STAPHYLOCOCCUS AUREUS INFECTIONS IN DIABETIC PATIENTS

Reduction in the prevalence of methicillin-resistant Staphylococcus aureus in tissue and wound swab samples taken from outpatients attending a specialist diabetic foot clinic 2005-2021

AIMS

To assess annual change in prevalence of methicillin resistant Staphylococcus aureus (MRSA) from tissue and wound swab samples from foot ulcers (DFUs) in people with diabetes between 2005 and 2021.

METHODS

A retrospective analysis of everyone with MRSA positive wound or tissue swabs taken from our specialist multidisciplinary foot clinic between July 2005 and July 2021.

RESULTS

A total of 406 MRSA positive isolates from DFU swabs were identified from 185 individuals attending the foot clinic. There were 22 hospital-acquired infections (HAIs) and 159 community-acquired infections (CAIs). Fifty-two per cent (n = 37) of these individuals from 2010 to 2021 (n = 71) had presence of at least three risk factors for MRSA. The total number of swabs sent was 6312 from 1916 individuals living with diabetes. Annual MRSA DFU prevalence peaked in 2008 at 14.6% (n = 38), decreased in 2013 to 5.2% (n = 20) and did not exceed 4% (n = 6) from 2015 to 2021. Hospital MRSA was lowest in 2021 (n = 211), a 76% fall from 2007 (n = 880). Incidence of MRSA HAI from 2015 to 2021 ranged from 5.4% (n = 14) in 2020 to 11.5% (n = 41) in 2018.

CONCLUSIONS

Prevalence of MRSA in DFU infections treated as outpatients is decreasing in line with falls in hospital acquired blood-borne infections and with overall hospital MRSA incidence. This is likely a reflection of the combination of interventions, including stringent antibiotic prescribing and decolonisation strategies. Reduction in prevalence should have positive impact on outcomes in people living with diabetes, reducing the complication of osteomyelitis and necessity for long-term antibiotic administration.

Cigarette Smoking and Peripheral Vascular Disease are Associated with Increasing Risk of ESKAPE Pathogen Infection in Diabetic Foot Ulcers

OBJECTIVE

Diabetic foot ulcers (DFUs) and ESKAPE pathogens have attracted attention globally, but the role of ESKAPE pathogens in diabetic foot infection is not well described. The purpose of this study was to evaluate the clinical features, antimicrobial resistance, and risk factors for ESKAPE infection in patients with DFUs.

METHODS

A retrospective study was conducted on 180 patients with diabetic foot infection admitted to The Affiliated Hospital of Southwest Medical University (Luzhou, China), from January 2017 to April 2021. Antimicrobial susceptibilities of all isolates were determined. Multivariate logistic regression analysis was performed to analyze the independent risk factors for ESKAPE infection, multidrug-resistant (MDR)-ESKAPE infection, MDR-pathogen infection, and severe group in patients with DFUs.

RESULTS

A total of 206 isolates were collected, of which 42.2% were ESKAPE pathogens. The independent risk factors for ESKAPE infection were cigarette smoking (OR = 1.958; 95% CI, 1.015-3.777) and peripheral vascular disease (OR = 2.096; 95% CI, 1.100-3.992), while alcohol consumption (OR = 2.172; 95% CI, 1.104-4.272) was the independent risk factor for MDR-pathogen infection. Additionally, the independent risk factors for severe DFU group were invasive treatment (OR = 326.642; 95% CI, 76.644-1392.08), the duration of systemic antibiotic treatment (OR = 0.918; 95% CI, 0.849-0.992), and length of hospital stay (OR = 1.145; 95% CI, 1.043-1.256). No independent risk factors for MDR-ESKAPE infection were found.

CONCLUSION

Our data established the microbiological features of ESKAPE pathogens and clinical manifestations of diabetic foot infection, and provide support for monitoring and management of ESKAPE infection in patients with DFUs in southwest China.

Basophil-derived IL-4 promotes cutaneous Staphylococcus aureus infection

Superficial cutaneous Staphylococcus aureus (S. aureus) infection in humans can lead to soft tissue infection, an important cause of morbidity and mortality. IL-17A production by skin TCRγδ+ cells in response to IL-1 and IL-23 produced by epithelial and immune cells is important for restraining S. aureus skin infection. How S. aureus evades this cutaneous innate immune response to establish infection is not clear. Here we show that mechanical injury of mouse skin by tape stripping predisposed mice to superficial skin infection with S. aureus. Topical application of S. aureus to tape-stripped skin caused cutaneous influx of basophils and increased Il4 expression. This basophil-derived IL-4 inhibited cutaneous IL-17A production by TCRγδ+ cells and promoted S. aureus infection of tape-stripped skin. We demonstrate that IL-4 acted on multiple checkpoints that suppress the cutaneous IL-17A response. It reduced Il1 and Il23 expression by keratinocytes, inhibited IL-1+IL-23-driven IL-17A production by TCRγδ+ cells, and impaired IL-17A-driven induction of neutrophil-attracting chemokines by keratinocytes. IL-4 receptor blockade is shown to promote Il17a expression and enhance bacterial clearance in tape-stripped mouse skin exposed to S. aureus, suggesting that it could serve as a therapeutic approach to prevent skin and soft tissue infection.

