Khalid M. Bindayna

Exploring the evidence base for national and regional policy interventions to combat resistance

The effectiveness of existing policies to control antimicrobial resistance is not yet fully understood. A strengthened evidence base is needed to inform effective policy interventions across countries with different income levels and the human health and animal sectors. We examine three policy domains-responsible use, surveillance, and infection prevention and control-and consider which will be the most effective at national and regional levels. Many complexities exist in the implementation of such policies across sectors and in varying political and regulatory environments. Therefore, we make recommendations for policy action, calling for comprehensive policy assessments, using standardised frameworks, of cost-effectiveness and generalisability. Such assessments are especially important in low-income and middle-income countries, and in the animal and environmental sectors. We also advocate a One Health approach that will enable the development of sensitive policies, accommodating the needs of each sector involved, and addressing concerns of specific countries and regions.

Prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae in Bahrain.

OBJECTIVES To determine the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Bahrain. METHODS Retrospective analysis of records (January 2005-December 2006) at the Microbiology Laboratory of the Salmaniya Medical Complex, Bahrain which is the major national diagnostic laboratory. RESULTS Out of a total of 11,886 member of family of Enterobacteriaceae isolated, 2695 (22.6%) were ESBL producers. Majority of ESBL isolates were from inpatients (n=2363; 87.7%). Escherichia coli (52.2%) and Klebsiella pneumoniae (24.3%) were predominant and distributed comparatively in the hospital wards while Proteus spp. (17.6%) was predominant in medical wards. Urine was the major source (52.2%) with low occurrence in blood cultures. No carbapenem resistant isolates was identified but resistance to three classes of antibiotics was exhibited by >25% of the isolated ESBL strains. Nitrofurantoin resistance was identified in 38.2% of urinary isolates. CONCLUSION This is the first report from Bahrain and it indicates that the prevalence of ESBL-producing isolates is high. Carbapenems were the most active drug against the ESBL-producing isolates. We recommend strict infection control to prevent trafficking into the community.

Diversity of plasmid-mediated carbapenem-hydrolysing oxacillinases among carbapenem-resistant Acinetobacter baumannii isolates from Kingdom of Bahrain

Sir, Carbapenem resistance in Acinetobacter baumannii is now increasingly reported. The most prevalent mechanism of carbapenem resistance in A. baumannii corresponds to the production of acquired carbapenem-hydrolysing class D b-lactamases (CHDLs) encoded by blaOXA-23-like, blaOXA-40-like or blaOXA-58-like genes. Whereas the blaOXA-40 gene has been detected in Portugal, Spain and the USA, blaOXA-23 and blaOXA-58 genes have disseminated worldwide. 1 The aim of our study was to identify the molecular mechanisms leading to carbapenem resistance among a panel of A. baumannii isolates exhibiting resistance or intermediate susceptibility to imipenem and collected from September 2007 to March 2008 in the Salmaniya Medical Complex, Kingdom of Bahrain, which is a 1000 bed tertiary care centre. A total of 454 A. baumannii isolates had been recovered during the studied period, among which 262 (58%) were resistant or intermediately susceptible to imipenem. Among the latter, eight randomly selected A. baumannii isolates collected from eight patients hospitalized in different units were further analysed. They were identified using the API20 NE system and 16S rRNA gene sequencing. All isolates had been recovered from deep tracheal aspirates. Although two isolates were considered as colonizers, six were involved in infections and, among those, four were responsible for septicaemia that led to the death of all these patients. Use of Etest strips (AB Biodisk, Solna, Sweden) combining imipenem and EDTA did not identify metallo-b-lactamase in the isolates. PCR experiments followed by sequencing as described previously led to the identification of CHDL genes. A blaOXA-23 gene was found in two isolates (1 and 2), preceded by insertion sequence ISAba1 as observed in transposon Tn2006; but no ISAba1 copy was identified downstream of blaOXA-23. Isolate 3 harboured a blaOXA-58 gene that was bracketed by two copies of ISAba3, as described previously. Five isolates possessed a blaOXA-40-like gene, and further sequencing revealed that this gene corresponded to blaOXA-72. The OXA-72 b-lactamase belongs to the OXA-40 subgroup together with OXA-25 and OXA-26 b-lactamases. The OXA-40-type b-lactamases differ by no more than five amino acids and possess weak carbapenemase properties. OXA-72 had been previously reported in a single Acinetobacter genomospecies 3 isolate in China, in a single Acinetobacter baylyi isolate in Korea and in several carbapenem-resistant A. baumannii isolates in Taiwan. Genotypic comparison was performed by PFGE, as described previously. The two OXA-23 producers (isolates 1 and 2) were clonally related (pulsotype I). The single blaOXA-58-positive isolate belonged to pulsotype II. The remaining blaOXA-72positive isolates belonged to pulsotype III (isolates 4 and 5), IV (isolates 6 and 7) or V (isolate 8). All isolates were resistant to ticarcillin and piperacillin, and isolates carrying genes encoding CHDLs OXA-23 and OXA-72 were highly resistant to imipenem and meropenem, although the OXA-58 producer displayed lower MICs of imipenem and ceftazidime (Table 1). Mating-out experiments were performed as described previously, with OXA-23-, OXA-58and OXA-72-positive isolates as donors and rifampicin-resistant A. baumannii BM4547 as the recipient strain. The transconjugants were selected on agar plates containing ticarcillin (50 mg/L) and rifampicin (50 mg/L). Transconjugants were obtained only with blaOXA-23-positive donors, and the transconjugants showed resistance to ticarcillin and decreased susceptibility to carbapenems (Table 1). The transconjugants harboured a 130 kb plasmid additionally conferring resistance to kanamycin and amikacin (data not shown). Plasmid extracts, obtained as described previously, with OXA-58and OXA-72-positive donors were used for transformation experiments with A. baumannii BM4547 as the recipient strain. Electrotransformation products were selected on plates containing ticarcillin (50 mg/L). Electroporation of plasmid extracts gave rise to A. baumannii BM4547 (pOXA-72) transformants, whereas no transformant was obtained with the OXA-58-positive donor strain. The blaOXA-72 gene was located on a 10 kb plasmid in all OXA-72-positive isolates. The blaOXA-72-positive A. baumannii transformants showed resistance to ticarcillin and decreased susceptibility to carbapenems (Table 1), without any additional antibiotic resistance marker. In order to investigate the genetic structures surrounding the blaOXA-72 gene, cloning experiments were also performed. Total DNA of A. baumannii isolate 4 was digested with the SacI or HindIII restriction enzymes, ligated into corresponding sites of plasmid pBK-CMV and transferred by electroporation into Escherichia coli TOP10 as described previously. E. coli strains harbouring recombinant plasmid pBK-OXA-72 were selected on agar plates containing ticarcillin (50 mg/L) and kanamycin (30 mg/L). Detailed sequence analysis of pBK-OXA-72 showed that a gene encoding a putative inner membrane protein was present 300 bp upstream of blaOXA-72, whereas downstream a gene Journal of Antimicrobial Chemotherapy (2009) 63, 1071–1077 doi:10.1093/jac/dkp052 Advance Access publication 27 February, 2009

