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Biomedical subjects

G L French

Publications and source records attributed to G L French.

At least 73 records · Page 4Linked to original sources
PubMed1991

Antimicrobial susceptibilities and beta-lactamase production of Hong Kong isolates of gastroenteric salmonellae and Salmonella typhi.

We examined the in-vitro antibiotic susceptibility of 760 gastroenteric salmonellae and 36 strains of Salmonella typhi isolated in Hong Kong between 1985 and 1988. S. typhi remained susceptible to all the antibiotics tested except for one isolate resistant to chloramphenicol, another to kanamycin and co-trimoxazole, and a third to nalidixic acid. In contrast, resistance and multiple resistance has increased significantly in gastroenteric salmonellae over the last ten years. Seventeen percent were resistant to ampicillin, 61% to tetracycline, 23% to chloramphenicol and 8% to gentamicin. Many ampicillin-resistant strains remained resistant to ampicillin even in the presence of sulbactam (69%) or clavulanic acid (25%). More than 50% of isolates were resistant to two or more antibiotics and one isolate was resistant to eleven. Ampicillin-resistance was usually due to the production of TEM-1 or OXA-1 beta-lactamases but a few isolates produced AER-1, PSE-1 or PSE-2. Genetic determinants for these enzymes were usually borne on plasmids ranging in size from 2 to 143.7 Md but half of the OXA-1 genes were chromosomally located.

Ampicillin Resistance↗
PubMed1991

Diagnosis of tuberculous pleural effusion by the detection of tuberculostearic acid in pleural aspirates.

Detection of TBSA was attempted in pleural aspirates of 74 patients with tuberculous and 44 patients with nontuberculous pleural effusion by gas chromatography/mass spectrometry with selected ion monitoring. The results were disappointing with a test sensitivity of 67.6 percent and a specificity of 52.3 percent. In contrast, histologic examination of pleural biopsies gave a diagnostic sensitivity of 71.0 percent. Pleural biopsy remains a better investigational procedure for the diagnosis of tuberculous pleural effusion.

Biopsy↗
PubMed1991

A five-year prospective study of septicaemia in hospitalized children in Hong Kong.

In a 5-year prospective study in a Hong Kong teaching hospital there were 344 clinically significant episodes of paediatric septicaemia. Many of the microbiological and clinical features were similar to those reported in Japanese and Western studies but there were some important differences. Half of the episodes (or 70% if neonatal infections are excluded) were community-acquired. The commonest organisms found were Salmonella spp (15% of all and 27% of community-acquired infections); this was related to the high local incidence of salmonellosis and typhoid fever. Salmonella typhi, which was responsible for one-third of the salmonella septicaemias, was usually seen in school-age children, while non-typhoid salmonellae were common in infants. Methicillin-resistant Staphylococcus aureus, which are now endemic in Hong Kong hospitals, was a common cause of hospital-acquired septicaemia. Pneumococcal septicaemia accounted for 22% of episodes in infants and pre-school children, but Haemophilus influenzae was uncommon (2% of all episodes) and there was no case of meningococcal septicaemia. The rarity of invasive infection with H. influenzae and Neisseria meningitidis in Hong Kong children is unexplained.

Adolescent↗
PubMed1990

Infective endocarditis caused by Streptococcus suis serotype 2.

Infective endocarditis caused by Streptococcus suis serotype 2 is not uncommon in pigs but is rare in human beings. We describe the case of a pig-farmer with endocarditis due to S. suis serotype 2 and in whom prolapse of the mitral valve was the predisposing cardiac lesion. Streptococcus suis, a possible cause of infective endocarditis in endemic areas, may be confused with other group D streptococci. In suspected cases a history of contact with pigs or raw pork should be sought.

Agricultural Workers' Diseases↗
PubMed1990

Hong Kong strains of methicillin-resistant and methicillin-sensitive Staphylococcus aureus have similar virulence.

While most authorities agree that methicillin-resistant Staphylococcus aureus (MRSA) are as pathogenic as methicillin-sensitive strains (MSSA), some believe that MRSA are relatively avirulent opportunists, and that their importance has been exaggerated. We present evidence that Hong Kong strains of MRSA and MSSA are equally pathogenic: they have similar virulence in animal models; they are isolated in similar proportions from both deep and superficial clinical sites including blood; in patients with hospital-acquired bacteraemias mortality rates are similar when adjusted for clinical factors; and in both animals and patients with systemic MRSA infection, mortality rates are significantly reduced by vancomycin therapy. Efforts to control the spread of MRSA are justified, and in invasive sepsis early treatment with vancomycin may be life-saving.

