A review of the Royal Perth Hospital Bali experience: an infection control perspective

Thirty five patients were transferred to Royal Perth Hospital (RPH) after the Bali bombings. The patients had severe burn injuries and were considered to be at high-risk of both the carriage and acquisition of multi-resistant organisms (MROs). Whilst seeking to protect the Bali patients with a comprehensive infection control response, we also sought to protect other high-risk patients from nosocomial acquisition of MROs. MROs were detected from 25 (82%) of the 29 Bali patients admitted to RPH. Bali patients were colonised, or infected, with one or more of the following MROs: multi-resistant Acinetobacter baumannii (MRAB) (19 patients), extended-spectrum ß-lactamase (ESBL) producing Gram-negative bacteria (15 patients), vancomycin-resistant enterococci (VRE) (nine patients), multi-resistant Pseudomonas aeruginosa (MRPA) (six patients), multi-resistant Chryseobacterium sp. (four patients), and methicillin-resistant Staphylococcus aureus (MRSA) (three patients). Five Bali patients developed a total of eight bacteraemic episodes, with MRPA sepsis contributing to death in two patients. Since the Bali bombings horizontal transmission of Bali MROs has occurred in 41 non-Bali patients in RPH. MRPA has had the greatest clinical impact. Eight non-Bali patients developed a total of 11 bacteraemic episodes, with MRPA sepsis contributing to death in four patients. However, apart from MRPA, we have now controlled transmission of the other MROs in RPH.

The emergency response to the Bali disaster required strong leadership, good communication and multi-disciplinary teamwork. The infection control strategy contributed to good outcomes for most Bali bombing patients. However, many patients within the Bali cohort were heavily colonised with MROs, and some developed invasive infection. Subsequent nosocomial transmission of these MROs to non-Bali patients has been a legacy of the Bali tragedy.

Eradication of a Large Outbreak of a Single Strain of vanB Vancomycin-ResistantEnterococcus faeciumat a Major Australian Teaching Hospital

Objective:

To demonstrate that nosocomial transmission of vancomycin-resistant enterococci (VRE) can be terminated and endemicity prevented despite widespread dissemination of an epidemic strain in a large tertiary-care referral hospital.

Interventions:

Two months after the index case was detected in the intensive care unit, 68 patients became either infected or colonized with an epidemic strain of vanB vancomycin-resistantEnterococcus faeciumdespite standard infection control procedures. The following additional interventions were then introduced to control the outbreak: (1) formation of a VRE executive group; (2) rapid laboratory identification (30 to 48 hours) using culture and polymerase chain reaction detection ofvanA andvanBresistance genes; (3) mass screening of all hospitalized patients with isolation of carriers and cohorting of contacts; (4) environmental screening and increased cleaning; (5) electronic flagging of medical records of contacts; and (6) antibiotic restrictions (third-generation cephalosporins and vancomycin).

Results:

A total of 19,658 patient and 24,396 environmental swabs were processed between July and December 2001. One hundred sixty-nine patients in 23 wards were colonized with a single strain of vanB vancomycin-resistantE. faecium.Introducing additional control measures rapidly brought the outbreak under control. Hospital-wide screening found 39 previously unidentified colonized patients, with only 7 more nonsegregat-ed patients being detected in the next 2 months. The outbreak was terminated within 3 months at a cost of $2.7 million (Australian dollars).

Conclusion:

Despite widespread dissemination of VRE in a large acute care facility, eradication was achievable by a well-resourced, coordinated, multifaceted approach and was in accordance with good clinical governance.

Increased EMRSA-15 health-care worker colonization demonstrated in retrospective review of EMRSA hospital outbreaks

Background

Health care worker (HCW) colonization with methicillin resistant Staphylococcus aureus (MRSA) is a documented cause of hospital outbreaks and contributes to ongoing transmission. At Royal Perth Hospital (RPH) it had been anecdotally noted that the increasing prevalence of EMRSA-15 appeared to be associated with increased HCW colonization compared with Aus2/3-EMRSA. Hence we compared HCW colonization rates during outbreaks of EMRSA-15 and Aus2/3-EMRSA at a single institution.

Methods

We performed a retrospective review of EMRSA-15 and Aus2/3-EMRSA outbreaks from 2000–2009 at RPH, a quaternary hospital in Western Australia. Outbreak files were reviewed and relevant data extracted.

Results

Ten EMRSA-15 outbreaks were compared with seven Aus2/3 outbreaks. The number of patients colonized was similar between EMRSA-15 and Aus2/3-EMRSA outbreaks (median 7 [range 3–20] and 11 [5–26], respectively; P = 0.07) but the number of HCWs colonized was significantly higher in EMRSA-15 outbreaks compared to Aus2/3-EMRSA outbreaks (median 4 [range 0–15] and 2 [1-3], respectively; P = 0.013). The percentage of HCWs colonized was also higher in EMRSA-15 outbreaks versus Aus2/3-EMRSA outbreaks (median 3.4% [range 0–5.5%] and 0.81% [0.56–2.2%], respectively; P = 0.013).

Conclusions

This study demonstrates a higher level of HCW colonization during EMRSA-15 outbreaks compared with Aus2/3-EMRSA outbreaks. This finding suggests that MRSA vary in their ability to colonize HCWs and contribute to outbreaks. MRSA type should be determined during outbreaks and future research should investigate the mechanisms by which EMRSA-15 contributes to increased HCW colonization.

Knowing prior methicillin-resistant Staphylococcus aureus (MRSA) infection or colonization status increases the empirical use of glycopeptides in MRSA bacteraemia and may decrease mortality

To compare the management and outcome of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in patients known to be MRSA-colonized/infected (C-patients) with the management and outcome in those not known to be colonized/infected (NC-patients), we conducted a 10-year retrospective review of MRSA bacteraemia in an adult tertiary hospital. Clinical data were obtained by chart review, and mortality data from linked databases. Prior MRSA colonization/infection status was available to treating clinicians at the time of the bacteraemia as a 'Micro-Alert' tag on the patient's labels, in medical charts, and in electronic information systems. C-patients accounted for 35.4% of all MRSA bacteraemia episodes. C-patients were more likely to be indigenous, to be diabetic, or to have a history of previous S. aureus infection. Markers of illness severity (Simplified Acute Physiology Score (SAPS)-II, need for admission to the intensive-care unit, length of stay, and metastatic seeding) were similar in both groups. Empirical therapy included a glycopeptide in 49.3% of C-patients vs. 18.9% of NC-patients (p <0.01), and contained an antibiotic to which the MRSA isolate tested susceptible in vitro in 56.7% of C-patients vs. 45.1% of NC-patients (p 0.13). All-cause 7-day and 30-day mortality were 7.5% vs. 18.9% (p 0.04), and 22.4% vs. 31.1% (p 0.20), in the C-patient and NC-patient groups, respectively. Knowing MRSA colonization status was significantly associated with lower 30-day mortality in Cox regression analysis (p <0.01). These data suggest that mortality from MRSA bacteraemia is lower in C-patients, which may reflect the earlier use of glycopeptides. The low use of empirical glycopeptides in septic patients known to be previously MRSA-colonized/infected may represent a missed opportunity for infection control to positively impact on clinical management.

