Low prevalence of methicillin resistant as determined by an automated identification system in two private hospitals in Nairobi, Kenya: a cross sectional study

Background: Staphylococcus aureus (S.aureus) is a major cause of both healthcare and community acquired infections. In developing countries, manual phenotypic tests are the mainstay for the identification of staphylococci with the tube and slide coagulase tests being relied upon as confirmatory tests for S. aureus. The subjectivity associated with interpretation of these tests may result in misidentification of coagulase negative staphylococci as S.aureus. Given that antibiotic resistance is more prevalent in CONS, this may result in over estimation of methicillin resistant S.aureus (MRSA) prevalence. Methods: A review of susceptibility data from all non-duplicate S.aureus isolates generated between March 2011 and May 2013 by the Vitek-2 (bioMérieux) automated system was performed by the authors. The data was generated routinely from processed clinical specimens submitted to the microbiology laboratories for culture and sensitivity at the Aga Khan University Hospital and Gertrude’s children’s hospital both situated in Nairobi. Results: Antimicrobial susceptibility data from a total of 731 non-duplicate S.aureus isolates was reviewed. Majority (79.2%) of the isolates were from pus swabs. Only 24 isolates were both cefoxitin and oxacillin resistant while 3 were resistant to oxacillin but susceptible to cefoxitin giving an overall MRSA prevalence of 3.7% (27/731). None of the isolates were resistant to mupirocin, linezolid, tigecycline, teicoplanin or vancomycin. Conclusion: The prevalence of MRSA in this study is much lower than what has been reported in most African countries. The significant change in antibiotic susceptibility compared to what has previously been reported in our hospital is most likely a consequence of the transition to an automated platform rather than a trend towards lower resistance rates

A ten-year review of neonatal bloodstream infections in a tertiary private hospital in Kenya

Introduction: Neonatal mortality in developing countries is usually due to an infectious cause. The gold standard of investigation in developing countries is a positive blood culture. It is important to know the aetiology of neonatal bloodstream infections so that empiric treatment can be effective. Methodology: We conducted a retrospective clinical audit over ten years between January 2000 until December 2009, looking at the aetiology of both early and late onset neonatal sepsis. We analysed data from 152 (23%) patient isolates out of 662 suspected cases of neonatal sepsis. Results: Our study revealed that Gram-positive organisms were the predominant cause of both early and late onset sepsis; the common isolates were Staphylococcus epidermidis (34%) and Staphylococcus aureus (27%). There were no isolates of group B Streptococcus. Candida species was isolated only in patients with late onset sepsis (6.9%). Bacterial isolates were relatively sensitive to the commonly used first- and second-line empiric antibiotics. Conclusion: Gram-positive organisms remain the major cause of neonatal bloodstream infections in our setup. The findings of this study will guide clinicians in prescribing the right empiric therapy in cases of suspected neonatal sepsis before the definitive culture results are obtained

Molecular characterization of multidrug-resistant Klebsiella pneumoniaeand Escherichia coliharbouring extended spectrum beta-lactamases andcarbapenemases genes at a tertiary hospital, Kenya

Background: Multidrug-resistant (MDR) Gram negative rods are increasingly being reported in sub-Saharan Africa. Molecular investigations play an important role, alongside other measures, in controlling nosocomial infections attributed to these organisms. This study aimed to determine the common extended spectrum beta-lactamases (ESBL) and carbapenemases genes, and clonal relationship in MDR Klebsiella pneumoniae and Escherichia coli. Methods: Fifty-four MDR isolates collected at the Aga Khan University hospital, Nairobi in the month of August 2012 formed the study. These were picked after an increase in the number of resistant strains during the said period was experienced. Results: blaCTXM was present in 41 (74%) of the isolates, while blaSHV was detected in 18 (33%) and blaTEM in 13 (24%) of the isolates. Nine (16.7%) of the isolates harboured all three ESBL genes and 8 (14.8%) harboured two. Eight of the isolates (all E. coli) had none of the ESBL genes tested. Two isolates harboured carbapenemases genotypes: one had blaNDM-1 and the other blaSPM. Sequencing matched CTXM-15 and TEM-1 genes in all the isolates harbouring blaCTXM and blaTEM respectively. However, there was diversity in blaSHV with SHV-11 and SHV-12 genes predominant. The isolates were non-clonal. Conclusions: The isolates mostly harboured blaCTX-M-15 while only a few had carbapenemases genes. Lack of clonality suggests these were the stable circulating strains at the time of the study

