Radiofrequency catheter ablation of idiopathic left ventricular tachycardia in a child

Ventricular tachycardia occurring in apparently normal heart is rare in children. A 9-year-old boy presented with recurrent palpitations and syncope was found to have idiopathic ventricular tachycardia with a right bundle branch block morphology and left axis deviation. Pace mapping and activation mapping were used to localize the site of ventricular tachycardia origin. Radiofrequency catheter ablation successfully abolished this arrhythmia at a site of the midportion of the inferoseptal region of the left ventricle. This boy was free of tachycardia over follow-up of 2 years.

Characteristics of Chinese patients with symptomatic Brugada syndrome in Taiwan

Since 1992, the Brugada syndrome has been increasingly recognized worldwide, although its incidence and distribution remain unclear. In Asia, several cases have been reported in Japan, Thailand, Singapore, and Vietnam. However, little information is available from the Chinese population. Since June 1997, we have identified 10 patients with the diagnosis of the Brugada syndrome from six hospitals in Taiwan. All patients were male with the mean age of 46 +/- 7 years (range 36-61). They all had a normal chemistry profile, coronary angiography and echocardiography. Clinical presentations varied from seizure and syncope to sudden cardiac death. MRI and ultrafast CT of the heart did not show any abnormalities. Sustained ventricular tachycardia/ventricular fibrillation (VF) was induced in 7 of 8 patients who underwent an electrophysiologic study. The pharmacological provocation test was positive in 4 of 5 patients. One of the 4 patients who had a genetic study showed SCN5A gene mutation. An implantable cardioverter defibrillator (ICD) was implanted in 8 patients. During a mean follow-up of 29 +/- 17 months (range 2-54), 3 of 8 patients who had an ICD received appropriate ICD discharges after implantation. These 3 patients who were subsequently treated with antiarrhythmic agents have had no further recurrent ICD discharges. Two patients who refused ICD implantation are alive and well without taking antiarrhythmic agents. Our study showed that the clinical characteristics of our patients are similar to those described in the literature and that ICD is an effective treatment modality for patients with recurrent VF. However, antiarrhythmic agents may be beneficial for suppressing arrhythmia recurrences in selected patients.

FT-IR microspectroscopic study of shot formation in melt-blown webs

We used Fourier transform infrared (FT-IR) microspectroscopy to investigate the chemical nature of fibers and defects called "shot" in melt-blown webs. Spectral differences were observed and evaluated in light of known thermal and oxidative degradation reactions for conditions comparable to those we used for melt blowing. Three different isotactic polypropylene polymers were evaluated in terms of the amount of shot produced and the amount of oxidative degradation exhibited by fibers and shot particles from each polymer. Little oxidative degradation was observed in fibers and the amount of degradation in fibers varied little for the three polymers we evaluated. Substantially more degradation was observed in shot particles, and the amount of degradation varied among the three polymers. Compared to polymer bound for fibers, we concluded that high temperature and mechanical shear in the extruder may introduce more chain scission in polymer bound for shot particles. Autoxidation reactions may occur after melt exits the die, and our data indicated that more oxidative degradation occurred in polymer that became shot particles than polymer that became fibers. The most favorable site for oxidation seemed to be tertiary rather than methylene hydrogen. Overall, the thermal history of polymer that becomes shot particles may be significantly different than the thermal history of polymer that becomes fibers, and this difference may have influenced shot formation.

Multicenter surveillance of antimicrobial resistance of major bacterial pathogens in intensive care units in 2000 in Taiwan

A susceptibility surveillance study of 1,274 bacterial isolates recovered from various clinical specimens from patients in intensive care units (ICUs) of five major teaching hospitals was carried out from March, 2000, to June, 2000, in Taiwan. This study demonstrated a high rate (66%) of oxacillin resistance in Staphylococcus aureus (ORSA), a high rate of nonsusceptibility to penicillin (intermediate, 50% and highly resistant, 8%), and high rates of cefotaxime nonsusceptibility for S. pneumoniae (intermediate, 29% and resistant, 4%), Enterobacter cloacae (57%), Serratia marcescens (34%), and Citrobacter freundii (60%). High rate of ceftazidime nonsusceptibility for Pseudomonas aeruginosa (22%), and high rates of imipenem nonsusceptibility for P. aeruginosa (15%) and Acinetobacter baumannii (22%) were also found. The percentage (11.9%) of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli was greater than that (11.3%) for Klebsiella pneumoniae. Rates of quinupristin-dalfopristin nonsusceptibility for S. pneumoniae (42%), Enterococcus faecium (71%), and ORSA (39%) were high, but no vancomycin-resistant enterococci were found in this study. The resistance rates of some pathogen varied by institution or type of ICUs. Surveillance for antimicrobial resistance among bacterial pathogens in hospitals, particularly in ICU settings with a preexisting higher resistance burden, is mandatory in establishing and/or modifying guidelines for empirical treatment of severe infections in ICU patients caused by these antimicrobial-resistant pathogens.