Australian Group on Antimicrobial Resistance Hospital-onset Staphylococcus aureus Surveillance Programme annual report, 2011

In 2011, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Twenty-nine microbiology laboratories from all states and mainland territories participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2® antimicrobial susceptibility card (AST-P612 card). Nationally, the proportion of S. aureus that were methicillin-resistant S. aureus (MRSA) was 30.3%; ranging from 19.9% in Western Australia to 36.8% in New South Wales/Australian Capital Territory. Resistance to the non-ß-lactam antimicrobials was common except for rifampicin, fusidic acid, high-level mupirocin and daptomycin. No resistance was detected for vancomycin, teicoplanin or linezolid. Antibiotic resistance in methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (13.2%) and there was no resistance to vancomycin, teicoplanin or linezolid. Inducible clindamycin resistance was the norm for erythromycin resistant, clindamycin intermediate/susceptible S. aureus in Australia with 90.6% of MRSA and 83.1% of MSSA with this phenotype having a positive double disc diffusion test (D-test). The proportion of S. aureus characterised as being healthcare-associated MRSA (HA-MRSA) was 18.2%, ranging from 4.5% in Western Australia to 28.0% in New South Wales/Australian Capital Territory. Four HA-MRSA clones were characterised and 98.8% of HA-MRSA isolates were classified as either ST22-IV [2B] (EMRSA-15) or ST239-III [3A] (Aus-2/3 EMRSA). Multiclonal community-associated MRSA (CA-MRSA) accounted for 11.7% of all S. aureus. In Australia, regional variation in resistance is due to the differential distribution of MRSA clones between regions, particularly for the major HA-MRSA clone, ST239-III [3A] (Aus-2/3 EMRSA), which is resistant to multiple non-ß-lactam antimicrobials.

The molecular epidemiology of the highly virulent ST93 Australian community Staphylococcus aureus strain

In Australia the PVL-positive ST93-IV [2B], colloquially known as "Queensland CA-MRSA" has become the dominant CA-MRSA clone. First described in the early 2000s, ST93-IV [2B] is associated with skin and severe invasive infections including necrotizing pneumonia. A singleton by multilocus sequence typing (MLST) eBURST analysis ST93 is distinct from other S. aureus clones. To determine if the increased prevalence of ST93-IV [2B] is due to the widespread transmission of a single strain of ST93-IV [2B] the genetic relatedness of 58 S. aureus ST93 isolated throughout Australia over an extended period were studied in detail using a variety of molecular methods including pulsed-field gel electrophoresis, spa typing, MLST, microarray DNA, SCCmec typing and dru typing. Identification of the phage harbouring the lukS-PV/lukF-PV Panton Valentine leucocidin genes, detection of allelic variations in lukS-PV/lukF-PV, and quantification of LukF-PV expression was also performed. Although ST93-IV [2B] is known to have an apparent enhanced clinical virulence, the isolates harboured few known virulence determinants. All PVL-positive isolates carried the PVL-encoding phage ΦSa2USA and the lukS-PV/lukF-PV genes had the same R variant SNP profile. The isolates produced similar expression levels of LukF-PV. Although multiple rearrangements of the spa sequence have occurred, the core genome in ST93 is very stable. The emergence of ST93-MRSA is due to independent acquisitions of different dru-defined type IV and type V SCCmec elements in several spa-defined ST93-MSSA backgrounds. Rearrangement of the spa sequence in ST93-MRSA has subsequently occurred in some of these strains. Although multiple ST93-MRSA strains were characterised, little genetic diversity was identified for most isolates, with PVL-positive ST93-IVa [2B]-t202-dt10 predominant across Australia. Whether ST93-IVa [2B] t202-dt10 arose from one PVL-positive ST93-MSSA-t202, or by independent acquisitions of SCCmec-IVa [2B]-dt10 into multiple PVL-positive ST93-MSSA-t202 strains is not known.

A multidrug-resistant Staphylococcus epidermidis clone (ST2) is an ongoing cause of hospital-acquired infection in a Western Australian hospital

We report the molecular epidemiology of 27 clinical multidrug-resistant Staphylococcus epidermidis (MDRSE) isolates collected between 2003 and 2007 in an Australian teaching hospital. The dominant genotype (sequence type 2 [ST2]) accounted for 85% of the isolates tested and was indistinguishable from an MDRSE genotype identified in European hospitals, which may indicate that highly adaptable health care-associated genotypes of S. epidermidis have emerged and disseminated worldwide in the health care setting.

Evolution and diversity of community-associated methicillin-resistant Staphylococcus aureus in a geographical region

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was first reported in remote regions of Western Australia and is now the predominant MRSA isolated in the state. The objective of this study is to determine the genetic relatedness of Western Australian CA-MRSA clones within different multilocus sequence type (MLST) clonal clusters providing an insight into the frequency of S. aureus SCCmec acquisition within a region.

RESULTS

The CA-MRSA population in Western Australia is genetically diverse consisting of 83 unique pulsed-field gel electrophoresis strains from which 46 MLSTs have been characterised. Forty five of these sequence types are from 18 MLST clonal clusters and two singletons. While SCCmec IV and V are the predominant SCCmec elements, SCCmec VIII and several novel and composite SCCmec elements are present. The emergence of MRSA in diverse S. aureus clonal clusters suggests horizontal transmission of the SCCmec element has occurred on multiple occasions. Furthermore DNA microarray and spa typing suggests horizontal transfer of SCCmec elements has also occurred within the same CC. For many single and double locus variant CA-MRSA clones only a few isolates have been detected.

CONCLUSIONS

Although multiple CA-MRSA clones have evolved in the Western Australian community only three clones have successfully adapted to the Western Australian community environment. These data suggest the successful evolution of a CA-MRSA clone may not only depend on the mobility of the SCCmec element but also on other genetic determinants.

Prevalence of nasal methicillin-resistant Staphylococcus aureus colonization in healthcare workers in a Western Australian acute care hospital

Due to a longstanding comprehensive "search and destroy policy", methicillin-resistant Staphylococcus aureus (MRSA) is not endemic in Western Australian (WA) acute care hospitals. As the prevalence of MRSA in the community has increased, healthcare workers (HCW) are at risk of importing MRSA into hospitals. We aimed to determine the prevalence of and risk factors for nasal MRSA colonization in our HCW population. A period prevalence study was conducted at an 850-bed tertiary hospital. Basic demographics and a nasal swab were obtained. A total of 1,542 HCWs employed in our centre were screened for MRSA, of whom 3.4% (n = 52) were colonized. MRSA colonization was more common in patient care assistants (6.8%) and nurses (5.2%) than in allied health professionals (1.7%) and doctors (0.7%) (p < 0.01). Working in "high-risk" wards that cared for MRSA colonized/infected patients was the strongest risk factor for HCW MRSA colonization (p < 0.001). ST1-IV and ST78-IV (the most common community clones in the region) were the most frequently identified clones. In conclusion, MRSA colonization of HCWs occurs primarily in HCWs caring for patients colonized or infected with MRSA. Surveillance screening of HCWs should be regularly performed on wards with patients with high MRSA colonization prevalence to prevent further spread in the hospital.

