Role of blood culture systems in the evaluation of epidemiological features of coagulase-negative staphylococcal bloodstream infection in critically ill patients.

The impact of blood culture systems on the detection of coagulase-negative staphylococcal bloodstream infections in critically ill patients prior to and following the introduction of the Bactec 9240 blood culture system (Becton Dickinson Diagnostic Instrument Systems, USA), which replaced the Bactec NR 730 (Becton Dickinson Diagnostic Instrument Systems), was investigated over a 3-year period. Following the introduction of the new culture system, the incidence of bloodstream infections doubled (P<0.001). Patient demographics, severity of illness, and mortality remained unchanged, while the annual standardized mortality ratio decreased significantly. These data suggest that blood culture systems may have a major impact on the perceived incidence of coagulase-negative staphylococcal bloodstream infections in this population.

[Gentamycin distribution volume in a mechanically ventilated patient-- pharmacokinetic and clinical aspects].

Mechanical ventilation (MV) of more than 32 hours may alter the gentamycin pharmacokinetic profile by increasing its volume of distribution (VD). As a result, the standard garamycin dosage regime has to be adjusted in order to obtain an adequate peak serum concentration, which is well correlated with the efficacy of garamycin therapy. Garamycin is a water-soluble drug with negligible binding to plasma albumin, so its VD approximates the volume of extra-cellular fluid, which may be expanded by MV. MV-related fluid retention is mediated via various homeostatic compensatory systems. They are activated to combat the decrease in cardiac output and central blood volume caused by MV, due to the increase in airway and intrathoracic pressure. These phenomena are more prominent during prolonged ventilation, PEEP or C-PAP ventilation, and in previously hypovolemic patients. Patients requiring MV for more than 32 hours had an average garamycin VD of 0.36 L/Kg compared with the mean VD of 0.25 L/Kg in normal adults. In the patient presented, a similar change in garamycin VD was seen, while conventional doses given during MV failed to reach suitable clinical peak levels.

[Incidence, antimicrobial resistance and mortality in bloodstream infections in the critically ill].

Bloodstream infections (BSI) are 7-fold more common in patients admitted to the intensive care unit (ICU) rather than to other hospital wards. The epidemiology of BSI in critically ill patients in Israel has not been systematically addressed. We examined the annual trends in BSI in patients in a general ICU of evolving patterns of antimicrobial resistance and associated mortality rates for the years 1994-1996. The presence of the systemic inflammatory response syndrome (SIRS) when the first positive blood cultures are taken was a prerequisite for its definition as clinically significant. The unit site, staff, practice guidelines, and type of patient were unchanged during the study period. Blood cultures were positive in 220.7-332.0 patients per 1000 ICU admissions, 18-22-fold more common than in regular ward patients. SIRS was a universal finding in these ICU patients. There was multi-drug resistance for the majority of species cultured, reaching 100% in some cases. Crude hospital mortality of ICU patients, with and without positive blood cultures, was 31-54% and 5-14%, respectively. The introduction of a new blood culture system (Bactec 9240) in 1996 was associated with a 61% increase in the rate of patients with positive blood cultures, accounted for mostly by increased isolation of coagulase-negative staphylococci. However the mortality rate for the latter decreased by 59%, suggesting the possibility of a selective increase in detection of contaminated cultures. Although highly prevalent in the study population and generally defining a patient group with high mortality risk, the specificity of SIRS-associated positive blood cultures may be species and culture-system dependent. These findings re-emphasize the need for both improved control measures for the epidemic proportions of BSI and multi-drug antimicrobial resistance, as well as more specific indicators of the clinical relevance of positive blood cultures in critically ill patients.

Plasmapheresis in neuroleptic malignant syndrome.

Neuroleptic malignant syndrome is a severe and potentially fatal reaction to neuroleptic drugs. Treatment requires withdrawal of the neuroleptic agent, metabolic and cardiovascular support, physical cooling and treatment with dantrolene sodium and bromcriptine mesylate. We report a therapeutic success of plasmapheresis in a case of neuroleptic malignant syndrome in which conventional therapy had failed. We postulate that plasmapheresis may prove to be a useful tool in treating this frequently fatal disease.