Nontypeable Haemophilus influenzae in the elderly

Nontypeable Haemophilus influenzae pneumonia occurred in 12 patients older than 60 years in a 15-month period. These patients represented approximately 11% of the 104 elderly patients with bacterial pneumonia in whom transtracheal aspiration was performed. Eighty-five percent of H influenzae isolates (12/14) recovered from elderly patients with pneumonia were nontypeable. Nontypeable H influenzae pneumonia occurred in the community, in nursing homes, and in the hospital. Patterns of both bilateral patchy bronchopneumonia and dense lobar consolidation were seen on chest roentgenograms.

Adherence of Haemophilus influenzae to buccal epithelial cells

The role of adherence of Haemophilus influenzae to epithelial surfaces in the pathogenesis of infection is unknown. Fluorescent-antibody and radiolabeled adherence methods were adapted to study H. influenzae adherence to human buccal epithelial cells. By the fluorescent-antibody method, 19 of 21 (90%) nontypable H. influenzae strains were found to be adherent compared with 2 of 42 (5%) type b strains (P less than 0.0001). Using a radiolabeled adherence method, we found that 9 of 12 (75%) nontypable H. influenzae strains were adherent to buccal epithelial cells whereas only 3 of 32 (9%) type b strains were adherent (P = 0.001). Results of H. influenzae adherence examined by both methods correlated significantly (P = 0.01). H. influenzae adherence to adult pharyngeal, nasal, and buccal epithelial cells was comparable. Type b H. influenzae did not adhere to the buccal epithelial cells of well children, children with H. influenzae type b disease, or children with upper respiratory infections. In contrast, nontypable H. influenzae did adhere to the buccal epithelial cells of well children and children with upper respiratory infections. These observed in vitro differences in adherence between nontypable and type b H. influenzae strains may explain differences in colonization, pathogenesis, and types of infection due to nontypable and type b H. influenzae.

Differential complement resistance mediates virulence of Haemophilus influenzae type b

Studies were undertaken to gain insight into the virulence of type b in contrast to the other Haemophilus influenzae capsular types. A relationship was found between the comparative virulence of H. influenzae types in humans and their resistance to the bactericidal effect of antibody-free complement. Type b was most resistant to the bactericidal effect of complement. The other types could be divided into three groups based upon their susceptibility to complement; this grouping was also related to their structural similarities. No association between virulence and either the biotype, source of isolate, in vitro association with peripheral polymorphonuclear leukocytes, or the total amount of capsular polysaccharide was found. However, among the type b strains, higher levels of cell-associated polysaccharide were associated with increased resistance to complement. The relative virulence of the six H. influenzae types in the infant rat model was generally similar to that in humans. After intraperitoneal challenge, type b and type a strains had the lowest 50% effective doses for bacteremia, removed by several logs from the values of the other types. By intranasal challenge, type b strains produced higher rates and levels of bacteremia than did type a strains. High levels of natural bactericidal antibodies to types c and e were found in adult female rats; this finding alone could not account for the differences in virulence among the H. influenzae types in the infant rat model. We propose that the virulence of type b strains is due to their greater resistance to the bactericidal activity of serum complement alone. Resistance to type b disease requires serum antibody to induce the complement-mediated reaction.

Typing of Haemophilus influenzae by coagglutination and conventional slide agglutination

Coagglutination was compared with conventional slide agglutination for the typing of 297 clinical isolates of Haemophilus sp. A 100% correlation was found with the H. influenzae type b isolates. Coagglutination showed no false-positive reactions with the nontypable strains of H. influenzae and H. parainfluenzae isolates; however, conventional slide agglutination exhibited many false-positive and non-interpretable reactions.