Animals↗
PubMed1990

Outbreaks of infection with methicillin-resistant Staphylococcus aureus on neonatal and burns units of a new hospital.

Multiple introductions of methicillin-resistant Staphylococcus aureus (MRSA) strains occurred to a new hospital in Hong Kong. Two years of clinical microbiological surveillance of the resulting outbreaks was combined with laboratory investigation by phage and antibiogram typing, and plasmid profiling. The outbreaks on the special care baby (SCBU) and burns (BU) units were studied in detail, and colonization of staff and contamination of the environment were investigated. MRSA were spread by the hands of staff on the SCBU, where long-term colonization of dermatitis was important, but were probably transmitted on the BU by a combination of the airborne, transient hand-borne and environmental routes. Simple control measures to restrict hand-borne spread on the SCBU were highly effective, but control was not successful on the BU.

Burn Units↗
PubMed1990

The effect of obstruction on the biliary excretion of cefoperazone and ceftazidime.

The biliary excretion of cefoperazone and ceftazidime was studied by endoscopic cannulation of the common bile duct, in patients with complete biliary obstruction and in an unobstructed control group. Patients were given each drug prophylactically for 24 h before endoscopy and as a single dose at the time of cannulation. In unobstructed patients biliary excretion of ceftazidime was passive. At the time of cannulation bile contained 10% of the peak serum concentration, rising to 20% 90 min later. Cefoperazone excretion was active. At cannulation biliary concentrations were 200% of the serum peak, 900% at 60 min and 700% at 90 min. In obstructed patients, bile sampled immediately at decompression contained neither antibiotic. Passive excretion of both drugs occurred rapidly after relief of obstruction and biliary concentrations were 20% of maximum serum levels at 60 min. Twenty-four hours later passive excretion had further improved, but the active excretion mechanism of cefoperazone had still not recovered. We conclude that obstruction impairs active as well as passive biliary excretion of antibiotics, that drainage is essential for the control of sepsis in obstructed cholangitis, and that both cefoperazone and ceftazidime achieve similar and therapeutic concentrations in bile during the 24 h after decompression.

Adult↗
PubMed1990

Septicaemia in Hong Kong.

In a five-year prospective study of blood culture-positive septicaemia in a Hong Kong teaching hospital there were 2211 clinically-significant episodes, of which 16% occurred in children less than 15 years old. The microbiology and clinical features were broadly similar to those seen in Europe and North America, but with some important differences. Two-thirds of episodes were community-acquired. The most common organism isolated from community-acquired septicaemias was Escherichia coli and the source, most commonly, the urinary tract. However, the biliary tract was the second most common source of community-acquired infection (25%), reflecting the frequency of liver disease in Hong Kong. Three per cent of community-acquired septicaemias were associated with endocarditis; half of these were with viridans streptococci, usually in patients with rheumatic heart disease, and 40% were in drug addicts with methicillin-sensitive Staphylococcus aureus. The commonest organisms causing community-acquired childhood infections were Salmonella spp. (27%) and Streptococcus pneumoniae (22%), whereas pneumococci accounted for only 3% of adult community-acquired micro-organisms. Haemophilus influenzae infections were uncommon and there was no case of meningococcal or gonococcal septicaemia. The commonest cause of hospital-acquired septicaemia was Staph. aureus (24%), of which 46% were methicillin-resistant. The characteristics of septicaemia in Hong Kong are influenced by the patient population structure, endemic disease patterns, local medical practice and socio-economic factors, but the rarity of Str. pneumoniae in adults and of H. influenzae and Neisseria meningitidis in children is unexplained.

Adolescent↗
PubMed1990

Rapid diagnosis of bacterial meningitis by the detection of a fatty acid marker in CSF with gas chromatography-mass spectrometry and selected ion monitoring.

A chemical marker of bacterial meningitis was sought by comparing derivatives of sterile cerebrospinal fluid (CSF) with cultures of organisms in spinal fluid and artificial media. The technique of gas chromatography-mass spectrometry with selected ion monitoring (GC-MS-SIM) was used, optimised for the analysis of fatty acids. Twenty candidate ions were screened, and an ion of mass: charge ratio (m/e) 268 was chosen for detection in clinical specimens. The origin of this marker is unknown, but it is probably the molecular ion of a C16:1 fatty acid. In 135 clinical specimens of CSF examined, the m/e 268 ion was found to be a useful marker for the common organisms that cause bacterial meningitis, giving a sensitivity of 88% and a specificity of 98%. The method was more rapid and more sensitive than conventional microscopy and culture, but CSF containing coagulase-negative staphylococci, Mycobacterium tuberculosis, Cryptococcus neoformans and some other uncommon pathogens gave inconsistent results. Many organisms produced characteristic ion profiles with multiple-ion monitoring, and this method of chemical analysis holds promise for the rapid diagnosis of bacterial infections to genus or species level.

