Antibiotic resistance in respiratory tract isolates of Haemophilus influenzae and Moraxella catarrhalis collected from across Canada in 1997-1998

Between September 1997 and November 1998 respiratory tract isolates of Haemophilus influenzae (n = 1352) and Moraxella catarrhalis (n = 428) were collected by 18 Canadian medical centres. beta-Lactamase was produced by 24.0 and 94.2% of H. influenzae and M. catarrhalis isolates, respectively. Resistance rates for H. influenzae were highest for ampicillin (24.0%), trimethoprim/sulphamethoxazole (13. 7%), loracarbef (6.1%) and cefaclor (4.2%), and 相似文献   

Antibiotic resistance among recent clinical isolates of Haemophilus influenzae in Japanese children

From January 1997 to July 1999, a total of 867 isolates of Haemophilus influenzae were recovered in the microbiology laboratory of Chiba Children's Hospital. The overall prevalence of beta-lactamase production was 12.8%. Ampicillin-MICs for all of the 111 beta-lactamase-producing isolates was > or =4 microg/ml. A total of 26 beta-lactamase-negative isolates (3.4% of all beta-lactamase-negative isolates and 3.0% of all isolates) were found to be resistant to ampicillin. The prevalence of beta-lactamase negative ampicillin-resistant strains (BLNAR) increased remarkably to 8.9% during the last 7-month period. It is noteworthy that the MICs not only of penicillins but also of cephems for BLNAR were significantly higher than those for ampicillin-susceptible isolates. Eight beta-lactamase-producing isolates of H. influenzae (7.2% of all beta-lactamase-producing isolates) were resistant to amoxicillin-clavulanate (AMPC/CVA). Consequently, the overall resistance to ampicillin was 15.8%, and that to AMPC/CVA was 3.0%. The results of this study corroborate the findings of previous investigators in the US (Doern et al., 1997) regarding the emergence of BLNAR and beta-lactamase-producing AMPC/CVA-resistant strains (BLPACR) of H. influenzae. Continued monitoring of susceptibility trends will be required to guide appropriate chemotherapy.     

Genetic and molecular characterization of beta-lactamase-negative ampicillin-resistant Haemophilus influenzae with unusually high resistance to ampicillin

Previous studies with beta-lactamase-negative, ampicillin-resistant (BLNAR) Haemophilus influenzae from Japan, France, and North America indicate that mutations in ftsI encoding PBP3 confer ampicillin MICs of 1 to 4 micro g/ml. Several BLNAR strains with ampicillin MICs of 4 to 16 micro g/ml recently isolated from North America were studied. Pulsed-field gel electrophoresis identified 12 unique BLNAR strains; sequencing of their ftsI transpeptidase domains identified 1 group I and 11 group II mutants, as designated previously (K. Ubukata, Y. Shibasaki, K. Yamamoto, N. Chiba, K. Hasegawa, Y. Takeuchi, K. Sunakawa, M. Inoue, and M. Konno, Antimicrob. Agents Chemother. 45:1693-1699, 2001). Geometric mean ampicillin MICs for several clinical isolates were 8 to 10.56 micro g/ml. Replacement of the ftsI gene in H. influenzae Rd with the intact ftsI from several clinical isolates resulted in integrants with typical BLNAR geometric mean ampicillin MICs of 1.7 to 2.2 micro g/ml. Cloning and purification of His-tagged PBP3 from three clinical BLNAR strains showed significantly reduced Bocillin binding compared to that of PBP3 from strain Rd. Based on these data, changes in PBP3 alone could not account for the high ampicillin MICs observed for these BLNAR isolates. In an effort to determine the presence of additional mechanism(s) of ampicillin resistance, sequencing of the transpeptidase regions of pbp1a, -1b, and -2 was performed. While numerous changes were observed compared to the sequences from Rd, no consistent pattern correlating with high-level ampicillin resistance was apparent. Additional analysis of the resistant BLNAR strains revealed frame shift insertions in acrR for all four high-level, ampicillin-resistant isolates. acrR was intact for all eight low-level ampicillin-resistant and four ampicillin-susceptible strains tested. A knockout of acrB made in one clinical isolate (initial mean ampicillin MIC of 10.3 micro g/ml) lowered the ampicillin MIC to 3.67 micro g/ml, typical for BLNAR strains. These studies illustrate that BLNAR strains with high ampicillin MICs exist that have combined resistance mechanisms in PBP3 and in the AcrAB efflux pump.     

