Development and evaluation of dot-immunobinding assay for detection of scrub typhus infection in Leptotrombidium fletcheri (Acari: Trombiculidae).

A dot-immunobinding assay (DIBA) was compared with a direct fluorescent antibody technique (DFAT) for the detection of Rickettsia tsutsugamushi infection in Leptotrombidium fletcheri (Womersley & Heaslip). Laboratory colonies of infected and noninfected chiggers were examined. The relative proportions of positive, negative, and indeterminate results were significantly different between DIBA and DFAT for infected but not for noninfected chiggers. DIBA was more sensitive and had a better negative predictive value and a lower false negative percentage than DFAT. It was concluded that DIBA is a suitable alternative to DFAT for detecting scrub typhus infection in chiggers.

Dynamic elastic constants of anisotropic materials by resonant ultrasound spectroscopy.

Resonant ultrasound spectroscopy (RUS) has been applied to the anisotropic elastic stiffness determination of SiC/Al composites and highly textured Zr-2.5 Nb alloys. To determine the elastic stiffness of anisotropic materials, the resonant frequencies of a rectangular parallelepiped specimen were measured and compared with the calculated frequencies based on the input data of the estimated stiffness, dimensions, and density. The initial estimates of the elastic stiffness of SiC/Al composites were calculated using the Mori-Tananka (MT) theory and the concept of effective aspect ratio of reinforcements. For highly textured Zr-2.5 Nb alloy, the initial estimates were obtained from its orientation distribution function, determined by X-ray diffraction, and the reported elastic stiffness of a single crystal zirconium. Through a comparison of calculated frequencies with those measured by RUS, elastic stiffness values have been determined very accurately by iteration and convergence processes.

Antimicrobial resistance pattern of bacteria isolated from patients seen by private practitioners in the Klang Valley.

Data on bacterial resistance in patients seen by general practitioners are usually not readily available. The objective of this paper is to present the antimicrobial resistance pattern of bacteria isolated from patients seen by private practitioners in the Klang Valley. A total of 18 clinics participated in this study. From mid August 1991 to end of June 1993, 2,823 specimens were received. Throat swabs and urine specimens constituted 56% of all the specimens. A large proportion of the specimens (55%) yielded no growth or just normal flora. The common bacteria encountered were Staphylococcus aureus (18.4%), Escherichia coli (16.2%), Klebsiella spp (13.7%) and Neisseria gonorrhoeae (9.3%). The S. aureus strains were mainly isolated from wound, pus and ear swabs. Not one out of the 218 strains tested was resistant to methicillin. In vitro susceptibility tests showed that 91% were resistant to penicillin while 23% were resistant to tetracycline and 13% to erythromycin. Eighty-two percent of the E. coli were isolated from urine. It was also the most common isolate from urine. Fifty percent of these strains were resistant to ampicillin, 33% to cotrimoxazole, 17% to cephalothin, 21% to ampicillin-sulbactam, 18% to amoxycillin-clavulanic acid while only 2.3% were resistant to nalidixic acid and nitrofurantoin and none to cefuroxime. Generally the gram negative bacilli encountered in general practice are less resistant to the third generation cephalosporins and aminoglycosides when compared to the hospital strains.

Atypical pneumonia due to Chlamydia pneumoniae: a case report.

A first case of Chlamydia pneumoniae pneumonia in Malaysia is reported. The diagnosis was made by a significant change in C. pneumoniae antibody titre. The infection responded well to a course of erythromycin.

Pattern of antibiotic usage in hospitals in Malaysia.

A prospective survey of antibiotic prescribing patterns in six Ministry of Health general hospitals in Malaysia was undertaken. Information on antibiotic prescriptions including the types of antibiotics used and the purposes for prescription was obtained through the use of questionnaires. A total of 1,918 antibiotic prescriptions were available for analysis. About two-thirds of prescriptions were for therapeutic purposes. The most common infections treated were lower respiratory infection (31%), followed by skin and soft tissue infection (17%), and urinary tract infection (8%). Only 20% of the therapeutic prescriptions were based on microbiological test results. Prophylactic prescriptions were issued for a variety of indications, the most common being toilet and suture of wounds. Only 5% of prophylactic prescriptions were of less than 3 days duration. There was great diversity in antibiotics and antibiotic regimens employed. It was evident that there was a lack of compliance with guidelines on antibiotic use issued by the Ministry of Health.

