Antibiotic resistance and serotypes of Streptococcus pneumoniae from patients with community-acquired pneumococcal disease.

From August 1978 to December 1981, 200 Streptococcus pneumoniae strains isolated from adult patients with pneumococcal disease were tested for susceptibility to penicillin G, erythromycin, clindamycin, tetracycline, and chloramphenicol by disk diffusion. Minimal inhibitory concentrations (MICs) were determined by agar dilution and broth dilution. The sources (numbers) of these isolates were blood (111), cerebrospinal fluid (30), sputum (26), pleural fluid (16), and miscellaneous (17). Of the 200 strains, 18 were partially resistant (MIC, 0.1 to 1 micrograms/ml) and 2 were resistant to penicillin. A total of 144 (72%) strains were tetracycline resistant, 87 of which had MICs of greater than or equal to 64 micrograms/ml. Ninety (45%) isolates exhibited various degrees of chloramphenicol resistance, with MICs ranging from 16 to 64 micrograms/ml. Five strains were resistant to erythromycin and clindamycin. Eleven penicillin-resistant strains were also resistant to chloramphenicol and tetracycline. Twenty-one different serotypes were encountered among the 120 typed strains studied. The most prevalent serotypes, in order of frequency, were 3, 1, 5, 19, 8, 6, 9, and 4, representing approximately two-thirds of the total number of isolates serotyped. These findings clearly indicate the need to perform antibiotic susceptibility testing in all cerebrospinal fluid isolates and other clinical significant isolates.     

Susceptibility of Clostridium botulinum to thirteen antimicrobial agents.

A total of 224 strains of Clostridium botulinum (including isolates from 14 patients with infant botulism and 4 with wound botulism) and 15 strains of C. sporogenes were tested by agar dilution for susceptibility to tetracycline, metronidazole, erythromycin, penicillin, rifampin, chloramphenicol, clindamycin, cephalothin, cefoxitin, vancomycin, sulfamethoxazole-trimethoprim, nalidixic acid, and gentamicin. At least 90% of the C. botulinum strains tested (except for nonproteolytic strains of toxin type F with penicillin) were susceptible to all drugs except sulfamethoxazole-trimethoprim, nalidixic acid, and gentamicin. Minimal inhibitory concentrations for strains from patients with infant and wound botulism were similar to those for other C. botulinum strains.     

In Vitro Activity of Antimicrobial Agents on Legionnaires Disease Bacterium

Six isolates of Legionnaires disease bacteria were tested for their susceptibility to 22 antimicrobial agents. The most active agent was rifampin (minimal inhibitory concentration, 相似文献   

Tetracycline resistance of Corynebacterium diphtheriae isolated from diphtheria patients in Jakarta, Indonesia

Of 133 Corynebacterium diphtheriae isolates from diphtheria patients in Jakarta, Indonesia, 86% were resistant to greater than or equal to 32 micrograms of tetracycline per ml. All isolates were sensitive to ampicillin, cephalothin, chloramphenicol, clindamycin, penicillin, erythromycin, and kanamycin. The general resistance of C. diphtheriae to tetracycline in this part of Indonesia appears to be unique compared with resistance reported in studies done in other parts of the world.     

安徽省铜陵地区2010年细菌耐药性监测

目的了解安徽省铜陵地区2010年临床分离菌株耐药状况。方法 2010年1—12月铜陵地区临床分离菌株用纸片法(Kirby-Bauer)作药敏试验。结果此期获得的2 217株细菌中革兰阳性菌498株,占22.5%;革兰阴性菌1 719株,占77.5%;MRSA和MRCNS分别占金葡菌和凝固酶阴性葡萄球菌的34.8%和75.1%;MRSA和MRCNS对庆大霉素、环丙沙星、克林霉素和红霉素等均高度耐药,未见耐万古霉素和替考拉宁葡萄球菌;粪肠球菌对青霉素、氨苄西林、呋喃妥因、磷霉素和氯霉素的耐药率较低;屎肠球菌对磷霉素和氯霉素耐药率较低,未见耐万古霉素和替考拉宁肠球菌。大肠埃希菌和克雷伯菌属中产ESBLs株分别占53.2%和39.9%,产ESBLs株除对亚胺培南和美罗培南均无耐药株外,对其他19种抗菌药物的耐药率均较非产ESBLs株高;不发酵糖革兰阴性杆菌对常用抗菌药物的耐药率较往年上升。结论未发现对糖肽类抗生素耐药的葡萄球菌属菌株;肠杆菌科细菌对亚胺培南、美罗培南、头孢哌酮-舒巴坦、哌拉西林-他唑巴坦和阿米卡星耐药率低;不发酵糖革兰阴性杆菌对常用抗菌药物的耐药率较往年上升,应加强抗菌药物的合理使用和医院感染控制。     

