Natural Antibiotic Susceptibility of Enterobacter spp., with Special Reference to Enterobacter aerogenes and Enterobacter intermedius Strains

Abstract

The natural susceptibility to 71 antibiotics of 44 strains of Enterobacter aerogenes and 12 strains of Enterobacter intermedius was examined using a microdilution procedure in Isosensitest broth (for all strains) and cation-adjusted Mueller Hinton broth (for some strains). Both species were naturally sensitive or sensitive and intermediate to tetracyclines, all tested aminoglycosides, several penicillins and cephalosporins, carbapenems, aztreonam, quinolones, folate-pathway inhibitors, chloramphenicol and nitrofurantoin. Uniform natural resistance was found to cefoxitin and to antibiotics to which most other Enterobacteriaceae are also intrinsically resistant, e.g. several macrolides, lincosamides, streptogramins and glycopeptides. Major species-specific differences in susceptibility affecting clinical assessment criteria were found with amoxycillin, amoxycillin-clavulanate, some narrow-spectrum cephalosporins and fosfomycin. With the exception of penicillin G, oxacillin and cefoxitin, E. intermedius was naturally sensitive or naturally sensitive and intermediate (azlocillin) to all β-lactams tested.

Natural antibiotic susceptibility patterns of E. aerogenes and E. intermedius were analyzed with regard to the underlying mechanisms. The data were compared with the results from two recent studies dealing with natural susceptibilities of other clinically-relevant Enterobacter spp. With reference to β-lactam susceptibility patterns, it can be assumed that all human-affecting Enterobacter species examined produce species-specific, chromosomallyencoded β-lactamases of the AmpC type. The naturally-expressed amount of enzyme depends on the species.     

Natural antibiotic susceptibility of Ewingella americana strains

The natural susceptibility of 20 Ewingella americana strains to 72 antibiotics was examined. MIC values were determined using a microdilution procedure in cation-adjusted Mueller-Hinton broth. Evaluation of natural antibiotic susceptibility was performed applying the German standard (where applicable). Beta-lactamases were examined with a conventional nitrocefin colony testing procedure, activity and induction assays, and SDS-PAGE. Ewingella strains were naturally resistant or of intermediate susceptibility to cefaclor, loracarbef, cefazoline, cefuroxime, cefoxitin, benzylpenicillin, oxacillin, fosfomycin, erythromycin, roxithromycin, clarithromycin, lincosamides, dalfopristin-quinupristin, ketolides, linezolid, glycopeptides, fusidic acid and rifampicin. Uniform natural sensitivity was found with acylureidopenicillins except for azlocillin, ticarcillin, several cephalosporins, carbapenems, aztreonam, tetracyclines, aminoglycosides, quinolones, azithromycin, folate-pathway inhibitors and chloramphenicol. Strains of E. americana were naturally sensitive or of intermediate susceptibility to aminopenicillins (with and without beta-lactamase inhibitors), azlocillin and nitrofurantoin. All ewingellae yielded beta-lactamases; testing of representative strains revealed that these enzymes belong to Ambler class C. Inducibility of beta-lactamase was shown for E. americana ATCC 33852T, CCUG 35675 and CCUG 42782. The present study describes a database concerning the natural susceptibility of E. americana strains to a range of antibiotics, which can be applied to validate forthcoming antibiotic susceptibility tests of these bacteria. It enlarges the number of Enterobacteriaceae expressing naturally-occurring AmpC beta-lactamases.     

Natural antibiotic susceptibility of Enterobacter spp., with special reference to Enterobacter aerogenes and Enterobacter intermedius strains

The natural susceptibility to 71 antibiotics of 44 strains of Enterobacter aerogenes and 12 strains of Enterobacter intermedius was examined using a microdilution procedure in Isosensitest broth (for all strains) and cation-adjusted Mueller Hinton broth (for some strains). Both species were naturally sensitive or sensitive and intermediate to tetracyclines, all tested aminoglycosides, several penicillins and cephalosporins, carbapenems, aztreonam, quinolones, folate-pathway inhibitors, chloramphenicol and nitrofurantoin. Uniform natural resistance was found to cefoxitin and to antibiotics to which most other Enterobacteriaceae are also intrinsically resistant, e.g. several macrolides, lincosamides, streptogramins and glycopeptides. Major species-specific differences in susceptibility affecting clinical assessment criteria were found with amoxycillin, amoxycillin-clavulanate, some narrow-spectrum cephalosporins and fosfomycin. With the exception of penicillin G, oxacillin and cefoxitin, E. intermedius was naturally sensitive or naturally sensitive and intermediate (azlocillin) to all beta-lactams tested. Natural antibiotic susceptibility patterns of E. aerogenes and E. intermedius were analyzed with regard to the underlying mechanisms. The data were compared with the results from two recent studies dealing with natural susceptibilities of other clinically-relevant Enterobacter spp. With reference to beta-lactam susceptibility patterns, it can be assumed that all human-affecting Enterobacter species examined produce species-specific, chromosomally-encoded beta-lactamases of the AmpC type. The naturally-expressed amount of enzyme depends on the species.     