In vitro activity of cefoperazone-sulbactam: Singapore experience.

In vitro activity of commonly used antimicrobial agents against consecutively isolated 521 strains of Gram negative bacilli causing serious infections in the National University Hospital, Singapore were tested in parallel with cefoperazone-sulbactam combination. With the combination complete resistance of 2% and intermediate resistance of 5% were noted among the 521 strains tested. Resistance to imipenem was low (5%) but resistance against other antimicrobial agents varied from 12% (amikacin) to 80% (ampicillin). In vitro data demonstrated a possible future role for cefoperazone-sulbactam in the treatment of sepsis caused by Gram negative bacilli in our hospital.

Pulsed-field gel electrophoresis as an epidemiologic tool in the investigation of laboratory acquired Salmonella typhi infection.

Strains of Salmonella typhi implicated in two separate cases of laboratory acquired infection from patients and the medical laboratory technologists who processed the patients' samples were analysed by pulsed-field gel electrophoresis. Although all four isolates were of bacteriophage type E1, PFGE was able to demonstrate that the strains responsible for the two laboratory acquired cases were not genetically related. The PFGE patterns of the isolates from the MLTs were found to be identical to those of the corresponding patients after digestion with restriction enzyme AvrII. This provided genetic as well as epidemiological evidence for the source of the laboratory acquired infections.

The use of surgical antibiotic prophylaxis in seven Malaysian hospitals.

A survey on the use of antibiotics in surgical prophylaxis was carried out in seven Malaysian hospitals. Details of antibiotic prescriptions were obtained through questionnaires completed by the prescriber. A total of 430 such prescriptions was analysed. A large number of different antibiotic regimens were used for a variety of surgical procedures. The majority of prescriptions (70%) were issued for procedures where such prophylaxis was probably not necessary. Antibiotics were also often prescribed for durations that were longer than necessary. There is an urgent need to educate surgeons and standardize surgical prophylactic regimens in order to reduce cost and combat the emergence of antibiotic resistance.

In-vitro susceptibility of Pseudomonas pseudomallei isolated in Malaysia to some new cephalosporins and a quinolone.

The current drugs recommended for treatment of melioidosis are tetracycline, chloramphenicol and cotrimoxazole. Unfortunately these drugs are not the drug of choice in an acutely ill patient with septicaemia prior to the availability of laboratory results. With the discovery of the new cephalosporins which have a broad spectrum of activity clinicians are using them either alone or in combination with other antibiotics in such critical situations. Hence, an in-vitro study was carried out on the susceptibility of 41 strains of P. pseudomallei isolated in Malaysia, to these new cephalosporins and a new quinolone. The results showed that all the cephalosporins tested had some activity on the strains tested, with ceftazidime being the most active drug. Pefloxacin had very poor activity. However, further clinical studies are required to determine the duration, dosage and in-vivo activity of the antibiotics.

Development and preliminary evaluation of an IgM dot-immunobinding assay (IgM-DIA) for rapid serodiagnosis of scrub typhus infection.

An IgM dot-immunobinding assay (IgM-DIA) was developed for the diagnosis of scrub typhus infection. The whole cell antigens of Karp, Kato and Gilliam strains of Rickettsia tsutsugamushi were immobilized onto nitrocellulose paper and reacted with patients sera. The presence of IgM R. tsutsugamushi specific antibody in the patient sera could be detected by the observation of a visible brown dot on the nitrocellulose paper. The IgM-DIA has a sensitivity of 90.4% and specificity of 81.4% as compared to the indirect immunoperoxidase test. The IgM-DIA is rapid, simple, cost-effective, does not require microscope or incubator. It is recommended as a rapid screening test for the diagnosis of scrub typhus infection in the field or rural area within the hyperendemic region.

