Patel, Robin

ABSTRACT Small colony variants (SCVs) are naturally occurring subpopulations of bacteria. The clinical characteristics and treatment outcomes of patients with prosthetic joint infection (PJI) caused by staphylococcal SCVs are unknown. This study was a retrospective series of 113 patients with staphylococcal PJI, with prospective testing of archived sonicate fluid samples. SCVs were defined using two-investigator review. Treatment failure was defined as (i) subsequent revision surgery for any reason, (ii) PJI after the index surgery, (iii) prosthesis nonreimplantation due to ongoing infection, or (iv) amputation of the affected limb. There were 38 subjects (34%) with SCVs and 75 (66%) with only normal-phenotype (NP) bacteria. Subjects with SCVs were more likely to have been on chronic antimicrobials prior to surgery ( P = 0.048), have had prior surgery for PJI ( P = 0.03), have had a longer duration of symptoms ( P = 0.0003), and have had a longer time since joint implantation ( P = 0.007), compared to those with only NP bacteria. Over a median follow-up of 30.6 months, 9 subjects (24%) with SCVs and 23 (32%) with only NP bacteria experienced treatment failure ( P = 0.51). Subjects infected with Staphylococcus aureus were more likely to fail than were those infected with Staphylococcus epidermidis (hazard ratio [HR], 4.03; 95% confidence interval [CI], 1.80 to 9.04). While frequently identified in subjects with PJI and associated with several potential predisposing factors, SCVs were not associated with excess treatment failure compared to NP infections in this study, where they were primarily managed with two-stage arthroplasty exchange. IMPORTANCE Bacteria with the small colony variant (SCV) phenotype are described in small case series as causing persistent or relapsing infection, but there are insufficient data to suggest that they should be managed differently than infection with normal-phenotype bacteria. In an effort to investigate the clinical importance of this phenotype, we determined whether SCVs were present in biofilms dislodged from the surfaces of arthroplasties of patients with staphylococcal prosthetic joint infection and assessed the clinical outcomes associated with detection of SCVs. We found that prosthetic joint infection caused by SCV staphylococci was associated with a longer duration of symptoms and more prior treatment for infection but not with an increased rate of treatment failure, compared to infection caused by normal-phenotype staphylococci.

A technique for the prevention of staphylococcal adhesion by electrical current exposure was investigated. Teflon coupons were exposed to a continuous flow of 10 3 cfu/ml Staphylococcus epidermidis with or without 2000 microA DC electrical current delivered by electrodes on opposite sides of a coupon, touching neither each other nor the coupon. A mean 3.46 (SD, 0.20) and 5.70 (SD, 1.03) log 10 cfu/cm 2 were adhered to the non-electrical current exposed coupons after 4 h and 24 h, respectively. A mean 2.46 (SD, 0.31) and 1.47 (SD, 0.73) log 10 cfu/cm 2 were adhered after 4 h and 24 h with exposure to 2000 microA electrical current delivered by graphite electrodes. A mean 2.21 (SD, 0.14) and 0.55 (SD, 0.00) log 10 cfu/cm 2 were adhered after 4 h and 24 h with exposure to 2000 microA electrical current delivered by stainless steel electrodes. Electrical current may be useful in the prevention of staphylococcal adhesion to biomaterials.

