Comparison of different concentrations of chlorhexidine-iodophor composite solution on human skin fibroblasts.

OBJECTIVE: Chlorhexidine-iodophor (CHX-IP) composite solution is a polymer of chlorhexidine and iodophor produced with new technology, for use in diabetic foot infection. However, the effect of CHX-IP on the growth activity of fibroblasts remains unknown, thus the effects of different concentrations of CHX-IP composite solution on the viability and micromorphology of human skin fibroblasts were studied in vitro cell culture in this study. METHOD: A cell viability assay was applied to calculate cell viability and an inverted fluorescence microscope was used to observe cell morphology over five days. RESULTS: The results showed that the toxic effect of CHX-IP on fibroblasts was solution concentration-dependent and decreased over time. When the concentration of CHX-IP was 5.0mg/ml, 2.5mg/ml, 0.625mg/ml, 0.15625mg/ml, 0.078125mg/ml or 0mg/ml, the difference of optical density (OD) value on different days was statistically significant (p<0.05). There were statistically significant differences in the OD value of fibroblasts among different concentrations of CHX-IP on: day 2 (F=4.809, p=0.004); day 3 (F=21.508, p<0.001); day 4 (F=63.952, p<0.001); and day 5 (F=160.407, p<0.001). In addition, a concentration of 5.0mg/ml CHX-IP resulted in a fibroblastic viability rate of 0% on day 4, when CHX-IP was diluted to 2.5mg/ml or 1.25 mg/ml, fibroblastic viability rate decreased to 0% day 5. However, when the CHX-IP was diluted to 0.15625mg/ml or 0.078125mg/ml, the fibroblastic cell viability rate increased slightly on day 5. The morphology of cells observed under microscope indirectly supported this result. CONCLUSION: The findings of this study showed that the toxic effect of CHX-IP on fibroblasts was solution concentration-dependent and decreased over time.

The effect and mechanism of iodophors on the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials.

BACKGROUND: Iodophors are known to be a treatment for biofilm-related periprosthetic joint infection. However, the efficacy and mechanism of eradicating biofilms from different artificial joint materials after iodophor treatment are unknown. This study was conducted to understand the effect and mechanism of iodophors with respect to the adhesion and virulence of Staphylococcus aureus biofilms attached to artificial joint materials. METHODS: Biofilms of Staphylococcus aureus strains were grown on titanium alloy, cobalt chromium molybdenum and polyethylene coupons, which are commonly used materials for artificial joints, for 24 h. Afterward, all coupons were divided into experimental and control groups: (1) exposed to a 0.5 ± 0.05% iodophor for 5 min and (2) exposed to phosphate-buffered saline for 5 min. To gauge the level of biofilm, colony forming units (CFU), live/dead staining confocal microscopy and crystal violet staining were used. Meanwhile, the expression of icaACDR and clfA, which are related to virulence and adhesion, was examined in both the experimental and control groups. RESULTS: A roughly three-log decrease in CFU/cm2 was seen in the viable plate count compared to the control group. Confocal imaging and crystal violet staining verified the CFU data. Moreover, the expression of icaACDR was reduced on three different orthopaedic implant materials, and the expression of clfA was also inhibited on titanium alloy coupons exposed to the iodophor. CONCLUSIONS: Our results indicated that exposure to an iodophor for 5 min could significantly eliminate biofilms. When Staphylococcus aureus that had adhered to these three materials, which were used for artificial joints, was treated with an iodophor for 5 min, the expression of icaACDR was significantly reduced. This provides strong evidence for clinically clearing periprosthetic joint infections without removing the artificial joints.

Effect of antibiotics and sanitizers on Salmonella biofilms associated with seafood contact surfaces.

