A longitudinal analysis of methicillin-resistant Staphylococcus aureus in a Hong Kong teaching hospital.

OBJECTIVES: To review the incidence and trends of MRSA during a 12-year (1989-2000) period at a university teaching hospital and the relationship between strain distribution by antibiogram and molecular typing. DESIGN: Retrospective review of laboratory-based surveillance records on MRSA isolation and characterization of strains by antimicrobial susceptibility and PFGE. A patient episode was counted at the time when MRSA was first isolated. SETTING: A 1,350-bed university teaching hospital in Hong Kong. PATIENTS: Those with clinical isolates of MRSA. RESULTS: During 1989 to 2000, the hospital recorded 1,203,175 deaths and discharges (D&D) and encountered 5,707 patient episodes of new MRSA isolation. The overall incidence of patient episodes of MRSA was 0.47/100 D&D. In 1989, the incidence was 0.81/100 D&D and fell to a low of 0.33/100 D&D in 1995, but then rose to 0.50/100 D&D in 2000. Antibiogram and DNA typing identified 5 major types. PFGE type A constituted 68% (211/312) of isolates and was present throughout the 12-year period. PFGE type B constituted 13% (40/312) of isolates and was only present from 1995 to 2000. These isolates form a distinct clone and had unique antibiotic resistance profiles. CONCLUSIONS: The study showed the establishment of a dominant MRSA clone (PFGE type A group) in the intensive care, medical, and surgical units and the appearance of a new MRSA strain in 1995 (PFGE type B), which partly explained the rise in incidence of MRSA cases and a disproportionate rise in MRSA bacteremia from 1995 to 2000.

Living with methicillin-resistant Staphylococcus aureus: a 7-year experience with endemic MRSA in a university hospital.

A review of our infection control records revealed 3,159 new isolations of methicillin-resistant Staphylococcus aureus (MRSA) from 1988 to 1994. Prior to this period, our approach to MRSA had changed from eradication to containment measures. We found a decline in MRSA rates from 11.4 to 5.2 first isolations per 1,000 deaths and discharges over the study period.

Varicella exposure in a neonatal intensive care unit: emergency management and control measures.

We describe an exposure of varicella zoster virus in our neonatal intensive-care unit and the emergency procedures instituted to prevent an outbreak. Fifty-seven infants and 129 staff members were exposed but none developed chickenpox. The measures included rapid identification of varicella antibody status in all neonates and those staff members with uncertain history of varicella infection; cohorting of exposed infants according to immune status; and prompt administration of varicella zoster immunoglobulin to susceptible patients. The recommendation of the American Academy of Pediatrics did not accurately predict the immune status of preterm infants, as only one of the eight susceptible infants would have qualified for immunoglobulin prophylaxis if their guidelines had been followed. Mass screening of all exposed infants using the varicella zoster enzyme linked immunosorbent assay (ELISA) test was the only reliable means of determining the immune status. Of the four risk factors evaluated for the prediction of antibody status: gestational age, postnatal age, birthweight and episodes of blood transfusion, only postnatal age was found to independently predict the immune status of our patients. Because varicella zoster susceptible staff members are difficult to identify on the basis of history, we suggest that prospective screening of staff in high-risk units be undertaken and vaccination with live varicella vaccine be offered to susceptibles.

Infection control for SARS in a tertiary paediatric centre in Hong Kong.

Severe acute respiratory syndrome (SARS) is an emerging infectious disease. After the appearance of an index patient in Hong Kong in February 2003, SARS outbreaks occurred rapidly in hospitals and spread to the community. The aim of this retrospective study is to evaluate the effectiveness of a triage policy and risk-stratified infection control measures in preventing nosocomial SARS infection among paediatric healthcare workers (HCWs) at the Prince of Wales Hospital, a general hospital to which children with SARS are referred in Hong Kong. The acute paediatric wards were stratified into three areas: (1) ultra high-risk area, (2) high-risk area and (3) moderate-risk area according to different risk levels of nosocomial SARS transmission. The implementation of different levels of infection control precautions was guided by this risk stratification strategy. Between 13 March and 23 June, 38 patients with probable and suspected SARS, 90 patients with non-SARS pneumonia, and 510 patients without pneumonia were admitted into our unit. All probable SARS cases were isolated in negative-pressure rooms. Twenty-six HCWs worked in the ultra high-risk area caring for SARS patients and 88 HCWs managed non-SARS patients in other ward areas. None of the HCWs developed clinical features suggestive of SARS. In addition, there was no nosocomial spread of SARS-associated coronavirus to other patients or visitors during this period. In conclusion, stringent infection control precautions, appropriate triage and prompt isolation of potential SARS patients may have contributed to a lack of nosocomial spread and HCW acquisition of SARS in our unit.

