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John D Turnidge

Publications and source records attributed to John D Turnidge.

At least 19 recordsLinked to original sources
PubMed2006

Methicillin-resistant Staphylococcus aureus in the Australian community: an evolving epidemic.

OBJECTIVE: To describe antimicrobial resistance and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) isolated in community settings in Australia. DESIGN AND SETTING: Survey of S. aureus isolates collected prospectively Australia-wide between July 2004 and February 2005; results were compared with those of similar surveys conducted in 2000 and 2002. MAIN OUTCOME MEASURES: Up to 100 consecutive, unique clinical isolates of S. aureus from outpatient settings were collected at each of 22 teaching hospital and five private laboratories from cities in all Australian states and territories. They were characterised by antimicrobial susceptibilities (by agar dilution methods), coagulase gene typing, pulsed-field gel electrophoresis, multilocus sequence typing, SCCmec typing and polymerase chain reaction tests for Panton-Valentine leukocidin (PVL) gene. RESULTS: 2652 S. aureus isolates were collected, of which 395 (14.9%) were MRSA. The number of community-associated MRSA (CA-MRSA) isolates rose from 4.7% (118/2498) of S. aureus isolates in 2000 to 7.3% (194/2652) in 2004 (P = 0.001). Of the three major CA-MRSA strains, WA-1 constituted 45/257 (18%) of MRSA in 2000 and 64/395 (16%) in 2004 (P = 0.89), while the Queensland (QLD) strain increased from 13/257 (5%) to 58/395 (15%) (P = 0.0004), and the south-west Pacific (SWP) strain decreased from 33/257 (13%) to 26/395 (7%) (P = 0.01). PVL genes were detected in 90/195 (46%) of CA-MRSA strains, including 5/64 (8%) of WA-1, 56/58 (97%) of QLD, and 25/26 (96%) of SWP strains. Among health care-associated MRSA strains, all AUS-2 and AUS-3 isolates were multidrug-resistant, and UK EMRSA-15 isolates were resistant to ciprofloxacin and erythromycin (50%) or to ciprofloxacin alone (44%). Almost all (98%) of CA-MRSA strains were non-multiresistant. CONCLUSIONS: Community-onset MRSA continues to spread throughout Australia. The hypervirulence determinant PVL is often found in two of the most common CA-MRSA strains. The rapid changes in prevalence emphasise the importance of ongoing surveillance.

Australia↗
PubMed2006

Contemporary antimicrobial activity of triple antibiotic ointment: a multiphased study of recent clinical isolates in the United States and Australia.

Triple antibiotic ointment (TAO) containing neomycin, polymyxin B, and bacitracin was launched in the 1950s in the United States (USA) as a prescription product and then was used over the counter (OTC) since the 1970s (USA) to prevent superficial wound infections. In Australia, TAO has been restricted to prescription use. This study 1) determined cross-resistance patterns of neomycin compared with other aminoglycosides; 2) determined the level and trend of resistance to TAO and individual components especially versus mupirocin-resistant strains (USA); and 3) established the baseline TAO activity level against pathogens from Australia. A total of 200 strains (> or =50% gentamicin-resistant) from the United States were used for the cross-resistance study including Staphylococcus aureus (110), coagulase-negative staphylococci (CoNS; 50), Pseudomonas aeruginosa (10), Escherichia coli (20), and other Enterobacteriaceae (10) tested against TAO, bacitracin, polymyxin B, neomycin, amikacin, gentamicin, streptomycin, tobramycin, and mupirocin. Fifty gentamicin-resistant isolates from each year (1997-2002) were used to determine the activity of TAO over time. Baseline resistance rates of TAO among 300 Australian isolates (AGARS Program, 2002-2003) were also studied. Reference broth microdilution methods were used in all phases of this study. At a 1:100 dilution of the ointment concentration, TAO inhibited all CoNS, Pseudomonas aeruginosa, and Enterobacteriaceae isolates, and resistance to TAO among Staphylococcus aureus at this concentration was only 5% in the cross-resistance study. Patterns of susceptibility in the United States did not significantly vary from 1997 to 2002. Australian pathogens showed that TAO was 98% active against methicillin-resistant Staphylococcus aureus and 100% for Enterobacteriaceae, methicillin-susceptible S. aureus, CoNS, and P. aeruginosa, the rates equivalent to those observed in the United States. Mupirocin-resistant S. aureus (5%) and CoNS (47%) were all TAO-susceptible. All Gram-negative species were also mupirocin-resistant, but inhibited by neomycin and/or polymyxin B components of TAO. In conclusion, aminoglycoside resistance patterns differ significantly, and none of the commonly tested agents could accurately predict neomycin resistance. TAO resistance was rare in the United States after extensive OTC use and was not adversely influenced by decades of parenteral aminoglycoside use. Australian surveillance showed high levels of TAO susceptibility in sampled isolates as a baseline for possible OTC availability. TAO maintains a wider spectrum of activity compared with mupirocin and was usable against mupirocin-resistant Gram-positive strains.