This study investigates the effect of antibiotics and sanitizers on biofilm forming Salmonella isolated from different seafood contact surfaces. Four Salmonella were isolated from 384 swab samples collected from various contact surfaces of fishing boats, fish landing centres and seafood processing plants. One out of four isolates was from the fishing boat (FB I -1) other three isolates were from the seafood processing plant (FPPII -4, FPPII- 5, FPPI-3). The ability of Salmonella to form biofilms on different contact surfaces (HDPE, stainless steel, wood, glass, tiles) was tested with the microbial load on different incubation days, and a higher count was observed on day five. The effect of sanitizer viz., sodium hypochlorite (20, 50, 100, 200 mg/l) and iodophor (2, 5, 10 mg/l) on the biofilm formed on different seafood contact surfaces were investigated. A reduction of 2-3 log was observed on surfaces of HDPE and stainless steel when they were treated with a minimum of 5 mg/l of iodophor or 20 mg/l of sodium hypochlorite after a contact time of 5 min. Antibiotic resistance of biofilm forming Salmonella was tested for different classes of antibiotics (penicillin, ß-lactams, quinolones, macrolides, aminoglycosides, phenol drugs, sulfonamides, cephalosporin). All four isolates showed intermediate resistance to ciprofloxacin, a quinolone drug. Only one isolate FB I -1 (fishing boat deck) expressed resistance to more drugs, viz., ßlactams (AMC, AMP, penicillin G), macrolides (AZM) and nitrofurantoin (NIT). These findings shall help the seafood processors to mitigate the formation of Salmonella biofilms on various seafood contact surfaces with different sanitizers and the antibiotic resistance of biofilm forming Salmonella shall give knowledge on human clinical treatments. With this study, we shall recommend the regulatory authorities control the contamination level of fish handling areas.

Antidotal Potency of the Novel, Structurally Different Adsorbents in Rats Acutely Intoxicated with the T-2 Toxin.

In this paper, the potential antidote efficacy of commercially available formulations of various feed additives such as Minazel-Plus®, Mycosorb®, and Mycofix® was considered by recording their incidence on general health, body weight, and food and water intake, as well as through histopathology and semiquantitative analysis of gastric alterations in Wistar rats treated with the T-2 toxin in a single-dose regimen of 1.67 mg/kg p.o. (1 LD50) for 4 weeks. As an organic adsorbent, Mycosorb® successfully antagonized acute lethal incidence of the T-2 toxin (protective index (PI) = 2.25; p < 0.05 vs. T-2 toxin), and had adverse effects on body weight gain as well as food and water intake during the research (p < 0.001). However, the protective efficacy of the other two food additives was significantly lower (p < 0.05). Treatment with Mycosorb® significantly reduced the severity of gastric damage, which was not the case when the other two adsorbents were used. Our results suggest that Mycosorb® is a much better adsorbent for preventing the adverse impact of the T-2 toxin as well as its toxic metabolites compared with Minazel-plus® or Mycofix-plus®, and it almost completely suppresses its acute toxic effects and cytotoxic potential on the gastric epithelial, glandular, and vascular endothelial cells.

MmpL3 Inhibition: A New Approach to Treat Nontuberculous Mycobacterial Infections.

Outside of Mycobacterium tuberculosis and Mycobacterium leprae, nontuberculous mycobacteria (NTM) are environmental mycobacteria (>190 species) and are classified as slow- or rapid-growing mycobacteria. Infections caused by NTM show an increased incidence in immunocompromised patients and patients with underlying structural lung disease. The true global prevalence of NTM infections remains unknown because many countries do not require mandatory reporting of the infection. This is coupled with a challenging diagnosis and identification of the species. Current therapies for treatment of NTM infections require multidrug regimens for a minimum of 18 months and are associated with serious adverse reactions, infection relapse, and high reinfection rates, necessitating discovery of novel antimycobacterial agents. Robust drug discovery processes have discovered inhibitors targeting mycobacterial membrane protein large 3 (MmpL3), a protein responsible for translocating mycolic acids from the inner membrane to periplasm in the biosynthesis of the mycobacterial cell membrane. This review focuses on promising new chemical scaffolds that inhibit MmpL3 function and represent interesting and promising putative drug candidates for the treatment of NTM infections. Additionally, agents (FS-1, SMARt-420, C10) that promote reversion of drug resistance are also reviewed.

