Catheter lubrication and fixation: interventions

This article looks at the indications for catheterisation, the anatomy of the urethra, the importance of asepsis and the rationale for the use of urethral lubrication for catheter insertion. The variations of lubrication available are discussed, including the use of products containing lidocaine and chlorhexidine. It then considers the problems caused by traction to the catheter and discusses the securement devices available for preventing tissue damage at the bladder neck, within the urethra and also at the meatus. The variation of devices is examined along with the potential problems associated with their use. Finally, it discusses the importance of clinicians being knowledgeable about the problems looked at and how to resolve them.

Predictors of quantitative microbiological analysis of spatter and aerosolization during scaling

The aim of this study is to analyze the infection risk through spatter and aerosolization during scaling and to create a prediction model of the total number of hemolytic bacteria.

MATERIAL AND METHODS

Air samples were collected prior to patient's arrival and spatter and aerosol samples were collected during scaling procedure in 80 patients of 4 different dental clinics. The dentists calculated DI, CI, DMFT. Only patients with CI > = 1 were included. The bacteriological results (CFU/m3) were correlated with clinical indicators. Patients were divided into 2 groups: one that rinse with sterile water and the other with chlohexidine mouth rinse 0.1%.

RESULTS AND CONCLUSIONS

Medium size effect positive correlations were found between the number of decayed teeth and the total number of bacteria and the total number of hemolytic bacteria that grew on plate attached to the dentist's mask. The mean number of bacteria and the mean number of hemolytic bacteria that grew on plate attached to the dentist's mask were significantly lower in the group that rinse with chlorhexidine 0.1%, when compared to the group that rinsed with sterile water. When controlling for the total number of bacteria and the total number of hemolytic bacteria from air sampling, the total number of hemolytic bacteria that grew on the plate attached to the dentist's mask can be predicted by CI, group membership and DMFT score.

Daily chlorhexidine bathing to reduce bacteraemia in critically ill children: a multicentre, cluster-randomised, crossover trial

BACKGROUND

Bacteraemia is an important cause of morbidity and mortality in critically ill children. Our objective was to assess whether daily bathing in chlorhexidine gluconate (CHG) compared with standard bathing practices would reduce bacteraemia in critically ill children.

METHODS

In an unmasked, cluster-randomised, two-period crossover trial, ten paediatric intensive-care units at five hospitals in the USA were randomly assigned a daily bathing routine for admitted patients older than 2 months, either standard bathing practices or using a cloth impregnated with 2% CHG, for a 6-month period. Units switched to the alternative bathing method for a second 6-month period. 6482 admissions were screened for eligibility. The primary outcome was an episode of bacteraemia. We did intention-to-treat (ITT) and per-protocol (PP) analyses. This study is registered with ClinicalTrials.gov (identifier NCT00549393).

FINDINGS

1521 admitted patients were excluded because their length of stay was less than 2 days, and 14 refused to participate. 4947 admissions were eligible for analysis. In the ITT population, a non-significant reduction in incidence of bacteraemia was noted with CHG bathing (3·52 per 1000 days, 95% CI 2·64-4·61) compared with standard practices (4·93 per 1000 days, 3·91-6·15; adjusted incidence rate ratio [aIRR] 0·71, 95% CI 0·42-1·20). In the PP population, incidence of bacteraemia was lower in patients receiving CHG bathing (3·28 per 1000 days, 2·27-4·58) compared with standard practices (4·93 per 1000 days, 3·91-6·15; aIRR 0·64, 0·42-0·98). No serious study-related adverse events were recorded, and the incidence of CHG-associated skin reactions was 1·2 per 1000 days (95% CI 0·60-2·02).

INTERPRETATION

Critically ill children receiving daily CHG bathing had a lower incidence of bacteraemia compared with those receiving a standard bathing routine. Furthermore, the treatment was well tolerated.

FUNDING

Sage Products, US National Institutes of Health.

[Influence of a new biocidal product on the prevalence of digital dermatitis in dairy cows]

OBJECTIVE

It was investigated whether usage of the biocidal product T-Hexx Dragonhyde (Hydromer, Branchburg, NJ, USA) could influence the prevalence of digital dermatitis (DD).