Candidaemia in patients with dialysis-dependent acute renal failure: aetiology, predisposing and prognostic factors

BACKGROUND

Infections remain the major cause of death among patients with acute renal failure (ARF), especially in severe ARF necessitating dialysis therapy (ARF(d)). Although the clinical features and outcomes of candidaemia in various patient populations have been described, data concerning candidaemic episodes among patients with ARF(d) are scarce. This study investigated the aetiology, predisposing, and prognostic factors for candidaemia in the ARF(d) patient population. Three patient groups were investigated in this study.

METHODS

During an 8-year study period from January 1992 to December 1999, 37 candidaemic episodes that developed among 653 ARF(d) patients were assigned to ARF(d) candidaemic group, and 170 candidaemic episodes developing in patients without ARF(d) or chronic uraemia as the non-ARF(d) candidaemic group, and 28 matched ARF(d) patients without candidaemia were assigned to the ARF(d) control group. Among these groups, clinical characteristics in ARF(d) candidaemia patients, predisposing factors, and outcomes were compared. Four management strategies including central catheter removal, anti-fungal therapy, both, or neither were applied. The prognostic factors for attributable death were evaluated by univariate analysis followed by the multivariate logistic regression analysis.

RESULTS

The proportion of ARF(d) patients with candidaemia was significantly higher than in patients who had no ARF(d) or chronic uraemia (5.7% vs 0.15%, P<0.001). Compared with the non-ARF(d) candidaemic group, systemic lupus erythematosus (SLE), administration of corticosteroid, and central venous catheter-associated candidaemia were more common in the ARF(d) candidaemic group (P<0.05). In matched case-control study, multiple antibiotic usage was shown to be a predisposing factor for developing candidaemia in patients with ARF(d), and corticosteroid therapy has a marginal significance (P=0.059). The occurrence of candidaemia increased the mortality rate of ARF(d) (71% vs 39.2% in ARF(d) control group, P<0.05). By multivariate logistic analysis, the variables associated with attributable death in ARF(d) candidaemic group were identified to be an APACHE II score of >or=18, and anti-fungal therapy for >48 h. Central venous catheters were removed in 32 (86.5%) of the 37 ARF(d) candidaemic patients, among whom the 18 patients who had received anti-fungal therapy for >48 h had a lower attributable death rate than those patients who had not (27.8% vs 64.3%, P<0.05). Of the remaining five patients who did not have their catheter removed, three patients subsequently died and two patients improved only after catheter removal.

CONCLUSIONS

The higher prevalence of candidaemia in ARF(d) patients is due to their underlying illnesses and multiplicity of predisposing factors, rather than ARF and dialysis therapy per se. Predisposing factors include SLE, indwelling central venous catheter, multiple antibiotic usage, and corticosteroid therapy. Prompt anti-fungal therapy and catheter removal should be mandatory for ARF(d) patients with candidaemia.

Outbreak of infection with multidrug-resistant Klebsiella pneumoniae carrying bla(IMP-8) in a university medical center in Taiwan

Klebsiella pneumoniae strains with the transferable carbapenem-hydrolyzing metallo-beta-lactamases, which include IMP- and VIM-type enzymes, remain extremely rare. To investigate whether IMP- or VIM-producing K. pneumoniae isolates had spread at a university medical center in Taiwan, a total of 3,458 clinical isolates of K. pneumoniae consecutively collected in 1999 and 2000 were tested by the agar diffusion method, colony hybridization, PCR, and nucleotide sequencing. A total of 40 isolates (1.2%), or 17 nonrepetitive isolates, from 16 patients were found to carry bla(IMP-8), a metallo-beta-lactamase gene recently identified from a K. pneumoniae strain in Taiwan. Carriage of bla(VIM) or other bla(IMP) genes was detected in none of the remaining isolates. Of the 17 nonrepetitive bla(IMP-8)-positive isolates, 15 isolates (88.2%) appeared susceptible to imipenem (MICs, <or=4 microg/ml) and meropenem (MICs, <or=1 microg/ml), indicating the difficulty in detecting bla(IMP-8) in K. pneumoniae by routine susceptibility tests; 14 isolates (82.4%) produced SHV-12 as well; and 14 isolates (82.4%) were also resistant to fluoroquinolones. The organisms caused wound infections in eight patients and bloodstream infections in three patients. They were not directly associated with the death of nine patients. Before the recovery of the bla(IMP-8)-positive isolates, all 16 patients had undergone various surgical procedures, and 15 patients had been admitted to the surgical intensive care unit, suggesting a nosocomial outbreak. Two major patterns were observed by pulsed-field gel electrophoresis for 14 of the 17 nonrepetitive isolates, indicating that the clonal spread was mainly responsible for the outbreak.