Antimicrobial resistance of Streptococcus pneumoniae isolated in Taiwan: an island-wide surveillance study between 1996 and 1997

Between August 1996 and July 1997, 550 clinically significant Streptococcus pneumoniae isolates were collected from 14 geographically separate laboratories in Taiwan. These isolates were serotyped and MICs were determined by agar dilution. Among serotypes covered by the 23-valent vaccine, types 19F, 19A, 23F, 23A and 6B dominated, comprising 255 isolates; among non-vaccine serotypes, types 35, 39, 34, 13 and 31 dominated, comprising 118 isolates. Of the 550 isolates, 310 (56.4%) were resistant to penicillin G (MIC 0. 12 mg/L), 238 (43.3%) with intermediate resistance (MIC 0.12-1 mg/L) and 72 (13.1%) with high-level resistance (MIC 2 mg/L). Most non-susceptible pneumococci were of serotypes 19F and 23F; non-susceptible isolates of these serotypes were distributed across all of Taiwan. Fourteen other antibiotics were tested; 83% of the isolates were resistant to tetracycline, 78% to azithromycin, 74% to erythromycin, 54% to clindamycin and 23% to chloramphenicol. Thus, macrolides can no longer be used as first line agents to treat pneumococcal infections in Taiwan. Multi-resistance (isolates resistant to three or more chemically unrelated antibiotics) was found in each serotype or group, but mostly in types 19F and 23F. The emergence of such strains complicates antibiotic selection, but both types are covered by the 23-valent vaccine, as were 82% of the isolates from blood and eight of the nine from cerebrospinal fluid. Good antibiotic control and appropriate use of this vaccine may improve the current problem in Taiwan, especially for the elderly.     

In vitro susceptibilities of Campylobacter-like organisms to twenty antimicrobial agents.

We determined MICs of 20 antimicrobial agents for 50 representative strains of four subgroups of Campylobacter-like organisms (CLOs) by agar dilution. Ampicillin, gentamicin, doxycycline, tetracycline, ceftriaxone, rifampin, spectinomycin, nalidixic acid, and chloramphenicol were active against all strains of CLOs. Most CLO strains (83%) were inhibited by 4 micrograms of sulfamethoxazole per ml and by 8 micrograms of trimethoprim-sulfamethoxazole per ml. Of type 1 strains, 28% were resistant to 8 micrograms of erythromycin per ml. In addition, cross resistance between erythromycin and clindamycin was always present. Type 1 strains exhibited a broad distribution of MICs of metronidazole and streptomycin, whereas all type 2 strains were uniformly susceptible to metronidazole and resistant to streptomycin. Unlike type 1 and 3 strains, type 2 CLOs were susceptible to cephalothin and penicillin G and highly resistant to streptomycin. The type 3 strain was uniquely resistant to cefazolin. The majority of strains were not inhibited by cefoperazone; and all were resistant to trimethoprim. In contrast to Campylobacter jejuni and Campylobacter fetus subsp. fetus, all CLOs tested were susceptible to 0.5 microgram of rifampin per ml.     

Antimicrobial Susceptibility Testing of Pneumococci: Determination of Kirby-Bauer Breakpoints for Penicillin G, Erythromycin, Clindamycin, Tetracycline, Chloramphenicol, and Rifampin

Antimicrobial susceptibility testing of pneumococci is now essential to monitor for the presence of resistance to agents such as the penicillins, macrolides, lincomycins, chloramphenicol, and tetracycline. In this study, clinical isolates of a selection of resistant South African strains were tested for antimicrobial susceptibility by minimal inhibitory concentration (MIC) determination and by a modified Kirby-Bauer disk diffusion technique, using Mueller-Hinton medium supplemented with 5% horse blood. Disk diffusion breakpoints were determined for penicillin G, erythromycin, clindamycin, tetracycline, chloramphenicol, and rifampin. Reliable results were obtained on disk diffusion for all these agents except for penicillin G. With 6-mug penicillin G disks, zones of strains with intermediate penicillin susceptibility overlapped those of sensitive and resistant strains. With 5-mug methicillin disks, clearer separation of strains based on susceptibility to penicillin G occurred. Strains with zones of <35 mm around penicillin G disks and <25 mm around methicillin disks should have penicillin G MICs determined to confirm their resistance to penicillin G. In view of the potential for pneumococci to be resistant to the agents used in this study, antimicrobial susceptibility of all clinically significant isolates should be determined.     