Administration, Topical↗
PubMed2006

Colistin: the re-emerging antibiotic for multidrug-resistant Gram-negative bacterial infections.

Increasing multidrug resistance in Gram-negative bacteria, in particular Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, presents a critical problem. Limited therapeutic options have forced infectious disease clinicians and microbiologists to reappraise the clinical application of colistin, a polymyxin antibiotic discovered more than 50 years ago. We summarise recent progress in understanding the complex chemistry, pharmacokinetics, and pharmacodynamics of colistin, the interplay between these three aspects, and their effect on the clinical use of this important antibiotic. Recent clinical findings are reviewed, focusing on evaluation of efficacy, emerging resistance, potential toxicities, and combination therapy. In the battle against rapidly emerging bacterial resistance we can no longer rely entirely on the discovery of new antibiotics; we must also pursue rational approaches to the use of older antibiotics such as colistin.

Anti-Bacterial Agents↗
PubMed2005

A community-based intervention to reduce antibiotic use for upper respiratory tract infections in regional South Australia.

OBJECTIVE: To evaluate the effectiveness of a community-based and GP-based intervention in reducing unnecessary antibiotic prescribing for upper respiratory tract infections (URTIs) including sore throats, sinusitis and otitis media. DESIGN: Analysis of pharmacy dispensing data in June to October before (2000) and after (2001) the intervention, which commenced on 25 June 2001. SETTING AND PARTICIPANTS: Local consumers, health professionals, the Adelaide Southern Division of General Practice, the South Australian Government, and the local media in a rural region of South Australia, covering about 2000 square kilometres, with a population of over 20 000. INTERVENTION: Community dissemination of consumer information on antibiotic use for URTIs (including a local media campaign) and education of health professionals (including sessions with general practitioners at the four practices in the study area) on current Australian therapeutic guidelines for antibiotics, and a validated clinical scoring system for decision making in managing sore throat. MAIN OUTCOME MEASURES: Total dispensing data from local pharmacies for the months of June to October in 2000 and 2001, covering the six antibiotics considered most likely to be used for URTIs (amoxycillin, amoxycillin/clavulanic acid, cefaclor, doxycycline, erythromycin and roxithromycin). RESULTS: The dispensing of the six antibiotics reduced by 32% overall, from 77.1 to 52.9 defined daily doses per 1000 population per day, with statistically significant reductions in the range of 31%-70% for individual antibiotics; there was no reduction for amoxycillin with or without clavulanic acid. CONCLUSION: The intervention was associated with reduced dispensing of unnecessary antibiotics for URTIs.

Adolescent↗
PubMed2005

Regional variation in the prevalence of extended-spectrum beta-lactamase-producing clinical isolates in the Asia-Pacific region (SENTRY 1998-2002).

We examined the prevalence of extended-spectrum beta-lactamase (ESBL)-producing strains of Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, Proteus mirabilis, Citrobacter koseri, and Salmonella spp. that were isolated as part of the SENTRY Asia-Pacific Surveillance Program between 1998 and 2002. During the study period, a total of 6,388 strains were gathered from 17 medical centers in 7 countries and examined for ESBL production and hyperproduction of K. oxytoca chromosomal K1 beta-lactamase enzyme. High rates of confirmed ESBL-producing isolates were found in K. pneumoniae strains from Singapore (35.6%), followed by those from mainland China (30.7%), South Africa (28.1%), and the Philippines (21.9%), whereas the rates were less than 10% in Japan and Australia. ESBL-producing E. coli strains were also prominent in mainland China (24.5%), Hong Kong (14.3%), and Singapore (11.3%). ESBL-producing K. oxytoca were common in the Philippines (38.5%), Singapore (33.3%), and China (30.0%). Hyperproduction of K. oxytoca chromosomal K1 beta-lactamase enzyme was common in Australia and Japan. P. mirabilis strains from Singapore produced ESBL (17.9%) despite the low prevalence (0-8.1%) in other countries. Few ESBL-producing C. koseri and Salmonella spp. strains were found in Japan, Singapore, Taiwan, and South Africa. Although there was variation among countries in substrate preference, ceftazidime was more likely to detect presumptive ESBL phenotype in K. pneumoniae and aztreonam more likely in E. coli, whereas ceftriaxone was the best substrate for the confirmation of ESBL production. ESBL-producing strains showed high levels of co-resistance to aminoglycosides, tetracycline, trimethoprim-sulfamethoxazole, and ciprofloxacin. Imipenem retained activity against all ESBL-producing strains. Organisms expressing ESBLs are widely distributed in the Asia-Pacific region, although prevalence rates vary significantly.

