-rhegmatogenous retinal detachment treated with vitreous surgery, and developed prolonged arteriovenous filling in the retina of the fellow eye. The father presented with progressive CRVO in the right eye, developed choroido-vitreal neovascularization following laser treatment to create a chorioretinal anastomosis, underwent vitrectomy for retinal detachment and vitreous hemorrhage in that eye, and developed prolonged arm-eye and retinal arteriovenous circulation times in the fellow eye. An extensive evaluation (including hematological studies and imaging of the major vessels of the neck) failed to reveal a predisposing cause in either patient although echocardiography disclosed a mitral valve thrombus in the father. After institution of coumadin therapy, the circulatory parameters in the fellow eye of each patient improved.

Central retinal vein occlusion: review of management

Central retinal vein occlusion is usually a disease of the elderly and is often associated with systemic vascular disease, e.g., hypertension, diabetes mellitus, arteriosclerotic vascular disease. Younger patients, especially those less than 45 years of age, with retinal vein occlusion should be evaluated carefully for the possibility of an underlying thrombotic tendency. The authors describe the ocular manifestations, pathogenesis, associated conditions, patient evaluation, and treatment of patients with central retinal vein occlusion.