Streptobacillus moniliformis septic arthritis: a clinical entity distinct from rat-bite fever?

BACKGROUND: Streptobacillus moniliformis is a zoonotic agent associated with rodent contacts. Although it is more commonly reported to cause rat-bite fever with reactive arthritides, it can also lead to pyogenic infection of the joints. CASE PRESENTATION: We present a lady with past history of osteoarthritis developing streptobacillary septic arthritides of the right knee and left wrist, and required antibiotic and arthrotomy for treatment. We also review 11 previously reported cases of streptobacillary septic arthritis to discuss the characteristics, treatment, prognosis of the infection, and illustrates the differences between streptobacillary rat-bite fever and septic arthritis. Among this patient population, most patients had potential contact with rats (91.6%). The knee is the most commonly affected joint (58.3%), and 83.3% patients having polyarticular involvement. As opposed to rat-bite fever, fever and rash was only present in 58.3% and 16.7% of patients respectively. S. moniliformis bacteremia is uncommon (8.4%) and the prognosis is good. CONCLUSION: Arthrocentesis is useful in distinguishing streptobacillary septic arthritis from reactive arthritis of rat-bite fever. The sole use of commercial media containing sodium polyanethol sulfonate may render the bacterial culture negative. A detailed history of possible exposure to rodents should be elicited from patients with arthritis in order to facilitate microbiologic diagnosis.

Epidemiology and genetic diversity of methicillin-resistant Staphylococcus aureus strains in residential care homes for elderly persons in Hong Kong.

OBJECTIVE: To determine the prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) strains among residents in residential care homes for the elderly in Hong Kong. DESIGN: Cross-sectional and descriptive study. PARTICIPANTS: A total of 949 residents in 13 residential care homes for elderly persons in Hong Kong in January 2005. METHODS: MRSA colonization was assessed by culture of swab specimens from anterior nares and active skin lesions. Characteristics of residents were obtained by a standard questionnaire. All MRSA isolates were analyzed by polymerase chain reaction for their staphylococcal cassette chromosome (SCC) mec content and were typed by pulsed-field gel electrophoresis (PFGE) and multilocus sequencing. RESULTS: MRSA colonization was detected in 27 residents (2.8%). No MRSA was found in 2 facilities. The rate of MRSA carriage in the other 11 facilities ranged from 1.9% to 4.2%. In univariate analysis, functional immobility (odds ratio [OR], 1.4), history of hospital admission (OR, 2.3), and the use of nebulized medication (OR, 5.4) were significantly associated with MRSA colonization. The isolates had 11 unique antibiograms, with 14 isolates susceptible to all but 1 or 2 of the non- beta -lactam antimicrobial agents tested. The isolates exhibited SCCmec types I (1 isolate), II (2 isolates), III (1 isolate), IV/IVA (10 isolates), and V (13 isolates). No isolates had the Panton-Valentine leukocidin genes. PFGE analysis clustered all except 1 isolate into 7 PFGE types, designated HKU10 to HKU70. Between 1 and 4 unique PFGE types were found in the individual residential care facilities. CONCLUSION: This study documented the emergence of SCCmec types IV and V among genetically diverse MRSA strains in residential care homes for elderly persons in Hong Kong.

Mycobacterium tuberculosis sternal wound infection after open heart surgery: a case report and review of the literature.

Tuberculous osteomyelitis of sternum after open heart surgery is a rare disease entity. We report a case of wound infection with osteomyelitis caused by Mycobacterium tuberculosis in a patient with diabetic nephropathy, requiring peritoneal dialysis after coronary artery bypass grafting, who was successfully treated with antituberculous agents and surgical debridement. In addition, we provide a literature review on reported cases of tuberculous sternal osteomyelitis and mediastinitis after open heart surgery, and discuss about the risk factors, clinical features, and treatment of this infection.

Misidentification of a mucoid strain of Salmonella enterica serotype choleraesuis as Hafnia alvei by the Vitek GNI+ card system.

Nontyphoidal salmonellae are among the most common causes of bacterial gastroenteritis worldwide. They are also notable causes of extraintestinal infections, including bacteremia and vascular infections. Salmonella enterica serotype Choleraesuis is typically associated with invasive infections. We report a patient who had an infected intra-abdominal aortic aneurysm due to an unusually mucoid strain of Salmonella enterica serotype Choleraesuis. The isolate was erroneously identified as Hafnia alvei by the Vitek GNI+ card system. A blood culture isolate taken from the same patient 9 months earlier was also identified as H. alvei by the Vitek GNI+ card system. Despite an apparent cure with intravenous amoxicillin-clavulanic acid at that time, the Salmonella infection had not been cleared and manifested as a ruptured infected abdominal aortic aneurysm. Repeated passage of the strain yielded nonmucoid colonies, which were correctly identified by the API and PHOENIX systems. The isolates from the aneurysm and the former bacteremic episode were found to be identical using pulsed field gel electrophoresis. The fallibility of automated bacterial identification systems is highlighted. Such errors are especially important for isolates in which in vitro antibiotic susceptibility testing does not correlate with the clinical success of treatment, as illustrated by Salmonella infections.

Recurrent bacteraemia caused by different Salmonella species in a systemic lupus erythematosus patient.

Non-typhoidal Salmonella infections are increasingly being encountered. Recurrent systemic salmonellosis has previously been reported in both immunocompromised and immunocompetent hosts. However, recurrent salmonella bacteraemia by different species of salmonella has rarely been described. We report a patient with systemic lupus erythematosus having Salmonella enteritidis and Salmonella typhimurium infections after ingesting raw eggs and vegetables. Multiple internal organs, including left knee joint, left ovary and bones, were involved. The patient recovered with a prolonged course of antibiotics. This case illustrates that recurrent systemic salmonellosis can be caused by different species of pathogens, especially in immunocompromised hosts. Detailed food history and education on food hygiene is essential in making the diagnosis and preventing recurrence. A prolonged course of antibiotics may be needed to manage these cases.