Endemic nosocomial gram-negative bacteraemias resulting from contamination of intravenous heparin infusions

A cluster of Klebsiella pneumoniae bacteremia in a radiation oncology ward

BACKGROUND

We report an outbreak of genetically related strains of Klebsiella pneumoniae bloodstream infection.

METHODS

The practices that were possibly related to the outbreak were investigated through direct observation and interviews with staff by infection control team. Cultures of potential environmental sources of bacteria were obtained.

RESULTS

Six patients receiving intravenous medications in saline solution developed fever and shaking chills 1.5 to 4 hours after the infusion was initiated. Cultures of the blood from 4 patients yielded K. pneumoniae. Molecular characterization of K. pneumoniae done by pulsed-field gel electrophoresis revealed the same strain.

CONCLUSION

Although a definite source for the outbreak could not be identified, probably environmental contamination, lack of adherence to hand hygiene practices, contamination, and cross contamination led to this outbreak.

Experimental confirmation of Serratia marcescens contamination in multiple-dose vials of heparin-saline solution

The initial contamination of heparin-saline solution (HS) in multiple-dose vials (MDVs) by Serratia marcescens was experimentally investigated using various isolates. Isolates I2 and S1 were from blood specimens from patients with a hospital-acquired infection (HAI). Isolates I13 and FHSM9043 were from urine and blood specimens, respectively, from patients without HAI. Isolate I124, with a pulsed-field get electrophoresis pattern identical to that of isolate I2, was from the hospital environment. Viable cells of isolate I2 were carried over into the HS of MDVs when the contaminated rubber septum was pierced with a syringe needle. When the outside surface of the septum was contaminated by inoculating it with wet-cell suspensions in HS or Müller-Hinton broth, the viable cells carried over were detected at a minimum inoculum size (MIS) of 10(3) s cfu/ml. However, when the surface was contaminated by inoculating it with dry-cell suspensions, the viable cells carried over were detected at an MIS of 10(7) s cfu/ml. The viable cells in the internal lumen of the needle much more than those on its outside surface spread to the HS of MDVs. For exposures of 24 h and 72 h at 4 degrees C to HS with 1% benzyl alcohol as a preservative in MDVs, viable cells of all isolates tested were detected at MIS values of 1 s and 10 s cfu/ml, respectively, increases three orders of magnitude smaller than those of reference strain IFO3736. These results suggest that S. marcescens isolates are readily carried over into the HS of MDVs by piercing a wet, contaminated rubber septum with a syringe needle. Also, despite the sterilization action of 1% benzyl alcohol, the organism persistently survived at 4 degrees C, even when initial contamination was with a small amount of inoculum.

Unexpected hospital-acquired bacteraemia in patients at low risk of bloodstream infection: the role of a heparin drip

Following a cluster of cases of unexpected hospital-acquired bacteraemia suspected to be related to an intravenous (iv) heparin drip, all cases of hospital-acquired primary bloodstream infection (BSI) in patients at low risk of bacteraemia were analysed over a four-year period. Ninety-six bacteraemic patients (6%) from 1618 episodes of hospital-acquired bacteraemia had a peripheral iv line as the only risk factor. These patients were divided into two groups: 60 patients with phlebitis and 36 without local signs of inflammation. Baseline features of the two groups were comparable, but in univariate and multivariate analysis, a significant association was found between iv heparin use, predominance of Gram-negative organisms (especially Klebsiella, Serratia and Enterobacter species), and absence of phlebitis. In spite of clear statistical association, however, the means by which the heparin solution became contaminated with Gram-negative organisms remained unknown. Following implementation of infection control methods concerning heparin handling, no more cases occurred. Unexpected hospital-acquired Gram-negative bacteraemia in patients with peripheral iv lines should prompt investigation of potential infusate-related infection, especially in patients without phlebitis and those receiving iv heparin.

Unexpected high risk of contamination with staphylococci species attributable to standard preparation of syringes for continuous intravenous drug administration in a simulation model in intensive care units

OBJECTIVE

To determine the risk of bacterial contamination of the infusate in a simulation model of syringes prepared for continuous intravenous drug administration by intensive care unit nurses. Widely accepted standard procedures in the intensive care unit were compared with syringes prepared by pharmaceutical technicians working under standard aseptic conditions according to national guidelines.

DESIGN

Prospective study.

SETTING

Intensive care units of four general teaching hospitals and two university hospitals.

SUBJECTS

We examined 650 syringes prepared from 10-mL ampules and 100 syringes prepared from rubber-compound-capped 50-mL vials by intensive care unit nurses of six hospitals. Also, 100 syringes from 10-mL ampules and 100 syringes from rubber-compound-capped 50-mL vials were prepared by pharmaceutical technicians.

INTERVENTIONS

Turbidity of syringes after culturing for 7 days at 37 degrees C was used as the criterion for possible bacterial contamination, which was proved with subsequent Gram staining.

MEASUREMENTS AND MAIN RESULTS

A median contamination rate of 22% (range, 7% to 44%) was observed for the syringes prepared from 10-mL ampules by intensive care unit nurses, compared with only 1% for the syringes prepared from ampules by technicians (p <.001). In >75% of all contaminated syringes, Gram-positive cocci were identified. At least 12% of all prepared syringes proved to be contaminated with staphylococci species. The contamination rate of syringes prepared from vials was much lower: 2% in the intensive care unit and 0% at the department of clinical pharmacy.

CONCLUSIONS

In the intensive care unit, standard procedures for preparing syringes for intravenous administration of drugs lack vigorous aseptic precautions, leading to a high contamination rate of the infusate. This risk is increased when ampules instead of 50 mL-vials are used to prepare the syringes.

Multi-centre research surveillance project to reduce infections/phlebitis associated with peripheral vascular catheters

A surveillance project was undertaken on 37 surgical wards by infection control nurses with the aim of reducing phlebitis/infections associated with peripheral vascular catheters, and to identify risk factors. Data on 2934 catheters in situ longer than 24h was collected in two separate surveillance periods and results were fed back after each surveillance period. Four significant risk factors were identified; what the catheters were used for, the duration the catheters were in situ, the surveillance period (the first surveillance period had a higher phlebitis rate than the second) and whether an infusion pump was used. Logistic regression analysis showed that each of these had a significant effect after adjusting for the effects of the other three factors.