Decreased predominance of papG class II allele in Escherichia coli strains isolated from adults with acute pyelonephritis and urinary tract abnormalities

PURPOSE

We compared the genotypes of fimbriae or adhesions of Escherichia coli causing acute pyelonephritis in adults with and without urinary tract abnormalities.

MATERIALS AND METHODS

We studied a total of 92 E. coli strains isolated from 54 patients with acute pyelonephritis and a normal urinary tract, and 38 with urinary tract abnormalities. Of those with urinary tract abnormalities 13 with moderate to severe hydronephrosis were also considered a separate group for the purpose of analysis. The genes of 7 known fimbriae or adhesins of E. coli were detected by the polymerase chain reaction, including the papG class I to III alleles (PapG adhesins of P-fimbriae), sfa/foc (S-/F1C-fimbriae), fimH (type 1 fimbriae), and afa (afimbrial adhesin). Virulence genes associated with APN were identified by comparing the prevalence of each of these 7 genes in E. coli strains from 54 patients with acute pyelonephritis with a normal urinary tract to the prevalence in the strains from 37 patients with acute cystitis using univariate and multivariate analysis. Differences in the prevalence of the genes associated with acute pyelonephritis and the incidence of underlying illness were then compared in the 3 acute pyelonephritis groups.

RESULTS

On univariate and multivariate analysis the papG class II allele was the only virulence gene associated with acute pyelonephritis (p <0.0001 and 0.001, respectively). No significant difference was noted in the prevalence of underlying medical disease in the 3 acute pyelonephritis groups. The papG class II allele was significantly less predominant in E. coli strains isolated from acute pyelonephritis cases with versus without urinary tract abnormalities (76% versus 93%, p = 0.03). The incidence of the papG class II allele in patients with urinary tract abnormalities and moderate to severe hydronephrosis was less than in those without urinary tract abnormalities (69% versus 93%, p = 0.04).

CONCLUSIONS

Our results imply that the papG class II allele has an important role in E. coli infection in patients with acute pyelonephritis and a normal urinary tract, while urinary tract abnormalities and/or obstruction may permit ascending infection of E. coli strains with lower adhesive ability.

Klebsiella pneumoniae psoas abscess: predominance in diabetic patients and grave prognosis in gas-forming cases

Seven cases of psoas abscess caused by Klebsiella pneumoniae were observed at the National Cheng Kung University Hospital within a period of 4.5 years. These cases constituted 25% of a total 28 episodes of non-tuberculous psoas abscess, ranking second to those caused by Staphylococcus aureus (8 cases). Eight cases of psoas abscess caused by K. pneumoniae were identified from Medline, and 5 of which were reported from Taiwan. Of these 8 cases, 1 neonatal case was excluded, and the remaining 7 adult cases were combined with the 7 cases in this series for analysis. The mean age was 53.8 years, and diabetes mellitus was the most common underlying disease. Fever and pain on the flank and back area were the common findings. The interval between the onset of symptoms and diagnosis ranged from 1 to 60 days. The most common sites of concurrent infection were the urinary tract (6 cases; 43%) and bone (3 cases; 21%). All patients received percutaneous or surgical drainage in addition to antibiotic treatment. Gas formation was present in 5 of the 12 patients recorded, and 4 of them died during hospitalization. Only 1 patient had a metastatic infection with osteomyelitis of the left radius and right humerus; he had experienced 5 episodes of recurrent K. pneumoniae infections in different sites. We concluded that K. pneumoniae should be considered as an important endemic pathogen of psoas abscess in diabetics in Taiwan. The high mortality rate in the gas-forming cases should also be highlighted. Early recognition, empiric antimicrobial coverage for K. pneumoniae, and aggressive drainage or debridement are indicated in these patients.