An evaluation of knowledge and awareness of disinfection and sterilization among health care workers.

Awareness of the disinfection and sterilization policy among hospital staff and their knowledge in basic principles and methods of disinfection and sterilization were studied before and after intervention using a self-administered questionnaire. Survey results showed that awareness (56.2%) before intervention was unsatisfactory. The nurses were more aware of the policy than other groups of medical personnel. Those unaware of the policy perform duties from memory or verbal instructions. A significant increase in awareness to 73.3% was observed after intervention (p < 0.05). Knowledge on methods of decontamination, disinfection and sterilization of equipment varies widely from 28.8% to 90.1%. 23.1% were unaware of the temperature used for sterilization while 72.4% did not know how containers of disinfectant should be refill. Only 14.7% knew the recommended method for washing containers. With education improvement was observed. The average knowledge improved from 44.4% to 57.3%. Our results indicated that continuous in-service education is needed to improve, supplement and update knowledge in this field after basic training. In addition orientation programs for new staff should also be aimed at creating awareness and providing information on guidelines and policies related to their duties.

Disinfection: gaps between recommended and actual practice.

Basic practices on disinfection was surveyed in 6 hospitals using an observation and interview checklist. Two surveys were done, one pre-(first survey) and one post-intervention (second survey). The disinfection and sterilization policy of the Ministry of Health was not available in 66 (70.2%) and 12 (13%) of the units in the first and second survey respectively. In the second survey, staff in all the units washed disinfectant containers before refilling compared with 41.5% of the units in the first survey. Dilution of disinfectants not recommended was found to be used in the first survey. Storing cleaned and sterile items in disinfectants, using disinfectant as a substitute for sterilization of autoclavable items and not decontaminating spillages were some of the wrong practices observed. Considerable improvements were made in the second survey. Improper usage of disinfectants was also indicated by failure of the in-use test. Rate of failure of disinfectants in-use decreased from 11.6% in the first survey to 5.0% in the second survey. To ensure proper disinfection practices, a comprehensive training program on disinfection is required for nurses and attendants.

Incidence of Listeria spp. in vegetables in Kuala Lumpur.

From April 1992 to September 1992, 280 samples of 10 different fresh vegetables, bought from four different market outlets in Kuala Lumpur were examined for the presence of Listeria spp. Most of the market produce were locally grown with the exception of carrots. The isolation procedure was based on the Food & Drug Administration method (modified) used for the detection of Listeria spp. Isolation media used were Listeria Selective medium and LiCl- phenylethanol-Moxalactam agars. The identification of isolates was by means of conventional biochemical tests and API Listeria identification system. Five out of the 280 samples showed Listeria contamination, Listeria monocytogenes was isolated in lettuce, sengkuang (Pachyrrhizus erosus) and selom Oenanthe javanica) and Listeria innocua was isolated from sengkuang (Pachyrrhizus erosus) and pegaga (Hydrocotyle asiatica).

Comparison of methods in the detection of enterotoxigenic Escherichia coli in a Malaysian laboratory.

The prevalence of Enterotoxigenic Escherichia coli (ETEC) in 433 stool samples from diarrhoeal cases of all ages was studied using two commercially available test kits for the detection of heat labile toxin (LT) and the infant mouse assay for the heat stable toxin (ST). 16 samples (3.7%) were positive for ETEC, of which nine were producing ST alone, six LT alone and only one was producing both LT and ST. Although the percentage of isolation rate was low, its occurrence was almost as common as the Shigella spp and Salmonella spp in the same study. Of the two test kits examined, the Phadebact ETEC-LT Test 50 (Pharmacia Diagnostics, Uppsala, Sweden) was found to be more suitable for use in a routine diagnostic laboratory. Ten out of 12 (83%) of the strains tested were resistant to one or more antibiotics.