MATERIAL AND METHODS

On a dairy farm (110 milking cows) 48 dairy cows without lameness were selected randomly for a test group or a control (negative) group, respectively. A high prevalence of DD (70-80%) was documented over a period of 2 months, during which four examinations were made, with an interval of 16-21 days between each examination. The respective grade of the DD-lesion on the hind hoofs was documented according to a scoring scheme. After precleaning the claws with water, the test group passed through a hoof bath containing T-Hexx Dragonhyde on 2 days per week at two milking times on each day, whereas the claws of control animals were cleaned using only a water bath. Splashes contaminating the animals and the environment were documented photographically and evaluated. Bacteriological examinations of the water bath and the T-Hexx-bath were performed after increasing numbers of animals had passed through the baths.

RESULTS

Between and within groups no statistically significant differences in the prevalence of DD were found. DD-lesion scoring did not show any difference between the groups. With increasing numbers of animals having passed through the water bath, there was a significant increase in colony-forming units per millilitre and of enterobacteriaceae. In the T-Hexx Dragonhyde footbath, bacterial contamination remained below the detection limit at all times. The coloured splashes of the footbath were visible up to the level of the udder and teats.

CONCLUSION AND CLINICAL RELEVANCE

The prevalence of DD was not influenced by the 2% or 4% concentration of the biocidal product in the footbath. Thus the microbiocidal effect of the solution did not lead to an efficient reduction in bacteria on the hoof. To demonstrate a potential preventive effect on DD, future studies would require herds with lower prevalence and a higher sample size. However, when applying footbaths there is the general risk of milk contamination or causing mastitis.

[Cleanliness of the walls of root canals in teeth with incomplete development of root, rinsed with 2% chlorexidine. A SEM study]

INTRODUCTION

The aim of the study was to evaluate the cleanliness of the walls of root canals with incomplete development of root, whose lumen was rinsed with 2% chlorhexidine solution during mechanical preparation.

MATERIAL AND METHODS

Use was made of 8 maxillary premolar teeth with a single root canal and with incomplete development of the root apex (the teeth were removed during the growing stage for orthodontic reasons). The coronal and middle parts of the canals were instrumented using Gates-Glidden no. 3 and 4 drills, and the apical section with the help of Hedstroem size 50-80 files. During instrumentation of the canals irrigation was carried out using 2% chlorhexidine solution. Irrigating solution, volume 2 mL, was introduced into the canal with the use of a syringe and an endodontic needle after using each instrument, and 5 mL volume after complete instrumentation of the canal.

RESULTS

Observations using a scanning electron microscope with x200 and x1000 magnification showed relatively effective removal of pulp remains and dentine chips, and the presence of a thick smear layer covering the canal walls throughout their length. Statistical analysis did not show significant differences in the degree of cleaning of particular sections of the canals.

CONCLUSION

The presence of the smear layer in canals irrigated with chlorhexidine is evidence that it does not have properties for it to be dissolved, and this dictates the necessity of using chelating agents.

Radiologic evaluation of bone loss at implants with biocide coated titanium abutments: a study in the dog

The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed plaque accumulation, and after 15 weeks the dogs were sacrificed. Radiographs of all implant sites were obtained at the beginning and at the end of the experimentally induced peri-implantitis. The radiographic examination indicated that significant amounts of additional bone loss occurred in implants without biocide coating, considering both absolute and relative values of bone loss. Percentages of additional bone loss observed in implants dressed with a biocide coated abutment were about 3 times lower (p<0.006 distal aspect; and p<0.031 at mesial aspect) than the control ones. Within the limits of the present study it seems promising the use of soda-lime glass/nAg coatings on abutments to prevent peri-implant diseases.

Evaluation with a focus on both the antimicrobial efficacy and cumulative skin irritation potential of chlorhexidine gluconate alcohol-containing preoperative skin preparations

BACKGROUND

Important characteristics for ideal skin preparations include long-lasting antimicrobial efficacy and low potential for skin irritation.

METHODS

A total of 55 healthy adult subjects were enrolled to evaluate the antimicrobial effects of 3 test formulations applied to inguinal, abdominal, and antecubital sites at post-treatment time points of 30 seconds, 72 hours, and 7 days. To investigate skin irritation potential, the 3 formulations were tested in a 21-day repeat-insult patch test conducted on the skin of the backs of 23 healthy subjects.