Genotypic versus phenotypic characterization, with respect to beta-lactam susceptibility, of Haemophilus influenzae isolates exhibiting decreased susceptibility to beta-lactam resistance markers

Among 165 Spanish Haemophilus influenzae isolates with mutations in the ftsI gene (ftsI⁺) (2005 to 2007), 73% were β-lactamase negative and 26.7% were positive. The proportion of β-lactamase-negative isolates to β-lactamase-positive isolates was 2:1 to 4:1 in general, versus 1:3 in pediatric hospitals. Among 44 β-lactamase-positive strains, 8 strains produced ROB-1 (5 from the pediatric hospital). β-Lactamase-positive ftsI⁺ strains were phylogenetically closer than were β-lactamase-negative strains.     

Ampicillin-resistant non-beta-lactamase-producing Haemophilus influenzae in Spain: recent emergence of clonal isolates with increased resistance to cefotaxime and cefixime

The sequence of the ftsI gene encoding the transpeptidase domain of penicillin-binding protein 3 (PBP 3) was determined for 354 nonconsecutive Haemophilus influenzae isolates from Spain; 17.8% of them were ampicillin susceptible, 56% were beta-lactamase nonproducing ampicillin resistant (BLNAR), 15.8% were beta-lactamase producers and ampicillin resistant, and 10.4% displayed both resistance mechanisms. The ftsI gene sequences had 28 different mutation patterns and amino acid substitutions at 23 positions. Some 93.2% of the BLNAR strains had amino acid substitutions at the Lys-Thr-Gly (KTG) motif, the two most common being Asn526 to Lys (83.9%) and Arg517 to His (9.3%). Amino acid substitutions at positions 377, 385, and 389, which conferred cefotaxime and cefixime MICs 10 to 60 times higher than those of susceptible strains, were found for the first time in Europe. In 72 isolates for which the repressor acrR gene of the AcrAB efflux pump was sequenced, numerous amino acid substitutions were found. Eight isolates with ampicillin MICs of 0.25 to 2 microg/ml showed changes that predicted the early termination of the acrR reading frame. Pulsed-field gel electrophoresis analysis demonstrated that most BLNAR strains were genetically diverse, although clonal dissemination was detected in a group of isolates presenting with increased resistance to cefotaxime and cefixime. Background antibiotic use at the community level revealed a marked trend toward increased amoxicillin-clavulanic acid consumption. BLNAR H. influenzae strains have arisen by vertical and horizontal spread and have evolved to adapt rapidly to the increased selective pressures posed by the use of oral penicillins and cephalosporins.     

Mechanism of resistance of an ampicillin-resistant, beta-lactamase-negative clinical isolate of Haemophilus influenzae type b to beta-lactam antibiotics

The mechanism of non-beta-lactamase-mediated beta-lactam resistance in a clinical isolate of Haemophilus influenzae type b was studied. This clinical isolate showed up to a 32-fold increase in MICs of a wide variety of beta-lactams, including moxalactam and cefotaxime, although no beta-lactamase activity was detected, even after attempted induction. Transformation of broad-spectrum beta-lactam resistance into ampicillin-susceptible H. influenzae RDnov was accomplished. Examination of the outer membrane protein profile of the resistant parent by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of Triton X-100-extracted membranes revealed an unusual major outer membrane protein band at a molecular weight of 45,000. This outer membrane protein profile did not transform with beta-lactam resistance. Permeability differences were noted between the resistant strain and the nonisogenic susceptible strain of H. influenzae, although these penetration differences were not transformed. Comparison of the penicillin-binding protein profile of a resistant transformant with that of a susceptible parent with both whole-membrane preparations and whole-cell labeling, revealed a major reduction in binding affinity to penicillin-binding proteins 3a and 3b (molecular weights, 68,000 and 65,000, respectively). Thus, alteration in penicillin-binding proteins 3a and 3b correlated with the beta-lactam resistance.     

