Nasopharyngeal colonization with Streptococcus pneumoniae in children receiving trimethoprim-sulfamethoxazole prophylaxis

Does cotrimoxazole prophylaxis in HIV patients increase the drug resistance of pneumococci? A comparative cross-sectional study in southern Ethiopia

BACKGROUND

Infections caused by antibiotic-resistant bacteria results in high rates of morbidity and mortality. Although the prolonged cotrimoxazole (CTX) prophylaxis is arguably associated with the risk of increasing drug resistance in the common pathogens, information regarding its impact on Streptococci pneumoniae / pneumococcus is very limited.

OBJECTIVE

This study was conducted to investigate the effect of cotrimoxazole prophylaxis on nasopharyngeal colonization rate and antimicrobial resistance using Streptococci pneumoniae (pneumococcus) as an indicator organism among HIV patients in Arba Minch, Ethiopia.

MATERIALS AND METHODS

A comparative cross-sectional study was designed and conducted among HIV patients attending the Anti-Retroviral Treatment (ART) clinic of Arba Minch General Hospital (AMGH) from April 01 to August 31, 2018. A total of 252 participants were systematically selected and clustered into two study groups based on their CTX prophylaxis status, one taking CTX prophylaxis, and the second one, the control group (without prophylaxis). A structured questionnaire was used to collect socio-demographic and clinical data from patients. A nasopharyngeal swab was collected and cultured for pneumococcal isolation and identification in accordance with standard microbiological techniques. An antibiotics sensitivity test was performed according to the CLSI guidelines. Data were analyzed using the Statistical package for social science (SPSS) version 20. The primary outcome was determined using logistic regression analysis.

RESULTS

Of the 252 enrolled HIV patients (mean age (37.38± 9.03 years), 144 (57.14%) were males. The overall, nasopharyngeal colonization rate of S. pneumoniae was 13.5% (95% CI: 8.4-15.6). Asymptomatic pneumococcal carriage rates among patients on CTX prophylaxis and the control group were 16.3%, and 10.3% respectively (p-value = 0.03). Regarding the risk factors analyzed, CTX prophylaxis (AOR: 2.2; 95% CI: 1.05-4.9) and gender (AOR: 2.5; 95% CI: 1.09-5.93) were significantly associated with pneumococcal colonization, showing a male preponderance. Cotrimoxazole-resistant pneumococci were 85.7% vs. 47.4% in the prophylaxis group and the control group respectively and it was statistically significant (AOR: 6.7; 95% CI: 1.3-36). Percentages of multi-drug resistant isolates in these two groups were 38.09 and 15.38 respectively (p-value = 0.04). Among the CTX resistant pneumococci isolates, 85% were also found to be co-resistant towards penicillin and was statistically significant.

CONCLUSION

The percentage prevalence of nasopharyngeal pneumococci colonization was higher in patients taking CTX prophylaxis. It was noted that CTX prophylaxis eventually results in the selection of cotrimoxazole resistance and multi-drug resistance in pneumococci. There is evidence of existing cross-resistance between cotrimoxazole and penicillin antibiotics. Therefore, CTX prophylaxis must be administered judiciously. Surveillance for antimicrobial susceptibility is warranted where the prophylaxis is common.

Impact of cotrimoxazole on carriage and antibiotic resistance of Streptococcus pneumoniae and Haemophilus influenzae in HIV-infected children in Zambia

This is a substudy of a larger randomized controlled trial on HIV-infected Zambian children, which revealed that cotrimoxazole prophylaxis reduced morbidity and mortality despite a background of high cotrimoxazole resistance. The impact of cotrimoxazole on the carriage and antibiotic resistance of Streptococcus pneumoniae and Haemophilus influenzae as major causes of childhood mortality in HIV-infected children was investigated since these are unclear. Representative nasopharyngeal swabs were taken prior to randomization for 181 of 534 children (92 on cotrimoxazole and 89 on placebo). Bacterial identification and antibiotic susceptibility were performed by routine methods. Due to reduced mortality, prophylactic cotrimoxazole increased the median time from randomization to the last specimen from 48 to 56 months (P = 0.001). The carriage of H. influenzae was unaltered by cotrimoxazole. Carriage of S. pneumoniae increased slightly in both arms but was not statistically significant in the placebo arm. In S. pneumoniae switching between carriage and no carriage in consecutive pairs of samples was unaffected by cotrimoxazole (P = 0.18) with a suggestion that the probability of remaining carriage free was lower (P = 0.10). In H. influenzae cotrimoxazole decreased switching from carriage to no carriage (P = 0.02). Cotrimoxazole resistance levels were higher in postbaseline samples in the cotrimoxazole arm than in the placebo arm (S. pneumoniae, P < 0.0001; H. influenzae, P = 0.005). Cotrimoxazole decreased switching from cotrimoxazole resistance to cotrimoxazole sensitivity in S. pneumoniae (P = 0.002) and reduced the chance of H. influenzae remaining cotrimoxazole sensitive (P = 0.05). No associations were observed between the percentage of CD4 (CD4%), the change in CD4% from baseline, child age at date of specimen, child gender, or sampling month with carriage of either pathogen.

