Isolated Neurogenic Bladder Associated With Human T-Lymphotropic Virus Type 1 Infection in a Renal Transplant Patient From Central Australia: A Case Report.

BACKGROUND: Human T-lymphotropic virus type 1 (HTLV-1) is endemic amongst the Aborigines of the Northern Territory of Australia. HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been associated with this infection. In general population, isolated neurogenic bladder dysfunction in HTLV-1-infected individuals without HAM/TSP has been reported, and the HTLV-1 proviral load has been found to be higher in such patients compared with asymptomatic carriers. In solid organ transplantation, few cases of HAM/TSP have been reported worldwide, but not an isolated neurogenic bladder. CASE: A 50-year-old indigenous women from Alice Springs with end stage renal disease secondary to diabetic nephropathy with no prior history of bladder dysfunction received a cadaveric renal allograft following which she developed recurrent urinary tract infections. The recipient was seropositive for HTLV-1 infection. HTLV-1 status of donor was not checked. Urodynamic studies revealed stress incontinence and detrusor overactivity without urethral intrinsic sphincter deficiency. She had no features of myelopathy. There was elevation of the serum and cerebrospinal fluid HTLV-1 proviral load. The magnetic resonance imaging myelogram was normal. Pyelonephritis was diagnosed based on clinical features, positive cultures, and renal allograft biopsy. Continuous suprapubic catheter drainage helped preventing further episodes of allograft pyelonephritis in spite of chronic colonization of the urinary tract. CONCLUSION: Isolated bladder dysfunction is a rare manifestation of HTLV-1 infection and is probably associated with high proviral loads. This may adversely affect renal allograft and patient outcomes.

The Epidemiology of Staphylococcus aureus and Panton-Valentine Leucocidin (pvl) in Central Australia, 2006-2010.

BACKGROUND: The Central Australian Indigenous population has a high incidence of Staphylococcus aureus bacteremia (SAB) but little is known about the local molecular epidemiology. METHODS: Prospective observational study of bacteremic and nasal colonizing S.aureus isolates between June 2006 to June 2010. All isolates underwent single nucleotide polymorphism (SNP) genotyping and testing for the presence of the Panton-Valentine Leucocidin (pvl) gene. RESULTS: Invasive isolates (n = 97) were predominantly ST93 (26.6 %) and pvl positive (54.3 %), which was associated with skin and soft tissue infections (OR 4.35, 95 % CI 1.16, 16.31). Non-multiresistant MRSA accounted for 31.9 % of bacteremic samples and showed a trend to being healthcare associated (OR 2.16, 95 % CI 0.86, 5.40). Non-invasive isolates (n = 54) were rarely ST93 (1.9 %) or pvl positive (7.4 %). CONCLUSIONS: In Central Australia, ST93 was the dominant S.aureus clone, and was frequently pvl positive and associated with an aggressive clinical phenotype. Whether non-nasal carriage is more important with invasive clones or whether colonization occurs only transiently remains to be elucidated.

Staphylococcus aureus bacteraemia at Alice Springs Hospital, Central Australia, 2003-2006.

BACKGROUND: Infectious diseases remain the leading cause of death at Alice Springs Hospital (ASH) and Staphylococcus aureus bacteraemia (SAB) is the second most common bloodstream infection. Non-multidrug-resistant, methicillin-resistant S. aureus (nmMRSA) is endemic to the region. AIMS: To determine whether differences exist between racial groups and resistance phenotypes in the clinical manifestations and outcomes of SAB at ASH. METHODS: A retrospective review of medical and pathology records for inpatients with SAB between 1 January 2003 and 31 December 2006. RESULTS: A total of 125 patients (indigenous, 111; non-indigenous, 14) presented with SAB during the study period. Among indigenous patients, there were 95 adults and 16 children. No non-indigenous child was admitted with SAB. The mean annual incidence rate was 160.7/100 000 indigenous population and 8.1/100 000 non-indigenous population (incidence rate ratio 19.9) (P = 0.010). Isolates were predominantly methicillin-susceptible S. aureus (indigenous, 85; non-indigenous, 13). Twenty of 27 MRSA isolates were non-multidrug-resistant. Indigenous adults were more likely to present with an infective focus (indigenous, 75; non-indigenous, 6) (P = 0.004). These were most often skin infections (skin abscesses, 31; scabies, 4). Twenty-seven indigenous adults self-discharged after receiving a median of only 5 days (inter-quartile range (IQR), 3-9) of antibiotic therapy. Ninety-day mortality rates for indigenous and non-indigenous adults were 14.7% and 14.3% respectively. The median age of death for indigenous adults was 50 years (IQR, 37-68). CONCLUSIONS: Indigenous Australians have the highest reported incidence rate of SAB worldwide. This reflects the socioeconomic disadvantage experienced by indigenous Australians whose living conditions predispose to pathogen transmission and limits opportunities to maintain adequate skin hygiene.