Antagonistic Interaction of Staphylococcus aureus and Staphylococcus epidermidis with Rhizopus arrhizus Mediated by Phenol Soluble Modulins and Organic Acids

Rhizopus arrhizus (R. arrhizus) is a common causative agent of mucormycosis that usually enters the human body through the respiratory tract and skin. Both these sites harbor staphylococci as a part of the normal microflora, indicating the possibility of interspecies interactions. We aimed to elucidate this interaction and identify the molecular mechanisms involved. Both Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) substantially hindered R. arrhizus radial growth, spore germination, and liquid culture biomass. Secreted components in the stationary-phase supernatant were responsible for this activity. The active components, based on molecular weight-based fractionation, mass spectrometry, and ion exclusion chromatography, were identified as a truncated version of phenol soluble modulin α2 (Δ1Δ2PSMα2) and PSMα3 in S. aureus, PSMδ in S. epidermidis, and organic acids in both the species. Exposure to the phenol soluble modulins (PSMs) extensively damaged the fungal spores and pre-existing hyphae, leading to bleb formation, shriveling, hyphal shrinkage, and cell distortion.

Risk factors for persistent methicillin-resistant Staphylococcus aureus infection in cystic fibrosis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as an important pathogen in cystic fibrosis (CF). Over 25% of individuals in the United States with CF are found to have MRSA in respiratory culture specimens, and persistent MRSA infection has been associated with more rapid decline in lung function and increased mortality. The objective of this study was to investigate clinical and demographic characteristics that are associated with the development of persistent MRSA infection in a CF population.

METHODS

This was a retrospective cohort study of individuals followed from 2002 to 2012 in the Cystic Fibrosis Foundation Patient Registry. A time-to-event analysis for the development of persistent MRSA infection was performed, and multivariable Cox proportional hazards models were constructed to identify risk factors for infection.

RESULTS

The study cohort included 19,434 individuals, of which 5844 would develop persistent MRSA infection. In the adjusted model, pancreatic insufficiency (HR: 1.49; 95% CI: 1.29-1.72), CF related diabetes (HR: 1.13; 95% CI: 1.05-1.20), co-infection with P. aeruginosa (HR: 1.21; 95% CI: 1.13-1.28), and number of hospitalizations/year (HR: 1.09; 95% CI: 1.06-1.12) were all associated with increased risk, whereas higher socio-economic status (HR: 0.87; 95% CI: 0.82-0.93) was associated with a lower risk. Receiving care at a CF center with increased MRSA prevalence was associated with increased risk of MRSA infection: highest quartile (HR: 2.33; 95% CI: 2.13-2.56).

CONCLUSIONS

No easily modifiable risk factors for persistent MRSA were identified in this study. However, several risk factors for patients at higher risk for persistent MRSA infection were identified, for example centers with a high baseline MRSA prevalence, and may be useful in designing center-specific MRSA infection prevention and control strategies and/or eradication protocols. Additional studies are needed in order to evaluate if attention to these risk factors can improve clinical outcomes.

Innate Immunity of Adipose Tissue in Rodent Models of Local and Systemic Staphylococcus aureus Infection

Background. The role of adipose tissue in systemic inflammation during bacterial infection is unclear. Effects of Staphylococcus aureus infection on adipocytes in rodent models of experimental endocarditis and peritonitis, the impact of S. aureus infection on gene expression in epididymal and subcutaneous adipose tissue, and effects of S. aureus infection on the toll-like receptor-2- (TLR2-) cathelicidin pathway in vivo and in vitro were investigated. Material and methods. The rat model of catheter-induced S. aureus endocarditis and the mouse model of S. aureus-induced peritonitis were used for infection experiments, gene expression profiling in adipose tissue, and measurement of cytokines. 3T3-L1 adipocytes were analyzed for expression of the TLR2-cathelicidin pathway. Results. Upon systemic bacterial infection by S. aureus, there is a shift from anti- to proinflammatory cytokines in serum and in adipose tissue gene expression. The TLR2-cathelicidin pathway is increasingly expressed during adipocyte differentiation in vitro and is induced upon stimulation by synthetic lipopeptides. Conclusions. Systemic infection by Gram-positive bacteria induces proinflammatory transformation of adipose tissue sites distinct from infection sites, documented on the levels of gene expression and secreted mediators. The TLR2-cathelicidine pathway is expressed and highly inducible in adipocytes in vitro. Lipopeptides are important immune-modulators of adipocytes in both gene expression and protein secretion.

The effect of diabetes mellitus on outcomes of patients with nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus: data from a prospective double-blind clinical trial comparing treatment with linezolid versus vancomycin

Background

The presence of diabetes mellitus increases the risk of several severe infections, but data on its effect on treatment outcomes in patients with nosocomial pneumonia (NP) caused by methicillin-resistant Staphylococcus aureus (MRSA) are limited.

Methods

We retrospectively analyzed data from a double-blind, randomized, multi-center, international clinical trial of culture-confirmed MRSA NP that compared treatment with linezolid to vancomycin. Specifically, we evaluated the clinical and microbiologic outcomes of patients with and without diabetes in the modified intent to treat population at end-of-treatment (EOT) and end-of-study (EOS, 7–30 days post-EOT).

Results

Among 448 enrolled patients 183 (40.8 %) had diabetes mellitus, 87 (47.5 %) of whom received linezolid and 96 (52.5 %) vancomycin. Baseline demographic and clinical characteristics were similar for the two treatment groups. Clinical success rates at EOS were 57.6 % with linezolid and 39.3 % with vancomycin, while microbiological success rates were 58.9 % with linezolid and 41.1 % with vancomycin. Among diabetic patients, rates of mortality and study drug-related adverse effects were similar between the treatment groups. Overall day 28 mortality rates were higher among diabetic patients compared to non-diabetic patients (23.5 vs 14.7 %, respectively: RD = 8.8 %, 95 % CI [1.4, 16.3]).