Successful treatment of disseminated coccidioidomycosis with amphotericin B lipid complex.

Coccidioidomycosis is endemic in regions of the Americas, but this infection may be encountered in travellers who return from an endemic region. A case is reported of a disseminated infection in a Hong Kong Chinese man, who was successfully treated with amphotericin B lipid complex (ABLC) after intolerance and toxicity precluded the use of other antifungal agents. Lipid-based formulations of amphotericin B merit further evaluation in the treatment of coccidioidomycosis and other systemic mycoses.

Combined use of alcohol hand rub and gloves reduces the incidence of late onset infection in very low birthweight infants.

OBJECTIVE: To assess the incidence of late onset (> 72 hours) infection and necrotising enterocolitis (NEC) in very low birthweight (VLBW) infants in two 36 month periods using two hand hygiene protocols: conventional handwashing (HW; first 36 month period); an alcohol hand rub and gloves technique (HR; second 36 month period). METHOD: VLBW infants admitted to the neonatal intensive care unit during the period December 1993-November 1999 were eligible. A new hand hygiene protocol using alcohol handrub and gloves was introduced in December 1996. Each patient's case record was reviewed retrospectively by two independent investigators using a standard data collection form. The incidence of NEC and systemic infections, including bacterial or fungal septicaemia, meningitis, and peritonitis, in the two periods were compared. RESULTS: The HW and HR groups contained 161 and 176 VLBW infants respectively. The incidence of late onset systemic infection decreased from 13.5 to 4.8 episodes (including NEC)/1000 patient days after introduction of the HR regimen, representing a 2.8-fold reduction. Similarly, the incidence of Gram positive, Gram negative, and fungal infections decreased 2.5-fold, 2.6-fold, and 7-fold respectively. There was also a significant reduction in the incidence of NEC in the HR group (p < 0.0001). Subgroup analysis revealed that the incidence of methicillin resistant Staphylococcus aureus (MRSA) septicaemia was significantly decreased in the second 36 month period (p = 0.048). The clinical data suggest that infants in the HW group had significantly earlier onset of sepsis (p < 0.05) and required oxygen supplementation for longer (p < 0.05) than those in the HR group. Significantly more VLBW infants were discharged from the neonatal intensive care unit without ever being infected (p < 0.0001), and also significantly fewer infants had more than one episode of infection in the HR group (p < 0.0001). CONCLUSION: The introduction of the HR protocol was associated with a 2.8-fold reduction in the incidence of late onset systemic infection, and also a significant decrease in the incidence of MRSA septicaemia and NEC in VLBW infants. This decrease in infection rate was maintained throughout the second 36 month period.

Infection control for SARS in a tertiary neonatal centre.

The Severe Acute Respiratory Syndrome (SARS) is a newly discovered infectious disease caused by a novel coronavirus, which can readily spread in the healthcare setting. A recent community outbreak in Hong Kong infected a significant number of pregnant women who subsequently required emergency caesarean section for deteriorating maternal condition and respiratory failure. As no neonatal clinician has any experience in looking after these high risk infants, stringent infection control measures for prevention of cross infection between patients and staff are important to safeguard the wellbeing of the work force and to avoid nosocomial spread of SARS within the neonatal unit. This article describes the infection control and patient triage policy of the neonatal unit at the Prince of Wales Hospital, Hong Kong. We hope this information is useful in helping other units to formulate their own infection control plans according to their own unit configuration and clinical needs.

Acute bacterial gastroenteritis: a study of adult patients with positive stool cultures treated in the emergency department.

