Transition of drug susceptibilities of Vibrio cholerae O1 in Lao People's Democratic Republic

The changes of drug susceptibilities of Vibrio cholerae O1 isolated during the past 7 years (1993-1999) in Lao PDR were investigated. The most noteworthy finding was the appearance of polymyxin B sensitive El Tor vibrios. Until 1996, the susceptibilities were almost as expected and cholera disappeared in 1997. When a cholera outbreak resurfaced in 1998, the susceptibilities of isolated V. cholerae O1 against tetracycline, sulfamethoxazol-trimethoprim, chloramphenicol and polymyxin B were quite different from those of previously isolated organisms. Minimum inhibitory concentrations (MICs) of tetracycline and chloramphenicol against the isolates in 1998 were about 16 times higher than those against the previous isolates, and the MICs of sulfamethoxazol-trimethoprim were about 256 times higher than those against the previous isolates, (trimethoprim 32 microg/ml: sulfamethoxazol 608 microg/ml). Eleven percent of the isolates (11/99) were as sensitive to polymyxin B as the classic cholera vibrios (MIC < 2 microg/ml). In 1999, the susceptibility pattern was almost the same as that in 1998 except for polymyxin B to which 58% of the isolates (21/36) became sensitive.     

An outbreak of allergy-like food poisoning

Eight cases of allergy-like food poisoning resulting from the ingestion of yellowfin tuna, which had been kept in stock for 10 days prior to being cooked, are described. The main symptoms were headaches, facial flushing and palpitation. Samples of the ingested fish were analyzed for histamine content, and a high level of histamine was confirmed (310 mg/100 g of fish). Corticosteroids were given to 3 patients who exhibited dyspnea or persistent symptoms, while the remaining patients improved without medication. In situations where allergy-like clinical features are present after the ingestion of food, the possibility of allergy-like food poisoning should be recognized and included in a differential diagnosis.     

Portal and mesenteric vein and inferior vena cava thrombosis associated with antiphospholipid syndrome

We report a 48-year-old man with thrombosis of the portal and superior mesenteric vein and inferior vena cava associated with primary antiphospholipid syndrome (APS). Primary APS was diagnosed by a positive reaction with anticardiolipin antibody (aCL) and the absence of any evidence suggesting the presence of other disease states known to be associated with aCL. A coeliac angiography showed obstruction of the portal and superior mesenteric vein with prominent collaterals and cavernous transformation. Femoral vein angiography showed total obstruction of the external iliac vein and inferior vena cava, and dilation of the pelvic veins, with contrast medium in the lumbar vein. This case is noteworthy as a report of primary APS accompanied by extensive abdominal and pelvic venous thrombosis.     

Short report: isolation of Escherichia coli O157:H7 from fecal samples of cows in Vietnam

Enterohemorrhagic Escherichia coli O157:H7 was isolated for the first time in Vietnam. Shiga toxin-producing E. coli were isolated from 8 of 100 cows examined. The two strains showing serotype O157:H7 carried the eae, ehxA, and stx2c genes, but the other six were negative for the eae gene.     

Increased nitric oxide production and gender-dependent changes in PPARα expression and signaling in the fetal lung from diabetic rats

The fetal lung is affected by maternal diabetes. Nuclear receptor PPARα regulates nitric oxide (NO) overproduction in different tissues. We aimed to determine whether fetal lung PPARα expression is altered by maternal diabetes, and if there are gender-dependent changes in PPARα regulation of NO production in the fetal lung. Fetal lungs from control and diabetic rats were explanted on day 21 of gestation and evaluated for PPARα expression and NO production. Fetuses were injected with the PPARα ligand LTB(4) on days 19, 20 and 21, and the fetal lung explanted on day 21 to evaluate PPARα and the inducible isoform of NO synthase (iNOS). Besides, pregnant rats were fed with olive oil- and safflower oil-supplemented diets, enriched in PPAR ligands, for evaluation of fetal lung NO production and PPARα expression. We found reduced PPARα concentrations only in the lung from male fetuses from the diabetic group when compared to controls, although maternal diabetes led to NO overproduction in both male and female fetal lungs. Fetal activation of PPARα led to changes in lung PPARα expression only in female fetuses, although this treatment increased iNOS expression in both male and female fetuses in the diabetic group. Diets supplemented with olive oil and not with safflower oil led to a reduction in NO production in male and female fetal lungs. In conclusion, there are gender-dependent changes in PPARα expression and signaling in the fetal lung from diabetic rats, although PPARα activation prevents maternal diabetes-induced lung NO overproduction in both male and female fetuses.     