Anti-Bacterial Agents↗
PubMed2005

Evaluation of colistin as an agent against multi-resistant Gram-negative bacteria.

Infections caused by multi-resistant Gram-negative bacteria, particularly Pseudomonas aeruginosa, are increasing worldwide. In patients with cystic fibrosis (CF), resistance in P. aeruginosa to numerous anti-pseudomonal agents is becoming common. The absence since 1995, of new substances active against resistant Gram-negative bacteria, has caused increasing concern. Colistin, an old antibiotic also known as polymyxin E, has attracted more interest recently because of its significant activity against multi-resistant P. aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae, and the low resistance rates to it. Because its use as an anti-pseudomonal agent was displaced by the potentially less toxic aminoglycosides in 1970s, our knowledge of this drug is limited. However, there has been a significant recent increase in the data gathered on colistin, focussing on its chemistry, antibacterial activity, mechanism of action and resistance, pharmacokinetics, pharmacodynamics and new clinical application. It is likely that colistin will be an important antimicrobial option against multi-resistant Gram-negative bacteria, for some years to come.

Acinetobacter baumannii↗
PubMed2004

Pharmacokinetics of colistin methanesulphonate and colistin in rats following an intravenous dose of colistin methanesulphonate.

OBJECTIVES: To determine the disposition of colistin methanesulphonate (CMS) and colistin following intravenous (iv) administration of CMS in rats. METHODS: Five rats received a single iv bolus of 15 mg/kg CMS. Plasma concentrations of CMS and of colistin formed by the hydrolysis of CMS were determined by HPLC. The pharmacokinetic parameters of CMS and colistin were calculated using non-compartmental analysis. RESULTS: Total body clearance, volume of distribution at steady state and terminal half-life of CMS averaged 11.7 mL/min/kg, 299 mL/kg and 23.6 min, respectively. The mean terminal half-life of colistin was 55.7 min. Approximately 60% of the dose was eliminated via the urine in 24 h and presented as a mixture of CMS and colistin. CONCLUSIONS: Colistin appeared in plasma soon after administration of CMS, indicating rapid conversion of CMS into colistin. CMS had a shorter terminal half-life than did colistin, indicating that the disposition of the colistin generated from CMS was rate-limited by its elimination. Most of the dose was recovered in urine, half in the form of colistin. The high percentage of colistin recovered in urine was believed to be formed by hydrolysis of CMS in the bladder and in the collection vessel, and/or conversion from CMS in the kidney.

Animals↗
PubMed2004

Evaluation of the contemporary occurrence rates of metallo-beta-lactamases in multidrug-resistant Gram-negative bacilli in Japan: report from the SENTRY Antimicrobial Surveillance Program (1998-2002).