Association of amino acid substitutions in penicillin-binding protein 3 with beta-lactam resistance in beta-lactamase-negative ampicillin-resistant Haemophilus influenzae

The affinity of [(3)H]benzylpenicillin for penicillin-binding protein (PBP) 3A was reduced in 25 clinical isolates of beta-lactamase-negative ampicillin (AMP)-resistant (BLNAR) Haemophilus influenzae for which the AMP MIC was > or =1.0 microg/ml. The affinities of PBP 3B and PBP 4 were also reduced in some strains. The sequences of the ftsI gene encoding the transpeptidase domain of PBP 3A and/or PBP 3B and of the dacB gene encoding PBP 4 were determined for these strains and compared to those of AMP-susceptible Rd strains. The BLNAR strains were classified into three groups on the basis of deduced amino acid substitutions in the ftsI gene, which is thought to be involved in septal peptidoglycan synthesis. His-517, near the conserved Lys-Thr-Gly (KTG) motif, was substituted for Arg-517 in group I strains (n = 9), and Lys-526 was substituted for Asn-526 in group II strains (n = 12). In group III strains (n = 4), three residues (Met-377, Ser-385, and Leu-389), positioned near the conserved Ser-Ser-Asn (SSN) motif, were replaced with Ile, Thr, and Phe, respectively, in addition to the replacement with Lys-526. The MICs of cephem antibiotics with relatively high affinities for PBP 3A and PBP 3B were higher than those of AMP and meropenem for group III strains. The MICs of beta-lactams for H. influenzae transformants into which the ftsI gene from BLNAR strains was introduced were as high as those for the donors, and PBP 3A and PBP 3B showed decreased affinities for beta-lactams. There was no clear relationship between 7-bp deletions in the dacB gene and AMP susceptibility. Even though mutations in another gene(s) may be involved in beta-lactam resistance, these data indicate that mutations in the ftsI gene are the most important for development of resistance to beta-lactams in BLNAR strains.     

First characterization of heterogeneous resistance to imipenem in invasive nontypeable Haemophilus influenzae isolates

This study describes the first two reported invasive nontypeable Haemophilus influenzae (NTHI) isolates (strains 183 and 184) with heterogeneous resistance to imipenem. For both isolates, Etest showed imipenem MICs of > or =32 microg/ml. When the two strains were examined by the quantitative method of population analysis, both strain populations were heterogeneously resistant to imipenem and contained subpopulations growing in the presence of up to 32 microg of imipenem/ml at frequencies of 1.7 x 10(-5) and 1.5 x 10(-7), respectively. By pulsed-field gel electrophoresis analysis, the two isolates appeared to be genetically closely related. The sequencing of the ftsI gene encoding penicillin-binding protein 3 (PBP 3) and comparison with the sequence of the imipenem-susceptible H. influenzae strain Rd identified a pattern of six amino acid substitutions shared between strains 183 and 184; an additional change was unique to strain 183. No relationship between mutations in the dacB gene encoding PBP 4 and imipenem resistance was found. The replacement of the ftsI gene in the imipenem-susceptible strain Rd (for which the MIC of imipenem is 0.38 to 1 microg/ml) with ftsI from strain 183 resulted in a transformant for which the MIC of imipenem ranged from 4 to 8 microg/ml as determined by Etest. The Rd/183 transformant population showed heterogeneous resistance to imipenem; it contained subpopulations growing in the presence of up to 32 mug of imipenem/ml at a frequency of 3.3 x10(-8). The presence of additional resistance mechanisms, such as the overexpression of the AcrAB efflux pump, was investigated and does not seem to be involved. These data indicate that the heterogeneous imipenem resistance phenotype of our NTHI clone depends largely on the PBP 3 amino acid substitutions. We speculated that bacterial regulatory networks may play a role in the control of the heterogeneous expression of the resistance phenotype.     

Antimicrobial resistance in Haemophilus influenzae and Moraxella catarrhalis respiratory tract isolates: results of the Canadian Respiratory Organism Susceptibility Study, 1997 to 2002