Extended-Spectrum β-Lactamases Conferring Resistance to Monobactams and Oxyimino-Cephalosporins in Clinical Isolates of Serratia marcescens

Abstract

We studied antibiotic resistance patterns and extended-spectrum β-lactamases (ESβLs) production in Serratia marcescens strains isolated in our hospital during 1993. We examined 210 S. marcescens isolates. Of these, 172 were obtained from 49 patients admitted to an intensive care ward; 157 out of 172 were obtained from February to October and presented the same pattern of antibiotic resistance, including monobactams and oxyimino-cephalosporins. The remaining 15 out of 172 isolates (obtained from September to December) were susceptible to all drugs tested, with the exception of first generation cephalosporins. Thirty-eight additional isolates were recovered, during the same period, from 28 patients admitted to wards other than the intensive care unit; also these strains showed the high susceptibility pattern reported above.

Epidemic strains of S. marcescens produced three different types of β-lactamase with pI 5.4, 5.5, and 8.4. In contrast, non-epidemic strains produced only one type of β-lactamase with pI 8.4. Conjugation experiments showed that the β-lactamases having a pI of 5.4 and 5.5 (but not the one with pI 8.4) were plasmid-mediated. Since the β-lactamase with pI 5.5 was capable of hydrolyzing monobactams and oxyimino-cephalosporins it was classified as ESβL. Electrophoretic analysis showed that plasmids obtained from multiresistant strains were of about 54 kb; these plasmids appeared also to code for aminoglycoside resistance. Our data indicate that the plasmid-mediated production of ESβLs may contribute to the epidemic spread of Serratia marcescens in high-risk wards.     

A Synthetic γ-Lactone Group with β-Lactamase Inhibitory and Sporulation Initiation Effects

Abstract

Previous studies showed that some lactones have β-lactamase inhibitory or antibacterial effects, others—like A-factor (a γ-butyrolactone) and its derivatives—stimulate sporulation in Streptomyces griseus strains. Our experiments were aimed at exploring whether synthetic γ-lactones had such effects. None of the seven γ-lactones studied showed antibacterial activity, but two of them inhibited β-lactamases isolated from various bacteria. These two γ-lactones did not reduce colony formation of murine bone marrow cells in vitro, indicating that they were not toxic to proliferating mammalian cells. Four γ-lactones, including the two inhibiting β-lactamase, stimulated sporulation in the non-sporulating S. griseus bald 7 mutant. Further studies of γ-lactones as potential inhibitors of β-lactamase seem to be warranted.     

Antimicrobial Resistance and Prevalence of Extended Spectrum β-Lactamase Among Clinical Isolates of Gram-Negative Bacteria in Riyadh

Abstract

The activity of ciprofloxacin, imipenem and 12 other commonly used antibiotics was evaluated against 106 documented clinical isolates from a medical Intensive Care Unit (ICU). The resistance rates to ceftriaxone, cefotaxime, aztreonam and ceftazidime were 42, 25, 24 and 21%, respectively. Apart from Pseudomonas aeruginosa, all isolates were sensitive to ciprofloxacin and imipenem. Complete cross resistance among tested β-lactam groups was uniformly evident in Enterobacter cloacae, Citrobacter freundii and P. aeruginosa. On the other hand, penicillins and second generation cephalosporins showed cross resistance among Escherichia coli and Klebseilla pneumoniae isolates. Induction experiments indicate that 70 and 62% of P. aeruginosa and E. cloacae or C. freundii produce class I cephalosporinase, respectively.

