Botulin toxin: a weapon in terrorism.

Clostridium botulinum, the causative agent of botulism is an anaerobic, spore forming gram-positive bacillus. C. botulinum causes three types of botulism; foodborne botulism, wound botulism, and infant botulism. Most strains of the bacterium produce a potent, muscle-paralyzing neurotoxin. Respiratory failure secondary to paralysis of the respiratory muscles can lead to death unless appropriate therapy is promptly initiated. Due to the severity and potency of this neurotoxin, its importance as a biological weapon is of major concern to public health officials.     

Antimicrobial susceptibility of clinical isolates of non-jejuni/coli campylobacters and arcobacters from Belgium

OBJECTIVES: To determine the susceptibility of non-jejuni/coli campylobacters and arcobacters isolated from diarrhoeal stool specimens in Belgium. METHODS: The MICs were determined using Etest for six antimicrobial agents including ampicillin, erythromycin, nalidixic acid, ciprofloxacin, gentamicin and tetracycline for the most frequently isolated non-jejuni/coli campylobacter and arcobacter strains in two University Hospital laboratories between 1995 and 2005. RESULTS: In total, 85 Campylobacter upsaliensis, 20 Campylobacter concisus, 11 Campylobacter fetus, 61 Arcobacter butzleri and 10 Arcobacter cryaerophilus isolates were tested. Most C. upsaliensis strains were susceptible to ampicillin (100%), gentamicin (100%), ciprofloxacin (94.1%) and tetracycline (100%), whereas 11.8 and 12.9% were resistant to nalidixic acid and erythromycin, respectively. For A. butzleri, 78.7% of isolates were susceptible to ampicillin and erythromycin. Most A. butzleri isolates were susceptible to ciprofloxacin (96.7%), nalidixic acid (82.0%), gentamicin (100%) and tetracycline (100%). All C. concisus strains were fully susceptible to ampicillin and tetracycline, but 5% of them were resistant to gentamicin, ciprofloxacin and erythromycin. Nearly all C. fetus and A. cryaerophilus strains were susceptible to erythromycin but the results should be interpreted with caution since only a small number of strains were tested. CONCLUSIONS: Fluoroquinolones should be considered in the treatment of severe C. upsaliensis and A. butzleri infection. When clinically indicated, erythromycin remains the first choice for the treatment of intestinal campylobacteriosis caused by C. concisus and C. fetus.     

2008-2009年中国部分地区脑膜炎奈瑟菌对体外抗生素敏感性检测

目的了解2008-2009年中国部分地区脑膜炎奈瑟菌(Nm)分离株的抗生素敏感性变化趋势。方法药敏纸片扩散(K-B)法和E-test试纸条检测方法对本研究室2008-2009年收集的68株分离自患者和健康带菌者菌株进行体外抗菌药物敏感性检测。结果所有菌株对3种治疗药物头孢噻肟、头孢曲松和氯霉素均敏感,1株C群患者菌株对美洛培南耐药,13株对青霉素不敏感菌株,6株对氨苄西林不敏感菌株。6种预防用药组中,除1株Y群带菌者菌株对利福平耐药外,其他菌株对阿奇霉素、米诺环素和利福平均敏感,70.59%菌株对萘啶酸,72.06%对环丙沙星,95.59%对复方新诺明耐药。W135群带菌者菌株对青霉素和氨苄西林敏感株比例较大,2株对磺胺类药物敏感。患者菌株和带菌者菌株药敏谱略有不同。结论磺胺类和喹诺酮类药物仍不被考虑作为流脑的预防性药物,加强对青霉素和氨苄西林治疗药物在各种血清群Nm的耐药性监测。长期对Nm药敏监测非常必要,对流行性脑脊髓膜炎预防和治疗药物的选择应因时因地而宜。     

Synergistic Activity of Gentamicin with Trimethoprim or Sulfamethoxazole-Trimethoprim Against Escherichia coli and Klebsiella pneumoniae