Conclusions

Among diabetic patients with MRSA NP, treatment with linezolid, compared to vancomycin, was associated with higher clinical and microbiologic success rates, and comparable adverse event rates.

Trial registration

NCT00084266.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1779-5) contains supplementary material, which is available to authorized users.

Iliopsoas abscess in adolescents with type 1 diabetes mellitus

Iliopsoas abscesses have been reported in adult diabetic patients, but only one case has been so far reported in the pediatric diabetic literature. We report three cases of iliopsoas abscesses in three adolescents with type 1 diabetes mellitus, suggesting that an increased awareness of this condition is required for its early recognition and prompt treatment.

Superantigen activates the gp130 receptor on adipocytes resulting in altered adipocyte metabolism

OBJECTIVE

The bacteria Staphylococcus aureus is part of the normal bacterial flora and produces a repertoire of enterotoxins which can cause food poisoning and toxic shock and might contribute to the pathogenesis of inflammatory diseases. These enterotoxins directly cross-link the T cell receptor with MHC class II, activating large amounts of T cells and are therefore called superantigens. It was recently discovered that the superantigen SEA binds to the cytokine receptor gp130. As obesity and type 2 diabetes are highly associated with inflammation of the adipose tissue and gp130 has been shown to play an important role in adipocytes, we wanted to investigate the effect of SEA on adipocyte signaling and function.

MATERIALS/METHODS

Binding of SEA to gp130 was examined using surface plasmon resonance in a cell free system. Effects of SEA on adipocyte signaling, insulin sensitivity and function were studied using western blotting and biological assays for lipolysis, lipogenesis and glucose uptake.

RESULTS

We demonstrate that SEA binds to gp130 with a medium affinity. Furthermore, SEA induces phosphorylation of a key downstream target, STAT3, in adipocytes. SEA also inhibits insulin-induced activation of PKB and PKB downstream signaling which was associated with reduced basal and insulin induced glucose uptake, reduced lipogenesis as well as reduced ability of insulin to inhibit lipolysis.

CONCLUSIONS

SEA inhibits insulin signaling as well as insulin biological responses in adipocytes supporting that bacterial infection might contribute to the development of insulin resistance and type 2 diabetes.

Obesity, diabetes and pneumonia: the menacing interface of non-communicable and infectious diseases

OBJECTIVES

To review current knowledge on the epidemiological, clinical and biological impact of the pandemic of obesity and diabetes on pneumonias.

METHODS

We conducted a literature review using PubMed and EMBASE, supplemented by various sources. Given the disparate and fragmented nature of the literature, a formal systematic review was not possible.

RESULTS

In 2008, globally 10% of men and 14% of women were obese and an estimated 371 million had diabetes; half undiagnosed and many obese. Numbers are rising rapidly in low- and middle-income countries where the majority reside, but reliable data are lacking. The most frequent pneumonias in obesity and diabetes are tuberculosis, influenza and pneumococcal, staphylococcal and opportunistic pathogens. Diabetes impacts tuberculosis control and increases drug resistance and mortality. Mortality and morbidity from pneumococcal pneumonia and influenza are increased in obesity and diabetes. In addition to mechanical and physiological effects, there are considerable immunological abnormalities characterised by chronic, low-grade inflammation. Simultaneous up-regulation and dysregulation of both innate and adaptive immune responses impair control and killing of invading organisms. Prevention in those at risk is poorly practised, although screening for tuberculosis in diabetes is beginning in high-burden settings.

CONCLUSIONS

Pneumonia is a threat globally in obesity and diabetes with increased incidence and severity of disease. There is uncertainty about whether vaccines are equally effective in those with obesity and diabetes. Increased epidemiological, clinical and biological knowledge will be crucial to face this 21st century challenge.

Evaluation of the Combined Effects of Stilbenoid from Shorea gibbosa and Vancomycin against Methicillin-Resistant Staphylococcus aureus (MRSA)

The aim of this study is to determine the combined effects of stilbenoids from Shorea gibbosa and vancomycin against methicillin-resistant Staphylococcus aureus (MRSA). A total of nine pure compounds, five stilbenoid dimers ε-viniferin, ampelopsin A, balanocarpol, laevifonol and diptoindonesin G and four stilbenoid trimers α-viniferin, johorenol A, ampelopsin E and vaticanol G were evaluated for their antibacterial activities against ATCC 33591 and a HUKM clinical isolate. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each active compound were determined using the serial microdilution and plate-streak techniques. The combined effect of stilbenoids with vancomycin against MRSA was evaluated using the checkerboard assay to determine their fractional inhibitory concentration (FIC) index values. The MIC value of α-viniferin on both MRSA strains was 100 μg/mL, whereas those of johorenol A on ATCC 33591 and HUKM strain were 100 μg/mL and 200 μg/mL, respectively. The MIC values of ampelopsin E and vaticanol G were higher than 400 μg/mL. Out of the five stilbenoid dimers, only ε-viniferin was capable of inhibiting the growth of both MRSA strains at MIC 400 μg/mL. The MBC value of ε-viniferin, α-viniferin and johorenol A showed bacteriostatic action against MRSA. The FIC index value of ε-viniferin and α-viniferin in combination with vancomycin showed an additive effect (0.5 < FIC ≤ 2.0) against both MRSA strains. Johorenol A-vancomycin combination was also additive against HUKM strain, but it showed synergistic interaction with vancomycin against ATCC 33591 (FIC < 0.5). Stilbenoid compounds from Shorea gibbosa have anti-MRSA activity and huge potential as an alternative phytotherapy in combating MRSA infections.