Can sterility of stripped iodophor-impregnated plastic adhesive drape be maintained at the time of incision closure in total hip arthroplasty?

OBJECTIVE: The aim of this study was to analyze the contamination rates of the skin under the iodophor-impregnated plastic adhesive drape (IOD) at the time of incision closure in total hip arthroplasty (THA). METHODS: A total of 225 patients undergoing primary THA (28 men, 197 women; mean age=65 years; age range=30-85) were included in this study. After asepsis using a solution of 1% chlorhexidine with 83% alcohol by volume, the surgical site was painted with a 10% povidone-iodine solution, and IOD was attached tautly at the start of surgery. Swabs of the surgical site were collected as follows: swab A from the skin before IOD application, swab B from the surface of the IOD at the time of incision closure, and swab C from the skin after peeling back the IOD. The obtained samples were promptly sent for microbiological analysis. The contamination rate was determined for swabs A, B, and C, and the contamination rate of swab C was compared with that of swabs A and B, and the bacterial species were identified. RESULTS: Positive cultures were seen in 8 cases (3.6%) for swab A, 10 cases (4.4%) for swab B, and 22 cases (9.8%) for swab C. The contamination rate of swab C was significantly higher than that of swabs A (p=0.008) and B (p=0.028). Coagulase-negative Staphylococcus (n=10) and Cutibacterium acnes (n=7) were the most frequently cultured microorganisms from swab C. CONCLUSION: In THA, the contamination rate of the skin after peeling off the IOD before incision closure was higher than that of the skin immediately after sterilization with povidone-iodine and higher than that on the IOD at the time of incision closure. The detected bacterial species were considered clinically significant pathogens. Preventive measures against infection, such as minimizing stripping of the IOD or re-sterilizing bare skin after IOD stripping, should be instituted in consideration of these findings when performing THA using IOD.

Efficacy of Cadexomer Iodine in the Treatment of Chronic Ulcers: A Randomized, Multicenter, Controlled Trial.

INTRODUCTION: Due to being hard to heal, chronic ulcers account for high morbidity. OBJECTIVE: This study compares the safety and efficacy of 2 formulations of cadexomer iodine and standard care for the treatment of chronic ulcers. MATERIALS AND METHODS: This prospective, randomized, open-label clinical trial was conducted at 8 cities across 15 institutions in India from March 2016 to March 2017. After screening a total of 145 patients with chronic, recalcitrant ulcers, 124 were randomized to 1 of 3 treatments: 0.9% cadexomer iodine ointment plus standard care (n = 41), 0.9% cadexomer iodine powder plus standard care (n = 43), and standard care alone (n = 40). All patients completed the maximum treatment period of 12 weeks, with the exception of 8 who discontinued during the study period. At the end of the treatment period, endpoints were assessed. RESULTS: The percentage of reduction in ulcer size from baseline to the primary endpoint of 12 weeks was significantly higher with both formulations of cadexomer iodine ointment (94.3% ± 10.6%) and powder (90.4% ± 14.9%) as compared with standard care alone (67.8% ± 21.8%). The percentage of patients with complete wound healing at the end of the 12 weeks was significantly higher in patients treated with both formulations of cadexomer iodine ointment (65.8%) and powder (58.1%) as compared with standard care alone (20.0%). CONCLUSIONS: These results demonstrate that cadexomer iodine, in comparison with standard care alone, increases the percentage of reduction in ulcer size and promotes complete wound healing in chronic ulcers.

Types of antiseptics, presentations and rules of use. / Tipos de antisépticos, presentaciones y normas de uso.