Among all tested isolates, plasmid mediated extended spectrum β-lactamase (ESBL) was detected in one isolate of K. pneumoniae. The plasmid mediated β-lactamase is transferable and inhibited by β-lactamase inhibitors. The transconjugates not only expressed resistance to extended spectrum β-lactams and aztreon-am but also toward tested aminoglycoside antibiotics, with the exception of gentamicin. The obtained transconjugates conferred high level resistance to cef-tazidime and aztreonam but considerably low resistance to ceftriaxone and cefotaxime. The isoelectric point for the extended-spectrum β-lactamase is 8.2.     

Neoadjuvant Chemotherapy with Cisplatinum and 5-Fluorouracil in Advanced Head and Neck Cancer

Summary

Boric and boronic acids were used as inhibitors of β-lactamases produced by two Citrobacter diversus strains and by one strain of Pseudomonas aeruginosa; all strains were clinical isolates. The β-lactamases produced by the two Citrobacter diversus strains were inhibited by both borates and boronates, using cephazolin as substrate.

The enzyme from Pseudomonas aeruginosa was inhibited only by boronates, using benzylpenicillin as substrate.

These inhibitors were also used in combination with selected β-lactams so as to determine if a synergism of antimicrobial activity occurred.

All data reported in the present paper indicate that the minimum inhibitory concentration (MIC) values were lowered in the presence of these inhibitors for the two Citrobacter diversus strains. In the Pseudomonas aeruginosa strains the MIC values were not significantly altered, thus indicating the presence of a permeability barrier for 3-aminophenylboronic acid.     

High Prevalence of Extended Spectrum Beta-Lactamase Production Among Klebsiella pneumoniae Strains Isolated at a University Hospital in Turkey

Abstract

β-lactam susceptibility and β-lactamase patterns of a random sample of 44 Klebsiella pneumoniae strains that had been isolated from nosocomial infections at Dokuz Eyliil University Hospital in Izmir, were investigated. All strains were amoxycillin resistant but in the presence of clavulanic acid 26 became sensitive. Similarly 39 of the strains were resistant to ceftazidime and cefo-taxime; clavulanic acid restored sensitivity to ceftazidime in 28 and to cefo-taxime in 25 of these resistant strains. Extended spectrum β-lactamase (ESBL) production was positive in 84% of the isolates as determined by the double disk synergy test. Isoelectric focusing revealed that each strain produced one to four β-lactamases, pI 7.6 enzymes being the most prevalent. Other enzymes with pIs of 8.4, 8.2, 5.4, 7.8 were also detected. Resistance to ceftazidime was transferred from 18 of the 44 isolates to the recipient Escherichia coli K-12 at 37°C. The transconjugants were examined for their plasmid content and the plasmids were characterized by their size and resistance profile. Fourteen different restriction pattern groups were identified with Eco R1. The results indicate a high prevalence of ESBL production in nosocomial K. pneumoniae isolates in Izmir and have major implications concerning the clinical use of later generation cephalosporins.     

Cefaclor: A Contemporary Look at Susceptibility of Key Pathogens from Around the Globe

Abstract

The orally administered cephalosporin antibiotic, cefaclor, has been available for clinical use in many countries since 1979. Because widespread antibiotic use is often cited as a factor in the emergence of bacterial resistance to antibiotics, we sought to determine the degrees of resistance to cefaclor expressed by key pathogens recently isolated in 10 countries widely distributed around the world. Using the E-test ®, minimal inhibitory concentrations (MIC) were determined for cefaclor and several comparator antibiotics against approximately 700 fresh clinical isolates of each of six bacterial species. The results demonstrated that > 90% of Haemophilus influenzae (β-lactamase producing and non-producing), Haemophilus parainfluenzae (β-lactamase producing and non-producing), Moraxella catarrhalis (> 90% β-lactamase producing), and methicillin-susceptible Staphylococcus aureus, and 85% of Escherichia coli were susceptible to cefaclor at the NCCLS interpretive breakpoints. MIC distributions showed that there has been no change in the activity of cefaclor against penicillin-susceptible strains of Streptococcus pneumoniae since 1977.     