RESULTS

The mean log(10) reduction (MLR) at 7 days post-treatment produced by a 79% vol/vol ethanol containing 1% wt/vol chlorhexidine gluconate (1% CHG-EtOH) applied to abdominal sites was significantly superior to that produced by a 10% povidone-iodine solution (2.45 MLR vs 0.90 MLR; P < .05). The 1% CHG-EtOH and a 70% vol/vol isopropanol containing 2% wt/vol CHG (2% CHG-IPA) provided statistically equivalent persistence at 72 hours and 7 days post-treatment. The 1% CHG-EtOH had less skin irritation potential than the 2% CHG-IPA and the 10% povidone-iodine solution, although the differences were not statistically significant (P > .05).

CONCLUSION

Considering its persistent effect and low skin irritation potential, the 1% CHG-EtOH preparation is expected to perform well in surgical site preparation to reduce the risk of surgery- and catheter-related bloodstream infection.

Impact of chloramination on the development of laboratory-grown biofilms fed with filter-pretreated groundwater

This study evaluated the continuous impact of monochloramine disinfection on laboratory-grown biofilms through the characterization of biofilm architecture and microbial community structure. Biofilm development and disinfection were achieved using CDC (Centers for Disease Control and Prevention) biofilm reactor systems with polyvinyl chloride (PVC) coupons as the substratum and sand filter-pretreated groundwater as the source of microbial seeding and growth nutrient. After 2 weeks of growth, the biofilms were subjected to chloramination for 8 more weeks at concentrations of 7.5±1.4 to 9.1±0.4 mg Cl2 L(-1). Control reactors received no disinfection during the development of biofilms. Confocal laser scanning microscopy and image analysis indicated that chloramination could lead to 81.4-83.5% and 86.3-95.6% reduction in biofilm biomass and thickness, respectively, but could not eliminate biofilm growth. 16S rRNA gene terminal restriction fragment length polymorphism analysis indicated that microbial community structures between chloraminated and non-chloraminated biofilms exhibited different successional trends. 16S rRNA gene pyrosequencing analysis further revealed that chloramination could select members of Actinobacteria and Acidobacteria as the dominant populations, whereas natural development leads to the selection of members of Nitrospira and Bacteroidetes as dominant biofilm populations. Overall, chloramination treatment could alter the growth of multi-species biofilms on the PVC surface, shape the biofilm architecture, and select a certain microbial community that can survive or proliferate under chloramination.

Effectiveness of hand hygiene and provision of information in preventing influenza cases requiring hospitalization

BACKGROUND

The objective of the study was to investigate the effectiveness of non-pharmacological interventions in preventing cases of influenza requiring hospitalization.

METHODS

We performed a multicenter case-control study in 36 hospitals, in 2010 in Spain. Hospitalized influenza cases confirmed by reverse-transcription polymerase chain reaction and three matched controls (two hospital and one community control) per case were selected. The use of non-pharmacological measures seven days before the onset of symptoms (frequency of hand washing, use of alcohol-based hand sanitizers and handwashing after touching contaminated surfaces) was collected.

RESULTS

We studied 813 cases hospitalized for influenza and 2274 controls. The frequency of hand washing 5-10 times (adjusted odds ratio [aOR]=0.65) and >10 times (aOR=0.59) and handwashing after contact with contaminated surfaces (aOR=0.65) were protective factors and were dose-responsive (p<0.001). Alcohol-based hand sanitizers were associated with marginal benefits (aOR=0.82).

CONCLUSIONS

Frequent handwashing should be recommended to prevent influenza cases requiring hospitalization.

Ozone disinfection of eggs from gilthead seabream Sparus aurata, sea bass Dicentrarchus labrax, red porgy, and common dentex Dentex dentex

The risk of fish pathogen transmission via eggs can be reduced by disinfection in ozonated seawater. The aim of this study was to determine the suitable conditions for ozone disinfection of the eggs of gilthead seabream Sparus aurata, sea bass Dicentrarchus labrax, red porgy Pagrus pagrus, and common dentex Dentex dentex. The eggs were disinfected with a concentration (C) of 0.5 mg of ozone/L of water at four different exposure times (T = 2, 4, 8, and 16 min). The hatching rate was determined in triplicate for each treatment. Bacterial colonies were counted on tryptic soy agar and thiosulfate-citrate-bile salts-sucrose agar. At the end of the experiment, bacterial load and hatching rate were assessed together to determine the optimal ozone treatment values, which were estimated in CT units (i.e., C [= 0.5 mg/L] x T [min]). Optimal values were CT 2-4 (T = 4-8 min; 18 degrees C) for gilthead seabream and red porgy, CT 2 (T = 4 min; 18 degrees C) for common dentex, and CT 4 (T = 8 min; 15 degrees C) for sea bass.