Antiseptics are chemical substances that when applied topically onto intact skin, mucous membranes or wounds partially or completely reduces the population of living microorganisms in those tissues. Different types of antiseptics are available - those most commonly used in clinical practice being alcohols, iodinated compounds and chlorhexidine. When using an antiseptic, consideration is required of its spectrum of antimicrobial activity, latency, residual effects, possible interferences of the presence of organic material with the activity of the antiseptic, its side effects, compatibility with other antiseptics, and cost. This article is part of a supplement entitled "Antisepsis in the critical patient", which is sponsored by Becton Dickinson.

Genomic Insight into Mechanisms of Reversion of Antibiotic Resistance in Multidrug Resistant Mycobacterium tuberculosis Induced by a Nanomolecular Iodine-Containing Complex FS-1.

Drug induced reversion of antibiotic resistance is a promising way to combat multidrug resistant infections. However, lacking knowledge of mechanisms of drug resistance reversion impedes employing this approach in medicinal therapies. Induction of antibiotic resistance reversion by a new anti-tuberculosis drug FS-1 has been reported. FS-1 was used in this work in combination with standard anti-tuberculosis antibiotics in an experiment on laboratory guinea pigs infected with an extensively drug resistant (XDR) strain Mycobacterium tuberculosis SCAID 187.0. During the experimental trial, genetic changes in the population were analyzed by sequencing of M. tuberculosis isolates followed by variant calling. In total 11 isolates obtained from different groups of infected animals at different stages of disease development and treatment were sequenced. It was found that despite the selective pressure of antibiotics, FS-1 caused a counter-selection of drug resistant variants that speeded up the recovery of the infected animals from XDR tuberculosis. Drug resistance mutations reported in the genome of the initial strain remained intact in more sensitive isolates obtained in this experiment. Variant calling in the sequenced genomes revealed that the drug resistance reversion could be associated with a general increase in genetic heterogeneity of the population of M. tuberculosis. Accumulation of mutations in PpsA and PpsE subunits of phenolpthiocerol polyketide synthase was observed in the isolates treated with FS-1 that may indicate an increase of persisting variants in the population. It was hypothesized that FS-1 caused an active counter-selection of drug resistant variants from the population by aggravating the cumulated fitness cost of the drug resistance mutations. Action of FS-1 on drug resistant bacteria exemplified the theoretically predicted induced synergy mechanism of drug resistance reversion. An experimental model to study the drug resistance reversion phenomenon is hereby introduced.

Estimating the Clinical Outcomes and Cost Differences Between Standard Care With and Without Cadexomer Iodine in the Management of Chronic Venous Leg Ulcers Using a Markov Model.

Chronic venous leg ulcers (VLUs) affect up to 1% of the adult population in the developed world and present a significant financial and resource burden to health care systems. Cadexomer iodine (CI) is an antimicrobial dressing indicated for use in chronic exuding wounds. The aim of this study was to estimate the cost utility of using CI + standard care (SC) - ie, high compression multicomponent bandaging including debridement - compared with SC alone in the management of chronic (>6 months' duration) VLUs from a payer's perspective. A Markov model was constructed to evaluate the cost and clinical benefits (healing and decreased infection rates) of the 2 treatment modalities over a 1-year period using data from 4 randomized, controlled clinical studies (RCTs) included in a recent Cochrane review and cost data from a recently published economic evaluation of VLUs. Costs were calculated using 2014 United States dollars; wound outcomes in- cluded complete healing in 212 patients reported in the Cochrane meta-analysis and quality-adjusted life years (QALYs), with utility values obtained from 200 patients with VLUs calculated using standard gamble. Treatment with CI over 1 year was $7,259 compared to $7,901 for SC. This resulted in a cost savings of $643/patient in favor of CI compared with SC. More patients treated with CI (61%) had their wounds healed compared to 54% treated with SC. Furthermore, patients treated with CI+SC experienced 6 additional ulcer-free weeks compared to persons treated with SC alone (ie, 25 ulcer- free weeks compared to 19 ulcer-free weeks, respectively). Overall, CI resulted in 0.03 more QALYs (ie, 0.86 QALYs compared to 0.83 for SC). The use of CI in addition to SC compared to SC alone over 52 weeks resulted in more wounds healed and more QALYs along with a decrease of overall costs The results of this study suggest CI is cost effective com- pared to SC alone in the management of patients with chronic VLUs. Prospective, controlled clinical studies are needed to elucidate the effect and cost effectiveness of CI on VLUs with and without signs of infection as compared to SC, other antiseptics, and more advanced topical treatment modalities.

