Length of exposure to the hospital environment is more important than antibiotic exposure in healthcare associated infections by methicillin-resistant Staphylococcus aureus: a comparative study

OBJECTIVES: Both total antimicrobial use and specific antimicrobials have been implicated as risk factors for healthcare-associated methicillin-resistant Staphylococcus aureus (HCA-MRSA) infection. The aims of this study were: (I) to explore predictors of a new HCA-MRSA infection in comparison with a new healthcare-associated methicillin-sensitive Staphylococcus aureus (HCA-MSSA); (II) to thoroughly assess the role of recent antibiotic use qualitatively and quantitatively. METHODS: The time-period for our study was from October 1997 through September 2001. Through applying strict criteria, we identified two groups of inpatients, one with a new HCA-MRSA infection and one with a new HCA-MSSA infection. We recorded demographic, clinical and antibiotic use-related data up to 30 days before the positive culture date. RESULTS: We identified 127 and 70 patients for each group, respectively. Two logistic regression models were carried out to assess the role of antimicrobial use (qualitatively and quantitatively). In model I, duration of hospital stay, presence of chronic wounds, aminoglycoside and fluoroquinolone use retained statistical significance. In model II, duration of hospital stay and history of intubation during the last month stood out as the only significant predictors of a subsequent HCA-MRSA infection. No significant differences in outcome were noted. CONCLUSIONS: The length of exposure to the hospital environment may be the best predictor of a new HCA-MRSA infection. Use of aminoglycosides and fluoroquinolones may also stand independently along with presence of chronic ulcers and surgical procedures. No independent association between quantitative antibiotic use and subsequent HCA-MRSA infection was documented.

Fulminant pancytopenia due to cytomegalovirus infection in an immunocompetent adult

A case of severe and irreversible pancytopenia secondary to acute primary cytomegalovirus infection in an immunocompetent woman is described. The patient presented with thrombocytopenia, lymphopenia, anemia, and abnormal liver function tests. Treatment with corticosteroids and intravenous immunoglobulin was ineffective in reconstituting hemopoiesis. The patient developed severe sepsis and eventually expired.

Primary sternal osteomyelitis caused by Nocardia nova: case report and literature review

A 51 year old woman without significant past medical history or risk factors for Nocardia infection developed primary Nocardia nova sternal osteomyelitis with mediastinal abscess, diagnosed with open biopsy. She required prolonged antibiotic therapy and had a favorable outcome. Primary sternal osteomyelitis develops in the absence of a contiguous focus of infection, as opposed to secondary sternal osteomyelitis, which is usually a complication of sternotomy. Staphylococcus aureus probably still is the most common cause of both forms of sternal osteomyelitis. Nocardia species invade humans usually through the respiratory tract and can cause a variety of localized infections through the hematogenous route. Pulmonary involvement may or may not coexist. Immunosuppressed patients are more prone to infection by Nocardia species, although cases involving seemingly immunocompetent patients are not rare. This is the first reported case in the English literature of primary sternal osteomyelitis due to Nocardia nova or any other Nocardia species.