Outcome of cephalosporin treatment for serious infections due to apparently susceptible organisms producing extended-spectrum beta-lactamases: implications for the clinical microbiology laboratory

Although extended-spectrum beta-lactamases (ESBLs) hydrolyze cephalosporin antibiotics, some ESBL-producing organisms are not resistant to all cephalosporins when tested in vitro. Some authors have suggested that screening klebsiellae or Escherichia coli for ESBL production is not clinically necessary, and when most recently surveyed the majority of American clinical microbiology laboratories did not make efforts to detect ESBLs. We performed a prospective, multinational study of Klebsiella pneumoniae bacteremia and identified 10 patients who were treated for ESBL-producing K. pneumoniae bacteremia with cephalosporins and whose infecting organisms were not resistant in vitro to the utilized cephalosporin. In addition, we reviewed 26 similar cases of severe infections which had previously been reported. Of these 36 patients, 4 had to be excluded from analysis. Of the remaining 32 patients, 100% (4 of 4) patients experienced clinical failure when MICs of the cephalosporin used for treatment were in the intermediate range and 54% (15 of 28) experienced failure when MICs of the cephalosporin used for treatment were in the susceptible range. Thus, it is clinically important to detect ESBL production by klebsiellae or E. coli even when cephalosporin MICs are in the susceptible range (<or = 8 microg/ml) and to report ESBL-producing organisms as resistant to aztreonam and all cephalosporins (with the exception of cephamycins).

Identification of a plasmid encoding SHV-12, TEM-1, and a variant of IMP-2 metallo-beta-lactamase, IMP-8, from a clinical isolate of Klebsiella pneumoniae

A multidrug-resistant plasmid encoding TEM-1, SHV-12, and a variant of IMP-2 metallo-beta-lactamase, designated IMP-8, was identified from a clinical isolate of Klebsiella pneumoniae. There are four nucleotide differences between bla(IMP-2) and bla(IMP-8), resulting in two amino acid differences. bla(IMP-8) was also found to be carried by an integron-borne gene cassette similar to the bla(IMP-2) cassette.

Metallo-beta-lactamases in clinical Pseudomonas isolates in Taiwan and identification of VIM-3, a novel variant of the VIM-2 enzyme

A total of 209 clinical isolates of Pseudomonas (193 Pseudomonas aeruginosa, 10 P. putida, 4 P. stutzeri, and 2 P. fluorescens isolates) with reduced susceptibilities to imipenem and/or ceftazidime were subjected to PCR assays with primers specific for bla(IMP-1), bla(IMP-2), bla(VIM-1), and bla(VIM-2) and sequence analysis to identify the metallo-beta-lactamases (MBLs) prevalent among these organisms in Taiwan; and 21 isolates gave positive results. Five isolates including two P. putida and three P. stutzeri isolates were found to carry bla(IMP-1), and six isolates including five P. putida and one P. stutzeri isolates harbored bla(VIM-2). The remaining 10 isolates were P. aeruginosa, and all were found to carry a novel variant of bla(VIM-2), designated bla(VIM-3). There are only two nucleotide differences between bla(VIM-2) and bla(VIM-3), leading to two amino acid alterations. Our findings indicate that VIM-2 and its variant have become the most prevalent metalloenzymes in Pseudomonas in Taiwan. Southern hybridization with the bla(VIM-2)-, bla(VIM-3)-, and bla(IMP-1 )-specific probes revealed that only two VIM-2-producing P. putida isolates appeared to carry the MBL gene on plasmids. Pulsed-field gel electrophoresis showed that six VIM-3-producing P. aeruginosa isolates and two IMP-1-producing P. stutzeri isolates were genetically related, suggesting that the spread of these MBL genes in Taiwan could be due to clonal dissemination as well as genetic exchange between different clones.

New method for predicting efficiency of heating by measuring bioimpedance during radiofrequency catheter ablation in humans

INTRODUCTION

Efficiency of heating (defined as the average temperature divided by the average power) during radiofrequency (RF) catheter ablation (RFCA) can be predicted by the electrode-tissue contact pressure before RFCA. To predict the efficiency of heating during RFCA, we prospectively measured bioimpedance and correlated the bioimpedance with the efficiency of heating in patients undergoing RFCA for supraventricular tachycardias.

METHOD AND RESULTS

Of 239 RF applications in 55 patients, bioimpedance was measured from the distal pair of the electrodes of the ablation catheter using an extremely low current (10 microA at 45 kHz). Tip electrode temperature was measured with a closed-loop RF generator. Efficiency of heating and the difference (delta bioimpedance) between preablation bioimpedance (measured from the target ablation site) and baseline bioimpedance (measured in the right atrium without tissue contact) were calculated. There was significant positive correlation between preablation bioimpedance and efficiency of heating (regression coefficient = 0.053; P = 0.003) and between delta bioimpedance and efficiency of heating (regression coefficient = 0.067; P = 0.003). The highest degree of correlation was found during RFCA of the accessory pathways in the left free wall (regression coefficient = 0.14; P < 0.01). With preablation delta bioimpedance >21.5 ohms, applications targeted at the left free-wall, left posteroseptal, or right septal accessory pathways had a greater likelihood of achieving effective tissue heating (defined as maximal temperature achieved >55 degrees C).

