Influenza guideline for South Africa--update 2008

OBJECTIVE

The South African Thoracic Society, in conjunction with interested stakeholders, published a Guideline for Influenza Management in Adults in 1999. This year the South African Thoracic Society (SATS) identified the need to revise that guideline for the following reasons: * To indicate the viral strains that are to be incorporated into the vaccine for the 2008 season * To add important new data regarding treatment of influenza * To add a section on influenza in children * To clarify issues in managing and preventing influenza in HIV-infected individuals.

INFLUENZA VIRUS

The influenza virus genus belongs to the family orthomyxoviridae. The haemagglutinin (HA) protein is the outermost protein, responsible for attachment to the host receptor, and is critical in determining the host's immune response to the virus. Changes in the antigenic epitopes of HA therefore allow the virus to escape the host's specific immune response. The genus is classified into three types, A, B and C, on the basis of the antigenic epitopes of the nucleoprotein (NP). Type A, which is widespread in nature in birds and mammals, is the most important type clinically and epidemiologically. It is further divided into subtypes on the basis of the antigenic epitopes of the HA and neuraminidase (NA) proteins. Each of the human subtypes H1N1, H2N2 and H3N2 are further subdivided into strains on the basis of more subtle antigenic properties of the HA protein.

INFLUENZA VACCINATION

Influenza vaccine is the mainstay of influenza prevention strategies. All persons who are at high risk of influenza and its complications because of underlying medical conditions or who are receiving regular medical care for conditions such as chronic pulmonary and cardiac disease, chronic renal diseases, neuromuscular diseases, diabetes mellitus and similar metabolic disorders, and individuals who are immunosuppressed (including HIV-infected persons with CD4 counts above 100 cells/microl and HIV-infected children with CD4 counts >15%), should be vaccinated. Vaccines should be given from at least 2 months prior to the onset of autumn (March in South Africa). The recommended vaccine formulation for 2008 is: * A/Solomon Islands/3/2006 (H1N1) (IVR-145) * A/Brisbane/10/2007 (H3N2) (IVR-147) * B/Florida/4/2006 or B/Brisbane/3/2007.

TREATMENT OF INFLUENZA

Influenza illness is characterised by the acute onset of systemic and respiratory signs occurring in autumn or winter. Recommendations for the Prevention and Control of Influenza have indicated that neither amantadine nor rimantadine should be used for the treatment or chemoprophylaxis of influenza A. NA inhibitors are an important adjunct to influenza vaccination, in both the prevention and treatment of influenza. Because of concerns about the possibility of the development of viral resistance with overuse of these agents, it is recommended that NA inhibitors in the treatment of influenza should be reserved for high-risk or sicker influenza patients.

Impact of conjugate Haemophilus influenzae type b (Hib) vaccine introduction in South Africa

OBJECTIVE

To analyse trends in reported invasive Haemophilus influenzae disease in South Africa within the first five years of introduction of conjugate Haemophilus influenzae type b (Hib) vaccine in the routine child immunization schedule.

METHODS

We used national laboratory-based surveillance data to identify cases of invasive H. influenzae disease between July 1999 and June 2004, and submitted isolates for serotyping and antimicrobial susceptibility testing.

FINDINGS

The absolute number of Hib cases (reported to the national surveillance system) among children below one year of age decreased by 65%, from 55 cases in 1999-2000 to 19 cases in 2003-04. Enhanced surveillance initiated in 2003, identified human immunodeficiency virus (HIV)-infection and incomplete vaccination as contributing factors for Hib transmission. The total number of laboratory-confirmed cases of H. influenzae remained unchanged because non-type b disease was being increasingly reported to the surveillance system concomitant with system enhancements. Children with non-typable disease were more likely to be HIV-positive (32 of 34, 94%) than children with Hib disease (10 of 14, 71%), P = 0.051. Recent Hib isolates were more likely to be multidrug resistant (2% in 1999-2000 versus 19% in 2003-04, P = 0.001).

CONCLUSION

Data from a newly established national laboratory-based surveillance system showed a decrease in Hib disease burden among South African children following conjugate vaccine introduction and identified cases of non-typable disease associated with HIV infection.