Skin signs of systemic diseases

The skin should not be considered as an isolated organ but rather as a definite functioning system that communicates with the internal environment. Skin signs of systemic diseases occur frequently and sometimes feature the first symptoms of an internal disease; furthermore, these manifestations may be the sole expressions of otherwise asymptomatic systemic disorders. A number of dermatologic signs, symptoms, and disorders can be invaluable as markers of systemic disease. Although a plethora of specialized modern diagnostic tests are available, the skin still remains the only organ of the body that is immediately and completely accessible to direct clinical examination. This contribution reviews the skin signs of systemic diseases. The description of the clinical features of skin lesions observed in several internal diseases will be useful to general physicians, internists, and dermatologists in the diagnosis of a systemic disease.

Intracellular survival of Staphylococcus aureus in adipocyte-like differentiated 3T3-L1 cells is glucose dependent and alters cytokine, chemokine, and adipokine secretion

Although obesity and type 2 diabetes mellitus are associated with Gram-positive infections and a worse clinical outcome, it is unknown whether adipocytes can be infected by Gram-positive bacteria. Adipocyte-like differentiated 3T3-L1 cells and Staphylococcus aureus were used for infection experiments under normoglycemic (100 mg/dl) and hyperglycemic (450 mg/dl) conditions in the presence/absence of insulin (1 μm). Intracellular presence and survival of S. aureus was investigated quantitatively. Supernatant cytokines, chemokines, and adipokines were measured by ELISA. Lipid metabolism and cellular morphology of infected adipocytes were investigated by different techniques. The present study provides the proof of principle that adipocyte-like cells can be infected by S. aureus dose dependently for up to 5 d. Importantly, low bacterial inocula did not affect cell viability. Intracellular survival of S. aureus was glucose dependent but not insulin dependent, and insulin receptor expression and insulin receptor signaling were not altered. Infection increased macrophage chemoattractant protein-1, visfatin, and IL-6 secretion, whereas resistin and adiponectin were decreased. Infected adipocytes had higher intracellular triacylglycerol concentrations and larger lipid droplets because of a decreased lipolysis. Taken together, infection of adipocytes by S. aureus is glucose dependent, inhibits cellular lipolysis, and affects the secretion of immunomodulating adipokines differentially. Because cell viability is not affected during infection, adipose tissue might function as a host for chronic infection by bacteria-causing metabolic, proinflammatory, and prodiabetic disturbances.

Reduced neutrophil apoptosis in diabetic mice during staphylococcal infection leads to prolonged Tnfα production and reduced neutrophil clearance

Diabetes is a frequent underlying medical condition among individuals with Staphylococcus aureus infections, and diabetic patients often suffer from chronic inflammation and prolonged infections. Neutrophils are the most abundant inflammatory cells during the early stages of bacterial diseases, and previous studies have reported deficiencies in neutrophil function in diabetic hosts. We challenged age-matched hyperglycemic and normoglycemic NOD mice intraperitoneally with S. aureus and evaluated the fate of neutrophils recruited to the peritoneal cavity. Neutrophils were more abundant in the peritoneal fluids of infected diabetic mice by 48 h after bacterial inoculation, and they showed prolonged viability ex vivo compared to neutrophils from infected nondiabetic mice. These differences correlated with reduced apoptosis of neutrophils from diabetic mice and were dependent upon the presence of S. aureus and a functional neutrophil respiratory burst. Decreased apoptosis correlated with impaired clearance of neutrophils by macrophages both in vitro and in vivo and prolonged production of proinflammatory tumor necrosis factor alpha by neutrophils from diabetic mice. Our results suggest that defects in neutrophil apoptosis may contribute to the chronic inflammation and the inability to clear staphylococcal infections observed in diabetic patients.

Clinical characteristics and outcomes of diabetic patients with Staphylococcus aureus bacteremia and endocarditis

The complications from S. aureus bacteremia (SAB) and infective endocarditis (SAIE) are higher in patients with diabetes. We summarize the characteristics and outcome of diabetic patients enrolled in a multicenter trial of daptomycin vs. standard therapy for SAB and SAIE. Adult patients with SAB were randomized to daptomycin 6 mg/kg/day or standard therapy (vancomycin 1 g every 12 h or antistaphylococcal penicillin 2 g every 4 h, both with gentamicin 1 mg/kg every 8 h for 4 days). Clinical success was defined as survival, resolution of S. aureus infection, and clinical outcome of cure or improved 6 weeks after end of therapy. Diabetic patients (86/235) were older, more overweight, and were more likely to present with systemic inflammatory response syndrome (SIRS) and to have complicated SAB. Clinical success rates were similar (67.4% in diabetics and 70.5% in non-diabetics). The mortality rate was significantly higher among diabetic patients (22.1% vs. 11.4%, p = 0.038). In the diabetes subgroup, the clinical success and mortality rates were comparable between the daptomycin and the standard therapy arms. The presence of diabetes is associated with significantly higher mortality in patients with SAB and SAIE. Daptomycin is an alternative therapeutic option in diabetic patients with these serious staphylococcal infections.

Staphylococcus aureus nasal carriage might be associated with vitamin D receptor polymorphisms in type 1 diabetes

BACKGROUND

Polymorphisms in the vitamin D receptor (VDR) gene have been associated with susceptibility to several diseases, including type 1 diabetes (T1D) and infections. In this study we investigated whether VDR gene polymorphisms influence nasal carriage of Staphylococcus aureus in individuals with T1D.

