Population genetics and antibiotic susceptibility of invasive Haemophilus influenzae in Manitoba, Canada, from 2000 to 2006

One hundred and twenty-two isolates of Haemophilus influenzae causing invasive disease were collected in Manitoba, Canada, from 2000 to 2006 and examined for serotype, biotype, sequence type (ST) by multilocus sequence typing and antibiotic susceptibility. Nonserotypeable (NST) isolates accounted for over half of the isolates collected (69 isolates, 56.6%). There were 36 serotype a, five serotype b, two serotype c, one serotype d, four serotype e and five serotype f isolates collected. The 69 NST isolates were found to be very diverse, with isolates representing six biotypes and 45 STs. The serotypeable isolates were more clonal, with each of the serotypes showing little diversity in their biotypes and STs. Of the 122 isolates, 17% were resistant to ampicillin due to beta-lactamase production, 10.7% were resistant to trimethoprim-sulfamethoxazole, 1.6% were resistant to clarithromycin, 2.5% were resistant to amoxicillin-clavulanic acid and none was resistant to ciprofloxacin or moxifloxacin. Antibiotic resistance was more common in the NST strains, with 37.7% showing resistance to at least one antibiotic compared to 15% in the serotypeable strains. The results of this study suggest a shift in the epidemiology of invasive H. influenzae infections in the post-Hib vaccine era, and surveillance should include all serotypeable and NST isolates.     

Comparative characteristics of the Haemophilus influenzae strains isolated from healthy children and from patients with acute and chronic bronchopulmonary diseases

The comparative biochemical and serological characterization of 424 H. influenzae strains isolated from healthy children and patients with acute and chronic bronchopulmonary diseases is presented. As the result of biotyping H. influenzae strains, 82.3-90.9% of the strains isolated from both healthy children and patients with acute and chronic bronchopulmonary diseases were found to belong to the first three biotypes according to M. Kilian's classification. Among H. influenzae strains isolated from healthy children no capsular variants were detected in the coagglutination test. From patients with acute and chronic diseases of respiratory organs, as a rule, the capsular variants of H. influenzae were isolated (94.4% and 98.1%, respectively). In patients with chronic pneumonia biotypes I, II and III, more seldom biotype V, proved to be mo st invasive. In the determination of the minimum inhibiting concentration of ampicillin, no H. influenzae strains resistant to this antibiotic were detected.     

Antibiotic resistance in Streptococcus pneumoniae and Haemophilus influenzae. Report of a study group on bacterial resistance.

Twenty laboratories in England and Scotland took part in 1977 in a survey of antibiotic resistance in Streptococcus pneumoniae and Haemophilus influenzae. In Str pneumoniae 59 (6.8%) of the 866 strains studied were resistant to tetracycline and three to chloramphenicol, and one strain showed a decreased susceptibility to penicillin. The prevalence of resistance to tetracycline was lower than that found in a similar study performed in 1975. Nine hundred and fifty-two strains of H influenzae were examined: 15 (1.6%) were resistant to ampicillin (all were beta-lactamase producers) and 26 (2.7%) to tetracycline. Only two strains were resistant to chloramphenicol and two to trimethoprim. Sixty-three H influenzae strains were capsulated. Thirty-four of these were of Pittman type b, and antibiotic resistance, particularly to ampicillin, was more common in these than in other serotypes or non-typable strains. Some variation was seen in the resistance rate of both H influenzae and Str pneumoniae to tetracycline in strains from different centres, but too few were isolated to assess whether this represented a true geographical difference.     