Surveillance of resistance in bacteria causing community-acquired respiratory tract infections

Bacterial resistance to antibiotics in community-acquired respiratory tract infections is a serious problem and is increasing in prevalence world-wide at an alarming rate. Streptococcus pneumoniae, one of the main organisms implicated in respiratory tract infections, has developed multiple resistance mechanisms to combat the effects of most commonly used classes of antibiotics, particularly the beta-lactams (penicillin, aminopenicillins and cephalosporins) and macrolides. Furthermore, multidrug-resistant strains of S. pneumoniae have spread to all regions of the world, often via resistant genetic clones. A similar spread of resistance has been reported for other major respiratory tract pathogens, including Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. To develop and support resistance control strategies it is imperative to obtain accurate data on the prevalence, geographic distribution and antibiotic susceptibility of respiratory tract pathogens and how this relates to antibiotic prescribing patterns. In recent years, significant progress has been made in developing longitudinal national and international surveillance programs to monitor antibiotic resistance, such that the prevalence of resistance and underlying trends over time are now well documented for most parts of Europe, and many parts of Asia and the Americas. However, resistance surveillance data from parts of the developing world (regions of Central America, Africa, Asia and Central/Eastern Europe) remain poor. The quantity and quality of surveillance data is very heterogeneous; thus there is a clear need to standardize or validate the data collection, analysis and interpretative criteria used across studies. If disseminated effectively these data can be used to guide empiric antibiotic therapy, and to support-and monitor the impact of-interventions on antibiotic resistance.

Antibiotic therapy of community respiratory tract infections: strategies for optimal outcomes and minimized resistance emergence

Widespread, increasing antibiotic resistance amongst the major respiratory pathogens has compromised traditional therapy of the major infective respiratory syndromes, including bacterial pneumonia and acute exacerbations of chronic bronchitis. Guidelines for antibiotic prescribing dating from the 1980s to 1990s, which attempted to address such problems, were commonly too prescriptive and difficult to apply, and took little account of end-user practice or locally prevalent resistance levels. Further confusion was caused by conflicting recommendations emanating from differing specialty groups. The evidence that such guidelines benefited either clinical outcomes or treatment costs has been disputed. They have probably had little effect on resistance emergence. We report the recommendations of an independent, multi-national, inter-disciplinary group, which met to identify principles underlying prescribing and guideline formulation in an age of increasing bacterial resistance. Unnecessary prescribing was recognized as the major factor in influencing resistance and costs. Antibiotic therapy must be limited to syndromes in which bacterial infection is the predominant cause and should attempt maximal reduction in bacterial load, with the ultimate aim of bacterial eradication. It should be appropriate in type and context of local resistance prevalence, and optimal in dosage for the pathogen(s) involved. Prescribing should be based on pharmacodynamic principles that predict efficacy, bacterial eradication and prevention of resistance emergence. Pharmacoeconomic analyses confirm that bacteriologically more effective antibiotics can reduce overall management costs, particularly with respect to consequential morbidity and hospital admission. Application of these principles should positively benefit therapeutic outcomes, resistance avoidance and management costs and will more accurately guide antibiotic choices by both individuals and formulary/guideline committees.

Aeromonas species isolated from medicinal leeches

Aeromonas hydrophila infections are a recognized complication of the use of medicinal leeches. The authors performed an experiment designed to find a safe and practical way to sterilize the leech gut of pathogenic organisms. Leeches were incubated for a 12-hour period in solutions of antibiotic effective against A. hydrophila. The incubations in the antibiotic solutions failed to eradicate pathogenic bacteria from the gut of the leeches. The authors examined cultures of bacteria isolated from the guts of the commonly used Hirudo medicinalis (European leech) and found a wide variety of pathogenic organisms. A. hydrophila is widely believed to be the most common enteric pathogen, but the authors found A. sobria more frequently in their experiment. They also cultured the guts of the leech H. michaelseni recently used clinically in South Africa. A. caviae was the most common pathogen encountered in these leeches. A. caviae and A. sobria cause a spectra of disease similar to A. hydrophila. The authors endorse the current recommendation that all patients who have leech therapy for congested flaps or replants receive broad-spectrum prophylactic antibiotics. This appears to be the safest and simplest way to prevent leech-related infections.