OBJECTIVES: To investigate the presenting clinical features of acute bacterial gastroenteritis in adult patients treated as outpatients in the emergency department (ED), and the pathogens responsible in this setting and population; and to identify the frequency with which positive stool culture result changes management. METHOD: This was a retrospective study of all patients who attended the accident and emergency department of an university affiliated hospital in Hong Kong over a 12 month period, who satisfied the following inclusion criteria: (a) age >/=16, (b) presented with acute gastroenteritis, (c) treated as outpatients with or without observation, and (d) had positive stool cultures. RESULTS: One hundred and thirty patients were included. Pathogens identified were Vibrio parahaemolyticus (42.3%), Samonella spp (34.6%), Plesiomonas spp (9.2%), Campylobacter spp (6.9%), Aeromonas spp (6.9%), and Shigella spp (6.2%). Mean highest body temperature was 37.5 degrees C (95% confidence intervals (CI) 37.3 to 37.6). Bloody diarrhoea was present in 14 patients (10.8%). Mean duration of diarrhoea, from onset to the completion of stay in ED, was 2.2 days (95% CI 1.7 to 2.7). Likewise, mean duration of abdominal pain was 1.8 days (95% CI 1.5 to 2.1). Mean number of unformed stools per day was 9.3 (95% CI 8.3 to 10.3). Change of management, subsequent to the availability of positive stool culture results, was not required in 115 (88.5%) patients. Ciprofloxacin resistance occurred in eight (6.2%) cases, and seven of nine campylobacter isolates. Campylobacter positive patients had a significantly longer duration of abdominal pain (p=0.0236) and were less likely to be dehydrated (p=0.0103). CONCLUSIONS: Most patients with bacterial gastroenteritis do not present with high fever, bloody diarrhoea, or persistent diarrhoea, but generally have quite severe diarrhoea. Stool cultures do not change management for most patients. Vibrio parahaemolyticus is the commonest bacterial pathogen identified.

Severe necrotising fasciitis of the extremities caused by Vibrionaceae: experience of a Hong Kong tertiary hospital.

Necrotising fasciitis is an uncommon soft tissue infection characterised by the widespread necrosis of subcutaneous tissue and fascia, and secondary necrosis of the overlying skin. Ten patients who had necrotising fasciitis were admitted to the intensive care unit at the Prince of Wales Hospital between June 1994 and August 1997. The necrosis in six patients was caused by marine Vibrionaceae. Because of the rapid onset of necrosis, progression to severe disease, and frequently fatal outcome, the public (especially at-risk individuals), general practitioners, and specialist medical personnel should be made aware of the clinical syndrome of necrotising fasciitis caused by marine Vibrionaceae. The diagnosis is dependent on a high index of suspicion, which should be aroused by the presentation of an immunocompromised patient with an extremity lesion and a history of contact with raw seafood or a warm aquatic environment. Once the disease is suspected, treatment should be a course of a third-generation cephalosporin, and fluoroquinolone or tetracycline. Aggressive surgical debridement is recommended.

Variant Creutzfeldt-Jakob disease in Hong Kong.

A 34-year-old Chinese woman who had lived in the United Kingdom in the 1980s was admitted to hospital in Hong Kong because of a 7-month history of progressive neurological deterioration. Initially, she complained of heartburn and paraesthesia of the hands and feet. She then developed slowness of speech and gait, and was noted to be forgetful and irritable. In January 2001, she was brought back to Hong Kong for treatment. On admission in May she was dysarthric, ataxic, and dystonic. Magnetic resonance imaging showed high signals in both thalami suggestive of variant Creutzfeldt-Jakob disease. Other investigations, including electroencephalogram and lumbar puncture, were unremarkable. A tonsil biopsy showed the presence of prions. This patient's presentation is typical of the variant Creutzfeldt-Jakob disease cases that have been reported since 1996. Because of her residential history, we conclude that this is an imported case from the United Kingdom.

E-test method of antimicrobial susceptibility testing of Neisseria gonorrhoeae for routine diagnostic service.

The minimising inhibitory concentrations of four antimicrobial agents for 64 clinical isolates of Neisseria gonorrhoeae including 26 penicillinase producing strains (PPNG) as determined by E test, a recently developed method for sensitivity testing, were compared with those of agar dilution method using isosensitest (IST) agar. The medium was supplemented with either 5% lysed horse blood alone or with both lysed horse blood and 1% vitox defined supplement. The E test MICs compared closely with those obtained by agar dilution with essential agreements within +/- 1 log2 dilution being over 90% with all test antibiotics on medium that did not contain vitox, and between 71 and 93% on medium containing vitox. The Pearson's correlation coefficients ranged from 0.84 to 0.96 on either medium formulation. Excellent categorical agreement was obtained for all isolates with ceftriaxone, ciprofloxacin and tetracycline, while the E test gave a minor categorical discrepancy for two isolates with penicillin. We conclude that the E test is as reliable as conventional agar dilution method for MIC testing of N. gonorrhoeae in a routine laboratory.

Patterns of antibiotic resistance, serotype distribution, and patient demographics of Streptococcus pneumoniae in Hong Kong.