Ampicillin treatment failure of apparently beta-lactamase-negative Haemophilus influenzae type b meningitis due to novel beta-lactamase

Documented ampicillin treatment failures of systemic Haemophilus influenzae type b infections have been associated with synthesis of a TEM-1 beta-lactamase. A patient with H. influenzae type b meningitis in whom ampicillin treatment failed is described; the isolate was beta-lactamase-negative according to the cell suspension chromogenic cephalosporin assay. The false-negative result occurred in a strain which elaborated a novel, plasmid-mediated beta-lactamase with characteristics which distinguish it from TEM-1 beta-lactamase. Clinically important ampicillin resistance in H. influenzae type b occurs by mechanisms other than by synthesis of TEM-1 beta-lactamase. Diagnostic microbiology laboratories should perform antibiotic susceptibility tests in addition to tests for beta-lactamase production.

Biochemical characterization of Haemophilus species with the minitek differentiation system

Characterization of 102 Haemophilus strains by the Minitek differentiation system (BBL Microbiology Systems, Cockeysville, Md.) was compared with that by the conventional method. The results obtained by the two methods were in good agreement (P less than 0.001; test of independence). Therefore, this system was found to be applicable for the identification of Haemophilus species in routine clinical bacteriology.

[Biochemical characterization of haemophilus-strains by using the API 20 E- and API 50e-testsystem (author's transl)]

The commercially available test systems API 20E and API 50E were used to characterize 74 reference strains and clinical isolates of Haemophilus influenzae, H. aegyptius, H. parainfluenza, H. paraphrophilus and H. paraphrohaemolyticus The strains were grown on chocolate agar followed by suspending some colonies colonies in proteose pepton medium, pH 7.6, supplemented with the X- and V-factors. The alkaline suspension was used to inoculate the cups of the test kits. The alkali of the medium did not influence the biochemical reactions of the bacteria and enabled elimination of false positive reactions, particularly with the indicator phenol red. The API-systems proved efficacious for the diagnosis and characterization of the strains as compared with conventional biochemical tests.

Haemophilus influenzae infections in adults: characterization of strains by serotypes, biotypes, and beta-lactamase production

One hundred three cases of bacteremia or meningitis due to Haemophilus influenzae in adults were evaluated. Among 96 episodes of bacteremia, 60% were due to pneumonia and 15% to genital-related infections; 10% had no apparent source of infection. Of 42 isolates serotyped in routine fashion by slide agglutination, 79% were reported as type b. In contrast, of 45 isolates from the same interval with confirmed serotyping (usually by counterimmunoelectrophoresis), only 29% were type b and 64% were nontypable; 26% had been misidentified by routine slide agglutination. The majority (85%) of confirmed typable strains were biotype I. Four (40%) of 10 nontypable obstetrical isolates belonged to the relatively rare biotype IV. Only 2% of isolates were ampicillin-resistant, despite a high resistance rate among pediatric isolates in the same communities. When serotyping is carefully performed, nontypable organisms appear to be the major cause of invasive H. influenzae disease in adults.

A comparison of conventional and Minitek systems for biotyping Haemophilus influenzae

Two hundred pediatric isolates of Haemophilus influenzae from various sources were biotyped using the media described by Kilian in parallel with the Minitek system. There was an excellent correlation (97.7%) between the two systems. Ninety-five per cent of blood and cerebrospinal fluid (CSF) isolates were biotype I. Biotypes II and III were most frequent among isolates from sources other than blood and CSF. Production of beta-lactamase was limited to biotype II in the blood and CSF isolates, but was fairly evenly distributed among the biotypes from other sources. The Minitek system is an acceptable alternative to conventional media for biotyping H. influenzae.

Increased sensitivity of a new coagglutination test for rapid identification of Haemophilus influenzae type b

A newly developed rapid coagglutination test for identifying Haemophilus influenzae type b organisms isolated from clinical specimens correlated 100% with the slide agglutination test but was 100- to 200-fold more sensitive.

