DP Ghadage, AM Bal 
Department of Microbiology, BJ Medical College, Pune

Salmonellae are a rare cause of infective endocarditis. We report a case in which Salmonella enterica serotype Worthington was isolated from a case of endocarditis. The isolate was resistant to ampicillin, gentamicin, amikacin and chloramphenicol and sensitive to ciprofloxacin and cefotaxime. (Indian Heart J 2001; 53: 350–351)

Key Words: Infection, Endocarditis, Heart diseases

Endocarditis due to nontyphoidal Salmonella is a rare clinical entity and is associated with a high mortality rate. Approximately 75% of cases suffering from this condition have an underlying cardiac abnormality such as rheumatic heart disease and congenital heart defects.¹ We report a case where an unusual serotype of Salmonella was isolated from a case of infective endocarditis in a patient with a predisposing valvular abnormality. 

Case Report

A 21-year-old woman was admitted with complaints of fever, anorexia and general weakness of 15 days’ uration.The patient had been suffering from aortic stenosis with mitral valve prolapse for 10 years. There was no history of cough, breathlessness, hemoptysis and palpitations. On examination, the patient was found to be febrile (101°F). There was no edema, cyanosis, clubbing or icterus. Her blood pressure was 110/80 mmHg, jugular venous pressure was normal and bilateral carotid thrill was present. An early systolic click and an aortic ejection murmur radiating to both the carotids could be auscultated at the aortic area and at the apex. Respiratory system, central nervous system and per abdomen examination were normal. Hematological investigations revealed a normocytic, normochromic anemia (Hb 8.5 g%), a total leukocyte count of 12 000/ mm³, a normal platelet count (200×109/L) and an ESR of 65 mm at the end of one hour. The patient’s serum was positive for rheumatoid factor but other immunological manifestations such as Roth spots and Osler nodes were absent. Urinalysis was normal. A provisional diagnosis of aortic stenosis with infective endocarditis was made. Echocardiography did not reveal any vegetation. Three blood samples were collected at 4-hour intervals for bacterial culture and sensitivity on the day of admission. Empirical therapy with intravenous crystalline penicillin and gentamicin was administered pending culture and sensitivity reports. On the 3rd day of admission, a brief high-pitched diastolic murmur was heard on auscultation and repeat echocardiography revealed aortic stenosis  with regurgitation. This was associated with a fall in peripheral blood pressure (90/60 mmHg) and a positive hepatojugular reflex indicating the onset of congestive cardiac failure, for which drug therapy with digitalis was started. Blood cultures were repeated on the 7th and 14th day of admission. In the later part of the patient’s stay in hospital, serial stool cultures were also carried out.

Blood and stool samples were processed as per standard microbiological methods.² The bacterial isolate was identified with the help of biochemical reactions and antibiotic sensitivity was determined with the help of the Kirby–Bauer disk diffusion method.³ 

Salmonellae were isolated from all three blood samples collected on the day of admission. The isolate was found to be resistant to ampicillin, gentamicin, amikacin and chloramphenicol, and sensitive to ciprofloxacin and cefotaxime. After the  sensitivity report was obtained, the patient was treated with intravenous cefotaxime and ciprofloxacin. This led to an improvement in the patient’s clinical condition and follow-up blood cultures did not reveal any bacterial growth. None of the stool cultures revealed Salmonella. 

The isolate was sent for confirmation to the National Salmonella and Escherichia Centre, Research and Development Division at the Central Research Institute, Kasauli where it was identified as Salmonella enterica serotype Worthington.

Infective endocarditis commonly occurs in the setting of a prior valvular abnormality and is characterized by fever and systemic complaints such as anorexia, weakness, myalgia and arthralgia. Aerobic Gram-negative bacilli including Salmonella, Proteus, Pseudomonas and Klebsiella are rare causes of bacterial endocarditis, accounting for 1.3%–4.8% of cases.⁴

In the present case, the patient had a consistently positive blood culture, a predisposing cardiac ailment, fever, a positive test for rheumatoid factor and a raised ESR, all of which pointed towards a diagnosis of infective endocarditis. Cardiac vegetations were not detected by echocardiography. However, the sensitivity of echocardiography to the detection of cardiac vegetations has been found to be in the range of 60%–65%.⁴

Salmonellae have a predilection for involving previously diseased cardiac valves. Valvular perforation, atrial thrombi, myocarditis and pericarditis are common complications of Salmonella endocarditis and these events are associated with grave prognosis.⁴ In this case, the appearance of a new murmur and signs of congestive heart failure indicated deteriorating cardiac function.

The common serotypes of Salmonella that have been implicated as causative agents of endocarditis include choleraesuis, typhimurium and enteritidis.⁴ Amongst the infrequent Salmonella serotypes, Schneider et al.⁵ reported a case of Salmonella endocarditis due to serotype Thompson. In a study on salmonellosis in patients with neoplastic diseases, Wolfe et al.⁶ reported a case of endocarditis due to serotype Derby. In a review of endocarditis caused by nontyphoidal Salmonella,⁵ case reports implicating serotypes Fayed, Sendai, Dublin, Oranienburg, Infantis and Minnesota have been described. In this review, only 3 out of 22 cases of Salmonella endocarditis had a favorable outcome.

Endocarditis due to Salmonella is usually associated with an apparent focus in the gastrointestinal tract.⁵ However, despite serial stool cultures on selective media, we could not isolate Salmonella from any of the samples. 

Serotype Worthington is an uncommon pathogen. It has been previously incriminated as a cause of neonatal septicemia and meningitis.⁷ However, to our knowledge, this is the first report of endocarditis caused by this serotype. In the present case, the organism was found to be resistant to commonly used antibiotics such as ampicillin, gentamicin and chloramphenicol. Resistance to multiple antibiotics has been increasing in isolates of nontyphoidal Salmonella and  this is one of the important causes of the poor prognosis associated with Salmonella endocarditis.⁵ In other cases in which serotype Worthington has been isolated, the organism was found to be sensitive only to ciprofloxacin and a combination of amoxycillin–clavulanic acid.⁷ Infection of endocardium with multidrug-resistant Salmonella is associated with grave prognosis.⁴ In our patient, close monitoring and intensive therapy with cefotaxime and ciprofloxacin led to a favorable microbiological response and clinical improvement in the congestive cardiac failure. Although further monitoring for valvular dysfunction and cardiac failure was warranted, the patient was discharged after 17 days against medical advice. At discharge, she was advised to undergo consultation for prophylaxis of endocarditis before any surgical intervention. Surgical management for valvular heart disease was not planned due to economic reasons. 

Acknowledgments

We would like to acknowledge the assistance rendered by the Central Research Institute, Kasauli in identification of the Salmonella serotype and the Dean, B.J. Medical College and Sassoon Hospitals, Pune for providing the necessary facilities. 

Correspondence: 
Dr Abhijit M Bal, 
47/A, Ideal Colony, Radheya Apartments,
Flat-2, Kothrud, Pune,
Maharashtra 411038 
e-mail: balabhijit@operamail.com

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