Nasopharyngeal carriage of Streptococcus pneumoniae in Navajo and White Mountain Apache children before the introduction of pneumococcal conjugate vaccine

BACKGROUND

Infants and children are frequently colonized with pneumococcus. Recent nasopharyngeal acquisition of pneumococcus is thought to precede disease episodes. The increased risk of pneumococcal disease among Navajo and White Mountain Apache populations has been documented. Little is known about the dynamics of pneumococcal carriage in these populations.

METHODS

A group randomized, controlled trial of 7-valent conjugate pneumococcal vaccine (PnCRM7, Wyeth) was conducted on the Navajo and Apache reservations. A nasopharyngeal (NP) carriage study was nested in the trial to evaluate the impact of PnCRM7 on carriage. Children <6 years of age had NP swabs collected at enrollment and at 6 and 12 months following enrollment. We analyzed carriage data from children in control vaccine randomized communities to describe the epidemiology of pneumococcal carriage.

RESULTS

Of the 410 participants enrolled, 92% were colonized with pneumococcus at least once during the course of the study. Sixty-three percent of NP specimens were positive for pneumococcus. The most common serotypes were 6A, 6B, nontypable, 23F, 14, 19F, 19A, and 9V. Thirty-eight percent of isolates were vaccine serotypes. Age <2 years, male sex, daycare attendance, and having a sibling colonized with pneumococcus were associated with an increased risk of carriage.

CONCLUSIONS

The high carriage prevalence among Navajo and Apache children reflects an intense exposure to pneumococcus. The lack of modifiable risk factors for carriage highlights the importance of preventive strategies for disease control.

Effect of presumptive co-trimoxazole prophylaxis on pneumococcal colonization rates, seroepidemiology and antibiotic resistance in Zambian infants: a longitudinal cohort study

OBJECTIVE

To ascertain the microbiological consequences of WHO's recommendation for presumptive co-trimoxazole prophylaxis for infants with perinatal HIV exposure.

METHODS

Using a longitudinal cohort design, we followed HIV-exposed and HIV-unexposed infants trimonthly for up to 18 months per infant. HIV-exposed infants received daily co-trimoxazole prophylaxis from 6 weeks to > or = 12 months of age. Using Streptococcus pneumoniae as our sentinel pathogen, we measured how co-trimoxazole altered nasopharyngeal colonization, pneumococcal resistance to antibiotics and serotype distribution as a function of co-trimoxazole exposure.

FINDINGS

From 260 infants followed for 3096 patient-months, we detected pneumococci in 360/1394 (25.8%) samples. HIV-exposed infants were colonized more frequently than HIV-unexposed infants (risk ratio, RR: 1.4; 95% confidence interval, CI: 1.0-1.9, P = 0.04). Co-trimoxazole prophylaxis reduced colonization by ca 7% but increased the risk of colonization with co-trimoxazole-resistant pneumococci within 6 weeks of starting prophylaxis (RR: 3.2; 95% CI: 1.3-7.8, P = 0.04). Prophylaxis with co-trimoxazole led to a small but statistically significant increase of nasopharyngeal colonization with pneumococci not susceptible to clindamycin (RR: 1.6; 95% CI: 1.0-2.6, P = 0.04) but did not increase the risk of non-susceptibility to penicillin (RR: 1.1; 95% CI: 0.7-1.7), erythromycin (RR: 1.0; 95% CI: 0.6-1.7), tetracycline (RR: 0.9; 95% CI: 0.6-1.5) or chloramphenicol (RR: 0.8; 95% CI: 0.3-2.3). Co-trimoxazole prophylaxis did not cause the prevailing pneumococcal serotypes to differ from those that are targeted by the 7-valent conjugate pneumococcal vaccine (RR: 1.0; 95% CI: 0.7-1.6).

CONCLUSION

Co-trimoxazole prophylaxis modestly suppresses pneumococcal colonization but accelerates infant acquisition of co-trimoxazole- and clindamycin-resistant pneumococci. Co-trimoxazole prophylaxis appears unlikely to compromise the future efficacy of conjugate vaccines.

Invasive pneumococcal disease among human immunodeficiency virus-infected children, 1989-2006

OBJECTIVE

The heptavalent pneumococcal conjugate vaccine (PCV7) has decreased the incidence of pediatric invasive pneumococcal disease (IPD) in the United States. Few data exist on the changing IPD incidence in HIV-infected children.

METHODS

Diagnostic codes and clinical microbiology laboratory records identified cases of IPD from 1989 to 2006 in perinatally-infected children <18 years of age followed at an urban HIV clinic. IPD incidence was calculated and serotype distribution and antibiotic resistance were recorded.