Do hospital visitors wash their hands? Assessing the use of alcohol-based hand sanitizer in a hospital lobby

BACKGROUND

Reports regarding hand hygiene compliance (HHC) among hospital visitors are limited. Although there is an implicit assumption that the availability of alcohol-based hand sanitizer (AHS) promotes visitor HHC, the degree of AHS use by visitors remains unclear. To assess AHS use, we observed visitor HHC and how it is affected by visual cues in a private university hospital.

METHODS

Using an observational controlled study, we tested 3 interventions: a desk sign mandating all visitors to use AHS, a free-standing AHS dispenser directly in front of a security desk, and a combination of a freestanding AHS dispenser and a sign.

RESULTS

HHC was 0.52% at baseline and did not improve significantly when the desk sign was provided as a cue 0.67% (P = .753). However, HHC did improve significantly with use of the freestanding AHS dispenser (9.33%) and the sign and dispenser combination (11.67%) (P < .001 for all comparisons of dispenser alone and sign and dispenser with baseline and sign alone). The degree of improvement with the sign and dispenser combination over the dispenser was not statistically significant.

CONCLUSIONS

Hospital visitors represent an important factor in infection prevention. A coordinated effort is needed to increase visitor HHC, including an evaluation of the AHS placement, education of visitors on the importance of HHC, and evaluation of corresponding changes in hand hygiene behavior.

Effect of surgical site infections with waterless and traditional hand scrubbing protocols on bacterial growth

BACKGROUND

Alcohol-based antiseptic scrub formulation has long been used for hand cleansing in the operating room. Recently, a waterless surgical scrub formulation containing 1% chlorhexidine gluconate was developed to provide a comparable antiseptic effect. The present study explored the scrub time required when using waterless hand scrub and traditional hand scrub formulations for operating room staff and compared bacterial growth on the hands after surgical hand scrubbing in the 2 groups.

METHODS

Operating room staff members (n = 100) were recruited randomly from medical centers in Taiwan. Two days in July 2010 were chosen for testing in advance, and the participants were assigned equally to use either a waterless scrub or traditional scrub formulation on 2 separate days. Scrub times were recorded and microorganisms on hands after scrubbing were sampled on 2 separate days. Two days after sampling, the colonies grown on bacterial culture plates were counted and expressed as colony-forming units (CFU) per plate.

RESULTS

At 48 hours after sampling, microorganisms were found on 7 of the 50 plates in the waterless scrub group (1-9 CFU) and on 7 of the 50 plates in the traditional scrub group (1-5 CFU). The difference between the groups was no statistically significant (95% CI, 0.85-1.71). Nine surgical patients were found to have contact with the 14 participants with microorganisms found after scrubbing in the operating room. Among these 9 patients, 1 patient with diabetes who underwent amputation developed local reddish swelling suggestive of surgical site infection necessitating a 7-day course of cefalexin. The incidence of surgical site infection was not signifcantly different in the 2 groups.

CONCLUSIONS

Our findings suggest that waterless hand scrub is as effective as traditional hand scrub in cleansing the hands of microorganisms and more efficient in terms of scrub time.

[Legal aspects of the use of footbaths for cattle and sheep]

Claw diseases pose a major problem for dairy and sheep farms. As well as systemic treatments of these illnesses by means of drug injection, veterinarians discuss the application of footbaths for the local treatment of dermatitis digitalis or foot rot. On farms footbaths are used with different substances and for various purposes. The author presents the requirements for veterinary medicinal products (marketing authorization and manufacturing authorization) and demonstrates the operation of the "cascade in case of a treatment crisis". In addition, the distinction between veterinary hygiene biocidal products and veterinary medicinal products and substances to care for claws is explained.