Antibiotic choice may not explain poorer outcomes in patients with Staphylococcus aureus bacteremia and high vancomycin minimum inhibitory concentrations

BACKGROUND

There are concerns about reduced efficacy of vancomycin in patients with Staphylococcus aureus bacteremia (SAB), especially when the minimum inhibitory concentration (MIC) nears the upper limit of the susceptible range.

METHODS

We examined the relationship between antibiotic treatment, 30-day mortality, and microbiologic parameters in a large Australasian cohort of patients with SAB.

RESULTS

We assessed 532 patients with SAB from 8 hospitals. All patients with methicillin-resistant S. aureus (MRSA) bacteremia were treated with vancomycin, and patients with methicillin-susceptible S. aureus (MSSA) bacteremia received either flucloxacillin or vancomycin. Increasing vancomycin MIC was associated with increased mortality in vancomycin-treated patients. However, even in patients with MSSA bacteremia treated with flucloxacillin, mortality was also higher if the vancomycin Etest MIC of their isolate was >1.5 μg/mL, compared with those with lower MIC isolates (26.8% vs 12.2%; P < .001). After adjustment in a multivariate model, age, hospital-onset SAB and vancomycin MIC were independently associated with mortality, but methicillin resistance and antibiotic choice were not.

CONCLUSIONS

We have confirmed an association between higher vancomycin MIC and increased mortality in patients with SAB, but surprisingly this relationship was not related to the antibiotic treatment received, suggesting that the use of vancomycin per se is not responsible for the poorer outcome.

Antimicrobial susceptibility of Staphylococcus aureus isolated from hospital inpatients, 2009: report from the Australian Group on Antimicrobial Resistance

In 2009, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Thirty medical microbiology laboratories from each state and mainland territory participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2 (AST-P579 card) and by Etest for daptomycin. Nationally, the proportion of S. aureus that were MRSA was 33.6%, ranging from 27.3% in South Australia to 41.4% in New South Wales/Australian Capital Territory. Resistance to the non-beta-lactam antimicrobials was common except for rifampicin, fusidic acid, daptomycin and high-level mupirocin. No resistance was detected for vancomycin, teicoplanin, quinupristin-dalfopristin or linezolid. Resistance in the methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (12%) and absent for vancomycin, teicoplanin, daptomycin, quinupristin-dalfopristin and linezolid. The proportion of methicillin resistant S. aureus (MRSA) has remained stable since the first AGAR inpatient survey in 2005 yet during the same time frame resistance to many antimicrobials, in particular tetracycline, trimethoprim-sulphamethoxazole and gentamicin, has significantly decreased. This suggests that non-multi-resistant community-associated MRSA (CA-MRSA) clones are becoming more common in the hospital setting and replacing the long-established multi-resistant clones such as ST239-III (Aus 2/3 EMRSA). Given hospital outbreaks of CA-MRSA are thought to be extremely rare it is most likely that patients colonised at admission with CA-MRSA have become infected with the colonising strain during their hospital stay.

In vitro activity of doripenem and other carbapenems against contemporary Gram-negative pathogens isolated from hospitalised patients in the Asia-Pacific region: results of the COMPACT Asia-Pacific Study

The Comparative Activity of Carbapenems Testing (COMPACT) Study was designed to determine the in vitro potency of doripenem compared with imipenem and meropenem against a large number of contemporary Gram-negative pathogens from more than 100 centres across Europe and the Asia-Pacific region and to assess the reliability of Etest methodology for doripenem minimum inhibitory concentration (MIC) determination against these pathogens. Data from eight countries within the Asia-Pacific region, which collected 1612 bacterial isolates, are presented here. Etest methodology was found to be a reliable method for MIC determination. Doripenem showed in vitro activity similar to or better than meropenem and at least four-fold better than imipenem against Enterobacteriaceae. Against Pseudomonas aeruginosa, doripenem was also the most active of the three carbapenems in vitro. However, in vitro results do not necessarily correlate with clinical outcome.

Differentiation of clonal complex 59 community-associated methicillin-resistant Staphylococcus aureus in Western Australia

Clonal complex 59 (CC59) community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains were characterized using pulsed-field gel electrophoresis, spa typing, multilocus sequence typing, diagnostic DNA microarrays, and PCRs targeting staphylococcal cassette chromosome mec (SCCmec) elements and Panton-Valentine leukocidin (PVL). Six distinct groups within CC59 were characterized. At least seven different variants of SCCmec elements were identified (IVa [2B], IVb [2B], IVd [2B], IV variant [2B], IVa [2B&5], V variant [5C2], and V [5C2&5]). (The structural type is indicated by a Roman numeral, with a lowercase letter indicating the subtype, and the ccr complex and the mec complex are indicated by an Arabic numeral and an uppercase letter, respectively. Where there is an extra ccr element, this is indicated by "&" and an Arabic numeral designating the ccr type.) The first group is similar to the American sequence type 59 (ST59) MRSA-IV CA-MRSA strain USA1000. The second group includes a PVL-negative ST87 strain with an SCCmec element of subtype IVb (2B). The third group comprises PVL-variable ST59 MRSA-IV strains harboring multiple SCCmec IV subtypes. PVL-negative ST59 MRSA strains with multiple or composite SCCmec elements (IVa [2B&5]) form the fourth group. Group 5 corresponds to the internationally known "Taiwan clone," a PVL-positive strain with a variant SCCmec element (V [5C2&5]). This strain proved to be the most common CC59 MRSA strain isolated in Western Australia. Finally, group 6 encompasses the ST59 MRSA-V variant (5C2). The differentiation of CC59 into groups and strains indicates a rapid evolution and spread of SCCmec elements. Observed differences between groups of strains as well as intrastrain variability within a group facilitate the tracing of their spread.

Community-acquired pneumonia due to pandemic A(H1N1)2009 influenzavirus and methicillin resistant Staphylococcus aureus co-infection

BACKGROUND

Bacterial pneumonia is a well described complication of influenza. In recent years, community-onset methicillin-resistant Staphylococcus aureus (cMRSA) infection has emerged as a contributor to morbidity and mortality in patients with influenza. Since the emergence and rapid dissemination of pandemic A(H1N1)2009 influenzavirus in April 2009, initial descriptions of the clinical features of patients hospitalized with pneumonia have contained few details of patients with bacterial co-infection.