Natural antibiotic susceptibility of Proteus spp., with special reference to P. mirabilis and P. penneri strains

The natural susceptibility of 102 Proteus mirabilis and 35 Proteus penneri strains to 71 antibiotics was examined. Minimum inhibitory concentrations (MICs) were determined by applying a microdilution procedure in IsoSensitest broth (for all strains) and cation-adjusted Mueller Hinton broth (for some strains). P. mirabilis and P. penneri were naturally resistant to penicillin G, oxacillin, all tested macrolides, lincosamides, streptogramins, glycopeptides, rifampicin and fusidic acid. Both species were uniformly, naturally sensitive to all tested aminoglycosides, acylureidopenicillins, some cephalosporins, carbapenems, aztreonam, quinolones, sulfamethoxazole and co-trimoxazole. Species-specific differences in natural susceptibility affecting clinical assessment criteria were seen with tetracyclines, several beta-lactams, chloramphenicol and nitrufurantoin. P. mirabilis was naturally resistant to all tested tetracyclines, and was naturally sensitive to all beta-lactams, except penicillin G and oxacillin. Strains of P. penneri were naturally sensitive or of intermediate susceptibility to tetracyclines, and naturally resistant to amoxicillin (but sensitive or of intermediate susceptibility to aminopenicillins in the presence of beta-lactamase inhibitors) and some cephalosporins (i.e. cefaclor, cefazoline, loracarbef, cefuroxime, cefotiam, and cefdinir). P. penneri was less susceptible than P. mirabilis to chloramphenicol; P. mirabilis was less susceptible than P. penneri to nitrofurantoin. Major medium-dependent influences on the MICs were seen with fosfomycin. The present study describes a database concerning the natural antibiotic susceptibility of P. mirabilis and P. penneri strains to a range of antibiotics, which can be applied to validate forthcoming antibiotic susceptibility tests of these bacteria. It was shown that ten of fifteen amoxicillin-sensitive P. mirabilis strains produced beta-lactamases at a low level, supporting the thesis of the presence of a naturally-occurring beta-lactamase in this species. Natural susceptibility patterns are compared with those of a recent study, dealing with natural susceptibilities of species of the P. vulgaris complex.     

First Report of a Novel Extended-Spectrum Beta-Lactamase KOXY-2 Producing Klebsiella oxytoca that Hydrolyses Cefotaxime and Ceftazidime

Abstract

Klebsiella oxytoca strains MU946294N and MB193997E were isolated from patients in Scotland. Strain MU946294N was resistant to pencillins, monbactams and cephalosporins. Isolate MB193997E displayed a β-lactam resistance phenotype consistent with chromosomal β-lactamase overproduction. No bla _TEM, bla _SHV or bla _CTX-M genes could be amplified in either strain; however, amplification by PCR was found with primers for the bla _OXY-2 gene. This β-lactamase gene in MU946294N differed by one mutation from the all other bla _OXY genes previously reported, with an amino acid substitution Alanine237 Threonine enhancing the binding of cefotaxime. Strain MB193997E showed mutations at positions 255 and 283, neither of which affect function. Based on rpoB and gyrA characterization, both strains were assigned to the KoII phylogenic group but they were completely dissimilar from each other by PFGE. This study is the first to report the substitution of Alanine to Threonine at position 237 in a OXY-2 β-lactamase and this enhances resistance to cefotaxime.     

Effect of Temperature on Antimicrobial Susceptibilities of Pseudomonas Species Isolated from Drinking Water

Summary

The susceptibility of 20 strains of Pseudomonas species isolated from drinking waters (4 P. aeruginosa, 7 P. fluorescens, 5 P. stutzeri, 1 P. maltophilia, 1 P. cepacia, 1 P. putida and 1 P. pickettii) to a variety of antibiotics (gentamicin, amikacin, azlocillin, cefotaxime, chloramphenicol and polymyxin B) were determined by Stoke’s method at 20°C, 30°C, 37°C and 42°C.

Minimum inhibitory concentrations (MIC) were determined for aminoglycosides on Mueller-Hinton agar at the above temperatures. There was a significant difference in susceptibility between 20°C or 30°C (most resistant), 37°C (more susceptible) and 42°C (most susceptible) to gentamicin and to a lesser degree to amikacin for P. maltophilia, P. cepacia and most strains of P. fluorescens. The P. aeruginosa, P. stutzeri, P. putida and P. pickettii strains showed no difference in susceptibility at 20°C, 30°C, 37°C and 42°C. The need for standardized conditions with special regard to temperature when antibiotic susceptibility tests are performed for P. maitophilia, P. cepacia and P. fluorescens strains is stressed.     