Subtyping isolates of Haemophilus influenzae type b by outer-membrane protein profiles

Outer-membrane proteins from isolates of Haemophilus influenzae type b were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sarcosinate-insoluble membrane preparations contained one peptide with a molecular weight of 16,000 and four major peptides with molecular weights of 25,000-40,000. A peptide with a molecular weight of 49,000 (50,000 in some strains) was observed after the samples were heated at 100 C. Fifty-one isolates obtained from patients hospitalized with invasive diseases, primarily meningitis, could be subclassified into nine categories based on reproducible and clearly resolvable differences in the outer-membrane protein profiles. Five categories accounted for 92% of the isolates. Complete concordance was observed in subtypes of strains obtained from epidemiologically related cases and contacts. Thus, comparison of the major outer-membrane proteins of H. influenzae type b is a useful technique for investigating the transmission of the organism and may provide a basis for further immunologic characterization of the outer-membrane proteins.

[Repartition of Haemophilus influenzae biotypes responsible of purulent meningitis. (Study of 50 strains) (author's transl)]

The repartition of the Haemophilus influenzae biotypes responsible of meningitis in world were reviewed. In Senegal the vast majority of strains of Haemophilus influenzae isolated from CSF belonged to biotype I (94%), the biotypes II and IV were rarely encountered (respectively 4% and 2%). The biotypes of repartition in Africa is similar to this encountered in other world areas.

Assessment of Haemophilus influenzae type b opsonins by neutrophil chemiluminescence

A luminol-enhancement chemiluminescence assay and a radiolabeled uptake assay were developed to assess opsonins for Haemophilus influenzae type b. Opsonins in acute and convalescent sera from 17 children with H. influenzae type b meningitis, along with pooled normal human sera, were evaluated and compared with anti-polyribosephosphate antibody concentrations. Five children had a rise in the chemiluminescence-area under the curve for convalescent compared with acute sera. Patient chemiluminescence--area-under-the-curve values were significantly (P less than 0.05) more likely to exceed 50% of normal human serum values if sera contained greater than or equal to 0.1 microgram of anti-polyribosephosphate antibody per ml. Magnesium ethylene glycol tetraacetic acid chelation and heat inactivation of patient and normal human sera significantly (P less than 0.05) reduced chemiluminescence--area-under-the-curve activity. Thus, complement appears to contribute significantly to the opsonization of H. influenzae type b in sera of children. Two of nine children had increases in opsonins as assayed by 3H-labeled H. influenzae type b uptake. After natural systemic H. influenzae type b infection, young children are unable to respond acutely with an increase in anti-polyribosephosphate antibody or serum opsonic activity.

Outer membrane protein composition in disease isolates of Haemophilus influenzae: pathogenic and epidemiological implications

The outer membrane protein composition of 50 disease isolates of Haemophilus influenzae has been determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All strains, including 28 strains of serotype b, one strain each of serotypes a, c, d, e, and f, and 17 untypable strains, had an outer membrane protein composition typical of gram-negative bacteria, i.e., these membranes contained two to three dozen proteins with four to six proteins accounting for most of their protein content. Variation in the mobility of these major outer membrane proteins from strain to strain was common but not universal; the observed patterns provided useful data and new insight into the epidemiology of type b disease. The basic findings can be summarized as follows: (i) All 50 strains possessed three proteins (one minor and two major) each having identical mobilities. The other proteins, both major and minor, varied in mobility. (ii) All type b strains possessed a fourth (major) protein of identical mobility. (iii) The 28 type b strains, on the basis of the mobility of the six major outer membrane proteins, could be divided into eight subtypes. Of all the other strains examined, both typable and untypable, only the serotype a strain belonged to one of these subtypes. (iv) The untypable strains showed considerable variation in the mobilities of their major outer membrane proteins. Of these 17 strains, 13 had an additional major outer membrane protein not present in encapsulated strains. (v) The outer membrane protein composition of a single strain remained unchanged after many passages on solid media, but varied with the growth phase. (vi) The outer membrane protein composition of isolates obtained from nine patients during an epidemic of type b meningitis varied, indicating that a single strain was not responsible for the epidemic. At least five different strains were responsible for these nine cases. (vii) Identical outer membrane protein compositions were observed in the following: in a type b strain and a mutant of this strain deficient in capsule production, indicating that the level of capsule synthesis is not obviously related to outer membrane protein composition; in type b strains isolated from different anatomic sites of patients acutely ill with meningitis, indicating that the strain associated with bacteremia is the same as that isolated from the cerebrospinal fluid; in type b strains isolated from siblings who contracted meningitis at about the same time, indicating infection with the same strain; and in type b strains isolated from the initial and repeat infection of a single patient, suggesting that reinfection was due to the same strain.