The impact of HIV on Streptococcus pneumoniae bacteraemia in a South African population

OBJECTIVES

To determine the impact of HIV infection on Streptococcus pneumoniae bacteraemia in adults and children by analysing the prevalence and clinical features of such diseases and determining the prevalent serotypes/serogroups and susceptibility patterns of isolates.

DESIGN

Patients were identified prospectively from January to October 1996.

SETTING

Chris Hani Baragwanath Hospital, Soweto, a tertiary referral hospital treating adults and children, in an urban district near Johannesburg, South Africa.

PATIENTS AND METHODS

All patients with S. pneumoniae isolated from blood culture by the Microbiology Department, Chris Hani Baragwanath Hospital were studied. Clinical and microbiological features were recorded.

RESULTS

A total of 178 patients with S. pneumoniae were investigated as part of the study; 49 were aged < 13 years. HIV seroinfection was present in 25 (51%) children and 58 (45%) adults. The incidence of S. pneumoniae bacteraemia was 36.9-fold increased in HIV-seropositive children and 8.2-fold increased in HIV-seropositive adults compared with HIV-seronegative individuals. Both adult and paediatric HIV-seropositive patients with S. pneumoniae bacteraemia were significantly younger than HIV-seronegative patients. Pneumonia was a significantly more common presentation in HIV-seropositive children, otherwise the spectrum of disease and outcome were similar in HIV-seronegative and positive groups. Serotype 1 S. pneumoniae isolates were significantly less common in HIV-infected individuals (both adults and children). Resistance to penicillin was increased in S. pneumoniae isolates from HIV-infected patients (significant in adults). Patients with penicillin-resistant isolates did not have a poorer outcome. The potential coverage of serotypes/serogroups included in the proposed nine-valent conjugate pneumococcal vaccine was 88% in HIV-seronegative children and 83% in HIV-seropositive children. The potential coverage of the currently available 23-valent pneumococcal vaccine for adults was 98.2 and 100)% for HIV-infected and HIV-uninfected adults, respectively.

CONCLUSION

The burden of bacteraemia due to S. pneumoniae in HIV-seropositive individuals admitted to our hospital is considerable. Differences in the S. pneumoniae serotypes/serogroups in HIV-infected patients have been demonstrated with resultant differences in antibiotic susceptibility patterns. Excellent potential for vaccine coverage was demonstrated for both HIV-seronegative and HIV-seropositive individuals. Further studies are necessary to test the clinical efficacy of pneumococcal vaccination of HIV-seropositive adults and children as a potential preventative measure against this prevalent disease.

Antibiotic susceptibility patterns of Streptococcus pneumoniae in china and comparison of MICs by agar dilution and E-test methods

Beta-lactam resistance by Streptococcus pneumoniae is becoming a significant threat to public health worldwide. However, data concerning antibiotic susceptibility patterns in China have not been published. In this study, a total of 79 clinical isolates and 244 nasopharyngeal isolates of S. pneumoniae were recovered between June and November 1997 in Beijing. The agreement between the MICs (+/-1 log2 dilution) of penicillin and ceftriaxone obtained by the agar dilution and E-test methods for the 79 clinical strains was very good (97.5 and 93.7%, respectively). Of these 79 strains, 9 (11.4%) were intermediate and 2 (2.5%) were resistant to penicillin. Of the 244 nasopharyngeal strains, 32 (13.1%) were intermediate and 3 (1. 2%) were resistant to penicillin. The total of 277 penicillin-susceptible clinical and nasopharyngeal isolates of Streptococcus pneumoniae were 100% susceptible to amoxicillin-clavulanic acid, cefuroxime, ceftriaxone, and cefotaxime. In the 35 penicillin-intermediate and -resistant nasopharyngeal strains, elevated MICs of amoxicillin-clavulanic acid, cefuroxime, ceftriaxone, and cefotaxime were seen for Collapse

Key Words Collapse

MESH Headings

• Agar
• Drug Resistance, Microbial
• Humans
• Microbial Sensitivity Tests/methods
• Nasopharynx/microbiology
• Streptococcus pneumoniae/drug effects

Collapse

Grants

• Wellcome Trust

Collapse

Nasopharyngeal carriage and antimicrobial resistance in isolates of Streptococcus pneumoniae and Haemophilus influenzae type b in children under 5 years of age in Botswana

OBJECTIVES

A prospective survey was conducted to determine the prevalence of asymptomatic nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae type b in children under 5 years of age in Botswana and to determine the antibiotic resistance patterns of these organisms to commonly used antimicrobial agents.