Validation of c-reactive protein in the early diagnosis of neonatal sepsis in a tertiary care hospital in Kenya.

Objective: To evaluate utility of C-reactive protein (CRP) in the early diagnosis of neonatal sepsis in a tertiary care Newborn Unit in Kenya. Design: Cross-sectional study. Setting: Newborn Unit, Kenyatta National Hospital. Subjects: All neonates admitted to Newborn Unit, Kenyatta National Hospital during the study period with suspected sepsis based on specified clinical criteria. Results: Of the 310 infants, there were 83 episodes of proven sepsis and 94 episodes of probable sepsis. Using the standard CRP cut-off value of 5 mg/dl, a sensitivity of 95.2% in proven sepsis and 98.9% for probable septic episodes were noted. In proven sepsis, a specificity of 85.3%, positive predictive value of 80.6%, and a negative predictive value of 96.5% were noted. In probable sepsis, a specificity of 83.3%, positive predictive value of 80.9% and a negative predictive value of 99.1% were noted. The overall accuracy in proven sepsis was 96.5%, and in probable sepsis was noted to be 99.1%. Sub-analysis showed a lower positive predictive value (61.5%) for early onset sepsis compared to 93% for late onset sepsis. Repeat CRP tests were done in 33 babies. Twenty two of the 29 with proven/probable infection had a ten-fold increase in CRP levels, but levels were noted to be low or reducing in seven (24.1%) babies showing signs of improvement clinically. Using a receiver operator characteristic curve, the optimal cut-off point for CRP was found to be 5 mg/dl. Conclusions: Serum CRP is an accurate indicator of neonatal sepsis, with high sensitivity, specificity and predictive values, at the standard cut-off of 5. CRP is a better screening test for late-onset than early-onset neonatal sepsis. The standard recommended CRP cut -off point of 5 is appropriate for local use

Antimicrobial resistance patterns in extended-spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae isolates in a private tertiary hospital, Kenya

Background: Extended-Spectrum β-Lactamase (ESBL) producing Enterobacteriaceae have become widespread in hospitals and are increasing in community settings where they cause a variety of infections. In addition to hydrolyzing most beta-lactam agents, bacteria harboring these enzymes display resistance to other unrelated antimicrobial agents and thus often pose a therapeutic dilemma. Though these resistance patterns have been studied elsewhere within Africa, such data from hospitals in Kenya are scanty. We therefore undertook to determine these patterns at the Aga Khan University hospital by studying multidrug resistant Escherichia coli and Klebsiella pneumoniae isolates from patients\u27 samples. Findings: A total of 159 isolates (109 E. coli and 50 K. pneumoniae) were confirmed as ESBL producers and tested against eighteen antimicrobials. The proportion of resistant isolates was high (\u3e80%) for the antimicrobials tested with the exception of the carbapenems (\u3c1%), nitrofurantoin (23%) and gentamicin (63%). Klebsiella pneumoniae had a higher proportion of isolates resistant to ceftazidime, gentamicin and nitrofurantoin (P \u3c 0.05) than E. coli which had a higher proportion of isolates resistant to ciprofloxacin, levofloxacin and tetracycline (P \u3c 0.05). Conclusions: In our study, antimicrobial coresistance is common in ESBL producers; however resistance to carbapenems is low and these drugs would be the appropriate empiric therapy for serious or life threatening systemic infections. Nitrofurantoin retains good activity among the multidrug resistant isolates and can be the drug of choice for non-complicated urinary tract infections due to ESBL producing E. coli