Ampicillin-Resistant Hemophilus influenzae: Emergence in California's Central Valley

Ampicillin-resistant Hemophilus influenzae had not been identified in Fresno, California, before June 1976. In the 12 months that followed, eight resistant type B strains and three resistant nontypable isolates were cultured from patients treated at two hospitals that provide nearly all of the acute pediatric inpatient care for the area. Two of the resistant strains were obtained from patients with invasive infections and represented 4.2 percent of Hemophilus influenzae isolated from blood, cerebrospinal fluid or joint aspirates during the 12 months. The remaining six resistant type B strains were obtained from 117 patients, and were the predominant organism in cultures of other sites, primarily respiratory secretions.In two of three patients infected with nontypable organisms, resistance appeared to emerge during therapy with ampicillin. Measurement of β lactamase was a practical and accurate method for differentiating between ampicillin-sensitive and resistant strains. All ten of the β lactamase-positive isolates tested had minimal inhibitory concentrations (MIC) for ampicillin of 15 μg per ml, or less. In contrast 30 β lactamase-negative strains had MIC''s of 1.5 μg per ml, or less, of ampicillin. Our results indicate that ampicillin resistance has become a significant problem in the Central Valley of California and probably the entire state.     

流感嗜血杆菌的分型研究

目的分析同济医院分离的流感嗜血杆菌的生物学分型及荚膜基因分型,了解本地区分离的流感嗜血杆菌的主要流行株。方法2012年1月1日至2012年12月31日从华中科技大学同济医学院附属同济医院分离流感嗜血杆菌100株。根据脲酶、吲哚和鸟氨酸脱羧酶试验对流感嗜血杆菌进行传统的生物学分型,分为Ⅰ～Ⅷ八个生物型。回顾患者病史资料,分析生物学分型和流感嗜血杆菌所引起的疾病之间的关系。用流感嗜血杆菌荚膜编码基因（bexA）和a—f型特异性荚膜基因设计引物,采用PCR技术对流感嗜血杆菌进行荚膜基因检测。通过生物学分型和荚膜基因分型结果的比对,探讨两者之间的关联。结果分离的100株流感嗜血杆菌生物学分型结果如下：Ⅲ型6株,Ⅳ型28株,Ⅴ型1株,Ⅵ型54株,Ⅶ型11株。未分离到Ⅰ型、Ⅱ型和Ⅷ型。分析患者的临床诊断,发现主要流行株Ⅵ型流感嗜血杆菌主要引起患者肺炎（包括支气管肺炎和新生儿肺炎）和支气管炎（包括毛细支气管炎和喘息性支气管炎）。荚膜基因分型结果显示,未分离到b型和b-型流感嗜血杆菌。共分离到1株f型,其余99株均为无荚膜抗原的不可分型流感嗜血杆菌。生物学分型和荚膜分型之间无明显的相关性。结论该院分离的流感嗜血杆菌主要为生物型Ⅵ型。回顾患者病史,发现Ⅵ型主要引起肺炎和支气管炎。荚膜基因分型显示,本地区分离的流感嗜血杆菌主要为不可分型流感嗜血杆菌。生物学分型和荚膜基因分型之间无明显相关性。     

Ampicillin resistance and penicillin-binding proteins of Haemophilus influenzae

Penicillin-binding protein (PBP) alterations have been associated with non-beta-lactamase-mediated ampicillin resistance in Haemophilus influenzae. We evaluated the PBP profiles of several ampicillin-susceptible and -resistant clinical isolates of H. influenzae to determine how consistently the described alterations occurred, and to document the reproducibility of the PBP profiles for this species. The MIC of ampicillin ranged from 0.06 to 0.13 microgram ml-1 for the susceptible isolates at an inoculum of 100,000 c.f.u. when tested by broth dilution, and was 0.5 microgram ml-1 for all four isolates when tested by agar dilution. The MIC for the resistant isolates ranged from 4 to 8 micrograms ml-1 when tested by broth dilution, and from 1.5 to 16 micrograms ml-1 when tested by agar dilution. At least eight distinct PBPs with molecular masses ranging from 27 to 90 kDa were detected both in cell membrane preparations and whole cell (in vivo) binding assays done on cells in the exponential growth phase. PBP variability was evident both in the ampicillin-susceptible and -resistant isolates; however, much greater variability existed within the four resistant strains. The differences in PBP patterns included (1) electrophoretic mobility, (2) binding capacity for the antibiotic and (3) the presence of additional PBPs in two of the resistant isolates. However, decreased binding capacity was consistently demonstrated in PBP 5 (56 kDa) of all of the resistant isolates. Saturation curves with both penicillin and ampicillin indicated that PBP 5 had decreased affinity for the antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surveillance of Haemophilus influenzae serotypes and antimicrobial resistance in Colombia, 1994-2002

