Long-term outcomes of Murray Valley encephalitis cases in Western Australia: what have we learnt?

BACKGROUND: Murray Valley encephalitis virus (MVEV) is a mosquito-borne flavivirus that causes encephalitis in some cases of infection. It is endemic in Northern Australia and cases occasionally occur in South Eastern Australia. The long-term sequelae of MVEV infection have not previously been well described. AIM: To investigate the long-term sequelae of MVEV infection. METHODS: This was a descriptive case series of all clinical MVEV infections using data linkage and standard surveys. Hospital admissions, emergency department, psychiatric outpatients and mortality data were obtained. We attempted to follow-up all 53 cases of MVEV clinical infection that occurred in Western Australia from 1978 to 2011 inclusive. Two cases opted out of the study. RESULTS: We followed-up 39 surviving cases. Seven of the nine with paralysis or paresis were under 5 years and they fared worse than other patients, requiring lengthy hospitalisation (median duration 133 days). Two died due to complications of quadriplegia following a total of 691 days in hospital. Nine surviving patients, including two with non-encephalitic illness, required care for depression and other psychiatric conditions following MVEV infection. Two patients who were discharged with neurological sequelae had no further documented hospital occasions of service but reported ongoing challenges with cognitive dysfunction and inability to work. CONCLUSIONS: This is the first study of long-term outcomes of Murray Valley encephalitis that included cases with no obvious sequelae at discharge. In spite of the small numbers involved, the study demonstrated the significant medical and social burden due to MVEV in Australia.

Comparison of noninvasive models of fibrosis in chronic hepatitis B.

BACKGROUND AND GOALS: Liver fibrosis influences treatment and surveillance strategies in chronic hepatitis B (CHB). This multicenter study aimed to examine the accuracy of serum fibrosis models in CHB patients including those with low alanine aminotransferase (ALT) levels and serially in those undergoing treatment. METHOD: We examined noninvasive fibrosis models [Hepascore, Fibrotest, APRI, hepatitis e antigen (HBeAg)-positive and -negative models] in 179 CHB patients who underwent liver biopsy and fibrosis assessment by METAVIR and image morphometry. Serial Hepascore measurements were assessed in 40 subjects for up to 8.7 years. RESULTS: Hepascore was more accurate than Fibrotest [area under the curve (AUC) 0.83 vs. 0.72, P = 0.05] and HBeAg-positive model (AUC 0.83 vs. 72, P = 0.03) for significant fibrosis but was not significantly different to APRI or HBeAg-negative scores. Fibrosis area assessed by morphometry was correlated with Hepascore (r = 0.603, P < 0.001), Fibrotest (r = 0.392, P = 0.03), and HBeAg-positive (r = 0.492, P = 0.001) scores only. Among 73 patients with an ALT <60 IU/L, noninvasive models were useful to predict fibrosis (PPV 80-90%) or exclude significant fibrosis (NPV 79-100%). Hepascore increased significantly among patients monitored without treatment and reduced among patients undergoing therapy (0.05/year ± 0.03 vs. -0.04/year ± 0.02, P = 0.007). CONCLUSIONS: Serum fibrosis models are predictive of fibrosis in CHB and assist in identifying subjects with low-normal ALT levels for treatment.

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.

Diagnosis of malaria aided by polymerase chain reaction in two cases with low-level parasitaemia.

Light microscopy of thick and thin blood smears is the mainstay of malaria diagnosis. In situations of low-level parasitaemia such as drug-modified disease, however, this may be difficult making clinical management problematic. Polymerase chain reaction (PCR) methods have shown high sensitivity for the diagnosis of malaria and are able to differentiate the Plasmodium species involved. Two cases are presented in the present study, which illustrate how a PCR method can aid light microscopic malaria diagnosis and species differentiation in returned travellers with low-level parasitaemia. Plasmodium vivax was detected by PCR prior to the light microscopy becoming positive in one case, and in the second case Plasmodium malariae was detected when light microscopy was unable to speciate the causative Plasmodium species.

Evaluation of four methods for rapid identification of Staphylococcus aureus from blood cultures.

The identification of Staphylococcus aureus directly from blood cultures is clinically relevant, but it requires a test that is both rapid and reliable. Previously, biochemical, immunological, tube coagulase, and thermostable-endonuclease methods have shown variable sensitivity and specificity. Testing directly from blood culture broth has not been described for the latex kit Staphaurex Plus (Murex Diagnostics Ltd.), and the modified conventional tests have not been used with the newer, continuously monitored blood culture systems. In addition, the commercial RAPIDEC staph kit (bioMerieux Vitek, Inc.) has been used to detect S. aureus directly from the Vital blood culture system (bioMerieux, Marcy l'Etoile, France), but its performance has not been evaluated with other continuously monitored systems. A total of 201 clinical blood cultures (BACTEC 9240 culture system; Johnston Laboratories, Inc.) in which a Gram stain showed gram-positive cocci resembling staphylococci were evaluated prospectively. The Staphaurex Plus kit, the tube coagulase test, the thermostable-endonuclease test, and the RAPIDEC staph kit were compared. The sensitivities were 23, 92, 85, and 98% and the specificities were 99, 100, 93, and 100%, respectively. The RAPIDEC staph kit was the most reliable test, with a diagnostic accuracy comparable to that of the best published results for any of the rapid tests. However, it was the most expensive of the tests and relatively labor-intensive. The tube coagulase test was also sensitive, the simplest to perform, and inexpensive.

Typing of Neisseria meningitidis by restriction analysis of the amplified porA gene.

We tested a typing system for 54 isolates of Neisseria meningitidis using polymerase chain reaction (PCR) amplification of the porA gene. The isolates were obtained between 1989 and 1994 from cases in Western Australia and Sydney. The PCR product was digested by five restriction endonucleases (AluI, HaeIII, HinfI, RsaI and HpaII) giving a restriction fragment length polymorphism (RFLP) pattern for each isolate. All of the isolates were able to be assigned an RFLP pattern, whereas 24 could be fully serotyped and serosubtyped. The method was rapid and simple to perform and results were easy to interpret. Two outbreaks of invasive meningococcal disease were included in the analysis, one involving an hyperendemic focus of disease and the other characteristic of a point outbreak. The typing system demonstrated the genetic relatedness of isolates from the point outbreak and the genetic diversity among the hyperendemic strains. We conclude that the method is discriminatory and is a useful supplement to serological typing for studying Australian outbreaks of invasive meningococcal disease.

Staphylococcal adherence to chicken cartilage.

Immature chicken cartilage was incubated in a Staphylococcus aureus suspension and then washed. Scanning electron microscopy and radiolabel measurements showed increased adherence to cartilage with increasing bacterial concentration. Preheating of the bacteria did not reduce the adherence property, but trypsin treatment did.

Ultrastructural studies of adherence of Staphylococcus aureus in experimental acute hematogenous osteomyelitis.

A model of acute hematogenous osteomyelitis initiated by injection of Staphylococcus aureus into 29-day-old chickens was used. Transmission electron microscopy showed that the bacteria adhered to exposed cartilage matrix in the metaphyseal region of long bones but not to adjacent vascular linings or to erythrocytes. It is proposed that the combination of exposure of growth plate cartilage during normal bone growth and the ability of S. aureus to adhere to this cartilage is the mechanism for initiation of infection which proceeds to an osteomyelitic abscess.