RESULTS

Two-hundred fifty-six patients were followed for 1756 person-years (PY). The sample was 59% female, 76% black, 14% white, and 8% Hispanic. Of 21 episodes of IPD (1200/100,000 PY), 17 (81%) were female. IPD cases had a median age of 6.3 years (interquartile range [IQR]: 2.3-9.9 years), median CD4% of 17% (IQR: 11-28%), and median CD4 count of 415 cells/mm (range, 2-1699 cells/mm). Bacteremia was the commonest form of IPD (19 episodes; 1080/100,000 PY). After HAART introduction in 1996, the incidence of IPD decreased 84% from 1862/100,000 PY in 1989-1995 to 292/100,000 PY in 1997-1999 (incidence rate ratio [IRR]: 0.16, P = 0.03). After PCV7 introduction in 2000, IPD incidence showed a nonsignificant increase from 292 of 100,000 PY in 1997-1999 to 860 of 100,000 PY in 2001-2006 (IRR: 2.94; P = 0.16). The percentages of IPD isolates nonsusceptible to penicillin and trimethoprim-sulfamethoxazole were 19% and 33%, respectively. Vaccine serotypes accounted for 38% of isolates, vaccine-related 14%, nonvaccine 33%, and the serotype was unknown in 14%.

CONCLUSIONS

The incidence of IPD among perinatally HIV-infected children decreased after the introduction of HAART. Ongoing monitoring is required to determine the effect of PCV7 on IPD in this vulnerable population.

High incidence of antimicrobial resistant organisms including extended spectrum beta-lactamase producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus in nasopharyngeal and blood isolates of HIV-infected children from Cape Town, South Africa

Background

There is little information on nasopharyngeal (NP) flora or bacteremia in HIV-infected children. Our aim was to describe the organisms and antimicrobial resistance patterns in children enrolled in a prospective study comparing daily and three times weekly trimethoprim-sulfamethoxazole (TMP-SMX) and isoniazid (INH) or placebo prophylaxis.

Methods

NP swabs were taken at baseline from HIV-infected children enrolled in the study. Standard microbiological techniques were used. Children were grouped according to previous or current exposure to TMP-SMX and whether enrolled to the study during a period of hospitalization. Blood culture results were also recorded within 12 months of baseline.

Results

Two hundred and three children, median age 1.8 (Interquartile [IQ]: 0.7–4) years had NP swabs submitted for culture. One hundred and eighty-four (90.7%) had either stage B or C HIV disease. One hundred and forty-one (69.8%) were receiving TMP-SMX and 19 (9.4%) were on antiretroviral therapy. The majority, 168 (82%) had a history of hospitalization and 91 (44.8%) were enrolled during a period of hospitalization. Thirty-two subjects (16.2%) died within 12 months of study entry.

One hundred and eighty-one potential pathogens were found in 167 children. The most commonly isolated organisms were Streptococcus pneumoniae (48: 22.2%), Gram-negative respiratory organisms (Haemophilus influenzae and Moraxella catarrhalis) (47: 21.8%), Staphylococcus aureus (44: 20.4%), Enterobacteriaceae 32 (14.8%) and Pseudomonas 5 (2.3%).

Resistance to TMP-SMX occurred in > 80% of pathogens except for M. catarrhalis (2: 18.2% of tested organisms). TMP-SMX resistance tended to be higher in those receiving it at baseline (p = 0.065). Carriage of Methicillin resistant S. aureus (MRSA) was significantly associated with being on TMP-SMX at baseline (p = 0.002). Minimal inhibitory concentrations (MIC) to penicillin were determined for 18 S. pneumoniae isolates: 7 (38.9%) were fully sensitive (MIC ≤ 0.06 μg/ml), 9 (50%) had intermediate resistance (MIC 0.12 – 1 μg/ml) and 2 (11.1%) had high level resistance (MIC ≥2 μg/ml). Fifty percent of Enterobacteriaceae produced extended spectrum beta-lactamases (ESBL) (resistant to third generation cephalosporins) and 56% were resistant to gentamicin. Seventy-seven percent of S. aureus were MRSA. Carriage of resistant organisms was not associated with hospitalization.

On multivariate logistic regression, risk factors for colonization with Enterobacteriaceae were age ≤ one year (Odds ratio 4.4; 95% Confidence Interval 1.9–10.9; p = 0.0008) and CDC stage C disease (Odds ratio 3.6; 95% Confidence Interval 1.5–8.6; p = 0.005)

Nineteen (9.4%) subjects had 23 episodes of bacteremia. Enterobacteriaceae were most commonly isolated (13 of 25 isolates), of which 6 (46%) produced ESBL and were resistant to gentamicin.

Conclusion

HIV-infected children are colonized with potential pathogens, most of which are resistant to commonly used antibiotics. TMP-SMX resistance is extremely common. Antibiotic resistance is widespread in colonizing organisms and those causing invasive disease. Antibiotic recommendations should take cognizance of resistance patterns. Antibiotics appropriate for ESBL-producing Enterobacteriaceae and MRSA should be used for severely ill HIV-infected children in our region. Further study of antibiotic resistance patterns in HIV-infected children from other areas is needed.