Invasive disease caused by Haemophilus influenzae serotype b results in high rates of morbidity and mortality among children. In 1994, the Microbiology Group at the Instituto Nacional de Salud (Colombia) initiated a program to detect antimicrobial resistance in H. influenzae. Invasive isolates were collected by hospitals and public health laboratories as part of surveillance programs for acute respiratory infections and acute bacterial meningitis. To determine the evolution of serotypes and antimicrobial resistance patterns, invasive H. influenzae isolates collected from 1994 to 2002 were compared, and the impact of Hib conjugated vaccine in Colombia was reassessed. The analysis included 683 isolates, 379 (55.5%) were recovered from male patients, 370 (54.2%) from children under one year, 227 (33.2%) from children aged 1 to 5, 19 (2.8%) from children aged 6 to 14, and 38 (5.6%) from children over 14 years; 29 (4.2%) with no age data. Clinical classification recorded 493 (72.2%) of the samples were from patients with meningitis, 181 (26.5%) with pneumonia, and 9 (0.9%) with other diseases. Eighty five percent of isolates corresponded to H. influenzae serotype b, 12.9% were non capsular, and 2.0% corresponded to other serotypes (10 a, 1 d, 1 e and 2 f). Of the total number of isolates, 12.0% produced beta lactamase, 13.9% were resistant to ampicillin, 12.7% to trimethoprim sulfamethoxazole (SXT), 5.4% to chloramphenicol, 1% to cefuroxime. All isolates were susceptible to ceftriaxone. During the 10-year period, resistance to SXT increased from 5% to 13%. A significant decrease in meningitis cases was detected among children under one-year old and in the 1 to 5 age group. Before introducing the vaccine, an annual average of 43 and 23 isolates for each of these groups were received. During 2002, 10 and 6 isolates, respectively, were received for each group. Surveillance of invasive H. influenzae isolates has allowed the evaluation of Hib vaccine impact, as well as the detection of an increase of non-capsular isolates, and changes in resistance patterns.     

Infectivity and resistance to antibiotics of bacterial strains isolated from patients hospitalised in intensive care units

The aim of this study was to evaluate the frequency of isolation and antimicrobial resistance testing of bacterial strains isolated from clinical specimens from patients hospitalized in three Intensive Care Units in Wroc?aw. The susceptibility of bacteria (107 strains) to selected antibiotics was determined. The results clearly show that non-fermentative rods were identified as the main agents causing pneumonia (58% of isolates). The second commonest pathogens were Gram-positive cocci (29%). The P. aeruginosa and E. cloacae strains were resistant to ampicillin, amoxicillin/clavulanate, cefuroxime and cefotaxime. All isolates of A. baumanii were susceptible only to imipenem. The rods of K. pneumoniae and E. coli were resistant to ampicillin, about 55% strains of both bacteria were sensitive to other antibiotics, except piperacillin/tazobactam, imipenem and ciprofloxacin. About 90% of methicillin resistant S. epidermidis strains were resistant to all antibiotics, except vancomycin (100% isolates were sensitive). ESBL were detected among E. cloace, K. pneumoniae and E. coli. We found P. aeruginosa rods producing MBL.     

Haemophilus influenzae antibiotic resistant strains isolated in Moscow in 2002-2004]