METHODS

In 93 T1D patients, VDR polymorphisms on FokI F>f, BsmI B>b, ApaI A>a, and TaqI T>t were determined in DNA extracted from peripheral blood leukocytes, and a nasal swab was obtained to detect colonization by S. aureus. A repeat swab was obtained in 76/93 subjects for the estimation of persistent S. aureus carriage.

RESULTS

The prevalence of S. aureus nasal colonization was 31.2% and the prevalence of persistent carriage was 25%. The presence of TaqI T allele was related to higher rates of S. aureus colonization, and TaqI TT homozygotes were more colonized (48.5% vs. 21.7%; p 0.007; OR 3.40, 95% CI 1.36-8.52) and more persistent carriers (37.9% vs. 17.0%; p 0.039; OR 2.98, 95% CI 1.02-8.67). The presence of ApaI A allele was related to lower rates of S. aureus colonization, and ApaI AA homozygotes were less colonized (17.6% vs. 39.0%; p 0.026; OR 0.34, 95% CI 0.12-0.94) and less persistent carriers (11.5% vs. 32%; p 0.043; OR 0.28, 95% CI 0.07-1.06). No differences were observed for BsmI and FokI genotypes.

CONCLUSIONS

Our findings suggest that VDR polymorphisms may be associated with nasal carriage of S. aureus in individuals with T1D, and further contribute to the better understanding of the immunomodulatory role of vitamin D in the human host's response and susceptibility to infection.

Increased oxacillin resistance in thigh pyomyositis in diabetic patients

Thigh abscesses due to pyomyositis are uncommon. To guide empiric antibiotic therapy in diabetics we determined the rate of such infections due to oxacillin-resistant Staphylococcus aureus and Gram-negative organism infections, and whether the occurrence of oxacillin-resistant pathogens increased during the study period. We retrospectively reviewed 39 adult patients with diabetes mellitus treated for a deep thigh abscess. There were 29 men and 10 women; their mean age was 45 years. Comorbidities were present in 15 patients. S. aureus was the most common pathogen, present in 82% (32/39) of our patients. Gram-negative organisms were cultured in 14% (6/39) of patients and anaerobes in 10% (4/39). The infection was polymicrobial in 12 of 39 patients (31%). Oxacillin-resistant S. aureus comprised 25% (8/32) of infections due to S. aureus. Oxacillin-resistance increased during the last 3 years of this study from one of 18 S. aureus isolates from 1994 to 2004 to seven of 14 isolates from 2004 to 2006. In diabetic patients with thigh pyomyositis, empiric antibiotic therapy should provide broad spectrum coverage for oxacillin-resistant S. aureus, Gram-negative, as well as anaerobic organisms.

LEVEL OF EVIDENCE

Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Conjunctival flora in patients with type 1 or type 2 diabetes mellitus

Patients with diabetes mellitus (DM) are prone to infection because glucose in the skin, urine, mucous membranes, and tears promotes growth of microorganisms. Conjunctival flora develops soon after birth, and some saprophytic conjunctival flora play a pathogenic role when immune function is compromised, which can lead to serious infection. DM is one condition that may compromise immune status. In lacrimal function tests of DM patients, a decrease in breakup time (BUT) of lacrimal film and a decrease in Schirmer's test results were seen. In the present study, conjunctival flora in patients with DM was compared with that in controls with regard to type and duration of diabetes and results of lacrimal function tests. Seventeen patients with type 1 DM (n=34 eyes), 66 patients with type 2 DM (n=132 eyes), and 50 control subjects (n=100 eyes) were included. The control group consisted of age-matched patients with no ophthalmologic problems other than refractive error. Glycosylated hemoglobin values were measured with highpressure liquid chromatography with the Hi-AUTOA1c analyzer (Kyoto Daiichi Kagatu Co., Ltd., Kyoto, Japan). Type and duration of diabetes and demographic data were recorded, and routine ophthalmologic examinations were performed; the BUT of lacrimal film was determined, and the results of Schirmer's test were assessed. Microbiologic sampling was performed twice for both eyes with sterile cotton swabs. One sample was incubated in 2 mL of brain-heart infusion broth agar; the other was incubated for the presence of fungi in Sabouraud dextrose agar. Colony morphology, hemolysis, and Gram's stain, as well as catalase, oxidase, and coagulase tests were performed. No growth was observed in 12 of 17 patients (35.4%) with type 1 DM, 28 of 66 patients (21.2%) with type 2 DM, and 25 of 50 control subjects (50%). Staphylococcus epidermidis (11.79%) and Staphylococcus aureus (11.7%) were the most frequently isolated organisms in the type 1 DM group, and S epidermidis (24.2%) and S aureus (21.2%) were the predominant organisms in the type 2 DM group. In control subjects, S epidermidis (22%), S aureus (12%), and Corynebacterium spp (10%) were the most frequently isolated organisms, and the number of eyes with growth of S aureus was significantly higher in the type 2 DM group than in the other groups (P<.01). Patients with diabetes are more prone to postoperative endophthalmitis than are nondiabetics, and preoperative application of antiseptic or antimicrobial agents to the conjunctiva may not sterilize the area. Impaired integrity of the posterior capsule may also increase the risk of endophthalmitis. Postoperative endophthalmitis is usually associated with gram-positive organisms (75%-80%); gram-negative organisms (15%-29%) and fungi (3%-13%) account for a smaller number of cases. A high rate of resistance to penicillin, ampicillin, and tetracycline was observed in S aureus isolates, although resistance to vancomycin was absent, rendering this molecule the most effective therapeutic option. In this study, S epidermidis and S aureus were the 2 most frequently isolated organisms in patients with DM. It is concluded that the conjunctival flora in diabetic subjects differs from that in nondiabetic subjects. This should be considered preoperatively and postoperatively, and prophylactic and postoperative treatment should be administered accordingly to diabetic patients.

