Raymond Chan

Gentamicin ototoxicity: a 23-year selected case series of 103 patients

Objective: To review patients with severe bilateral vestibular loss associated with gentamicin treatment in hospital.

Human Papillomavirus (HPV) in Atypical Squamous Cervical Cytology: the Invader HPV Test as a New Screening Assay

ABSTRACT In surveillance for cervical neoplasia, a diagnosis of cytologically atypical squamous cells of undetermined significance (ASCUS) presents a significant clinical issue, often dependent on testing for high-risk (HR) human papillomavirus (HPV) for the triage of patients. HPV type 16 now appears to be a critical concern in the follow-up of patients with ASCUS. The Invader HPV (Inv2) test, by Third Wave Technologies, Inc., is a recently developed analyte-specific reagent assay that uses probe sets for the detection of 14 HR HPV subtypes. These probe sets are A5/A6 (HPV types 51, 56, and 66), A7 (HPV types 18, 39, 45, 59, and 68), and A9 (HPV types 16, 31, 33, 35, 52, and 58). This report describes the performance characteristics of the Inv2 test in the screening of ASCUS cervical cytology specimens and correlates the results of the Inv2 test with those of the Hybrid Capture II HPV (HC2) test by Digene. The linear array HPV genotyping test (Roche Molecular Systems) was used as a reference method for the testing of samples with discordant results. Ninety-four Pap smear samples with a cytological diagnosis of ASCUS and 39 samples with a negative diagnosis were tested. The results of the Inv2 test demonstrated a good (86.6%) concordance with those of the HC2 test, with an overall sensitivity and specificity of 96% for the Inv2 test. Additionally, the Inv2 assay, which offers high-throughput, semiautomated DNA extraction, allows the subgrouping of HPV types by differential probe sets, could provide a useful test for screening for HPV, and has the potential to provide an improved means of risk stratification and the selection of patients for further HPV subtyping.

Neuro-ophthalmology of invasive fungal sinusitis: 14 consecutive patients and a review of the literature

Invasive fungal sinusitis is a rare condition that usually occurs in immunocompromised patients and often presents as an orbital apex syndrome. It is frequently misdiagnosed on presentation and is almost always lethal without early treatment.

Whole Genome Sequencing in Real-Time Investigation and Management of a Pseudomonas aeruginosa Outbreak on a Neonatal Intensive Care Unit.

OBJECTIVE To use whole genome sequencing to describe the likely origin of an outbreak of Pseudomonas aeruginosa in a neonatal unit. DESIGN Outbreak investigation. SETTING The neonatal intensive care unit service of a major obstetric tertiary referral center. PATIENTS Infants admitted to the neonatal unit who developed P. aeruginosa colonization or infection. METHODS We undertook whole genome sequencing of P. aeruginosa strains isolated from colonized infants and from the neonatal unit environment. RESULTS Eighteen infants were colonized with P. aeruginosa. Isolates from 12 infants and 7 environmental samples were sequenced. All but one of the clinical isolates clustered in ST253 and no differences were detected between unmapped reads. The environmental isolates revealed a variety of sequence types, indicating a large diverse bioburden within the unit, which was subsequently confirmed via enterobacterial repetitive intergenic consensus-polymerase chain reaction typing of post-outbreak isolates. One environmental isolate, obtained from a sink in the unit, clustered within ST253 and differed from the outbreak strain by 9 single-nucleotide polymorphisms only. This information allowed us to focus infection control activities on this sink. CONCLUSIONS Whole genome sequencing can provide detailed information in a clinically relevant time frame to aid management of outbreaks in critical patient management areas. The superior discriminatory power of this method makes it a powerful tool in infection control.

Healthcare workers and immunity to infectious diseases.

Objective: In 2002, New South Wales (NSW) Health introduced an updated policy for occupational screening and vaccination against infectious diseases. This study describes healthcare worker (HCW) immunity to hepatitis B, measles, mumps, rubella (MMR) and varicella based on serological screening, following introduction of this policy.

Patient perceptions of osteomyelitis, septic arthritis and prosthetic joint infection: the psychological influence of methicillin‐resistant Staphylococcus aureus

Introduction: Patients form their own representations of their illness, which can be important determinants of their coping and influence outcome. Our aims were to (i) assess patient perceptions of osteomyelitis, septic arthritis and prosthetic joint infection, (ii) compare perceptions of methicillin‐resistant Staphylococcus aureus(MRSA) with non‐MRSA infection and (iii) investigate the emotional aspects of these infections.

