Wanla Kulwichit

Clinical and Epidemiological Analyses of Human Pythiosis in Thailand

BACKGROUND Pythiosis is an emerging and life-threatening infectious disease in humans and animals that is caused by the pathogenic oomycete Pythium insidiosum. Human pythiosis is found mostly in Thailand, although disease in animals has been increasingly reported worldwide. Clinical information on human pythiosis is limited, and health care professionals are unfamiliar with the disease, leading to underdiagnosis, delayed treatment, and poor prognosis. METHODS To retrospectively study the clinical and epidemiological features of human pythiosis, we analyzed clinical data from patients with pythiosis diagnosed during the period of January 1985 through June 2003 at 9 tertiary care hospitals throughout Thailand. RESULTS A total of 102 cases of human pythiosis were documented nationwide. A substantial proportion (40%) of cases occurred in the last 4 years of the 18-year study interval. Clinical presentations fell into 4 groups: cutaneous/subcutaneous cases (5% of cases), vascular cases (59%), ocular cases (33%), and disseminated cases (3%). Almost all patients with cutaneous/subcutaneous, vascular, and disseminated pythiosis (85%) had underlying thalassemia-hemoglobinopathy syndrome. Most ocular cases (84%) were associated with no underlying disease. A majority of the patients were male (71%), were aged 20-60 years (86%), and reported an agricultural occupation (75%). Regarding treatment outcomes, all patients with disseminated infection died; 78% of patients with vascular disease required limb amputation, and 40% of these patients died; and 79% of patients with ocular pythiosis required enucleation/evisceration. CONCLUSIONS Here, we report, to our knowledge, the largest case study of human pythiosis. The disease has high rates of morbidity and mortality. Early diagnosis and effective treatment are urgently needed to improve clinical outcomes. Because P. insidiosum is distributed worldwide and can infect healthy individuals, an awareness of human pythiosis should be promoted in Thailand and in other countries.

LMP1 signaling and activation of NF-κB in LMP1 transgenic mice

Transgenic mice expressing Epstein–Barr virus (EBV) latent membrane protein 1 (LMP1) under the control of an immunoglobulin heavy-chain promoter and enhancer develop lymphoma at a threefold higher incidence than LMP1-negative mice. In vitro, LMP1 activates numerous signaling pathways including p38, c-Jun N terminal kinase (JNK), phosphatidylinositol 3 kinase (PI3K)/Akt, and NF-κB through interactions with tumor necrosis receptor-associated factors (TRAFs). These pathways are frequently activated in EBV-associated malignancies, although their activation cannot be definitively linked to LMP1 expression in vivo. In this study, interactions between LMP1 and TRAFs and the activation of PI3K/Akt, JNK, p38, and NF-κB were examined in LMP1 transgenic mice. LMP1 co-immunoprecipitated with TRAFs 1, 2, and 3. Akt, JNK, and p38 were activated in LMP1-positive and -negative splenocytes as well as LMP1-positive and -negative lymphomas. Multiple forms of NF-κB were activated in healthy splenocytes from LMP1 transgenic mice, in contrast to healthy splenocytes from LMP1-negative mice. However, in both LMP1-positive and -negative lymphomas, only the oncogenic NF-κB c-Rel, was specifically activated. Similarly to EBV-associated malignancies, p53 protein was detected at high levels in the transgenic lymphomas, although mutations were not detected in the p53 gene. These data indicate that NF-κB is activated in LMP1-positive healthy splenocytes; however, NF-κB c-Rel is specifically activated in both the transgenic lymphomas and in the rare lymphomas that develop in negative mice. The LMP1-mediated activation of NF-κB may contribute to the specific activation of c-Rel and lead to the increased development of lymphoma in the LMP1 transgenic mice.

