Vaccination against invasive pneumococcal disease in Saudi Arabia: where do we stand?

Serological and molecular capsular typing, antibiotic susceptibility of Streptococcus pneumoniae isolates from invasive and non-invasive infections

Streptococcus pneumoniae causes life threatening infections and necessitate for impediment and controlling disease; to conquer this, information is needed about serotype distribution and patterns of antibiotic resistance. The present study was to determine the serotype distribution of S. pneumoniae isolated from the entire age group individual and to correlate this distribution with susceptibility. Cases of pneumococcal infections have been reviewed for serotyping and antibiotic susceptibility. Out of 117 pneumococcal isolates 45 (39%) were penicillin-resistant, 84 (72%) were erythromycin-resistant and 100% were co-trimoxazole resistant. The most frequently isolated serotypes were 23F, 19F, 14, 6B, 5, 6A, 19A and 9V. PCV7, PCV10 and PCV13 coverage was 68%, 79%, 87%, respectively. Similarly, there was similarity in PCV7 coverage for non invasive isolates (64.5%) and invasive isolates (72.2%). The study state that common pneumococcal serotypes were present in similar ways as reported in literature. A continuous survey of pneumococcal infected population is requirement and necessity for success of vaccination.

Antibiotic resistance and serotype distribution of invasive pneumococcal diseases before and after introduction of pneumococcal conjugate vaccine in the Kingdom of Saudi Arabia (KSA)

Streptococcus pneumoniae is one of the most common bacterial causes of morbidity and mortality worldwide, causing life threatening infections such as meningitis, pneumonia and febrile bacteremia, particular among young children. The severity and frequency of S. pneumoniae infection and emergence of drug-resistant isolates have highlighted the need for prevention of invasive pneumococcal disease (IPD) as the best method for controlling disease; to better achieve this, more information is needed about serotype distribution and patterns of antibiotic resistance in children in the Kingdom of Saudi Arabia (KSA). Cases of pneumococcal infections in children aged <5 years, recorded in hospitals throughout KSA from 2005 to 2010 were reviewed for serotyping and for antibiotic susceptibility. This covers the time period just before limited introduction of 7-valent pneumococcal conjugate vaccine (PCV7) in 2006, to its introduction into the national immunization program in 2008, until right after a switch to PCV13 in 2010. Case definition required isolation of S. pneumoniae from blood, cerebrospinal fluid, or any sterile biological fluid. Isolates from 311 eligible cases were collected from different regions across KSA, 250 from blood and 61 from cerebrospinal fluid. The most frequently isolated IPD serotypes were 23F, 19F, 6B, 5 and 1. Over the course of the study, there was significant rise of serotype 19A (covered by PCV13 but not PCV7), which accounted for 20% of isolates of IPD in Western and 5% in Central regions in the last 2 years in KSA. There was a notable decrease in serotype 18C over this period, one of the PCV7 serotypes. Serotype coverage for PCV7, PCV10, PCV13 in children <5 years was 53%, 80%, and 91%, respectively across the Kingdom from 2005 to 2010. A total of 66% of IPD isolates were penicillin-resistant, and 62% were erythromycin-resistant. Continued surveillance is critical to measure the emerging of new serotypes and antibiotic resistance strain, and the potential impact of new PCVs. PCV13, recently introduced into the national immunization schedule in place of PCV7, provides the widest coverage among all IPD serotypes across KSA.

Epidemiology of invasive pneumococcal infection in children aged five years and under in Saudi Arabia: a five-year retrospective surveillance study

BACKGROUND

The epidemiology of invasive pneumococcal disease (IPD) in children aged <or=5 years in Saudi Arabia has not been described. We conducted a retrospective surveillance study to describe the epidemiology of IPD in the population of children aged <or=5 years served by the National Guard Health Affairs hospitals in central and western regions of Saudi Arabia.

METHODS

We reviewed the medical records of children <or=5 years old admitted to the King Abdulaziz Medical City hospitals in Riyadh and Jeddah with pneumococcal infections for the period January 1999 through December 2003. Only microbiologically confirmed IPD cases (meningitis or bacteremia) were included in the analysis.