[The effectiveness of hand hygiene products on MRSA colonization of health care workers by using CHROMagar MRSA]

The aims of this study were; to investigate the hand hygiene compliance of the health care workers (HCWs) during their routine patient care, to determine the methicillin-resistant Staphylococcus aureus (MRSA) hand colonization of the HCWs, to investigate the effect of different hand hygiene products on MRSA colonization and to evaluate the effectiveness of chromogenic agar for detecting MRSA. HCWs were investigated during their routine patient care and hand cultures were taken before and after hand wash/hygiene. Two different techniques were used to obtain the hand cultures: fingertip method (CHROMagar MRSA containing HygiSlide); and direct swab method and then inoculation to CHROMagar MRSA media. MRSA strains grown on those cultures were confirmed with conventional methods. A total of 100 HCWs (of them 61 were female; mean age: 32.7 ± 5.2 years; age range: 25-51 years) involving physicians (n= 33), nurses (n= 38) and health care assistants (n= 29), were included in the study. MRSA was detected in 39% and 11% before hand hygiene and in 13% and 6% after hand hygiene, with HygiSlide CHROMagar media and with CHROMagar in plate media, respectively. No difference were found regarding clinics, occupations, or the type of patient handling in those HCWs who were positive (n= 13) for MRSA colonization following hand hygiene, and those who were negative (n= 26). However, the type of the hand hygiene product used exhibited a statistical difference. None of the seven HCWs who used alcohol based hand rub revealed growth in the second culture while 10 of 19 (53%) HCWs who used soap and three of 13 (23%) HCWs who used chlorhexidine were still colonized with MRSA. In terms of reduction in the MRSA counts, the most effective one was the alcohol based hand rub while the soap was the least, since seven of 19 (37%) HCWs who used soap showed no reduction at all in the MRSA counts. A high ratio of hand colonization with MRSA was detected in our hospital staff (39%). It was shown that the colonization could be reduced significantly (with a rate of 66%) with hand hygiene. Alcohol based hand rub was found to be the most effective method in hand hygiene. The fingertip technique was found to be superior to inoculation to plate media for obtaining hand cultures and CHROMagar MRSA media was found to be rapid, effective and practical for detecting the MRSA hand colonization.

Analysis of exit site care on IV antibiotic use in facilities using electrolytically produced sodium hypochlorite: a pilot retrospective study

In a retrospective survey of 226 dialysis facilities, the present study compared the effectiveness of topical disinfection with electrolytically produced sodium hypochlorite (ESH) and povidone iodine in preventing central venous catheter-related infections by tracking intravenous (IV) antibiotic administration. In patients undergoing hemodialysis, 18.1% of patients in ESH facilities and 19.2% of patients in povidone iodine facilities were administered IV antibiotics one or more times during the six-month study (p = 0.09). These findings suggest that ESH and povidone iodine are comparable in effectiveness for exit site care in patients dialyzing with central venous catheters.

Adsorption and release of biocides with mesoporous silica nanoparticles

In this proof-of-concept study, an agricultural biocide (imidacloprid) was effectively loaded into the mesoporous silica nanoparticles (MSNs) with different pore sizes, morphologies and mesoporous structures for termite control. This resulted in nanoparticles with a large surface area, tunable pore diameter and small particle size, which are ideal carriers for adsorption and controlled release of imidacloprid. The effect of pore size, surface area and mesoporous structure on uptake and release of imidacloprid was systematically studied. It was found that the adsorption amount and release profile of imidacloprid were dependent on the type of mesoporous structure and surface area of particles. Specifically, MCM-48 type mesoporous silica nanoparticles with a three dimensional (3D) open network structure and high surface area displayed the highest adsorption capacity compared to other types of silica nanoparticles. Release of imidacloprid from these nanoparticles was found to be controlled over 48 hours. Finally, in vivo laboratory testing on termite control proved the efficacy of these nanoparticles as delivery carriers for biopesticides. We believe that the present study will contribute to the design of more effective controlled and targeted delivery for other biomolecules.

