Haemophilus influenzae causing conjunctivitis in day-care children

Microbiological profile of bacterial conjunctivitis in ibadan, Nigeria

OBJECTIVE

In bacterial conjunctivitis, clinical presentations are not diagnostic of the causative agent, therefore, microbiological analysis is mandatory for specific treatment option. This study was undertaken to determine the microbiology profile of bacterial conjunctivitis in our environment.

METHODOLOGY

This is a laboratory-based study carried out in the Medical Microbiology Laboratory of University College Hospital, Ibadan, Nigeria. Conjunctival swabs collected from 365 patients with clinically diagnosed conjunctivitis, were analysed by standard bacteriological methods.

RESULTS

Bacterial pathogens were detected in 342 (93.7%) conjunctival samples while 23(6.3%) were sterile. Of the pathogens, 256 (74.9%) were Staphylococcus aureus, 35(10.2%) Coagulase- negative staphylococci, 22 (6.4%) Pseudomonas aeruginosa , 11(3.2%) Escherichia coli, 7(2.1%) Klebsiella species, 5(1.5%) Streptococcus pneumoniae , 4(1.2%) Haemophilus influenzae, 1(0.3%) Proteus mirabilis, and 1(0.3%)Neisseria gonorrhoeae. The highest rate of conjunctivitis 96(26.3%) was found among infants and children (0-10years).Resistance rates to most of the tested antibiotics were high. However, 67% of them were susceptible to ceftriaxone while only 39.2% were susceptible to chloramphenicol.

CONCLUSION

This study has recorded high antibiotic resistance in bacterial pathogens of conjunctivitis in this environment; therefore, determining the susceptibility pattern of these pathogens to available antibiotics is crucial to effective management of bacterial conjunctivitis.

A multicenter comparison of polymyxin B sulfate/trimethoprim ophthalmic solution and moxifloxacin in the speed of clinical efficacy for the treatment of bacterial conjunctivitis

PURPOSE

To compare the speed of clinical efficacy for two currently available topical antibiotics: polymyxin B sulfate/trimethoprim (polymyxin/trimethoprim) and 0.5% moxifloxacin ophthalmic solution.

METHODS

Eighty-four eyes of 56 patients younger than 18 years with a clinical diagnosis of bacterial conjunctivitis were enrolled in this multicenter study. Patients were randomly assigned to receive either 1 drop of polymyxin/trimethoprim four times daily for 7 days or 1 drop of 0.5% moxifloxacin three times daily for 7 days. Ocular signs and symptoms were evaluated at baseline and 24 and 48 hours after the start of dosing. Microbiological cultures were collected at baseline and 48 hours. Patients rated ocular symptoms and adverse events on day 7 via telephone interview. Primary efficacy assessment included relief of all signs and symptoms of bacterial conjunctivitis.

RESULTS

All patients but one completed all visits. At the 48-hour visit, complete resolution of ocular signs and symptoms was observed in 81% of the patients treated with moxifloxacin and 44% of the patients treated with polymyxin/trimethoprim (P = .001). No adverse events were reported.

CONCLUSION

Moxifloxacin 0.5% administered three times daily is safe and cures bacterial conjunctivitis more effectively and significantly faster than polymyxin/trimethoprim dosed four times daily. The majority of patients were cured and symptom-free by 48 hours. Therefore, moxifloxacin is cost-effective and significantly more efficacious than polymyxin/trimethoprim in the speed by which it reduces the symptoms and disease transmission.

Acute bacterial conjunctivitis

Acute bacterial conjunctivitis is the eye disease most commonly seen by general practitioners, and is estimated to represent approximately 1% of all consultations in primary care. This article gives a review of the epidemiology, aetiology, clinical picture, complications, differential diagnoses, in vitro examinations and therapy of acute bacterial conjunctivitis. Until now, topical antibacterial therapy has generally been preferred by both physicians and patients because this will usually shorten the course of the disease slightly and allow the early readmittance of children to their kindergarten or school. Recently, several reports from primary care have confirmed the well-known clinical experience that the disorder has an excellent prognosis with a high frequency of spontaneous remission. In accordance, an expectant attitude or delayed prescription policy are now frequently strongly recommended. However, these reports also emphasize the difficulty in making a correct clinical distinction between bacterial and viral conjunctivitis. The effect of a general non-prescription attitude on transmission rates of pathogens also remains to be clarified. This must be born in mind when deciding how these patients should be handled. The socioeconomic and medical pros and cons of different treatment policies are discussed, and a highly personal view on the optimal handling strategy for these patients is also presented.

