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Biomedical subjects

E Houang

Publications and source records attributed to E Houang.

18 recordsLinked to original sources
PubMed1999

Isolation of Acinetobacter spp. including A. baumannii from vegetables: implications for hospital-acquired infections.

A. baumannii is rarely recovered from the skin of patients or healthy European subjects as other genospecies predominate, but it isa significant nosocomial pathogen. The natural reservoir of this organism is therefore uncertain. We determined the isolation rates of Acinetobacter spp. from vegetables (as an indicator of the natural environment) using a selective technique and classified the genospecies by amplified ribosomal DNA restriction analysis (ARDRA). Of the 177 samples of vegetables examined, 30 yielded Acinetobacter, with genospecies 2 and 11 being the most common, each with a frequency of 27%. MIC assays showed that strains of genospecies 1, 2, 3, and 13TU (the A. calcoaceticus-A. baumannii complex) were significantly more resistant than other genospecies to ciprofloxacin and gentamicin. Vegetables may therefore be a natural habitat of A. baumannii and provide a route by which these bacteria are introduced into hospitals with obvious implications for infection control.

Acinetobacter↗
PubMed1995

Pyrolysis mass spectrometry of cephalosporin-resistant Enterobacter cloacae.

Thirteen clinical and four environmental isolates of third-generation cephalosporin-resistant Enterobacter cloacae (CREC) together with single isolates from the hands of a nurse and from a blood gas analyser were associated with two clusters of nosocomial infection. With an unrelated CREC isolate they had been typed by serotype, biotype, ribotype and phage-type and were examined by pyrolysis mass spectrometry (PYMS) as described here. PYMS data yielded two clusters, major and minor. All except one isolate in the major cluster corresponded to type group identity (serotype 07, biotype 62, ribotype D) which had caused neonatal sepsis and colonization. Multivariate analysis showed a homogeneous group consisting of this strain plus two outliers. The minor cluster included four different strains, one of which, serotype 03, biotype 62, ribotype C had caused excoriation of the buttocks and colonization.

Cephalosporin Resistance↗
PubMed1994

Enterobacter cloacae in a neonatal intensive care unit: account of an outbreak and its relationship to use of third generation cephalosporins.

After uneventful use of cefotaxime and ceftazidime as first line therapy for three years in our neonatal intensive care unit we isolated cephalosporin-resistant Enterobacter cloacae (CREC) strains which caused clusters of cases or colonization and/or serious neonatal infection. By using two or more typing methods, at least five different strains with similar patterns of antimicrobial sensitivities were identified. The results of a case-control study did not support the notion that the use of third generation cephalosporins was associated with colonization and infection by CREC. The outbreak was brought under control by interrupting the transmission of the epidemic strain D, by measures such as cohort nursing, diligent handwashing before and after procedures, and thorough environmental cleaning as well as by decontamination with glutaraldehyde after dismantling of the blood gas analyser believed to have acted as a persistent reservoir. Our experience highlights the danger of inadequate supervision and maintenance of equipment used for near-patient testing and the need to monitor such equipment not only in terms of its calibration and analytical performance but also microbiologically.

Blood Gas Analysis↗
PubMed1991

Hospital green salads and the effects of washing them.

Each week from April 1989 to February 1990, a plate of green salad prepared in the hospital kitchen was examined microbiologically. Of the 256 plates examined, 51% had total viable counts (TVCs) of greater than or equal to 10(5) colony forming units (cfu) g-1. Staphylococcus aureus was present in 13 samples and Escherichia coli in one sample. No Listeria monocytogenes, Clostridium perfringens or Salmonella spp. were isolated. The effect of washing mustard and cress, cucumber and the different layers of lettuce leaves was examined. Washing the salad by agitating it under running tap water in a colander for 2 min reduced the total bacterial counts by 10-fold. The inner leaves of a lettuce had TVCs less than 10(4)cfu g-1, at least 10-100-fold less than the outer leaves. Cucumber after washing had similar TVCs as after peeling. Five of six samples of mustard and cress had TVCs of at least 10(6)cfu g-1 before washing. As a consequence, mustard and cress was no longer used in our salads.

Colony Count, Microbial↗
PubMed1991

Isolation of Listeria species from precooked chilled foods.