The evidence base for the efficacy of antibiotic prophylaxis in dental practice

INTRODUCTION

People with various medical conditions and devices are suggested candidates for receiving antibiotic prophylaxis before undergoing dental procedures. This practice is controversial, however, owing to the lack of proof of efficacy. The authors conducted a qualitative, systematic review to determine the level of evidence for this practice and whether antibiotic prophylaxis prevents distant site infections in these patients.

METHODS

The authors selected eight groups of patients with specific medical conditions and devices who often are given antibiotic prophylaxis before undergoing invasive dental procedures. The conditions and devices were cardiac-native heart valve disease, prosthetic heart valves and pacemakers; hip, knee and shoulder prosthetic joints; renal dialysis shunts; cerebrospinal fluid shunts; vascular grafts; immunosuppression secondary to cancer and cancer chemotherapy; systemic lupus erythematosus; and insulin-dependent (type 1) diabetes mellitus. The authors thoroughly searched the literature for the years 1966 through 2005 for references indicating some level of support for this practice and graded each publication on the basis of level of evidence.

RESULTS

The authors found formal recommendations in favor of antibiotic prophylaxis for only three of the eight medical conditions: native heart disease, prosthetic heart valves and prosthetic joints. They found no prospective randomized clinical trials and only one clinical study of antibiotic prophylaxis. Only one systematic review and two case series provided weak, if any, support for antibiotic prophylaxis in patients with cardiac conditions. The authors found little or no evidence to support this practice or to demonstrate that it prevents distant site infections for any of these eight groups of patients.

CONCLUSIONS

No definitive, scientific basis exists for the use of prophylactic antibiotics before dental procedures for these eight groups of patients.

Aspirin Treatment Is Associated With a Significantly Decreased Risk of Staphylococcus aureus Bacteremia in Hemodialysis Patients With Tunneled Catheters

BACKGROUND

Hemodialysis patients with tunneled catheters are at increased risk of bacteremic Staphylococcus aureus infections. In vitro and in vivo studies showed that aspirin has direct antistaphylococcal effects by inhibiting expression of alpha-toxin and matrix adhesion genes through activation of sigma factor B stress-induced operon. We hypothesized that long-term treatment with aspirin may decrease the frequency of S aureus bacteremia in such patients.

METHODS

We retrospectively analyzed electronic medical records for a variety of clinical parameters, including catheter dwell times, blood culture results, and aspirin use in our dialysis population.

RESULTS

A total of 4,722 blood cultures were performed in 872 patients during more than 476 patient-catheter-years. There was a lower rate of catheter-associated S aureus bacteremia in patients treated with aspirin versus those not treated with aspirin (0.17 versus 0.34 events/patient-catheter-year, P = 0.003), whereas no such difference was observed for other bacteria. This association was dose dependent, seen mostly with the 325-mg aspirin dose. Using the Cox proportional hazard method, risk to develop a first episode of S aureus bacteremia decreased by 54% in patients using aspirin (confidence interval, 24 to 72; P = 0.002). Aspirin was associated with decreased risk of: (1) a first episode of methicillin-resistant S aureus bacteremia and (2) metastatic complications during the first episode of catheter-related S aureus bacteremia.

CONCLUSION

These data are consistent with our clinical hypothesis that aspirin has a clinically useful antistaphylococcal effect in the dialysis population.

Clinical and epidemiologic characteristics cannot distinguish community-associated methicillin-resistant Staphylococcus aureus infection from methicillin-susceptible S. aureus infection: a prospective investigation

BACKGROUND

Community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) infection has become common worldwide. Some researchers have argued that empirical therapy for MRSA should be given only to patients with suspected CA S. aureus infections who have risk factors for acquisition of MRSA. However, there are no prospective data examining this approach.

METHODS

We prospectively enrolled consecutive patients who were hospitalized with S. aureus infection, administered a detailed questionnaire, and collected clinical and microbiological information.

RESULTS

Of the 280 consenting patients, 180 were adults with CA S. aureus infection. Among these subjects, 108 (60%) had MRSA infection, and 78 (40%) had methicillin-susceptible S. aureus (MSSA) infection. MRSA infection was associated with younger age (P<.0001); skin/soft-tissue infection (P=.015); snorting/smoking illegal drugs (P=.01); recent incarceration (P=.03); lower comorbidity index (P=.01); more frequent visits to bars, raves, and/or clubs (P=.03); and higher frequency of laundering clothes in hot water (P=.05). However, the sensitivity, specificity, and predictive values for these factors for discriminating CA-MRSA infection from CA-MSSA infection were relatively poor. Post-hoc modeling revealed that, even in a 10% (i.e., low) MRSA prevalence population, patients lacking the 3 strongest MRSA risk factors would still have a 7% posttest probability of MRSA. Most MRSA strains belonged to the ST-8/USA300 genotype, contained SCCmec type IV, and shared virulence factors commonly found in the ST1:USA400 clone. MSSA strains were genotypically heterogeneous.

CONCLUSIONS

We found that clinical and epidemiological risk factors in persons hospitalized for CA S. aureus infection cannot reliably distinguish between MRSA and MSSA. Our findings have important implications for the choice of empirical antibiotic therapy for suspected S. aureus infections and for infection control.