METHODS

Children 2 months to 5 years of age (n = 249) were recruited from outpatient clinics in Gaborone and Francistown, and 29 were sampled from the pediatric wards at Princess Marina (Gaborone) and Nyangabgwe (Francistown) Hospitals. Nasopharyngeal specimens were collected and the carriage and antibiotic resistance of S. pneumoniae and H. influenzae type b were determined. Analyses of risk factors associated with carriage and resistance were performed.

RESULTS

Streptococcus pneumoniae was isolated from 69% of the outpatient children in Gaborone and 85% of the children in Francistown; the carriage rate in hospitalized children was 36% and 33% in Gaborone and Francistown, respectively. Approximately half of the isolates at both sites were resistant to at least one antibiotic, the most common being cotrimoxazole and penicillin. Resistance to three or more antibiotics (multiple resistance) was found in less than 10% of the isolates. Most penicillin resistance at both sites was at the intermediate level; however, almost 20% of the isolates demonstrated high-level resistance to cotrimoxazole. The most prevalent serogroups or serotypes of antibiotic-resistant isolates were 14, 19F, 19A, 6A, 6B, and 4. No risk factors for antibiotic resistance were identified. Haemophilus influenzae type b was isolated from 8% of the children in Gaborone and from 3% of the children in Francistown. Almost a third of the isolates were resistant to ampicillin.

CONCLUSIONS

The high levels of antibiotic resistance in pneumococci isolated from children in Botswana suggest that the clinical management of meningitis and otitis media with a b-lactam antibiotic may fail in a significant proportion of cases and that empiric first-line use of cefotaxime or ceftriaxone for meningitis and higher dose amoxicillin (90 mg/kg/day) for otitis media is recommended. The levels of penicillin resistance in this study would not impact on the management of pneumonia with amoxicillin.

Nasopharyngeal carriage of community-acquired, antibiotic-resistant Streptococcus pneumoniae in a Zambian paediatric population

The emergence of antibiotic-resistant Streptococcus pneumoniae is an international health problem. Apart from South Africa few data on pneumococcal resistance are available for sub-Saharan Africa. This study examines the nasopharyngeal carriage and prevalence of antibiotic resistance in pneumococci isolated from 260 Zambian children aged < 6 years. Pneumococci were isolated from 71.9% of the children; the odds of carrying organisms were twice as high among children < 2 years of age compared with older children. Antibacterial resistance was found in 34.1% of the isolates; resistance to tetracycline, penicillin, sulfamethoxazole + trimethoprim, and chloramphenicol occurred in 23.0%, 14.3%, 12.7%, and 3.9% of the isolates, respectively. Only 4% of the isolates were resistant to three drugs. High-level resistance was found in all isolates resistant to tetracycline; but only intermediate level penicillin resistance was found. A total of 11.1% of the isolates demonstrated intermediate resistance to sulfamethoxazole + trimethoprim. Children aged < 6 months were less likely to carry antibiotic-resistant organisms. Antibiotic resistance in S. pneumoniae appears to be an emerging public health problem in Zambia, and the national policy for the empirical treatment of pneumococcal meningitis and acute respiratory tract infections may need to be re-evaluated. The establishment of ongoing surveillance to monitor trends in pneumococcal resistance should be considered.

Invasive candidiasis in the ICU--pathogenesis and management strategy

How should new and old antifungals be used in the management of invasive candidiasis in ICU patients? A pathogenesis-based management strategy for invasive candidiasis is outlined. Colonisation of the catheterised bladder by Candida species should be eliminated to prevent invasion from the urinary tract. Invasion from the peritoneum (in the patient with a perforated bowel) should be treated promptly to prevent local vascular invasion. Empirical therapy is recommended for treatment of suspected disseminated candidiasis, 'pulmonary' candidiasis and vascular-access candidiasis. Dose and duration of therapy are decided according to clinically determined patient/disease categories and modified according to information from laboratory results. Short-term low-dose regimens are suitable for peritoneal candidiasis that is recognised early, and for vascular-access candidiasis, provided the source-catheter can be removed.