Cook-chill food prepared commercially was introduced to serve our patients and staff in 1989. The presence of Listeria monocytogenes in samples taken before regeneration was examined over two periods. For period A (April-November 1989), c. 0.2 g of food was examined; 2.7% of 992 meat samples and 0.6% of 1084 samples of other types of food were found to contain the organism. As a result, cold sliced meat was withdrawn from the patients' menu. For period B (February-July 1990), following the introduction of new guidelines, 25 g of food was examined after enrichment. Of the 854 meat samples examined 9% were positive for L. monocytogenes, and of the 1465 samples of other types of food examined 2.29% were positive. The significant increase between the two time periods occurred in the number of samples containing less than 10 colony forming units (cfu) g-1 of L. monocytogenes. The proportion of positive samples that contained 10-10(3) cfu g-1 remained the same for both periods (0.7%). Isolation of the organism was significantly associated with samples which had total viable counts of greater than 10(4) cfu g-1. There was no specific pattern of distribution of different serotypes in our isolates of L. monocytogenes. In the absence of evidence that small inocula of less than 10 cfu g-1 in cook-chill food before regeneration could be harmful to patients, we question whether the extra cost involved in following the Department of Health guidelines and examining 25 g of food for the presence of L. monocytogenes is justified.

Food Handling↗
PubMed1991

Comparison of two commercial kits for identifying and biotyping Haemophilus parainfluenzae.

The Minitek system and the more recently introduced Micro Scan HNID panels for the identification and biotyping of 98 V dependent Haemophilus isolates were compared. Identical results were obtained for 77 isolates. The discrepancy in the results of ornithine and urease was accounted for mainly by the mismatching of the identification by the two kits. When 13 isolates of H parainfluenzae with mismatched biotypes were re-examined, the results from Micro Scan correlated with 92% of those obtained by Christensen's urea broth and 100% by the ornithine test (Lab M); the corresponding figures for Minitek were 61% and 30%, respectively. Micro Scan was easy to handle on the bench and results were ready on the same day. These results suggest that further work is required to assess these two systems for the biotyping of H parainfluenzae.

Bacterial Typing Techniques↗
PubMed1990

A further look at infection at the time of therapeutic abortion.

Microbiological investigations and clinical follow-up were performed on 516 patients undergoing first-trimester termination of pregnancy, over a 2-year period. Chlamydia trachomatis was isolated by pre-operative microbiological screening in 6.7% of patients, gonococcus in 0.4% and Trichomonas vaginalis in 2%. Candida spp and Gardnerella vaginalis were isolated from 16% and 28% of the women, respectively. Patients who had positive cervical chlamydial isolation were significantly younger (less than 22 years) than those who did not. Doctor's clinical diagnosis of genital tract infection was found to be associated with a positive screening result but not with the likelihood of postabortal pelvic infection. Among the 175 patients followed up in the outpatient clinic, 4 of the 15 patients with a positive result for N. gonorrhoeae, C. trachomatis and/or T. vaginalis developed postoperative pelvic infection, which is significantly more than the group who did not harbour any of these three organisms (9/114).

Abortion, Therapeutic↗
PubMed1989

Comparison of genital and respiratory carriage of Haemophilus parainfluenzae in men.

In the first study, genital carriage of Haemophilus parainfluenzae was investigated in 103 women and 292 men attending a clinic for genitourinary medicine. In a second study, pairs of urethral and throat swabs were studied in 279 men. The vaginal carriage was 2%, urethral 12.4% and throat 13.3%. Biotype 2 was found to be a genital type and throat carriage of this biotype was significantly associated with its concomitant urethral carriage. Biotypes 1 and 3 were mainly found in the throat. Biotype 2 was significantly more likely to be resistant to ampicillin, tetracycline and sulphonamide but biotype 1 was significantly more likely to be resistant to trimethoprim.

Bacterial Typing Techniques↗
PubMed1987

Significant bacteremia associated with replacement of intrauterine contraceptive device.

Blood culture samples were taken from 23 women at different stages when an intrauterine contraceptive device was replaced. Transient bacteremia resulting from vaginal organisms was found in 13% of women 4 to 6 minutes after insertion of the new device. Previous reports have failed to demonstrate bacteremia associated with either first insertion or removal of intrauterine contraceptive device. Our results show that replacement of an intrauterine contraceptive device, a more traumatic procedure, causes significant bacteremia, and chemoprophylaxis should be given to patients in the groups at risk.