Biomarkers↗
PubMed1990

Comparison of methods for the diagnosis of typhoid fever.

Over five years the Bactec radiometric blood culture method yielded Salmonella typhi in 41 of 45 confirmed cases of typhoid fever, 90% of which were from the first culture set taken. Blood clot culture was positive in 18 (41%) of 44 confirmed cases and stool culture in 24 (59%) of 41. The yield from 2189 Widal clot cultures was only 0.03%. There were 68 positive results in 2258 unpaired Widal tests: 23 of them were falsely positive and 13 falsely negative, but in 11 out of 68 cases the Widal was the only positive laboratory test. It is concluded that routine clot culture is not cost effective if a sensitive blood culture method is used, and that the Widal test is useful only in selected patients.

Agglutination Tests↗
PubMed1990

Evaluation of Cathra system for identifying gram negative aerobic bacteria.

The Cathra system is a commercial multipoint inoculation method for the identification of aerobic Gram negative bacteria. The system uses a replicator technique in which 21 different agar media can be inoculated simultaneously with 36 organisms. Identifications are made by use of a special computer database. The performance of this system was compared with that of the API 20E for the identification of 372 clinical isolates of Enterobacteriaceae and 133 miscellaneous Gram negative bacteria. For enterobacteria, the Cathra system was in 97% agreement with API 20E at species level and 98% at genus level. For miscellaneous Gram negative strains the two systems were in 59% agreement at species level and 77% at genus level. The Cathra system is suitable for use in diagnostic laboratories, especially those with a heavy workload and a wish to use break-point sensitivity testing. The identification database for miscellaneous Gram negative organisms, however, needs to be expanded.

Bacteriological Techniques↗
PubMed1989

Repeated prevalence surveys for monitoring effectiveness of hospital infection control.

In a 1400-bedded teaching hospital single-day prevalence surveys of hospital infection were done every six months for 3 years. The prevalence of community-acquired infection remained constant; but, after the introduction of a general infection-control policy, the prevalence of hospital-acquired infection (HAI) fell linearly from 10.5% in the second survey to 5.6% in the last. After the introduction of a specific urinary catheter care policy, the prevalence of hospital-acquired urinary tract infection (HAUTI) fell from 3.2% in the first four surveys to 2.0% in the last three. These differences persisted when the results were adjusted by logistic regression for patient risk factors, which varied between surveys: the declines for HAI and HAUTI were then 9.9% to 6.0% and 2.9% to 2.2% respectively. Infection control policies, therefore, can have substantial impact on the prevalence of HAI, and their effectiveness can readily be measured by repeated prevalence surveys.

Chi-Square Distribution↗
PubMed1989

A tuberculostearic acid assay in the diagnosis of sputum smear-negative pulmonary tuberculosis. A prospective study of bronchoscopic aspirate and lavage specimens.

OBJECTIVE: To determine whether the detection of tuberculostearic acid (TBSA) in bronchial aspirate and bronchoalveolar lavage specimens is useful for the rapid diagnosis of active pulmonary tuberculosis in patients suspected of having the disease. SETTING: A pulmonary clinic in a teaching hospital. PATIENTS: Forty patients suspected of active pulmonary tuberculosis but who failed to produce sputum or whose sputum smears were negative for acid-fast bacilli on at least 3 occasions, 29 of whom were subsequently confirmed to have tuberculosis. A group of 13 patients who were having fiberoptic bronchoscopy for other reasons served as controls. INTERVENTION: All patients had fiberoptic bronchoscopy; bronchial aspirate, bronchoalveolar lavage, and sputum specimens were obtained when possible. MEASUREMENTS AND MAIN RESULTS: All specimens were examined microscopically for acid-fast bacilli, cultured for mycobacteria, and assayed for TBSA by gas chromatography and mass spectrometry with selected ion monitoring. Only 4 of the 29 patients with tuberculosis were diagnosed by direct microscopy compared with 26 by TBSA assay. In 2 patients who required surgical biopsy for conventional diagnosis, the TBSA test was positive. There were no false-positive TBSA results in the 13 controls, but 2 of 5 sputum specimens from the 11 test patients in whom tuberculosis was excluded were falsely positive, probably because of contamination with mouth flora. Because sputum can rarely be obtained from these patients and may give false-positive results, it is not a good specimen for TBSA assay. Sensitivities and specificities of the test for the other specimens were as follows: aspirate, 0.52 (CI, 0.32 to 0.71) and 1.00 (CI, 0.75 to 1.00); lavage, 0.68 (CI, 0.46 to 0.85) and 1.00 (CI, 0.84 to 1.00); aspirate and lavage combined, 0.79 (CI, 0.60 to 0.92) and 1.00 (CI, 0.86 to 1.00). CONCLUSIONS: The TBSA assay for bronchial aspirate and bronchoalveolar lavage fluid is useful for rapidly diagnosing "smear-negative" pulmonary tuberculosis. In these specimens it is highly specific and more sensitive than microscopy. This assay could be used to diagnose other mycobacterial infections, however, it cannot distinguish among species.

