An epidemiological survey of methicillin-resistant Staphylococcus aureus in a tertiary referral hospital.

Over a 30-month period from July 1995 to December 1997, new detections of methicillin-resistant Staphylococcus aureus (MRSA) were prospectively studied in a tertiary referral hospital. The aims of the study were to determine the incidence of colonization of patients admitted to each of the hospital's 39 clinical units and ascertain where each patient had become colonized. Epidemiological information (time to detection, ward movement, admission to other hospitals, data on MRSA isolations in hospital wards) and phage typing were used by the hospital's infection control unit to make this determination. Routine containment procedures included cohorting, flagging and triclosan body washes. Surveillance cultures were collected infrequently. Patients known to be colonized with MRSA were excluded from orthopaedic and haematology wards. During the study period, 995 patients were found to be newly colonized. The incidence of colonization varied from nil to 72 per 1000 admissions, being highest in the main intensive care unit and in services which frequently used that unit. The incidence of colonization in elective orthopaedic surgery (< 1 per 1000) and haematology (3 per 1000) was very low. Determining the place where patients acquired MRSA was made difficult by the high frequency of endemic phage types and frequent patient transfer between wards. Epidemiological data suggested that the main intensive care unit and surgical wards nursing patients with colorectal, urological and vascular diseases were the places where most patients became colonized. MRSA was never acquired by patients nursed in wards which practised an exclusion policy towards patients known to be colonized with MRSA. Our data suggest that in tertiary referral hospitals, where MRSA is not only endemic but frequently imported from other hospitals, it is possible to establish areas where MRSA is never acquired.

A prospective survey of current methicillin-resistant Staphylococcus aureus control measures.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is now endemic in tertiary referral hospitals among the developed world. By prospective survey, the effect of two measures aimed to reduce the spread of MRSA was determined. First, a surgical ward with persistently high levels of MRSA detection was cleaned and renovated. Second, the medical records of all MRSA-colonized patients were electronically flagged, facilitating immediate application of control measures on readmission. METHODS: Data were collected for 995 newly colonized patients admitted between 1 July 1995 and 31 December 1997. Methicillin-resistant Staphylococcus aureus detection was determined before and after implementation of the interventions, along with the likely place of MRSA acquisition and the monthly incidence of MRSA detection for all inpatients. Chi-squared testing with odds ratios and 95% confidence intervals determined associations between the effect of control measures studied and MRSA detection rates. RESULTS: New MRSA detection was 21.6 per 1000 admissions before refurbishment compared with 20.4 per 1000 admissions to the surgical ward after refurbishment. New MRSA detection averaged 6.4 per 1000 hospital admissions before the introduction of record flagging and patient cohorting, compared with 6.2 per 1000 admissions after. CONCLUSION: Neither ward refurbishment, nor introduction of flagging, significantly reduced rates of colonization during the study period. In hospitals that receive MRSA-colonized patients and provide intensive care facilities, spread of MRSA is a major problem. Effective containment demands separate wards for MRSA-colonized and non-colonized patients. The need for such containment should be considered in design of the modern hospital.

Detection of persistent vegetative bacteria and amplified viral nucleic acid from in-use testing of gastrointestinal endoscopes.

