Diverse CTX phages among toxigenic Vibrio cholerae O1 and O139 strains isolated between 1994 and 2002 in an area where cholera is endemic in Bangladesh

PCR surveillance of the rstR genes of CTX phages in Vibrio cholerae O1 and O139 showed no relationship between the incidence of disease and changes in the rstR but showed variations in their presence in O1 and O139 strains and the occurrence of multiple types in a few strains.

Genetic relatedness of ciprofloxacin-resistant Shigella dysenteriae type 1 strains isolated in south Asia

OBJECTIVES

The aim of the present study was to determine the clonal relationships of ciprofloxacin-resistant Shigella dysenteriae type 1 strains isolated from south Asia, and S. dysenteriae 1 strains associated with epidemics in 1978, 1984 and 1994.

METHODS

The antimicrobial susceptibilities were examined by NCCLS methods. Molecular epidemiological characterization was performed by plasmid profiling, pulsed-field gel electrophoresis (PFGE) and mutation analysis of the quinolone resistance-determining region (QRDR) of gyrA by sequencing.

RESULTS

Plasmid patterns of the current ciprofloxacin-resistant strains from India, Nepal and Bangladesh were very similar to those of the 1978, 1984 and 1994 epidemic isolates of S. dysenteriae 1, except for the presence of a new plasmid of approximately 2.6 MDa, which was found in one recent ciprofloxacin-resistant strain isolated in Bangladesh. PFGE analysis showed that the ciprofloxacin-resistant strains isolated in Bangladesh, India and Nepal belonged to a PFGE type (type A), which was possibly related to that of the 1984 and 1994 clone of S. dysenteriae 1, but different from 1978 epidemic strains. The current ciprofloxacin-resistant strains belong to five subtypes (A3-A7), all of which were found in India, but in Bangladesh and Nepal, only A3 existed. Mutation analysis of the QRDR of gyrA revealed that amino acid substitutions at positions 83 and 87 of ciprofloxacin-resistant strains isolated in Bangladesh were similar to those of the strains isolated in Nepal, but different (at position 87) from ciprofloxacin-resistant strains isolated in India.

CONCLUSIONS

PFGE and mutation analysis of gyrA showed differences between the current ciprofloxacin-resistant S. dysenteriae 1 strains isolated in south Asia and those associated with epidemics in 1978, 1984 and 1994.

Biological screening of Bangladeshi mango mistletoe bark extracts

The ethyl acetate extract of the Bangladeshi mango mistletoe (Loranthus globosus) bark was found to be most effective against both Gram (+) and Gram (-) bacteria and it also showed good cytotoxicity with a LC50 10.83 microg/ml.

Emergence of methicilllin resistant Staphylococcus aureus (MRSA) associated with wound infections

In a hospital setting antimicrobial resistant organisms especially Methicillin resistant Staphylococcus aureus (MRSA) has emerged as an important variable influencing patients' outcome and overall resource utilisation. The present study was undertaken to find out the proportion of MRSA and other organisms and their antimicrobial resistance pattern in admitted cases with postoperative wound infections. A total of 50 wound swabs were collected irrespective of age and sex of the patients from National Institute of Traumatology and Orthopaedics Rehabilitation (NITOR). The laboratory work was performed in the department of microbiology of National Institute of Cardiovascular Diseases (NICVD). Isolation, identification and susceptibility testing was done according to the guideline of the National Committee for Clinical Laboratory Standards (NCCLS, 1998). Out of the 50 samples 34 yielded growths of which 15 had growth of single organism and 19 had mixed growth of 2 to 3 organisms. Four different types of organisms were identified. Highest percentage was Escherichia coli 55.9%, followed by Pseudomonas sp. 52.9%, Proteus sp. 38.2%, and Staphylococcus aureus 17.6%. Of the 6 isolates of S aureus 5 (83.3%) were MRSA. Therefore it can be concluded that MRSA is existing in the hospital premises of NITOR, which can endanger the life of many. This study emphasises that susceptibility testing of all clinical isolates is essential to reduce the morbidity, mortality and longer duration of hospital stay. In addition proper management of the cases can decrease the spread of multiple drug resistant organisms in the community.