CONCLUSION

Both preablation bioimpedance and delta bioimpedance have positive correlation with efficiency of heating during RFCA of supraventricular tachycardia. Measuring preablation bioimpedance appears to be a useful tool for predicting the efficiency of heating during RFCA.

Clostridium bacteremia: emphasis on the poor prognosis in cirrhotic patients

Bacteremic episodes caused by anaerobes are unusual and the clinical importance of Clostridium bacteremia remains unclear. This retrospective case study examined the risk factors among a group of patients who developed Clostridium bacteremia. Medical records from 73 episodes of clostridial bacteremia in 73 patients treated in a medical center during an 11-year period were reviewed. Of all episodes, 96% were community-acquired. Twelve percent of patients had polymicrobial bacteremia, with Escherichia coli being the most common accompanying bacterium. Diabetes mellitus (26%) and liver cirrhosis (25%) were the most common underlying diseases. The most common etiological organisms were Clostridium perfringens (77%), Clostridium bifermentans (9%), and Clostridium septicum (4%). Only one patient with C. septicum bacteremia had a histocytotoxic infection, which was a fatal gas gangrene. Univariate analysis of data from patients with monomicrobial Clostridium bacteremia revealed that younger age (age < 65 years), underlying liver cirrhosis, and presence of septic shock at initial presentation were associated with fatality; but only the latter two variables were independently associated with fatality in multivariate logistic regression analysis. Appropriate antimicrobial therapy for monomicrobial Clostridium bacteremia did not significantly affect clinical outcomes, which might suggest that Clostridium species in the bloodstream can be regarded as merely contaminants or transient bacteremia. This suggestion was not supported by the finding that seven of 13 cirrhotic patients with monomicrobial Clostridium bacteremia died of sepsis, of whom six had not receive appropriate antimicrobial therapy. Therefore, the clinical importance of Clostridium bacteremia should be interpreted with caution because of its high risk of mortality in susceptible hosts, particularly cirrhotic patients, who do not receive appropriate therapy timely.

Serotyping and antimicrobial susceptibility of group B Streptococcus over an eight-year period in southern Taiwan

The increase in penicillin resistance among pneumococci and viridans streptococci and the development of serotype-specific conjugate vaccine have increased the need for knowledge of the antimicrobial susceptibility and the capsular serotypes of group B streptococci. Over an 8-year period, 351 group B streptococcal isolates from southern Taiwan were tested for antimicrobial susceptibility and serotype determination. Eighty-seven percent of the isolates were typeable. Types III (28.5%) and V (27.1%) were the most common serotypes. The occurrence of type V isolates increased with age, while that of type III isolates decreased with age, showing a predominance in children less than 1 year of age. Of 118 isolates from cases of invasive infection, types Ia, Ib, II, III, IV, and V accounted for 12.7, 11.9, 0.8, 33, 1.7, and 26.3%, respectively. Using the agar dilution method, all isolates were found to be susceptible to penicillin, cefotaxime, and vancomycin, 99.4% to ofloxacin, 78.1% to chloramphenicol, 63.2% to azithromycin, 62.6% to erythromycin, 57.3% to clindamycin, and 2.8% to tetracycline. Chloramphenicol resistance was associated with type III isolates (59 of 100, 59%) and erythromycin and azithromycin resistance with type Ib isolates (25 of 33 176%], and 21 of 33 [64%], respectively). Thus, 72% of the isolates from invasive infections were serotype III, V, or Ia, and penicillin remains the drug of choice for treatment or prophylaxis of group B streptococcal infections in southern Taiwan, despite the high prevalence of penicillin resistance among Streptococcus pneumoniae and viridans streptococci.

In vitro and in vivo combinations of cefotaxime and minocycline against Aeromonas hydrophila

The activities of cefotaxime and minocycline against Aeromonas hydrophila were investigated. Cefotaxime (4 times the MIC) plus minocycline (0.75 times the MIC) elicited an inhibitory effect for 48 h in a time-kill study, and more infected mice treated with both drugs survived (91%) than survived after treatment with cefotaxime (9%) or minocycline (44%) alone, suggesting that cefotaxime and minocycline act synergistically against A. hydrophila.

