Knud Siboni

Infections following epidural catheterization

Seventy-eight patients with culture-positive epidural catheters, were studied. Fifty-nine had symptoms of exit site infection and 11 patients had clinical meningitis, two of whom also had an epidural abscess. This corresponds to a local infection incidence of at least 4.3% and an incidence of central nervous system infection of at least 0.7% at Odense University Hospital. This degree of infection is of the same magnitude as that reported for intravascular devices. We found that the patients with generalized symptoms of infection had been catheterized for a longer time, and were older than patients with only local symptoms of infection. The microorganisms isolated from the tips of the epidural catheters were coagulase-negative staphylococci (41%), Staphylococcus aureus (35%), Gram-negative bacilli (14%) and others (10%). The Gram-negative bacilli and S. aureus caused serious infections more frequently than the others. We discuss the symptoms and diagnosis of spinal epidural abscess and suggest a proposal for prophylactic and diagnostic guidelines for epidural catheter-related infections.

Epidemic spread of Acinetobacter calcoaceticus in a neurosurgical department analyzed by electronic data processing

An epidemic spread of Acinetobacter calcoaceticus var. anitratus in two neurosurgical wards is described retrospectively and prospectively using electronic data processing. Isolation of the species from sputum preceded the isolation from CSF by 1/2-1 year. Control measures directed against spread by air and indirect contact controlled the epidemic. Reexamination of 20 selected strains from the epidemic revealed two distinct resistance patterns.

Nosocomial respiratory syncytial virus infections in a paediatric department

The seasonal problem of respiratory infections in children caused by respiratory syncytial virus (RSV) is worldwide. A number of these infections are known to occur by nosocomial acquisition. In order to reduce the risk, measures, such as cohort nursing and handwashing, have been used in the paediatric department of Odense University Hospital for three years. In a retrospective evaluation of this routine practice the incidence of nosocomial RSV infections was recorded. The overall rate of nosocomial infection was low, but was proportionally highest in the unit for children aged under 6 months; no change in incidence was seen over the three-year period. In the infectious disease unit, where the majority of RSV infected children were admitted, the rate of nosocomial infection decreased despite an unchanged routine. This difference cannot be explained simply on the basis of longer hospital admission of the children under 6 months of age, but might relate to acquired immunity in children of all ages in the infectious diseases unit or better facilities for segregation within that unit.

Resistance problems in two university hospitals in Denmark

In 1997, 80 and 89% of Staphylococcus aureus isolated from university hospitals in Odense and Hvidovre respectively were resistant to penicillin and 32.0 and 41% of Escherichia coli were resistant to ampicillin. There were low incidences of methicillin resistance in S. aureus (<1%), penicillin resistance in Streptococcus pneumoniae (3%),and gentamicin in E. coli (2%). These figures might reflect the low use of antibiotics in Denmark.

Studies on clinical isolates of coagulase‐negative staphylococci resistant to methicillin

The in vitro susceptibility to cephalothin and cefuroxime of 195 isolates of methicillin‐resistant coagulase‐negative staphylococci was determined by the agar‐diffusion test, using 7.5% NaCl‐supplemented agar. The distribution of the inhibition zone diameters for isolates of S. epidermidis (S. biotype 1) as well as for S. haemolyticus (S. biotype 4) was trimodal. While 4% of the isolates were found susceptible to cefuroxime, 39% of the S. epidermidis/S. hominis (S. biotype 1) isolates and 34% of the S. haemolyticus (S. biotype 4) isolates were found susceptible to cephalothin by this method. Eight of these isolates (six S. epidermidis, two S. haemolyticus) were selected for susceptibility testing by the tube‐dilution method, together with four isolates (three S. haemolyticus, one S. epidermidis) found resistant to cephalothin by the agar‐diffusion test. The first‐mentioned isolates were all found susceptible to cephalothin with MICs ≤ 2 μg/1, while the last‐named all were resistant with MICs ≥ 16 μg/ml. Population analyses revealed sub‐populations of highly resistant bacteria in all methicillin‐resistant isolates of S. epidermidis (S. biotype 1), as well as in all isolates of S. haemolyticus (S. biotype 4). We thus concluded that methicillin‐resistance in isolates of coagulase‐negative staphylococci implies resistance to cephalosporins and that the difference between S. epidermidis and S. haemolyticus as regards cephalosporin‐susceptibility is quantitative and not qualitative. Eighty‐nine per cent of the 195 methicillin‐resistant isolates in this study were resistant to penicillin and at least one more antibiotic. We therefore think that resistance to penicillin and one or more non‐beta‐lactam antibiotics strongly suggests methicillin‐resistance and that such isolates should be further tested on hypertonic media.

Studies on ampicillin resistance in Achromobacter xylosoxidans

Population analyses of susceptibility to ampicillin in ampicillin‐susceptible and ampicillin‐resistant strains of Achromobacter xylosoxidans revealed the existence of ampicillin‐resistant subpopulations in ampicillin‐susceptible isolates. Bacteria resistant to a concentration four times the one that inhibited the majority population had a frequency of 10‐3 to 10‐4. Strains isolated from aqueous environments are often found susceptible to ampicillin, while sporadic cases of infections with A. xylosoxidans are often caused by ampicillin‐resistant strains. We suggest that the isolation from clinical specimens of ampicillin‐susceptible strains, therefore, may be an indication of nosocomial infections due to recently contaminated aqueous solutions or medical equipment.