Multicenter-evaluation of optimal cell density to determine antimicrobial susceptibility for Haemophilus influenzae by the automated RAISUS system when the early-harvested bacterial cells were used

The fully automated microbial system, RAISUS (Nissui Pharmaceutical, Tokyo, Japan) can provide antimicrobial susceptibility test results for the isolates of Haemophilus influenzae. It is known that viable cell concentrations (colony forming unit/ml) of H. influenzae significantly vary depending on the incubation period. For the rapid reporting of antimicrobial susceptibility test results, we evaluated optimal cell density when we prepared the cell suspension using the early-harvested (6 hour incubation) cells for RAISUS. A total of 180 clinical isolates, comprising of 33 ampicillin-susceptible isolates, 114 beta-lactamase negative but ampicillin-resistant isolates and 33 beta-lactamase positive and amoxicillin/clavulanic acid susceptible or -resistant isolates, were included. All the isolates were genetically defined according to the detection of TEM gene and specific mutation (s) in fts I gene. The isolates were incubated on chocolate agar plates for 6 hours, and then the cell suspensions were prepared and adjusted to 0.5, 0.25 and 0.125 McFarland standards through serially dilutions. The respective cell suspensions were tested by the RAISUS AST panels. The % agreements between RAISUS and Clinical and Laboratory Standards Institute standard microdilutions in ampicillin category interpretations were 66.7%(McFarland 0.5), 77.8% (McFarland 0.25) and 83.9%(McFarland 0.125). When the McFarland 0.125 cell suspensions were inoculated, the majority of discrep ant interpretations were minor errors (15.0%) and the occurrence of major error was 3.4%. There was no very major error throughout the study. Essential agreement in MIC determinations (with or within +/- 1 doubling dilution) for 11 beta-lactam antimicrobial agents tested improved to 95.2% by McFarland 0.125 when compared to 77.4% by McFarland 0.5. It was also demonstrated that the viable cell concentrations prepared from 6 hour incubation cultures were 2.5 to 6.5 times higher than those from 22 hour-incubations. With these results, it can be concluded that the early harvested cell suspension of H. influenzae is applicable to RAISUS antimicrobial susceptibility test with lower cell density (McFarland 0.125). With this adjustment, the antimicrobial susceptibility test for H. influenzae will be completed by RAISUS within 26 hours after primary isolation.     

Insecticide resistance in potential vector mosquitoes for West Nile virus in Japan

Culex pipiens complex is the significant vector mosquito of West Nile virus. To take stock of the current situation of insecticide susceptibilities and design an ideal mosquito control strategy, we collected Culex pipiens pallens Coquillet, Culex pipiens form molestus Forskal, and Culex quinquefasciatus Say from fields in Japan and conducted bioassays for five larvicides (fenitrothion, temephos, etofenprox, diflubenzuron, and pyriproxyfen) by using a larval dipping method. Among five insecticides tested, obvious reduced susceptibilities were observed for etofenprox, which is the only pyrethroid compound registered as a larvicide in Japan. Twenty-two of 56 colonies exhibited a >10% survival rate at the etofenprox concentration of 5.7 microg/ml, which is a 10 times higher concentration of the working solution. The LC50 of a colony collected from Fukuoka prefecture for etofenprox exceeded 60 microg/ml (resistance ratio >2,307), and this colony also exhibited cross-resistance to other pyrethroids, permethrin (299-fold) and phenothrin (1,200-fold). The insect growth regulators diflubenzuron and pyriproxyfen were found to be sufficiently effective enough to control Culex larvae present, but decreased sensitivities to these insecticides were slightly detected in some colonies of Cx. p. form molestus collected from urban areas. Several etofenprox-resistant colonies of Cx. p. form molestus exhibited simultaneously decreased susceptibilities to other insecticides, including temephos, diflubenzuron, and pyriproxyfen.     

Nicotine improves probabilistic reward learning in wildtype but not alpha7 nAChR null mutants,yet alpha7 nAChR agonists do not improve probabilistic learning

Cognitive impairments, e.g., reward learning, are present in various psychiatric disorders and warrant treatment. Improving reward-related learning could synergistically enhance psychosocial treatments and cognition generally. A critical first step is to understand the mechanisms underlying reward learning. The dopamine system has been implicated in such learning, but less known is how indirect activation of this system may affect reward learning. We determined the role of alpha7 nicotinic acetylcholine receptors (nAChR) on a probabilistic reversal learning task (PRLT) in mice that includes reward and punishment. Male alpha7 knockout (KO), heterozygous (HT), and wildtype (WT) littermate mice (n?=?84) were treated with vehicle, 0.03, or 0.3?mg/kg nicotine. Two cohorts of C57BL/6NJ male mice were treated with various alpha7 nAChR ligands, including the full agonists PNU282877 and AR-R-17779, the positive allosteric modulator CCMI, the partial agonist SSR180711, and the antagonist methyllycaconitine. All mice were then tested in the PRLT. Nicotine (0.3?mg/kg) significantly improved initial reward learning in alpha7 WT and HT mice but did not improve learning in KO mice, suggesting an involvement of the alpha7 nAChR in the pro-learning effects of nicotine. Neither alpha7 nAChR treatments (PNU282987, AR-R-17779, CCMI, SSR180711, nor methyllycaconitine) affected mouse PRLT performance however. Nicotine improved reward learning via a mechanism that may include alpha7 nAChRs. This improvement unlikely relied solely on alpha7 nAChRs however, since no alpha7 nAChR ligand improved reward learning in normal mice. Future assessments of the effects of other nAChR subtypes on reward learning are needed.