Biotypes of capsulated and non-capsulated Haemophilus influenzae. Correlation between biotypes and beta-lactamase production

396 Haemophilus influenzae strains were biotyped according to Kilian. 393 of the strains were assigned to biotypes I to V, while 3 strains remained unclassified. Eighty-nine per cent of the capsulated strains produced both urease and ornithine decarboxylase, biotypes I or IV, while 95 per cent of the non-capsulated strains produced only one of the enzymes, biotypes II, III, or V. Of consecutive strains from the upper respiratory tract, the incidence of beta-lactamase-positive strains was higher among capsulated than among non-capsulated strains (p less than 0.025). None of 133 non-capsulated beta-lactamase-positive strains produced both urease and ornithine decarboxylase, in contrast to 15 out of 147 non-capsulated beta-lactamase-negative strains (p less than 0.001). The type e strains were all of biotype IV and 3 of 7 consecutive strains were beta-lactamase-positive.

Non-type b Haemophilus influenzae infections in adults with reference to biotype

We report three cases of serious non-group b Haemophilus influenzae infections. The significance of these isolates with respect to both biotypes and serotypes is discussed.

Rapid biochemical characterization of Haemophilus species by using the micro-ID

Biotyping of Haemophilus influenzae into five type and H. parainfluenzae into three types based on indole production, ornithine decarboxylase, and urease has been reported (M. Kilian, Acta Pathol. Microbiol. Scand. Sect. B 82:835--842, 1976). A commercially available test system designed for the 4-h identification of Enterobacteriaceae. Micro-ID, proved efficacious for the rapid biotyping of these two Haemophilus species. The nitrate reductase, indole production, ornithine decarboxylase, urease, and o-nitrophenyl-beta-D-galactopyranoside hydrolysis tests in Micro-ID correlated over 99% with conventional methodology. By utilizing the indole and o-nitrophenyl-beta-D-galactopyranoside tests it was possible, with 261 of 272 (96.1%) isolates, to distinguish H. influenzae from H. parainfluenzae. Cerebrospinal fluid isolates were over 90% H. influenzae biotype I, and conjunctival isolates were approximately 70% biotype II. Type b H. influenzae were predominantly biotypes I and II; these type b isolates were also overwhelmingly indole producers. Although over 90% of biotypes I and II have been reported to produce beta-lactamase, this was not confirmed by the small number of beta-lactamase producers encountered here. The 4-h Micro-ID should prove a useful mechanism, amenable to the routine clinical laboratory, for the further exploration of the association of Haemophilus with the site of isolation, antigenicity, and antibiotic resistance.

Haemophilus influenzae infections in Fresno County, California: a prospective study of the effects of age, race, and contact with a case on incidence of disease

A prospective, population-based study of the incidence of infections with Haemophilus influenzae in Fresno County, California, was conducted. The average annual incidence or meningitis was 5.18 cases per 100,000 population, and of other invasive infections, 3.48 cases per 100,000. Incidence rates were highest in infants, but 13% of infections and five of seven deaths were in adults, primarily in elderly individuals with compromised defenses. Black children four years of age and younger were more susceptible to meningitis due to H. influenzae than were white children (P less than 0.001). In contrast, the increased incidence of haemophilus disease in Hispanic children was primarily a result of invasive infections other than meningitis (P less than 0.03). The secondary attack rate in household contacts less than two years of age was one in 24 during the first 30 days, one in 23 between 31 and 60 days, and 0.25 in 22 per month between three and six months. Age and racial factors may affect susceptibility to different forms of invasive disease due to H. influenzae, and young contacts of a patient are at increased risk of developing illness.