Comparison of Clinical Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing guidelines for the interpretation of antibiotic susceptibility at a University teaching hospital in Nairobi, Kenya: a cross-sectional study

Background: The Clinical Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines are the most popular breakpoint guidelines used in antimicrobial susceptibility testing worldwide. The EUCAST guidelines are freely available to users while CLSI is available for non-members as a package of three documents for US $500 annually. This is prohibitive for clinical microbiology laboratories in resource poor settings. We set out to compare antibiotic susceptibility determined by the two guidelines to determine whether adoption of EUCAST guidelines would significantly affect our susceptibility patterns. Methods: We reviewed minimum inhibitory concentrations (MIC) of various antibiotics routinely reported for Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) isolates from an automated microbiology identification system (VITEK-2) at the Aga Khan University Hospital Nairobi’s Pathology department. These MICs were then analyzed using both CLSI 2015 and EUCAST 2015 guidelines and classified as resistant, intermediate or susceptible. We compared the susceptibility and agreement between the CLSI and EUCAST categorizations. Results: Susceptibility data from a total of 5165 E. coli, 1103 S. aureus and 532 P. aeruginosa isolates were included. The concordance rates of the two guidelines for E. coli, S. aureus and P. aeruginosa ranged from 78.2 to 100 %, 94.6 to 100 % and 89.1 to 95.5 % respectively. The kappa statistics for E. coli MICs revealed perfect agreement between CLSI and EUCAST for cefotaxime, ceftriaxone and trimethoprim–sulfamethoxazole, almost perfect agreement for ampicillin, ciprofloxacin, cefuroxime, gentamicin and ceftazidime, substantial agreement for meropenem, moderate agreement for cefepime and amoxicillin-clavulanate, fair agreement for nitrofurantoin and poor agreement for amikacin. For S. aureus the kappa statistics revealed perfect agreement for penicillin, trimethoprim–sulfamethoxazole, levofloxacin, oxacillin, linezolid and vancomycin, almost perfect agreement for clindamycin, erythromycin and tetracycline and moderate agreement for gentamicin. For P. aeruginosa the kappa analysis revealed moderate to almost perfect agreement for all the anti-pseudomonal antibiotics. Conclusion: The results show comparable antibiotic susceptibility patterns between CLSI and EUCAST breakpoints. Given that EUCAST guidelines are freely available, it makes it easier for laboratories in resource poor settings to have an updated and readily available reference for interpreting antibiotic susceptibilities

Spectrum of Microbial Diseases and Resistance Patterns at a Private Teaching Hospital in Kenya: Implications for Clinical Practice

Background: Accurate local prevalence of microbial diseases and microbial resistance data are vital for optimal treatment of patients. However, there are few reports of these data from developing countries, especially from sub-Saharan Africa. The status of Aga Khan University Hospital Nairobi as an internationally accredited hospital and a laboratory with an electronic medical record system has made it possible to analyze local prevalence and antimicrobial susceptibility data and compare it with other published data. Methods: We have analyzed the spectrum of microbial agents and resistance patterns seen at a 300 bed tertiary private teaching hospital in Kenya using microbial identity and susceptibility data captured in hospital and laboratory electronic records between 2010 and 2014. Results: For blood isolates, we used culture collection within the first three days of hospitalization as a surrogate for community onset, and within that group, Escherichia coli was the most common, followed by Staphylococcus aureus. In contrast, Candida spp. and Klebsiella pneumoniae were the most common hospital onset causes of bloodstream infection. Antimicrobial resistance rates for the most commonly isolated Gram negative organisms was higher than many recent reports from Europe and North America. In contrast, Gram positive resistance rates were quite low, with 94% of S. aureus being susceptible to oxacillin and only rare isolates of vancomycin-resistant enterococci. Conclusions: The current report demonstrates high rates of antimicrobial resistance in Gram negative organisms, even in outpatients with urinary tract infections. On the other hand, rates of resistance in Gram positive organisms, notably S. aureus, are remarkably low. A better understanding of the reasons for these trends may contribute to ongoing efforts to combat antimicrobial resistance globally