The results of 3-year observation on emergence of H. influenzae antibiotic resistant strains in Moscow are summarized. The study included 566 strains isolated from patients in 2002-2004. The susceptibility was determined by the 2-fold microdilution method on the Haemophilus test medium. The percentage of the resistant strains isolated in 2002, 2003 and 2004 was the following: ampicillin --4.9, 3.2 and 3.6%, tetracycline--3.3, 3.2 and 1.8% and co-trimoxazole--10.9, 20.9 and 20% respectively. The strains isolated in 2003 and 2004 were resistant to azithromycin in 0.6 and 1.8% of the isolates and to clarithromycin in 1.3 and 3.2% of the isolates respectively. Five isolates differed by the minimum resistance to ampicillin whereas producing no beta-lactamase (BLNAR strains). The drugs of choice for the treatment of respiratory tract infections mainly due to H. influenzae, i.e. acute otitis and sinusitis, chronic bronchitis exacerbation and sometimes pneumonia remain betalactam antibiotics. From the microbiological viewpoint the inhibitor-protected aminopenicillins, cefuroxime and cefotaxime have no significant advantages vs. amoxycillin. The use of cotrimoxazole and chloramphenicol should be considered inexpedient.     

Frequency and distribution per species, biotypes, resistance to antibiotics and beta-lactamase production of the haemophils isolated from patients with respiratory diseases

A number of 150 samples were prelevated from respiratory tract secretions of 88 patients with respiratory infections and three healthy subjects; 162 haemophilus strains were isolated, identified and studied and the following results were obtained: H. parainfluenzae was isolated from tonsillitis and laryngitis--over 70%, bronchitis--58% and pharyngitis--56.6%; H. influenzae was isolated from pharyngitis--26.4%, bronchitis--16.1% and tonsillitis--13.6% cases; H. parahaemolyticus from bronchitis--19.3%, tonsillitis--13.6% and laryngitis. H. paraphrophilus was isolated (6.8%) from pharyngitis, tonsillitis, sinusitis, bronchitis and pulmonary abscess and H. paraphrohaemolyticus was isolated--4.5% from pharyngitis, synusitis, bronchitis and pulmonary sarcoidosis. Most of the isolates belonged to biotype II H. influenzae and biotypes II, I, III H. parainfluenzae. Haemophils were 100% sensitive to Ofloxacin and resistant to Cro--13.5%, Do--17.9%, C and Caz--22.2%, Aml--24.6%, Rd--40.7%, Amp--41.9% and Te--63.5%; varying according to the haemophilus species. H. influenzae was resistant to Do--14.2%, Caz and C--21.4%, H. parainfluenzae was resistant to Cro--11%, Do--22%, whilst H. parahaemolyticus was resistant to Do--9% and to Aml, Caz and Cro--13.6%. Haemophils isolated from sputum showed a resistance higher by 12-34% and 6-17% than those isolated from other specimens, such as pharyngeal exudate, where the resistance to rifadin was lower by 10%. beta-lactamases were present in 27.7% of the strains: H. parainfluenzae--36%, H. paraphrohaemolyticus--25%, H. influenzae--17.8% and H. parahaemolyticus--15.7%; in strains from sputum--34.2%, pharyngeal exudate--28.8% and from other specimens--6.6%. No correlations were noticed between the biotype and the clinical manifestation or the resistance to the antibiotic, a higher frequency of beta-lactamase production being reported in H. influenzae biotype V and H. parainfluenzae biotypes II and IV.     

Susceptibility of Haemophilus influenzae to antimicrobial agents used in Canada. Canadian Study Group.

We evaluated the incidence of Haemophilus influenzae resistance to selected antimicrobials used in Canada. From 1985 to 1987, 2503 H. influenzae isolates obtained in 14 hospitals across Canada were sent to the Centre hospitalier de l''université Laval (CHUL) for identification, serotyping, biotyping and testing for beta-lactamase production. Susceptibility tests were done with the use of 12 antibiotics. Of the strains 424 (16.9%) produced beta-lactamase; the proportion varied from 12.8%, in Newfoundland, to 19.6%, in Ontario. Of the strains 18.3% were type b; 19.4% of those produced beta-lactamase. Almost 82% of the strains were not type b. The proportion of beta-lactamase-producing strains varied according to the isolation site, from 15.3% in the respiratory tract to 25.6% in the blood. The overall level of resistance was 19.3% to ampicillin, 24.2% to erythromycin, 3.8% to trimethoprim-sulfamethoxazole, 1.7% to amoxicillin-potassium clavulanate, 1.4% to cefaclor, 1.3% to tetracycline, 1.0% to rifampin, 0.7% to cefuroxime and 0.1% to cefamandole. Disc diffusion susceptibility testing revealed 64 strains (2.6%) that did not produce beta-lactamase but were resistant to ampicillin and 9 (0.4%) that produced beta-lactamase but were susceptible to ampicillin. The results of beta-lactamase production tests were identical regardless of whether the tests were done by the CHUL or by the other hospitals, but there was a marked difference in the susceptibility test results between the CHUL and the other centres. Our results suggest that the level of resistance of H. influenzae to antibiotics is increasing in Canada and that the initial choice of drug therapy may have to be modified.     