Serotypes and biotypes and antibiotic susceptibility of Haemophilus influenzae encountered in a clinical laboratory in Taiwan

Forty-four serologically and biochemically typable Haemophilus influenzae isolates from clinical specimens in Taiwan were subjected to analysis in their relationship with source of isolation and age distribution. It was found that all isolates from blood and cerebrospinal fluid were serotype b, biotype I, and all were in children less than 4 years of age. Serotypes b and e, biotypes I and III were encountered to have the highest incidence of infection caused by H. influenzae in this area. All H. influenzae isolates were further tested for susceptibility to several selected antibiotics. All strains of this organism were susceptible to erythromycin and chloramphenicol. All but two strains were susceptible to tetracycline, whereas more strains were resistant to carbenicillin, gentamycin, keflin, and penicillin. Thirty-four percent strains were found to be resistant to ampicillin and all were beta-lactamase producer. No direct correlation between ampicillin resistance and serotypes or biotypes was recognized.

Meningitis due to Haemophilus influenzae type e biotype 4

Haemophilus influenzae type e biotype 4 was isolated from the cerebrospinal fluid of a 16-month-old child with meningitis. This is the first isolation, from a case of meningitis, of this organism that has been biotyped.

Serological grouping of meningococci and encapsulated Haemophilus influenzae strains by latex agglutination

The latex agglutination method, utilizing antibody-coated latex particles, was adapted for serogrouping of Neisseria meningitidis and serotyping of encapsulated Haemophilus influenzae strains from agar plates. It was found to give more clear-cut results than conventional slide agglutination. A 100% agreement with the antiserum agar method was found for all strains isolated from blood or cerebrospinal fluid. Many meningococcal strains from nasopharyngeal carriers are autoagglutinable, but some of these gave a positive reaction with the group B latex reagent, although they were negative by the antiserum agar method. The latex agglutination method has several advantages over others: the lack of autoagglutination, easy performance, easy interpretation, and very low consumption of antisera.

Biotypes of Haemophilus encountered in clinical laboratories

The biochemical characteristics of 464 strains of Haemophilus influenzae and 83 strains of Haemophilus parainfluenzae isolated over an 18-month period are described. Of 22 characteristics obtained, only 6 were necessary to biochemically identify and biotype the isolates. The key substrates or tests were urease, ornithine, indole, o-nitrophenyl-beta-D-galactopyranoside, sucrose, and xylose. Five biotypes of H. influenzae and four of H. parainfluenzae were commonly recognized. Some strains were encountered which could not be accommodated in the recognized taxa but which constituted separate biotypes of the two species, H. influenzae biotype I was recovered principally from blood, cerebrospinal fluid, and upper respiratory secretion, and biotypes II and III were recovered from eye and sputum cultures. Biotype I was recovered primarily from children less than 1 year of age, whereas biotypes II and III were from persons 1 to 5 years old and from those over 20 years of age. Multiple isolates recovered from the same patient were almost always of the same biotype. Strains of H. parainfluenzae were isolated primarily from sputum, with others being isolated from body sources such as dental abscesses, gastric aspirates, and peritoneal fluid. An inverse relationship was noticed between hemolysis and mannose fermentation among H. parainfluenzae biotype III strains, whereas the relationship was absent among the other biotypes.

Methods for serotyping nasopharyngeal isolates of Haemophilus influenzae: slide agglutination, Quellung reaction, countercurrent immunoelectrophoresis, latex agglutination, and antiserum agar

Nasopharyngeal isolates of H. influenzae were typed by the slide agglutination test, the Quelling reaction, the latex agglutination test, countercurrent immunoelectrophoresis, and the antiserum agar test. These tests gave essentially comparable results, with countercurrent immunoelectrophoresis and latex agglutination being slightly more sensitive. Cross-reactive problems encountered with latex agglutination and the expense of performing countercurrent immunoelectrophoresis or the antiserum agar test made these tests less practical than the slide agglutination test to identify single strains that were already isolated. The Quellung reaction and slide agglutination were the most rapid tests used to type an organism. For mass screening of multiple samples, countercurrent immunoelectrophoresis was the simplest technique. The antiserum agar test was slow but was the best technique to screen nasopharyngeal swab cultures to identify the presence of any encapsulated strains in the mixed flora. Whether any of the above techniques were as sensitive as the immunofluorescence test was not evaluated in this study.

