Penicillin-resistant Streptococcus pneumoniae in Riyadh, Saudi Arabia

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.

Impact of the revised penicillin susceptibility breakpoints for Streptococcus pneumoniae on antimicrobial resistance rates of meningeal and non-meningeal pneumococcal strains

BACKGROUND AND OBJECTIVES

In January 2008, the Clinical Laboratory Standard Institute (CLSI) revised the Streptococcus pneumoniae breakpoints for penicillin to define the susceptibility of meningeal and non-meningeal isolates. We studied the impact of these changes. In addition, the pneumococcal resistance rate to other antimicrobial agents was reviewed.

DESIGN AND SETTING

Laboratory data on peumococcal isolates collected retrospectively from hospitalized children in tertiary care hospital in Riyadh, Saudi Arabia from January 2006 to March 2012.

PATIENTS AND METHODS

Only sterile samples were included from cerebrospinal fluids, blood, sterile body fluids and surgical tissue. Other samples such as sputum and non sterile samples were excluded. We included samples from children 14 years old or younger. The minimum inhibitory concentration (MIC) for penicillin, cefuroxime, ceftriaxone and meropenem were determined by using the E-test, while susceptibility to erythromycin, cotrimoxazole and vancomycin were measured using the disc diffusion methods following the guideline of CLSI.

RESULTS

Specimens were analyzed in two different periods: from January 2006 to December 2007 and from January 2008 to March 2012. During the two periods there were 208 samples of which 203 were blood samples. Full penicillin resistance was detected in 6.6% in the first period. There was decrease in penicillin nonmeningeal resistance to 1.5% and an increase in resistance in penicillin meningeal 68.2% in the second period (P=.0001). There was an increase in rate of resistance among S pneumoniae isolates over the two periods to parenteral cefuroxime, erythromycin and cotrimoxazole by 34.6%, 35.5% and 51.9%, respectively. Total meropenem resistance found 4.3% and no vancomycin resistance was detected.

CONCLUSIONS

The current study supports the use of the revised CLSI susceptibility breakpoints that promote using penicillin to treat nonmeningeal pneumococcal disease, and might slow the development of resistance to broader-spectrum antibiotics.

Antimicrobial resistance among Gram-positive pathogens in Saudi Arabia

Several species of Gram-positive cocci are major nosocomial or community pathogens associated with morbidity and mortality. Here, we review the antimicrobial resistance among these pathogens in Saudi Arabia. In the last decades, antimicrobial resistance has increased among Staphylococcus aureus in the Kingdom with a growing prevalence of both nosocomial and community methicillin-resistant S. aureus (MRSA) isolates. As yet, no vancomycin-resistant MRSA have been reported, although isolates with reduced susceptibility to the drug have been noted. Currently, the prevalence of vancomycin-resistant entrococci (VRE) is low; however, VRE has been described in the Kingdom as well as Enterococcus faecalis and E. faecium isolates with high-level resistance to penicillin, sulfamethoxazole, macrolides, tetracycline, and aminoglycosides. In recent decades, the prevalence and rate of penicillin resistance and non-susceptibility among Streptococcus pneumoniae isolates have increased in Saudi Arabia. The organism remains, however, susceptible to other beta-lactams and to quinolones. On the other hand, resistance to co-trimoxazole and tetracyclines is high and resistance to macrolides is on the increase.

Prevalence of penicillin-resistant Streptococcus pneumoniae in Kuwait

The worldwide incidence of penicillin-resistant Streptococcus pneumoniae has increased at an alarming rate during the past decade. However, there has been little published data about the extent of this problem in Kuwait. The present study was undertaken to ascertain the preponderance of S. pneumoniae, either resistant or intermediate-resistant to penicillin, other beta-lactams and non-beta-lactam antimicrobials in Kuwait. Two hundred and fifty fresh isolates from as many patients suffering from different clinical conditions were collected from all clinics and hospitals in Kuwait. Optochin sensitivity and bile solubility tests reconfirmed these. Susceptibility testing to penicillin, ampicillin, cefuroxime, ceftriaxone, cefotaxime, imipenem, erythromycin, chloramphenicol, ciprofloxacin and vancomycin was done using E-test strips and to oxacillin, tetracycline, trimethoprim and amoxicillin-clavulanate by disc diffusion technique. Full and intermediate resistance to penicillin was observed in 1.6% and 52.8% of the isolates respectively. Full resistance to third-generation cephalosporins ranged from 0.4% to 3.2%, however, intermediate resistance to these antibiotics varied between 18.8% and 21.2%. Ampicillin resistance was noted in 0.8%, but 40.4% of isolates were intermediately resistant. However, only 0.4% of the isolates showed either intermediate or full resistance to amoxicillin-clavulanate. Resistance to imipenem was observed in 0.4% and intermediate to 13.6% of the organisms. The rates of S. pneumoniae resistant to chloramphenicol, erythromycin, tetracycline and trimethoprim were between 8.4% and 37.6% and intermediate resistance between 1.2% and 17.6% while only 0.4% showed resistance to ciprofloxacin and none to vancomycin. Multiresistance to both beta-lactam and non-beta-lactam antibiotics was observed in 52% of the penicillin-resistant isolates.