Neonatal Sepsis 1991–2001: Prevalent Bacterial Agents and Antimicrobial Susceptibilities in Bahrain

Objectives: To investigate the organisms causing neonatal sepsis and their modifications over an extended period, to assess their changing sensitivities to antibiotics and to verify whether the policy for screening pregnant women for group B streptococci (GBS) carriage is desirable in our settings. Subjects and Methods: Medical records of all infants with positive blood culture from the Neonatal Intensive Care Unit at Salmaniya Medical Complex between 1991 and 2001 and Bahrain Defense Force Hospital between 1999 and 2001 were reviewed. Results: Of the 7,978 neonates in both hospitals 335 (4.19%) had culture-proven bacteremia. Gram-positive bacteria were isolated at constant rate over the 11-year period. The main agents isolated were coagulase-negative Staphylococcus (CoNS) in 138 cases (41%), Staphylococcus aureus in 28 newborns (8%) and GBS in 26 patients (7.8%, 0.2/1,000 live births). All of them were sensitive to penicillin G, erythromycin and clindamycin. Gram-negative bacteria were declining but Escherichia coli was isolated in 35 cases (10%). Of special concern is the increasing percentage (5.7%) of Candida isolation. No clear trend toward increasing resistance was observed, although a major difference among the two institutions was evident. Klebsiella and Enterobacter spp. showed resistance to many of the antibiotics tested, thereby posing difficult therapeutic choices. Conclusion: Good quality specimens are essential to evaluate the role of CoNS. The increasing threat of fungal infection must be carefully tackled. Specifically tailored policies for GBS prevention must be defined according to the local epidemiology.

vacA genotypes in Helicobacter pylori strains isolated from patients with and without duodenal ulcer in Bahrain

BackgroundThe vacuolating cytotoxin and the cytotoxinassociated protein, encoded by vacA and cagA, respectively, are important virulence determinants of Helicobacter pylori.ObjectiveThe aim of this study was to perform vacA genotyping and evaluate its association with cagA genotype and clinical outcome.MethodsOne hundred and twenty H. pylori strains were isolated from dyspeptic patients (29 with peptic ulcer, 91 with non-ulcer dyspepsia). Genotype was determined by PCR.ResultsSeventy-nine (66%) of 120 strains had the vacA signal sequence genotype s1 and 41 (34%) had the type s2. The vacA middle-region types m1 and m2 were detected in 56 (47%) and 64 (53%) strains, respectively. The combinations s1-m1 (n=56 [47%] and s2-m2 (41 [34%]) occurred more frequently than s1-m2 (23 [19.2%]; p=0.001). No strain with the combination s2-m1 was found. All patients with peptic ulcers harbored type s1 strains compared to 75 (82.4%) of 91 patients with non-ulcer dyspepsia (p=0.01). The vacA genotype s1 was associated with the presence of cagA (p <0.0001). The cagA gene was detectable in 38 (31.6%) of 120 isolates and present in all 29 patients with ulcer compared to nine of 91 with non-ulcer dyspepsia (p <0.001).ConclusionHelicobacter pylori strains of vacA type s1 and the combination of s1-m1 were associated with peptic ulceration and the presence of cagA gene.