The effect of combinations of gentamicin with trimethoprim or sulfamethoxazole-trimethoprim against clinical isolates of Escherichia coli (11 strains) and Klebsiella pneumoniae (12 strains) was examined by using a microdilution checkerboard technique. All isolates were susceptible to each antimicrobial agent. Synergism, defined as at least a 2-log(2)-dilution lowering of the minimal inhibitory concentration of either antibiotic in the combination compared with the minimal inhibitory concentration of the antibiotic alone, was observed with 15 of 23 (65%) isolates tested against trimethoprim and gentamicin and 14 of 23 (61%) isolates tested against sulfamethoxazole-trimethoprim and gentamicin. A 3-log(2)-dilution lowering of the minimal inhibitory concentration of either antibiotic was observed in 7 of 23 (30%) trimethoprim and gentamicin trials and 3 of 23 (13%) sulfamethoxazole-trimethoprim and gentamicin trials. Antagonism was observed in 3 of 46 combination trials and only with strains of K. pneumoniae.     

Serotype distribution of penicillin-resistant pneumococci and their susceptibilities to seven antimicrobial agents

A total of 229 clinical isolates of Streptococcus pneumoniae recovered from 225 patients were serotyped and tested for susceptibility to penicillin G, ampicillin, mezlocillin, cefazolin, erythromycin, clindamycin, chloramphenicol, and sulfamethoxazole-trimethoprim. Of all the isolates, 48 (21.0%) showed intermediate resistance and 17 (7.4%) showed resistance to penicillin G. Penicillin-resistant strains had higher minimal inhibitory concentrations of ampicillin, mezlocillin, and cefazolin than did penicillin-susceptible strains. Resistance to erythromycin and clindamycin was rare (1.3 and 0.9%, respectively). Of the isolates, 8.7% were resistant to sulfamethoxazole-trimethoprim, and all were susceptible to chloramphenicol. Penicillin resistance was associated with 13 serotypes. Serotypes 14, 19F, 19A, and 23F were both highly prevalent and frequently penicillin resistant.     

Susceptibility of clinical isolates of Campylobacter pyloridis to 11 antimicrobial agents.

The activities of 11 antimicrobial agents, including two bismuth salts, against 70 strains of Campylobacter pyloridis isolated from gastric biopsy specimens were tested. The isolates were very susceptible to penicillin (the MIC for 90% of the strains tested [MIC90] was 0.03 microgram/ml), erythromycin, cefoxitin (MIC90, 0.12 microgram/ml), gentamicin, and ciprofloxacin (MIC90, 0.25 microgram/ml). The bismuth salts and nalidixic acid had moderate activity (MIC90, 16 to 64 micrograms/ml). Twenty percent of the isolates were resistant to metronidazole (MIC, greater than 1 micrograms/ml), and all were resistant to sulfamethoxazole and trimethoprim (MIC90, greater than 256 micrograms/ml).     

Antimicrobial sensitivity and plasmid-mediated tetracycline resistance in Campylobacter jejuni isolated in Bangladesh

The antimicrobial sensitivity of Campylobacter jejuni isolated in Bangladesh from patients with diarrhoea, asymptomatic carriers and domestic animals was performed. All isolates were sensitive to erythromycin, gentamicin, furazolidone and kanamycin. Seven percent isolates were resistant to tetracycline, 8% to nalidixic acid, 37% to ampicillin and 100% to sulfamethoxazole-trimethoprim and cephalothin. Tetracycline resistance was observed to be plasmid mediated. No plasmid band(s) coding for ampicillin, sulfamethoxazole-trimethoprim or cephalothin resistance were observed, possibly indicating chromosomally located resistance. No significant differences in the susceptibility patterns of C. jejuni isolated from the different sources was observed. However, 10 patients' isolates showed low molecular weight (2-3, 7 Mdaltons) plasmid band(s) which were completely absent in isolates from asymptomatic carriers and animals.     

Bacteriostatic and bactericidal activities of 24 antimicrobial agents against Campylobacter fetus subsp. jejuni.