[Impact of insertion timing of iodophor cotton ball on the control of infection complications after transrectal ultrasound guided prostate biopsy].

OBJECTIVE: To explore the impact of insertion timing of iodophor cotton ball on the control of infection complications after transrectal ultrasound (TRUS) guided prostate biopsy. METHODS: A total of 197 patients undergoing TRUS-guided prostate biopsy from March 2012 to January 2013 were randomly divided into post-discharge, pre-discharge and pre-discharge plus post-discharge groups. A prospective study was made on the symptoms of infections, signs and relevant laboratory examinations in all three groups. RESULTS: Infections occurred in 6/66 patients in the post-discharge group and 2 patients in the other two groups. The prevalence rates were 7.58%, 3.08% and 3.03% respectively. Statistically significant difference existed in the prevalence rate between pre-discharge and post-discharge groups (P < 0.05). Yet no statistically significant difference existed between pre-discharge and pre-discharge plus post-discharge groups (P > 0.05). CONCLUSION: During the TRUS guided prostate biopsy, inserting an iodophor cotton ball before placing an ultrasonic probe to the rectum can control the infection and reduce its prevalence rate.

The effect of various wound dressings on the activity of debriding enzymes.

OBJECTIVE: To understand the compatibility between the debriding enzymes collagenase and papain, and various wound dressings. DESIGN: The extracts from a silver dressing (Acticoat; Smith & Nephew, St Petersburg, Florida), iodine dressings (Iodoflex and Iodosorb; Smith & Nephew), a pigment-complexed polyvinyl alcohol (PVA) dressing (Hydrofera Blue; Healthpoint, Ltd, Fort Worth, Texas), and collagen dressings (Hydrofera Blue and FibraCol Plus; Systagenix Wound Management, Quincy, Massachusetts) were examined in vitro with collagenase and papain (papain was used in papain-urea debriding agents, no longer available on today's US market). SETTING: All testing was in vitro and performed at Healthpoint, Ltd. PATIENTS: Testing was not performed using human or animal subjects. All in vitro testing was conducted in the lab using artificial wound eschar substrate and other lab equipment. MAIN OUTCOME MEASURES: The main outcome measure was percent collagenase and papain activity lost when combined with each type of dressing tested. MAIN RESULTS: The results demonstrated that the pigment-complexed polyvinyl alcohol dressing and the collagen dressing were compatible with collagenase, whereas the iodine dressings inhibit the activity of collagenase. The nanocrystal silver dressing (Acticoat) caused more than a 50% loss in activity when combined with collagenase. Papain displayed varying levels of inhibition with all dressings tested with the enzyme. The iodine dressings significantly inhibit papain activity, whereas the other dressings exhibited inhibitory activity ranging from 10% to 30%. CONCLUSION: Antimicrobial dressings are widely used for management of wound bioburden. Frequently, they are used in combination with other topical therapeutic drugs, such as enzymatic debriding agents for the removal of wound necrotic tissues. Such combined applications may have greater potential to achieve multiple healing activities simultaneously, including exudate and bioburden management, debridement, and tissue regeneration. Overall, the authors' testing found that collagenase was observed to be more tolerant when used with the dressings tested than papain. These findings merit further exploration in clinical wounds to confirm clinical validity.

