Amoebicidal activity of a preserved contact lens multipurpose disinfecting solution compared to a disinfection/neutralisation peroxide system.

The amoebicidal activity of a contact lens multipurpose disinfecting solution (MPDS) containing polyquaternium-1 and myristamidopropyl dimethylamine was compared to a disinfection/neutralisation peroxide system against Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. A quantitative microtitre method was used to evaluate the solutions. The MPDS showed similar amoebicidal activity to the disinfection/neutralisation peroxide system against the trophozoites of both species and equal or more rapid activity against the cysts of both species.

0.3% ciprofloxacin ophthalmic ointment in the treatment of bacterial keratitis. The Ciprofloxacin Ointment/Bacterial Keratitis Study Group.

OBJECTIVE: To determine the efficacy and safety of topical 0.3% ciprofloxacin hydrochloride ophthalmic ointment in the treatment of bacterial keratitis. DESIGN: Prospective case series with a nonrandomized comparison of culture-positive, evaluable cases (ciprofloxacin ointment group) with culture-positive, concurrent patients (nonenrolled group) treated with conventional therapy. SETTING: Multicenter clinical study. PATIENTS: After informed consent was obtained, 253 eligible patients underwent corneal scrapings and received topical ciprofloxacin ointment; 145 (57%) had positive cultures and completed the follow-up schedule. Forty (70%) of 57 apparently eligible patients had culture-positive bacterial keratitis but were not enrolled in the ciprofloxacin ointment study during the same period. INTERVENTION: Ciprofloxacin ophthalmic ointment instilled every 1 to 2 hours for 2 days, then every 4 hours for 12 days. MAIN OUTCOME MEASURES: Clinical evaluation of signs at 1, 3, 7, and 14 days of treatment and the overall condition classified as clinical success (cured or improved) or failure (unchanged or worse) during and after therapy. RESULTS: Clinical success with the initial treatment occurred in 135 patients (93%) in the ciprofloxacin ointment group and in 28 patients (70%) in the nonenrolled group. Of the 10 ciprofloxacin clinical failures, seven were staphylococcal; two, pneumococcal; and one, polybacterial. The 90% minimum inhibitory concentration of ciprofloxacin was 3 mg/L or less for corneal bacterial isolates. No serious adverse event attributable to ciprofloxacin ointment occurred, although 32 (13%) of 253 patients developed a transient white crystalline corneal precipitate shown with liquid chromatography in two cases to be ciprofloxacin. CONCLUSION: Ciprofloxacin ophthalmic ointment is an effective and safe topical antimicrobial agent for the treatment of bacterial keratitis caused by susceptible microorganisms.

Deposition of ciprofloxacin, prednisolone phosphate, and prednisolone acetate in SeeQuence disposable contact lenses.

We noted opaque deposits in SeeQuence disposable contact lenses in three patients with persistent epithelial defects who were being treated with topical ciprofloxacin and prednisolone acetate. In each patient, the contact lenses with deposits were removed and replaced. High performance liquid chromatography analysis revealed the deposits to be precipitates of ciprofloxacin and prednisolone acetate. We incubated new SeeQuence disposable contact lenses in ciprofloxacin, prednisolone phosphate, and prednisolone acetate alone and in combination. Precipitates did form when ciprofloxacin was combined with either prednisolone acetate or prednisolone phosphate. We recommend removal and replacement of contact lenses should these deposits develop to prevent the possibility of corneal toxicity.

Resistance of selected strains of Pseudomonas aeruginosa to low-intensity ultraviolet radiation.

The resistances of 10 strains of Pseudomonas aeruginosa and other microorganisms to an ultraviolet (UV) intensity of 100 muW/cm2 were determined. Organisms were exposed in 2- or 15-ml saline suspensions contained in uncapped polyethylene bottles for increasing periods of time, and the surviving fractions were enumerated. Decimal reduction times were calculated by regression analysis, using the least-squares method. The 10 strains of P. aeruginosa, compared with Micrococcus radiodurans and Candida albicans, were very susceptible to low-intensity UV radiation. Results from this study showed that a UV intensity of 100 muW/cm2 penetrated saline suspensions up to 40 mm deep sufficiently to kill high levels of microbial cells, especially P. aeruginosa cells. These results allowed us to design a system for determining and monitoring the sterilization capability of low-intensity UV radiation. In our particular case, UV proved to be an efficient mode for sterilizing saline suspensions of P. aeruginosa in polyethylene bottles. The significance and application of these findings with regard to supporting UV as a sterilant are discussed.

Quantitative ocular bacteriology: a method for the enumeration and identification of bacteria from the skin-lash margin and conjunctiva.

Type 1 Calgiswabs were used to collect bacterial specimens from the skin-lash margins and conjunctivae of normal volunteers. The swabs were held in a nonnutritive balanced salt solution during transportation to the laboratory. Alginate swabs were dissolved in a two-step procedure in TC Eagle's medium and 2.5% sodium hexametaphosphate solution. Aliquots of suspended bacteria from the dissolved swab were plated on blood agar. After incubation, bacterial colonies present were enumerated and identified. Cultures from both the skin-lash margin and conjunctiva show significant variation in the number and types of microorganisms isolated. Quantities of bacteria isolated from the lid margin were usually greater than from the conjunctiva. Staphylococcus epidermidis was the most prevalent bacterium isolated. The adsorption of bacteria onto alginate swabs from bacterial suspensions and the recovery of a red pigment-producing organism from the conjunctivae of rabbit eyes previously inoculated show that the method is sensitive and highly reproducible.