The bacteriostatic and bactericidal activities of 24 antimicrobial agents were tested with the Dynatech MIC 2000 system against 86 strains of Campylobacter fetus subsp. jejuni from human sources. The penicillins (penicillin G, ampicillin, amoxycillin, carbenicillin) had poor activity. Ampicillin and amoxycillin were equally active. Cefotaxime revealed a rather good activity. Erythromycin, gentamicin, tobramycin, amikacin, and furazolidone were the most active compounds. Two strains (2.3%) were resistant to erythromycin. One strain (1.2%) was completely resistant to tobramycin. The tetracyclines (tetracyline, doxycycline, minocycline) were generally effective, but 8% of the strains were totally resistant to them. Minocycline was the most active. Chloramphenicol, thiamphenicol, and clindamycin had good activity. The bacteriostatic and bactericidal distributions for colistin, nalidixic acid, and metronidazole were broad.     

Antimicrobial resistance in Campylobacter strains isolated from French broilers before and after antimicrobial growth promoter bans

OBJECTIVES: The antimicrobial susceptibility of Campylobacter strains isolated from standard and free-range broilers in 1992-1996 and 2001-2002 was studied. METHODS: Strains were isolated from caeca or skin samples collected from standard or free-range broilers arriving in slaughterhouses. The MICs of ampicillin, nalidixic acid, enrofloxacin, tetracycline, erythromycin and gentamicin were determined by agar dilution and compared according to species (Campylobacter jejuni or Campylobacter coli), production system and sampling period. RESULTS: Results showed that all chickens harboured Campylobacter. An increase over time of the C. coli/C. jejuni ratio for standard chickens occurred. A wide range of MICs was observed among isolates from the same broiler or from the same farm. Strains collected on entry to the slaughterhouse and after storage showed no significant difference in their antibiotic resistance. C. coli was more resistant than C. jejuni to tetracycline and erythromycin during the first period and to all tested molecules (except gentamicin) during the second period. Strains isolated from standard chickens were also more often resistant than those isolated from free-range broilers. The percentage of C. jejuni strains resistant to ampicillin decreased from 1992-1996 to 2001-2002, whereas no change could be observed for the other antimicrobial agents. However, for C. coli the resistance to ampicillin, nalidixic acid, enrofloxacin, tetracycline and erythromycin significantly increased. CONCLUSION: There was an increase in the incidence of antibiotic resistance of C. coli between 1992-1996 and 2001-2002.     

空肠弯曲菌耐药谱特征分析

目的 分析十几年间我国空肠弯曲菌临床分离株对10种抗生素耐药谱特征,了解我国空肠弯曲菌耐药的变迁趋势。 方法 采用世界卫生组织(WHO)全球食源性病原菌感染网络(GFN)推荐的弯曲菌琼脂稀释法,测定1995年至今分离的116株空肠弯曲菌对6类10种抗生素的最小抑菌浓度(MIC)。 结果 经对实验结果整体分析,甲硝唑的总体耐药率最高为97.4%(113/116),四环素为82.8%(96/116),环丙沙星为80.2%(93/116),萘啶酸为79.3%(92/116),左氧氟沙星和氨苄西林耐药率相同,为40.5%(47/116),氯霉素为18.1%(21/116),庆大霉素为8.6%(10/116),链霉素为4.3%(5/116),最低为红霉素0(0/116)。随着时间的推进,萘啶酸、环丙沙星、左氧氟沙星和氨苄西林的MIC有明显增高趋势;四环素、红霉素、庆大霉素、氯霉素和甲硝唑的MIC值变化不明显;链霉素的MIC值变化有下降的趋势。6.1%的菌株出现了8种抗生素多重耐药的结果,且菌株均出现在2010年后。经统计学分析,萘啶酸、环丙沙星、链霉素、庆大霉素、氯霉素和氨苄西林6种抗生素在2001年前、2001-2005年、2006-2010年和2010年后4个时间段中耐药率差异有统计学意义。 结论 空肠弯曲菌对红霉素、庆大霉素以及链霉素3种抗生素依旧保持了较高的敏感性,对萘啶酸、环丙沙星、左氧氟沙星、四环素、甲硝唑以及氨苄西林6种抗生素产生了较大程度的耐药。     

Penicillin tolerance of human isolates of group C streptococci.