A randomized-controlled trial comparing cadexomer iodine and nanocrystalline silver on the healing of leg ulcers.

Chronic leg ulcers are a debilitating, often painful, and costly condition. Leg ulcer healing may be impaired by bacterial colonization, which, unless effective intervention is instigated, can lead to infection. Although it is generally agreed that an antimicrobial dressing is clinically indicated when a wound becomes critically colonized, there is currently no agreement on what constitutes the best practice in the use of antimicrobials. This research compared the effectiveness of two commonly used antimicrobials: nanocrystalline silver and cadexomer iodine. A randomized-controlled trial was conducted in which 281 community nursing clients with leg ulcers compromised by bacterial burden were randomly assigned to have their wounds treated with either silver or iodine dressings. Sixty-four percent of ulcers healed within 12 weeks. The performance of each of the two antimicrobials was comparable in terms of overall healing rate and the number of wounds healed. However, use of silver compounds was associated with a quicker healing rate during the first 2 weeks of treatment and in wounds that were larger, older, and had more exudate. This trial provides some insights as to circumstances in which one product may be preferred over the other.

Chemical surface disinfection of eggs of Baltic cod, Gadus morhua L.

The effect of two disinfectants on eggs and larvae of Baltic cod, Gadus morhua, was investigated. The eggs were disinfected for 10 min using various concentrations of either glutaraldehyde (100, 200, 400, 600 and 800 mg L(-1)) or iodophor (10, 50, 100 and 150 mg L(-1)), 1-4-days post-fertilization. Bactericidal effect of disinfection, survival to hatching, hatching success and larval abnormalities were assessed. Larval survival was recorded at 5-, 10- and 15-days post-hatch (dph). Although Baltic cod eggs have an unusually thin chorion, they could tolerate surface disinfection. A reduction in bacterial growth was observed with increased concentrations of disinfectant (3.0 x 10(7)-1.6 x 10(1) CFU mL(-1)). Abnormalities in newly hatched larvae were not related to disinfection. Survival of the yolk sac larvae was significantly better for eggs treated with 400 mg L(-1) glutaraldehyde for 10 min at 10 and 15 dph. Effective disinfection was also recorded using 100 mg L(-1) Actomar K30. Egg batch effect rather than initial bacterial concentration, disinfectant type or incubation method determined the survival of the eggs to hatching and survival of larvae. Because of the carcinogenic effect of glutaraldehyde, iodophor is recommended for routine disinfection of cod eggs.

Clinico-pathomorphological, serum biochemical and histological studies in broilers fed ochratoxin A and a toxin deactivator (Mycofix Plus).

1. Toxic effects of two concentrations (0.5 and 1 mg/kg) of ochratoxin A (OTA) and attenuating effects of a toxin deactivator (Mycofix Plus(MTV INSIDE)) containing the yeast Trichosporon mycotoxinivorans on the performance (feed conversion ratio; body weight gain), serum enzymes (lactate dehydrogenase, gamma-glutamyltranspeptidase and aspartate aminotransferase) and clinico-pathomorphology of internal organs were studied in 270 one-day-old broiler chicks divided into 9 groups over a 42-d period. 2. Feed conversion ratios (FCR) in groups fed toxin deactivator were improved compared with groups receiving OTA only. An increase in the relative weight of kidney and liver was observed in groups fed 0.5 and 1 mg/kg OTA on day 42 of the experiment as compared with the control group. In contrast, relative weights of bursa of Fabricius and spleen were not significantly affected in experimental groups exposed to OTA as compared to control groups determined on days 28 and 42 of age. 3. Serum enzymes (LDH, GGT and AST) values in OTA treated groups determined on days 28 and 42 were higher than those of the control group. 4. Histopathological examination of kidney on day 42 revealed degenerative changes in the epithelial cells of the proximal convoluted tubules and massive necrosis of the proximal tubular epithelial cells. These changes were less marked in birds receiving 0.5 mg/kg OTA than in those receiving 1 mg/kg. In general, histological changes in kidneys, liver, bursa and spleen were less pronounced in birds receiving OTA and toxin deactivator concomitantly. 5. Dietary OTA at 0.5 and 1 mg/kg adversely affects FCR, increases the serum liver enzymes and induces pronounced pathomorphological and histological changes in internal organs of broiler chicks. Co-administration of OTA with deactivator attenuated the harmful effects.