Metallo-beta-lactamases (M beta L) were initially characterized in Japan, usually of the IMP-type, and found in Pseudomonas aeruginosa (PSA), Acinetobacter spp. (ACB), or Serratia marcescens (SM). The number of M beta L types has increased worldwide, but geographic dissemination within Japan has appeared limited. This study compares baseline levels of M beta L resistance from two 22-center studies (1996-1997) to the longitudinal sample (3 sites) of Japanese isolates from the SENTRY Antimicrobial Surveillance Program (1998-2002). All minimal inhibitory concentration results were determined by reference methods. A total of 26.8% PSA, 3.4% ACB, and 3.1% Enterobacteriaceae (enterobacters and SM) with resistance to monitored carbapenems (CARB) (minimal inhibitory concentration, > or =8 microg/mL) were screened for M beta L production by disk approximation tests (EDTA and 2-MPA inhibitors), CARB hydrolysis by enzyme extracts, and selected PCR primers for known M beta L types. All M beta L-positive strains (10) were sequenced to determine enzyme identification. Clonality in each center was determined by automated ribotyping and PFGE. The CARB susceptibility rates in PSA decreased (80.7% to 62.0%) over the monitored interval (1998-2002), but varied by medical center location. Among CARB-resistant isolates, 10.8% were attributed to M beta L strains (1.1% of all PSA tested). M beta L identification showed the following: five PSA (three IMP-1, two IMP-2), four SM (one IMP-1, two IMP-1 + OXA-1, and one IMP-11). Also a single ACB had an IMP-1. Eight of 10 M beta L isolations occurred between 2000 and 2002; four occurred in 2002. BRL42715, an AMP-C inhibitor, confirmed AMP-C-mediated resistance in 87.3% of PSA, and outer membrane protein changes were also discovered by membrane studies. Prior results (22 sites, 1997-1998) showed CARB resistance at 22.4-25.6% and 0.5-0.9% M beta Ls (IMP-1) overall; it was slightly elevated in this SENTRY Program sample. In conclusion, M beta L-producing strains from several species persist in Japan, but represent a distinct minority of all CARB-resistant strains (1998-2002). Although M beta L rates appear generally stable in Japan, continued surveillance for these mechanisms seems to be a prudent practice, because of the mobility of the genetic determinants and the emergence of novel enzyme types, especially among the Enterobacteriaceae.

Amino Acid Sequence↗
PubMed2004

Resistance development in community-acquired strains of methicillin-resistant Staphylococcus aureus: an in vitro study.

This study compares in vitro antimicrobial resistance development between strains of Staphylococcus aureus including newly described community-acquired methicillin-resistant strains (CA-MRSA). High-level resistance developed in all strains of S. aureus after exposure to rifampicin and gentamicin and in some strains after fusidic acid exposure, independent of methicillin resistance phenotype. Resistance did not develop after exposure to clindamycin, cotrimoxazole, ciprofloxacin, linezolid, or vancomycin. These results have important implications for therapy of CA-MRSA infections.

Community-Acquired Infections↗
PubMed2004

In-use efficacy of a chlorhexidine in alcohol surgical rub: a comparative study.

BACKGROUND: Although full surgical scrubs are performed prior to each case on an operating list, optimum regimens for hand cleaning have yet to be determined, and in-use efficacy evaluations are very limited. METHODS: A crossover study was undertaken comparing a chlorhexidine in detergent/alcohol regimen with povidine-iodine detergent scrub, within an orthopaedic operating environment. Depending on the skin asepsis regimen used, five surgical team members scrubbed or rubbed prior to each case for a complete operating list. Bactericidal efficacy was measured using the 'glove-juice' technique before and after hand asepsis, and at the completion of each case. RESULTS: The chlorhexidine regimen caused substantial and sustained reductions in hand bacterial counts (>50-fold prior to case 1) during surgical cases. Application of alcoholic chlorhexidine prior to each subsequent case reduced bacterial counts to the same level as the original scrub. In contrast, the povidine-iodine scrub reduced counts <3-fold prior to the first case and <2-fold in subsequent cases. The chlorhexidine regimen also resulted in persistent bactericidal effects between cases, as counts prior to application of cases 2 and higher were significantly lower than prior to case 1 (>7-fold for case 2 vs case 1). CONCLUSIONS: The chlorhexidine regimen demonstrated excellent bactericidal efficacy throughout an operating list, and was superior to povidine-iodine scrubbing in all aspects. The alcoholic chlorhexidine regimen is simpler and should have wide surgical application.

2-Propanol↗
PubMed2003

Antimicrobial resistance in Staphylococcus aureus in Australian teaching hospitals, 1989-1999.

