The Antibacterial Efficacy of High-Fluence PACK Cross-Linking Can Be Accelerated.

Purpose: To determine whether high-fluence photoactivated chromophore for keratitis cross-linking (PACK-CXL) can be accelerated. Methods: Solutions of Staphylococcus aureus and Pseudomonas aeruginosa with 0.1% riboflavin were prepared and exposed to 365 nm ultraviolet (UV)-A irradiation of intensities and fluences from 9 to 30 mW/cm2 and from 5.4 to 15.0 J/cm2, respectively, representing nine different accelerated PACK-CXL protocols. Irradiated solutions and unirradiated controls were diluted, plated, and inoculated on agar plates so that the bacterial killing ratios (BKR) could be calculated. Additionally, strains of Achromobacter xylosoxidans, Staphylococcus epidermidis, and Stenotrophomonas maltophilia were exposed to a single accelerated PACK-CXL protocol (intensity: 30 mW/cm2, total fluence: 15.0 J/cm2). Results: With total fluences of 5.4, 10.0, and 15.0 J/cm2, the range of mean BKR for S. aureus was 45.78% to 50.91%, 84.13% to 88.16%, and 97.50% to 99.90%, respectively; the mean BKR for P. aeruginosa was 69.09% to 70.86%, 75.37% to 77.93%, and 82.27% to 91.44%, respectively. The mean BKR was 41.97% for A. xylosoxidans, 65.38% for S. epidermidis, and 78.04% for S. maltophilia for the accelerated PACK-CXL protocol (30 mW/cm2, 15 J/cm2). Conclusions: The BKR of high-fluence PACK-CXL protocols can be accelerated while maintaining a high, but species-dependent, BKR. The Bunsen to Roscoe law is respected in fluences up to 10 J/cm2 in S. aureus and P. aeruginosa, whereas fluences above 10 J/cm2 show strain dependence. Translational Relevance: The high-fluence PACK-CXL protocols can be accelerated in clinical practice while maintaining high levels of BKR.

Case series of Bifidobacterium longum bacteremia in three preterm infants on probiotic therapy.

BACKGROUND: The use of probiotics as prophylaxis for necrotizing enterocolitis (NEC) in preterm infants is being increasingly practised. OBJECTIVE: We report, for the first time, a case series of 3 preterm, very-low-birth-weight (VLBW) infants who developed bacteremia with Bifidobacterium longum on probiotic therapy with Infloran® containing viable B. longum. METHODS: We retrospectively reviewed data of 3 infants (of gestational age <30 weeks and birth weight <1,230 g). They were admitted to the neonatal intensive care unit. Clinical data were retrieved from their medical records. RESULTS: In infants 1 and 2, B. longum was isolated from the blood cultures when they were on probiotic therapy with Infloran or shortly after, respectively, and was interpreted as transient bacteremia. The clinical presentation of these infants did not require antibiotic treatment after the isolation of B. longum. Infant 3 developed an NEC despite probiotic therapy with Infloran and the blood cultures showed B. longum growth. This infant required explorative laparotomy and antibiotic treatment. The clinical isolates of B. longum and the strain of the Infloran capsule showed an identical profile on biochemical, mass-spectrometric and molecular analyses, suggesting a direct correlation between the administration of probiotics and bacteremia with B. longum in all 3 infants. CONCLUSIONS: The occurrence of bacteremia with bifidobacteria after its prophylactic administration in VLBW infants and its possible clinical consequences are a matter of concern. In the interests of safety, the use of probiotics in such a population should be indicated with caution and requires further investigation.

Risk factors for urinary tract infections due to ciprofloxacin-resistant Escherichia coli in a tertiary care urology department in Switzerland.

QUESTIONS UNDER STUDY: Monitoring of antimicrobial resistance is a key component of antibiotic stewardship programs. In 2007, a significantly higher resistance rate of Escherichia coli to ciprofloxacin was found at the Department of Urology, University Hospital Zurich, Switzerland, when compared to other hospital units. Thus, we aimed to determine the risk factors for this increased fluoroquinolone resistance in outpatients and inpatients with urinary tract infection (UTI) or colonisation with E. coli. METHODS: We performed a cross sectional study including 275 patients of the Department of Urology in whom E. coli was isolated from urine or blood cultures between 01.01.2006 and 31.08.2007. Clinical data were collected from patients' records using a structured questionnaire. Multivariable analysis was performed for the detection of risk factors. RESULTS: Ciprofloxacin-resistant E. coli was detected in 22% of patients. Risk factors for ciprofloxacin-resistant E. coli included prior use of fluoroquinolones (odds ratio [OR] (95% confidence intervals): 2.24 (1.08-4.62), p = 0.030), prior urinary tract catheterisation (OR: 2.41 (1.02-5.67), p = 0.044) and recurrent UTIs (OR: 2.26 (1.07-4.78), p = 0.032). 60.8% of all prescriptions in urinary tract infections were for fluoroquinolones, and this antibiotic class was the empiric antibiotic regimen of choice in 72.5% of all acute, uncomplicated, urinary tract infections. CONCLUSIONS: The increasing prevalence of ciprofloxacin-resistant E. coli makes empiric therapy in UTIs with this agent questionable, especially in patients with one or several of the above mentioned risk factors. Due to the increasing resistance rate, continuous surveillance and susceptibility testing in individual patients, particularly with complicated UTIs, is indispensable for adequate therapy.

Actinomyces in chronic granulomatous disease: an emerging and unanticipated pathogen.

BACKGROUND: Chronic granulomatous disease (CGD) is a rare inherited disease of the phagocyte NADPH oxidase system that causes defective production of toxic oxygen metabolites, impaired bacterial and fungal killing, and recurrent life-threatening infections, mostly by catalase-producing organisms. We report for the first time, to our knowledge, chronic infections with Actinomyces species in 10 patients with CGD. Actinomycosis is a chronic granulomatous condition that commonly manifests as cervicofacial, pulmonary, or abdominal disease, caused by slowly progressive infection with oral and gastrointestinal commensal Actinomyces species. Treatment of actinomycosis is usually simple in immunocompetent individuals, requiring long-term, high-dose intravenous penicillin, but is more complicated in those with CGD because of delayed diagnosis and an increased risk of chronic invasive or debilitating disease. METHODS: Actinomyces was identified by culture, staining, 16S ribosomal DNA polymerase chain reaction, and/or a complement fixation test in 10 patients with CGD. RESULTS: All 10 patients presented with a history of fever and elevated inflammatory signs without evident focus. Diagnosis was delayed and clinical course severe and protracted despite high-dose intravenous antibiotic therapy and/or surgery. These results suggest an unrecognized and unanticipated susceptibility to weakly pathogenic Actinomyces species in patients with CGD because these are catalase-negative organisms previously thought to be nonpathogenic in CGD. CONCLUSIONS: Actinomycosis should be vigorously sought and promptly treated in patients with CGD presenting with uncommon and prolonged clinical signs of infection. Actinomycosis is a catalase-negative infection important to consider in CGD.