Biochemical characteristics of 130 recent isolates from Haemophilus influenzae meningitis

A total of 130 Haemophilus strains, comprising virtually all isolates from Danish and Norwegian cases of Haemophilus meningitis occurring in the period from October 1975 through September 1976, were examined by biochemical and serological means. All isolates were identified as H. influenzae and, except for one noncapsulated strain, possessed a capsule of serotype b. The vast majority of strains (93%) belonged to biotype I, which, in contrast to biotypes II and III, is rarely encountered as a commensal of the upper respiratory tract. This finding is a strong incentive for studies of possible additional virulence factors associated with biotype I organisms. The results are discussed in the light of North American reports, which have suggested changes in the etiology of Haemophilus meningitis.

Haemophilus influenzae Type D meningitis

This report describes an unusual pathogen associated with post-traumatic meningitis. Haemophilus influenzae type D was isolated from both cerebrospinal fluid and blood of this patient with meningitis.

Biochemical characteristics of Haemophilus influenzae in relationship to source of isolation and antibiotic resistance

Based on a limited number of biochemical properties, a system for biotyping Haemophilus influenzae (M. Kilian, Acta Pathol. Microbiol, Scand. Sect. B82:835-842, 1976) was used to analyze the relationship of biotype to source of infection and antibiotic resistance for 600 clinical strains. The distribution of biotypes from bacteremic patients was significantly different (P less than 0.001) from the distribution of biotypes from nonbacteremic patients. Although there appeared to be a correlation between biotype and source of isolation, no single biotype correlated with a specific clinical syndrome in bacteremic patients. The frequency of resistance to antibiotics (ampicillin, tetracycline, chloramphenicol, and kanamycin), which was known to be at least in part plasmid mediated, was determined. Of the 600 isolates, 43 were resistant to at least one antibiotic (30 were ampicillin resistant, 11 were tetracycline resistant, 1 was ampicillin-tetracycline resistant, and 1 was tetracycline-chloramphenicol resistant). Of these 43 resistant isolates, 42 were either biotype I or II. This distribution of biotypes among antibiotic-resustant isolates was significantly different from the overall distribution of biotypes (P is less than 0.001).

Use of the Minitek system for biotyping Haemophilus species

The Minitek system was used for characterization and identification of Haemophilus. The system was simple to use and provided rapid and clear-cut test results.

On the nature of nontypable Haemophilus influenzae

193 Haemophilus cultures, including 71 nontypable H. influenzae isolates, were examined with respect to phage HP1 sensitivity, lysogeny for this and for other phages and for excretion of bacteriocins. Fifty of the 71 nontypable cultures were sensitive to phage HP1 but only three produced plaques. The other 47 isolates were thus probably not non-encapsulated derivatives of H. influenzae serotypes a, b, d, and e, which have discrete and characteristic phage HP1 restriction and modification systems, or serotype c which appears to be restriction negative. They could be derivatives of serotype f which does not give plaques with phage HP1. The nontypable three cultures that plated phage HP1 efficiently could be non-encapsulated serotype c derivatives. Fourteen of the phage HP1 insentitive non-typable cultures were found to be defectively lysogenic for this phage. Five of these were genetically transformed to wild type lysogens. Their phage produced plaques efficiently only on Rc strains and on a restriction-negative mutant of serotype d. These lysogenic nontypable isolates are thus modification (and restriction) negative and they are thus probably not nonencapsulated derivatives of serotypes a, b, d, e, or f. Fifty three of 56 serotype b cultures were found to excrete a bacteriocin, to which all other nonproducing Haemophilus cultures were more or less sensitive. The three restriction-negative nontypable H. influenzae cultures also excreted this bacteriocin but the other cultures listed did not do this. The tentative conclusion from this study is that nontypable H. influenzae isolates are probably not derivatives of the six known encapsulated strains.