METHODOLOGY/PRINCIPAL FINDINGS

Patients with community-acquired pneumonia (CAP) caused by co-infection with pandemic A(H1N1)2009 influenzavirus and cMRSA were prospectively identified at two tertiary hospitals in one Australian city during July to September 2009, the period of intense influenza activity in our region. Detailed characterization of the cMRSA isolates was performed. 252 patients with pandemic A(H1N1)2009 influenzavirus infection were admitted at the two sites during the period of study. Three cases of CAP due to pandemic A(H1N1)2009/cMRSA co-infection were identified. The clinical features of these patients were typical of those with S. aureus co-infection or sequential infection following influenza. The 3 patients received appropriate empiric therapy for influenza, but inappropriate empiric therapy for cMRSA infection; all 3 survived. In addition, 2 fatal cases of CAP caused by pandemic A(H1N1)2009/cMRSA co-infection were identified on post-mortem examination. The cMRSA infections were caused by three different cMRSA clones, only one of which contained genes for Panton-Valentine Leukocidin (PVL).

CONCLUSIONS/SIGNIFICANCE

Clinicians managing patients with pandemic A(H1N1)2009 influenzavirus infection should be alert to the possibility of co-infection or sequential infection with virulent, antimicrobial-resistant bacterial pathogens such as cMRSA. PVL toxin is not necessary for the development of cMRSA pneumonia in the setting of pandemic A( H1N1) 2009 influenzavirus co-infection.

Population dynamics of methicillin-susceptible and -resistant Staphylococcus aureus in remote communities

Objectives

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was first reported in remote regions of Western Australia (WA) in 1992 and is now the predominant MRSA isolated in the State. To gain insights into the emergence of CA-MRSA, 2146 people living in 11 remote WA communities were screened for colonization with S. aureus.

Methods

Antibiogram analysis, contour-clamped homogeneous electric field electrophoresis, multilocus sequence typing, Panton–Valentine leucocidin determinant detection and accessory genetic regulator typing were performed to characterize the isolates. MRSA was further characterized by staphylococcal cassette chromosome mec typing.

Results

The S. aureus population consisted of 13 clonal complexes and two Singleton lineages together with 56 sporadic isolates. Five lineages contained MRSA; however, these were not the predominant methicillin-susceptible S. aureus (MSSA) lineages. There was greater diversity amongst the MSSA while the MRSA appeared to have emerged clonally following acquisition of the staphylococcal cassette chromosome mec. Three MRSA lineages were considered to have been endemic in the communities and have subsequently become predominant lineages of CA-MRSA in the wider WA community. People colonized with MSSA tended to harbour clones of a different genetic lineage at each anatomical site while people colonized with MRSA tended to harbour clones of the same lineage at each site. Overall, the isolates were resistant to few antimicrobials.

Conclusions

Although the evidence suggests that in WA CA-MRSA strains arose in remote communities and have now disseminated into the wider community, there is no evidence that they arose from the predominant MSSA clones in these communities.

Prevalence of MRSA strains among Staphylococcus aureus isolated from outpatients, 2006

Biennial community-based Staphylococcus aureus antimicrobial surveillance programs have been performed by the Australian Group for Antimicrobial Resistance (AGAR) since 2000. Over this time the percentage of S. aureus identified as methicillin resistant has increased significantly from 10.3% in 2000 to 16% in 2006. This increase has occurred throughout Australia and has been due to the emergence of community-associated MRSA (CA-MRSA) clones. However, healthcare associated MRSA were still predominant in New South Wales/Australian Capital Territory and Victoria/Tasmania. In the 2006 survey CA-MRSA accounted for 8.8% of community-onset S. aureus infections. Although multiple CA-MRSA clones were characterised, the predominate clone identified was Queensland (Qld) MRSA (ST93-MRSA-IV) a Panton-Valentine leukocidin (PVL) positive MRSA that was first reported in Queensland and northern New South Wales in 2003 but has now spread throughout Australia. Several international PVL-positive CA-MRSA clones were also identified including USA300 MRSA (ST8-MRSA-IV). In addition, PVL was detected in an EMRSA-15 (ST22-MRSA-IV) isolate; a hospital associated MRSA clone that is known to be highly transmissible in the healthcare setting. With the introduction of the international clones and the transmission of Qld MRSA throughout the country, over 50% of CA-MRSA in Australia are now PVL positive. This change in the epidemiology of CA-MRSA in the Australian community will potentially result in an increase in skin and soft tissue infections in young Australians. As infections caused by these strains frequently results in hospitalisation their emergence is a major health concern.

Outbreak of invasive methicillin-resistant Staphylococcus aureus infection associated with acupuncture and joint injection

OBJECTIVE

To describe an outbreak of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection after percutaneous needle procedures (acupuncture and joint injection) performed by a single medical practitioner.

SETTING

A medical practitioner's office and 4 hospitals in Perth, Western Australia.

PATIENTS

Eight individuals who developed invasive MRSA infection after acupuncture or joint injection performed by the medical practitioner.

METHODS

We performed a prospective and retrospective outbreak investigation, including MRSA colonization surveillance, environmental sampling for MRSA, and detailed molecular typing of MRSA isolates. We performed an infection control audit of the medical practitioner's premises and practices and administered MRSA decolonization therapy to the medical practitioner.

RESULTS

Eight cases of invasive MRSA infection were identified. Seven cases occurred as a cluster in May 2004; another case (identified retrospectively) occurred approximately 15 months earlier in February 2003. The primary sites of infection were the neck, shoulder, lower back, and hip: 5 patients had septic arthritis and bursitis, and 3 had pyomyositis; 3 patients had bacteremia, including 1 patient with possible endocarditis. The medical practitioner was found to be colonized with the same MRSA clone [ST22-MRSA-IV (EMRSA-15)] at 2 time points: shortly after the first case of infection in March 2003 and again in May 2004. After the medical practitioner's premises and practices were audited and he himself received MRSA decolonization therapy, no further cases were identified.

CONCLUSIONS

This outbreak most likely resulted from a breakdown in sterile technique during percutaneous needle procedures, resulting in the transmission of MRSA from the medical practitioner to the patients. This report demonstrates the importance of surveillance and molecular typing in the identification and control of outbreaks of MRSA infection.

SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia

BACKGROUND

Existing severity assessment tools, such as the pneumonia severity index (PSI) and CURB-65 (tool based on confusion, urea level, respiratory rate, blood pressure, and age >or=65 years), predict 30-day mortality in community-acquired pneumonia (CAP) and have limited ability to predict which patients will require intensive respiratory or vasopressor support (IRVS).

METHODS

The Australian CAP Study (ACAPS) was a prospective study of 882 episodes in which each patient had a detailed assessment of severity features, etiology, and treatment outcomes. Multivariate logistic regression was performed to identify features at initial assessment that were associated with receipt of IRVS. These results were converted into a simple points-based severity tool that was validated in 5 external databases, totaling 7464 patients.