Common infections in diabetes: pathogenesis, management and relationship to glycaemic control

Specific defects in innate and adaptive immune function have been identified in diabetic patients in a range of in vitro studies. However, the relevance of these findings to the integrated response to infection in vivo remains unclear, especially in patients with good glycaemic control. Vaccine efficacy seems adequate in most diabetic patients, but those with type 1 diabetes and high glycosylated haemoglobin levels are most likely to exhibit hypo-responsiveness. While particular infections are closely associated with diabetes, this is usually in the context of extreme metabolic disturbances such as ketoacidosis. The link between glycaemic control and the risk of common community-acquired infections is less well established but could be clarified if infection data from large community-based observational or intervention studies were available. The relationship between hospital-acquired infections and diabetes is well recognized, particularly among post-operative cardiac and critically ill surgical patients in whom intensive insulin therapy improves clinical outcome independent of glycaemia. Nevertheless, further research is needed to improve our understanding of the role of diabetes and glycaemic control in the pathogenesis and management of community- and hospital-acquired infections.

Tropical dermatology: bacterial tropical diseases

Bacterial infections are common in tropical parts of the world and can include those species also seen regularly in temperate climates. Many tropical bacterial infections, however, are rarely diagnosed in temperate parts of the world and include bartonellosis, tropical ulcer, tropical pyomyositis, granuloma inguinale, lymphogranuloma venereum, yaws, pinta, melioidosis, and glanders. Some tropical bacterial diseases, eg, plague and anthrax, are associated with high mortality rates and are of potential use in bioterrorism. Some tropical bacterial diseases are closely associated with specific activities such as hunting (ie, tularemia) or eating raw seafood (Vibrio vulnificus infection). The bacterial diseases having the most severe medical impact in the tropics are those caused by members of the Mycobacterium genus. Millions of persons throughout the world suffer from tuberculosis and leprosy; Buruli ulcers are common causes of morbidity in many tropical countries. Because of the increasing frequency of travel to tropical parts of the world for tourism and work as well as the increasing number of immigrants and adoptees from these areas, it is imperative that physicians practicing in temperate climates be able to recognize the signs and symptoms of tropical bacterial diseases, carry out the proper diagnostic tests, and initiate appropriate therapy and prevention.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be familiar with the clinical presentations, epidemiologies, diagnoses, therapies, and preventions of bacterial tropical diseases.

Diagnosis and treatment of diabetic foot infections

Diabetic foot infections frequently cause morbidity, hospitalization, and amputations. Gram-positive cocci, especially staphylococci and also streptococci, are the predominant pathogens. Chronic or previously treated wounds often yield several microbes on culture, including gram-negative bacilli and anaerobes. Optimal culture specimens are wound tissue taken after debridement. Infection of a wound is defined clinically by the presence of purulent discharge or inflammation; systemic signs and symptoms are often lacking. Only infected wounds require antibiotic therapy, and the agents, route, and duration are predicated on the severity of infection. Mild to moderate infections can usually be treated in the outpatient setting with oral agents; severe infections require hospitalization and parenteral therapy. Empirical therapy must cover gram-positive cocci and should be broad spectrum for severe infections. Definitive therapy depends on culture results and the clinical response. Bone infection is particularly difficult to treat and often requires surgery. Several adjuvant agents may be beneficial in some cases.

Impaired primary immune response in type-1 diabetes: results from a controlled vaccination study

Patients with diabetes have an increased risk for infections, but information on their adoptive immunity is incomplete and contradictory. Twenty patients with diabetes type-1 and 20 patients with type-2 diabetes were vaccinated with T-cell-dependent primary protein antigens (hepatitis A viral antigen, HAV; diphtheria toxoid) and a T-cell-independent polysaccharide antigen (pneumococcal polysaccharide). In parallel, the proliferative response of CD4+ T-cells to the primary protein antigens keyhole limpet hemocyanin (KLH) and sperm whale myoglobin (SWM) was measured in vitro using monocyte-derived dendritic cells (MDDC) as antigen-presenting cells. Compared to healthy controls, type-1 diabetes patients mounted a significantly impaired primary antibody response to hepatitis A vaccine (median HAV antibody titer after the first vaccination, 53 IU/L in diabetic patients vs 212 IU/L in the controls, P = 0.017) and diphtheria toxoid (median serum antibodies after vaccination, patients, 0.94 IU/ml, controls, 6.38 IU/ml, P = 0.004), while the response to pneumococcal polysaccharide was normal. Type-2 diabetes patients had a comparable metabolic dysregulation but showed a normal antibody response following vaccination, demonstrating that the effect was not due to hyperglycemia. Antigen-induced interferon-gamma and interleukin-13 release was reduced in type-1 diabetes patients, localizing the impairment to the level of antigen-presenting cell-T-cell interaction. In addition, the proliferative response of CD4+ T-cells derived from type-1 diabetes patients to KLH and SWM was significantly reduced (P < or = 0.01). FACS analysis of CD80 (B7.1), CD86 (B7.2), and HLA-DR expression on MDDC could not demonstrate significant differences in the expression of these molecules between type-1 and type-2 diabetes patients and healthy controls. An association of low HAV antibody response with HLA-DR3,4 expression in the patients was shown. Our results indicate that the primary antibody response to T-cell dependent antigens as well as the T-cell response to primary protein antigens is reduced in type-1 diabetes patients and that additional booster immunization can overcome the defect.

Imaging of fungal, viral, and parasitic musculoskeletal and spinal diseases

There are many nonbacterial infections that have musculoskeletal manifestations and radiologic findings. These infections produce a limited range of tissue responses, depending on the organism, the tissue compartment affected, and the immune competence of the host. Diagnosis is dependent on obtaining an appropriate travel or geographic history, the clinical and laboratory features, and on occasion the specific radiologic findings.