Antimicrobial resistance of Streptococcus pneumoniae isolates of outpatients in Germany, 1999-2000

BACKGROUND: The aim of the study was to determine the prevalence of antimicrobial resistance among clinical isolates of Streptococcus pneumoniae during the winter of 1999-2000 in Germany. METHODS: Pneumococcal isolates were prospectively collected by 14 different clinical microbiology laboratories. Minimal inhibitory concentrations of penicillin G, erythromycin A, clarithromycin, roxithromycin, azithromycin, clindamycin, levofloxacin and telithromycin were determined by the broth microdilution method. RESULTS: Among 328 strains 4.6% were nonsusceptible to penicillin G (intermediate and resistant strains) and 9.5% were resistant to erythromycin A. Analysis of erythromycin-resistant strains for the underlying resistance determinants revealed that 12 (38.7%) belonged to the erm(B) and 19 (61.3%) to the mef(E) type of resistance. Among the macrolide-resistant strains, serotypes 19F (n = 9) and 14 (n = 8) were the predominant types. CONCLUSIONS: Macrolide resistance in Germany is of growing concern and mainly due to the high prevalence of pneumococci expressing the mef(E) type of resistance.     

Prevalence and Mechanisms of Macrolide Resistance in Clinical Isolates of Group A Streptococci from Ontario, Canada

A total of 3,205 group A streptoccal isolates were collected in 1997 through a private laboratory which serves community physicians in southern Ontario and which represents a population base of 6 million people. Nonsusceptibility to erythromycin was detected for 67 (2.1%) isolates both by disk diffusion and by broth microdilution. Of these, 47 (70%) were susceptible to clindamycin and were found by PCR to possess the mef gene. Of the other 20 strains, 18 and 2 showed inducible and constitutive resistance, respectively, to clindamycin. Nineteen of these strains were shown by PCR to possess the ermTR gene, and a single constitutively resistant strain harbored an ermB gene. Sixteen (24%) erythromycin-resistant strains were also resistant to tetracycline. All were susceptible to penicillin and chloramphenicol.     

葡萄球菌属对抗菌药物的耐药性分析

目的了解葡萄球菌属临床分离株的耐药性及对大环内酯类、林可霉素类及链阳霉素类（MLS）的耐药表型。方法用Kirby-Bauer法测定葡萄球菌属对14种抗菌药的敏感性，进行D试验测定MLS耐药表型。结果在230株葡萄球菌属中，耐甲氧西林金葡菌（MRSA）和耐甲氧西林凝固酶阴性葡萄球菌（MRSCN）分别为9．9％和79．8％。对青霉素都呈现高度耐药。未发现万古霉素及替考拉宁耐药菌株，126株葡萄球菌属对红霉素耐药，54．8％（23／42）株金葡菌为结构型耐药；在凝固酶阴性葡萄球菌中（CNS），44．0％（37／84）为结构型耐药，41．7％（35／84）为外排型耐药。对红霉素耐药但对克林霉素敏感的葡萄球菌中，17株为诱导型克林霉素耐药。结论应加强对葡萄球菌的耐药性监测，临床微生物实验室应进行D试验。指导临床合理使用抗生素。     

Prevalence and Mechanisms of Macrolide Resistance in Invasive and Noninvasive Group B Streptococcus Isolates from Ontario, Canada

Macrolide resistance has been demonstrated in group B streptococcus (GBS), but there is limited information regarding mechanisms of resistance and their prevalence. We determined these in GBS obtained from neonatal blood cultures and vaginal swabs from pregnant women. Of 178 isolates from cases of neonatal GBS sepsis collected from 1995 to 1998, 8 and 4.5% were resistant to erythromycin and clindamycin, respectively, and one isolate showed intermediate penicillin resistance (MIC, 0.25 microg/ml). Of 101 consecutive vaginal or rectal/vaginal isolates collected in 1999, 18 and 8% were resistant to erythromycin and clindamycin, respectively. Tetracycline resistance was high (>80%) among both groups of isolates. Of 32 erythromycin-resistant isolates, 28 possessed the erm methylase gene (7 ermB and 21 ermTR/ermA) and 4 harbored the mefA gene; one isolate harbored both genes. One isolate which was susceptible to erythromycin but resistant to clindamycin (MIC, 4 microg/ml) was found to have the linB gene, previously identified only in Enterococcus faecium. The mreA gene was found in all the erythromycin-resistant strains as well as in 10 erythromycin-susceptible strains. The rate of erythromycin resistance increased from 5% in 1995-96 to 13% in 1998-99, which coincided with an increase in macrolide usage during that time.     