Strongyloides stercoralis: a cause of morbidity and mortality for indigenous people in Central Australia.

BACKGROUND: Strongyloides stercoralis may cause a complicated infection in immunocompromised patients, which has a high case fatality rate. Death generally results from sepsis with enteric pathogens. Globally, infection with the human T-cell lymphotropic virus type 1 (HTLV-1) is a major risk factor for this syndrome. Both S. stercoralis and HTLV-1 are endemic to Central Australia. AIMS: The aim of the study was to determine whether complicated strongyloidiasis occurs in association with HTLV-1 infection in Central Australia. METHODS: A retrospective audit of all cases of complicated strongyloidiasis presenting to Alice Springs Hospital between January 2000 and December 2006 was carried out. Diagnosis was defined as definite or probable according to whether diagnosis was made by faecal studies or serology respectively. The medical records, investigations and outcomes of patients who met predetermined criteria for a diagnosis of complicated strongyloidiasis were reviewed. RESULTS: Eighteen indigenous patients met the criteria for complicated strongyloidiasis (definite 9, probable 9). Seven of 11 patients tested were HTLV-1 seropositive. At diagnosis, no treatment was documented for nine patients (definite 4, probable 5), three received a single dose of ivermectin and one a single dose of albendazole. Fifteen patients (83%) died because of sepsis (definite 7, probable 8). Pathogens isolated and their foci of infection included Klebsiella pneumoniae pneumonia (4), bloodstream infection with Enterococcus spp. (2), K. pneumoniae peritonitis (1) and streptococcal meningitis (1). CONCLUSION: Complicated strongyloidiasis occurs in association with HTLV-1 infection in central Australia. This finding has significant implications for the management of S. stercoralis in the region.

Strongyloides stercoralis: risks posed to immigrant patients in an Australian tertiary referral centre.

BACKGROUND: Strongyloides stercoralis is a nematode human parasite with a global prevalence that is able to maintain a prolonged infestation by means of its autoinfective life cycle. Immunosuppression may result in a life-threatening hyperinfection syndrome. Recent changes in migration have resulted in the arrival of many immigrants from endemic areas. As to whether physicians are alert to the risks of strongyloidiasis in these patient groups is unclear. The aim of the study was to assess the risks posed by chronic strongyloidiasis in patients presenting to a tertiary referral centre and the need for screening of immigrant patients before immunosuppression. METHODS: The study comprised a retrospective review of cases of strongyloidiasis presenting to the Alfred Hospital, Melbourne. Thirty-three cases were diagnosed by either positive serology or faecal microscopy between January 1998 and January 2005. The medical records for 29 cases were examined with regard to demographics, clinical features and complications. RESULTS: Two major groups were identified: immigrants (17) and returned travellers (11). Six immigrants, but no returned traveller, developed a hyperinfective syndrome. Five immigrants received immunosuppressive therapies before developing symptoms of hyperinfection and this was complicated by life-threatening sepsis in two patients. Diagnosis was frequently delayed in the immigrant group who were significantly more likely to present with respiratory symptoms. Four immigrants and two returned travellers were treated with corticosteroids for symptoms that were probably related to larval migration. CONCLUSION: Before giving immunosuppressive therapies, patients with a history of potential exposure must be investigated for strongyloidiasis and consideration given to empirical treatment.

Activity and motor unit size in partially denervated rat medial gastrocnemius.

The aim of the study was to determine whether increased motoneuron activity induced by treadmill walking would alter the extent of motoneuron sprouting in the partially denervated rat medial gastrocnemius muscle. An extensive partial denervation was effected by unilateral section of the L5 ventral root, and it is very likely that all units remaining in the medial gastrocnemius were used in treadmill walking. Rats were trained for 1.5 h/day and after 14 days were walking at least 1 km/day. Motor unit characteristics were determined 24 days after the partial denervation and were compared with units from partially denervated control (PDC) animals and with units from normal (control) animals. In PDC rats, force developed by slow, fast fatigue-resistant, and fast intermediate-fatigable motor units increased substantially compared with control animals; that of fast-fatigable units did not increase. In partially denervated exercised animals, force developed by slow and fast-fatigue-resistant units showed no further increase, but fast-intermediate- and fast-fatigable units showed significant increases compared with those in PDC animals. The changes in force were closely paralleled by changes in innervation ratios. We concluded that neuronal activity is an important factor in determining the rate of motoneuron sprouting.

Motor units within the normal rat medial gastrocnemius.