Seventeen clinical isolates of group C streptococci were tested for penicillin tolerance. Sixteen of the strains showed penicillin tolerance with a 32-fold or greater difference between the minimal inhibitory concentration and the minimal bactericidal concentration. Synergism was demonstrated with a combination of penicillin and gentamicin for all 17 strains tested. The rate of antibiotic killing was measured for five of the streptococcal strains by using the combination of penicillin and gentamicin. All isolates were killed within 5 h with the combination, but viable organisms were recovered after 48 h when either drug was used alone. Our study suggests that penicillin tolerance with group C streptococci may occur frequently and may account for the poor outcome of serious group C streptococcal infections tested with penicillin alone.     

Comparison of antimicrobial susceptibility patterns of fifty-seven strains of Haemophilus ducreyi isolated in Amsterdam from 1978 to 1985

The in-vitro activities of 16 antimicrobial agents were tested against 57 strains of Haemophilus ducreyi isolated in Amsterdam during an eight year period. The susceptibility patterns of the isolates from different years were compared. In the first four years more than 30% were beta-lactamase negative and showed MICs for tetracycline of 2 mg/l or less. From 1982 to 1985 all strains, except one, produced beta-lactamase and were tetracycline resistant. Furthermore, MICs for cefotaxime, sulphamethoxazole and trimethoprim increased. No changes were seen with cephradine, erythromycin, kanamycin, gentamicin, chloramphenicol, nalidixic acid, pipemidic acid, norfloxacin, pefloxacin or ciprofloxacin.     

Susceptibilities to 10 antimicrobial agents of 1,220 Campylobacter strains isolated from 1987 to 1993 from feces of pediatric patients.

We report the in vitro antibiotic susceptibility of 1,220 strains belonging to the thermotolerant Campylobacter species, isolated from the feces of pediatric patients with diarrhea in the period from 1987 to 1993. The strains were identified as 1,148 C. jejuni isolates and 72 C. coli isolates. The overall results show that the strains showed drug resistance as follows: 51.8% to ampicillin, 4.4% to clindamycin, 2.6% to chloramphenicol, 21.2% to tetracycline, and 1% to gentamicin. Twenty-one strains (1.7%) displayed resistance to the combination of amoxicillin-clavulanic acid, and 3.2% of the strains were resistant to erythromycin (MIC of > or = 4 micrograms/ml), with a notable difference according to the species under consideration. While C. jejuni remained stable at 0.9 to 4% resistance to erythromycin, for C. coli the percentages detected ranged from 0 to 33%, with overall rates of 2.5 and 15.2% for the two species, respectively. Resistance to nalidixic acid (MIC of > or = 32 micrograms/ml) was found in 27.2% of the strains (27.8% for C. jejuni and 18% for C. coli), and resistance to ciprofloxacin (MIC of > or = 4 micrograms/ml) was found in 24.2% of the strains for C. jejuni and 15.2% for C. coli). Cross-resistance between nalidixic acid and ciprofloxacin was found in 89.1% of the strains (type 1 mutants), while 10.9% were resistant to nalidixic acid but susceptible to ciprofloxacin (type 2 mutants).     

Botulinum toxin

Botulinum toxin is regarded as the most lethal substance known. It is estimated that the human LD50 for inhalation botulism is 1 to 3 nanograms of toxin/kilogram body mass. Although only three cases of inhalational botulism have been described, an understanding of the pathophysiology of food-borne outbreaks, wound botulism, and infant botulism, and their therapies, enables the medical community to plan treatment in the event of an aerosol release of botulinum toxin. Antitoxin, vaccine, and F(ab')2 immune fragment therapies are discussed as adjuncts to supportive therapy.     

