The Disinfecting Potential of Contact Lens Soutions used by Sultan Qaboos University Students.

OBJECTIVES: This study aimed to determine the disinfecting potential of some contact lens solutions used by some university students in Oman. METHODS: This work was carried out from January to June 2010 in the Department of Microbiology & Immunology, College of Medicine and Health Sciences, Sultan Qaboos University, Oman. Fifty disinfecting solutions, in which contact lenses were disinfected according to the manufacturers' instructions, were collected from the students and plated on various microbiological culture media. Bacterial isolates were identified by API-20E, API-20NE and Phoenix automated systems while fungi were identified by their cultural characteristics and biochemistry. RESULTS: From 98 isolates, Pseudomonas aeruginosa was 23.5%; Penicillium, 13%; Candida species, 9.2%; coagulase negative staphylococci, 9.2%; Serratia marcescens, 6.1%; Bacillus, 5.1%; Aspergillus flavus, 5.1%; Serratia liquefaciens, Pseudomonas fluorescens, Enterobacter cloacae and Aspergillus niger, 4.1% each; Chryseomonas luteola and Chryseomonas indologenes, 3.1% each; Stenotrophomonas maltophilia, Serratia odorifera, 2.0% each; Enterobacter aerogenes and Klebsiella pneumoniae, 1% each. Most isolates (65%) came from polyhexanide containing solutions. CONCLUSION: Contact lens disinfecting solutions with the same formulations, but manufactured by different companies, possessed different disinfecting potentials.

Nature of bacteria found on some wards in Sultan Qaboos University Hospital, Oman.

This study aims to determine what objects lying in the hospital environment or brought in from outside contribute to the introduction of bacteria associated with nosocomial infections. One hundred swab specimens collected from children's toys, sinks, door handles, telephone handsets and flowers brought into the hospital were plated on different culture media. Colonial growth on the media was purified and identified subsequently using standard bacteriological methods. Of the 100 samples cultured, 61 (61%) grew a range of bacteria including Pseudomonas aeruginosa (n=14, 23.0%), Acinetobacter spp. (n=13, 21.3%), Serratia spp. (n=9, 14.7%), Staphylococcus epidermidis (n=9, 14.7%), Stenotrophomonas maltophilia (n=4, 6.6%), Staphylococcus aureus (n=4, 6.6%), Enterobacter cloacae (n=3, 4.9%), Pantoea sp. (n=2, 3.3%), Chryseobacterium sp. (n=2, 3.3%) and Klebsiella pneumoniae (n=1, 1.6%). Although all the Serratia, Enterobacter, Klebsiella and Pantoea species isolates showed varying degrees of resistance to gentamicin, ceftriaxone, cefuroxime and cefotaxime, all were resistant to ampicillin. Chryseobacterium and Stenotrophomonas species isolates were resistant to amikacin, imipenem, gentamicin and ceftazidime, to which only three isolates of Pseudomonas species were resistant. All the staphylococcal isolates were susceptible to methicillin. Although there has been no major outbreak of a nosocomial infection in the hospital, it is strongly recommended that effective control measures (e.g., sampling the hospital water supply, disinfecting children's toys, use of appropriate hand washing and checking some of the disinfectants for presence of bacteria) are needed. These measures are necessary to ensure that the antibiotic-resistant strains identified in this study are not allowed to spread in the hospital.

Antimicrobial activities of clove and thyme extracts.

OBJECTIVE: It has been postulated that geographical locations of the herbs affect the constituents of their essential oils and thus the degree of their antimicrobial action. This study examine two samples of clove obtained from Sri Lanka and Zanzibar and two samples of thyme from Iran and Oman to determine the antimicrobial potential of their extracted oils. METHOD: The active agents in each plant were extracted by steam distillation and by boiling. The antimicrobial activities of the extracts were determined at neat and by two-fold dilutions in well agar diffusion technique using Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pyogenes, Corynebacterium species, Salmonella species, Bacteroides fragilis and Candida albicans. RESULTS: All oil extracts possessed antimicrobial activity against all bacteria and yeast tested. Their water extracts exhibited lower antimicrobial activity, though thyme aqueous extract was active only against S. aureus. The lowest concentration of antimicrobial activity (0.1% i.e., 1:1024) was obtained with thyme oil extract using Candida albicans. There was no significant difference in antimicrobial activity between clove obtained from Sri Lanka or Zanzibar or thyme obtained from Iran or Oman. CONCLUSION: Our experiment showed that the country of origin of the herbs has no effect on their antimicrobial activity. However, further work is necessary to ascertain why Candida albicans displayed remarkable degree of sensitivity with the extracts than all the other organisms test.

Evaluation of the neutralising capacity of bactec medium for some antibiotics.