Mechanisms of relaxant action of S-petasin and S-isopetasin, sesquiterpenes of Petasites formosanus, in isolated guinea pig trachea

We investigated the mechanisms of action of S-petasin and S-isopetasin, from Petasites formosanus Kitamura which is used as a folk medicine for treating hypertension, tumors, and asthma in Taiwan. The tension changes of tracheal segments were isometrically recorded on a polygraph. S-Petasin and S-isopetasin non-competitively inhibited cumulative histamine-, and carbachol-induced contractions with an exception that S-isopetasin produced a parallel, rightward shift of the concentration-response curve of carbachol in a competitive manner. S-Petasin also non-competitively inhibited cumulative Ca(2+)-induced contractions in depolarized (K+, 60 mM; histamine, 100 microM; or carbachol, 10 microM) guinea-pig tracheas. S-Isopetasin did in depolarized (K+, 60 mM) trachea too. The nifedipine (10 microM)-remaining tension of carbachol (0.2 microM)-induced precontraction was further relaxed by S-petasin or S-isopetasin, suggesting that no matter whether either blocked VDCCs or not, S-petasin or S-isopetasin may have other mechanisms of relaxant action. The relaxant effect of S-petasin or S-isopetasin was unaffected by the presence of propranolol (1 microM), 2',5'-dideoxyadenosine (10 microM), methylene blue (25 microM), glibenclamide (10 microM), N omega-nitro-L-arginine (20 microM), or alpha-chymotrypsin (1 U/ml). However, S-petasin (100-300 microM), but not S-isopetasin, significantly inhibited cAMP-, but not cGMP-dependent PDE activity of the trachealis. The above results reveal that the mechanisms of relaxant action of S-petasin and S-isopetasin may be primarily due to its non-specific antispasmodic and antimuscarinic effects, respectively.

Changes in K value and microorganisms of tilapia fillet during storage at high-pressure, normal temperature

This study determined the effect of high-pressure, normal temperature (25 degrees C) storage on tilapia fillets. After pressurization, the fillets were stored at normal condition (1 atm [1 atm = 101.29 kPa] and 25 degrees C) for 12 h to evaluate the changes of microbes and K value. The fillets stored at 2,000 atm for 12 h still kept the K value, a freshness index that represents putrefaction with the value beyond 60%, still below 40%, and the K value of the meat without pressurization was up to 92%. Total plate counts of the fillets stored at below 1,000 atm for 12 h were maintained at the value of 4.7 log CFU/g of meat, which was similar to the initial level. However, the counts were obviously decreased to about 2.0 log CFU/g of meat for the fillets stored at above 2,000 atm. The same effect was obtained for psychrophilic bacteria. Enzymes and microbes reactivated apparently after 12 h of normal condition storage of mild pressurized fillets. The study demonstrates that high-pressure storage can inhibit the putrefaction of tilapia meat but no longer after that.

Dissemination of CTX-M-3 and CMY-2 beta-lactamases among clinical isolates of Escherichia coli in southern Taiwan

A total of 1,210 clinical isolates of Escherichia coli collected from a university hospital in southern Taiwan were screened for production of extended-spectrum beta-lactamases (ESBLs). Expression of classical ESBLs (resistant to extended-spectrum beta-lactam agents and susceptible to beta-lactam inhibitors) was inferred in 18 isolates by the phenotypic confirmatory test. These included 10 isolates producing CTX-M-3, 2 strains carrying SHV-12, 1 strain harboring SHV-5, 1 strain expressing TEM-10, and 4 strains producing unidentifiable ESBLs with a pI of 8.05, 8.0, or 7.4. Eighteen isolates that showed decreased susceptibilities to ceftazidime and/or cefotaxime, negative results for the confirmatory test, and high-level resistance to cefoxitin (MICs of >/=128 microg/ml) were also investigated. Five isolates were found to produce CMY-2 AmpC enzymes, one isolate carried both CTX-M-3 and CMY-2, and the remaining three and nine isolates expressed putative AmpC beta-lactamases with pIs of >9.0 and 8.9, respectively. Thus, together with the isolate producing CTX-M-3 and CMY-2, 19 (1.6%) isolates produced classical ESBLs. Pulsed-field gel electrophoresis revealed that all isolates carrying CTX-M-3 and/or CMY-2 were genetically unrelated, indicating that dissemination of resistance plasmids was responsible for the spread of these two enzymes among E. coli in this area. Among the 16 isolates expressing CTX-M-3 and/or CMY-2, 5 might have colonized outside the hospital environment. Our data indicate that CTX-M-3 and CMY-2, two beta-lactamases initially identified in Europe, have been disseminated to and are prevalent in Taiwan.