49株脑膜炎奈瑟菌体外抗菌药物敏感性检测

目的 了解2005-2006年中国脑膜奈瑟菌分离株(Neisseria meningitides,Nm)的抗菌药物敏感性变化趋势,为选择抗菌药物对流行性脑脊髓膜炎(流脑)患者进行治疗提供参考.方法 采用肉汤稀释检测最低抑菌浓度(MICs)方法、药敏纸片扩散(K-)法和E-test试纸条检测方法对本实验室收集的49株(16株A群、33株C群)2005-2006年分离的患者Nm菌株进行体外抗菌药物敏感性检测.结果 16株A群Nm菌株对复方新诺明、四环素、左氧氟沙星、萘啶酸4种抗菌药物耐药,对环丙沙星耐药或中度敏感.33株C群Nm菌株对复方新诺明耐药,31株(93.9%)C群菌株对萘啶酸耐 药,20株(60.6%)C群菌株对左氧氟沙星耐药,17株(51.5%)C群菌株对环丙沙星耐药.分别发现对青霉素不敏感的4株A群和1株C群Nm菌株.结论 2005-2006年,中国的A群和C群Nm菌株对磺胺类药物和喹诺酮类药物普遍耐药,此两类药物不适合中国流脑的临床用药及人群预防性给药.K-药敏纸片和肉汤稀释MICs及E-test方法具有较高的一致性.     

2003-2012年中国部分地区脑膜炎奈瑟菌体外抗生素敏感性分析

目的 了解我国脑膜炎奈瑟菌对抗生素敏感性的变化趋势. 方法 对2003-2012年本研究室收集的脑膜炎奈瑟菌菌株,根据分离年份、血清群和来源(患者或健康携带者)选择487株,采用微量肉汤稀释法和E-test浓度梯度扩散法,对其进行体外12种抗生素敏感性检测和分析. 结果 所有菌株对头孢噻肟、头孢曲松、阿奇霉素、美洛培南、氯霉素和米诺环素均敏感;对青霉素和氨苄西林不敏感的菌株分别是4.9%(24/487)和3.5%(17/487),75.6%(368/487)的菌株对萘啶酸耐药,87.1%(424/487)对复方新诺明耐药,48.9%(238/487)对环丙沙星耐药.从2005年开始出现对环丙沙星耐药的菌株23.8%(24/101),从2006年开始出现对青霉素类药物不敏感菌株2.4%(2/82).患者和健康携带者来源的菌株对萘啶酸、复方新诺明和环丙沙星3种药物显现不同的耐药率. 结论 我国流脑菌株对磺胺类和喹诺酮类药物具有较高的耐药性,对青霉素类药物不敏感的菌株也逐渐增多.这种耐药性与菌株分离年份、血清群和菌株来源具有相关性.     

Comparison of the Etest and agar dilution for in vitro antimicrobial susceptibility testing of Campylobacter

The performance of the Etest and agar dilution for in vitro antimicrobial susceptibility of Campylobacter spp. was evaluated using a quality control strain Campylobactor jejuni ATCC 33560, and 81 C. jejuni and 54 Campylobacter coli isolates recovered from retail raw meats. Seven antimicrobial agents: chloramphenicol, ciprofloxacin, doxycycline, erythromycin, gentamicin, nalidixic acid and tetracycline, were tested using the two methods, whereas azithromycin was tested using the Etest only. The correlation between the Etest and agar dilution MICs varied greatly depending on the antimicrobial agents tested. The overall agreement of MICs (+/-1 log(2) dilution) between the two methods was 61.9%, ranging from 21.4% for nalidixic acid to 92.6% for gentamicin. MICs obtained using the Etest were generally lower than those by agar dilution regardless of the species of organism tested. MIC(50) and/or MIC(90) values were at least one dilution lower for the Etest than for agar dilution when testing chloramphenicol, ciprofloxacin, doxycycline, erythromycin and nalidixic acid. Based on the agar dilution MICs, the resistant rate of the 135 Campylobacter isolates was highest for tetracycline (82.2%), followed by doxycycline (78.5%), nalidixic acid (21.5%), ciprofloxacin (20.7%) and erythromycin (17.0%). None of the isolates demonstrated resistance to chloramphenicol or gentamicin. The study indicated that the Etest results were not in complete agreement with the agar dilution test. Although the Etest has been proven to be a satisfactory testing method, its use for Campylobacter susceptibility testing requires further standardization. The study also showed that C. jejuni and C. coli isolates resistant to antimicrobials used for treating campylobacteriosis were common in retail raw meats.     