RESULTS

In ACAPS, 10.3% of patients received IRVS, and the 30-day mortality rate was 5.7%. The features statistically significantly associated with receipt of IRVS were low systolic blood pressure (2 points), multilobar chest radiography involvement (1 point), low albumin level (1 point), high respiratory rate (1 point), tachycardia (1 point), confusion (1 point), poor oxygenation (2 points), and low arterial pH (2 points): SMART-COP. A SMART-COP score of >or=3 points identified 92% of patients who received IRVS, including 84% of patients who did not need immediate admission to the intensive care unit. Accuracy was also high in the 5 validation databases. Sensitivities of PSI and CURB-65 for identifying the need for IRVS were 74% and 39%, respectively.

CONCLUSIONS

SMART-COP is a simple, practical clinical tool for accurately predicting the need for IRVS that is likely to assist clinicians in determining CAP severity.

The etiology of community-acquired pneumonia in Australia: why penicillin plus doxycycline or a macrolide is the most appropriate therapy

BACKGROUND

Available data on the etiology of community-acquired pneumonia (CAP) in Australia are very limited. Local treatment guidelines promote the use of combination therapy with agents such as penicillin or amoxycillin combined with either doxycycline or a macrolide.

METHODS

The Australian CAP Study (ACAPS) was a prospective, multicenter study of 885 episodes of CAP in which all patients underwent detailed assessment for bacterial and viral pathogens (cultures, urinary antigen testing, serological methods, and polymerase chain reaction). Antibiotic agents and relevant clinical outcomes were recorded.

RESULTS

The etiology was identified in 404 (45.6%) of 885 episodes, with the most frequent causes being Streptococcus pneumoniae (14%), Mycoplasma pneumoniae (9%), and respiratory viruses (15%; influenza, picornavirus, respiratory syncytial virus, parainfluenza virus, and adenovirus). Antibiotic-resistant pathogens were rare: only 5.4% of patients had an infection for which therapy with penicillin plus doxycycline would potentially fail. Concordance with local antibiotic recommendations was high (82.4%), with the most commonly prescribed regimens being a penicillin plus either doxycycline or a macrolide (55.8%) or ceftriaxone plus either doxycycline or a macrolide (36.8%). The 30-day mortality rate was 5.6% (50 of 885 episodes), and mechanical ventilation or vasopressor support were required in 94 episodes (10.6%). Outcomes were not compromised by receipt of narrower-spectrum beta-lactams, and they did not differ on the basis of whether a pathogen was identified.

CONCLUSIONS

The vast majority of patients with CAP can be treated successfully with narrow-spectrum beta-lactam treatment, such as penicillin combined with doxycycline or a macrolide. Greater use of such therapy could potentially reduce the emergence of antibiotic resistance among common bacterial pathogens.

Prevalence of antimicrobial resistance in Enterococcus isolates in Australia, 2005: report from the Australian Group on Antimicrobial Resistance

Antibiotic resistance in Enterococcus species causing clinical disease was examined in a point-prevalence study in 2005. Twenty-two sites around Australia collected up to 100 consecutive isolates and tested them for susceptibility to ampicillin, vancomycin, high-level gentamicin and/or high-level streptomycin using standardised methods. Results were compared to similar surveys conducted in 1995, 1999 and 2003. In the 2005 survey, Enterococcus faecalis (1,987 strains) and E. faecium (180 strains) made up 98.6% of the 2,197 isolates tested. Ampicillin resistance was common (77%) in E. faecium, but rare still in E. faecalis (0.2%). Resistance to vancomycin was 7.2% in E. faecium and 0.2% in E. faecalis; the vanB gene was detected in all vancomycin-resistant isolates. High-level resistance to gentamicin was 35.8% in E. faecalis and 52.2% in E. faecium; the figures for high-level streptomycin resistance were 10.3% and 60.2% respectively. Compared to previous Australian Group on Antimicrobial Resistance surveys in 1995, 1999 and 2003, the proportions of vancomycin resistance and high-level gentamicin resistance in enterococci are increasing. It is important to have an understanding of the occurrence of vancomycin resistant enterococci and high level aminoglycoside resistance in Australia to guide infection control practices, antibiotic prescribing policies and drug regulatory decisions.

Prevalence of MRSA among Staphylococcus aureus isolated from hospital inpatients, 2005: report from the Australian Group for Antimicrobial Resistance

The Australian Group for Antimicrobial Resistance conducted a survey of the prevalence of antimicrobial resistance in unique clinical isolates of Staphylococcus aureus from patients admitted to hospital for more than 48 hours. Thirty-two laboratories from all states and territories collected 2,908 isolates from 1 May 2005, of which 31.9% were methicillin-resistant Staphylococcus aureus (MRSA). The regional prevalence of MRSA varied significantly (P < 0.0001) from 22.5% in Western Australia to 43.4% in New South Wales/Australian Capital Territory. Prevalence of MRSA from individual laboratories varied even more from 4% to 58%. This variation was explained in part by distribution of age with the risk of MRSA significantly (P < 0.0001) increasing with age. Other unmeasured factors including hospital activity and infection control practices in the individual institution may have also contributed. Further investigation is warranted as reductions in prevalence would reduce morbidity, mortality and healthcare costs.

Controlling a multicenter outbreak involving the New York/Japan methicillin-resistant Staphylococcus aureus clone

OBJECTIVE

To describe the control of an outbreak of infection and colonization with the New York/Japan methicillin-resistant Staphylococcus aureus (MRSA) clone in multiple healthcare facilities, and to demonstrate the importance of making an MRSA management policy involving molecular typing of MRSA into a statewide public health responsibility.

SETTING

A range of healthcare facilities, including 2 metropolitan teaching hospitals and a regional hospital, as well as several community hospitals and long-term care facilities in a nonmetropolitan healthcare region.

INTERVENTIONS

A comprehensive, statewide MRSA epidemiological investigation and management policy.

RESULTS

In May 2005, there were 3 isolates referred to the Western Australian Gram-Positive Bacteria Typing and Research Unit that were identified as the New York/Japan MRSA clone, a pandemic MRSA clone with the ability to spread and replace existing clones in a region. Subsequent investigation identified 28 additional cases of infection and/or colonization dating from 2002 onward, including 1 involving a colonized healthcare worker (HCW) who had previously been hospitalized overseas. Of the 31 isolates detected, 25 were linked epidemiologically and via molecular typing to the isolate recovered from the colonized HCW. Four isolates appeared to have been introduced separately from overseas. Although the isolate from the single remaining case patient was genetically indistinct from the isolates that spread within Western Australia, no specific epidemiological link could be established. The application of standard outbreak management strategies reduced further spread.