Antimicrobial resistance of Streptococcus pneumoniae at a university hospital in Saudi Arabia

The resistance pattern of 105 consecutive strains of Streptococcus pneumoniae isolated from patients at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia over a 2-year period (March 1998 to February 2000) was determined with the minimal inhibitory concentration (MIC) method using E-test. Overall 6.7% of the isolates were penicillin resistant (MICs > or = 2 mg/L), and 51% were intermediate (MICs 0.12-1 mg/L). The resistance rates to ampicillin, cefotaxime, ceftriaxone, imipenem, erythromycin and clarithromycin were 8.6%, 8.6%, 4.7%, 3.8%, 13%, and 21% respectively. High-level resistance was noted against cotrimoxazole and chloramphenicol, 76% and 68% respectively. Only 2.8% of S. pneumoniae were resistant to amoxycillin-clavulanate; no resistance to vancomycin was observed. Against penicillin-intermediate pneumococcal strains, vancomycin, ceftriaxone, cefotaxime and amoxycillin-clavulanate were the most active compounds. Against penicillin-resistant pneumococci, vancomycin was the most powerful agent, amoxycillin-clavulanate was half as active, whereas ceftriaxone, cefotaxime and imipenem were 4-fold less active than vancomycin. Fifty-six (53%) of the 105 pneumococcal strains were multi-drug resistant.

Penicillin-resistant and -intermediate Streptococcus pneumoniae in Saudi Arabia

The antibiotic susceptibility was analyzed of approximately 400 consecutive isolates of S. pneumoniae isolated from different regions of Saudi Arabia. Most of these isolates were from respiratory (sputum, otitis, 53.8%), blood/CSF (26.3%) and ophthalmic (20%) specimens. Overall 6.2% of the isolates were penicillin-resistant (MICs > or =2 microg/ml) and 51.2% were -intermediate (MICs 0.1-1 microg/ml). The resistance rates to cefuroxime, clarithromycin and ceftriaxone were 14.9%, 14.8% and 4.5% respectively. Only 3.5% of S. pneumoniae showed resistance to amoxycillin/clavulanic acid. The MICs of all tested antibiotics increased as did the penicillin MICs. Penicillin resistance was significantly associated with resistance to cefuroxime (p<0.001) but not with the others. These data indicate the presence of penicillin and multiple-resistant pneumococci in Saudi Arabia and that these strains can spread among individuals. A greater awareness with extended indications for microbiological diagnosis, antimicrobial susceptibility testing and restrictive prescription of antibiotics are needed.

Drug-resistant Streptococcus pneumoniae in the Lebanon: implications for presumptive therapy

A total of 50 consecutive clinical isolates of Streptococcus pneumoniae, collected between 1996 and 1998, were tested against six antimicrobial agents using the E-test. The percentages of fully resistant (R) and intermediately-R strains, respectively, were: benzyl penicillin 18 and 38%, amoxycillin-clavulanate 6 and 12%, cefuroxime 22 and 16%, ceftriaxone 2 and 16%, and clarithromycin 10%. Fully and or intermediately multidrug-resistance (two or more drugs) was seen in 44% of the isolates, 18% being fully resistant. The MIC breakpoint for cefaclor is not defined by the National Committee for Clinical Laboratory Standards (NCCLS) but MICs showed that: 76% of the isolates had an MIC of < or = 8 mg/l, 4% had an MIC of 16 mg/l and 20% had an MIC of > or = 32 mg/l. There was agreement between the E-test Pen MIC results and the 1 microg oxacillin (oxa) disk diffusion screen test for the 22 susceptible and the nine fully R strains but not for the 19 strains with Pen MICs between 0.1 and 1 mg/l; this shows the importance of MIC determination in such isolates. Penicillin and multiply antibiotic-resistant pneumococci are spreading in Lebanon, emphasizing the necessity to reconsider current treatment regimens in this country.

Childhood pneumococcal bacteraemia in Riyadh, Saudi Arabia

Forty-nine children with pneumococcal bacteraemia seen during a 5-year period (1 January 1991 to 31 December 1995) at King Khalid University Hospital were studied. The majority (61.2%) were under 2 years of age. The focus of infection was pneumonia, pharyngitis or undetermined in 28.6%, 18.4% and 20.4%, respectively. Diseases that had probably predisposed them to pneumococcal bacteraemia (mainly nephrotic syndrome) were encountered in 24.5% of cases. Forty-five per cent of the cases occurred during the summer season and in 29% the disease was nosocomially acquired. No death was recorded in this series and the reasons for this are discussed. Detection of pneumococcal antigens from blood taken for culture was successful in 96% of cases; this test is important in the diagnosis of pneumococcal bacteraemia in partially treated patients. Antimicrobial susceptibility testing showed 20.4% of the isolates to be relatively penicillin-resistant. Resistance to other antimicrobial agents was also recorded and multiple resistance was noted in 22% of isolates. There was a significant difference between the ceftriaxone MIC of the relatively penicillin-resistant strains compared with penicillin-sensitive strains. The emergence and the steady increase in the numbers of relatively penicillin-resistant pneumococcal strains in Saudi Arabia during the last 10 years are discussed.