Hospital-acquired infection attributed to inadequate decontamination of gastrointestinal endoscopes prompted an in use evaluation of recommended procedures. Specimens were obtained from the internal channels of 123 endoscopes before, during and after decontamination by flushing with saline and brushing with a sterile brush, and examined for vegetative bacteria by broth and plate culture. Four endoscopy units were tested; the chemical disinfectants used were: 2% glutaraldehyde in Centres 1 and 2 (automated) and Centre 3 (manual); peracetic acid in Centre 4 (automated). Samples from patients in Centre 1 with known chronic hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1) infection were also examined for viral nucleic acid by ultracentrifugation, nucleic acid extraction, reverse transcription (for RNA) and polymerase chain reaction (PCR). No persistent vegetative bacteria were found following standard manual cleaning and disinfection for 20 min in 2% glutaraldehyde in Centres 2 and 3 (N = 37). At Centre 1, while plate culture yielded no growth, 34% of samples (10/29) grew vegetative bacteria in broth culture after cleaning and disinfection for 20 min in 2% glutaraldehyde. Investigation revealed an error in manual cleaning; no bacteria were detected in 37 samples taken after this was corrected. At Centre 4, despite the use of peracetic acid as a sterilant, three out of 20 (15%) of post decontamination samples grew bacteria; one contained persistent bacteria. HBV and HCV PCR analysis detected viral nucleic acid in three out of four and four out of six samples from viraemic patients undergoing endoscopy in Centre 1 during the period of improper manual washing. After proper cleaning was instituted, samples from nine out of nine HCV viraemic patients were negative. HIV RNA was detected in five of 14 samples taken from endoscopes after use on HIV positive patients but all post decontamination samples were negative. Detection of bacteria in washes from endoscope channels is a useful warning of a breakdown in decontamination practice. Inadequate brushing of internal channels may result in persistent HCV and HBV viral nucleic acid, the significance of which is not clear. These results reinforce the importance of adequate manual cleaning of endoscopes before chemical disinfection.

Molecular epidemiology of Burkholderia cepacia in two Australian cystic fibrosis centres.

Forty individual patient sputum isolates of Burkholderia cepacia from two Australian cystic fibrosis (CF) centres more than 100 km apart were genotyped using pulsed-field gel electrophoresis (PFGE) with XbaI restriction enzyme digestion. Hospital 1 had an endemic strain with 19 of 20 isolates being closely related. This centre does not implement an inpatient segregation policy for its paediatric patients who constitute the majority of those colonized with B. cepacia. Hospital 2 did not have a single endemic strain; there were two different sibling clusters and a third cluster involving a cohabiting couple, but all other patients had unique isolates. One patient at Hospital 2 carried an organism closely related to the endemic strain from Hospital 1. Hospital 2 practises segregation of colonized inpatients and also segregation external to the hospital. It would appear that no nosocomial spread of infection is occurring with this policy.

A national collaborative study of the in vitro activity of oral cephalosporins and loracarbef (LY 163892). Australian Group for the Study of Antimicrobial Resistance (AGAR).

A national collaborative study involving the laboratories of 17 Australian hospitals examined the in vitro activity of loracarbef, cefaclor, cephalexin, amoxycillin and amoxycillin/clavulanate against 2661 recently isolated common bacterial pathogens. Loracarbef was the most active agent against Escherichia coli (MIC90 = 1 mg/l) and had activity comparable to other agents against Klebsiella pneumoniae and Proteus mirabilis. Like the oral cephalosporins, it had no activity against species of Enterobacter and Serratia. beta-lactamase-producing Staphylococcus aureus and Haemophilus influenzae were moderately sensitive to loracarbef (MIC90 = 8 mg/l for both species). Streptococcus pneumoniae was moderately sensitive to loracarbef (MIC90 = 2 mg/l) but strains which were insensitive to penicillin were often highly resistant.

Multi-centre collaborative study for the in vitro evaluation of new macrolides dirithromycin and erythromycylamine. Australian Group for Antimicrobial Resistance (AGAR).

A national study was conducted to determine the in vitro activity of 2 newer macrolides, dirithromycin and erythromycylamine compared with that of erythromycin, tetracycline and penicillin. Nineteen major teaching hospitals participated in the study. Minimal Inhibitory Concentrations (MICs) were determined by agar dilution, mostly using Iso-Sensitest Agar and an inoculum of 10(4) cells per spot. 2284 clinically significant strains were isolated in late 1991 and early 1992, comprising 1736 Gram-positive cocci, 355 Haemophilus influenzae, 97 Moraxella catarrhalis, 32 Listeria monocytogenes, 25 Neisseria meningitidis and 39 Neisseria gonorrhoeae were tested. The study indicates that dirithromycin and erythromycylamine possess antibacterial activity equivalent to that of erythromycin against most Gram-positive cocci and M. catarrhalis. Strains resistant to erythromycin were also resistant to dirithromycin and to erythromycylamine. Tetracycline was as active as the macrolides against both penicillin-resistant and penicillin-susceptible strains of Staphylococcus aureus. Coagulase-negative penicillin-resistant staphylococci, compared with tetracycline, were relatively resistant to the macrolides. H. influenzae was less susceptible than the Gram-positive cocci.