Correlation between serogroup and susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline among 308 isolates of Clostridium difficile

The susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline of 308 isolates of Clostridium difficile from various origins was determined by a disc diffusion susceptibility testing and the results were compared with the serogroup of the strains. For the five antimicrobials, there was a clear-cut separation between susceptible and resistant strains. Some correlation between resistance and serogroup was found. Almost all of the 161 isolates of serogroups A, F, G, H and X were susceptible to all antibiotics. The 32 toxigenic isolates of serogroup C were characterized by a typical resistance pattern which could be used for typing purposes. Other serogroups showed variable patterns. The review of 64 cases of antibiotic associated diarrhoea showed that these differences in susceptibility could have clinical implications: all seven cases due to clindamycin were caused by a clindamycin resistant strain of serogroup C, whereas cases associated with other antibiotics were distributed among various serogroups.     

Incidence of erythromycin resistance in Streptococcus pyogenes: a 10-year study

We studied the evolution of susceptibility of Streptococcus pyogenes isolated in our hospital from 1987 to 1996. Susceptibility to penicillin, ampicillin, cefotaxime, cefuroxime, imipenem, erythromycin, clindamycin, tetracycline, vancomycin, ciprofloxacin, rifampin, and chloramphenicol was determined by the National Committee for Clinical Laboratory Standards broth microdilution method. Differentiation of phenotypes of erythromycin-resistant strains was performed using the double-disc method. All isolates remained very susceptible in vitro to penicillin and all of the other beta-lactam agents tested. Between 1987 and 1995 the incidence of erythromycin resistant strains remained below 5%; the difference in the resistance rate between 1995 (2.6%) and 1996 (17.1%) was statistically significant. The macrolide resistance M phenotype was the most frequent. The isolation rates of tetracycline-resistant strains increased from 2.2% in 1987 to 11.2% in 1988. The marked increase in the incidence of erythromycin resistance observed in our area warrants periodic surveillance of antibiotic susceptibility of S. pyogenes isolates and emphasizes the need to control outpatient antibiotics. The preponderance of the M phenotype may have implications in the choice of antibiotic.     

Antimicrobial susceptibility of 103 strains of Haemophilus ducreyi isolated in Johannesburg.

Of 103 strains of Haemophilus ducreyi isolated in Johannesburg, 96 produced beta-lactamase and were resistant to penicillin and ampicillin. Most strains showed resistance to tetracycline, sulfisoxazole, and sulfamethoxazole. All isolates were susceptible to rifampin, erythromycin, and cefoxitin, moderately susceptible to trimethoprim-sulfamethoxazole (1:19) and minocycline, and somewhat less susceptible to doxycycline.     

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae isolates from pediatric patients in Singapore

One hundred eighty Streptococcus pneumoniae strains isolated from children at a pediatric hospital in Singapore from 1997 to 1999 were serotyped and their antimicrobial susceptibility patterns were determined. Sixty-three percent of the isolates were resistant to penicillin. Significantly large numbers of the strains investigated were resistant to trimethoprim-sulfamethoxazole (87.8%), tetracycline (71.7%), erythromycin (67.8%), and chloramphenicol (40%). Penicillin and multidrug resistance was mostly associated with the frequently isolated S. pneumoniae isolates of serotypes (serotypes 19F, 23F, 6B, and 14). Isolates of serotype 19F, the serotype most commonly encountered in Singapore (41.1%), had the highest prevalence of penicillin (78.4%) and multidrug resistance (94.6%). Most of the invasive S. pneumoniae isolates (8 of 17; 47. 1%) were of serotype 14.     

Antimicrobial susceptibility of Campylobacter jejuni with special reference to resistance patterns of Canadian isolates.