Incidence of ampicillin-resistant Hemophilus influenzae in otitis media

Ampicillin resistance in Hemophilus influenzae type b causing serious infections is appreciated, but little is known about ampicillin resistance in nonencapsulated strains causing otitis media. The ampicillin sensitivity of 984 middle-ear isolates of H. influenzae from children in Huntsville, Ala. obtained from 1970-1976, was examined: Nine AmpR isolates were found: one in 1973, two in 1974, three in 1975, and three in the first five months of 1976. Seven strains were nonencapsulated; two were type b. All nine produced beta-lactomase. The incidence of ampicillin resistance in strains causing otitis media increased from 0.6% in 1973 to 2.4% in 1976. AmpR H. influenzae infection should be suspected in situations where ampicillin therapy of otitis media is unsuccessful.

Meningitis due to Haemophilus influenzae type e

Haemophilus influenzae type e was isolated from the cerebrospinal fluid and blood of an 8-month-old child with meningitis.

The taxonomy of haemophili isolated from conjunctivae

The paper provides a description of 112 Haemophilus strains isolated from cases of conjunctivitis in Egypt, Tunisia, Denmark, and the U.S.A., and aims at a clarification of the taxonomy of haemophili implicated in conjunctivitis. Although the study confirms the diversity of haemophili which can be isolated from inflamed conjunctivae, the vast majority of strains could be assigned to either biotype II or III of H. influenzae. Thirteen strains possessed all the characteristics of the Koch-Weeks bacillus. However, judged by the findings the recognition of the Koch-Weeks bacillus as a separate species does not seem tenable. It is suggested that this organism is considered a haemagglutinating variety of H. influenzae biotype III. The study indicates that the haemagglutinating ability per se, which can be found in strains of several taxa of Haemophilus, is associated with a special pathogenic potential.

Quantitative antibiotic susceptibility testing: Haemophilus influenzae type B

Twelve strains of Haemophilus influenzae were tested for susceptibility to gentamicin, ampicillin, chloramphenicol and cephalothin using two methods, agar dilution and microdilution (broth). Although inocula and incubation conditions were standardized, significant differences in the minimal inhibitory concentration (MIC) were seen as a result of growth media. Method dependent differences were also observed for some antibiotics. Notwithstanding such variation, high level resistance of H. influenzae to ampicillin was readily detected by either broth or agar dilution tests.

Meningitis due to an unusual type of Haemophilus influenzae

An infant was admitted to hospital with suspected meningitis. Haemophilus influenzae type 'a' was isolated from cerebrospinal fluid (C.S.F.) and blood. Haemophilus meningitis due to types other than type 'b' is rare, and only a few due to type 'a' have so far been recorded. Investigations of the family are included together with a discussion of the implications for the diagnostic bacteriologist.

Competence mutants. 3. Responses to radiations

Class 3 com(-) mutants [normal in deoxyribonucleic acid (DNA) uptake but poor in ability to transform] were investigated with regard to ultraviolet (UV) and X-ray sensitivity of colony-forming ability and with regard to their ability to be transformed by UV- and X-ray-irradiated DNA. Three mutants, com(-)40, 60, and 78, were highly UV-sensitive in colony-forming ability. None of the mutants was more sensitive than wild type to UV-irradiated transforming DNA; in fact, six of the mutants showed considerably greater resistance. Two of the mutants (com(-)40 and 60) were slightly more sensitive to X ray in colony formation, whereas most of the mutants showed some degree of sensitivity to X-ray-irradiated transforming DNA. In addition, the physical fate of X-ray-irradiated transforming DNA has been examined, and in one case (com(-)48) there was a significant drop in sedimentation value of X-ray-irradiated donor DNA after uptake by recipient cells. The com(-) mutants analyzed have been classified on the basis of their UV and X-ray sensitivities, and, where appropriate, possible biochemical lesions have been implicated.

Serotyping of noncapsular Haemophilus influenzae

A microtechnique is described for agglutination typing of Haemophilus influenzae. It also provides a further means for classification and study of noncapsular type-specific strains.