Increasing prevalence of penicillin-resistant pneumococcal infections in children in southern Israel: implications for future immunization policies

Although penicillin-resistant pneumococci (PR-PnC) are recognized as an increasing problem worldwide, data on the prevalence of these strains among pediatric patients are incomplete. The present study was conducted in southern Israel (1) to investigate the frequency of PR-PnC in invasive and middle ear infections in pediatric patients and (2) to assess the impact of resistance on the potential role of the candidate conjugate vaccines in preventing childhood PR-PnC infections. A total of 120 blood or cerebrospinal fluid isolates from 1987 to 1993 and 78 ear isolates from 1992 to 1993 were serogrouped and tested for susceptibility to antibacterial agents. The prevalence of PR-PnC among invasive isolates increased from 16% in the years 1987 to 1991 to 36% in 1992 to 1993 (P = 0.019). This increase was noted mainly for intermediately resistant strains (minimal inhibitory concentration, 0.12 to 1.0 micrograms/ml) whereas the prevalence of highly resistant strains was 3 and 2% for the 2 periods, respectively. The prevalence of PR-PnC among ear isolates in 1992 to 1993 was 42%. Resistance to other antimicrobial agents (one or more of the following: tetracycline, erythromycin, clindamycin and chloramphenicol) was found in 16 (8%) isolates, and multiple resistance (resistance to > or = 3 antibacterial agents) was found in 9 (5%) isolates. Sixty-five (99%) of the 66 resistant isolates belong to Serogroups 6, 14, 19 and 23. The prevalence of these 4 serogroups rose from 37% in 1987 to 1991 to 66% in 1992 to 1993 (P = 0.043). This rise was mainly because of Serogroup 23, the prevalence of which rose from 3% in 1987 to 1991 to 23% in 1992 to 1993 (P < 0.001). Eighty-five percent of all isolates belonging to Serogroup 23 were resistant to penicillin. Because Serogroups 6, 14, 19 and 23 are among the commonest pediatric pneumococcal strains, the newly developed conjugate pneumococcal vaccines contain these 4 serogroups. The selection of antibiotic-resistant strains has thus led to a change in the spectrum of serotypes causing invasive disease and to a situation of potential increase in vaccine coverage for the proposed pneumococcal conjugate vaccines.

Antimicrobial resistance in Streptococcus pneumoniae: a South African perspective

Resistance to penicillin among South African strains of Streptococcus pneumoniae increased from 4.9% in 1979 to 14.4% in 1990. Except for resistance to co-trimoxazole (44%), resistance to other antimicrobial agents remained relatively low. Multiply resistant strains belonged mainly to serovars 6B, 19A, 14, and, more recently, 23F. Use of chloramphenicol to treat meningitis caused by strains relatively resistant to penicillin proved to be unsatisfactory, probably because of the inadequate bactericidal activity of chloramphenicol against these strains. Spread of penicillin-resistant nasopharyngeal strains in pediatric wards was most common among children who received antimicrobial therapy. Penicillin-binding protein (PBP) patterns were shown to vary in resistant clinical strains. Interspecies transfer of penicillin resistance between Streptococcus mitis and S. pneumoniae was demonstrated and antigenic homology was found in PBPs 1A and 2B of strains belonging to these species. Restriction enzyme mapping following DNA amplification of the PBP 2B gene revealed six arrangements among South African strains within serogroup 19. Despite extensive studies in South Africa and several other countries, many questions with regard to the global problem of antimicrobial resistance among S. pneumoniae strains remain unanswered, especially those that relate to prevalence in developing regions of the world.

Evidence for an indirect cholinergic regulation of blood flow in the hypothalamus of conscious rabbits

1 The effects of methacholine, atropine and adrenoceptor blockade on hypothalamic blood flow (HBF) were measured in conscious rabbits. 2 A dose of 1 microgram methacholine increased HBF while smaller and larger doses had no significant effect. 3 The vasodilatation induced by methacholine was blocked by atropine and by chemical sympathectomy of the hypothalamus with 6-hydroxydopamine. 4 The vasodilatation was reversed by propranolol but was not affected by phenoxybenzamine. 5 These results suggest that the vasodilator action of muscarinic receptor agonists on hypothalamic resistance vessels depends upon the integrity of a noradrenergic system, and is mediated via beta-adrenoceptors.