ABSTRACT The detection of pathogens associated with gastrointestinal disease may be important in certain patient populations, such as immunocompromised hosts, the critically ill, or individuals with prolonged disease that is refractory to treatment. In this study, we evaluated two commercially available multiplex panels (the FilmArray gastrointestinal [GI] panel [BioFire Diagnostics, Salt Lake City, UT] and the Luminex xTag gastrointestinal pathogen panel [GPP] [Luminex Corporation, Toronto, Canada]) using Cary-Blair stool samples ( n = 500) submitted to our laboratory for routine GI testing (e.g., culture, antigen testing, microscopy, and individual real-time PCR). At the time of this study, the prototype (non-FDA-cleared) FilmArray GI panel targeted 23 pathogens (14 bacterial, 5 viral, and 4 parasitic), and testing of 200 μl of Cary-Blair stool was recommended. In contrast, the Luminex GPP assay was FDA cleared for the detection of 11 pathogens (7 bacterial, 2 viral, and 2 parasitic), but had the capacity to identify 4 additional pathogens using a research-use-only protocol. Importantly, the Luminex assay was FDA cleared for 100 μl raw stool; however, 100 μl Cary-Blair stool was tested by the Luminex assay in this study. Among 230 prospectively collected samples, routine testing was positive for one or more GI pathogens in 19 (8.3%) samples, compared to 76 (33.0%) by the FilmArray and 69 (30.3%) by the Luminex assay. Clostridium difficile (12.6 to 13.9% prevalence) and norovirus genogroup I (GI)/GII (5.7 to 13.9% prevalence) were two of the pathogens most commonly detected by both assays among prospective samples. Sapovirus was also commonly detected (5.7% positive rate) by the FilmArray assay. Among 270 additional previously characterized samples, both multiplex panels demonstrated high sensitivity (>90%) for the majority of targets, with the exception of several pathogens, notably Aeromonas sp. (23.8%) by FilmArray and Yersinia enterocolitica (48.1%) by the Luminex assay. Interestingly, the FilmArray and Luminex panels identified mixed infections in 21.1% and 13.0% of positive prospective samples, respectively, compared to only 8.3% by routine methods.

Staphylococcus aureusis capable of causing a spectrum of human illnesses. During seriousS. aureusinfections, the staphylococcal pathogen-associated molecular patterns (PAMPs) such as peptidoglycan, lipoteichoic acid, and lipoproteins and even intactS. aureus, are believed to act in conjunction with the staphylococcal superantigens (SSAg) to activate the innate and adaptive immune system, respectively, and cause immunopathology. However, recent studies have shown that staphylococcal PAMPs could suppress inflammation by several mechanisms and protect from staphylococcal toxic shock syndrome, a life-threatening systemic disease caused by toxigenicS. aureus. Given the contradictory pro- and anti-inflammatory roles of staphylococcal PAMPs, we examined the effects ofS. aureus-derived molecular patterns on immune responses driven by SSAgin vivousing HLA-DR3 and HLA-DQ8 transgenic mice. Our study showed that neitherS. aureus-derived peptidoglycans (PGN), lipoteichoic acid (LTA), nor heat-killedStaphylococcus aureus(HKSA) inhibited SSAg-induced T cell proliferationin vitro. They failed to antagonize the immunostimulatory effects of SSAgin vivoas determined by their inability to attenuate systemic cytokine/chemokine response and reduce SSAg-induced T cell expansion. These staphylococcal PAMPs also failed to protect HLA-DR3 as well as HLA-DQ8 transgenic mice from either SSAg-induced toxic shock or pneumonia induced by a SSAg-producing strain ofS. aureus.

ABSTRACT We describe a case of shoulder hemiarthroplasty infection with Desulfovibrio legallii . Antimicrobial susceptibilities of 36 Desulfovibrio isolates are presented. Metronidazole and carbapenems exhibited reliable activity, although piperacillin-tazobactam did not. Eleven previous cases of Desulfovibrio infection are reviewed; most arose from a gastrointestinal tract-related source.

ABSTRACT A retrospective analysis of 386,706 specimens representing a variety of matrix types used in qualitative real-time PCR assays determined the overall inhibition rate to be 0.87% when the inhibition control was added preextraction to 5,613 specimens and 0.01% when the inhibition control was added postextraction but preamplification in 381,093 specimens. Inhibition rates of ≤1% were found for all specimen matrix types except urine and formalin-fixed, paraffin-embedded tissue.

ABSTRACT Streptococcus suis is an emerging swine-associated zoonotic agent that can cause meningitis and septicemia in humans. We present, to our knowledge, the first case of S. suis arthroplasty infection and streptococcal toxic shock-like syndrome due to an nonencapsulated serotype 5 strain in North America.

ABSTRACT PCR coupled with electrospray ionization mass spectrometry applied to synovial fluid specimens had an 81% sensitivity and a 95% specificity for the diagnosis of prosthetic joint infection.