Serological diagnosis of Mycobacterium avium complex lung diseases by enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen.

INTRODUCTION: There is an increasing trend worldwide in the incidence of Mycobacterium avium complex pulmonary diseases (MAC-PD) and the diagnosis is sometimes complicated. Recently, an enzyme immunoassay (EIA) kit that detects serum IgA antibody against MAC-specific glycopeptidolipid (GPL) core antigen had been developed and found to be useful in discriminating MAC-PD from other lung diseases. The antibody was subsequently also found to be elevated in patients suffering Mycobacterium abscessus pulmonary diseases (MAB-PD). This study is to evaluate this EIA kit in the serological diagnosis of MAC-PD in Hong Kong Chinese patients. METHODS: The study was conducted in Grantham Hospital, Hong Kong between July 2017 and July 2018. Assay of the IgA antibody level using the EIA kit was done on blood samples collected from patients suffering from MAC-PD, MAB-PD, pulmonary tuberculosis and other lung diseases. RESULTS: There were 100 subjects recruited into the study, among which 11 were excluded. By using the cut-off value 0.7 U/mL provided by the manufacturer, the sensitivity and specificity for diagnosis were 73.7% and 77.6% for MAC-PD; 50% and 77.6% for MAB-PD. By receiver operating characteristic curves analysis, new cut-off for MAC-PD and MAB-PD were calculated as 1.771 U/mL and 0.172 U/m, respectively. The sensitivity and specificity were 68.4% and 86.2% for MAC-PD, whereas 66.7% and 72.4% for MAB-PD. CONCLUSIONS: Our study showed that the enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen could help to distinguishing MAC and M. abscessus pulmonary diseases from pulmonary tuberculosis and other lung diseases among Hong Kong Chinese patients. Further larger scale studies in our local population for the usefulness of this antibody test in the diagnosis and monitoring of MAC and M. abscessus lung diseases might be warranted.

Control of hospital endemicity of multiple-drug-resistant Acinetobacter baumannii ST457 with directly observed hand hygiene.

An increasing endemicity of multiple-drug-resistant Acinetobacter baumannii (MRAB) ST457 was noted in Hong Kong. The epidemiology, risk factors, and infection control measures to prevent nosocomial transmission of this epidemic clone were analyzed. A total of 5,058 patients cultured positive with A. baumannii between 1 January 2004 and 30 June 2014 were included, of which 297 (5.9 %) had bacteremia. The first case of MRAB bacteremia emerged in 2009, with an incidence that increased from 0.27 (one case) in 2009 to 1.86 (14 cases) per 100,000 patient-days in 2013 (p < 0.001). With the implementation of strict contact precautions and directly observed hand hygiene in conscious patients immediately before receiving meals and medications in July 2013, the incidence of MRAB bacteremia reduced from its peak to 0.77 (one case) per 100,000 patient-days in the first 6 months of 2014 (p < 0.001). Patients from long-term care facilities for the elderly [odds ratio (OR) 18.6, confidence interval (CI) 2.1-162.4, p = 0.008] and history of carbapenem (OR 7.0, CI 1.7-28.0, p = 0.006) and beta-lactam/beta-lactamase use (OR 5.6, CI 1.1-28.7, p = 0.038) 90 days prior to admission were independent risk factors for MRAB bacteremia by logistic regression when compared with carbapenem-susceptible A. baumannii bacteremia.

First report of chronic implant-related septic arthritis and osteomyelitis due to Kytococcus schroeteri and a review of human K. schroeteri infections.

We report the first case of Kytococcus schroeteri implant-related septic arthritis and osteomyelitis, identified by phenotypic tests and 16S rRNA sequencing, which responded to implant removal and doxycycline. 16S rRNA sequencing was useful for the accurate and rapid identification of the organism as it exhibited three different colonial morphologies in vitro.

Human enterovirus 71 and hand, foot and mouth disease.