Accuracies of Leuconostoc phenotypic identification: a comparison of API systems and conventional phenotypic assays

BackgroundCommercial diagnostics are commonly used to identify gram-positive bacteria. Errors have been reported mostly at the species level. We have found certain phenotypic criteria used in API systems which significantly misidentify Leuconostoc, an emerging human pathogen, at the genus level. We also attempt to find practical, conventional phenotypic assays for accurate identification of this group of bacteria.MethodsClinical isolates of catalase-negative, gram-positive coccoid or coccobacillary bacteria with non-β hemolysis in our institute during 1997–2004 were subject to an identification aid by API 20 STREP, following the instruction manual, as an aid to conventional phenotypic tests. Those identified as Leuconostoc by API 20 STREP were re-examined by the same kit and also by API 50 CHL according to the instruction manuals, by our Leuconostoc conventional phenotypic assays, by Leuconostoc- and Lactobacillus-specific PCRs, and, where possible, by 16S rDNA sequence analysis. In addition, catalase-negative gram-positive isolates during 2005–2006 which were resistant to vancomycin at high levels were also evaluated by the same phenotypic and genotypic assays.ResultsOut of several thousands of clinical gram-positive isolates, 26 catalase negative gram-positive isolates initially identified as Leuconostoc by API 20 STREP and 7 vancomycin-resistant gram-positive catalase-negative bacteria entered the study. 11 out of the 26 isolates and all the 7 isolates were identified as Leuconostoc by API 20 STREP. Only 5 isolates, however, were confirmed by both genotypic and all defined conventional phenotypic criteria. API 50 CHL also failed to reliably provide accurate identification of Leuconostoc. We have identified key problem tests in API 20 STREP leading to misidentification of the bacteria. A simple, conventional set of phenotypic tests for Leuconostoc identification is proposed.ConclusionThe current API systems cannot accurately identify Leuconostoc. Identification of vancomycin-resistant, catalase-negative gram-positive bacteria should be performed by a few practical phenotypic assays, with assistance of genotypic assays where available.

Drug-resistant nontyphoidal Salmonella bacteremia, Thailand.

To the Editor: Despite improved public health, serious infections with nontyphoidal Salmonella enterica remain a major clinical and public health concern in Thailand and worldwide (1,2). Life-threatening Salmonella infections resistant to fluoroquinolones, extended-spectrum cephalosporins, or both, have been increasingly reported (3). Use of antimicrobial drugs for disease prevention and growth promotion in food animals has been implicated in this increase in drug resistance (4). Because of extensive global travel, such increases affect the medical community domestically and internationally (5). We report a pilot survey of drug resistance in Salmonella spp. in Thailand.

Mycotic aneurysm caused by Burkholderia pseudomallei with negative blood cultures.

We describe a case of bacterial aortitis caused by Burkholderia pseudomallei. This patient presented with prolonged fever and hoarseness of voice. Aneurysm removal with Dacron graft replacement was performed, followed by a prolonged course of antibiotics. The patient has progressed satisfactorily without recurrence of symptoms. Previous case reports are summarized.

Near-fatal bleeding, senna, and the opposite of lettuce.

In February, 2006, a 45-year-old woman went to her local hospital with diff use abdominal pain. When the hospital realised that she might have a serious illness, she was brought by ambulance to our hospital, for insurance reasons. By the time she arrived, the pain had been present for 15 h. Her aortic valve had been replaced in 1999, but she had had no abdominal problems until mid-2005, when she developed a tendency to constipation. She had therefore taken 1–2 tablets of a senna-based laxative, once or twice a week. She had seen no need to tell her doctors about the laxative. For 3 weeks preceding her admission she had taken several tablets of laxative a day, and passed loose, watery stools up to three times a day. The day before the pain started, she had taken many tablets, after passing no stool for 2 days. She had then passed three watery stools, followed by three bloody stools— some blood was fresh and red, and some old and black. She had no other medical history of note; notably, she had no psychiatric disorder. She was on no drugs other than warfarin, which she had taken ever since her operation. She took her warfarin regularly, and her international normalised ratio (INR) had been in the therapeutic range for years. Her diet, including her consumption of green vegetables, varied little. She took no herbal medications. 25 days before admission, her INR had been 2·3. She was hypotensive and tachycardic. Her abdomen was distended, with widespread tenderness and guarding. Rectal examination revealed fresh blood. Blood tests showed a haemoglobin concentration of only 84 g/L; the platelet count was normal, at 164×109/L, but the INR was 11·9; the activated partial thromboplastin time was 92·4 s (control time 29·3 s). The concentrations of bilirubin and aspartate aminotransferase were slightly high, at 33·5 μmol/L and 48 U/L, respectively, but the results of liver function tests were otherwise normal. CT of the abdomen showed extensive haematoma in the pelvic, paracolic, and subhepatic regions. We admitted the patient for several days, during which we gave her vitamin K, fresh frozen plasma, and packed red cells. She subsequently resumed taking warfarin, and stopped taking laxatives in excess; her INR rapidly returned to the target range, where it has remained ever since. When last seen, in November, 2007, she was well. Vitamin K is an essential cofactor for γ-carboxylation, the post-translational modifi cation of coagulation factors II, VII, IX, and X (fi gure). Although vitamin K is also a cofactor for the γ-carboxylation of protein C and protein S, lack of vitamin K reduces coagulation. Green leafy vegetables have especially high con centrations of vitamin K, but the vitamin K in vegetable oils and soya may be more bioavailable. Many patients on warfarin are aware—as, indeed, was our patient—that their dietary consumption of vitamin K should remain fairly constant. However, not all are aware that diarrhoea can reduce absorption of vitamin K, and increase the risk of bleeding. Although some physicians recommend halving the dose of warfarin when the patient has diarrhoea, many doctors seem unaware of the increased risk of bleeding—and many textbooks, formularies, and patient-information leafl ets fail to mention the increased risk, or do so only in passing. Cases like ours will continue to occur, until doctors and patients are better informed.