Scaling-up co-trimoxazole prophylaxis in HIV-exposed and HIV-infected children in high HIV-prevalence countries

Co-trimoxazole (trimethoprim-sulfamethoxazole) is a widely available antibiotic that substantially reduces HIV-related morbidity and mortality in both adults and children. Prophylaxis with co-trimoxazole is a recommended intervention of proven benefit that could serve not only as an initial step towards improving paediatric care in young children with limited access to antiretroviral treatment, but also as an important complement to antiretroviral therapy in resource-limited settings. Despite co-trimoxazole's known clinical benefits, the potential operational benefits, and favourable recommendations by WHO, UNAIDS, and UNICEF, its routine use in developing countries--particularly sub-Saharan Africa--has remained limited. Out of an estimated 4 million children in need of co-trimoxazole prophylaxis (HIV-exposed and HIV-infected), only 4% are currently receiving this intervention. We discuss some of the major barriers preventing the scale-up of co-trimoxazole prophylaxis for children in countries with a high prevalence of HIV and propose specific actions required to tackle these challenges.

HIV and pneumococcal disease

PURPOSE OF REVIEW

To describe the impact of highly active antiretroviral therapy on the burden of pneumococcal disease and advances in our understanding of the impact of HIV on this disease.

RECENT FINDINGS

Although highly active antiretroviral therapy has reduced the burden of pneumococcal disease among HIV-infected adults, these infections remain far more common than in HIV uninfected adults. HIV-infected adults who smoke or have comorbidities are at particular risk. In the absence of highly active antiretroviral therapy, pneumococcal meningitis has emerged in Africa as a major disease burden with a high mortality among HIV-infected children and adults. Conjugate pneumococcal vaccine protects HIV-infected infants from pneumococcal pneumonia. In the United States, where conjugate vaccine is given to children, herd immunity has reduced the burden of invasive pneumococcal disease among HIV-infected adults.

SUMMARY

The pneumococcus remains a significant cause of morbidity and mortality among HIV-infected children and adults, both in developed and in developing countries.

Care and treatment of HIV-infected children in Africa: issues and challenges at the district hospital level

More than 90% of pediatric HIV infection occurs in sub-Saharan Africa and 75% of these children currently die before their fifth birthday. Most HIV-infected children in Africa rely on district hospitals for HIV treatment, but insufficient attention has been paid to improving HIV/AIDS care at this level. Considerable confusion exists about optimal use of combination antiretroviral treatment, prophylaxis for opportunistic infections and other rational healthcare interventions that can greatly improve the quality of life for these children. A simple and inexpensive infant HIV diagnostic assay and alternative laboratory markers of pediatric HIV disease progression would be highly beneficial. Routine anthropometric and neurodevelopmental assessments could help guide initiation and monitoring of antiretroviral therapy. Even in the absence of antiretroviral therapy, interventions such as immunizations, provision of micronutrients and nutrition counseling, prevention and treatment of opportunistic as well as endemic infections (such as helminths and malaria) can substantially reduce pediatric HIV-related morbidity and mortality. The need for pain relief, palliative care, counseling and emotional support is often underestimated. Surmounting the sense of hopelessness by providing district healthcare workers with training in basic pediatric HIV/AIDS care is an urgent priority.

Antibiotic resistance of urinary tract pathogens and evaluation of empirical treatment in Turkish children with urinary tract infections

The changing pattern of antimicrobial resistance in the causative microorganisms of urinary tract infection (UTI) in childhood is a growing problem. The aims of this study were to assess the resistance patterns of urinary isolates to commonly used antimicrobials and to evaluate the options for empirical treatment of UTI. A prospective cross-sectional analysis of bacteria isolated from children with UTI was performed between January 2003 and January 2004. Resistance to antibiotics was analysed in three age groups: Group I, < or =12 months; Group II, 13-60 months; and Group III, >60 months. A total of 165 urinary pathogens were isolated from 131 patients. Mean patient age was 63.7+/-49.8 months. The most common causative agent was Escherichia coli (87% of cases) followed by Klebsiella pneumoniae (10%). Resistance to ampicillin (74.2%) and co-trimoxazole (61.3%) was significant in all isolates. Nitrofurantoin was the most active agent against E. coli (2.2% resistant isolates), followed by amikacin (4.9%), ceftriaxone (7.5%) and ciprofloxacin (12%). None of the isolates from Group I patients were resistant to ciprofloxacin and a low resistance rate (7.1%) was noted for amikacin. In Group II patients, none of the isolates were resistant to amikacin, and ceftriaxone was the second most suitable antibiotic (resistance rate 2.2%). In Group III patients, the lowest resistance rate was against nitrofurantoin (2.7%). In conclusion, we observed that the use of ampicillin and co-trimoxazole as a single agent for empirical treatment of a suspected UTI would not cover the majority of urinary pathogens in our region. Whilst amikacin, with a negligible resistance rate, was suitable in all age groups, gentamicin might still be useful as an empirical treatment of UTI in children aged >1 year. Nitrofurantoin could be included as a reasonable alternative in the empirical treatment of lower UTI in older children.

Clinical impact and cost-effectiveness of co-trimoxazole prophylaxis in patients with HIV/AIDS in Côte d'Ivoire: a trial-based analysis

BACKGROUND

In 2000, WHO/UNAIDS recommended co-trimoxazole prophylaxis for persons at early stages of HIV infection (WHO stage > or = 2) in sub-Saharan Africa.