Resistance and recovery studies on ultraviolet-irradiated spores of Bacillus pumilus.

A spore suspension model and a procedure for recovering ultraviolet (UV)-irradiated spores of Bacillus pumilus were investigated. A most-probable-number tube dilution method using double-strength Trypticase soy broth was found to be superior to the agar plate method for recovering optimal numbers of spores irradiated with sublethal doses of UV energy. Aqueous suspensions of B. pumilus survived UV doses up to 108,000 ergs/mm2 as determined by a most-probable-number recovery and estimation procedure. Resistance and stability data were consistent and reproducible, indicating the dependability of this method for recovering UV-damaged spores. The procedures used to collect information concerning resistance characteristics for two strains of B. pumilus are discussed.

Serological study of trichloroacetic acid extracts of Bacteroides fragilis.

Immunodiffusion techniques were used on trichloroacetic acid extracts from 10 strains of Bacteroides fragilis in detecting precipitating antibodies against this species in immune rabbit sera. Species and even strain specificities were observed in these precipitin reactions. Multiple antigens were detected in the extracts from some strains, whereas only one precipitin band per extract developed during agar-gel diffusion tests of others. The antigen extracts were found to be both heat stable and resistant to hydrolysis by alpha-chymotrypsin. Four serological patterns were demonstrated in homologous and heterologous reactions with the B. fragilis. antigen-antibody systems used. The results showed that some strains were serologically distinct from others, indicating that the strains tested are of more than one serotype.

Fluorescent-antibody studies on selected strains of Bacteroides fragilis subspecies fragilis.

Antisera against seven strains of Bacteroides fragilis subspecies fragilis were produced from dense suspensions of whole cells. These sera exhibited high agglutination titers with homologous antigens. Reciprocal cross-reactions in agglutination tests with each immunizing strain yielded lower titers. Both the indirect and direct fluorescent-antibody techniques were used to evaluate these reagents in the serological identification of 24 defined strains of B. fragilis subspecies fragilis. Subspecies and even strain specificities were noted with particular antisera. A pooled antiserum and conjugate were prepared and studied. Study results showed that specific and high-titered antisera against strains within this subspecies can be produced by the methods described herein and that possibly more than one serotype exists within the seven strains studied. The development of more antibody pools will be necessary to encompass a wider antigenic coverage before the fluorescent-antibody technique can be relied upon altogether for serologically identifying isolates of B. fragilis subspecies fragilis. Test data showed that the indirect method of fluorescent-antibody staining with whole antiserum is an excellent means of identifying strains of this organism.

Evaluation of a new presumptive medium for group D streptococci.

A new medium designated as D streptococcus-enterococcus broth was formulated and evaluated for the enrichment and isolation of strains of serological group D streptococci. This medium was made by modifying Todd-Hewitt broth. Most-probable-number multiple-tube and membrane filter techniques were employed to estimate the numbers of enterococci in known cultures, wastewater, and other samples. Preliminary most-probable-number counts with this medium were as much as 3 logs higher than those counts obtained from four other media with which it was compared. The methodology for using this medium to estimate the numbers of group D streptococci in water is discussed.

Detection of enteropathogenic Escherichia coli strains in wastewater by fluorescent antibody.

Flourescent antibody (FA) techniques were used to evaluate fluorescein-labeled enteropathogenic Escherichia coli (EEC) OB globulins as a means of presumptively detecting these serogroups in wastewater. Four of the more prevalent and incriminated EEC serogroups were detected by FA and isolated from wastewater. A total of 317 sewage isolates biochemically defined as E. coli were tested by FA and agglutination tests. Only a small number of these isolates (9/317, 2.8%) were serologically groups as being enteropathogenic related strains. The frequency of occurrence of EEC organisms in a wastewater, as determined by FA, is reported. The use of highly specific OB fluorescent antibodies to monitor wastewater for the presence of EEC is discussed.

Evaluation of a most-probable-number technique for the enumeration of Pseudomonas aeruginosa.

A most-probable-number (MPN) technique was evaluated for detecting and enumerating Pseudomonas aeruginosa in water and wastewater. Both the presumptive and confirmatory media, as described in the 13th edition of Standard Methods for the Examination of Water and Wastewater, as well as modifications of these media were included in evaluations. Various samples of water were tested, namely chlorinated tap water, creek water, and influent to a wastewater treatment plant. Modified media repeatedly gave higher estimated MPNs of P. aeruginosa than media listed in Standard Methods. P. aeruginosa was detected and recovered from all creek water and wastewater samples, but not from tap water samples tested. This organism was determined to be present in as large numbers as the fecal coliforms and in even greater quantities than the fecal streptococci in all samples, whenever MPN estimations were determined from those positive tubes containing the modified confirmatory medium.