Hand, foot and mouth disease (HFMD) is generally a benign febrile exanthematous childhood disease caused by human enteroviruses. The route of transmission is postulated to be faeco-oral in developing areas but attributed more to respiratory droplet in developed areas. Transmission is facilitated by the prolonged environmental survival of these viruses and their greater resistance to biocides. Serious outbreaks with neurological and cardiopulmonary complications caused by human enterovirus 71 (HEV-71) seem to be commoner in the Asian Pacific region than elsewhere in the world. This geographical predilection is unexplained but could be related to the frequency of intra- and inter-typic genetic recombinations of the virus, the host populations' genetic predisposition, environmental hygiene, and standard of healthcare. Vaccine development could be hampered by the general mildness of the illness and rapid genetic evolution of the virus. Antivirals are not readily available; the role of intravenous immunoglobulin in the treatment of serious complications should be investigated. Monitoring of this disease and its epidemiology in the densely populated Asia Pacific epicentre is important for the detection of emerging epidemics due to enteroviruses.

Differential susceptibility of different cell lines to swine-origin influenza A H1N1, seasonal human influenza A H1N1, and avian influenza A H5N1 viruses.

BACKGROUND: The novel swine-origin influenza A H1N1 virus (S-OIV) causes the current pandemic. Its tissue tropism and replication in different cell lines are not well understood. OBJECTIVE: Compare the growth characteristics of cell lines infected by S-OIV, seasonal influenza A H1N1 (sH1N1) and avian influenza A H5N1 (H5N1) viruses and the effect of temperature on viral replication. STUDY DESIGN: Cytopathic effect (CPE), antigen expression by immunofluorescence (IF) and viral load profile by quantitative RT-PCR in 17 cell lines infected by S-OIV, sH1N1 and H5N1 were examined. Comparison of their replication efficiency in chick embryo was performed. The effect of temperature on viral replication in Madin-Darby canine kidney (MDCK) cells was determined by TCID(50) at 33 degrees C, 37 degrees C and 39 degrees C for 5 consecutive days. RESULTS: S-OIV replicated in cell lines derived from different tissues or organs and host species with comparable viral load to sH1N1. Among 13 human cell lines tested, Caco-2 has the highest viral load for S-OIV. S-OIV showed a low viral load with no CPE or antigen expression in pig kidney cell PK-15, H5N1 demonstrated the most diverse cell tropism by CPE and antigen expression, and the highest viral replication efficiency in both cell lines and allantoic fluid. All three viruses demonstrated best growth at 37 degrees C in MDCK cells. CONCLUSION: Cell line growth characteristics of S-OIV, sH1N1 and H5N1 appear to correlate clinically and pathologically with involved anatomical sites and severity. Low replication of S-OIV in PK-15 suggests that this virus is more adapted to human than swine.

Examination of seroprevalence of coronavirus HKU1 infection with S protein-based ELISA and neutralization assay against viral spike pseudotyped virus.

BACKGROUND: Human coronavirus HKU1 (HCoV-HKU1) is a recently identified coronavirus with a global distribution and known to cause mainly respiratory infections. OBJECTIVES: To investigate the seroepidemiology of HKU1 infections in our local population. STUDY DESIGN: An ELISA-based IgG antibody detection assay using recombinant HCoV-HKU1 nucleocapsid and spike (S) proteins (genotype A) were developed for the diagnosis of CoV-HKU1 infections, Additionally, a neutralization antibody assay using the HCoV-HKU1 pseudotyped virus was developed to detect the presence of neutralizing antibodies in serum with antibody positivity in an S protein-based ELISA. RESULTS: Results of the recombinant S protein-based ELISA were validated with Western blot, immunofluorescence analysis and flow cytometry. The coupled results demonstrated good correlation with Spearmen's coefficient of 0.94. Seroepidemiological study in a local hospital-based setting using this newly developed ELISA showed steadily increasing HCoV-HKU1 seroprevalence in childhood and early adulthood, from 0% in the age group of <10 years old to a plateau of 21.6% in the age group of 31-40 years old. CONCLUSIONS: Our study demonstrated the usefulness of the S-based ELISA which could be applied to future epidemiological studies of HCoV-HKU1 in other localities.