A microbiological study of vaginal discharge in women attending a Malaysian gynaecological clinic.

Vaginal discharge is a common complaint of women attending gynaecological clinics. The purpose of this study was to compare the occurrence of commonly implicated microorganisms in vaginal discharge amongst women with or without the complaint, attending a gynaecological and family planning clinic. The association of Gardnerella vaginalis with bacterial vaginosis was also studied. It was found that there were no significant differences between the cases and controls in the isolation rate of Gardnerella vaginalis, Torulopsis glabrata, Ureaplasma urealyticum, Mycoplasma ssp and Group B streptococcus (p greater than 0.05). Only the isolation rate of Candida albicans was significantly higher in the cases than controls (p less than 0.01). However, there was a significant association of G. vaginalis with bacterial vaginosis.

Laboratory acquired murine typhus--a case report.

A 34-year-old laboratory worker developed murine typhus after an accidental splashing of Rickettsia typhi over her right eye and lips. Indirect immunoperoxidase test showed a four-fold increase in titre to Rickettsia typhi. She responded well to doxycycline.

In-vitro susceptibility of Burkholderia pseudomallei to cefoperazone-sulbactam combination.

Melioidosis is endemic in Malaysia. Emerging resistance with new and current antimicrobial agents has underscored the need to look further for new antimicrobial agents for the treatment of melioidosis. Hence, we evaluated the in-vitro susceptibility of fifty locally isolated strains of Burkholderia pseudomallei, the causative agent of melioidosis to cefoperazone-sulbactam combination using the method of NCCLS. All the fifty strains tested were susceptible in-vitro to cefoperazone-sulbactam. The MIC90 of the organism for cefoperazone-sulbactam was 4 mg/L. The results of our findings suggested that cefoperazone-sulbactam may be useful in the treatment of melioidosis.

Antimicrobial resistance in 6 Malaysian general hospitals.

Knowledge of local antimicrobial resistance patterns of bacteria is a valuable guide to empirical antimicrobial therapy. This paper reports the resistance patterns of more than 36,000 bacteria isolated between August 1991 and July 1992 in six Malaysian hospitals and discusses the implications of the results. A customized menu driven software programme was developed to analyse the results. Generally, resistance to the commonly used antibiotics like ampicillin, cloxacillin, cephalosporins, gentamicin, cotrimoxazole and tetracycline was high. Some differences in resistance rate amongst the six hospitals were also noted. Continuous surveillance of antimicrobial resistance in hospitals is encouraged for the effective control of the emergence of antimicrobial resistance.

5-Fluorocytosine resistance in clinical isolates of Cryptococcus neoformans.

Thirty six clinical isolates of Cryptococcus neoformans were tested for their susceptibility to 5-fluorocytosine and amphotericin B by the determination of minimum inhibitory concentrations and minimum fungicidal concentrations. 22.2% of the isolates were resistant to 5-fluorocytosine and 36.1% indicated 5-fluorocytosine tolerance. All strains were sensitive to amphotericin B.

A microbiological study of genital ulcers in Kuala Lumpur.

The microbial aetiology of genital ulcers was studied in 249 patients (241 men and 8 women) attending a Sexually Transmitted Disease Clinic in Kuala Lumpur, Malaysia. Herpes simplex virus type 2 was isolated in 48 (19.2%) patients, Haemophilus ducreyi from 22 (8.8%), Neisseria gonorrhoeae from seven (2.8%) and Chlamydia trachomatis from four (1.6%). Syphilis was diagnosed in 18 (7.2%) patients on the basis of dark field microscopy. Two (0.8%) patients were found to have both chancroid and syphilis and one (0.5%) had both gonorrhoea and syphilis. No organism was isolated in the remaining 151 (61.5%) patients. Overall, the accuracy of clinical diagnosis was 58% for single infection, 67% for herpes, 63% for syphilis, 47% for chancroid and 0% for lymphogranuloma venereum. Therefore, our study confirms the need for laboratory tests to diagnose accurately the aetiology of genital ulcer disease.