Failure of the conjugate pneumococcal vaccine to prevent recurrent bacteremia in a child with human immunodeficiency virus disease

Recurrent pneumococcal invasive disease in the region of Madrid during a five-year period

PURPOSE

The aim of this study was to describe the clinical and microbiological characteristics of recurrent invasive pneumococcal disease (RIPD) cases identified in the Region of Madrid between January 2007 and December 2011.

METHODS

Streptococcus pneumoniae serotyping was performed by Pneumotest-Latex and Quellung reaction. Molecular typing was carried out by pulsed-field gel electrophoresis (PFGE). A relapse was defined as any case of RIPD caused by strains with similar PFGE profile. Re-infections were defined by detection of recurrent episodes caused by strains with different PFGE patterns.

RESULTS

During the study period, 2,929 S. pneumoniae strains isolated from 2,858 patients with invasive pneumococcal disease (IPD) were studied. In 61 patients (2.1 %), 132 episodes of RIPD were detected (two episodes in 52 patients, three in 8 and four in 1). Twelve patients had relapses, 47 had re-infections and two had re-infections followed by relapses. Common risk factors to developing RIPD were HIV (42.6 %) and haematological malignancies (16.4 %). The most frequent serotypes were 8 (16 episodes) and 19A (15 episodes). Fourteen strains that were resistant to levofloxacin were also resistant to erythromycin. The proportion of strains co-resistant to erythromycin and levofloxacin was significantly higher in relapses (11/29) than in re-infections (3/103).

CONCLUSIONS

The occurrence of repeated episodes of IPD in the same patient over the time is not an exceptional issue. Some underlying conditions that may favour these recurrences, mainly immunosuppression, need to be considered in patients having an episode of IPD.

Breakthrough Streptococcus pneumoniae type 6B infection after adrenocorticotropic hormone therapy in a child vaccinated with pneumococcal conjugate vaccine

Despite proven good efficacy of pneumococcal conjugated vaccine in preventing invasive pneumococcal disease, breakthrough infections remain a noticeable problem with significant morbidity and mortality, especially in selected high-risk groups. We present a 2-year-old girl with infantile spasm, who was treated with antiepileptic drugs and adrenocorticotropic hormone (ACTH). Vaccination with three doses 7-valent pneumococcal conjugate vaccine had been completed one month before ACTH therapy. Two months after ACTH therapy, she suffered from fever, cough, and decreased activity. Streptococcus pneumoniae, serotype 6B, was detected in blood culture. Vaccine failure could be possibly due to ACTH therapy.

[Pneumococcal conjugate vaccine failure in HIV-infected child. Clinical case]

Despite appropriate antimicrobial therapy and vaccination, invasive pneumococcal infections remain associated with significant mortality, especially in selected high-risk groups (asplenic, humoral immunity deficient patients, etc.). We present a 13-year-old caucasian boy with HIV infection (vertical transmission). He received treatment with highly-active antiretroviral therapy (amprenavir, lamivudine and zidovudine) and vaccination with 23-valent vaccine (6 years old) and 7-valent pneumococcal conjugate vaccine (10 years old). His CD4 count and his viral load at these times were 2,063/microl and 13461 cop/ml, when he was 6 years old and 1,315/microl and 32400 cop/ml when he was 10 years old, respectively. The latest CD4 count (1,000/microl) and his viral load (3800 cop/ml) confirmed satisfactory control of the disease. He was referred to our emergency department presenting with fever, head and stomach-ache and vomiting. In the following hours his condition continued to deteriorate and depressed level of consciousness and meningismus were observed. Streptococcus pneumoniae, serotype 18 C, was detected in blood and cerebrospinal fluid cultures. Despite appropriate treatment with antibiotics (cefotaxime and vancomycin) and anti-oedema medications, brain-death was confirmed 24 hours after his admittance.

Immunogenicity and efficacy of childhood vaccines in HIV-1-infected children

Children infected by HIV-1 are particularly vulnerable to severe, recurrent, or unusual infections by vaccine-preventable pathogens. Routine immunisations seem to be generally safe for HIV-1-infected children, but responses may be suboptimal. Early HIV-1-induced immune attrition associated with viral replication may particularly interfere with the development of memory responses. In high HIV-1 prevalence regions, the accumulation of susceptible hosts may compromise disease-control efforts. Although early control of viral replication through treatment with highly active therapy may preserve immune function and responses to routine childhood vaccines, availability is limited in the areas most affected. In this review, we provide an overview of the immunogenicity and efficacy of childhood vaccines in HIV-1-infected children. The possible immunological bases for defective responses are discussed; unanswered questions and the need for further research are delineated.