Relaxant effects of petasins in isolated guinea pig trachea and their structure-activity relationships

In the present study, we attempted to compare four petasins, isolated from Petasites formosanus Kitamura, and to look for structure-activity relationships, which may be helpful for synthesizing more active compounds for the treatment of asthma. Four petasins, including petasin, isopetasin, S-petasin and S-isopetasin, concentration-dependently relaxed histamine (10 microM)-, carbachol (0.2 microM)-, KCl (30 mM)-, and leukotriene D4 (10 nM)-induced precontractions of isolated guinea pig trachealis. The IC50 values strongly showed that the relaxant effects of the sulfur-containing petasins, S-petasin and S-isopetasin, were more potent than those of non-sulfur-containing petasins, petasin and isopetasin. S-isopetasin, with IC50 values around 10 microM, selectively relaxed carbachol- and KCl-induced precontractions, and had almost no effects (IC50s > 300 microM) on histamine- and leukotriene D4-induced precontractions. However, S-petasin, with IC50 values about 6-9 microM, non-selectively relaxed the precontractions induced by all these contractile agents. The influence of isomerization of either petasin to isopetasin or S-petasin to S-isopetasin on the relaxant effects is not clear.

Tetanus of the elderly

The medical records of 20 tetanus patients who were treated at a university teaching hospital in Taiwan during the period from October 1991 to July 1999 were retrospectively analyzed. There were 18 adults (six males and 12 females) with unknown previous immunization status and ages ranging from 34 to 87 years old (mean 63 years). Two patients were children, aged 3 and 5 years old, respectively; both of them had incomplete tetanus immunization. Of the 17 patients reporting previous acute injury, 10 had tetanus-prone wounds. Four of six patients who sought medical help for wound management received tetanus toxoid, but none received tetanus immunoglobulins. The most common symptoms were trismus, dysphagia, and muscular rigidity. Specific treatment consisted of active and passive immunization, wound management, parenteral antibiotics, and benzodiazepines, muscle relaxants or neuromuscular blockades for control of spasms and sedation. All adults were admitted to the intensive care unit and an artificial airway was established. Fourteen of them required ventilator support during the illness. Prophylactic tracheostomy was performed within 24 h after arrival in 12 (92%) of 13 patients. Two patients died with an overall mortality rate of 10%. Sequelae were rare in the patients who survived. Because of inclusion of the diphtheria-pertussis-tetanus (DPT) vaccine in the national Children's Vaccine Program and improvement in obstetrical practices and neonatal care in Taiwan, tetanus mainly occurs in people older than 65 years instead of neonates or children. Waning immunity to tetanus in the elderly and poor wound management practices by primary care physicians were contributory factors.

Mechanisms involved in the antiplatelet activity of Staphylococcus aureus lipoteichoic acid in human platelets

In this study, gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose-dependently (0.1-1.0 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LTA also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. LTA (0.5 and 1.0 microg/ml) also significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LTA (0.1-1.0 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. Rapid phosphorylation of a platelet protein of Mr. 47,000 (P47), a marker of protein kinase C activation, was triggered by PDBu (30 nM). This phosphorylation was markedly inhibited by LTA (0.5 and 1.0 microg/ml) within a 10-min incubation period. These results indicate that the antiplatelet activity of LTA may be involved in the following pathways: LTA's effects may initially be due to induction of conformational changes in the platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in gram-positive septicemic and endotoxemic patients.

Comparison of the MB/BacT and BACTEC MGIT 960 system for recovery of mycobacteria from clinical specimens

A total of 543 specimens were cultured in parallel with the MB/BacT and BACTEC MGIT 960 systems and on the conventional solid media. Mycobacteria were identified from 95 (17.5%) specimens, including 63 (66.3%) Mycobacterium tuberculosis and 32 (33.7%) nontuberculous mycobacteria. The recovery rates for the MB/BacT, MGIT 960, and solid media were 91.6, 87.4, and 54.7%, respectively, for all mycobacteria; the recovery rates were 93.6, 88.9, and 63.4%, respectively, for M. tuberculosis complex alone, and 87.5, 84.4, and 37.5%, respectively, for all nontuberculous mycobacteria. The mean times to detection of all mycobacteria by individual systems were 13. 9, 8.7, 31.7 days for the MB/BacT, MGIT 960 and solid media, respectively, 13.9, 9.3, 32.9 days for M. tuberculosis alone, and 14. 1, 8.1, 27.2 days for all nontuberculous mycobacteria. The contamination rates of the MB/BacT and MGIT 960 were 10.2 and 5.4%, respectively. With regard to detection times and recovery rates, both automated systems are superior to the conventional media (all p < 0.005). As compared to the MB/BacT, the MGIT 960 detected mycobacterial growth more rapidly (p < 0.001), and had a lower contamination rate (p = 0.003); however, there was no statistically significant difference in recovery rates between these two systems. These results indicate that both MGIT 960 and MB/BacT systems are rapid, sensitive, and efficient methods for the recovery of mycobacteria from clinical specimens.