Strategies for prevention of ventilator-associated pneumonia: bundles, devices, and medications for improved patient outcomes

Ventilator-associated pneumonia is associated with significant patient morbidity, mortality, and increased health care costs. In the current economic climate, it is crucial to implement cost-effective prevention strategies that have proven efficacy. Multiple prevention measures have been proposed by various expert panels. Global strategies have focused on infection control, and reduction of lower airway colonization with bacterial pathogens, intubation, duration of mechanical ventilation, and length of stay in the intensive care unit. Routine use of the Institute for Healthcare Improvement ventilator care bundle is widespread, and has been clearly demonstrated to be an effective method for reducing the incidence of ventilator-associated pneumonia. In this article, we examine specific aspects of the Institute for Healthcare Improvement bundle, better-designed endotracheal tubes, use of antibiotics and probiotics, and treatment of ventilator-associated tracheobronchitis to prevent ventilator-associated pneumonia.

Antimicrobial gauze as a dressing reduces pin site infection: a randomized controlled trial

BACKGROUND

Pin site infection is a common problem in external fixation. Plain gauze wetted with normal saline is commonly used for a pin site dressing owing to the simplicity and low cost. Evidence to support adding an antimicrobial agent in the dressing material is lacking.

QUESTIONS/PURPOSES

We compared the rate of pin tract infection using plain gauze and gauze impregnated with polyhexamethylene biguanide in patients undergoing limb lengthening procedures.

PATIENTS AND METHODS

We included 38 patients (40 limbs) undergoing limb lengthening or deformity correction using an external fixator between July 2009 and June 2010. There were 23 male patients and 15 female patients, with a mean age of 26.3 years (range, 5-68 years). The patients were randomized into two groups: a polyhexamethylene biguanide group (22 limbs) and a control group (18 limbs). The metal-skin interfaces were assessed by a researcher blinded to the type of gauze at 2, 4, 8, and 12 weeks after surgery for the pin site infection based on a predetermined grading system. There were a total of 483 metal-skin interfaces, with 1932 total observations. Infection rates were compared using the chi square test and relative risk with 95% confidence interval.

RESULTS

The infection rate was lower (χ(2) [1, n = 1932] = 23.00) and the risk for infection was lower (relative risk, 0.228; 95% confidence interval, 0.118, 0.443) for the polyhexamethylene biguanide group (n = 1068; 1.0%) than for the control group (n = 864; 4.5%).

CONCLUSIONS

Use of polyhexamethylene biguanide-impregnated gauze can reduce the risk of pin tract infection in external fixation.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

[Significance of the efflux phenomenon as a mechanism of bacterial resistance on active substances of biocide]

Efflux phenomenon induced by the presence of efflux pumps is one of the bacterial resistance mechanisms against active substances ofbiocides. Proteins and protein systems create efflux pumps, which are connected with the cell envelope structure ofbacteria. The efflux pump's function is transportation of active substances of disinfectants outside the bacterial cell. The biocides active substances rinsed out of bacterial cell by efflux were described for quaternary ammonium compounds, biguanides, phenols and diamidine. Bacterial resistance induced by efflux was not confirmed in the presence of such active substances like: alcohols, aldehydes, peroxides and chlorine compounds and their derivates. Bacterial resistance to active substance ofbiocides can be caused by two or more resistance mechanisms i.e. efflux mechanisms and reduce diffusion. The cooperation of resistance mechanisms to biocides can result difficulties in pathogenic bacteria eradication. The spread of these bacteria can be an epidemic threat.

Control of biofouling by Cordylophora caspia in freshwater using one-off, pulsed and intermittent dosing of chlorine: laboratory evaluation

Cordylophora caspia is a hydrozoan which causes biofouling in power plants and is an increasing problem in UK drinking water treatment works. Thermal control is not usually feasible without a ready source of hot water so laboratory experiments were conducted to assess whether using pulsed doses of chlorine is an alternative solution. C. caspia polyps disintegrated after a single 20 min dose (the length of one backwash cycle in water treatment work filter beds) of 2.5 ppm chlorine. Without further treatment colonies regenerated within 3 days, but repeated dosing with chlorine for 20 min each day inhibited this regeneration. The resistance of surviving colonies to chlorine increased over time, although colony size and polyp regeneration continued to fall. These results suggest pulsed treatment with chlorinated backwashes at 2 ppm could be used to control C. caspia biofouling in rapid gravity filters and this may have relevance to other settings where thermal control is not feasible.