Comparison of the performance of three variations of the Carbapenem Inactivation Method (CIM, modified CIM [mCIM] and in-house method (iCIM)) for the detection of carbapenemase-producing Enterobacterales and non-fermenters.

OBJECTIVE: The objective of this study was to compare the performance of an in-house CIM (iCIM) modification with the CIM and mCIM for the detection of carbapenemase production in 149 well characterised isolates (70 carbapenemase producers and 79 non-carbapenemase producers). METHODS: Isolates were tested using the CIM, mCIM and iCIM procedures. The gold standard was genotypic characterisation by PCR. RESULTS: For Acinetobacter baumannii, the sensitivity was low (10%) for the mCIM, 70% for the CIM but was 100% for the iCIM, with a specificity of 100% for all three. For Enterobacterales, the sensitivity of all three tests was 100% for Ambler class A and B ß-lactamases, while the iCIM also had a sensitivity of 100% for class D ß lactamases. The sensitivity in Enterobacterales was highest for the iCIM at 100% (CIM 98.2%, mCIM 96.2%). The specificity was 100% for the mCIM and 98% for the CIM and iCIM. For Pseudomonas aeruginosa, the sensitivity of the CIM (100%) was higher than the iCIM (85.7%) and the mCIM (71.4%). iCIM exhibited excellent sensitivity (100%) and specificity (98%) for carbapenemase detection in Enterobacterales and was able to detect two OXA-232 producers that the mCIM did not detect and an OXA-181 producer that the CIM did not detect. CONCLUSIONS: In conclusion, iCIM performed better than the CIM and mCIM for carbapenemase detection in A. baumannii and Enterobacterales, however the CIM achieved the highest sensitivity for carbapenemase detection in P. aeruginosa suggesting that different CIM variations should be utilised depending on the organism type.

Effect of TNP on the microbiology of venous leg ulcers: a pilot study.

OBJECTIVE: To investigate the effect of topical negative pressure, delivered using Vacuum Assisted Closure (VAC, KCI), on the microbiology of chronic, non-infected venous leg ulcers (VLUs). METHOD: Patients receiving compression therapy for a chronic VLU were recruited into this prospective pilot study. The ulcer was swabbed and VAC was applied at 125mmHg continuous sub-atmospheric pressure on day 1 for six days. Standard methods for bacteriological sampling and measuring the wound surface area were applied at baseline and at the VAC dressing changes on days 3 and 6. Log median colony forming units (CFUs) per cm2 were used for statistical analyses. The bacterial species were identified. RESULTS: Seven patients were recruited into and completed the study. The median log10 CFU/cm2 on days 1, 3 and 6 were 3.5, 4.7 and 5.1 respectively. There was a significant increase in bacterial colonisation between days 1 and 6 (p<0.02). No change was observed in the identified microbiological species during therapy with VAC. CONCLUSION: This pilot study suggests that VAC therapy increases absolute numbers of bacteria colonising non-infected leg ulcers. DECLARATION OF INTEREST: KCI supplied the VAC equipment and ARANZ the SilhouetteMobile, but both had no other influence on the study.

Antibiotic susceptibility of Streptococcus pneumoniae in New Zealand.

AIMS: To determine the current antibiotic susceptibility patterns of Streptococcus pneumoniae from four centres in New Zealand. METHODS: Over a six-month period in 1997, 386 consecutive clinical isolates of S pneumoniae were collected by four laboratories (Auckland, Wellington, Hamilton and Christchurch) from general practice or inpatients. Susceptibility testing for seven antibiotics was performed by each centre using the Etest. RESULTS: Eighty-three-percent of isolates were penicillin susceptible, 12% showed intermediate resistance to penicillin and 5% were penicillin resistant. Overall, 93 and 91% of isolates were susceptible to amoxicillin/clavulanic acid and ceftriaxone, respectively. Erythromycin and tetracycline had similar rates of susceptibility (88 and 87%, respectively). Resistance to cotrimoxazole was common, with only 57% of isolates susceptible to this combination. No National Committee for Clinical Laboratory Standard (NCCLS) breakpoints were available for cefaclor to allow interpretation of the minimum inhibitory concentration data for this agent. Wellington had lower resistance rates than Auckland, Christchurch and Hamilton. Isolates from children had consistently higher resistance rates (two- to five-fold greater for beta-lactams and 1.2 to 1.3-fold for other agents) compared with isolates from adult patients. CONCLUSIONS: Resistance to multiple antibiotics among S pneumoniae is now evident in New Zealand, although rates varied between study centres. The overall rate of penicillin resistance is 5%, which is similar to that observed in many European and US cities but lower than the rates reported in badly affected areas (> 30%). These data suggest that amoxicillin (+/- clavulanic acid), erythromycin or tetracycline are appropriate agents for empirical use in less serious community acquired infections when S pneumoniae is suspected. Ceftriaxone, with or without vancomycin, should be considered in the empirical treatment of invasive, disease until sensitivities are known.

Invasive aspergillosis in severely neutropenic patients over 18 years: impact of intranasal amphotericin B and HEPA filtration.