Chromosomal resistance to antibiotics in gonococci from bahrain

Ninety-one isolates of non-penicillinase-producing Neisseria gonorrhoeae from patients in Bahrain were tested for serotype, auxotype, and antibiotic susceptibility. Ten serovars and three auxotypes were found. Of the 91 isolates, 49 (54%) were serovar IB-5/7, 59 (65%) had a penicillin MIC greater than or equal to 1 mg/l, 39 (45%) had a cefuroxime MIC greater than or equal to 0.5 mg/l, and 63 (69%) had a tetracycline MIC of greater than or equal to 4 mg/l. No spectinomycin or high-level tetracycline resistance was seen. Seventy of the 91 isolates were tested against ciprofloxacin and ceftriaxone, and 40 (57%) and 26 (37%) had MICs greater than or equal to 0.03 mg/l, respectively. DNA from two penicillin-resistant isolates was capable of transforming recipient strain FA19 to donor level of penicillin and cephalosporin resistance in four steps. The first three steps were indicative of the acquisition of known resistance mutations. The existence of the fourth level transformants, with the ability of donor DNA to transform strain FA140 to higher levels of resistance, suggest the presence of another resistance mutation.

High prevalence of blaCTX–M in Enterobacteriaceae isolates from the Kingdom of Bahrain

OBJECTIVE To determine the molecular epidemiology of extended-spectrum β-lactamase (ESBL) by testing a cohort of clinical ESBL-producing bacterial isolates that were isolated in the Kingdom of Bahrain. METHODS ESBL producing Enterobacteriaceae isolates (based on phenotypic tests) were collected from Microbiology Laboratory of the Salmaniya Medical Complex, Bahrain between January-June 2006. Antibiotic susceptibility to a panel of antibiotics was performed and bla(CTX-M) genes were detected by multiplex PCR. RESULTS A total of 230 isolates (Escherichia coli, n=180; Klebsiella pneumoniae, n=50) were studied, 98% were CTX-M type. For Escherichia coli isolates, 65 (36.1%) harbored CTXM+TEM combination and 68 (37.8%) had CTX-M alone. In contrast, for Klebsiella pneumoniae isolates only 5 (10.0%) harbored the CTX-M combination, and none had CTX-M only. The bla(CTX-M) gene was found predominantly in urine isolates (n=145/230; 63.0%). Sensitivity to imipenem and nitrofurantoin was 100% and 60%, respectively. CTX-M carriage was associated with the resistance to fluoroquinolones, trimethoprim-sulfamethoxazole and aminoglycosides. CONCLUSIONS Our study documentes high prevalence of CTX-M ESBL type among Escherichia coli and Klebsiella from the Kingdom of Bahrain. The apparent dissemination of CTX-M producers could represent a substantial barrier in the treatment of community-acquired infections. The use of extended-spectrum cephalosporins, quinolones, and aminoglycosides is compromised, leaving carbapenems as the therapeutic option for severe infections caused by ESBL producers.

Characterization of cephalosporin-resistant clinical Enterobacteriaceae for CTX-M ESBLs in Bahrain

OBJECTIVE To detect the presence of specific CTX-M class of extended spectyum β-lactamases (ESBLs) in a collection of cephalosporin-resistant Enterobacteriaceae isolates from Bahrain. METHODS A subset of 80 cephalosporin-resistant Enterobacteriaceae collected from Salmaniya Medical Complex, Bahrain, were characterized further for the presence of specific genogroups of CTX-M β-lactamases by multiplex- and monoplex- PCRs. The primers used for the multiplex and monoplex PCRs were of genogroups- 1, 2, 8, 9 and 25. Sequencing of the representative isolates was performed to find the circulating CTX-M-types. RESULTS A total of 93.8% (75/80) isolates showed the amplicons corresponding to any of the genogroups (1, 2, 8, 9, 25) and the remaining 6.2% isolates turned out negative in multiplex PCR. Some of the isolates demonstrated multiple bands corresponding to the sizes of different genogroups. Further confirmation with respective monoplex PCR on these 75 isolates demonstrated that 93.3% (70/75) harbored CTX-M genogroup-1 and 6.7% (5/75) harbored genogroup-9. We did not find the presence of genogroups 2, 8, and 25 in these isolates by monoplex PCR. Sequencing results of genogroup-1 isolates demonstrated the presence of CTX-M-15-like ESBL, however, discrepant results were noticed in genogroup-9 isolates, sequencing showed them as CTX-M-55-like ESBL. CONCLUSIONS This is the first report from Bahrain characterizing the CTX-M genogroups of ESBLs and reporting the emergence of blaCTX-M-55-like gene in this region.