Resistance patterns of Mycobacterium tuberculosis isolates from pulmonary tuberculosis patients in Nairobi

Introduction: In Kenya, which ranks thirteenth of 27 high tuberculosis burden countries, diagnosis is based on Ziehl-Neelsen staining alone and patients are treated without information on sensitivity patterns. This study aimed to determine resistance patterns of Mycobacterium tuberculosis isolated from pulmonary samples. Methodology: Pulmonary tuberculosis patients in Nairobi were randomly sampled after informed consent and recruited into the study using a structured questionnaire. Specimens were cultured in liquid and solid media, and drug susceptibility tests were performed for first-line drugs including (isoniazid, rifampin, streptomycin, ethambutol and pyrazinamide). Results: Eighty-six (30%) of 286 isolates were resistant to at least one of five antibiotics tested. Thirty-seven (30.2%) isolates were resistant to isoniazid; 15 (11.6%) to streptomycin; 13 (4.5%) to ethambutol; four (1.4%) to rifampin ; and 30 (10.4%) to pyrazinamide. Double resistance was seen as follows: four (1.4%) isolates were resistant to both isoniazid and pyrazinamide; four (1.4%) to streptomycin and isoniazid; and one (0.3%) to rifampin and streptomycin. Two isolates (0.7%) were multidrug resistant, and one was triple resistant with an additional resistance to ethambutol. Results also showed 88.7% of patients were below the age of 40 years, while 26.3% were HIV positive. The majority of the patients (66.5%) were unemployed or self-employed in small businesses, with 79.4% earning less than 100 USD per month. Conclusion: The high resistance observed in isoniazid, which is a first-line drug, could result in an increase in multidrug resistance unless control programs are strengthened. Poverty should be addressed to reduce infection rates

Comparison of biomarker based Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) and conventional methods in the identification of clinically relevant bacteria and yeast

Background: MALDI-TOF MS is an analytical method that has recently become integral in the identification of microorganisms in clinical laboratories. It relies on databases that majorly employ pattern recognition or fingerprinting. Biomarker based databases have also been developed and there is optimism that these may be superior to pattern recognition based databases. This study compared the performance of ribosomal biomarker based MALDI-TOF MS and conventional methods in the identification of selected bacteria and yeast. Methods: The study was a cross sectional study identifying clinically relevant bacteria and yeast isolated from varied clinical specimens submitted to a clinical laboratory. The identification of bacteria using conventional Vitek 2™ automated system, serotyping and MALDI-TOF MS was performed as per standard operating procedures. Comparison of sensitivities were then carried out using Pearson Chi-Square test and p-value of Results: Of the 383 isolates MALDI-TOF MS and conventional methods identified 97.6 and 95.7% (p = 0.231) to the genus level and 97.4 and 88.0% (p = 0.000) to the species level respectively. Biomarker based MALDI-TOF MS was significantly superior to Vitek 2™ in the identification of Gram negative bacteria and Gram positive bacteria to the species level. For the Gram positive bacteria, significant difference was observed in the identification of Coagulase negative Staphylococci (p = 0.000) and Enterococcus (p = 0.008). Significant difference was also observed between serotyping and MALDI-TOF MS (p = 0.005) and this was attributed to the lack of identification of Shigella species by MALDI-TOF MS. There was no significant difference observed in the identification of yeast however some species of Candida were unidentified by MALDI-TOF MS. Conclusion: Biomarker based MALDI-TOF MS had good performance in a clinical laboratory setting with high sensitivities in the identification of clinically relevant microorganisms