The contractile properties, fatiguability and axonal conduction velocity were determined for 118 motor units in the medial gastrocnemius of eighteen rats. Fast-twitch and slow-twitch units could be categorized on the basis of the 'sag' test. For the purposes of statistical comparison the fast-twitch units were classified on the basis of their fatiguability as fast-fatiguable (FF), fast intermediate (FI) and fast fatigue-resistant (FR). As such, FR units tended to have a longer isometric twitch time course than other fast-twitch units. On the basis of peak tetanic force FF units were largest (mean 341 +/- 120 mN) followed by FI (145 +/- 85 mN), FR (87.3 +/- 38) and slow units (40.4 +/- 11.0 mN). There were no differences in motor axonal conduction velocity. Although units were categorized, it is clear that for all characteristics investigated the fast-twitch units exist as a continuum. Some of the largest FF units (peak force 350-500 mN) failed to maintain force with high-frequency stimulation (300 Hz) and this was associated with a failure of the EMG signal.

Alterations in the contractile properties of motor units within the ageing rat medial gastrocnemius.

The decline in muscle force accompanying senescence is associated with a loss of motor nerves which provides some opportunity for collateral reinnervation and alterations in the mechanical properties of surviving motor units. The contribution of the different motor unit types to this neuromuscular reorganization was investigated by determining the isometric contractile properties of single motor units within the medial gastrocnemius of rats aged 791 +/- 39 days. These were compared with a group of similarly isolated and classified units within young adult rats aged between four and five months. The estimated number of units decreased significantly from 93 +/- 28 in young adults to 66 +/- 19 in senescent animals. There was a preferential loss of fast motor units and a significant loss of myelinated axons within the muscle nerve. The maximum tetanic force developed by FF motor units decreased with age while that of the more fatigue resistant FI and FR motor units increased. Other contractile properties were unaltered and there was no change in any contractile parameter for S unit types. Alterations in the cross-sectional areas and proportions of histochemically classified muscle fibres reflected these changes. The proportion of FG fibres declined with age and there was evidence of denervation, particularly within the peripheral rim of fast type fibres. The number of muscle fibres within the medial gastrocnemius decreased with age. These results indicate that fast motor units are most severely affected during the early stages of senescence. Within this population the FF motor units which have the largest innervation ratios in the young adult may suffer preferential degeneration.

Effect of partial denervation on motor units in the ageing rat medial gastrocnemius.

The ageing neuromuscular system is thought to undergo a continual process of reorganization as motoneurones are lost and surviving motor nerves reinnervate neighbouring denervated muscle fibres. However, the extent to which collateral reinnervation is able to compensate for neural deficits in the ageing individual is unknown. The ability of the senescent motoneurone to increase the size of its peripheral field was therefore investigated following transection of the right L5 ventral root in male Sprague Dawley rats aged 775 +/- 50 days. This procedure resulted in an extensive partial denervation of the right medial gastrocnemius muscle. After a recovery period of between 28 and 31 days the isometric contractile properties of surviving motor units were compared to control motor units from both the contralateral muscle and a group of unoperated control animals aged 791 +/- 39 days. Motor unit force was found to be unchanged after partial denervation and the absence of any alteration in motor unit size was confirmed by histological analysis. However, the time course of the isometric twitch was significantly longer for both fast and slow motor unit types and the conduction velocity of motoneurones innervating fast units was decreased following partial denervation. These results demonstrate that senescent motor nerves are unable to substantially increase the size of their peripheral fields by extensive collateral reinnervation.

Sprouting of fusimotor neurones after partial denervation of the cat soleus muscle.

Normally, gamma motoneurones innervate only the intrafusal fibres of muscle spindles. This is a report of sprouting of gamma motoneurones to innervate extrafusal muscle fibres following partial denervation of the soleus muscle of kittens. In eight newborn animals, the L7 ventral root was cut on one side under anaesthesia and the animals were then allowed to recover. At approximately 100 days of age animals were reanaesthetised and a study made of mechanical properties of motor units whose axons ran in the S1 ventral root and supplied the partially denervated soleus muscle. Evidence was obtained for sprouting of all surviving alpha motoneurones. In addition, in four experiments axons conducting within the gamma range, on stimulation, produced measurable tension. In one experiment, stimulation of one such gamma axon also produced specific fusimotor effects on four afferents identified as coming from primary endings of muscle spindles. The gamma axon was therefore a fusimotor axon. The effect observed on stimulation of the gamma axon suggested a largely dynamic action. Other examples of gamma axons were encountered that on stimulation produced tension, but which could not be specifically associated with spindles. In addition, a number of gamma axons that did not develop tension were shown, on stimulation, to have fusimotor effects that were static in action. It is concluded that in extensively denervated muscles gamma motoneurones may sometimes sprout to innervate extrafusal fibres. The mechanical properties of the extrafusal fibres innervated by such gamma axons were similar to those of ordinary alpha motor units.