Pattern of aerobic bacteria with their drug susceptibility of surgical inpatients

The pattern of aerobic bacteria with their antibiotic susceptibility isolated from infected patients in one of the surgical units at Mymensingh Medical College Hospital during the period from September to November' 2000 were reported in the present study. Out of 74 clinical samples, 52 were wound swabs, 18 were pus and 4 were urine. Bacterial growth was yielded in 43 samples and the distribution of isolates was as follows: Pseudomonas spp 16, Esch.coli 13, Staphylococcus aureus 08, Klebsiella spp. 03 and others 03. Majority (61.5 %) of culture positive results were found in wound swabs. Antibiotic susceptibility pattern showed considerable variation within Gram negative bacterial isolates. All the Esch.coli and Klebsiella isolates were resistant to amoxicillin. Ceftriaxone (65.6% and 100% respectively) and ciprofloxacin (71.4% and 100%) still appeared to be highly sensitive for both species. Over 93% strains of Pseudomonas were sensitive to Ceftazidime and aztreonam. Whereas, over 43% of same strains were resistant to ciprofloxacin. Over 87% strains of Staph.aureus were resistant to penicillin but sensitive to erythromycin. Whereas, 100% of those strains were sensitive to cloxacillin. Over 50% of all isolates were sensitive to gentamicin but resistant to cefalexin and cotrimoxazole. It was suggested to be careful regarding selection of antibiotic regime in surgical cases to minimize incoming higher magnitude of drug resistance among bacteria in near future.

Pattern of bacteria and their antimicrobial susceptibility isolated from inanimate objects and hospital personnel

Different inanimate samples collected from surgery wards and general operation theatre (GOT) as well as animate samples from surgery personnel were subjected to aerobic culture with the aim of identifying source of infections in surgical cases. The pattern of aerobic bacteria with antibiotic susceptibility isolated from those samples were reported in the present study. Out of 91 such samples, 53 and 26 were from different locations in general wards and OT respectively and 12 were comprising of hand swabs, throat swabs and nasal swabs from surgery personnel. Pathogenic bacteria were isolated from 34 samples having Pseudomonas spp. (18/34) in the top of the list followed by Esch. coli (14). Among the Esch.coli isolates resistance to cotrimoxazole, amoxicillin and doxycycline were 78.7%, 71.4% and 57.1% respectively, whereas sensitivity to aztreonam, ceftazidime, gentamicin and ciprofloxacin were 100%, 85.8%, 78.7% and 71.4% respectively. Ceftriaxone yielded intermediate sensitive results in 21.4% strains. Isolates of Pseudomonas spp. also showed very high sensitive results to aztreonam, ceftazidime and ceftriaxone (94.7%, 94.7% and 84.2% respectively). Ciprofloxacin and gentamicin were sensitive in 68.4% and 57.9% respectively. Susceptibility pattern showed well correlation with clinical response in infected cases.

Drug-resistant malaria in Bangladesh: an in vitro assessment

Forty-four Plasmodium falciparum isolates from Bangladesh and 22 from western Thailand were successfully tested for their drug susceptibility. High degrees of resistance were observed against chloroquine with geometric mean IC50s of 114.25 and 120.5 nM, respectively, for Bangladesh and western Thailand. Most isolates from both sites were sensitive to quinine, and all were sensitive to artesunate. Many isolates were considered in vitro resistant to mefloquine, but the geometric mean IC50 for the Thai isolates (98.79 nM) was 1.6 times (P = 0.002) higher than that of isolates from Bangladesh (60.3 nM). The high prevalence of in vitro mefloquine resistance in Bangladesh suggests that close surveillance is necessary to delay widespread multidrug resistant problems in the area.

A preliminary report on culture of Leishmania donovani in Mymensingh Medical College and evaluation of new immuno-chromatography test (ICT)

A total of 51 inpatients having prolonged low grade irregular fever with anaemia, hepatosplenomegaly, emaciation and other allied features were evaluated by findings of haematologic, seroimmunologic, microscopic examination for LD body and culture for L. donovani. The study was done during the period from September' 1999 to January' 2000. Bone marrow or splenic aspirates were examined for LD bodies and those samples were cultured in modified NNN media following a standard method. Out of 51 samples, 36 (70.5%) were positive for LD bodies in stained smears and 38 (74.5%) were positive in culture. The mean time of culture positivity was 5 +/- 2 days. Specific antileishmanial antibody were detected by Immunochromatography Test (ICT) in all 38 confirmed cases, whereas Aldehyde test (AT) were negative in 3 such cases. ICT was positive in 1 and AT in 7 cases where no parasite could be detected. So, sensitivity of ICT was 100% with a specificity of 92.3% and sensitivity of AT was 92.1% with a specificity of 46.1%.