CONCLUSIONS

The elimination of the New/York Japan MRSA clone in a healthcare region demonstrates the importance of incorporating MRSA management policy into statewide public health programs. The mainstays of such programs should include a comprehensive and effective outbreak identification and management policy (including pre-employment screening of HCWs, where applicable) and MRSA clone identification by multilocus sequence typing.

Multiple vascular anomalies in a regurgitating German shepherd puppy

Five cardio-thoracic vascular anomalies were detected in a German shepherd puppy. The patent ductus arteriosus (PDA) was detected on physical examination (5/6 continuous murmur) and confirmed by echocardiogram. The persistent right aortic arch (PRAA) was suspected by the signalment and history of the patient, and confirmed by survey thoracic radiographs (leftward deviation of the trachea cranial to the heart on the ventrodorsal projection). The ventrally deviated trachea cranial to the heart on the right lateral thoracic radiograph was suggestive of a persistent retroesophageal left subclavian artery and confirmed at surgery. The persistent left cranial vena cava and the left azygous vein were detected at surgery. This case report gives a thorough description of the clinical signs, diagnostics and treatments required for the detection and successful resolution of PRAA. The report describes the importance of having experienced surgeons who can recognize vascular anomalies associated with PRAA in order to successfully alleviate the arch and the coinciding oesophageal stricture without compromising vital blood supplies.

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.

Methicillin-resistant Staphylococcus aureus clones, Western Australia

The emergence of multiple multidrug-resistant Panton-Valentine leukocidin–positive MRSA clones in the community is a major public health concern.

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) was first reported in Western Australia in the early 1990s from indigenous peoples living in remote areas. Although a statewide policy of screening all hospital patients and staff who have lived outside the state for MRSA has prevented the establishment of multidrug-resistant epidemic MRSA, the policy has not prevented SCCmec type IV and type V MRSA clones from becoming established. Of the 4,099 MRSA isolates analyzed (referred to the Gram-positive Bacteria Typing and Research Unit) from July 2003 to December 2004, 77.5% were community-associated MRSA (CA-MRSA). Using multilocus sequence/staphylococcal chromosome cassette mec typing, 22 CA-MRSA clones were characterized. Of these isolates, 55.5% were resistant to >1 non–β-lactam antimicrobial drug. Five Panton-Valentine leukocidin (PVL)–positive CA-MRSA clones were identified. The emergence of multidrug-resistant CA-MRSA clones and the detection of PVL toxin genes in clones previously reported as PVL negative is a major public health concern.

Type V staphylococcal cassette chromosome mec in community staphylococci from Australia

Twenty Australian community staphylococci harboring the type V staphylococcal cassette chromosome mec (SCCmec) were found to belong to eight multilocus sequence types. Five were previously unreported novel type V SCCmec elements. The mec complexes were of two types, based on the polymorphisms in the IS431 transposase genes. Five isolates were multiresistant.

Rapid identification of fungal pathogens in BacT/ALERT, BACTEC, and BBL MGIT media using polymerase chain reaction and DNA sequencing of the internal transcribed spacer regions

We report a direct polymerase chain reaction/sequence (d-PCRS)-based method for the rapid identification of clinically significant fungi from 5 different types of commercial broth enrichment media inoculated with clinical specimens. Media including BacT/ALERT FA (BioMérieux, Marcy l'Etoile, France) (n = 87), BACTEC Plus Aerobic/F (Becton Dickinson, Microbiology Systems, Sparks, MD) (n = 16), BACTEC Peds Plus/F (Becton Dickinson) (n = 15), BACTEC Lytic/10 Anaerobic/F (Becton Dickinson) (n = 11) bottles, and BBL MGIT (Becton Dickinson) (n = 11) were inoculated with specimens from 138 patients. A universal DNA extraction method was used combining a novel pretreatment step to remove PCR inhibitors with a column-based DNA extraction kit. Target sequences in the noncoding internal transcribed spacer regions of the rRNA gene were amplified by PCR and sequenced using a rapid (24 h) automated capillary electrophoresis system. Using sequence alignment software, fungi were identified by sequence similarity with sequences derived from isolates identified by upper-level reference laboratories or isolates defined as ex-type strains. We identified Candida albicans (n = 14), Candida parapsilosis (n = 8), Candida glabrata (n = 7), Candida krusei (n = 2), Scedosporium prolificans (n = 4), and 1 each of Candida orthopsilosis, Candida dubliniensis, Candida kefyr, Candida tropicalis, Candida guilliermondii, Saccharomyces cerevisiae, Cryptococcus neoformans, Aspergillus fumigatus, Histoplasma capsulatum, and Malassezia pachydermatis by d-PCRS analysis. All d-PCRS identifications from positive broths were in agreement with the final species identification of the isolates grown from subculture. Earlier identification of fungi using d-PCRS may facilitate prompt and more appropriate antifungal therapy.

Antimicrobial activities of garenoxacin (BMS 284756) against Asia-Pacific region clinical isolates from the SENTRY program, 1999 to 2001

Between 1999 and 2001, 16,731 isolates from the Asia-Pacific Region were tested in the SENTRY Program for susceptibility to six fluoroquinolones including garenoxacin. Garenoxacin was four- to eightfold less active against Enterobacteriaceae than ciprofloxacin, although both drugs inhibited similar percentages at 1 microg/ml. Garenoxacin was more active against gram-positive species than all other fluoroquinolones except gemifloxacin. For Staphylococcus aureus, oxacillin resistance was high in many participating countries (Japan, 67%; Taiwan, 60%; Hong Kong, 55%; Singapore, 52%), with corresponding high levels of ciprofloxacin resistance (57 to 99%) in oxacillin-resistant S. aureus (ORSA). Of the ciprofloxacin-resistant ORSA isolates, the garenoxacin MIC was >4 microg/ml for only 9% of them. For Streptococcus pneumoniae, penicillin nonsusceptibility and macrolide resistance were high in many countries. No relationship was seen between penicillin and garenoxacin susceptibility, with all isolates being susceptible at <2 microg/ml. There was, however, a partial correlation between ciprofloxacin and garenoxacin MICs. For ciprofloxacin-resistant isolates for which garenoxacin MICs were 0.25 to 1 microg/liter, mutations in both the ParC and GyrA regions of the quinolone resistance-determining region could be demonstrated. No mutations conferring high-level resistance were detected. Garenoxacin shows useful activity against a wide range of organisms from the Asia-Pacific region. In particular, it has good activity against S. aureus and S. pneumoniae, although there is evidence that low-level resistance is present in those organisms with ciprofloxacin resistance.