OBJECTIVE

To assess the cost-effectiveness of alternative strategies for initiation of co-trimoxazole in Côte d'Ivoire.

DESIGN

Cost-effectiveness analysis with an HIV simulation model using clinical and cost data from a randomized trial of co-trimoxazole in HIV-infected adults.

METHODS

The study included HIV-infected patients in Côte d'Ivoire, with median age 33 years. Thirty-four percent were classified as WHO stage 2, 59% as stage 3, and 7% as stage 4. The mean CD4 cell count was 331 x 10(6) cells/l. The interventions were no prophylaxis, clinical criteria-based co-trimoxazole initiation (early: WHO stage > or = 2; late: WHO stage > or = 3), CD4-based co-trimoxazole initiation (< 500, < 200, < 50 x 10(6) CD4 cells/l). The outcome measures were life expectancy, lifetime costs, and incremental cost-effectiveness.

RESULTS

The most effective strategy, initiation of co-trimoxazole prophylaxis at WHO stage > or = 2, increased undiscounted life expectancy by 5.2 months, discounted life expectancy by 4.4 months, and lifetime costs by US dollars 60, compared with no prophylaxis. Delaying prophylaxis initiation until WHO stage >or = 3 was less costly and less effective. All CD4-based strategies were dominated. The incremental cost-effectiveness of early versus late co-trimoxazole prophylaxis initiation was US dollars 200/year of life gained. Results were stable despite wide variations in plausible assumptions about bacterial resistance and the prophylaxis efficacy on co-trimoxazole-resistant strains.

CONCLUSIONS

For HIV-infected adults in Côte d'Ivoire, co-trimoxazole prophylaxis is reasonably cost-effective and most effective if initiated when WHO stage > or = 2. Early co-trimoxazole prophylaxis will prevent complications prior to antiretroviral therapy initiation and should be considered an essential component of care for early HIV in sub-Saharan Africa.

Meta-analysis of bacterial resistance to macrolides

OBJECTIVES

Understanding changing resistance patterns is important in determining appropriate antibiotic treatments. This meta-analysis systematically evaluated resistance of Streptococcus pneumoniae and Streptococcus pyogenes to macrolide antibiotics among patients with community-acquired respiratory tract infections.

METHODS

MEDLINE and EMBASE databases were searched and experts were consulted to identify published and unpublished literature reporting macrolide resistance rates. Identified studies were evaluated by two independent reviewers; those meeting a priori specified criteria (resistance by patient condition and strain, resistance thresholds, 1997-2003 isolates) were included. Data from included studies were abstracted by two independent reviewers using a standard review form. Discrepancies in abstracted data were resolved by the study investigator.

RESULTS

Random-effects meta-analysis was performed for outcomes present in at least four studies overall and for specified subgroups. We identified 3849 studies and performed detailed review on 407; of these 29, published between 1998-2003, met the inclusion criteria. Mean resistance of S. pneumoniae isolates to azithromycin was 27.2% [95% confidence interval (CI) 24.6-29.7]; mean resistance to erythromycin was statistically equivalent (30.4%; 95% CI 28.1-32.7). Resistance of S. pyogenes to erythromycin (30.0%; CI 18.6-41.5) was similar to that of S. pneumoniae. Too few studies of clarithromycin were included to allow evaluation of resistance. In subgroup analyses, substantial variation in resistance to erythromycin was seen by geographic area.

CONCLUSIONS

Reported macrolide resistance of S. pneumoniae varies substantially and may be a significant issue in certain regions. Use of meta-analysis to aggregate individual studies enabled determination of robust values for macrolide resistance. This information is useful for clinical and policy decision makers in developing appropriate antibiotic strategies.

Effectiveness of cotrimoxazole prophylaxis on mortality in adults with tuberculosis in rural South Africa

BACKGROUND

Adults with dual tuberculosis (TB) and HIV infection have a poor outcome. Studies in West Africa suggest that cotrimoxazole prophylaxis may reduce this mortality.

OBJECTIVE

To evaluate the effectiveness of cotrimoxazole in reducing mortality in adults with active TB, irrespective of HIV status, in a high prevalence setting.

DESIGN

Cohort study using historical controls.

METHODS

Adults treated for TB between 1998 and 2000 were traced and vital status at 6 months ascertained (2004: control group). All adults starting treatment for TB between June 2001 and June 2002 were offered cotrimoxazole prophylaxis 960 mg once daily for 6 months during TB treatment irrespective of HIV status (1321: intervention group). Mortality, adverse reactions and adherence were compared between intervention and control groups.

RESULTS

HIV seroprevalence in patients with TB at the start of the intervention was estimated to be 78%. Mortality at 6 months was 29% lower in the group given cotrimoxazole than in the control group. The number needed to treat to prevent one death during the period of TB treatment was 24. The benefit was seen across all types of TB but was only evident in new patients; patients being retreated had similar outcomes in both groups. Adverse events were infrequent and minor, with only two participants having treatment stopped for this reason.

CONCLUSION

Cotrimoxazole prophylaxis for all adults with TB, irrespective of HIV status, in an area of high HIV seroprevalence may be a feasible, safe and effective way to reduce mortality for the duration of treatment.

Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolated from the nasopharynges of asymptomatic children and molecular analysis of S. pneumoniae and H. influenzae strain replacement in the nasopharynx

Nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in 226 children in different settings (in a crèche [day care center], in an orphanage, and at home) during two seasons (winter and spring) was studied. The rates of carriage of S. pneumoniae and H. influenzae were markedly higher in the crèche and in the orphanage than in the home setting (e.g., 56.5, 63.3, and 25.9%, respectively, for S. pneumoniae in winter). Approximately 80% of the S. pneumoniae isolates identified in the crèche and in the orphanage belonged to the serotypes represented in the seven-valent pneumococcal vaccine, and 4.4% of the children were colonized by H. influenzae type b. Almost all H. influenzae isolates were fully susceptible to the antimicrobial agents tested, and only five (3.6%) produced beta-lactamase; in contrast, 100% of the M. catarrhalis isolates were beta-lactamase positive. Among S. pneumoniae isolates, 36.2% were nonsusceptible to penicillin (PNSP) and 11.8% were fully resistant to penicillin (PRP). All PNSP isolates were obtained from children at the crèche and at the orphanage but not among children brought up at home, and all PRP isolates showed a multiresistant phenotype. Colonization by PRP isolates correlated well with prior treatment with beta-lactams. For the majority of children colonized at both sampling times, strain replacement of S. pneumoniae and H. influenzae was observed; long-term colonization by a single strain was rare.

Risk factors for the nasopharyngeal carriage of respiratory pathogens by Portuguese children: phenotype and antimicrobial susceptibility of Haemophilus influenzae and Streptococcus pneumoniae

Between 1997 and 2000 nasopharyngeal specimens were obtained from 466 children < or = 12 years old attending the Pediatric Emergency Department at S. Francisco Xavier Hospital, Lisbon, to evaluate risk factors for nasopharyngeal carriage of Haemophilus influenzae and Streptococcus pneumoniae and to characterize their phenotype and antimicrobial susceptibility. The attending pediatrician completed written questionnaires about the children's demographic and clinical histories. Over half the children (52.8%) carried H. influenzae and/or S. pneumoniae. Forty-one percent of these children had H. influenzae, 22.8% had S. pneumoniae and 36.2% had both. Risk factors identified for carriage of respiratory pathogens were: age below 3 years (p < 0.05), black race (p < 0.01), attending a daycare center (p < 0.05), and having a lower respiratory infection (p < 0.05). Asthmatic children were less likely to be carriers (p = 0.004). About two-thirds of H. influenzae isolates were susceptible to all antibiotics tested, 7.9% were beta-lactamase producers, 16.4% were nonsusceptible to trimethoprim, and 6.9% were intermediately resistant to clarithromycin. Over half (57.1%) of S. pneumoniae isolates were susceptible to all antibiotics tested, 21.1% were multiresistant, 23.3% were nonsusceptible to penicillin, and about 20% were resistant to macrolides. Low-level resistance to third-generation cephalosporins was detected in 2.3%. The data reflect the controversy surrounding risk factors of nasopharyngeal colonization. These may have significant implications on clinical practice and on antimicrobial strategies to prevent the appearance of further resistant strains. Our findings highlight the importance to investigate the relationship between asthma and carriage.

Serotypes of respiratory tract isolates of Streptococcus pneumoniae from Jamaican children

BACKGROUND

Data are lacking on the pneumococcal serotypes present in many developing regions, including the Caribbean. We examined the serotypes of nasopharyngeal (NP) isolates of pneumococci obtained from Jamaican children.

METHODS

We obtained NP samples from children seen in the Emergency Department at the Bustamante Children's Hospital. The samples were transported to Canada for isolation and serotyping of pneumococci.

RESULTS

We obtained 94 isolates from 276 children; median age 3.4 years. The majority (57%) had symptoms of acute respiratory infection at the time of sampling. The main serotypes carried were 6B (20.5%), 19F (14.5%), and 14 (8.4%). Non-typable isolates accounted for 10.8% of the isolates. Fifty-nine per cent of the serotypes were present among the 11 being considered for candidate pneumococcal conjugate vaccines (95% CI 48-70%); the corresponding proportion present in the recently licensed 7-valent vaccine was 57% (95% CI 45-67%). A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines (P<0.0001; reference=85% expected serotype representation). Less than 5% of isolates were non-susceptible to penicillin (3.2%), cefotaxime-ceftriaxone (3.2%) and cefuroxime (3.2%), while 8.4% and 1.l% of isolates were resistant to trimethoprim-sulfamethoxazole and erythromycin respectively. There were three isolates with resistance to two or more classes of drug. These isolates were all resistant to penicillin (MIC 2 micro g/mL); the serotypes were 14, 23F, and 19F.

CONCLUSION

A significant proportion of the serotypes found is absent from those to be included in future conjugate vaccines.