Increasing trend of ciprofloxacin resistance amongst common bacterial isolates at Mymensingh Medical College and Hospital

Ciprofloxacin resistance among common bacterial pathogen comprising Esch.coli, Staph.aureus and Pseudomonas spp. isolated from different clinical samples of Mymensingh Medical College Hospital during the periods of September, 1999 to March, 2001 and September, 2001 to August, 2002 were recorded. Values of two periods were compared and increased rate of ciprofloxacin resistance were noted in every bacterial species, e.g. 32.0% in Esch.coli, 8.7% in Staph.aureus and 5.1% in Pseudomonas spp. It was suggested to be aware and careful regarding use of ciprofloxacin in clinical practice so as to limit emergence of bacterial strains resistance towards the drug.

Effects of cervical traction and exercise therapy in cervical spondylosis

A randomised clinical trial was conducted in the Department of Physical Medicine, Chittagong Medical College Hospital from July, 2001 to June, 2002. The objectives of the study were to find out the effects of cervical traction (CT) and exercise on the patients with chronic cervical spondylosis. A total of 199 patients with cervical spondylosis were included in the clinical trial. One hundred patients were treated with cervical traction plus exercise and 99 patients were treated with non-steroidal anti-inflammatory drug (NSAID). Posture correction advice was given to all patients. The patients were treated for 6 weeks. There was a marked improvement in both the groups after treatment (P<0.001). But there was nearly significant difference regarding improvement in treatment with CT plus exercise than with NSAID (P = 0.06). The results indicate that the improvement of the patients with chronic cervical spondylosis was more in CT plus exercise than analgesics. So, CT & neck muscle strengthening exercise may have some more beneficial effects than NSAIDs on chronic cervical spondylosis.

Effects of fluconazole singly and in combination with 5-fluorocytosine or amphotericin B in the treatment of cryptococcal meningoencephalitis in an intracranial murine model

In this study we developed a highly reproducible intracranial murine model of cryptococcosis. Mice (Balb/c, 5-7 weeks old) were challenged intracranially and treated with intermediate (30 mg/kg) or high (90 mg/kg) dose fluconazole, and amphotericin B (0.75 mg/kg), administered singly or in combination with flucytosine (100 mg/kg). Survival and brain CFU analyses were performed. Effect of fluconazole prophylaxis was also determined. Our data show that the developed model mimics clinical signs of cryptococcal meningitis. In single treatment, fluconazole (30 mg/kg) was more efficacious than amphotericin B or flucytosine (P < 0.0001). Combination treatment led to significantly increased anticryptococcal activity, which was highest for high dose fluconazole + flucytosine (P < 0.0001). However, no significant difference was observed between high dose fluconazole treatment with and without flucytosine (P >0.05). Fluconazole prophylaxis led to a significant decrease in brain CFU. In conclusion, high dose fluconazole administered post-infection, or as prophylaxis, may be highly efficacious in the treatment and prevention of meningoencephalitis.

Lipid formulations of polyene antifungal drugs and attenuation of associated nephrotoxicity

Amphotericin B is an effective broad-spectrum antifungal agent, but various side effects, especially nephrotoxicity, have restricted its use. Recently, lipid formulations of amphotericin B have been developed in order to reduce its toxic side effects. Clinical trials, although in the early stages, suggest promising results, and that some of these lipid formulations are potent and less toxic, even at higher doses. We summarize herein the existing information about newer lipid formulations of polyene antifungal drugs, which could attenuate associated nephrotoxicity.