Bactec medium 9240 (Becton Dickinson, MD, USA) is a blood culture medium used routinely at Sultan Qaboos University Hospital (SQUH). The medium is said to contain substances that can neutralise antibiotics and destroy leucocytes in blood samples. In this study, the ability of the medium to neutralise the effect of some antibiotics and to destroy leucocytes is investigated. Vancomycin, amoxicillin, chloramphenicol, penicillin, gentamicin, fungizone and amikacin at various concentrations were added to separate bottles of Bactec medium 9240. Escherichia coli (NCTC 10418), Pseudomonas aeruginosa (NCTC 10662), Staphylococcus aureus (NCTC 6571) and Candida albicans (ATCC 10231), each at 1 x 10(4) colony-forming units (CFU)/mL were added separately, depending on the type of antibiotic. The blood samples were incubated at 37 degrees C for seven days under manual and automated blood culture systems. Subcultures were made from the manual system and routine laboratory procedures for detection of positive cultures were followed for the automated system. The Bactec medium was found to neutralise all antibiotics up to a concentration of 100 microg/mL by the automated method but showed some variation in results by the manual system. Leucocytes were destroyed within 24 hours.

In vitro antibacterial activity of Omani and African honey.

The study aims to investigate the antibacterial activity of honey obtained from different parts of Oman and compare it with that of honey obtained from elsewhere in Africa. A total of 24 honey samples (16 from different parts of Oman and eight from elsewhere in Africa) were investigated for their antibacterial activity against Staphylococcus aureus (NCTC 6571), Escherichia coli (NCTC 10418) and Pseudomonas aeruginosa (NCTC 10662) using standard antimicrobial assays. Marked variations in the antibacterial activity of the different honey samples were observed. Fourteen of the 16 Omani samples and five of the eight African samples showed antibacterial activity ranked as either fair, good or excellent to at least one of the three bacterial strains tested. Both Omani and African honeys possess in vitro antibacterial activity against the three bacterial strains tested, with 25% of the samples showing excellent antibacterial activity.

Seasonal prevalence of protozoan parasites in Nsukka, Nigeria.

Five hundred fresh stool specimens of patients with clinical symptoms of protozoan infections were examined for parasites. During June 1988-May 1991, the total number of positive cases was 261 (52.2 per cent). When the infectivity frequencies were segregated among the samples of different localities, it was observed that 6 (1.2 per cent) persons from the University of Nigeria community, 89 (17.8 per cent) urban dwellers and 166 (33.2 per cent) rural populace were infected. The highest incidence of Giardia lamblia (83, 47.8 per cent), Entamoeba histolytica (49, 28.3 per cent) and Chilomastix mesnili (34, 19.7 per cent) was found among the rural community. The infection started in April of each year (onset of rainy season), peaked between July and August, and was the lowest between November and March (dry season). Statistical interpretation of the results indicated that the parasitic infections depended on times of the year x2 0.01 > 4 calculated x2 0.01, 0.05 > 4 tabulated. The vehicle of transmission of the infection was green vegetable (Amaranthus viridans) which gets polluted by sewage oxidation pond at the locality.

Cultural conditions for Aeromonas hydrophila affect the production of haemolysins with differing host specificities.

Five strains of Aeromonas hydrophila were studied for production of haemolysin specific for erythrocytes of various animal species using three cultural methods. All the strains produced haemolysin for all the erythrocyte species when the organisms were cultured on blood agar. Using cellophane overlay method, all the strains produced haemolysin for fish erythrocytes and variable activity to mammalian erythrocytes. Only one strain produced haemolytic activity for various though not all of the erythrocyte species when grown in brain heart infusion broth. Data suggest that A. hydrophila produces multiple haemolysins with specificities for erythrocytes of different animals. This was confirmed for trout and horse erythrocyte targeted haemolysins, by using iso-electric focussing separation and by measuring the effect of addition of ammonium sulphate to the growth medium.

Salmonella, arizona, Shigella and Aeromonas isolated from the snail Achatina achatina in Nigeria.

The Salmonella, Arizona, Shigella and Aeromonas contents of 39 snails (Achatina achatina) were investigated. Serotyping of the Salmonella isolates revealed the presence of S. manhattan, S. ndolo, S. reading, S. uppsala, and S. typhimurium. Six of 18 Shigella isolates were identified as Sh. sonnei while all the Aeromonas proved to be A. hydrophila. Fifty eight percent of these A. hydrophila isolates were enterotoxigenic, and their toxin was shown to be heat labile. All the A. hydrophila strains were both protease positive and haemolytic: 66.7% being both alpha and beta haemolytic while 33.3% showed only alpha haemolysis.