A total of 7,566 unique patient isolates of Haemophilus influenzae and 2,314 unique patient isolates of Moraxella catarrhalis were collected between October 1997 and June 2002 from 25 medical centers in 9 of the 10 Canadian provinces. Among the 7,566 H. influenzae isolates, 22.5% produced beta-lactamase, while 92.4% of the 2,314 M. catarrhalis isolates produced beta-lactamase. The incidence of beta-lactamase-producing H. influenzae isolates decreased significantly over the 5-year study period, from 24.2% in 1997-1998 to 18.6% in 2001-2002 (P < 0.01). The incidence of beta-lactamase-producing M. catarrhalis isolates did not change over the study period. The overall rates of resistance to amoxicillin and amoxicillin-clavulanate for H. influenzae were 19.3 and 0.1%, respectively. The rank order of cephalosporin activity based on the MICs at which 90% of isolates were inhibited (MIC(90)s) was cefotaxime > cefixime > cefuroxime > cefprozil > cefaclor. On the basis of the MICs, azithromycin was more active than clarithromycin (14-OH clarithromycin was not tested); however, on the basis of the NCCLS breakpoints, resistance rates were 2.1 and 1.6%, respectively. Rates of resistance to other agents were as follows: doxycycline, 1.5%; trimethoprim-sulfamethoxazole, 14.2%; and chloramphenicol, 0.2%. All fluoroquinolones tested, including the investigational fluoroquinolones BMS284756 (garenoxacin) and ABT-492, displayed potent activities against H. influenzae, with MIC(90)s of < or = 0.03 microg/ml. The MIC(90)s of the investigational ketolides telithromycin and ABT-773 were 2 and 4 microg/ml, respectively, and the MIC(90) of the investigational glycylcycline GAR-936 (tigecycline) was 4 microg/ml. Among the M. catarrhalis isolates tested, the resistance rates derived by using the NCCLS breakpoint criteria for H. influenzae were <1% for all antibiotics tested except trimethoprim-sulfamethoxazole (1.5%). In summary, the incidence of beta-lactamase-positive H. influenzae strains in Canada is decreasing (18.6% in 2001-2002), while the incidence of beta-lactamase-positive M. catarrhalis strains has remained constant (90.0% in 2001-2002).     

High levels of multiple antibiotic resistance among 938 Haemophilus influenzae type b meningitis isolates from Cuba (1990-2002)

OBJECTIVES: A national surveillance study to determine antimicrobial susceptibility in Haemophilus influenzae type b isolated from cerebrospinal fluid was carried out in Cuba from 1990 to 2002. METHODS: Susceptibility to ampicillin, co-amoxiclav, cefotaxime, ceftriaxone, co-trimoxazole, tetracycline, chloramphenicol and rifampicin was tested by the microdilution method according to the NCCLS guidelines. RESULTS: The 34 participating laboratories recovered 938 consecutive, non-identical isolates. All the isolates were retrieved from children aged <5 years. The mean number of isolates collected by year in the pre-vaccination era (1990-1998) was 93; after vaccination, 57 isolates were reported in 1999, 31 in 2000, four in 2001 and five in 2002. Resistance to ampicillin, co-trimoxazole, tetracycline and chloramphenicol was 46.3% (all beta-lactamase-positive), 51.3%, 33.2% and 44.0%, respectively. Ampicillin-resistant beta-lactamase-negative strains were not detected. All strains were susceptible to co-amoxiclav, cefotaxime, ceftriaxone and rifampicin. Ampicillin resistance was strongly associated with resistance to tetracycline, co-trimoxazole and chloramphenicol (P<0.001). Multidrug resistance was present in 43.8% of isolates. The most prevalent phenotype was resistance to ampicillin/chloramphenicol/tetracycline/co-trimoxazole, which was detected in 29.2% of strains overall. An increase in the prevalence of resistance to these antibiotics was observed from 1990 to 2000 in the range 40.7%-54.8% for ampicillin, 40.1%-51.6% for chloramphenicol, 45.4%-58.1% for co-trimoxazole and 23%-45.2% for tetracycline. CONCLUSIONS: In Cuba, the widespread vaccination against Haemophilus influenzae type b prevented a large number of meningitis cases in children caused by strains resistant to multiple antibiotics.     

137例儿童急性下呼吸道感染流感嗜血杆菌耐药性分析

目的了解我院2004年1月至2006年8月急性细菌性下呼吸道感染（ALRTI）患儿痰中分离的137株流感嗜血杆菌（Hi）耐药性及产酶率。方法用ATB药敏鉴定条对痰液中分离的137株Hi做药敏试验及B内酰胺酶测定。结果小于3岁组儿童Hi117株，占85．4％；对氨苄西林耐药43株，耐药率为31．4％；产D内酰胺酶25株，产酶率18．2％；耐药主要集中在氨苄西林、红霉素、利福平、复方磺胺甲咏唑和苯唑西林，且多重耐药91株，占66．4％。结论Hi是引起儿童ALRTI的常见病原菌，多见3岁以下儿童，对红霉素、复方磺胺甲嘿唑、利福平和氨苄西林的耐药率较高，本研究结果为合理选用抗菌药物提供依据。     