Microarray analysis of differential gene expression in lead-exposed astrocytes

The toxic metal lead is a widespread environmental health hazard that can adversely affect human health. In an effort to better understand the cellular and molecular consequences of lead exposure, we have employed cDNA microarrays to analyze the effects of acute lead exposure on large-scale gene expression patterns in immortalized rat astrocytes. Our studies identified many genes previously reported to be differentially regulated by lead exposure. Additionally, we have identified novel putative targets of lead-mediated toxicity, including members of the family of calcium/phospholipid binding annexins, the angiogenesis-inducing thrombospondins, collagens, and tRNA synthetases. We demonstrate the ability to distinguish lead-exposed samples from control or sodium samples solely on the basis of large-scale gene expression patterns using two complementary clustering methods. We have confirmed the altered expression of candidate genes and their encoded proteins by RT-PCR and Western blotting, respectively. Finally, we show that the calcium-dependent phospholipid binding protein annexin A5, initially identified as a differentially regulated gene by our microarray analysis, is directly bound and activated by nanomolar concentrations of lead. We conclude that microarray technology is an effective tool for the identification of lead-induced patterns of gene expression and molecular targets of lead.

Survival of Shigella dysenteriae type 1 on fomites

Studies have shown that various objects, such as utensils, toys, and clothes, can serve as vehicles for transmission of Shigella spp. Shigellae can become viable but non-culturable (VBNC) when exposed to various environmental conditions as shown in earlier studies. The present study was carried out to detect VBNC Shigella dysenteriae type 1 on various fomites by direct viable counting, polymerase chain reaction (PCR), and fluorescent antibody methods. S. dysenteriae type 1 was inoculated onto cloth, wood, plastic, aluminum, and glass objects. Results showed that 1.5-4.0 hours after inoculation, S. dysenteriae type 1 became non-culturable, and after five days, non-culturable but viable S. dysenteriae type 1 could be detected by both PCR and fluorescent antibody techniques. Fomites can be considered an important potential route of transmission of VBNC S. dysenteriae type 1 and a significant factor in the epidemiology of shigellosis.

New developments in chemotherapy for non-invasive fungal infections

Dermatomycosis and subcutaneous mycosis comprise the non-invasive fungal infections commonly encountered in clinical practice around the world. The limited activity of early topical antifungal agents prompted the development of more effective systemic agents. While griseofulvin has been used for more than four decades, the use of early azoles, such as ketoconazole have resulted in better patient compliance and thus greater success. However, poor response and recurrence in dermatomycosis, as well as toxicity associated with ketoconazole therapy, has led to the search for newer antifungal agents and more effective treatment strategies. Terbinafine, itraconazole and fluconazole have the advantage of non-toxicity and a broad spectrum of activity. An overview of non-invasive fungal infections, antifungal agents in clinical use and recent developments in antifungal therapy is reviewed in this article.

G1 antigen: a cell-surface immunoprotective 96 kDa glycoprotein from the virulent fish pathogen Enterococcus seriolicida, its purification and characterization

Strains of the fish pathogen Enterococcus seriolicida were identified as agglutinating and non-agglutinating, according to their reaction with anti-serum raised against type strain YT-3 (ATCC49156). The non-agglutinating strains are highly pathogenic in contrast to agglutinating strains. A 96 kDa immunoprotective glycoprotein G1 antigen from non-agglutinating Ent. seriolicida strain SS91-014 (N) was purified and characterized. The purification procedure entailed extraction of antigen by glass bead agitation, 80% (NH4)(2)SO4 precipitation, gel filtration and electroelution. An immunofluorescence microscopy study using monoclonal antibody M3A5 raised against G1 antigen revealed that G1 antigen is present only on the cell surface of non-agglutinating strains. Therefore, the G1 antigen of virulent Ent. seriolicida could be a potential candidate for protective vaccine against enterococcosis in fish.

A randomized controlled trial comparing artemether and quinine in the treatment of cerebral malaria in Bangladesh

A randomized controlled trial on 51 patients receiving artemether and 54 patients receiving quinine was undertaken to compare the effectiveness of intramuscular artemether and parenteral quinine in the treatment of cerebral malaria in adults in Bangladesh. Case fatality, fever and parasite clearance times were not significantly different in the two treatment groups. Coma resolution time was significantly delayed in artemether recipients. Results of the study suggest that treatment with artemether is as effective as parenteral quinine in the treatment of cerebral malaria in adults.