Electrolyzed oxidizing anode water as a sanitizer for use in abattoirs.

The effectiveness of electrolyzed oxidizing anode (EOA) water (oxidation-reduction potential, 1,120 mV; pH 2.0) as a sanitizer for use in abattoirs was compared with the iodophor (IOD) Mikroklene (25 ppm), a sanitizer approved for use by regulatory authorities in Canada and the United States. A total of 240 swab (100 cm2) samples were obtained from 4 sites on the kill floor and 16 sites in the secondary processing areas, during two visits within a 4-week period to each of three meat packing plants, processing < or =50 animals per week. Swabs were obtained 12 h after the application of IOD and EOA and were analyzed for the presence of total aerobic bacteria, total coliforms, and total Escherichia coli. Total aerobic bacteria (log CFU/ 100 cm2) recovered from the 20 sample sites were lower (P < 0.0001) in EOA as compared with IOD (2.94 +/- 0.12 versus 3.75 +/- 0.12, respectively). Plant A was 1.5 times more likely (P < 0.0001) to have a sampling site positive for the presence of coliforms and E. coli than plants B and C. There was no difference (P > 0.05) between treatment IOD or EOA in the likelihood of obtaining a positive sample for the presence of total coliforms or E. coli among the three plants. When the kill floor and secondary processing areas are compared, the likelihood of obtaining a sample positive for coliforms or E. coli was similar (P > or = 0.05). Results indicate that EOA was more effective than IOD in reducing populations of total aerobic bacteria on equipment surfaces in the three meat packing plants studied. Because the likelihood of obtaining a positive sample for coliforms or E. coli in EOA as compared with IOD was similar, EOA may be a suitable alternative or complement to IOD as a sanitizer in small- to medium-sized abattoirs. Additional research is required to further evaluate the effectiveness of EOA to sanitize processing equipment on the basis of subsequent isolation of aerobes, coliforms, and E. coli from meat products.

[Comparative study on the resistance of Bacteriophage phi chi 174D, T4 and f2 to an iodophor in laboratory].

BACKGROUND: To screen for the most resistant bacteriophage as indicator in disinfection tests, the resistance of bacteriophage phi chi 174D, T4 and f2 to iodophor were observed in laboratory. METHODS: The virucidal activity of iodophor against bacteriophage phi chi 174D, T4, and f2 were assessed by suspension test. The neutralizer is selected and appraised by testing with neutralizer. Bacteriophage phi chi 174D, T4, and f2 were detected and enumerated by the double-agar-layer plaque technique. RESULTS: (1) With 500 mg/L of available iodine of iodophor solution, within a contact time of 40 min, or 750 mg/L, 10 min, or 1000 mg/L, 5 min, the reduction of bacteriophage phi chi 174D could achieve the "disinfection" level [log10 inactivation value (LIV) or log10 reduction value (LRV) of bacteriophage phi chi 174D (log10 No-log10 Nt) was > or = 4.00 log10]. (2) With 600 mg/L of available iodine of iodophor solution, within a contact time of 40 min, or 700 mg/L, 5 min, the reductions of bacteriophage T4 could achieve the "disinfection" level. (3) With 50 mg/L of available iodine of iodophor solution, within a contact time of 10 min, or 75 mg/L, 10 min, the reductions of bacteriophage f2 could achieve the "disinfection" level. CONCLUSION: The order of resistance of the above three bacteriophages to iodophor from greatest to smallest is as follows: bacteriophage phi chi 174D greater than bacteriophage T4 > bacteriophage f2.