Bacteremia and bacterascites after endoscopic sclerotherapy for bleeding esophageal varices and prevention by intravenous cefotaxime: a randomized trial.

Thirty-one patients were randomized during 39 episodes of bleeding to receive either 1 g of intravenous cefotaxime (19 patients) or no antibiotic (20 patients) immediately before emergency endoscopic sclerotherapy. Blood was obtained for culture before and at 5 minutes, 4 hours, and 24 hours after the procedure. Specimens for culture were taken from the endoscope tip and channel, water bottle, and injection needle after sclerotherapy. When ascites was present (5 patients in the antibiotic group, 7 in the control group), fluid was obtained by paracentesis before endoscopy and at 4 and 24 hours. Bacteremia occurred in 1 of 19 patients in the antibiotic group (5.3%), compared with 6 of 19 in the control group (31.6%; p = .04). The cultured organisms were oral flora and usually also contaminated the endoscope and needle. No bacteria were cultured from ascitic fluid in any patient nor was the ascitic fluid white cell count elevated. Clinical infection attributable to sclerotherapy did not develop in any patient. In conclusion, the frequency of bacteremia after endoscopic sclerotherapy for bleeding esophageal varices can be reduced by prophylactic administration of intravenous cefotaxime. However, this may not be clinically relevant, given the absence of bacterascites and infection in this study. These findings do not support the routine use of antibiotics before sclerotherapy.

Allergic fungal sinusitis presenting as a paranasal sinus tumour.

Allergic fungal rhinosinusitis is a rare complication of atopic upper airways disease which may present initially as an expansive tumour of the paranasal sinuses. This reported case was caused by the rare fungal pathogen Bipolaris hawiiensis and illustrates typical clinical and laboratory features of this disorder. Although the optimum management of allergic fungal sinusitis is controversial, combined therapy with surgical clearance, antifungal agents and corticosteroids produced a favourable outcome.

Treatment of tuberculosis in Australia.

The combination of isoniazid and rifampicin, initially accompanied by a third drug such as ethambutol, has become the standard treatment for pulmonary tuberculosis in Australia. Not all patients need admission to hospital but careful follow-up and encouragement of compliance with the regimen is important during the year of therapy which follows the diagnosis of the disease. Because of the higher incidence of drug resistance in disease acquired in Southeast Asia, a fourth drug, usually pyrazinamide, is added until the results of sensitivity testing are known. Pulmonary disease caused by environmental ("atypical") mycobacteria presents special problems in treatment because the infection usually complicates pre-existing lung disease; drug resistance is the rule; and there are no well controlled prospective trials to provide a rational basis for therapy.

Effect of antibiotic use on the incidence of cephalosporin resistance in two Australian hospitals.

The incidence of resistance of Gram-negative bacteria to three generations of cephalosporins was surveyed in two large hospitals with widely differing rates of cephalosporin usage. Overall resistance (MIC greater than 5 mg/l) of Enterobacteriaceae to cefotaxime in the hospital using large amounts of cephalosporins was 4% compared with 0.7% in the other. Enterobacter species accounted for most resistant isolates and resistant Enterobacter cloacae replaced sensitive strains in four patients given cefotaxime in 1983. The distribution of species colonizing intensive care areas was similar in both hospitals with cephalosporin-resistant Pseudomonas aeruginosa and Acinetobacter calcoaceticus predominating.

Measurement of IgM antibodies in the diagnosis of mycoplasma pneumonia.

The sera of 30 patients with complement-fixing antibodies to Mycoplasma pneumoniae (titres larger than or equal to 32) were treated with staphylococcal protein A. This procedure effectively removed 90 to 95% of the IgG antibodies. The Mycoplasma-specific antibodies in the treated sera could then be measured by a complement fixation test. This provides a useful test for distinguishing serological responses to recent Mycoplasma pneumoniae infections from anamnestic responses due to past exposure to Mycoplasma pneumoniae.