Bacterial constituents of indoor air in a high throughput building in the tropics.

Airborne bacteria are significant biotic constituents of bioaerosol. Bacteria at high concentrations in the air can compromise indoor air quality (IAQ) and result in many diseases. In tropical environments like Malaysia that extensively utilize air-conditioning systems, this is particularly significant due to continuous recirculation of indoor air and the potential implications for human health. Currently, there is a lack of knowledge regarding the impact of airborne bacteria on IAQ in Malaysia. This study was prompted by a need for reliable baseline data on airborne bacteria in the indoor environment of tropical equatorial Malaysia, that may be used as a reference for further investigations on the potential role played by airborne bacteria as an agent of disease in this region. It was further necessitated due to the threat of bioterrorism with the potentiality of release of exotic pathogenic microorganisms into indoor or outdoor air. Before scientists can detect the latter, a gauge of the common microorganisms in indoor (as well as outdoor) air needs to be ascertained, hence the expediency of this study. Bacterial counts from the broad-based and targeted study were generally in the order of 10(2) colony-forming units (CFU) per m(3) of air. The most prevalent airborne bacteria found in the broad-based study that encompassed all five levels of the building were Gram-positive cocci (67.73%), followed by Gram-positive rods (24.26%) and Gram-negative rods (7.10%). Gram-negative cocci were rarely detected (0.71%). Amongst the genera identified, Kytococcus sp., Micrococcus sp., Staphylococcus sp., Leifsonia sp., Bacillus sp. and Corynebacterium sp. predominated in indoor air. The most dominant bacterial species were Kytococcus sedentarius, Staphylococcus epidermidis and Micrococcus luteus. The opportunistic and nosocomial pathogen, Stenotrophomonas maltophilia was also discovered at a high percentage in the cafeteria. The bacteria isolated in this study have been increasingly documented to cause opportunistic infections in immuno-compromised patients, sometimes with fatal outcomes. Furthermore, some of them are becoming increasingly resistant to antibiotics. Hence, we propose that indoor reservoirs of these bacteria and their associated clinical and more subtle health effects, if any, be investigated further.

Characterization of cyst and trophozoite proteins of environmental isolates of Acanthamoeba castellanii by two-dimensional gel electrophoresis.

Acanthamoeba castellanii has been known to possess pathogenic properties, such as acanthamoebic keratitis and granulomatous amoebic encephalitis. The role of proteases and proteins in the pathogenesis of these infections is still poorly understood. As Acanthamoeba sp is a ubiquitous protozoon found in the natural environment they can potentially cause human infections. This study characterized cyst and trophozoite proteins of 3 environmental A. castellanii isolates in comparison with a clinical isolate, ATCC 50492. The latter and environmental IMU1 isolate had 100% genotype identity with A. castellanii and demonstrated protein spots with higher molecular weights (> 95 kDa) at relatively higher isoelectric values (> pI 7.00) compared to the two other environmental isolates (IMU4 and IMU5) that had 99% genotype identity to A. castellanii based on 16 S rDNA sequence. Thus such trophozoite proteins may be involved with the parasite's ability to cause acanthamoebic keratitis.

Toxoplasma gondii: determination of the onset of chronic infection in mice and the in vitro reactivation of brain cysts.

Toxoplasma gondii is an intra-cellular parasite that infects humans through vertical and horizontal transmission. The cysts remain dormant in the brain of infected humans and can reactivate in immunocompromised hosts resulting in acute toxoplasmic encephalitis which may be fatal. We determined the onset and progression of brain cysts generation in a mouse model following acute toxoplasmosis as well as the ability of brain cysts to reactivate in vitro. Male Balb/c mice, (uninfected control group, n = 10) were infected orally (study group, n = 50) with 1000 tachyzoites of T. gondii (ME49 strain) and euthanized at 1, 2, 4, 8 and 16 weeks post infection. Brain tissue was harvested, homogenized, stained and the number of brain cysts counted. Aliquots of brain homogenate with cysts were cultured in vitro with confluent Vero cells and the number of cysts and tachyzoites counted after 1 week. Brain cysts but not tachyzoites were detected at week 2 post infection and reached a plateau by week 4. In vitro Vero cells culture showed similar pattern for cysts and tachyzoites and reactivation of cyst in vitro was not influenced by the age of the brain cysts.

Efficacy and safety of chloroquine for treatment in patients with uncomplicated Plasmodium vivax infections in endemic countries.

Chloroquine (CQ) is a relatively inexpensive drug for treatment of malaria. If efficacy of CQ is still assumed, then it should be indicated in malaria treatment policies as the drug of choice for uncomplicated Plasmodium vivax malaria in endemic countries with resource constraints. The objective of this review is to summarize the existing evidence on the relative efficacy and safety of CQ in treating patients with uncomplicated P. vivax malaria in endemic countries. We searched online data bases (PUBMED, MEDLINE, EMBASE, The Cochrane Library) and the reference lists of the retrieved articles. Fifteen randomized controlled trials (n=6215) assessing the relative efficacy and safety of CQ for treatment of uncomplicated P. vivax malaria were included. CQ monotherapy was compared to CQ plus primaquine (PQ), artemisinin/artemether, artemisinin based combination therapy, quinine, CQ plus tafenoquine, chlorguanil plus dapsone, azithromycin, or placebo. Treatment efficacy was not significantly different between the CQ monotherapy group and that of the CQ with PQ 14 day group at 28 day follow-up (55/711, 7.7% vs 35/712, 4.9%; P=0.16). Evidence from the trials identified for this review draw a fairly clear conclusion about the relative efficacy and safety of CQ for treating uncomplicated P. vivax malaria infection. However, further research in this field with well powered, randomized, non-inferiority design, using the standardized protocol is needed.