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Biomedical subjects

A F Cheng

Publications and source records attributed to A F Cheng.

At least 127 records · Page 7Linked to original sources
PubMed1993

Epidemiology and etiology of pneumonia in children in Hong Kong.

The epidemiologic and etiologic features of cases of pneumonia among 1,740 children admitted to a teaching hospital in Hong Kong over a 3-year period were studied. Of the patients, 23% were < 1 year old and 69% were < 5 years old. The incidence of pneumonia requiring admission to the hospital was 6.4 episodes per 1,000 children per year for those < 5 years of age. The overall case fatality rate was 0.15% among patients who did not have severe underlying disease before contracting pneumonia. A bacterial etiology was confirmed by blood culture for only 2% of patients. However, culture of sputum or nasopharyngeal aspirates yielded predominant or pure growth of one bacterial agent in 17% of cases. Haemophilus influenzae was the bacterial agent most frequently isolated from nasopharyngeal aspirates or sputum, followed by Streptococcus pneumoniae and Staphylococcus aureus. Of the H. influenzae isolates, 38% were resistant to ampicillin. A viral etiology was proven in 9.1% of cases, and evidence of mycoplasmal infection was found in 3.8% of cases. Respiratory syncytial virus was the most frequently identified viral agent, followed by adenovirus and influenza A virus.

Adolescent↗
PubMed1993

The antimicrobial activity and beta-lactamase stability of cefpirome, a new fourth-generation cephalosporin in comparison with other agents.

The antimicrobial activity of cefpirome was compared with amoxycillin/clavulanic acid, ampicillin/sulbactam, cefuroxime, ceftazidime, gentamicin and amikacin against 743 non-duplicate clinical isolates. MIC50 and MIC90 showed that the antibiotic was active against both Gram-negative and Gram-positive organisms. Cefpirome was highly active against most of the Enterobacteriaceae, including indole-positive Proteus spp., Aeromonas spp. (MIC < or = 1 mg/L) and Salmonella spp. (MIC < or = 0.5 mg/L). Neisseria gonorrhoeae and Haemophilus influenzae (including beta-lactamase producers) were all susceptible, with MIC less than 0.5 and 0.25 mg/L respectively. Cefpirome was more active than cefuroxime and ceftazidime against Campylobacter spp. (MIC < or = 2 mg/L), but less active than ceftazidime against Pseudomonas aeruginosa. Cefpirome was active against Streptococcus pneumoniae. Streptococcus bovis and coagulase-negative staphylococci (MIC < or = 0.5 mg/L) and methicillin-sensitive Staphylococcus aureus (MIC < or = 2 mg/L). Methicillin-resistant S. aureus, Gram-positive and Gram-negative anaerobes were resistant to cefpirome. The stability of cefpirome to TEM-1, TEM-2, PSE-1, SHV-1 and the chromosomal-mediated P99 and K-1 beta-lactamases was comparable to ceftazidime.

Acinetobacter↗
PubMed1993

Salmonella bacteraemia occurring concurrently with the first presentation of systemic lupus erythematosus.

There is increasing recognition of the association between Salmonella infections and systemic lupus erythematosus (SLE). However, these infections have usually occurred in patients with established SLE who were receiving immunosuppressive therapy. We describe two young women with previously undiagnosed SLE who developed Salmonella bacteraemia. Neither of these patients had received immunosuppressive drugs. From these and two previously reported patients, it may be concluded that SLE per se is likely to be associated with a defect in host defences to Salmonella bacteria.

Adult↗
PubMed1993

Postantibiotic effects of amikacin and ofloxacin on Mycobacterium fortuitum.

A study of postantibiotic effects (PAE) in vitro of amikacin and ofloxacin on Mycobacterium fortuitum isolates from sternotomy wounds by use of the dilution method for drug removal showed that both drugs exhibited good bactericidal activities, with the PAE of amikacin lasting from 13.5 to 27.6 h and the PAE of ofloxacin lasting from 1.2 to 5.0 h. These laboratory results concur with our experience of the efficacy of once-daily dosing with these drugs in the treatment of infections caused by M. fortuitum. These data may have therapeutic implications in guiding the scheduling of the administration of drugs in these infections, which require a long duration of therapy.

Amikacin↗
PubMed1993

Correlation of serum ofloxacin concentration and serum creatinine level in patients on prolonged therapy.

Serum ofloxacin concentrations were assessed by high performance liquid chromatography 4 h after drug administration in 86 patients with pulmonary tuberculosis. All patients had multidose, once-daily drug administration (200 mg to 800 mg p.o.) for at least 3 weeks prior to assessment. The serum creatinine levels were simultaneously assessed for these patients. A positive correlation was found between serum ofloxacin (Y) and serum creatinine x dose of ofloxacin administered/body surface area (X). The correlation can be represented mathematically by the equation: Y = 0.87X + 0.68 (r = 0.80, p < 0.001).

Adolescent↗
PubMed1993

Lack of activities of amikacin and sulphamethoxazole against Mycobacterium avium-intracellulare.