Mesiotemporal changes on magnetic resonance imaging in neurosyphilis.

We report a case of neurosyphilis with magnetic resonance imaging (MRI) brain scan findings compatible with a diagnosis of herpes simplex encephalitis with negative testing for herpes simplex virus in the cerebral spinal fluid. An extensive review of the literature has been undertaken revealing 24 cases worldwide where there are mesiotemporal changes on MRI concurrent with a diagnosis of neurosyphilis. Therefore, it is now well established that neurosyphilis, ‘the great imitator’, should be considered in the differential diagnosis in all patients demonstrating mesiotemporal changes on MRI, changes usually seen in herpes simplex encephalitis.

Desulfovibrio fairfieldensis Bacteremia Associated with Choledocholithiasis and Endoscopic Retrograde Cholangiopancreatography

ABSTRACT Desulfovibrio fairfieldensis is a gram-negative, curved, motile, anaerobic bacillus. D. fairfieldensis has been isolated only from human specimens and is considered a normal resident of the human gastrointestinal tract. We report the second case of Desulfovibrio bacteremia associated with choledocholithiasis and review the other reported cases of D. fairfieldensis bacteremia.

First Australian description of Eggerthella lenta bacteraemia identified by 16S rRNA gene sequencing

Sir, We wish to report the first Australian case of a patient with Eggerthella lenta infection, demonstrating the usefulness of 16S rRNA gene sequencing technology in a clinical diagnostic microbiology laboratory. A 68-year-old woman was admitted to hospital with a two-day history of malaise, anorexia, nausea and colicky abdominal pain. She had no fever or sweats, no change in bowel habit, no diarrhoea or vomiting and no melaena. She had a history of thyroidectomy, ectopic pregnancy and hypertension. On examination, the temperature was 37.48C, the blood pressure 98/58 mmHg and the pulse rate 86 beats per minute. She had generalised abdominal tenderness, but the rest of the examination was unremarkable. Initial radiological investigations showed no pneumoperitoneum, air-fluid levels or distended loops in the bowel. Ultrasound suggested the presence of free fluid in Morrison’s pouch. At laparotomy, purulent peritoneal fluid was seen and foulsmelling pus found around the uterus. The rest of the abdominal organs were macroscopically normal. There was evidence of previous appendicectomy. The patient underwent total abdominal hysterectomy, left salpingo-oophorectomy and irrigation of the peritoneum. The provisional diagnosis was a tubo-ovarian abscess. Intravenous ampicillin, gentamicin and metronidazole were commenced. Gram positive bacilli were isolated in pure growth from the blood cultures performed on admission and from a swab of the peritoneum taken at surgery. With initial improvement, the antibiotics were stopped. A week after admission, the patient deteriorated. CT scans demonstrated a pelvic collection with retroperitoneal extension. CT guided drainage of the collection yielded faecal fluid. She underwent resection of the sigmoid colon and Hartmann’s procedure. The antibiotics were recommenced. She developed a methicillin resistant Staphylococcus aureus (MRSA) bacteraemia. Her antibiotics were changed to vancomycin, timentin and metronidazole; however, she remained unwell. Three weeks after admission, she had further CT scans which showed a perisplenic collection, which yielded MRSA when drained. She gradually improved hereafter and was eventually discharged home 5 weeks after admission. Histological examination of the specimens obtained from the first surgical intervention confirmed a pyometrium with involvement of the fallopian tube and ovary. Examination of the specimens obtained from the sigmoid resection demonstrated diverticulosis of the sigmoid colon and localised peritonitis. Subculture of the Gram positive bacillus seen in the anaerobic blood culture bottle (BacT/ALERT 3D; bioMerieux, France) yielded small, low-convex, grey colonies on plates incubated anaerobically after 3 days. No growth was obtained on plates incubated aerobically. However, phenotypic identification did not proceed because the isolate was non-viable hereafter. The organism was subjected to 16S rRNA gene sequencing (MicroSeq500; Applied Biosystems, USA) and identified as Eggerthella lenta (98% identity over 478 bp to GenBank sequence AF292375). The isolate obtained from anaerobic cultures of the peritoneal swab was also non-viable on subculture. However, the primary plates had been discarded and thus were not available for further investigation. Eggerthella lenta is a member of the family Coriobacteriaceae. The differentiation and reclassification from other members of the genus Eubacterium was reported in 1999 on the basis of GþC content and 16S rRNA gene sequencing. Eubacterium lentum has a high GþC content (62 mol%) compared with the type species, Eubacterium limosum. Eggerthella lentum is found primarily in human faeces and is bile resistant, whereas Eubacterium exiguum is found predominantly in the mouth, in the context of periodontitis and periapical infections and is bile sensitive. 16S rRNA gene sequencing favoured the creation of a new genus, Eggerthella, to accommodate Eubacterium lentum, now renamed Eggerthella lenta gen. nov., comb. nov. The genus is named after Eggerth, the first person to isolate the organism. The cells are 0.2–0.4 6 0.2–2.0 mm, occur singly, in pairs and short chains and are Gram positive. Colonies are 0.5–2.0 mm, circular, raised to low-convex, translucent to semi-opaque, dull to shiny and smooth. The organism is an obligate anaerobe without spores or flagella. Glucose is fermented to produce acetate, lactate and succinate, phenotypically differentiating it from Propionibacterium (propionate), Lactobacillus (lactate), Actinomyces (succinate) and Bifidobacterium (acetate and lactate). Hydrogen is not produced. It is catalase negative, does not hydrolyse gelatin or aesculin but reduces nitrate. It is indole negative. In agar dilution studies performed according to National Committee of Clinical and Laboratory Standards (NCCLS) guidelines, around 40–50% of tested strains of Eggerthella lenta are inhibited by concentrations of 0.06 mg/mL or less, of amoxycillin, amoxycillin-clavulanate and clindamycin. Fewer strains still are inhibited at these concentrations of imipenem, metronidazole and moxifloxacin. The original strains of Eggerthella lenta were obtained from human faeces. Together with other anaerobes, it has also been isolated with a frequency of 50% from human appendices, whether non-inflamed, inflamed or gangrenous, as well as from the aortic walls from patients with abdominal aortic aneurysms. In both these conditions, it is unclear whether this association is pathogenic. The paucity of reported pathological associations is likely due to difficulty in cultivation and difficulty of differentiating these organisms from other non-sporulating anaerobic Gram positive bacilli. More recent studies, however, have begun to suggest both strong causal associations as well as importance in terms of frequencies. A group in Hong Kong found that Eggerthella species caused 18% of clinically significant bacteraemia due to anaerobic Gram positive bacilli. Half of these were due to E. lenta. There was a strong association with gastrointestinal disease with an Pathology (June 2008) 40(4), pp. 409–439