Antimicrobial susceptibility of cerebrospinal isolates from patients with meningitis

Str. pneumoniae isolates were susceptible to penicillin, all to also ofloxacin and chloramphenicol and cefotaxim and 39 (100%) to cotrimoxazol. Concerning S. aureus, all isolates 22 were susceptible to oxacillin and chloramphenicol, and 21 also to cotrimoxazol. All N. meningitidis isolates but one-10 of all were susceptible to penicillin, all to cefotaxim, chloramphenicol and cotrimoxazol. All H.influenzae isolates were susceptible to ampicillin and chloramphenicol, as well as to ofloxacin and cotrimoxazol. Those surprisingly high susceptibilities to rather "old" antibiotics may be explained by low antibiotic consumption, accessibility and therefore low usage which is a key promoter of resistance both in community and hospital.     

Physical size of the donor locus and transmission of Haemophilus influenzae ampicillin resistance genes by deoxyribonucleic acid-mediated transformation.

The properties of donor deoxyribonucleic acid (DNA) from three clinical isolates and its ability to mediate the transformation of competent Rd strains to ampicillin resistance were examined. A quantitative technique for determining the resistance of individual Haemophilus influenzae cells to ampicillin was developed. When this technique was used, sensitive cells failed to tolerate levels of ampicillin greater than 0.1 to 0.2 mug/ml, whereas three resistant type b beta-lactamase-producing strains could form from the colonies in 1- to 3-mug/ml levels of the antibiotic. DNA extracted from the resistant strains elicited transformation of the auxotrophic genes in a multiply auxotrophic Rd strain. For two of the donors, transformation to ampicillin resistance occurred after the uptake of a single DNA molecule approximately 104-fold less frequently than transformation of auxotrophic loci and was not observed to occur at all with the third. The frequency of transformation to ampicillin resistance was two- to fivefold higher in strain BC200 (Okinaka and Barnhart, 1974), which was cured of a defective prophage. All three clinical ampicillin-resistant strains were poor recipients, but the presence of the ampicillin resistant genes in strain BC200 did not reduce its competence. Sucrose gradients of DNA from ampicillin-resistant transformants of BC200 and from the original ampicillin-resistant strains showed that: (i) all the DNA preparations had high molecular weights; (ii) donor activity for ampicillin resistance sedimented heterogeneously and in parallel with genome DNA up to the highest molecular weights observed (100 x 106 to 200 x 106); and (iii) genetic transformation of ampicillin resistance from strain BC200-amp90383 required the physical integrity of a linearly integrated segment of DNA having a molecular weight of about 25 x 106 to 30 x 106.     

The isolation and characterization of Campylobacter jejuni subsp. jejuni from domestic geese (Anser anser)

