D. Surveillance.Sensitivity_testing.html. C.Registration

Epidemiological surveillance depends on:

  1. Clinical observation in the wards and
  2. Recording in the Department of Clinical Microbiology of microorganisms isolated from patients with infections or from carriers, characterized as species or subspecies. See also: The_role_of_the_CM_laboratory_in_infection_control.

Is the species uncommon for the category of specimen, p < 0.01, this marker is sufficient for the recognition of cumulations. Examples are: Achromobacter xylosoxidans, Burkholderia cepacia, Chryseobacterium meningosepticum or Ps. fluorescens from blood, Enterobacter sakazakii from spinal fluid, and Str. pyogenes from surgical wounds. Two cases with these species within four weeks constitute an epidemic, p = 1 x <0.01 = < 0.01.

With the last named, grouping and typing will be necessary in order to render probable or to reject an epidemiological connection. And the species frequently isolated from the specimen in question will need a sero-fermentative phage and resistance(R) type and perhaps a ribotype. Characterization may be stopped as soon as coincidence by chance is sufficiently improbable.

Next to speciation, resistance typing is important, performed as it is on all isolates of clinical relevance. Recorded into an electronic data processing system, the complex species+R-type is a useful variable.AIM.html

Resistance traits

May depend on mutation or on transmission of genes, transduced within the same species and transmitted between species on a plasmid or by a transposon. See also D.Evaluation.

Selection.

Dominance of an R-type depends on selection due to one or more of the antibiotics included in the R-type. This epidemiological work rests, therefore, also on information of the usage of antibiotics in the different clinical departments or wards.

The councelling of the clinical microbiologist concerning the patients is an important link in the surveillance and selection may be minimized through the restrictive antibiotics' policy chosen.

Imported multiresistant strains.

Selection may happen abroad with antibiotics usually not used in Denmark: amikacin and vancomycin, or in amounts usually avoided of newer cephalosporines and carbapenems. Such strains usually also carry R-traits to the antibiotics routinely used in Denmark and are consequently selected by these. Patients and hospital personnel coming to Denmark from non-scandinavian hospitals are, therefore, isolated and screened for methicillin-R Staphylococcus aureus, vancomycin-R Enterococcus fæcium, and Enterobacteriaceæ carrying B-lactamases with extended spectrum (ESBL) (L 24).