Risk factors for colonization with methicillin-resistant Staphylococcus aureus among nursing home residents

Risk factors predictive of methicillin-resistant Staphylococcus aureus (MRSA) colonization in 786 of 910 nursing home residents were evaluated. A customized questionnaire was completed by theresidents, who were screened for MRSA. The risk factors significantly associated with MRSA colonization were male sex, age >80 years, residence in the nursing home for <six months, hospitalization during the previous 6 months, peripheral vascular disease, pressure sores, steroid therapy, poor general skin condition, antibiotic therapy during the previous three months and a mental test score of O14. Multivariate analysis identified male sex and pressure sores as independent variables.

Osteoarticular disorders of endocrine origin

Endocrine diseases may present with musculoskeletal complaints, and their outcome, even after endocrine control, can be impaired by bone and joint disorders. All musculoskeletal structures, including bone, cartilage, synovium, tendons and ligaments, can be involved by some processes triggered by the endocrine disorder and its related disturbances of homeostasis, including that of growth factors. Endocrine disorders may account for 20-30% of all cases of osteopenia or osteoporosis in adults, the main causes being central and peripheral hypogonadism, endogenous and exogenous hypercorticism or hyperthyroidism, and primary hyperparathyroidism. The physician should be aware of these identifiable and treatable causes of bone loss when interpreting bone mineral density measurements. It is also valuable to evaluate bone status in patients diagnosed with these endocrine disorders. Specific bone therapeutic measures could be discussed. Other frequent musculoskeletal features include myopathy and joint and soft tissue involvement. Endocrine myopathy is frequent in most of the endocrine disorders and is non-specific since proximal painless muscle weakness associated with normal serum enzyme levels and an uncommonly encountered electromyogram myopathic pattern are present in these diseases. Soft tissue involvement is also a frequent consequence of acromegaly, hypothyroidism and diabetes mellitus. There is also a risk of nerve entrapment syndromes in these conditions. Specific arthropathies are the hallmark of acromegaly at the spinal and peripheral joints. Neuroarthropathies are a severe complication of diabetes mellitus as a result of infection, neuropathy and vasculopathy. In all these settings, the physician should be aware that endocrine disorders are part of the differential diagnosis and, conversely, that these articular and peri-articular lesions should be managed independently of the control of the underlying endocrine condition, a specific outcome being borne in mind.

Septicemia in diabetic hemodialysis patients: comparison of incidence, risk factors, and mortality with nondiabetic hemodialysis patients

Diabetes mellitus is the most common cause of treated end-stage renal disease (ESRD), and diabetic hemodialysis patients have a high mortality rate. To identify differences in risk of septicemia among diabetic and nondiabetic hemodialysis patients, we examined the incidence, risk factors, and mortality for septicemia in a large sample of the US hemodialysis population. We performed a longitudinal cohort study of the incidence and risk factors for hospitalized cases of septicemia in diabetic and nondiabetic hemodialysis patients using baseline data from the US Renal Data System case-mix severity study with 7-year follow-up from hospitalization and death records. Independent risk factors for septicemia were assessed using Poisson regression. Independent effect of septicemia on mortality was assessed using Cox proportional hazards analysis. Over 7 years, 11.1% of nondiabetic patients and 12.5% of diabetic patients experienced at least one episode of septicemia. Older age and low serum albumin were independent risk factors for septicemia in all patients. In diabetics, white race, peripheral vascular disease, and hemodialyzer reuse, particularly in type 1, were independent risk factors. In nondiabetics, coronary artery disease, cerebrovascular disease, and temporary and permanent catheters were associated with an increased risk. In both groups, patients who experienced an episode of septicemia had twice the risk of death from any cause and an eightfold risk of death from septicemia. Septicemia occurs equally frequently and carries a marked increased risk of death in both nondiabetic and diabetic hemodialysis patients. Improving nutritional status and minimizing the use of catheters might help ameliorate the risk of septicemia. In diabetics, aggressive treatment of peripheral vascular disease might help reduce the risk of septicemia. Further research to elucidate potential mechanisms for variations in risk for septicemia according to race and hemodialyzer reuse practices are warranted in diabetic patients.

Unusual case of septic arthritis of the hip: spread from adjacent adductor pyomyositis

Distinguishing intracapsular and extracapsular hip infections may be clinically difficult. Because of this difficulty in diagnosis, the spread of an extracapsular infection into the hip joint may be missed and lead to significant joint destruction. The case of a patient who suffered from the spread of adductor pyomyositis to the hip joint is reported. The delay in diagnosis of an intracapsular hip infection led to significant intra-articular destruction and ultimately necessitated a Girdlestone resection arthroplasty. The patient's hip function was salvaged with a total hip arthroplasty. The presence of an extracapsular hip infection should mandate serial physical examinations and aggressive evaluation to rule out intracapsular spread. A delay in diagnosis of an intracapsular hip infection can lead to catastrophic results.

Pyomyositis

A case of non-tropical pyomyositis (PM), in a 63-year-old female patient, affecting gluteus and intrapelvic muscles is presented. Delayed diagnosis and treatment led to long-standing morbidity. Magnetic resonance imaging (MRI) of the pelvis provided valuable information on the nature and extent of the disease and helped to plan surgical management. MRI of the pelvis should be undertaken at an early-stage. Prompt examination of material obtained by aspiration or debridement would then permit an accurate diagnosis and appropriate management.