Streptococcus pneumoniae serotypes / serogroups causing invasive disease in Riyadh, Saudi Arabia: extent of coverage by pneumococcal vaccines

Serogroup distribution of sterile site pneumococcal isolates varies between developing and developed countries as well as between different geographical regions. The potential efficacy of any pneumococcal vaccine depends on the degree of representation of the prevalent serogroups in the vaccine. We conducted this study to determine the prevalent pneumococcal serogroups causing invasive infections in Riyadh, Saudi Arabia and to estimate the coverage by the various pneumococcal conjugate vaccines. S. pneumoniae isolated between February 2000 and November 2001 from sterile sites of patients of all age groups were collected from 8 major hospitals in Riyadh and serogrouped using the latex agglutination method. Isolates from 78 patients, 72% of whom were children, were studied. Eighty-eight percent of the isolates belonged to only 10 serogroups/serotypes, namely 6 and 19, 1 and 15, 14 and 23, 7, 18 and 22, in descending order of frequency. Potential coverage of the 7-valent, 9-valent, and 11-valent conjugate vaccines were 54%, 65% and 73%, respectively. The rate of reduced penicillin susceptibility in the serogroups represented in the 7-valent conjugate vaccine was significantly higher than in the non-vaccine serogroups [62% vs. 25%; P=0.0023]. The currently available 7-valent pneumococcal conjugate vaccine provides sub-optimal coverage to serogroups causing invasive diseases in our community. However, this vaccine would be a useful adjunct to penicillin prophylaxis in at-risk patients in the community. The effectiveness of the vaccine would be greater if serotype 15 could be included

Bloodstream infections in pediatric patients

Blood stream infection [BSI] is the leading cause of morbidity and mortality in pediatric patients. This study aims to describe the clinical, microbiological characteristics and outcome of BSI in pediatric patients. We collected the clinical data from all pediatric patients with positive blood cultures. We identified all isolates from these patients from January 2004 to December 2004 at King Khalid University Hospital [KKUH], Riyadh, Saudi Arabia, and determined antimicrobial susceptibilities by MicroScan Walk Away 96 [Dade Behring Inc., West Sacramento, CA95691, USA]. Two hundred and twenty pediatric patients had BSI, of whom 147 [67%] were males and 71 [32.2%] were from intensive care units [ICUs]. Two hundred and ten [95.4%] had single blood culture isolate. One hundred and seventy-three [78.6%] of the isolates were Gram positive bacteria and included the following: Staphylococcus epidermidis [55.4%], Staphylococcus aureus [9.5%] of which 14% were methicillin resistant, Streptococcus pneumoniae [S. pneumoniae] [4.5%], 40% of which were resistant to penicillin and Enterococcus faecalis [4%]. Gram negative bacteria were 44 [20%] and included Escherichia coli and Klebsiella pneumoniae [K.pneumoniae] [3.6% each]. Three isolates [1.3%] were Candida glabrata. None of the Gram positive isolates were vancomycin resistant. Three K. pneumoniae and one Pseudomonas spp. isolates were multiresistant. One hundred and ninety-four [88%] of BSI isolates were hospital acquired. Fever was the most common presentation of pediatric patients [26%] with positive blood culture with no apparent focus of infection. Respiratory tract infections 26 [12%] were the next most common. We seen sepsis in [7.7%] children between 8 days and 6 months of age. Bone and joint infections, cardiac, renal, gastrointestinal diseases, malignancy and surgical cases were other associated clinical diagnoses of BSI in pediatric patients. Patients with immuno- suppressive disorders with BSI had isolates such as Salmonella spp., S. pneumoniae and Pseudomonas spp. Overall mortality was 13 [6%] [p<0.005] and those patients had underlying serious medical conditions with associated risk factors such as prolonged hospital stay, intensive care unit [ICU] admission, indwelling catheterization, mechanical ventilation and prior antimicrobial use. Bloodstream infection is an important cause of morbidity and mortality in pediatric patients. Risk factors for hospital acquired infection include: prematurity, prolonged hospitalization, ICU admission, indwelling catheterization, mechanical ventilation and prior antimicrobial therapy

Pencillin resistance in serogroups/serotypes of streptococcus pneumoniae causing invasive infections in central Saudi Arabia

To determine the minimum inhibitory concentrations [MICs] of penicillin, ceftriaxone and vancomycin of serogroups/serotypes of Streptococcus pneumoniae [S. pneumoniae] from invasive diseases in all age groups from major hospitals in Riyadh, Kingdom of Saudi Arabia [KSA]. All isolates of S. pneumoniae from patients with invasive pneumococcal infections between February 2000 and November 2001 were prospectively collected from 8 major hospitals in Riyadh, KSA. The isolates were confirmed as S. pneumoniae at the King Khalid University Hospitals, Riyadh, KSA and then serogrouped/serotyped using the agglutination method. The MICs for penicillin, ceftriaxone and vancomycin were carried out using the E-test. Forty-three% of the isolates were resistant to penicillin mostly of the intermediate type [97%]. The resistant strains were mainly confined to serogroups/serotypes 6, 23, 19 and 15 and the 7-valent conjugate vaccine covers 76% of the penicillin-resistant strains. Only one isolate was resistant to ceftriaxone. In view of the rather insignificant level of highly resistant-penicillin strains and the virtual absence of resistance to ceftriaxone we would like to suggest using ceftriaxone for treating invasive pneumococcal infections outside the central nervous system. We recommend that the conjugate vaccine would be a useful adjunct to penicillin prophylaxis in patients at risk in our community

Nocardial pulmonary infection in a non-compromised patient

This report describes nocardial pulmonary infection in a lady with bronchiectasis who was otherwise not immunocompromised. She was successlly treated with co-trimoxazole [160 mg trimethoprim + 800 mg sulphamexazole orally 12 hourly]. The first indication of the presence of nocardial infection was the detection of branching gram positive bacilli in the sputum