Antibiotic resistance in Campylobacter strains isolated from animals, foods, and humans in Spain in 1997-1998

Colonization by Campylobacter strains was investigated in human, broiler, and pig fecal samples from 1997-1998, as well as in foods of animal origin, and antibiotic susceptibility testing was carried out for these strains. Campylobacter strains were isolated in the foods of animal origin (55 of 101 samples; 54.4%), intestinal samples from broilers (85 of 105; 81%), and pigs (40 of 45; 88.9%). A total of 641 Campylobacter strains were isolated from 8,636 human fecal samples of clinical origin (7.4%). Campylobacter jejuni was the most frequently isolated species from broilers (81%) and humans (84%), and Campylobacter coli was most frequently isolated from pigs (100%). An extremely high frequency of ciprofloxacin resistance was detected among Campylobacter strains, particularly those isolated from broilers and pigs (99%), with a slightly lower result for humans (72%); cross-resistance with nalidixic acid was almost always observed. A higher frequency of resistance to erythromycin (81.1%), ampicillin (65.7%), gentamicin (22.2%), and amikacin (21.6%) was detected in C. coli strains isolated from pigs compared to those isolated from humans (34.5, 29.3, 8.6, and 0%, respectively). A low frequency of erythromycin resistance was found in C. jejuni or C. coli isolated from broilers. A greater resistance to ampicillin and gentamicin (47.4 and 11.9%, respectively) was detected in C. jejuni isolated from broilers than in human strains (38 and 0.4%, respectively). Beta-lactamase production was found in 81% of the Campylobacter strains tested, although 44% of them were characterized as ampicillin susceptible. The increasing rates of Campylobacter resistance make advisable a more conservative policy for the use of antibiotics in farm animals.     

青岛地区部分医院临床分离嗜血杆菌的耐药性分析

目的了解山东省青岛地区部分医院临床分离流感嗜血杆菌和副流感嗜血杆菌的耐药性,为临床合理用药提供依据。方法用手工法和MICSCAN4半自动细菌鉴定分析仪,HNID鉴定板对分离培养的182株嗜血杆菌进行菌种鉴定。用纸片琼脂扩散（K—B）法进行药敏试验,采用头孢硝噻吩纸片法进行β内酰胺酶检测。结果临床分离流感嗜血杆菌74株和副流感嗜血杆菌108株,口内酰胺酶株产酶率分别为44．6％和50．9％。流感嗜血杆菌和副流感嗜血杆菌对氨苄西林敏感率分别为55．4％和49．1％,对甲氧苄啶-磺胺甲唾唑的敏感率分别为50．7％和28．8％。而对头孢噻肟、头孢呋辛、阿奇霉素、左氧氟沙星和氯霉素的敏感率均高于80％。结论青岛地区呼吸道嗜血杆菌感染中以副流感嗜血杆菌为主,且产酶率较高,对嗜血杆菌属引起的呼吸道感染可选用头孢噻肟、头孢呋辛作为首选药物。对氨苄西林和甲氧苄啶-磺胺甲嚼唑的耐药率较高,已不宜用于嗜血杆菌感染的经验治疗。     

A survey of antibiotic resistance in Streptococcus pneumoniae and Haemophilus influenzae in Turkey, 2004 2005

OBJECTIVES: To determine the prevalence of antimicrobial resistance among Streptococcus pneumoniae and Haemophilus influenzae isolated in Turkey as part of Survey Of Antibiotic Resistance, a surveillance programme in the Africa and Middle East region examining the antimicrobial susceptibility of key bacterial pathogens involved in community-acquired respiratory tract infections (CARTIs). METHODS: Susceptibility was evaluated against a range of antimicrobial agents using disc diffusion and Etest methods. RESULTS: Six centres in five cities collected 301 S. pneumoniae and 379 H. influenzae isolates between October 2004 and November 2005. Among S. pneumoniae, the prevalence of isolates with intermediate susceptibility (MICs 0.12-1 mg/L) and resistance to penicillin (MICs >or=2 mg/L) was 24.6% and 7.6%, respectively; there was a wide variation between cities (2.4% to 36.9% intermediate and 0% to 23.8% resistant phenotypes). Macrolide-azalide resistance rates exceeded those of penicillin resistance in all cities. Overall, 5.0% of isolates were co-resistant to penicillin and erythromycin and 10.0% were multidrug-resistant (joint resistance to erythromycin, co-trimoxazole and tetracycline). Agents tested to which over 90% of countrywide S. pneumoniae isolates remained susceptible were amoxicillin/clavulanate (98.7%), chloramphenicol (94.7%) and cefprozil (90.6%). Overall, the percentage of H. influenzae isolates producing beta-lactamase was 5.5%, differing widely across the country with the highest prevalence of beta-lactamase production detected in Trabzon (14.0%) and no beta-lactamase-positive isolates found in Izmir. H. influenzae had the highest per cent susceptibility to amoxicillin/clavulanate (99.5%) and ofloxacin (99.2%) while >20% were resistant to co-trimoxazole. CONCLUSIONS: Prevalence of penicillin and macrolide-azalide resistance among S. pneumoniae appears to be on the increase in Turkey while overall beta-lactamase production in H. influenzae remains relatively low. To adequately monitor the spread of drug-resistant phenotypes among these two important CARTI pathogens, ongoing collection of resistance surveillance data is required-where possible locally as resistance patterns can vary substantially between cities and institutions.     