Screening and electronic labelling of ward contacts of vancomycin-resistant Enterococcus faecium vanB carriers during a single-strain hospital outbreak and after discharge from hospital

A large single-strain outbreak of vancomycin-resistant Enterococcus faecium (VREF) vanB occurred in Royal Perth Hospital from July to December 2001. When a VREF-carrying patient was discovered on a ward, all patients on the ward were screened with rectal swabs. A total of 172 patients were colonised, four with infections, but no deaths were attributable to VREF. The number of rectal swabs required to detect each carrier was recorded. On average four rectal swabs, each collected on separate days, were needed to detect more than 90 per cent of the 172 VREF carriers who were epidemiologically linked to the Royal Perth Hospital outbreak. An electronic alert system (Micro-Alert) was used to identify ward contacts of VREF carriers and enabled those who had not been screened before discharge to be followed-up and screened. Ninety-six contacts were actively followed-up in October 2001 and 32 (33.3%) were found to be VREF carriers. From 28 September 2001 to 30 April 2002, a total of 1,977 ward contacts were screened after discharge from hospital and 54 (2.73%) were found to be carrying VREF. We conclude that during single-strain outbreaks of vancomycin-resistant enterococci in hospitals, patient contacts need to be screened on more than three occasions in order to detect most of the carriers and control the outbreak. Secondly, electronic labelling and active follow-up of ward contacts of VREF carriers resulted in a significant number of carriers being detected who otherwise posed a risk of initiating further outbreaks in hospitals if they were readmitted.

Rapid detection of vanA and vanB genes directly from clinical specimens and enrichment broths by real-time multiplex PCR assay

A real-time PCR assay previously developed for use on the Roche LightCycler platform was investigated as an alternative to culture for the direct detection of vancomycin-resistant enterococci (VRE) in clinical specimens. PCR primers and fluorescence resonance energy transfer hybridization probes specific for the vanA and vanB genes were combined in a multiplex real-time PCR assay performed directly with fecal material obtained by rectal swabbing and with enrichment broth samples. DNA was prepared from the rectal swabs and enrichment broths with a commercially available DNA preparation column designed specifically for use with fecal specimens. One hundred eighty duplicate rectal swabs were obtained from 42 patients who were previously found to be positive for VRE and who were being monitored for carriage of VRE. Direct and enrichment broth cultures were performed with one swab, while PCR was performed with the other swab as well as any corresponding presumptive positive enrichment broth. In total, 100 specimens from 30 patients remained positive for VRE by at least one method. The multiplex real-time PCR was positive for 88 enrichment broths of rectal swabs from 27 patients but for only 45 rectal swabs from 15 patients. Direct culture was positive for VRE for only 43 specimens from 11 patients, while enrichment broth culture was positive for VRE for 75 specimens from 22 patients. Inhibition studies for the multiplex real-time PCR assay, performed by spiking the DNA extracts from 50 negative rectal swabs and the corresponding enrichment broths with between 1 and 10 CFU of a VanB Enterococcus faecium strain, detected inhibition rates of 55.1 and 10%, respectively. PCR performed directly with enrichment broths was found to be significantly more sensitive than enrichment broth culture (P < 0.025). Negative samples were identified significantly earlier by PCR than by culture alone.

Duration of antimicrobial prophylaxis in vascular surgery

BACKGROUND

This randomized clinical trial compares the incidence of wound infection after vascular surgery in patients who received prophylaxis using the same antibiotic as either a single-dose or a multiple-dose regimen (until the lines/drain tubes were removed, but not for more than 5 days).

METHODS

Each of the 302 patients who entered the study received ticarcillin 3.0 g/clavulanate 0.1 g (Timentin) intravenously immediately after the induction of anesthesia. Patients randomized to the multiple-dose group received an average of 14.3 doses (range 9 to 20).

RESULTS

The incidence of wound infections was 18% (28 of 153) for patients in the single-dose group and 10% (15 of 149) for patients in the multiple-dose group (P = 0.04; relative risk estimate = 2.00, 95% confidence interval = -1.02 to 3.92).

CONCLUSIONS

A multiple-dose antibiotic regimen, rather than single-dose therapy, provides optimal prophylaxis against wound infection for patients undergoing vascular surgery.

Antibiotic prophylaxis for patients undergoing transurethral resection of the prostate

OBJECTIVES

To evaluate the prevention of urinary tract infections (UTIs) after transurethral resection of the prostate (TURP) in a prospective randomized study using a quinolone antibiotic (fleroxacin) to compare the efficacy of: (1) a single oral dose, (2) a single intravenous (IV) dose, and (3) an extended regimen consisting of an initial IV dose followed by oral therapy until removal of the urinary catheter, but for less than 6 days.

METHODS

We excluded from study patients who received antimicrobial agents within 48 hours of surgery. Single-dose prophylaxis consisted of 400 mg of fleroxacin given either orally or intravenously. The extended regimen consisted of an initial 400 mg IV dose followed by 400 mg oral each day (patients older than 75 years, or with a creatinine clearance less than 40 mL/min, received 200 mg/day). UTI was defined as clinical evidence of infection plus the presence of more than 10 white blood cells (WBC)/mm3 in any urine specimen plus the presence of more than 10(4) cfu/mL in midstream urine specimens or more than 10(2) cfu/mL in catheter specimens.

RESULTS

Prior to TURP, 30% (25/84) of the patients had a urethral catheter in situ and 12% (3/25) of these patients had bacteriuria. Only 1 patient developed a UTI and that was 22 days after a TURP (intergroup comparisons, Fisher's exact test greater than 0.05). There were no instances of urosepsis.

CONCLUSIONS

A single oral dose of a fluoroquinolone agent provided optimum prophylaxis for patients undergoing TURP.

The effect of minimum luminal nutrition on bacterial translocation and atrophy of the jejunum during parenteral nutrition

In situations of catabolic stress, the gut becomes atrophic and may have diminished barrier function as evidenced by an increase in bacterial translocation. The aim of this study was to examine the effect of minimum luminal nutrition during parenteral nutrition on the extent of jejunal atrophy and rate of bacterial translocation. Central venous lines were inserted into 30 rats before they underwent randomization to receive nutritional support with: (a) conventional parenteral nutrition; (b) conventional parenteral nutrition with 3 g/day of rat food (i.e., minimum luminal nutrition); or (c) rat food ad libitum. The rats were assessed after 10 days for nutritional status, extent of jejunal atrophy, caecal flora, as well as the extent of bacterial translocation to the mesenteric lymph nodes, liver and spleen. Rats in the rat food ad libitum group lost the smallest amount of weight and had the least amount of jejunal atrophy, yet had a similar rate of bacterial translocation as the parenterally nourished groups. When compared with the conventional parenteral nutrition group, the minimum luminal nutrition group had better preservation of the weight of the small bowel and its isolated mucosa (P < 0.01), but had a similar rate of bacterial translocation. Minimum luminal nutrition reduced the extent of atrophy of the gut but did not affect the incidence of bacterial translocation. It is inferred that there is no direct relationship between the extent of mucosal atrophy and incidence of bacterial translocation.

