Native valve staphylococcal endocarditis: etiology, risk factors and outcome in 53 cases

Non-nosocomial healthcare-associated infective endocarditis in Taiwan: an underrecognized disease with poor outcome

BACKGROUND

Non-nosocomial healthcare-associated infective endocarditis (NNHCA-IE) is a new category of IE of increasing importance. This study described the clinical and microbiological characteristics and outcome of NNHCA-IE in Taiwan.

METHODS

A retrospective study was conducted of all patients with IE admitted to the Kaohsiung Veterans General Hospital in Kaohsiung, Taiwan over a five-year period from July 2004 to July 2009. The clinical and microbiological features of NNHCA-IE were compared to those of community-acquired and nosocomial IE. Predictors for in-hospital death were determined.

RESULTS

Two-hundred episodes of confirmed IE occurred during the study period. These included 148 (74%) community-acquired, 30 (15%) non-nosocomial healthcare-associated, and 22 (11%) nosocomial healthcare-associated IE. Staphylococcus aureus was the most frequent pathogen. Patients with NNHCA-IE compared to community-acquired IE, were older (median age, 67 vs. 44, years, p < 0.001), had more MRSA (43.3% vs. 9.5%, p < 0.001), more comorbidity conditions (median Charlson comorbidity index [interquartile range], 4[2-6] vs. 0[0-1], p < 0.001), a higher in-hospital mortality (50.0% vs. 17.6%, p < 0.001) and were less frequently recognized by clinicians on admission (16.7% vs. 47.7%, p = 0.002). The overall in-hospital mortality rate for all patients with IE was 25%. Shock was the strongest risk factor for in-hospital death (odds ratio 7.8, 95% confidence interval 2.4-25.2, p < 0.001).

CONCLUSIONS

NNHCA-IE is underrecognized and carries a high mortality rate. Early recognition is crucial to provide optimal management and improve outcome.

The serological diagnosis of staphylococcal infective endocarditis

OBJECTIVES

Establishing the diagnosis of infective endocarditis (IE) can be difficult when blood cultures remain sterile or echocardiography is inconclusive. Staphylococcus aureus is a common aetiological microorganism in IE and is associated with severe valvular destruction and increased mortality. Early diagnosis using culture and antibiotic independent tests would be preferable to allow prompt antibiotic administration. We have developed and evaluated 2 serological assays for the rapid identification of a staphylococcal aetiology in infective endocarditis. The assays measure IgG against whole cells of S. aureus and IgG against lipid S, a novel extracellular antigen released by Gram-positive microorganisms.

METHODS

Serum was collected from 130 patients with IE and 94 control patients. IgG against whole cells of S. aureus and against lipid S was measured by enzyme linked immunosorbent assay (ELISA).

RESULTS

Anti-lipid S IgG titres were higher in IE caused by Gram-positive microorganisms than in controls (p<0.0001) and higher in staphylococcal IE than in both controls and IE caused by other microorganisms (p=0.0003). Anti-whole cell staphylococcal IgG was significantly higher in serum from patients with staphylococcal IE than in IE caused by other microorganisms and control samples (p<0.0001).

CONCLUSION

High anti-whole cell IgG titres are predictive of a staphylococcal aetiology in IE. Elevated serum anti-lipid S IgG titres are predictive of Gram-positive infection compared to controls, very high titres being associated with staphylococcal IE.

Endocarditis due to Staphylococcus aureus after minor dog bite

Living in a society of animal lovers, the dangers are often not always apparent. Injury from bites and scratches is an occupational hazard for those people who work with animals. Despite the high risk of secondary wound infection as a result of an animal bite, many patients do not receive treatment with an antimicrobial medication. This report describes a case of a previously fit and well 66-year-old female dog handler who, after an apparently minor dog bite to the hand, developed fulminant acute Staphylococcus aureus endocarditis and life-threatening aortic regurgitation. This article discusses the microbiology behind dog bites and highlights the need for proper wound hygiene and consideration of prophylactic broad-spectrum antibiotics to prevent potentially fatal outcomes as a result of what initially seem to be minor injuries.

Atopic eczema and staphylococcal endocarditis: time to recognize an association?

An 18-year-old man presented with a 3-day history of malaise, pyrexia, confusion and left knee pain. He had a history of atopic eczema since the age of 6 months but was otherwise well. He had worn a dental brace for the past 2 years without complications and had no recent dental intervention. There was no history of intravenous drug abuse.

On examination he was pyrexial at 39.0°C, clinically dehydrated, with a sinus tachycardia of 100 beats per minute and a systemic blood pressure of 130/80 mmHg. He had eczematous lesions on his face, arms and legs. Auscultation revealed no cardiac murmurs and lung fields were clear. There were no stigmata of endocarditis. He was mentally obtunded with a Glasgow Coma Score of 14/15 but had no other neurological signs. The left knee demonstrated a full range of movement and no obvious effusion. Orthopaedic opinion was of a reactive arthritis.

Chest and left knee radiography was unremarkable. C-reactive protein (CRP) was elevated at 251mg/litre, haemoglobin was 12.4g/dl, leukocytes 11.7×109/litre (with 89% neutrophils) and platelets 26×109/litre. A screen for disseminated intravascular coagulopathy was negative. He was hyponatraemic (sodium 125 mmol/litre) and mildly uraemic (urea 7.8 mmol/litre, creatinine 91μmol/litre).

Blood cultures grew Staphylococcus aureus sensitive to flucloxacillin and gentamicin. Computed tomography (CT) of the brain showed generalized cerebral swelling with effacement of the basal cisterns, but no focal abnormality. Treatment was initiated with intravenous flucloxacillin, gentamicin and fluid replacement.

The following day he developed severe pulmonary oedema and haemodynamic compromise necessitating admission to the intensive care unit for inotropic support and ventilation. Urgent transoesophageal echocardiography showed a 2x2 cm vegetation on the anterior mitral valve leaflet (Figure 1) with marked prolapse and severe mitral regurgitation. There was systolic flow reversal in the pulmonary veins. Left atrial size was normal and left ventricular function good.

He underwent emergency mitral valve replacement with a St Jude mechanical valve (St Jude Medical Inc, St Paul, Minnesota, USA). At operation there was seen to be almost complete destruction of the anterior mitral valve leaflet. His postoperative recovery was good, completing 6 weeks of antibiotic therapy, and repeat CT showed resolution of the cerebral oedema. During the admission he experienced an exacerbation of his eczema and was treated with topical steroids and emollients by the dermatologists.