The impact of intranasal amphotericin B and high-efficiency particulate air (HEPA) filtration on the incidence of invasive aspergillosis was reviewed in patients from 1977 to 1994 undergoing intensive chemotherapy. Overall, the incidence of proven invasive aspergillosis was reduced from 24.4% (1977-1984) to 7.1% (1985-1991) (P < 0.001) following the introduction of intranasal prophylaxis, but when probable cases of aspergillosis were included and lymphoma cases excluded, there was no change in incidence. Following the introduction of HEPA filtration, patient exposure to aspergillus spores as measured by air sampling was markedly reduced and there were no new cases of invasive aspergillosis. HEPA filtration proved effective in reducing invasive aspergillosis and has allowed increasingly aggressive treatment regimens to be introduced.

A case control study to determine risk factors for campylobacter infection in Christchurch in the summer of 1992-3.

AIM: This study was designed to determine the risk factors for acquiring campylobacter infection in Christchurch in the summer of 1992/3. METHODS: A case control study was conducted of 100 cases and controls from urban areas matched for age and sex. Cases and controls were interviewed by telephone using a questionnaire and results analysed using the Epi Info statistical computer programme. RESULTS: Eighty one percent of both cases and controls had recently consumed poultry. Eating poultry at a friends house (OR = 3.18, CI 1.0, 10.73, p = 0.03), at a barbecue (OR = 3.00, CI 0.99, 9.34, p = 0.03) or eating undercooked chicken (OR = 4.94, CI 1.03, 23.62, p = 0.05) was a risk whereas eating at home was protective (OR = 0.36, CI 0.14, 0.9, p = 0.02). Other factors associated with increased risk were drinking water from a nonurban supply (OR = 2.7, CI 0.89, 8.33, p = 0.09) or consumption of chicken bought fresh (OR = 1.8, CI 0.85, 3.82, p = 0.10). CONCLUSION: Poorly cooked or handled chicken is a significant source of human campylobacter infection. Morbidity may be reduced by increased public awareness and improvement of cooking practices.

A prospective study of isolation of Moraxella catarrhalis in a hospital during the winter months.

Sputum samples submitted to the microbiology laboratory from general medical and respiratory wards were monitored for Moraxella catarrhalis on a prospective basis. All isolates were typed by restriction endonuclease typing. Nosocomial spread was found both by the clustering of cases and typing of isolates. Sampling of the environment of some cases was performed. Seven out of 37 samples revealed environmental contamination. Sampling for persistence of the organism in the environment was positive on one occasion out of 13. Evaluation of acquisition of M. catarrhalis in relation to length of stay showed that the average length of stay of a case with M. catarrhalis was considerably longer than average patient stay without M. catarrhalis. Four patients had two isolates available for typing. The type of M. catarrhalis was different on the second occasion to that on the first. Nosocomial spread of M. catarrhalis in the setting of general medical and respiratory wards was found to occur in the winter months.

Intranasal amphotericin B reduces the frequency of invasive aspergillosis in neutropenic patients.

PURPOSE: To retrospectively study the prophylaxis of invasive aspergillosis in neutropenic patients and to relate the frequency of this fungal disease to any causal or modifying factors that could be identified. PATIENTS AND METHODS: Between 1977 and 1988, 130 patients underwent 158 intensive treatment episodes to control acute leukemia, lymphoma, and aplastic anemia, and the frequency of complicating aspergillus infection was determined. RESULTS: Proven invasive aspergillus infections occurred in 22 cases, 12 of which were fatal. Invasive aspergillosis was suspected in a further 16 cases and all these patients recovered with amphotericin B treatment. Colonization by Aspergillus in the absence of clinically significant infection was seen in 31 treatment episodes. Invasive aspergillosis involved mainly the upper and lower respiratory tract and skin. Control of the infection was closely related to the control of the underlying disease, with subsequent return of normal marrow function and resolution of neutropenia. The incidence of aspergillus infection has decreased dramatically since 1985, most probably due to the introduction of intranasal amphotericin B. This occurred despite the persistence of aspergillus spores in the hematology ward air during the 1986 to 1988 period. CONCLUSION: Intranasal aerosolized amphotericin B may protect against invasive aspergillosis, even when neutropenic patients are cared for in conventional wards without HEPA filtration.

Epstein-Barr virus infection acquired from a cadaveric renal transplant.

A 42-year-old man, seronegative for Epstein-Barr virus (EBV), received a cadaveric renal transplant. Serology from the 27-year-old male donor indicated an active EBV infection. Following treatment for acute rejection with OKT3 the recipient developed a severe systemic illness. Clinical features strongly suggested an acute EBV infection and serology showed seroconversion for EBV. The patient died and autopsy histology revealed widespread polymorphic lymphocyte infiltration in lymph nodes and solid organs. To our knowledge this is the first report of a kidney being transplanted from a donor who was subsequently shown to have had EBV infection at the time of organ retrieval. The EBV status of an organ donor should be considered more frequently.

Malaria in Christchurch.

Thirty seven cases of malaria were diagnosed in the Christchurch Hospital Microbiology Laboratory from January 1978 to December 1983. Cases occurred in most age groups with various occupations. Prophylactic drugs may not give protection because of lack of patient compliance and/or parasite resistance. A case of malaria which recrudesced following treatment recommended in New Zealand is also included.

Campylobacter jejuni myocarditis.

A case of Campylobacter jejuni (C. jejuni) myocarditis in a young man is described. C. jejuni was isolated from the patient's stools and he developed specific antibodies to this organism. Tests for other etiological agents (Salmonella, Shigella, Brucella abortus, beta-hemolytic streptococcus Group A, Treponema pallidum and coxsackievirus B) proved negative.