Non-tuberculous mycobacterial infection in patients with systemic lupus erythematosus.

OBJECTIVES: Patients with systemic lupus erythematosus (SLE) are susceptible to opportunistic infections. To examine the clinical manifestations of non-tuberculous mycobacterial (NTM) infections with those of Mycobacterium tuberculosis (MTB) infections in SLE patients. METHODS: Medical records of a cohort of 725 SLE patients were reviewed for previous NTM infections. Demographic characteristics, predisposing factors and clinical outcomes were compared with patients who had previous MTB infections (n = 39). RESULTS: Eleven (nine female and two male) cases were identified (prevalence 1.5%). The mean +/- S.D. age at the time of infection was 42.8 +/- 13.9 yrs, 9.3 +/- 5.8 yrs after the onset of SLE. The mean +/- S.D. time taken from onset of symptoms to the diagnosis of NTM infection was 5.7 +/- 7.2 months. Sites of involvement included skin and soft tissue (n = 8), chest (n = 2) and disseminated infection (n = 1). NTM infections were more likely to involve extrapulmonary sites (P = 0.006), presented in patients with longer lupus disease duration (P < 0.001), occurred in older patients (P < 0.001) and in those who had a higher cumulative dose of prednisolone (P = 0.01) than MTB infections. Using a stepwise logistic regression, disease duration was found to be the only independent predictive factor (P = 0.005) for NTM infections. Ten (25.6%) patients with MTB infections but none of the patients with NTM infections presented concomitantly at the onset of SLE (P = 0.09). There were no differences in the recurrence rate (P = 0.64) and frequency of disseminated infections (P = 0.40) between NTM and MTB infections. CONCLUSIONS: NTM infections tended to develop in SLE patients later in their disease course than MTB infections. A high index of suspicion is required for its diagnosis.

Influenza vaccination: options and issues.

Currently available vaccines have similar efficacy if they are matched to the most prevalent circulating strains. They also have comparable adverse effect profiles. The choice of a specific preparation of vaccine therefore requires consideration of cost, purity of the vaccine preparation in terms of the amount of egg protein and endotoxin, allergy to different constituents of the vaccine, reactogenicity profiles, as well as the preferred route of administration. Intradermal injection of the vaccine appears to be a viable alternative to the traditional intramuscular administration with the additional benefit of requiring a smaller volume of vaccine. Despite the documented benefits in various community and institutional settings, influenza vaccination has been underutilised by most target groups. A major obstacle to broader coverage of vaccination is the perceived ineffectiveness of the vaccine and the relatively benign nature of the illness in most patients. Uptake of vaccine among target populations, especially health care workers, needs to be improved through a concerted effort between frontline clinicians and health authorities.

Human infection by avian influenza A H5N1.

The Southeast Asian outbreak of the highly lethal avian influenza A H5N1 infection in humans is unlikely to abate because of the enormous number of backyard farms providing poultry as the main source of food protein in developing countries. This increases the risk of the emergence of a reassortant pandemic influenza virus with improved human-to-human transmissibility. Currently triage of suspected cases by epidemiological risk factors remains the only practical way of case identification for laboratory investigation and infection control. The clinical usefulness of rapid diagnostic laboratory tests requires more vigorous evaluation. The lethality of this disease may reflect systemic viral dissemination, cytokine storm, or alveolar flooding due to inhibition of cellular sodium channels. The present circulating genotype Z is intrinsically resistant to amantadine and rimantadine. Prognosis may be improved by early treatment with a neuraminidase inhibitor with good systemic drug levels, and post-exposure prophylaxis for health care workers is recommended. The role of immunomodulators and other modalities of therapy requires evaluation in randomised controlled trials, with prospective monitoring of the viral load and cytokine profiles in various clinical specimens. In view of the high fatality of the disease, a combination of contact, droplet, and airborne precautions are recommended as long as resources allow despite the fact that the relative importance of these three modes in nosocomial transmission of avian influenza is still unknown.

