Susceptibility patterns of bacterial isolates from intensive care and haematology/oncology patients in New Zealand.

AIMS

To determine the current susceptibility pattern of bacterial isolates from intensive care and haematology/oncology patients in New Zealand.

METHOD

Over a 6 month period 417 consecutive clinically relevant bacterial isolates from intensive care and haematology/oncology patients from seven New Zealand hospitals had their susceptibility to multiple antimicrobial agents determined by the agar plate dilution method. Methicillin resistant staphylococci were not included.

RESULTS

Of the 417 isolates, 224 (54%) were gram negative and 193 were gram positive. Predominant species/groups were: Escherichia coli 63 (15%), Enterobacter spp 26 (6%), other Enterobacteriacae 41 (10%), Pseudomonas aeruginosa 42 (10%), Staphylococcus aureus 111 (27%), coagulase negative staphylococci 30 (7%), Streptococcus spp 31 (7%), and Enterococcus spp 19 (5%). Isolate sources were: respiratory tract, 170 (41%); cutaneous sites, 81 (19%); blood, 64 (15%); and urine 63 (15%). Resistance was uncommon amongst staphylococci, streptococci, enterococci, and H influenzae. No vancomycin resistant or beta-lactamase-positive enterococci were encountered. For different groups of enteric gram negative bacilli: amoxycillin and amoxycillin-clavulanic acid resistance was common, 46-93% and 24-85% respectively; cefpirome was the most active cephalosporin; aminoglycoside resistance was uncommon; and no isolate possessed extended spectrum beta-lactamase. For P aeruginosa: most isolates were susceptible to cefpirome and ceftazidime, and aminoglycoside resistance was uncommon.

CONCLUSION

Gram positive bacteria make up a higher proportion of isolates than in a similar European study. At present New Zealand does not have widespread resistance amongst common isolates. Several agents currently available in New Zealand provide adequate cover for commonly encountered pathogens. The choice of which agent to choose therefore rests more with their purchase and administration costs, as well as safety and efficacy data than simply susceptibility data alone.