Israel Medical Association Journal

Background: Skin colonization of microorganisms in blood cultures (BCs) are generally considered clinically non-significant and can be the source of a true infection, particularly in immunosuppressed patients.

Objectives: To study the epidemiology and risk factors for bacteremia caused by contaminants.

Methods: This retrospective, descriptive study is based on adult BCs collected (2004–2013) and categorized as positive (True bacteremia [TrueB] or contamination) or negative. Clinical, demographic, and laboratory characteristics of BCs positive for the six most common potential contaminant pathogens (PCPs) that can cause TrueB and contamination (Coagulase-negative Staphylococcus [CoNS], Streptococcus viridans, Propionibacterium acnes, Corynebacterium spp., Bacillus spp., Clostridium spp.) were assessed. Ninety-two TrueB were identified vs. 196 contaminations (1:2 ratio).

Results: From 74,014 BCs, PCPs were found in 3735 samples, of which 3643 (97.5%) were contaminations and 92 (2.5%) were TrueB. The overall rate of BC contamination decreased during the study period from 6.7% to 3.8%. CoNS was the most common PCP. Bacillus spp. were only contaminants. Clostridium spp. and Streptococcus viridans were more often TrueB. In a multivariate model, predictors of TrueB included high creatinine levels, Streptococcus viridans in BC, and multiple positive BCs. A single culture of CoNS was strongly predictive of contamination.

Conclusions: Ten years of data on BCs, focusing on six PCPs, demonstrates a significant, yet insufficient reduction in the rate of contamination. High creatinine level, isolation of Streptococcus viridans, and multiple positive BCs were predictors of TrueB, while growth of CoNS was strongly predictive of contamination. This model could assist in diagnostic and therapeutic decision making.

Background: The compliance of hospital staff with guidelines for the active surveillance of methicillin-resistant Staphylococcus aureus (MRSA) in Israel has not been determined.

Objectives: To evaluate the compliance of hospital staff with guidelines for the active surveillance of MRSA and assess its impact on the incidence of nosocomial MRSA bacteremia.

Methods: We assessed compliance with MRSA surveillance guidelines by assessing adherence to the screening protocol and reviewing medical and nursing charts of patients colonized with MRSA, and observed hand hygiene opportunities among health care workers and colonized patients. Rates of nosocomial MRSA bacteremia and of adherence with hand hygiene among overall hospital staff were obtained from archived data for the period 2001–2010.

Results: Only 32.4% of eligible patients were screened for MRSA carriage on admission, and 69.9% of MRSA carriers did not receive any eradication treatment. The mean rate of adherence to glove use among nurses and doctors was 69% and 31% respectively (P < 0.01) and to hand hygiene 59% and 41% respectively (P < 0.01). The hospital overall rate of adherence to hand hygiene increased from 42.3% in 2005 to 68.1% in 2010. Rates of nosocomial MRSA bacteremia decreased by 79.2%, from 0.48 (in 2001) to 0.1 (in 2010) per 1000 admissions (P < 0.001).

Conclusions: The compliance of medical and nursing staff with guidelines for active MRSA surveillance was poor. The encouraging increase in adherence to hand hygiene and concomitant decrease in nosocomial MRSA bacteremia is gratifying. The deficiencies in compliance with MRSA infection control policy warrant an adjusted strategy based on the hospital resources.

Background: Many beside urine culture devices have been developed with the aim of reliability, simplicity and use in both the physician’s office and the clinical laboratory. 

Objective: To compare a novel beside urine culture device (DipStreak, Novamed Ltd. Israel) comprising a combination of MacConkey and Colombia CAN blood agar with conventional seeding on the same culture media. 

Methods: A total of 1000 urine specimens sent to our microbiology laboratory were simultaneously processed by both methods. Results were evaluated after 24 and 48 hours incubation at 370C. 

Results: Altogether, 171 (17.1%) and 124 (12.4%) specimens were defined as positive by the conventional method using cutoff values of 104 colony-forming units/ml and 105 CFU/ml respectively; 178 specimens (17.8%) were defined as contaminated. The sensitivity, specificity, positive and negative predictive values of DipStreak for urinary tract infection were 98.8%, 98.6%, 96% and 99.6% respectively, using a cutoff value of 104 CFU/ml, and 99.3%, 99.2%, 96% and 99.8 respectively, using cutoff value of 105 CFU/ml. Full agreement between both techniques was 95%. 

Conclusion: The agreement rate between DipStreak and conventional seeding was remarkably high. These results suggest that DipStreak in the agar combination tested in this study is a useful and precise tool for diagnosing urinary tract infection.