AIMS: The objectives of this study were to determine the presence of thermophilic Campylobacter spp. in free range domestic geese, and to characterize isolated strains using phenotyping criteria and SDS-PAGE of whole-cell proteins. METHODS AND RESULTS: Forty cloacal swabs from two different flocks of domestic geese were examined. All Camp. jejuni strains isolated from geese were biotyped using the Lior biotyping scheme. Twelve Camp. jejuni isolates were also tested for their susceptibility to 17 different antibacterial agents by a disc diffusion METHOD: Fourteen of the isolates were also subjected to SDS-PAGE. All of the geese examined were found to harbour Camp. jejuni. Six geese carried more than one species of Campylobacter. All strains examined were susceptible to various antibiotics but resistant to penicillin G and cephalothin. Eleven strains (92%) were resistant to sodium cefuroxime, and eight (67%) were resistant to cloxacillin, ampicillin and colistin sulphate. Three strains (25%) were resistant to tetracycline, and one strain was resistant to sulfamethoxazole/trimethoprim and kanamycin. Nine strains were subtyped as Camp. jejuni subsp. jejuni biotype II and the remaining ones as biotype I. There were 96% and 100% similarities between all the strains examined by SDS-PAGE. CONCLUSION: This study showed that Camp. jejuni were common in the intestinal tract of domestic geese. SIGNIFICANCE AND IMPACT OF THE STUDY: Geese should be considered as potential reservoirs for human and animal campylobacteriosis. The antibiotic resistance data from this study also showed that fluoroquinolone resistance, which appears to be a problem in poultry isolates in some countries, is not yet a problem in these geese.     

Effects of dietary chlortetracycline on the antimicrobial resistance of broiler faecal Streptococcaceae

A breeder flock and a control group of progeny birds were fed antimicrobial-free rations; a second group of progeny received rations supplemented with 50 g chlortetracycline (Ctc)/ton. Effects of dietary Ctc on the distribution of species and biotypes of faecal Gram-positive cocci and their relative resistance to 12 antimicrobial agents were studied. Antimicrobial resistance (AMR) pattern diversity and modal AMR patterns were determined for bacterial species common to all three groups. Numerical taxonomic analysis placed 1321 (97%) of 1360 isolates into eight species or biotypes. The largest cluster (n = 659, 48%) was a biotype of Streptococcus faecalis. Three clusters were biotypes of Streptococcus faecium and contained 580 isolates (42%). The isolates were susceptible to ampicillin and almost uniformly resistant to methicillin, neomycin, streptomycin, sulfadiazine and tetracycline. There were 54 and 47 different AMR patterns, including 0 to 11 and 1 to 11 resistance determinants, in isolates from control and Ctc-fed birds, respectively. Modal AMR patterns for Strep. faecalis and one biotype of Strep. faecium were very similar for all three groups of birds. However, modal patterns in a second biotype of Strep. faecium varied considerably for all three groups. Interpretation of AMR pattern diversities were equivocal among biotypes from both progeny groups. The variable distribution of isolates, proportions of resistant strains, modal patterns and diversity indices among the progeny were probably due to their exposure to different environmental sources of bacteria.     

Effects of dietary chlortetracycline on the antimicrobial resistance of broiler faecal Streptococcaceae

A breeder flock and a control group of progeny birds were fed antimicrobial-free rations; a second group of progeny received rations supplemented with 50 g chlortetracycline (Ctc)/ton. Effects of dietary Ctc on the distribution of species and biotypes of faecal Gram-positive cocci and their relative resistance to 12 antimicrobial agents were studied. Antimicrobial resistance (AMR) pattern diversity and modal AMR patterns were determined for bacterial species common to all three groups. Numerical taxonomic analysis placed 1321 (97%) of 1360 isolates into eight species or biotypes. The largest cluster ( n = 659, 48%) was a biotype of Streptococcus faecalis. Three clusters were biotypes of Streptococcus faecium and contained 580 isolates (42%). The isolates were susceptible to ampicillin and almost uniformly resistant to methicillin, neomycin, streptomycin, sulfadiazine and tetracycline. There were 54 and 47 different AMR patterns, including 0 to 11 and 1 to 11 resistance determinants, in isolates from control and Ctc-fed birds, respectively. Modal AMR patterns for Strep. faecalis and one biotype of Strep. faecium were very similar for all three groups of birds. However, modal patterns in a second biotype of Strep. faecium varied considerably for all three groups. Interpretation of AMR pattern diversities were equivocal among biotypes from both progeny groups. The variable distribution of isolates, proportions of resistant strains, modal patterns and diversity indices among the progeny were probably due to their exposure to different environmental sources of bacteria.     

