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ABSTRACT: Bacteria such as staphylococci commonly encountered in orthopaedic infections form biofilms and adhere to bone implants and cements. Various methods to disrupt the biofilm and enhance bacterial detection have been reported. We will describe the effectiveness of vortexing and sonication to improve the detection of biofilm-formative bacteria from polymethylmethacrylate by conventional quantitative bacterial culture and real-time quantitative PCR. We used a single biofilm-formative Staphylococcus aureus strain and 20 polymethylmethacrylate coupons as an in vitro biofilm model; four coupons were used for each of two control groups or three experimental sonication times (1, 5, and 30 minutes). Vortexing the cement without sonication increased the yield of adherent bacteria to a considerable extent. The combination of vortexing and sonication further enhanced the yield regardless of the duration of sonication. Quantitative conventional cultures correlated with quantitative PCR assay. The combination of vortexing and sonication to disrupt the bacterial biofilm followed by quantitative PCR and/or culture seems to be a sensitive method for detecting bacteria adherent to bone cement.
Clinical Orthopaedics and Related Research 12/2008; 467(5):1360-4. · 2.53 Impact Factor
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ABSTRACT: Detailed human studies of the mechanisms and development of shunt infection in real time are not possible, and we have developed a canine hydrocephalus model to overcome this. The intention of this pilot study was to show that the canine hydrocephalus model could be shunted using conventional "human" shunts, and that a shunt infection could be established so that further studies could then be planned.
Hydrocephalus was induced in seven dogs (Canis familiaris) by fourth ventricle obstruction. Four weeks later they were shunted using a Hakim Precision valve. Four of the dogs received shunts whose ventricular catheter had been inoculated with Staphylococcus epidermidis, and three were uninoculated controls. Four weeks after shunting the dogs were sacrificed and necropsy was performed. Removed shunts and tissue samples were examined microbiologically and isolates were subjected to detailed identification and genomic comparison.
All the dogs remained well after shunting. Examination of removed shunt components revealed S. epidermidis in the brain and throughout the shunt system in the four inoculated animals, but in two of these Staphylococcus intermedius was also found. S. intermedius was also isolated from all three "negative" controls. There were slight differences between S. intermedius strains suggesting endogenous infection rather than cross- infection from a point source.
Shunt infection was established in the canine model, and had the experiment been extended beyond four weeks the typical microbiological, pathological and clinical features might have appeared. The occurrence of unplanned shunt infections in control animals due to canine normal skin flora reflects human clinical experience and underlines the usual source of bacteria causing shunt infection.
Cerebrospinal Fluid Research 11/2008; 5:17. · 1.81 Impact Factor
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ABSTRACT: Community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) have recently emerged as a major cause of serious infections among older children and are now being seen in NICU patients. We present the case of a preterm infant with CA-MRSA necrotizing pneumonia and secondary bacteremia.
Pediatric Pulmonology 03/2008; 43(2):203-5. · 2.53 Impact Factor
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ABSTRACT: To describe a new technique, pyrosequencing, which allows for the rapid identification of Mycobacterium and Nocardia species.
Interventional case report.
The medical records of a patient presenting with an infectious keratitis were reviewed.
A case of Nocardia abscessus/arthrititis/asiatica keratitis was diagnosed in a young individual with the aid of pyrosequencing technology. Based on presumed antibiotic sensitivities, therapy with topical trimethoprim-sulfamethoxazole eyedrops was initiated, and the infection was cleared rapidly with minimal residual scarring.
Pyrosequencing may be a useful tool in aiding the rapid diagnosis and treatment of ocular infections caused by slow-growing pathogens.
American Journal of Ophthalmology 02/2007; 143(1):182-3. · 4.22 Impact Factor