Comparative minimal inhibitory and mutant prevention drug concentrations of four fluoroquinolones against ocular isolates of Haemophilus influenzae

PURPOSE

Haemophilus influenzae is a known ocular pathogen, particularly in the pediatric population. The purpose of this study was to determine the minimal inhibitory concentration (MIC) and mutant prevention concentration (MPC) values of third-generation (i.e., ciprofloxacin and ofloxacin) and fourth-generation (i.e., gatifloxacin and moxifloxacin) fluoroquinolone antibiotics against clinical ocular isolates of H. influenzae.

METHODS

Twenty-six clinical isolates of H. influenzae were evaluated. For MIC testing, approximately 10(5) colony-forming units/mL of test organism was added to an H. influenzae test medium containing twofold dilution increments of each fluoroquinolone. Cultures were incubated for 18 to 24 hours at 35 degrees C to 37 degrees C in 5% CO2. The lowest drug concentration that prevented growth was recorded as the MIC. The lowest drug concentration that inhibited 90% of strains tested was recorded as the MIC90. To determine MPC values, more than 10(10) bacteria were inoculated to agar plates containing varying drug concentrations and incubated for 24 to 48 hours at 35 degrees C to 37 degrees C in 5% CO2. To confirm MPC values, bacteria isolated from drug-containing plates were subcultured to drug-free agar, incubated, and then subcultured to a plate with the same drug concentration. The lowest drug concentration that allowed no growth was recorded as the MPC.

RESULTS

All tested fluoroquinolones were highly active against H. influenzae. The MIC90 values were 0.016 microg/mL for gatifloxacin and ciprofloxacin and 0.031 microg/mL for moxifloxacin and ofloxacin. The MPC90 values were 0.125 microg/mL for gatifloxacin and 0.5 microg/mL for moxifloxacin, ofloxacin, and ciprofloxacin.

CONCLUSIONS

All evaluated fluoroquinolones were effective against H. influenzae. The MIC90 and MPC90 values for gatifloxacin were consistently lower than those for moxifloxacin.

Controlling contagious bacterial conjunctivitis

BACKGROUND

Recent outbreaks (epidemics) of Streptococcus pneumoniae conjunctivitis, involving hundreds of patients, underscore the importance of following recommended guidelines to minimize disease transmission. These include the use of antimicrobial agents capable of minimizing patients' symptoms and the duration of the infectious period when disease can be transmitted to others.

PURPOSE

To compare the amount of time required forvarious antibiotic solutions to kill S. pneumoniae, a common cause of bacterial conjunctivitis.

MATERIALS AND METHODS

Isolates of S. pneumoniae from three patients were exposed to selected ophthalmic antibiotic products: moxifloxacin 0.5%, tobramycin 0.3%, gentamicin 0.3%, and polymyxin B 10,000 IU-trimethoprim 1.0%. The products were diluted 1:100 and 1:1000 for testing. At 15, 30, 60, 120, and 180 minutes after exposure, aliquots of broth were withdrawn, the cells were separated and cultured, and the viable cell count was determined.

RESULTS

Moxifloxacin killed actively growing S. pneumoniae faster and to a greater extent than did the other three antibiotic products when tested at concentrations corresponding to tear film concentrations 5 to 10 minutes and 30 to 60 minutes after instillation of the products.

CONCLUSIONS

Moxifloxacin killed S. pneumoniae in vitro faster than did the other antibiotics. Consequently, its use should complement other generally accepted measures for minimizing patients' symptoms and limiting the contagiousness of bacterial conjunctivitis. Also, this is consistent with the recommendations of other investigators to prescribe the most recent generation of fluoroquinolone antibiotics for the specific purpose of limiting the spread of bacterial resistance.

