Trafficking of methicillin-resistant staphylococci and co-colonization with vancomycin-resistant enterococci

To determine the trafficking of methicillin-resistant staphylococci between the hospital and community as well as the occurrence of co-colonization with vancomycin-resistant enterococci [VRE]. From November 2005 to April 2006, methicillin-resistant Staphylococcus aureus [MRSA] and methicillin-resistant coagulase-negative Staphylococcus [MRCoNS]-positive patients at the Salmaniya Medical Complex, Bahrain were assessed for VRE co-colonization. Characterization of vancomycin resistance genotype by PCR was carried out. Close family contacts were screened for MRSA and pulsed-field gel electrophoresis [PFGE] analysis of MRSA isolates from patient-family member pairs was conducted. One hundred and eighty-two patients [93 MRSA; 89 MRCoNS] and 356 family members were enrolled. Seven MRSA and 41 MRCoNS strains were isolated from the family members. PFGE analysis revealed the presence of variants of a single MRSA clone among patients and their relatives. A total of 112 patients [62 MRSA; 50 MRCoNS] provided stool for VRE screening. Of these 13 stool specimens [11.6%] were VRE-positive. All the VRE isolates were from MRSA-positive patients, thus positivity rate among MRSA patients was 20.9% [n/N = 13/62]. These were predominantly Enterococcus gallinarum with vanC1 genotype and one strain was Enterococcus faecium [vanB genotype]. Two E. gallinarum isolates harbored an additional vanB gene. The majority of VRE isolates were from patients in medical and surgical units [n/N = 10/13; 77%]. Male gender, prolonged hospitalization and presence of co-morbidities were significantly associated with MRSA/VRE co-colonization [p < 0.05]. MRSA/VRE co-colonization with MRSA trafficking between the hospital and community environment is a public health concern occurring in our setting

Frequency of virulence-associated genes in Enterococccus faecalis isolated in Kuwait hospitals

The objective of this study was to investigate the carriage of 6 virulence-associated genes in Enterococcus faecalis isolates obtained from patients in 8 hospitals in Kuwait. In total, 466 E. faecalis isolates were obtained from 313 urine samples, 68 wound swabs, 36 blood samples, 25 rectal swabs, 12 high vaginal swabs and 12 miscellaneous sources. Genes for gelatinase[gelE],aggregation substance [aggA], hemolysin activation factor [cylA], enhanced expression of pheromone [eep], enterococcal surface protein [esp], and E. faecalis endocarditis antigen A [efaA] were detected in PCR assays. Of 466 isolates, 423 [90.8%] were positive for 1 and up to 5 genes. However, none of the genes was detected in all of the isolates. The prevalence of the individual genes was eep: 31.9%; esp: 31.5%; gelE: 28.5%; efaA: 27.9%; aggA: 23.4%, and cylA: 18.5%. Of the 423 positive isolates, 148 [34.9%] were positive for 2 genes and 52 [12.3%], 15 [3.5%] and 5 [0.9%] isolates were positive for 3, 4 and 5 virulence genes, respectively. The efaA and esp combination was detected in isolates from all clinical sources. The study showed a high prevalence of virulence genes in E. faecalis isolated in Kuwait hospitals. The absence of a dominant gene in all of the isolates suggests that infections by E. faecalis may require the involvement of multiple virulence factors

Antimicrobial resistance in clinical isolates of Streptococcus pneumoniae in a tertiary hospital in Kuwait, 1997-2007: Implications for empiric therapy

This study evaluated antibiotic resistance trends in Streptococcus pneumoniae isolated in a tertiary hospital in Kuwait and its implications for empiric therapy. Antimicrobial susceptibility of 1353 strains of S. pneumoniae isolated from clinical specimens during 1997-2007 was performed by disc diffusion method. MIC was determined by E test. The results were compared for 1997-2001, 2002-2005 and 2006-2007. The prevalence of resistance for the respective periods were as follows: penicillin, 51.3%, 61.3% and 54.5%; erythromycin, 31.2%, 36.7% and 37.7%; tetracycline, 30.8%, 45.3% and 41.3%; co-trimoxazole, 49.5%, 58.5% and 62.8%; clindamycin, 20.4%, 20.6% and 24.5% and chloramphenicol, 8.1%, 8.9% and 3.7%. All were susceptible to vancomycin and rifampicin. For oxacillin-resistant isolates, penicillin resistance was rare [0.8%] with the new non-meningeal breakpoint. However, using the meningeal breakpoints, resistance increased for penicillin from 0.6%, to 28.7%, for cefotaxime from none to 16.5%, and for ceftriaxone from none to 7%. Intermediate resistance to meropenem increased from 1.7% to 22.4%. Multiple drug resistance increased from 22.4% to 37.8%. The study demonstrated that antimicrobial resistance of S. pneumoniae is increasing in Kuwait. However, the results of MIC determinations indicated that penicillin can still be used for therapy of non-meningeal infections. High prevalence of erythromycin resistance suggests that therapy of pneumonia with a macrolide alone may result in failure and should be based on results of susceptibility testing

Neonatal septicemia in Al - Jahra hospital, Kuwait: Etiologic agents and antibiotic sensitivity pattems

Neonatal septicemia [NNS] occurs frequently in neonatal intensive care units [NICU] and is often associated with high morbidity and mortality. However, information on its incidence and causative agents in Kuwait hospitals is scanty. To investigate the bacterial causative agents of NNS in a NICU and their susceptibility patterns to antimicrobial agents. Between May 1 and December 31, 1996, blood cultures were performed on all admissions to the Neonatal Unit, Al-Jahra Hospital, Kuwait, with the Bactec 9240 instrument [Becton Dickinson, USA]. Microorganisms were identified by cultural characteristics, Gram stain and biochemical profiles and antimicrobial susceptibility patterns performed by disk diffusion and by measuring their minimum inhibitory concentrations. From a total of 995 neonates admitted to the neonatal unit during the study period, 117 [11.7%] had positive blood cultures. Eighty-seven [8.7%] of the neonates had confirmed septicemia. Gram-positive organisms were cultured from 65 [75%] and gram-negative organisms from 22 [25%] of them. The most frequent organisms isolated were Staphylococcus epidermidis [34%], Streptococcus viridans [28%] and Candida species [14%]. Resistance to ampicillin and cephalosporins was detected in both gram-positive and gram-negative organisms associated with sepsis. Conclusions: The study identified the common bacterial pathogens associated with NNS in a neonatal unit, their susceptibility patterns to antimicrobial agents and emphasized the importance of understanding local epidemiology of NNS in formulating an antibiotic policy

Molecular diagnosis of antimicrobial resistance

Advances in molecular technology have helped in better understanding of mechanisms and diagnosis of diseases in many medical fields.Several molecular techniques are available for determining the genotypic drug-resistance and monitoring epidemic spread of a particular antimicrobial resistance gene in a hospital or patient population.The molecular [genotypic] testing has several advantages over conventional [phenotypic] testing in being faster and unambiguous, more accurate, able to detect masked resistance and can serve as a "gold" or "reference" test for detecting antibiotic resistance genes. This article addresses these molecular tests with their application and limitations and provide examples of their use especially in Mycobacterium tuberculosis and methicillin resistant Staphylococcus aureus