Female↗
PubMed1987

The midcycle cervical microbial flora as studied by the weighed-swab method, and its possible correlation with results of sperm cervical mucus penetration tests.

Infertile couples undergoing routine investigation for infertility were randomly selected for the study. A quantitative method using weighed swabs was found satisfactory for the study of microbial flora in the midcycle cervical mucus. In 6 of the 20 women, the midcycle cervical mucus was hostile in the sperm cervical mucus penetration tests. The total bacterial counts and the number of species (average, 2.5) isolated from the hostile mucus were significantly greater than those from the receptive mucus (average, 1.3). Only normal vaginal/cervical flora was isolated. Ureaplasma urealyticum was found more frequently in patients undergoing clomiphene citrate therapy (6/10 versus 0/9, P less than 0.03, Fischer's Exact test).

Cervix Mucus↗
PubMed1984

Trial of the use of masks in the gynaecological operating theatre.

A randomly controlled trial was performed on 41 women having gynaecological surgery in which the team of surgeons and nurses wore or did not wear masks. After major abdominal surgery, 3 of 5 patients in the unmasked group developed wound infections whereas no infection was observed in the 4 patients of the masked group. A greater number of Streptococci were also found by settle-plates on the operating table in the unmasked group. No infection was recorded after minor or vaginal surgery.

Abdomen↗
PubMed1980

10 Years of infective endocarditis at St. Bartholomew's Hospital: analysis of clinical features and treatment in relation to prognosis and mortality.

A retrospective survey of patients with infective endocarditis at St. Bartholomew's Hospital in the decade 1966--75 showed a male/female ratio of 1.5/1. The commonest presenting features were malaise, fever, new cardiac symptoms, heart-failure, splenomegaly, and finger clubbing. The commonest problem during treatment was heart-failure. As in the two previous decades, viridans streptococci were the commonest causative organisms. Acute endocarditis was caused by Staphylococcus aureus. 6 patients' lives were saved by heart-valve replacement during medical treatment. Of 3 patients who relapsed, 1 died. The overall mortality at six months was 20%, compared with 40% in the two previous decades. Of the patients with proven subacute infective endocarditis thought to have received adequate antibiotic treatment, only 5 of 49 (10%) died; in a similar group of patients in the previous decade 19% died. Early surgical intervention probably accounts for the improved prognosis.

Acute Disease↗
PubMedDate not supplied

Microbial keratitis in Hong Kong: relationship to climate, environment and contact-lens disinfection.

Microbial keratitis has been studied in Hong Kong as a representative sub-tropical climate of south China. An 18-month investigation in 1997/98 of 223 cases of ulcerative keratitis (presumed microbial) was conducted in the 2 million population of Shatin and Kowloon at the Prince of Wales and Hong Kong Eye Hospitals respectively with comprehensive microbiology. A case-control study was pursued at the same time between 45 contact-lens wearers (CLW) developing microbial keratitis and 135 lens-wearing volunteers matched for age, sex, educational status and visual acuity. Home water supplies were sampled for Acanthamoeba. Previous ocular surface disease and trauma (preventable by wearing goggles for grinding) were common predisposing causes while cosmetic wear of contact lenses was responsible for 26% of cases overall. Pseudomonas aeruginosa was the commonest bacterium isolated, from both CLW and non-CLW, with infection being acquired within the community. These 28 pseudomonads remained fully sensitive to the third-generation cephalosporins, aminoglycosides and quinolone antibiotics, which is very encouraging. Fungi were isolated, predominantly Fusarium sp., but less commonly than expected. A fungal/bacterial ratio was obtained of 1/17, while in comparison, the expected ratio for a tropical climate ranges from 1/5 (Singapore) to 1/2 (South India). Acanthamoeba was the second commonest microbe isolated from keratitis of CLW. The domestic water environment of 8% of homes of both patients and controls wearing contact lenses was colonized with Acanthamoeba. Lack of hygiene, use of tap water for storing lenses, failure to air-dry lens-storage cases or use of one-step hydrogen peroxide disinfectant were identified as risk factors for keratitis in CLW. The study results commend use of multipurpose solutions by CLW in Hong Kong to achieve the lowest expected rates of infection.

Acanthamoeba Keratitis↗