[Study on the resistance of Escherichia coli O157:H7 to disinfectants in relationship with its plasmid pO157 and chromosome DNA].

OBJECTIVE: To study the change of Escherichia coli O157:H7 resistance to disinfectants in continuous disinfection and the relationship between the resistance and pO157, chromosome DNA. METHODS: Using 4 disinfectants in a separate manner to disinfect 5 Escherichia coli O157:H7 50 generations continuously, we made a before-after comparison of their resistibility and analyzed the change of the structure of pO157 and chromosome DNA. RESULTS: After the 50-generation-continuous disinfection, the bacteria resistance to sodium dichloroisocyanurate, iodophor and quaternary ammonium increased, but the resistance to chlorhexidiniacetas did not any change; the maps Cal I and Rsr II cutting pO157 revealed some changed after disinfection by sodium dichloroisocyanurate and quaternary ammonium, but the maps showed no change after disinfection by iodophor and chlorhexidiniacetas; the chromosome DNA PFGE maps change considerably after 50 generations of disinfection by sodium dichloroisocyanurate, iodophor and quaternary ammonium, but the chromosome DNA PFGE maps were similar after 50 generation of disinfection by chlorhexidiniacetas. CONCLUSION: The Escherichia coli O157:H7 resistance to disinfectants will increase after the 50-generation-continuous disinfection by sodium dichloroisocyanurate, iodophor and quaternary ammonium. There may be genes both in chromosome DNA and in pO157 which resist sodium dichloroisocyanurate and quaternary ammonium, the reason for increase of resistance may be related with the change of chromosome DNA and pO157. There may be genes in chromosome DNA which resist iodophor, the reason for increase of resistance to iodophor may be related with the change of chromosome DNA, but not related with pO157.

Comparison of susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp. abscessus to disinfectants.

OBJECTIVE: To determine the susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp. absecessus to several frequently-used disinfectants and to evaluate the practicability of surrogating M. tuberculosis by the latter. METHODS: A suspension quantitative bactericidal test was set up in accordance with Chinese Technique Standard for Disinfection to evaluate the susceptibility of each mycobacteria strain to each selected disinfectant. Killing log value was used as criterion in comparing the susceptibility to disinfectants between the two strains. RESULTS: M. chelonei subsp. abscessus was more resistant to chlorine disinfectant than M. tuberculosis while the two strains were similarly resistant to iodophor disinfectant, peracetic acid, alcohol and glutaraldehyde disinfectant. CONCLUSION: M. chelonei subsp. abscessus has the potential to surrogate M. tuberculosis in evaluating mycobactericidal efficacies of disinfectants.

[Study on the resistance of methicillin-resistant staphylococcus aureus to iodophor and chlorhexidine].

OBJECTIVE: To study the resistance of methicillin-resistant staphylococcus aureus (MRSA), an indicator used in hospitals. METHODS: We used minimal inhibitory concentrations (MIC) of iodoph and chlorhexidine to MRSA, methicillin-sensitive staphylococcus aureus (MSSA) and staphylococcus aureus ATCC6538. RESULTS: Obvious difference between MRSA and MSSA the MIC of Iodophor was noticed. Among MICs, 5.3% MRSA strains were 2-folds and 28.9% MRSA strains were 1.5 fold more than staph. aureus ATCC6538, while the MIC of 11.1% MSSA strains raised 1.5 fold than ATCC6538. The MIC of 83.3% MSSA strains were the same to staph. aureus ATCC6538. The MIC of chlorhexidine to MRSA, MSSA and staphylococcus aureus ATTC6538 were similar to each other. CONCLUSION: Results showed that some MRSA were more resistant to Iodophor than staph. aureus ATCC6538, but remained the same resistance to Chlorhexidine. Thus the concentration of Iodophor should be raised when the resistant strains were isolated.