An outbreak of conjunctivitis due to atypical Streptococcus pneumoniae

BACKGROUND

In February 2002, clinicians at the Dartmouth College Health Service recognized an outbreak of conjunctivitis; cultures of conjunctival swabs implicated Streptococcus pneumoniae. An investigation was begun to determine the extent of the outbreak, confirm the cause, identify modes of transmission, and implement control measures.

METHODS

Investigators reviewed the health service's data base for diagnoses of conjunctivitis. Viral and bacterial cultures were obtained from ill students. Bile-soluble isolates that were susceptible to ethylhydrocupreine (optochin) and therefore were presumed to be pneumococci underwent serotyping, capsular staining, pulsed-field gel electrophoresis, a DNA probe, and multilocus sequence typing. A cohort study of risk factors was conducted with the use of the Internet. Control measures included distribution of alcohol-based hand gel and messages about prevention.

RESULTS

Among 5060 students, 698 (13.8 percent) received a diagnosis of conjunctivitis from January 1, 2002, through April 12, 2002, including 22 percent of first-year students. Presumed pneumococci were isolated from 43.3 percent of conjunctival swabs (110 of 254); viral cultures performed on 85 specimens were negative. DNA probes and multilocus sequence typing confirmed that the organisms were pneumococci, although the bacteria did not have the characteristic capsule. On pulsed-field gel electrophoresis, strains were found to be identical to pneumococci that caused outbreaks of conjunctivitis in other parts of the country in 1980. Analysis of survey data from 1832 students indicated that close contact with a student with conjunctivitis, wearing contact lenses, membership on a sports team, and attending parties at or living in a fraternity or sorority house were associated with conjunctivitis. The rate of diagnosis of conjunctivitis declined after the implementation of control measures and after spring break.

CONCLUSIONS

This large outbreak of conjunctivitis on a college campus was caused by an atypical, unencapsulated strain of S. pneumoniae that was identical to strains that had caused outbreaks two decades earlier.

Haemophilus influenzae type b colonization in children in a hospital-based day care center

We sought to assess the effect of day care center (DCC) attendance and parental health care work environment on the prevalence of Haemophilus influenzae type b (Hib) pharyngeal colonization in children in Turkey. Children of health care workers were evaluated by nasopharyngeal culture specimens obtained prior to enrollment at a hospital-based DCC at Cerrahpasa Medical Faculty (CMF-DCC) and then again after 3 months of attendance. A larger cohort from this same DCC was evaluated after 6 months of attendance and compared to a group of children of non-health care workers enrolled in Bahcelievler-DCC. As is standard of care in Turkey, none of these children had received the Hib vaccine. Fifty children of health care workers were evaluated prior to their enrollment and then again after 3 months at CMF-DCC. The incidence of Hib carrier state at enrollment was 4% and increased to 22% after 3 months at the DCC. To assess the affect of parental health care employment on Hib carriage rates, 103 children from CMF-DCC and 40 children of non-medical families at Bahcelievler-DCC were evaluated. Hib carrier state was identified in 40.7 and 47.5% after more than 6 months of attendance at CMF-DCC and Bahcelievler-DCC, respectively. No significant difference was observed between carriage rates of children coming from medical and non-medical families and the average carriage rate was 42.6% when duration of day-care attendance exceeded 6 months. Our results demonstrate that Hib carriage rates are affected by the duration of DCC attendance. Parents' employment in a health care facility does not affect carriage rates.

Biotypes and serotypes of Haemophilus influenzae ocular isolates

AIM

To determine which subtypes of Haemophilus influenzae are most commonly associated with ocular disease, and whether the site of ocular H influenzae infection is correlated with specific subtypes of the organism.

METHODS

The biotypes and serotypes of ocular H influenzae isolates collected at the Francis I Proctor Foundation between March 1989 and January 2000 were examined. A total of 62 ocular isolates were retrieved from frozen storage and plated on chocolate agar. Biotypes were assigned based upon the ability of the isolates to produce indole, urease, and ornithine decarboxylase. Capsular subtypes a-f were determined by slide agglutination using commercially available subtype specific antisera. Identified biotypes and serotypes were then analysed with regard to site of infection.