Heavy Metals,Chlorine and Antibiotic Resistance in Escherichia coli Isolates from Ambulatory Patients

Summary

The susceptibility of Escherichia coli strains isolated from ambulatory patients to heavy metals, chlorine and antibiotics was evaluated. It seemed that heavy metal resistance was associated with antibiotic resistance. On the other hand, chlorine resistant strains seemed to be more sensitive to antibiotics. Clinical and ecological implications of these results are discussed.     

Susceptibility of Respiratory and Urinary Pathogens to Ceftibuten and Other Comparative Drugs: Results of an Italian Multicenter Survey

Summary

A survey aimed at assessing the ability of ceftibuten, a new oral third-generation cephalosporin, to eradicate in Vitro selected bacterial pathogens was conducted in 1991 in 17 microbiology laboratories evenly distributed in Italy. Over 8700 organisms collected from in- and outpatients affected mainly by respiratory and urinary tract infections were analyzed. This collection of bacteria did not include staphylococci, enterococci, Pseudomonta and other oxidative species naturally refractory to the action of most antibiotics employed.

Susceptibility to ceftibuten, cefaclor, cefuroxime, amoxicillin, amoxicillin-clavulanate, cotrimoxazole and erythromycin was assessed using a standardized agar-diffusion method. Production of β-lactamases was confirmed by the nitrocefin test. Among the microorganisms studied E. coli (32.1%) prevailed, followed by P. mirabilis (17.1%), K. pneumoniae (10.9%), 5. pyogenes (6.6%), E. cloacae (5.1%), Serratia spp. (4.5%), Enterobacter spp. (4.2%), H. influenzae (3.6%), S. pneumoniae (2.2%) and Af. catarrhalis (2%). Within this group of pathogens amoxicillin resistance, often mediated by synthesis of P-lactamases, was widely diffused (46.2%). The overall inhibitory activity of the drugs tested decreased as follows: ceftibuten (90.4%), cefuroxime (80.4%), amoxicillin-clavulanate (77.4%), cotrimoxazole (75.3%), cefaclor (72.6%), amoxicillin (53.8%) and erythromycin (32.8%). When the efficacy of the antibiotics was assessed against the collection of respiratory isolates producing β-lactamases only ceftibuten maintained the same overall potency manifested against the general population while the comparative agents were far less effective. The results of this national survey indicate that, given the low incidence of resistance among the most prevalent causative agents of respiratory and urinary tract infections, ceftibuten can be safely used at present in the empiric therapy of these conditions especially when they occur in community settings.     

Natural antibiotic susceptibility of Rahnella aquatilis and R. aquatilis-related strains

A database is described of the natural susceptibilities of 70 Rahnella strains to 71 antibiotics. MIC values were determined by a microdilution procedure and evaluated by a table calculation program. Rahnella aquatilis and R. aquatilis-related strains were naturally resistant to amoxycillin, ticarcillin, fosfomycin and to antibiotics to which other species of Enterobacteriaceae are also intrinsically resistant, i.e. macrolides (except azithromycin), benzylpenicillin, oxacillin, rifampicin, fusidic acid, lincosamides and glycopeptides. Rahnella strains were also naturally resistant or intermediate to cefazolin, cefuroxime and loracarbef. All rahnellae were naturally sensitive or intermediate to doxycycline, minocycline, aminoglycosides, some penicillins and cephalosporins, carbapenems, aztreonam, quinolones, sulfamethoxazole, trimethoprim, cotrimoxazole, chloramphenicol and nitrofurantoin. Bimodal or broad MIC distributions were seen for several antibiotics, e.g. quinolones and cephalosporins. With the exception of quinolones no differences in natural antibiotic susceptibility were seen between reference strains of Rahnella genomovar 1 (n=6) and 2 (n=7). Reference strains of genomovar 1 were pyrase-positive and more susceptible to quinolones than reference strains of genomovar 2, which were pyrase-negative. By discrimination of all rahnellae in the pyrase-positive and pyrase-negative strains the MIC distributions for quinolones became smaller and unimodal. Under the conditions described pyrase might be a parameter to differentiate strains of Rahnella genomovars 1 and 2.     