Cotrimoxazole prophylaxis in adults infected with HIV in low-income countries

Two recent placebo-controlled trials of cotrimoxazole in HIV-infected adults, conducted by independent groups but in the same city (Abidjan, Côte d'Ivoire), have both shown important positive impacts. One study where cotrimoxazole or placebo was given to tuberculosis-HIV co-infected patients showed a significant reduction in mortality; the second study with a similar protocol, in HIV-infected patients without major co-morbidity at trial entry, showed a significant reduction in morbidity but no effect on mortality. These data have been interpreted by some as conclusive enough to recommend cotrimoxazole for all people with HIV/AIDS in Africa. Others have been more cautious, noting that Abidjan has an atypically low rate of cotrimoxazole resistance among bacterial pathogens, and consider more data are needed before such a sweeping policy decision can be made. Recent data from Senegal showed no benefit but this trial, like several others, was terminated prematurely because the investigators felt it unethical to continue after the Abidjan results were released. The situation is somewhat confused and confusing. This review attempts to put the current debate into context and to review the current position of cotrimoxazole in relation to other primary prophylaxis strategies in Africa.

Bacteriologic and clinical efficacy of trimethoprim-sulfamethoxazole for treatment of acute otitis media

BACKGROUND

Trimethoprim-sulfamethoxazole (T/S) has often been used as first and second line of treatment for acute otitis media (AOM). Because of the increasing resistance of Streptococcus pneumoniae and Haemophilus influenzae to T/S, we undertook the present study to investigate the bacteriologic and clinical efficacy of this drug in AOM.

METHODS

Fifty-four culture-positive evaluable patients ages 3 to 32 months with AOM were treated with T/S 4/20 mg/kg in two divided daily doses for 10 days. Middle ear fluid (MEF) was cultured at enrollment (Day 1) and on Days 4 and 5 after initiation of treatment. Additional MEF cultures were obtained if clinical relapse occurred. Clinical failure was determined when the symptoms and signs of AOM did not improve or recurred during therapy. Bacteriologic failure was defined by positive culture on Days 4 and 5, or negative on Days 4 and 5 but positive again before the end of treatment. Patients were followed until Day 28 +/- 2.

RESULTS

A total of 67 organisms were isolated from MEF specimens of the 54 study patients: S. pneumoniae, 24; H. influenzae, 40; and Streptococcus pyogenes, 3. Fifteen (63%) of 24 S. pneumoniae were nonsusceptible to T/S (trimethoprim MIC, >0.5 microg/ml), of which 10 (67%) were highly resistant to T/S (trimethoprim MIC, > or = 4.0 microg/ml). Twelve (30%) of 40 H. influenzae and all 3 S. pyogenes isolates were nonsusceptible to T/S (MIC > or = 4.0 microg/ml). Bacteriologic eradication occurred in 9 of 9 (100%) and 27 of 27 (100%) T/S-susceptible S. pneumoniae and H. influenzae, respectively, vs. 4 of 15 (27%) and 6 of 12 (50%) T/S-nonsusceptible S. pneumoniae and H. influenzae, respectively (P < 0.001). The 3 patients with S. pyogenes failed bacteriologically. Nine new organisms, not initially isolated, emerged during treatment, 7 of which (77%) were resistant to T/S. Altogether bacteriologic failure (organisms not eradicated plus newly emerged) occurred in 29 (53%) of 54 patients. Clinical failures occurred in 8 (15%) of 54 patients, and in 7 of these 8 cases the clinical failures occurred in those with bacteriologic failures. Ten patients relapsed clinically after completion of treatment and in 8 of them tympanocentesis for MEF culture was performed. Six of these 8 cultures were positive, and the initial pathogen was isolated in 4 of 6 (67%).

CONCLUSIONS

A high bacteriologic failure rate as well as a considerable clinical failure rate occurred among patients with AOM treated with T/S. We believe that T/S is no longer an appropriate empiric choice for the treatment of AOM in regions where high T/S resistance among respiratory pathogens is reported.

Treatment of acute otitis media - challenges in the era of antibiotic resistance

The last decade is characterized by the increase in antibiotic resistance among respiratory bacterial pathogens in the presence of only modest progress in the development of new antibacterial agents to overcome this resistance. A series of recent studies show clearly that the increased resistance among the main AOM pathogens (namely Streptococcus pneumoniae and Haemophilus influenzae) is associated with a dramatic decrease in bacteriologic response to antibiotic treatment, which in turn has an impact on clinical response. Thus, the individual patient is affected by the increasing antibiotic resistance. Moreover, the society as a whole is now also affected because the carriage and spread of antibiotic resistant AOM pathogens is remarkably impacted by antibiotic treatment. New studies show the remarkable ability of antibiotics to rapidly promote nasopharyngeal carriage and spread of antibiotic-resistant AOM pathogens. In these studies, the increase in carriage of antibiotic resistant S. pneumoniae is shown already after 3-4 days from initiation of antibiotic treatment and may last for weeks to months after treatment. Children carrying antibiotic-resistant organisms transmit those organisms to their family and to their day care centers and thus a vicious cycle is created in which increased antibiotic resistance with decreased response leads to increased antibiotic use, which in turn leads to further increase in resistance. New antibiotics are not likely to improve this situation. It is clear that the challenge in the next decade is to prevent AOM rather than to treat it. Efforts to prevent AOM include improved environmental factors, immunization with bacterial and viral vaccines and some creative measures such as prevention of colonization and attachment to epithelium of AOM pathogens. Whether these efforts will prove successful or, even if successful, will only modify the clinical and bacteriologic picture presenting new challenges, only time will tell.

treatment and prevention of otitis media

OBJECTIVE

To review and summarize recent advances in the treatment and prevention of otitis media (OM).