RESULTS

A total of 82 IPD cases, 19 (23.2%) meningitis and 63 (76.8%) bacteremia, were diagnosed during the five-year period. Of these, 12.2% (10/82) died, with a case-fatality slightly but insignificantly higher in cases of meningitis (15.8%) than bacteremia (11.1%). The average annual IPD incidence was 17.4 per 100,000 (4.0 for meningitis and 13.4 for bacteremia). The incidence was roughly similar in males and females (18.3 and 16.6, respectively; p=0.663) and was almost 4-fold higher in the first year of life compared to the next four years (40.6 and 11.5, respectively; p<0.001). The average annual IPD mortality was 2.1 per 100,000 and was higher in the first year of life compared to the next four years (5.2 and 1.3 , respectively; p=0.043).

CONCLUSIONS

In the pre-vaccination era (1999-2003) in Saudi Arabia, IPD incidence was comparable to the pre-vaccination incidence rates from many industrialized countries, with children aged <or=1 year suffering the highest IPD risk among those aged <or=5 years.

Emergence and trends of penicillin non-susceptible Streptococcus pneumoniae in Saudi Arabia and Kuwait - perspective and outstanding issues

For many years in the past Streptococcus pneumoniae was uniformly susceptible to penicillin until the sudden and unexpected emergence of clinical infections caused by penicillin-resistant S. pneumoniae (PRSP) in 1967. Within the following decade, reports of nosocomial and community outbreaks of infections due to PRSP became widespread all over the world. Recent reports suggest that the incidence of resistance rates is rising in many countries although there are geographical variations in the prevalence and patterns of resistance between countries. The problem of antibiotic resistance is further compounded by the emergence of resistance to many beta-lactam antibiotics. The first report of PRSP in Saudi Arabia was in 1991. Barely a year after, PRSP infection was reported in Kuwait in 1992. Since then, studies from various parts of these countries have recorded prevalence rates ranging from 6.2% in Riyadh to 34% in Jeddah and 20% to 56% in neighboring Kuwait. These suggest considerable variation in the prevalence of PRSP in different cities in the Saudi Kingdom and Kuwait. The mechanism of resistance is due to chromosomally mediated alteration of penicillin-binding proteins (PBPs), which are target sites for beta-lactam antibiotics. It would appear that the spread of PRSP strains in Saudi Arabia is driven by the selective pressure created by excessive use and misuse of antimicrobial agents made possible by the easy availability of these agents, often frequently obtainable over the counter. In Kuwait, irrational and misguided use of antibiotics may be the major driving force favoring the spread of PRSP. The serotypes of strains encountered in Saudi Arabia and Kuwait are almost identical, with serotypes 19, 6, 15, 14 and 23 being the most common; together they constitute about 70% of the isolates circulating in these countries. In general, almost 90% of the serotypes included in the 23-polyvalent vaccine are present in the general population. However, a much lower percentage of these serotypes is found in the conjugated vaccines, which are more relevant to our communities. This paper reviews the emergence and the steady increase in the prevalence of penicillin-resistant pneumococcal strains in Saudi Arabia and Kuwait during the last 10 years. It discusses the trends, mechanisms of resistance and factors associated with the emergence, dissemination, and colonization of resistant organisms and suggests options available to clinicians for management of infections due to PRSP.

Childhood meningitis in Kuwait: epidemiology of etiologic agents and the need for pneumococcal disease prevention

OBJECTIVE

To investigate the epidemiology of the etiologic agents causing bacterial meningitis in Kuwait.

SUBJECTS AND METHODS

This is a retrospective analysis of the medical records of children 1 month to 12 years old who had cerebrospinal fluid (CSF) findings consistent with meningitis. Patients were identified from the records of the Departments of Microbiology and Communicable Diseases in six regional hospitals during 2001. They were divided into bacterial and viral infective groups.

RESULTS

Ninety children had CSF findings consistent with meningitis, 44 bacterial (23 culture proven, 21 probable) and 46 viral. Streptococcus pneumoniae and Neisseria meningitidis were the most frequently isolated organisms (44 and 30%, respectively). A 2-month-old child had Haemophilus influenzae and was the only mortality of this series. S. pneumoniae is the leading bacterial agent causing meningitis in children under the age of 1 year; 61% had bacterial meningitis compared to 37% with viral meningitis. Sequelae were encountered in 23% of bacterial cases.

CONCLUSION

The results indicate that S. pneumoniae is the leading bacterial agent causing meningitis, indicating a need for the introduction of polyvalent pneumococcal vaccine.