«Nonantibiotics» - Their Relevance in Research and Potential Place in Future Antimicrobial Chemotherapy

Summary

The susceptibilities of gentamicin- and carbenicillin-resis-tant clinical isolates of Pseudomonas aeruginosa to newer β-lactams, netilmicin and ciprofloxacin were studied by a broth microdilution technique. Imipenem, aztreonam and ceftazi-dime were active against most of the P. aeruginosa strains with minimum inhibitory concentration (MIC) for 90% of the isolates at clinically achievable levels. Piperacillin, azlocillin, cefotaxime, ceftriaxone, cefsulodin, cefoperazone and netilmicin showed poor activity against these organisms, ciprofloxacin exhibited poor activity, inhibiting only 30% of these strains.     

Some Molecular Properties of Citrobacter diversus Beta-Lactamases

Summary

Citrobacter diversus ULA-27, a clinical isolate showing a broad resistance pattern towards both penicillins and cephalosporins, produces chromosome encoded β-lactamases. However, the strain remains susceptible to some cephamycins, imipenem, ceftazidime and tetracyclines.

Crude bacterial extracts analyzed by isoelectric focusing on polyacrylamide gels, revealed the presence of two main isoforms and some «satellite» bands focusing in the pH range 5.7-7.2.

The isoform showing the pIs 6.8 and 6.2 were characterized as class «A» β-lactamases (according to Ambler's classification) based on the rate of interaction of β-iodopenicillanate and the aminoacid sequence around the active site serine. The substrate specificity of the Citrobacter diversus β-lactamases explains the resistance phenomenon of this bacterium to penicillins and cephalosporins.     

Kinetics of Antimicrobial Activity of Amoxicillin/Clavulanic Acid and Metronidazole against β-Lactamase-Producing Bacteroides fragilis Group

Summary

Bacteroides fragilis group are the most common anaerobic bacteria isolated in clinical specimens. The use of a beta-lactam with a β-lactamase inhibitor should result in a marked increase in the group's sensitivity to the β-lactams. Since the activity (MIC) shown by the amoxicillin + clavulanic acid combination against Bacteroides fragilis group is good, other parameters of in vitro activity have been studied. This study was also done with metronidazole. The minimum inhibitory concentration (MIC) was determined in 26 strains of Bacteroides fragilis group (14 B. fragilis; 5 B. thetaiotaomicron; 4 B. vulgatus; 3 B. distasonis). Likewise, the minimum bactericidal concentration (MBC), the killing curve, the sub-MIC and post-antibiotic effect were determined.

The MIC ranged between 0.5 and 32 mg/l. The MBC was two- to four-fold the MIC for amoxicillin/clavulanic acid, and one- to two-fold the MIC for metronidazole for most strains. The killing curve showed a continuous decrease, sloping most sharply between 0-2 hours and 6-8 hours. Amoxicillin + clavulanic acid showed a post-antibiotic effect between 2 and 4 hours. The inhibitory minimum antibiotic concentration was one-half the MIC for most strains.     

Comparison of the Efficiency of Three Methods for the Determination of Staphylococcal β-Lactamase

Summary

Three methods for demonstrating the production of β-lactamase in resistant strains of Staphylococcus aureus were compared. The «satellite phenomenon» method proved to he more sensitive than the nitrocefin test and the iodometric test.     

肿瘤患者呼吸道感染嗜血杆菌的临床分布与耐药性分析

  目的   分析肿瘤患者呼吸道感染嗜血杆菌的临床分布与耐药状况，为临床规范应用抗生素提供依据。   方法   收集2010年2月至2010年11月天津医科大学附属肿瘤医院住院的肿瘤患者早晨痰液样本，采用含有Ⅹ、Ⅴ因子的巧克力琼脂平板分离培养嗜血杆菌，应用Vitek2-Compact全自动细菌鉴定分析仪鉴定菌种，药敏试验采用微量肉汤稀释法进行。采用头孢硝噻吩纸片法检测β-内酰胺酶。   结果   从7 333份呼吸道标本中检出316株嗜血杆菌，其中流感嗜血杆菌95株，副流感嗜血杆菌221株。流感嗜血杆菌对头孢噻肟、左氧氟沙星、美罗培南均敏感，对复方新诺明、氨苄西林的耐药率分别为26.3%、15.8%。对头孢类及β-内酰胺/β-内酰胺酶抑制剂、大环内酯类、氯霉素类抗生素较敏感。副流感嗜血杆菌与流感嗜血杆菌的药敏谱相似。   结论   大多数抗菌药物对肿瘤患者呼吸道感染的嗜血杆菌仍保持良好的抗菌活性，临床应根据药敏结果规范使用抗菌药物。