Bactericidal activity of netilmicin compared with gentamicin and streptomycin, alone and in combination with penicillin, against penicillin tolerant viridans streptococci and enterococci

Netilmicin was compared with gentamicin and streptomycin for in-vitro activity against 30 strains of penicillin-tolerant streptococci including 16 strains of enterococci. Both netilmicin and gentamicin tested alone at 4 mg/l caused 99.9% kill of more than half of the 13 strains of viridans streptococci tested, whereas streptomycin, 4 mg/l, had no bactericidal effect against these strains. Netilmicin, gentamicin and streptomycin tested alone at 8.0 mg/l against 10 strains of Streptococcus faecalis resulted in 99.9% kill of six, one and zero strains respectively. Combinations of penicillin with 2 mg/l of either netilmicin or gentamicin resulted in bactericidal synergy against 12 of 13 strains of viridans streptococci and all 10 strains of S. faecalis after 18 to 24 h incubation. Parallel experiments showed that higher concentration of penicillin were required to obtain 99.9% kill of 10 streptococcal strains when 4 mg/l streptomycin was compared with 2 mg/l of the other aminoglycosides. Killing curves showed similar bactericidal synergy for netilmicin-penicillin and gentamicin-penicillin combinations against most streptococci tested after 24 h incubation but there was sometimes a greater bactericidal effect noted with netilmicin after only 6 h incubation of the broth or after 48 h incubation. The results of this in-vitro study suggest that netilmicin is at least as effective as gentamicin as a bactericidal synergic agent with penicillin against penicillin-tolerant viridans streptococci and S. faecalis strains isolated from patients with endocarditis. Neither gentamicin or netilmicin were effective as bactericidal synergic agents with penicillin against 4 of 6 strains of S. faecium tested.     

一例婴儿B型肉毒中毒的实验室诊断

目的对2019年2月来自北京儿童医院1例疑似肉毒中毒的婴儿粪便样品进行实验室诊断，判定是否为肉毒毒素中毒。方法按照GB 4789.12 — 2016稀释处理样品，利用动物实验鉴定肉毒毒素、接种增菌培养基观察变化、采用卵黄培养基进行分离纯化，扩增测序16S rRNA基因并进行序列比对，采用荧光定量PCR方法进行毒素基因分型。结果粪便样本稀释后对小鼠进行腹腔注射，小鼠出现呼吸急促、腹式呼吸，并在4～6 h内死亡，呈现肉毒中毒典型症状。 在卵黄培养基平板上分离到典型肉毒梭菌，镜检观察到芽孢形态，测得的16S rRNA基因序列与GenBank中公开的肉毒梭菌16S rRNA基因序列进行比对，相似率>99%，荧光定量PCR检测显示B型毒素基因阳性，判定该婴儿为B型肉毒中毒。结论此次实验按照国家标准和本实验室建立的荧光定量PCR方法进行鉴定，检测结果和诊断方案为我国婴儿B型肉毒中毒诊断提供参考，也为分析肉毒中毒地域性提供证据，为临床鉴定婴儿B型肉毒中毒提供参考案例。     

Antibiotic Susceptibility of Haemophilus vaginalis (Corynebacterium vaginale) to 21 Antibiotics

A total of 56 strains of Haemophilus vaginalis were tested for their in vitro susceptibility to 21 antimicrobial agents by an agar dilution method. All strains were inhibited by 1 mug or less of penicillin, ampicillin, carbenicillin, and vancomycin per ml. The cephalosporins were less active; 4 mug of cefazolin per ml, 16 mug of cephalothin per ml, or 128 mug of cephalexin per ml was required to inhibit all strains. Kanamycin, gentamicin, tobramycin, and neomycin were relatively inactive against H. vaginalis. All strains were inhibited by 4 mug of streptomycin per ml and 2 mug of chloramphenicol per ml. Only 57% of the strains were inhibited by 4 mug of tetracycline per ml, whereas 43% were inhibited by 16 to 64 mug/ml. The combination sulfamethoxazole/trimethoprim was relatively inactive against H. vaginalis. All strains tested exhibited minimal inhibitory concentrations of >/=128 mug when tested against colistin, nalidixic acid, and sulfadiazine. Erythromycin and clindamycin were the most active of the antibiotics tested; for all strains the minimal inhibitory concentrations were 相似文献