Twenty clinical isolates of Mycobacterium avium-intracellulare were tested with amikacin and sulphamethoxazole for in-vitro susceptibilities. The MICs and MBCs of the former drug ranged from 8 to > 64 mg/L (median MIC: 64 mg/L, median MBC: > 64 mg/L). The MICs and MBCs of the latter drug were found to be > 256 mg/L. Each of eight patients with invasive pulmonary disease due to these organisms was treated with amikacin for six months and with cotrimoxazole (sulphamethoxazole-trimethoprim) for one year. Only one patient had sustained bacteriological conversion. Three patients showed a transient reduction of bacillary load during the period of amikacin administration. The rest all failed to show response. Thus sulphamethoxazole was found to have no activity against Mycobacterium avium-intracellulare, and amikacin has doubtful activity when used alone in treatment of M. avium-intracellulare infection.

Adult↗
PubMed1993

Infectious diarrhoea in Hong Kong.

The role of enteric pathogens in diarrhoeal patients presenting at a large general hospital in Hong Kong from May 1984 to December 1990 was assessed. A total of 3267 organisms were isolated. The gastroenteric salmonellae were the most common pathogens (45%), followed by rotavirus (34%) and campylobacters (11%). Shigellae or vibrios constituted 5% or less of the total isolations. Both salmonellae and campylobacters were isolated more often from infants while rotavirus was more common in young children aged 1-4 years. Shigellae commonly affected young adults and vibrios mainly older patients. Rotavirus was most commonly isolated in the winter months while salmonellae and vibrios were more common in the hotter months. There was no seasonal predominance for shigellosis. Multiple infections occurred in 86 patients (3% of total cases); 42 of these patients had concurrent Salmonella and rotavirus infections and 22 had Campylobacter and rotavirus infections. Salmonellae remain a major public health problem in Hong Kong.

Adolescent↗
PubMed1992

Epidemiology and aetiology of acute bronchiolitis in Hong Kong infants.

The epidemiological, clinical and virological features of 1220 children with acute bronchiolitis admitted to the Prince of Wales Hospital, Hong Kong, from 1985 to 1988 are reported. They accounted for 6.6% of total paediatric admissions and provided a case incidence of bronchiolitis requiring admission to hospital of approximately 21 per 1000 children 0-24 months of age. The clinical course and outcome was in general benign. The average hospital stay was 5 days and there were no deaths. Ten per cent of patients were repeatedly admitted to hospital with recurrent wheezing after discharge. Two infants developed bronchiolitis obliterans. Respiratory syncytial virus (RSV) was shown by direct immunofluorescence, virus culture and serology to be the commonest cause of acute bronchiolitis in Hong Kong. Other aetiological agents included parainfluenza and influenza viruses, adenoviruses, and Mycoplasma pneumoniae. In contrast to western countries, a seasonal variation of bronchiolitis was found with a peak incidence in the summer months. The significance of these observations is discussed.

Acute Disease↗
PubMed1992

Effect of biliary obstruction on the hepatic excretion of imipenem-cilastatin.

The biliary excretion of imipenem-cilastatin studied by endoscopic cannulation of the common bile duct in patients with complete obstruction and in a group without obstruction showed that despite a 24-h prophylaxis, the bile obtained from patients with obstruction immediately after cannulation contained neither imipenem nor cilastatin, while there were 2 and 5% of peak concentrations in serum for imipenem and cilastatin, respectively, in the bile from patients without obstruction. Biliary excretion of both compounds increased rapidly after decompression, reaching a maximum of 15% of peak levels in serum within 2 h. Twenty-four hours after drainage, the biliary excretion of the drugs further improved. We conclude that since biliary obstruction impairs excretion of antibiotics, drainage is necessary for the control of sepsis in obstructed cholangitis.

Adult↗
PubMed1992

Mycobacteria as a cause of infective exacerbation in bronchiectasis.

In 91 patients with bronchiectasis seen over 6 years, a positive mycobacterial culture was obtained in 12 cases (13%). The organisms isolated were Mycobacterium tuberculosis in nine cases, Mycobacterium avium in two cases and Mycobacterium tuberculosis and chelonei were obtained on separate occasions in one case. Computed tomography and/or bronchography showed that the bronchiectatic changes commonly involved the lower lobes and to a lesser extent, the middle and lingula lobes. In none of these 12 cases was tuberculosis strongly suspected on clinical or radiological grounds. We conclude that mycobacterial infections are common in patients with bronchiectasis and sputum should be cultured for mycobacteria periodically in these patients. In doubtful cases, bronchoscopy may be helpful to obtain a positive mycobacterial culture.

Adult↗
PubMed1992

Development of trimethoprim-resistance in Salmonella typhi during therapy.