A blinded comparison of two methods of viral susceptibility testing: plaque reduction assay versus microplate in situ ELISA

Viral susceptibility testing has been shown to have a role in the management of patients with herpes simplex infections. In this study, 25 isolates of herpes simplex virus representing a broad spectrum of acyclovir-susceptible and -resistant phenotypes were tested using a microplate in situ enzyme-linked immunosorbent assay (MISE). This method is objective and more rapid than the traditional plaque reduction assay (PRA). The previously derived PRA results were not known at the time of testing with the MISE method. The correlation coefficient between PRA and MISE was 0.85. Agreement on sensitive or resistant was reached for 21 of 25 isolates. The standardised microplate in situ ELISA was found to be an acceptable alternative to the plaque reduction assay.

Standardisation of a microplate in situ ELISA (MISE-test) for the susceptibility testing of herpes simplex virus to acyclovir

Viral susceptibility testing has been traditionally performed by plaque reduction assay (PRA) which is labour intensive, time consuming and requires subjective input by the reader. An in situ enzyme-linked immunosorbent assay (ELISA) method has been developed with the potential to overcome many of the limitations of PRA, and has been applied to a variety of viruses. Previous reports of ELISA susceptibility assays have shown little standardisation between these methods, or any significant analysis of the variable factors which may influence the outcome of the assay. This study optimised the sensitivity of a microplate in situ ELISA (MISE-test) for the detection of viral growth, manipulated the interaction between cells, virus and acyclovir to determine the effect of their relationship on susceptibility results, and established standard assay conditions based on quality controlled parameters such as assay variability and linear ranges. 33 isolates of HSV-2 were tested for susceptibility to acyclovir by PRA, and the standardised MISE. Factors which were critical to the performance of the MISE included inoculum size, inoculation method, duration of incubation, fixative type, immunoglobulin working strengths and choice of chromogenic substrate. Using the ELISA it was possible to separate sensitive HSV-2 isolates from resistant isolates applying a cutoff ID50 value of 2.0 mg/l. The correlation coefficient between PRA and MISE was 0.65. The standardised microplate in situ ELISA was found to be an acceptable alternative to the plaque reduction assay.

Duodenal ulcer treated with Helicobacter pylori eradication: seven-year follow-up

The long-term benefits of Helicobacter pylori-eradication treatment (HET) in H pylori-associated duodenal ulcer are unclear. We followed up patients with duodenal ulcers from a trial of H pylori eradication in 1985-86. 63 of 78 patients (81%) were reviewed clinically and had upper gastrointestinal endoscopy with gastric antral biopsy. Of 35 patients previously rendered H pylori negative, 32 (92%) remained H pylori negative after 7.1 years (mean). All patients initially H pylori positive remained infected, unless HET was given in the interim. Duodenal ulceration was found in 20% (5 out of 25) of patients remaining H pylori-positive, compared with 3% (1 of 38) of H pylori-negative patients (p < 0.05). The reduction of duodenal ulcer relapse obtained from H pylori eradication in H pylori-associated duodenal ulcer extends to at least 7 years after treatment, and is likely to be due to freedom from H pylori infection. However, duodenal ulcer may recur in patients rendered H pylori negative, due to factors other than reinfection with H pylori.

When is Helicobacter pylori infection acquired?

Cross sectional surveys have shown an increasing prevalence of Helicobacter pylori (H pylori) infection with increasing age in Western populations. The aim of this study was to examine the pattern of acquisition of H pylori infection over a 21 year period in a group of 141 adults who had blood samples and serum stored in 1969, 1978, and 1990. A prevalence of H pylori antibody of 39% in 1969 serum samples, 40.9% in 1978, and 34.8% in 1990 was found when assessed by an enzyme linked immunosorbent assay (ELISA). Of the 86 subjects who were seronegative in 1969, only six (7%) were seropositive in 1990. These data suggest that a cohort effect may contribute to the pattern of increasing prevalence of H pylori infection seen with increasing age. Acquisition of infection in adults is rare. It is unlikely, therefore, that reinfection will occur after successful eradication.

Distribution and activity of amphotericin B in humans

Concentrations of amphotericin B (AmB) in tissues obtained at autopsy from eight patients were measured by high-performance liquid chromatography (HPLC). The patients had received doses of 101-2,688 mg of antibiotic. Highest concentrations of the drug were found in the liver; in one patient the amount of AmB in the liver was 41% of the total dose. No evidence of metabolism of the drug was observed, and bioassay of ethanol extracts of tissue showed that the drug retained activity. Three of the patients had histologic evidence of aspergillar or candidal infection in tissues with concentrations of AmB ranging from 2.5 to 166 micrograms/g. With two patients, the concentrations of the drug in the tissues exceeded by greater than or equal to 10-fold the minimum inhibitory concentrations of the drug in isolates that had been obtained from the same tissues. Unknown factors present in tissues appear to limit the in vivo activity of AmB.

Control of methicillin-resistant Staphylococcus aureus (MRSA) in an Australian metropolitan teaching hospital complex

In April 1982, a patient infected with methicillin-resistant Staphylococcus aureus (MRSA) was transferred to the Royal Perth Hospital from the Royal Darwin Hospital. Within three months, 19 patients and four staff members had become infected or colonized with MRSA. The outbreak was terminated only after all colonized inpatients were transferred to a separate isolation unit. After the outbreak, all new patients and new employees who had been in hospitals outside Western Australia in the previous 12 months were screened. From June 1, 1982, to June 30, 1984, 28 of the 649 patients (4.3%) screened on admission to the Royal Perth Hospital were found to be harbouring MRSA. During the same period only one of the 468 persons (0.2%) screened on application for employment at the Hospital was found to be colonized with MRSA. Since the policy of screening new patients and staff from hospitals outside Western Australia was introduced, no serious outbreak of MRSA has occurred.

Rate of arabinitol production by pathogenic yeast species

D-Arabinitol is a five-carbon polyol that is produced by many fungi. Detection of the metabolite has been reported in serum from patients with invasive candidiasis. We studied the production and assimilation of arabinitol by 46 clinical isolates of yeast species. Cultures of isolates of Candida albicans (9 strains), Candida tropicalis (12 strains), Candida parapsilosis (13 strains), Candida krusei (4 strains), Candida pseudotropicalis (3 strains), Torulopsis glabrata (3 strains), and Cryptococcus neoformans (2 strains) were assayed by gas-liquid chromatography. Yeast cells were cultured at 34 degrees C in yeast nitrogen base with 3.0 g of glucose per liter. At 1.5- to 3-h intervals, cells were counted and glucose and arabinitol were measured in media filtrates. The levels of arabinitol in cultures with 7.5 X 10(6) yeast cells per ml were compared. The mean concentrations of the metabolite in C. albicans, C. tropicalis, C. parapsilosis, and C. pseudotropicalis cultures wee 14.1, 1.6, 8.4, and 5.5 micrograms/ml, respectively. No arabinitol was detected in cultures of C. krusei, T. glabrata, or C. neoformans.