DATA SOURCES

A MEDLINE search (1996-March 2000) was performed to identify relevant primary and review articles. References from these articles were also reviewed if deemed important.

STUDY SELECTION AND DATA EXTRACTION

English-language primary and review articles focusing on the treatment and prevention of acute otitis media (AOM) were included. Studies focusing exclusively on OM with effusion or serous OM and chronic suppurative OM were excluded. Information regarding prevention and drug therapy was reviewed, with an emphasis placed on advances made in the last two years.

DATA SYNTHESIS

Recently, an expert panel of the Centers for Disease Control and Prevention recommended use of only three of 16 systemic antibiotics approved by the Food and Drug Administration for treatment of AOM: amoxicillin, cefuroxime axetil, and ceftriaxone. Controversy exists over the importance of key selection factors used by the expert panel in determining which antibiotics to recommend in a two-step treatment algorithm, that is, in vitro data, pharmacodynamic profiles, and necessity for coverage of drug-resistant Streptococcus pneumoniae at all steps of empiric treatment. Additional antibiotic and patient selection factors useful for individualizing therapy include clinical efficacy, adverse effects, frequency and duration of administration, taste, cost, comorbid infections, and ramifications should bacterial resistance develop to the chosen antibiotic. Presumed or past patient/caregiver adherence (especially when antibiotic failure has occurred) is also paramount in selecting antibiotic therapy. A three-step treatment algorithm for refractory AOM that employs amoxicillin, trimethoprim/sulfamethoxazole (TMP/SMX), or high-dose amoxicillin/clavulanate (depending on the prior dose of and adherence to amoxicillin therapy), and ceftriaxone or tympanocentesis at steps 1, 2, and 3, respectively, appears rational and cost-effective. The recent upsurge in antimicrobial resistance is highlighted, and recommendations are presented for the treatment of AOM and prevention of recurrent otitis media (rAOM).

CONCLUSIONS

Amoxicillin remains the antibiotic of choice for initial empiric treatment of AOM, although the traditional dosage should be increased in patients at risk for drug-resistant S. pneumoniae. In cases refractory to high-dose amoxicillin, TMP/SMX should be prescribed if adherence to prior therapy seemed good or complete, or high-dose amoxicillin/clavulanate if adherence was incomplete or questionable. Ceftriaxone should be reserved as third-line treatment. The increasing prevalence of drug-resistant S. pneumoniae emphasizes the importance of alternative medical approaches for the prevention of OM, as well as judicious antibiotic use in established cases. Removal of modifiable risk factors should be first-line therapy for prevention of rAOM. We support the use of conjugate pneumococcal vaccine per guidelines for prevention of rAOM from the Advisory Committee on Immunization Practice of the Centers for Disease Control and Prevention, with consideration given to influenza vaccine for cases of rAOM that historically worsen during the flu season. Sulfisoxazole prophylaxis should be reserved for children who are immunocompromised, have concurrent disease states exacerbated by AOM, or meet the criteria of rAOM despite conjugate pneumococcal and influenza vaccination. Therapy should be intermittent, beginning at the first sign of an upper respiratory infection, and should continue for 10 days. The invasive nature and risks of anesthesia relegate myringotomy, tympanostomy tubes, and adenoidectomy to last-line therapies for rAOM.

Colonization by Streptococcus penumoniae in human immunodeficiency virus-infected children

OBJECTIVE

Children with HIV infection are particularly susceptible to invasive pneumococcal disease, yet the effect of HIV infection and its medical management on colonization and resistance to antibiotics are poorly described. To provide a basis for medical practice, we determined the prevalence of nasopharyngeal colonization and antibiotic resistance of Streptococcus pneumoniae in children with HIV infection.

METHODS

Cross-sectional prevalence sample of children attending the pediatric HIV and pulmonary clinics to examine nasopharyngeal colonization with S. pneumoniae and antibiotic resistance to beta-lactams and trimethoprim-sulfamethoxazole (T/S). Subjects were matched by age and date of clinic visit.

RESULTS

The colonization rate with S. pneumoniae of HIV-infected and -indeterminate children was equal to that of controls (20% vs. 19%). HIV infection, CDC staging or receipt of oral antibiotic therapy did not affect colonization. Isolates from HIV-infected and -indeterminate children were less likely to be penicillin-resistant than those from controls (18% vs. 50%). There was no difference in pneumococcal resistance to T/S among isolates from subjects and controls, despite 72% T/S use in the HIV clinic.

CONCLUSION

Colonization with S. pneumoniae in HIV disease is no different from that of comparable children. The high incidence of pneumococcal disease and prophylaxis with T/S are not related to nasopharyngeal colonization. Antibiotic prophylaxis of HIV-infected children does not necessarily lead to increased resistance of S. pneumoniae.