Unilateral epistaxis after swimming in a stream.

A 55-year-old Chinese woman presented with a 3-week history of unilateral left-sided epistaxis and nasal obstruction. She had swam in a freshwater stream 1 month prior to the onset of symptoms. Endoscopic examination revealed a live leech at the left middle meatus with a large part of its body inside the left maxillary antrum. Local anaesthetic was applied to anaesthetise the leech and facilitate removal. Magnetic resonance imaging performed following removal confirmed that no other leeches were present in the sinonasal area. The endoparasitism might have persisted because of the inconspicuous site of infestation and the absence of pain. This form of leech infestation has not been previously reported.

Disseminated ochroconis gallopavum infection in a renal transplant recipient: the first reported case and a review of the literature.

Ochroconis gallopavum is a potentially fatal dematiaceous fungus causing opportunistic infections in immunocompromised hosts. We report the first case of disseminated O. gallopavum infection in a 13-year-old renal transplant recipient, which involved the brain, lung and spleen. He was treated with amphotericin B, itraconazole and voriconazole, a new antifungal agent first used to treat such an infection. Besides antifungal treatment, all immunosuppressive agents were stopped and automated peritoneal dialysis was resumed. The initial infection was under control with both clinical and radiological improvements after treatment. However, the patient later acquired Acremonium spp. peritonitis; he failed to respond to high-dose amphotericin B, and finally succumbed. A total of 13 reported O. gallopavum human infections, including the one described here, are reviewed. The most common site of involvement is the brain and the crude mortality rate is up to 46%. As the disease is potentially lethal in immunocompromised hosts, empirical antifungal coverage should be considered in post-renal transplant recipients with suspected brain abscess. Early biopsy of lesion for histopathological and microbiological diagnosis would be essential in managing such cases.

Continuous ambulatory peritoneal dialysis-related peritonitis caused by Streptococcus bovis.

The first case of Streptococcus bovis peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD) in a 40-year-old Chinese woman suffering from systemic lupus erythematosus is reported. Streptococcus bovis is part of the normal flora in the human intestine and, less commonly, the female genital tract. Being a rare cause of peritonitis, the possible link between genital tract colonization by Streptococcus bovis and retrograde invasion of the peritoneal cavity is postulated to be the cause of continuous ambulatory peritoneal dialysis peritonitis in this patient. Since invasive Streptococcus bovis infection is associated with gastrointestinal pathology (Streptococcus bovis biotype I) and chronic liver diseases (Streptococcus bovis biotype II), identifying the biotype of Streptococcus bovis could guide treatment by indicating that further investigation of these underlying diseases is required.

Staphylococcus aureus subcutaneous abscess complicating acupuncture: need for implementation of proper infection control guidelines.

We report a case of Staphylococcus aureus subcutaneous abscess centered over the Jizhong acupuncture point (DU 6) which lies along the Du (Back midline) meridian after acupuncture at the corresponding acupuncture point for low back pain. The patient recovered after surgical debridement and drainage and 5 weeks of cloxacillin therapy. Among the 16 anecdotal case reports of pyogenic bacterial infections complicating acupuncture described in the English literature (MEDLINE Search 1996-2002), S. aureus was documented to be the causative agent in 9 (56%). Three patients had septic arthritis, 2 had chronic osteomyelitis, 2 had abscess formation, 1 had chondritis, and 1 had infective endocarditis. Five patients had S. aureus bacteremia. All patients who recovered required prolonged antibiotic treatment of 5-6 weeks, and 6 required drainage and/or debridement. Overall, 3 patients (30%) died. S. aureus causes significant morbidity and mortality in patients who receive acupuncture treatment. More resources should be spent on implementation of proper infection control guidelines, as the money lost due to prolonged hospitalization and medication would far exceed that used for implementation.