A typhoid patient was infected with a fully-sensitive, plasmidless strain of Salmonella typhi which acquired resistance to kanamycin, sulfamethoxazole and trimethoprim during cotrimoxazole therapy. The resistant post-treatment strain harboured 4 plasmids of 62, 4.1, 3.8 and 3.0 Md in size. Kanamycin-, sulfamethoxazole- and trimethoprim-resistance were borne on a transferable 62 Md plasmid which was compatible with groups FI, FIme, FII, FIV, H1, H2, B, I1, I2, J, K, M, N, T, X, W and P. Sulfamethoxazole-resistance was also borne on the 4.1 Md plasmid. The 3.8 Md plasmid was not transferable; the 3.0 Md plasmid was transferable but did not confer antibiotic resistance. Excluding the strain described here, only 5 out of 35 other S typhi isolates contained plasmids. This is the first report of trimethoprim-resistant S typhi in Hong Kong.

Adult↗
PubMed1992

The laboratory diagnosis of rickettsial diseases in Hong Kong.

Indirect immunoperoxidase (IP) tests against antigens of Rickettsia typhi, R. sibirica and R. tsutsugamushi were carried out on serum samples from 10 patients known to have high titres against one or more Proteus OX antigens in the Weil-Felix (WF) test. The IP test confirmed rickettsial infection in nine of the 10 patients, giving unequivocal indications of the grouping of the infecting Rickettsia species and, in one instance, showing a diagnostic IgM titre in a specimen taken on day 3 of the patient's illness. IP tests confirmed four cases of spotted fever group rickettsial infection, three cases of urban or murine typhus and two of scrub typhus.

Adolescent↗
PubMed1992

Bronchoscopy and tuberculostearic acid assay in the diagnosis of sputum smear-negative pulmonary tuberculosis: a prospective study with the addition of transbronchial biopsy.

A prospective study of the efficacy of bronchoscopy and tuberculostearic acid assay in the diagnosis of sputum smear-negative pulmonary tuberculosis (TB) was carried out in 39 patients with symptoms and radiographic changes suggestive of active pulmonary TB. The diagnosis of TB was confirmed in 15 patients, probable TB was diagnosed in eight and 16 patients did not have TB. An early diagnosis of TB was made by bronchoscopy in six patients (40 per cent). Culture of sputum obtained before bronchoscopy was positive in nine patients (60 per cent) while combined with bronchoscopy specimens, a positive mycobacterial culture was obtained in 12 patients (80 per cent). Mycobacteria were cultured from transbronchial biopsy specimens from five patients (33 per cent) but none of these was exclusively positive. Histological examination of transbronchial biopsy tissue was diagnostic of TB in four patients and it was the exclusive means of early diagnosis in two. Transbronchial biopsy also provided an alternative diagnosis in four other patients. Tuberculostearic acid assay had a sensitivity of 0.40 in bronchial aspirate, 0.80 in bronchoalveolar lavage fluid, and 0.27 in transbronchial biopsy specimens: the combined result was 0.87. In nine patients with pulmonary TB in whom an early diagnosis could not be made, the tuberculostearic acid assay was positive in seven (78 per cent). We conclude that bronchoscopy with bronchoalveolar lavage and transbronchial biopsy is helpful in providing early diagnosis and positive culture results. Assay of tuberculostearic acid in bronchoalveolar lavage fluid is a useful adjunct to early diagnosis. However, mycobacterial culture and assay of tuberculostearic acid in transbronchial biopsy specimens have little diagnostic value.

Adolescent↗
PubMed1992

Common bile duct stones: a cause of chronic salmonellosis.

A chronic carrier state of Salmonella spp is present in 0.15% of the population, and is believed to be related to the presence of a diseased gallbladder. We present a patient with common bile duct (CBD) stones, whose bile cultures repeatedly indicated Salmonella typhi, despite an adequate course of antibiotic treatment. The carrier state was abolished after removal of the CBD stones 4 months later. The chronic carrier state may be related to biofilm formation on the surface of the CBD stones. The removal of the biliary stones, which are the most likely reservoir for Salmonella spp, may be a crucial step in eradication of the carrier state.

Aged↗
PubMed1991

Measurement of the costs of hospital infection by prevalence surveys.

Data from seven single-day prevalence surveys were used to assess the costs of hospital-acquired infection (HAI) by matching infected cases with controls and reviewing patient case notes for details of mortality, length of hospitalization and antibiotic treatment costs. Many cases with a high risk of HAI could not be matched and probably had inevitable infection. Cases that could be matched had the same risks of HAI as the controls, and these infections were potentially avoidable. Compared with controls, infected patients had an excess mortality rate of 7.4%, an average excess hospital stay of 23 days and an average excess antibiotic expenditure of US$190. By extrapolation we calculate that the annual costs of avoidable HAI at Prince of Wales Hospital is now approximately 130 lives, 42 000 bed-days and US$0.3m of antibiotics; costs of a similar magnitude have already been saved by a programme of hospital infection control. We conclude that hospital-acquired infection is very expensive, infection control is highly cost-effective, and prevalence surveys are practical tools for the measurement of rates and costs of hospital infection.

Adult↗