Antibiotic sensitivity of Haemophilus influenzae isolated from patients with inflammatory lung diseases

In 1980-1986 the sensitivity of 2,045 H. influenzae strains isolated from the bronchial contents of patients with inflammatory lung diseases were studied. This study revealed that 60-80% of H. influenzae cultures circulating in Leningrad were sensitive to tetracyclin, chloramphenicol and erythromycin. During the period of observation the tendency towards the decrease of the number of highly sensitive H. influenzae cultures and the increase of the number of strains resistant to all antibiotic preparations was followed. Most of H. influenzae strains isolated in Leningrad were sensitive to penicillin, oleandomycin and ampicillin. In 1983 the appearance of H. influenzae strains, multiresistant to antibiotics, was noted. In 1986 these strains constituted 4.5% of all isolated cultures.     

Nonencapsulated or nontypeable Haemophilus influenzae are more likely than their encapsulated or serotypeable counterparts to have mutations in their fucose operon

Population biology of Haemophilus influenzae can be studied by multilocus sequence typing (MLST), and isolates are assigned sequence types (STs) based on nucleotide sequence variations in seven housekeeping genes, including fucK. However, the ST cannot be assigned if one of the housekeeping genes is absent or cannot be detected by the current protocol. Occasionally, strains of H. influenzae have been reported to lack the fucK gene. In this study, we examined the prevalence of this mutation among our collection of H. influenzae isolates. Of the 704 isolates studied, including 282 encapsulated and 422 nonencapsulated isolates, nine were not typeable by MLST owing to failure to detect the fucK gene. All nine fucK-negative isolates were nonencapsulated and belonged to various biotypes. DNA sequencing of the fucose operon region confirmed complete deletion of genes in the operon in seven of the nine isolates, while in the remaining two isolates, some of the genes were found intact or in parts. The significance of these findings is discussed.     

Human serum bactericidal activity against Haemophilus influenzae type b

We examined bactericidal and opsonizing activity of pooled adult 'immune' serum against Haemophilus influenzae type b with and without the addition of phagocytes. Four type b strains from cerebrospinal fluid (CSF) and three such strains from the nasopharynx (NP) of healthy children were examined. Duplicate reaction mixtures contained organisms in exponential (E) or stationary phase (S) of growth, serum, a complement source (human agammaglobulinaemic serum), and culture medium (bactericidal assay); separate assays contained the above components and polymorphonuclear leucocytes (opsonization system). A decrease in bacterial density of greater than or equal to 1 log10 unit was considered significant. All four S-CSF strains, three of four E-CSF strains and one of three S-NP strains were sensitive to the bactericidal activity of pooled serum. The other E-CSF strain, two S-NP strains and all three E-NP strains were resistant to the bactericidal activity of pooled serum. Two of three E-NP strains were opsonized by pooled serum; the other strains resistant to the bactericidal activity of pooled serum were also resistant to opsonization. Bactericidal and opsonizing activity of serum from an immunized adult was greater than or equal to that of pooled serum against each strain. Assuming normal adults are immune to invasive H. influenzae type b infection, an experimental test reflecting this immunity is the bactericidal activity against CSF isolates tested in stationary phase. We conclude that protection against invasive disease due to H. influenzae type b appears more complex than the presence of bactericidal and opsonizing activity in serum.     

Increase in antibiotic resistance in Haemophilus influenzae in the United Kingdom since 1977: report of study group.

A survey of antibiotic resistance in Haemophilus influenzae was carried out in the United Kingdom with 25 laboratories participating. The incidence of resistance in the 1841 strains examined was: tetracycline 3.1%, ampicillin 6.2%, chloramphenicol 1.03%, trimethoprim 1.4%, and sulphamethoxazole 1.5%. Of the 115 strains resistant to ampicillin, 106 produced beta-lactamase. Seventy-nine strains were capsulate, none of which was chloramphenicol resistant, but nine produced beta-lactamase (11.4%). Comparison of these figures of antibiotic resistance with those from a similar survey performed in 1977 showed a significant increase in resistance of H influenzae to ampicillin, chloramphenicol, and trimethoprim.