Glucose-6-phosphate dehydrogenase deficiency, vitamin K, and ambiguity in medical textbooks.

Accessible online at: www.karger.com/aha Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common inherited enzyme deficiency and affects some 400 million people worldwide. Severe intravascular haemolysis can develop following systemic infections and certain medications. Vitamin K1 is frequently administered in patients with active haemorrhage whenever vitamin K deficiency is considered a possible contributor. Interestingly, with regard to G6PD-deficient patients, different forms of vitamin K are on the lists of drugs to be avoided in some medical textbooks [1–3], while others claim that vitamin K is safe [4, 5]. Here, we present a clinical situation where incorrect conclusions could be drawn from potentially misleading information in some leading medical textbooks. A 20-year-old man presented with 6 days of fever and 2 days of gross haematuria and melaena. Investigations revealed thrombocytopaenia, elevation of liver enzymes, and prolongation of PT and PTT. Because a contribution of vitamin K depletion as a result of a week’s illness could not be excluded [1], 10 mg of intravenous vitamin K1 were given, with partial reversal of coagulopathy. The fol-

High prevalence of ceftriaxone resistance among invasive Salmonella enterica serotype Choleraesuis isolates in Thailand: The emergence and increase of CTX-M-55 in ciprofloxacin-resistant S. Choleraesuis isolates

S. Choleraesuis is a highly invasive zoonotic pathogen that causes a serious systemic infection in humans. The emergence and increase of resistance to ceftriaxone and ciprofloxacin among S. Choleraesuis has become a serious therapeutic problem. The present study demonstrated high frequency of antimicrobial resistance in Salmonella Choleraesuis among 414 nontyphoidal Salmonella isolates from bacteremic patients in Thailand. High rates of ceftriaxone (58.3%) and ciprofloxacin (19.6%) resistances were observed in S. Choleraesuis isolates. The dissemination of the self-transferable blaCTX-M-14-carrying IncFIIs, IncFII, and IncI1 plasmids and blaCMY-2-carrying IncA/C plasmid along with the clonal spread of blaCMY-2-harbouring S. Choleraesuis isolates contributed to the high frequency of resistance to extended-spectrum cephalosporins (ESCs; third- and fourth-generation cephalosporins) during 2005-2007. We reported the first occurrence of ceftazidime-hydrolysing CTX-M-55 in S. Choleraesuis isolates which dramatically increased and became the most abundant CTX-M variant among ESC-resistant S. Choleraesuis isolates during 2012-2016. The spread of clone pulsotype B3 was due to the dissemination of IncA/C plasmids carrying both blaCTX-M-55 and qnrS1 among ciprofloxacin-resistant S. Choleraesuis isolates harbouring D87G in GyrA. These isolates were apparently responsible for the high rates of co-resistance to ESCs and ciprofloxacin (51.3%) during 2012-2016. This study emphasizes the importance to have an action plan to control the dissemination of antimicrobial resistance in S. Choleraesuis since this poses a threat to global health due to travel and trade in animal food products.