An annual survey of antimicrobial resistance in clinical isolates of Staphylococcus aureus was conducted in 21 Australian teaching hospital microbiology laboratories in eight major cities from 1989 to 1999. A total of 19,000 isolates were tested for susceptibility to 18 antimicrobials, with 3795 being methicillin-resistant (MRSA). Resistance to ciprofloxacin in MRSA increased from 4.9% to 75.9%. The proportion of MRSA resistant to erythromycin decreased significantly (99.0%-88.9%), as did that to trimethoprim (98.4%-82.4%) and to tetracycline (96.5%-80.1%). The proportion of MRSA isolated increased in Sydney, Melbourne, Canberra, Adelaide, Perth, and Darwin, but not in Brisbane. The proportion in Hobart peaked in 1994. MRSA in Perth were predominantly non-multiresistant (nmMRSA) throughout the survey (i.e., resistant to less than three of eight indicator antibiotics) due mainly to local strains that originated in the community. The proportion of nmMRSA increased to modest levels in the other cities. In eastern cities, this was due to the appearance of strains closely related to nmMRSA seen in other countries of the southwestern Pacific.

Anti-Infective Agents↗
PubMed2003

Multicentre evaluation of the in vitro activity of linezolid in the Western Pacific.

Multiresistance to antimicrobial agents is common in staphylococci and pneumococci isolates in the Western Pacific region. The activity of linezolid, a new oxazolidinone, was evaluated against a spectrum of Gram-positive species collected in the region. Eighteen laboratories from six countries in the Western Pacific examined the linezolid susceptibility of 2143 clinical isolates of Staphylococcus aureus, coagulase-negative staphylococci (CoNS) and Enterococcus spp. using broth microdilution or disc diffusion methodology. For Streptococcus pneumoniae (n = 351) and other streptococci (n = 83), Etest (AB Biodisk, Solna, Sweden) strips were used. Results were compared with other common and important antimicrobials. Linezolid-resistant strains were not detected among streptococci or staphylococci, including a significant proportion of S. aureus strains that were multiresistant. Almost all enterococci, including 14 vancomycin-resistant Enterococcus faecium, were linezolid susceptible. A small proportion of enterococci (0.8%) were intermediate to linezolid, and one strain of Enterococcus faecalis had a zone diameter of 20 mm (resistant). The linezolid MIC ranges (MIC(90)) of those strains tested by broth microdilution or Etest were: 1-4 mg/L (2 mg/L) for S. aureus, 0.5-4 mg/L (2 mg/L) for CoNS, 0.5-4 mg/L (2 mg/L) for Enterococcus spp., 0.12-2 mg/L (1 mg/L) for S. pneumoniae and 0.25-2 mg/L (1 mg/L) for Streptococcus spp. There was no difference in linezolid susceptibility between countries or between multiresistant and susceptible strains of each species monitored.

Acetamides↗
PubMed2003

Stability of colistin and colistin methanesulfonate in aqueous media and plasma as determined by high-performance liquid chromatography.

The stabilities of colistin and colistin methanesulfonate (CMS) in different aqueous media were studied by specific high-performance liquid chromatography (HPLC) methods. Colistin was stable in water at 4 and 37 degrees C for up to 60 days and 120 h, respectively. However, degradation was observed when colistin was stored in isotonic phosphate buffer (0.067 M, pH 7.4) and human plasma at 37 degrees C. The stability of CMS from three different sources in water was explored by strong-anion-exchange (SAX) HPLC for CMS and by measuring the concentrations of colistin formed from the hydrolysis of CMS. The peaks of CMS in SAX HPLC disappeared almost completely after 12 h at 37 degrees C, but appeared to remain intact for up to 2 days at 4 degrees C. Over the same period, there was no formation of colistin at 4 degrees C. In water, phosphate buffer, and plasma, there was rapid formation of colistin within 24 to 48 h at 37 degrees C from the three sources of CMS. The hydrolysis products were assumed to be a complex mixture of many different sulfomethyl derivatives, including colistin. The stability of a fourth source of CMS in Mueller-Hinton broth examined during 30 min at 37 degrees C revealed no formation of colistin. Along with previous microbiological studies, this suggested that different sulfomethyl CMSs possess intrinsic antibacterial activity. These results will be helpful for understanding the pharmacokinetics and pharmacodynamics of colistin and CMS in humans and animals.

Anti-Bacterial Agents↗
PubMed2003

Use of high-performance liquid chromatography to study the pharmacokinetics of colistin sulfate in rats following intravenous administration.

The pharmacokinetics of colistin was investigated using specific high-performance liquid chromatography (HPLC) to measure the concentrations of colistin and colistin A and B in plasma and urine in five rats after administration of an intravenous bolus of 1 mg of colistin sulfate/kg of body weight. There were differences in the pharmacokinetic behaviors of unbound colistin A and B. This is the first report of the use of HPLC to study the pharmacokinetics of colistin and its two major components.

Animals↗