Agar dilution antimicrobial susceptibility testing of Camphylobacter jejuni showed that erythromycin, clindamycin, nitrofurantoin, and gentamicin were the most active compounds, inhibiting 90% of the isolates at a concentration of 1 microgram/ml or less. The frequency of high-level erythromycin resistance was 1%. Erythromycin-resistant isolates showed cross-resistance to clindamycin. All strains were inhibited by chloramphenicol at less than or equal to 8 micrograms/ml. About 20% of the isolates were resistant to tetracycline at 4 micrograms/ml. All strains were highly resistant to novobiocin, bacitracin, vancomycin, and trimethoprim and resistant to rifampin. The minimal inhibitory concentrations (MICs) of metronidazole ranged from less than or equal to 0.5 to 128 micrograms/ml. The susceptibility of strains to sulfamethoxazole and polymyxin B sulfate was markedly influenced by inoculum size. The MICs of polymyxin B sulfate were significantly higher at 42 than 36 degrees C. All strains were inhibited by nalidixic acid at 32 micrograms/ml. In the penicillin group, ampicillin was the most active compound, inhibiting only about three-quarters of the strains at 8 micrograms/ml. The cephalosporins as a group showed only moderate to poor activity, the most active cephalosporin being cefotaxime, which inhibited about 90% of the strains at 8 micrograms/ml. The use of antibiotics in selective media is discussed.     

Antimicrobial resistance among respiratory isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae in the United States.

A national surveillance study was conducted to determine trends in antimicrobial resistance patterns among three common causes of community-acquired respiratory tract infections. Fifteen participating U.S. medical centers submitted clinically significant isolates of Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, and Streptococcus pneumoniae to two central laboratories for testing with a group of 12 antimicrobial agents. The majority of isolates were recovered from adult males greater than 50 years old. Overall, 84.1% of 378 M. catarrhalis and 16.5% of 564 H. influenzae (29.5% of type b strains; 15.0% of non-type b strains) produced beta-lactamase and were thus resistant to penicillin, ampicillin, and amoxicillin. Resistance in H. influenzae to other agents was 2.1% to tetracycline, 0.7% to trimethoprim-sulfamethoxazole, 1.1% to cefaclor, and 0.2% to cefuroxime and amoxicillin-clavulanate, while the M. catarrhalis isolates yielded very low MICs of these latter drugs. As demonstrated in prior studies, erythromycin showed little activity against H. influenzae. Of 487 S. pneumoniae isolates, 1 (0.2%) was penicillin resistant, while 3.8% were relatively resistant to penicillin, 4.5% were resistant to trimethoprim-sulfamethoxazole, 2.3% were resistant to tetracycline, 1.2% were resistant to chloramphenicol, and 0.2% were resistant to erythromycin. Overall, the lowest resistance rates for these common bacterial respiratory pathogens were noted with amoxicillin-clavulanate, cefuroxime, and cefaclor.     

Serogroup specificity and antimicrobial susceptibilities of Neisseria gonorrhoeae isolated in Mexico City

The serogroup pattern of 87 clinical isolates of Neisseria gonorrhoeae was determined by monoclonal coagglutination and the in-vitro activity of seven antimicrobial agents against the same strains was tested by an agar dilution method. The frequency of resistance to spectinomycin, ampicillin, penicillin, erythromycin, chloramphenicol and tetracycline was 14.9%, 33.3%, 34.4%, 30%, 40.2% and 41.3%, respectively. All strains were susceptible to cefotaxime. Out of 87 strains tested, 29.8% produced beta-lactamases and 4.5% were chromosomally resistant to penicillin. In all instances resistance to a drug was associated with serogroup 1-B except for erythromycin. The results presented here correlate with observations made worldwide.     

肺炎链球菌对红霉素耐药机制的研究

目的 研究北京地区肺炎链球菌对红霉素的耐药机制。方法 收集本院1998－1999年分离的对红霉素耐药的肺炎链球菌116株,采用“荚膜肿胀”技术进行血清分型,聚合酶链反应（PCR）检测对红霉素耐药的基因erm/mef,脉冲场凝胶电泳（PFGE)客青霉素结合蛋白（PBP）基因印迹技术追踪菌株之间的同源性。结果 116株红霉素耐药株的血清型主要为23F（30.0%),6A（19.0%),19F（13.8%),15（7.8%),23A（5.2%)。95.7%的青霉素不敏感株同时也耐红霉素;85％的菌株表现为MLS表型,即同时耐克林霉素;86．4％的红霉素耐药株具有erm基因,6％的菌株同时有erm和mef基因,1．7％的菌株只有mef基因,4．2％未能检测到erm或mef基因。PFGE发现2种耐药克隆：1个是青霉素耐药的血清型为23F的克隆株,另1个是青霉素敏感而红霉素耐药的、血清型为6A的克隆株。结论 核糖体突变（erm基因编码）是北京地区肺炎链球菌耐红霉素的主要机制,2种耐药克隆值得关注。