RESULTS

Patient age ranged from 1 to 92 years with a median age of 45 years. 38 (61%) of the isolates were biotype II, 23 (37%) were biotype III, and one (2%) was biotype VII. All of the isolates were non-encapsulated and thus serologically non-typable. H influenzae biotype II was found in 28 of 48 (58%) conjunctivitis cases, five of eight (63%) keratitis cases, and two of two (100%) endophthalmitis cases. Biotype III was found in 20 of 48 (42%) conjunctivitis cases, two of eight (25%) keratitis cases, and a single case of dacryocystitis. Biotype VII was associated with one of eight (13%) keratitis cases.

CONCLUSION

Most ocular H influenzae isolates appear to be serologically non-typable strains from biotypes II and III, less virulent subtypes that frequently colonise the nasopharynx. In addition, the site of ocular H influenzae infections appears to be largely independent of species subtype.

Mapping of binding domains of nontypeable Haemophilus influenzae HMW1 and HMW2 adhesins

Nontypeable Haemophilus influenzae is an important cause of localized respiratory tract disease, which begins with colonization of the upper respiratory mucosa. In previous work we reported that the nontypeable H. influenzae HMW1 and HMW2 proteins are high-molecular-weight nonpilus adhesins responsible for attachment to human epithelial cells, an essential step in the process of colonization. Interestingly, although HMW1 and HMW2 share significant sequence similarity, they display distinct cellular binding specificities. In order to map the HMW1 and HMW2 binding domains, we generated a series of complementary HMW1-HMW2 chimeric proteins and examined the ability of these proteins to promote in vitro adherence by Escherichia coli DH5alpha. Using this approach, we localized the HMW1 and HMW2 binding domains to an approximately 360-amino-acid region near the N terminus of the mature HMW1 and HMW2 proteins. Experiments with maltose-binding protein fusion proteins containing segments of either HMW1 or HMW2 confirmed these results and suggested that the fully functional binding domains may be conformational structures that require relatively long stretches of sequence. Of note, the HMW1 and HMW2 binding domains correspond to areas of maximal sequence dissimilarity, suggesting that selective advantage associated with broader adhesive potential has been a major driving force during H. influenzae evolution. These findings should facilitate efforts to develop a subcomponent vaccine effective against nontypeable H. influenzae disease.

Impact of antimicrobial therapy on nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, and Branhamella catarrhalis in children with respiratory tract infections

We conducted a multicenter prospective study to document changes in nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, and Branhamella catarrhalis during antibiotic therapy. A cohort of 629 children with respiratory tract infections underwent nasopharyngeal sampling before and after antibiotic treatment. Susceptibility testing, serotyping, arbitrarily primed polymerase chain reaction, and pulsed-field gel electrophoresis were used to compare pretreatment and posttreatment strains of S. pneumoniae. A significant decrease in carriage of all 3 species (especially S. pneumoniae and B. catarrhalis) was recorded. The increase in the proportion of penicillin-resistant pneumococci (PRP; 66% vs. 44%) was due to the decreased carriage of penicillin-susceptible pneumococci (71 of 629 vs. 176 of 629). The risk of PRP carriage in a given child did not increase. None of the children was found to harbor genetically related strains with increased minimum inhibitory concentrations. Given the multiple resistance of PRP, beta-lactam antibiotic therapy also increased the incidence of macrolide-resistant strains, whereas macrolides selected both macrolide- and penicillin-resistant strains.

Haemophilus influenzae adherent to contact lenses associated with production of acute ocular inflammation

Ten episodes of adverse responses to contact lens wear, including contact lens-induced acute red eye (CLARE), in which Haemophilus influenzae was isolated from contact lenses and/or from one of the external ocular sites at the time of the event, are described. All episodes occurred in patients wearing disposable hydrogel lenses on a 6-night extended-wear schedule. Two of the patients had recurrent episodes. H. influenzae was usually isolated in large numbers, and other bacteria or fungi colonizing the contact lens or the external ocular surface were usually present in low numbers. Those patients who were colonized with H. influenzae were more than 100 times as likely to have had a CLARE or infiltrative response than those subjects who were not colonized with this bacterium. H. influenzae colonization of the contact lens and eye may be subsequent to colonization of the nasopharynx because four of the seven patients presented with fever at the time of the event, with concurrent upper respiratory tract infection. Contact lens wearers should be made aware of the potential risk of CLARE associated with the wearing of contact lenses for extended periods during and subsequent to upper respiratory tract infection.