Clinical features and therapeutic implications of 104 episodes of monomicrobial Aeromonas bacteraemia

OBJECTIVES

Aeromonas bacteraemia is not a common infectious disease, but can cause a grave outcome in infected cases. In this study, clinical presentations and prognostic factors of cases of monomicrobial Aeromonas bacteraemia were analysed. Also, the impact of beta-lactam and aminoglycoside in combination and of emerging cephalosporin-resistance during therapy was discussed.

METHODS

From 1989 to 1998 in a medical centre in southern Taiwan, those cases with monomicrobial Aeromonas bacteraemia were included for study.

RESULTS

A total of 104 episodes of monomicrobial Aeromonas bacteraemia, accounting for 74% of all Aeromonas bacteraemia, were encountered. The infections usually occurred in the patients with hepatic cirrhosis (54%) or malignancy (21%) and were community-acquired (74%). Cases of community-acquired bacteraemia were more likely to have cirrhosis, a high severity score at onset, and a worse prognosis than those of nosocomial bacteraemia did and nosocomial isolates were less susceptible to cefoxitin and cefotaxime. Forty-three percent of cases had a concomitant infection focus, such as primary peritonitis, invasive cellulitis or necrotizing fasciitis, biliary tract or burn wound infections. Crude fatality rate within 2 weeks after the onset was 30%. Secondary bacteraemia and a higher severity score ( > or = 4) for illness at the first presentation were independently associated with a fatal outcome. The therapeutic superiority of beta-lactam and aminoglycoside in combination cannot be demonstrated in patients with Aeromonas bacteraemia. Cefotaxime resistance emerged in 3.4% of 58 patients treated with a cephalosporin for at least 72 h. None of the community-acquired isolates, but one-quarter of the nosocomial isolates, were resistant to cefotaxime.

CONCLUSIONS

Aeromonas bacteraemia usually occurred in patients with liver cirrhosis or malignancy, and heralded a poor prognosis, especially while associated with a relevant infectious source or with a higher severity score at presentation. The superiority of aminoglycoside and beta-lactam in combination cannot be demonstrated while treating those patients, and the emergence of antimicrobial resistance to cephalosporin was a rare event during cephalosporin therapy. Thus, a broad-spectrum cephalosporin remains one of the antimicrobial alternatives for invasive community-acquired Aeromonas infections.

Epidemiology of ciprofloxacin resistance and its relationship to extended-spectrum beta-lactamase production in Klebsiella pneumoniae isolates causing bacteremia

A prospective study of Klebsiella pneumoniae bacteremia was performed in 12 hospitals in 7 countries. Of 452 episodes of bacteremia, 25 (5.5%) were caused by K. pneumoniae that was resistant in vitro to ciprofloxacin. Extended-spectrum beta-lactamase (ESBL) production was detected in 15 (60%) of 25 ciprofloxacin-resistant isolates, compared with 68 (16%) of 427 ciprofloxacin-susceptible strains (P=.0001). Multivariate analysis revealed that risk factors for ciprofloxacin resistance in K. pneumoniae included prior receipt of a quinolone (P=.0065) and an ESBL-producing strain (P=.012). In all, 18% of ESBL-producing isolates were also ciprofloxacin-resistant. Pulsed-field gel electrophoresis showed that 11 of the 15 ciprofloxacin-resistant ESBL-producing strains belonged to just 4 genotypes, suggesting that patient-to-patient transmission of such strains occurred. The close relationship between ESBL production and ciprofloxacin resistance is particularly worrisome because the first reported instance of plasmid-mediated ciprofloxacin resistance has been in an isolate of K. pneumoniae also possessing an ESBL.

Arcobacter butzleri bacteremia in a patient with liver cirrhosis

Invasive Arcobacter butzleri infection in humans has been rarely described. We report a 60-year-old man with liver cirrhosis who presented with high fever and esophageal variceal bleeding. Two aerobic blood cultures grew Campylobacter-like organisms. The biochemical reactions of the isolate were inconclusive, while sequence analysis of the 16S rRNA gene definitively identified the organism as A. butzleri. The patient's bleeding stopped after endoscopic sclerosing therapy. Although the organism appeared to be resistant to cephalosporins on the basis of the minimum inhibitory concentrations determined with the E test, the fever resolved with parenteral cefuroxime. Whether the clinical improvement was related to cephalosporin therapy or to the self-limited nature of Arcobacter bacteremia is not known.