Bronchoalveolar Lavage Fluid↗
PubMed1989

Special precautions reduce oropharyngeal contamination in bronchoalveolar lavage for bacteriologic studies.

Despite the use of quantitative culture, oropharyngeal contamination of bronchoalveolar lavage (BAL) specimens is still a factor that limits the usefulness of this technique in the diagnosis of lower respiratory tract infection. To investigate whether special precautions could reduce contamination, 20 noninfected patients undergoing diagnostic bronchoscopy were randomized into 2 groups of 10 patients: BAL was performed routinely in group R and with special precautions in group P. These precautions consisted of giving topical lidocaine by inhalation rather than by bolus injection, and passing the bronchoscope used for BAL through a previously inserted endotracheal tube. Quantitative culture of BAL specimens showed that 5 patients in group R (50%), but none of the patients in group P (0%), had at least 1 organism recovered in concentrations greater than or equal to 10(4) colony-forming units CFU/ml (p = 0.016). Fifteen of 39 isolates (38.5%) in group R and none of 18 isolates in group P (0%) were present in concentration greater than or equal to 10(4) CFU/ml (p = 0.001). We conclude that oropharyngeal contamination of BAL specimens can be minimized by adopting special precautions during the procedure and by using quantitative culture with 10(4) CFU/ml as the cut-off point. This may increase the specificity of the technique in the diagnosis of lower respiratory tract infection without reducing its sensitivity.

Bacteriological Techniques↗
PubMed1989

RNA-electrophoresis as a typing method for nosocomial rotavirus infection in a special-care baby unit.

During January and February 1988 an outbreak of nosocomial rotavirus infection occurred in a special-care baby unit (SCBU). Seven infants were affected, of whom five had symptoms of diarrhoea. Typing by RNA electrophoresis (electropherotyping) demonstrated that a single rotavirus strain was responsible for the outbreak. The epidemic electropherotype was introduced by an infant with diarrhoea admitted directly into the SCBU from the community. Eight other electropherotypes were identified during January and February in patients with community-acquired rotavirus diarrhoea on other paediatric wards, but the outbreak strain occurred only on the SCBU. Electropherotyping is a useful and rapid method for tracing the epidemiology of hospital-acquired rotavirus infection.

Communicable Disease Control↗
PubMed1989

Antimicrobial susceptibilities of Haemophilus species in Hong Kong.

Altogether 403 Haemophilus spp. were isolated in seven hospital laboratories in Hong Kong during June 1986, mostly from sputum. Of these 73% were Haemophilus influenzae and 27% Haemophilus parainfluenzae. All the isolates of H. influenzae were non-capsulated; Haemophilus spp. were not isolated from blood or cerebrospinal fluid (CSF) during the period of the study. Antimicrobial resistance, including multiple resistance, was common. Of all the strains of H. influenzae, 20% were resistant to 1 mg/l ampicillin, (all except one by production of TEM-1 beta-lactamase), 65% were resistant to 0.5 mg/l erythromycin, 25% to 1 mg/l tetracycline, 14% to 1 mg/l chloramphenicol (mediated by the production of a chloramphenicol-destroying enzyme) and less than 1% to 8 mg/l cefaclor and 0.5 mg/l trimethoprim. All isolates were susceptible to cephamandole and cefuroxime. Haemophilus parainfluenzae showed similar susceptibilities, except that a greater proportion of strains was sensitive to erythromycin and chloramphenicol. Only 50% of the ampicillin-resistant strains of H. influenzae and H. parainfluenzae contained detectable plasmids of 2-55 Mdal arranged in six to nine different plasmid profiles. Resistance to ampicillin and chloramphenicol has increased markedly in isolates of H. influenzae in Hong Kong over the last 5 years. This resistance may be associated with transposable genes.

Ampicillin↗