Isolation of Acanthamoeba sp. from conjunctival sac of healthy individuals using swab

Is Acanthamoeba sp. normally found in the eyes? A study was carried out to establish the possibility of Acanthamoeba sp. as a part of the normal conjunctival flora. Conjunctiva swabbing were carried out in 286 healthy Orang Asli school children using sterile cotton swab. The swab was then inoculated onto non-nutrient agar (NN-A). Heat killed Escherichia coli that was used as food source for the growth of the amoebae was pipetted onto and away from the smear. The plates were incubated at 30 degrees C and examined daily using an inverted microscope for 14 days. Morphology of the trophozoites and cysts of the amoebae were used as the taxonomic criteria for identification. Positive-controls and negative-controls were done to check for the consistency of the technique used and monitoring of contamination respectively. None of the conjunctiva swab cultured was positive for Acanthamoeba sp. This finding may indicate that Acanthamoeba sp. is not part of normal conjunctival flora or conjunctiva swab is an insensitive technique to isolate the organism. However, a more extensive research is needed to investigate these possibilities.

Staphylococcus aureus carriage in selected communities and their antibiotic susceptibility patterns

The carriage and antibiotic susceptibility patterns of Staphylococcus aureus in the community were determined. Nasal, throat and axillary swabs were taken from 100 healthy adults and 90 disabled nursing home inmates. Antibiotic disc susceptibility testing was conducted following the NCCLS method. Staphylococcus aureus carriage was noted in 29% of healthy adults and 47.7% of nursing home inmates. Out of 79 strains, resistance to antibiotics were as follows; penicillin (92.4%), genetamicin (2.5%), tetracycline (6.3%), fusidic acid (11.3%), erythromycin (3.8%), pefloxacin (5.1%), mupirocin (3.8%), amikacin (3.8%), ciprofloxacin (2.5%) and chloramphenicol (2.5%). Methicillin-resistant Staphylococcus aureus was not isolated. Multiple colonizations and multi-antibiotic resistant Staphylococcus aureus were shown to occur in healthy individuals without risk factors and not previously hospitalized.

Detection of Vibrio cholerae 01 from aquatic environment in Sarawak

The detection of Vibrio cholerae 01 from the aquatic environment of Daro and Bintulu in Sarawak was carried out following an outbreak of cholera. Conventional culture methods and detection of ctx gene by polymerase chain reaction technique were carried out on 80 water samples. Only one sample was positive by culture methods while 8 were positive by PCR. DNA finger printing by pulsed-field gel electrophoresis showed that the clinical isolates in Daro and Bintulu were genetically identical while the environmental isolate was closely related. Recovery of Vibrio cholerae by culture method is poor and newer methods of detection should be developed.

DNA fingerprinting of methicillin-resistant Staphylococcus aureus by pulsed-field gel electrophoresis (PFGE): comparison of strains from 2 Malaysian hospitals

AIM OF STUDY

To determine and compare the pulsed-field gel electrophoresis (PFGE) patterns of endemic MRSA strains in 2 major Malaysian hospitals and to compare the PFGE patterns with antibiotypes of the strains studied.

METHODS

Fifty-six MRSA strains selected randomly between September 1997 and July 1998 from Hospital Queen Elizabeth (HQE) and Hospital Umum Sarawak (HUS) were tested for antimicrobial resistance and DNA fingerprinting was carried out by pulsed-field gel electrophoresis (PFGE) technique.

RESULTS

Seven PFGE types were recognised (A, B, C, D, E and F). All 7 PFGE types were observed in HQE while only 2 PFGE types (B, C) were noted in HUS strains. There is a predominance of a single PFGE pattern (type B) in both hospitals, as seen in 46% of HQE strains and 89% of HUS strains. Subtype B2 was the commonest subtype in HQE while subtype B1 predominated in HUS. Strains resistant to fusidic acid and rifampicin exhibited PFGE type F that is unique to HQE. All strains were resistant to penicillin, erythromycin, cotrimoxazole, tetracycline and gentamicin. Strains with the same antibiotic susceptibility pattern can be different PFGE types.

CONCLUSION

Molecular typing of the MRSA by PFGE is a useful tool in the study of endemic strains present in an institution. Strains in HQE were found to be more heterogeneous than HUS strains. Common PFGE types can also be seen in both hospitals suggesting that some of the strains was genetically related and has propagated within and between the 2 hospitals. Our findings also indicate that the relationship between antibiotic susceptibility and PFGE patterns was not close and antibiograms should not be relied upon for typing strains in epidemiological studies. By knowing the DNA fingerprints of the isolates endemic in each hospital, the spread of MRSA with a particular PFGE type can be monitored within and between hospitals.

Enteropathogenic Escherichia coli in raw and cooked food

A total of 402 Escherichia coli isolates were obtained from a variety of food samples and screened for enteropathogenic E. coli (EPEC). Screening was carried out using 15 specific monovalent antisera from Murex Diagnostic Limited. A total of 19 E. coli isolates were serotyped as EPEC. The EPEC strains were shown to belong to 8 serotypes. Eight out of 19 EPEC strains belonged to serotype 018C:K77 (B21). Seventeen out of 19 of the EPEC strains were isolated from cooked food. The presence of E. coli in cooked food is an indicator of fecal contamination and a sign of unhygienic food handling. The presence of EPEC in food could be a potential source of food-borne outbreak. Hygiene training for every food-handler is a necessity.

Indirect hemagglutination antibodies against Burkholderia pseudomallei in normal blood donors and suspected cases of melioidosis in Malaysia

Interpretation of the indirect hemagglutination test (IHA) for melioidosis in endemic areas is difficult because of the presence of antibodies in apparently healthy individuals. Fifty-three out of 200 healthy blood donors in Malaysia showed positive antibody titers (> or = 1 : 40) against Burkholderia pseudomallei. Seven percent had an IHA titer of 1 : 40, 11% had an IHA titer of 1 : 80 while 8.5% had a titer > or = 1 : 160. Out of 258 sera sent for melioidosis serology, 7% of the patients had an IHA titer of 1 : 40, 9% had an IHA titer of 1 : 80 while 20% had an IHA titer of > or = 1 : 160. If a titer of > or = 1 : 80 is taken as cut off point for positivity, 29% of the patients had positive melioidosis serology. Increasing the positivity threshold may jeopardize the sensitivity of the test. A more specific and sensitive test is needed.

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.

Cryptosporidiosis among HIV positive intravenous drug users in Malaysia

A study conducted at the Tampin Drug Rehabilitation Center in Malaysia established a high prevalence (23%) of asymptomatic carriers of Cryptosporidium among exposed HIV positive intravenous drug users (IVDUs). A majority of them were young adults and among the ethnic groups, the Malay HIV positive inmates had the highest prevalence of Cryptosporidium infection.