Streptococcus pneumoniae isolates from clinical specimens during the period 1993-1997 at the Prince of Wales Hospital, Hong Kong, were analysed by the antibiotic resistance profiles, the distribution of serotypes, specimen types, and patient demographics. 1,229 non-duplicate S. pneumoniae isolates were evaluated; 84% from the respiratory tract, 11% from blood and cerebrospinal fluid and the remainder from body fluids and pus swabs. The percentage of S. pneumoniae of reduced penicillin susceptibility was 38.6%, and the percentage resistance to erythromycin, chloramphenicol, co-trimoxazole and tetracycline were 40.4, 43.2, 54.9 and 77.8%, respectively. The organism was isolated from patients of all age groups, 14.6% from children aged below 10 years, half of whom were from children aged 2 years or below. 57.0% were from elderly patients aged above 60. The male to female ratio was 2.5:1. Isolates with reduced penicillin susceptibility were seen significantly more so in children under 10 than in those aged 11 or above (52 versus 36%, p < 0.0001). A diverse range of serotypes was obtained in the penicillin-susceptible isolates whilst those of reduced susceptibility were confined to serotypes 23F, 19F, 6B, 14 and 9V.

In-vitro antimicrobial susceptibility and beta-lactamases of ampicillin-resistant Escherichia coli in Hong Kong.

Three hundred and forty isolates of ampicillin-resistant Escherichia coli isolated from blood, bile and urine were collected during 1984 and 1988 in the Prince of Wales Hospital, Hong Kong and MICs of 21 beta-lactam antibiotics were determined. beta-Lactamases were identified by isoelectric focusing, and TEM-1 was found in 89.1% of isolates, PSE-1 in 3.2%, and OXA-1 in 2.9% of strains. Ten isolates (2.9%) possessed both TEM-1 and PSE-1. Five isolates (1.5%) produced only chromosomal enzymes and one produced an unidentified enzyme which focussed at pI 6.0. All but seven of 274 TEM-1 producers and all nine OXA-1 producers reacted with oligonucleotide probes in a colony blot technique. All isolates contained plasmids and 229 of 318 (72.0%) isolates transferred the ampicillin resistance factor. Of 42 transconjugants of TEM-1 producers selected for study, 39(92.9%) had only a single transferable plasmid bearing the TEM-1 gene.

Characterization of isolates of methicillin-resistant Staphylococcus aureus from Hong Kong by phage typing, pulsed-field gel electrophoresis, and fluorescent amplified-fragment length polymorphism analysis.

The genetic relatedness of 127 methicillin-resistant Staphylococcus aureus (MRSA) isolates, belonging to five major types as identified by pulsed-field gel electrophoresis (PFGE) and antibiotic resistance profiles, was examined further using phage typing and fluorescent amplified fragment length polymorphism (FAFLP). The MRSA isolates were recovered from patients at the Prince of Wales Hospital (PWH), Hong Kong, over a 13-year period, 1988 to 2000. These strains were also compared with representatives of the well-described MRSA international clones and with epidemic MRSA strains (eMRSA) 1 to 16 from the United Kingdom. Phage typing distinguished two major "clones" at this hospital: all of the phage type 1 (PT1) isolates belonged to PFGE types A, C, D, and E, while most of the PT2 isolates were associated with PFGE type B, which exhibited a unique antibiotic resistance profile. MRSA isolates belonging to PFGE subtype A2 were indistinguishable from the British eMRSA-1, while isolates of PFGE type B were closely related to eMRSA-9 by PFGE. Based on FAFLP, all five predominant PFGE types at the PWH belonged to one group and fell into the same cluster as eMRSA-1, -4, -7, -9, and -11 isolates. Multilocus sequence typing and staphylococcal cassette chromosome mec typing classified representatives of our MRSA isolates as members of the same clone (ST239-MRSA-III). Thus, the predominant MRSA isolates frin the PWH in the last decade are closely related to early United Kingdom eMRSA clones 1, 4, and 11 and are members of a lineage that includes the Brazilian MRSA clone.

Macrolide resistance in Streptococcus pneumoniae in Hong Kong.

Erythromycin resistance rates among penicillin-susceptible Streptococcus pneumoniae were 38 and 92% among penicillin-intermediate and -resistant S. pneumoniae isolates from Hong Kong, respectively, and 27% (43 of 158) of the isolates showed the MLS(B) phenotype, and the majority carried the ermB gene; 73% (115 of 158) displayed the M phenotype, and all possessed the mef gene. The MLS(B) phenotype was predominant in penicillin-susceptible, macrolide-resistant isolates and in penicillin-nonsusceptible isolates of serotype 6B, whilst the M phenotype was predominant in penicillin-intermediate or -resistant isolates belonging to serotype 23F or 19F. Extensive spread of clones of drug-resistant pneumococci has led to the widespread presence of macrolide resistance in S. pneumoniae in Hong Kong.