Evaluation of the Elecsys® Anti-HCV II assay for routine hepatitis C virus screening of different Asian Pacific populations and detection of early infection

BACKGROUND Early diagnosis of hepatitis C virus (HCV) infection is essential to allow appropriate treatment and prevent transmission. OBJECTIVES To evaluate the Elecsys(®) Anti-HCV II assay as a routine screening assay in Asia using a large number of samples from different Asian Pacific populations and compare its performance with other HCV assays routinely used in the region. STUDY DESIGN The sensitivity and specificity of the Elecsys(®) Anti-HCV II assay were determined using routine hospital samples and compared with at least one of the following comparator assays at nine independent centers: ARCHITECT™ Anti-HCV; Serodia(®)-HCV Particle Agglutination; Vitros(®) ECi Anti-HCV; Elecsys(®) Anti-HCV; ADVIA Centaur(®) HCV; InTec(®) HCV EIA; or Livzon(®) Anti-HCV. Commercially available seroconversion panels were used to assess sensitivity for early detection of infection. RESULTS The Elecsys(®) Anti-HCV II assay was more sensitive in recognizing early infection and detected acute HCV infection earlier on average than the comparator assays for all six panels tested. 7,726 routine samples were tested and 322 identified as HCV positive. Elecsys(®) Anti-HCV II had a sensitivity of 100% and a specificity of 99.66%, both of which were comparable or superior to the results obtained for competitor assays, which ranged from 87.5-100% and 98.98-100%, respectively. CONCLUSIONS The Elecsys(®) Anti-HCV II assay has the sensitivity and specificity to support its use as a routine screening method in the Asia Pacific region. Furthermore, this assay shortens the diagnostic window between infection and the detection of antibodies compared with established methods.