Genetic characteristics and antibiotic resistance of Haemophilus influenzae isolates from pediatric patients with acute otitis media after introduction of 13-valent pneumococcal conjugate vaccine in Japan

Acute otitis media (AOM) occurs commonly in pediatric populations. We examined resistance genotype, antibiotic susceptibility, quinolone (QL) resistance, and multilocus sequence type (MLST) among Haemophilus influenzae isolates causing AOM following introduction of pneumococcal conjugate vaccines in Japan.The AOM surveillance group included 69 participating otolaryngologists. Causative pathogens isolated from middle ear fluid (MEF) samples collected from 582 children with AOM were identified using both bacterial culture and real-time PCR. H. influenzae isolates among these pathogens were characterized by capsular type, resistance genotype, antibiotic susceptibility, QL resistance, and MLST.In 2016, H. influenzae was identified in 319 samples (54.8%), among which 72.4% (n = 231) tested positive by both culture and PCR; remaining H. influenzae cases were only PCR-positive. This proportion of H. influenzae positivity has increased significantly from 41.2% in 2006 (p < 0.001). Among culture-positive strains, genotypic β-lactamase-nonproducing ampicillin (AMP)-resistant (gBLNAR) strains were frequent (63.2%), with β-lactamase-nonproducing AMP-susceptible (gBLNAS) strains accounting for only 24.2%. Susceptibilities of gBLNAR to oral antimicrobials were best for tosufloxacin, followed by cefditoren and tebipenem; MIC₉₀s were 0.031 μg/mL, 0.5 μg/mL, and 1 μg/mL, respectively. In 7 gBLNAR isolates (3.0%), QL susceptibility was low, owing to amino acid substitutions in GyrA and/or ParC. Sequence types identified numbered 107, including 28 that were new.Prevention of further increases in resistance to antimicrobial agents will require antibiotic selection based on characterization of causative pathogens in clinical practice.     

Activity of a new carbapenem antibiotic, meropenem, against Haemophilus influenzae strains with beta-lactamase- and non-enzyme-mediated resistance to ampicillin.

Meropenem was 8- to 32-fold more active (MIC for 90% of strains = 0.125 micrograms/ml) than imipenem against a collection of Haemophilus influenzae strains characterized as either susceptible to ampicillin or resistant to that agent by virtue of beta-lactamase or nonenzymatic mechanisms. MBCs and kinetic kill curve tests showed that meropenem (as well as imipenem, several cephalosporins, and amoxicillin-clavulanate) was bactericidal against all strains at or within four times the respective MICs. Thus, meropenem demonstrated greater inhibitory activity than imipenem and activity comparable to that of cefotaxime against these selected strains.     

2005-2007年儿科分离的流感嗜血杆菌、肺炎链球菌(包括血清型19A)和卡他莫拉菌对常用抗菌药物的敏感性

儿科上呼吸道感染最常见的3种病原菌为未分型流感嗜血杆菌、肺炎链球菌和卡他莫拉菌。其中,19A血清型肺炎链球菌越来越多,且对多种药物呈高水平耐药,包括青霉素、阿莫西林、口服头孢菌素、大环内酯类、克林霉素和磺胺甲嗯唑一甲氧苄啶等。另外,未分型流感嗜血杆菌产β内酰胺酶,也导致对阿莫西林和部分口服头孢菌素耐药。