1.An eight-year review of blood culture and susceptibility among sepsis cases in an emergency department in North eastern Malaysia
Hashairi, F.* ; Hasan, H. ; Azlan, K. ; Deris, Z.Z.
Tropical Biomedicine 2011;28(3):599-605
An understanding of common pathogens and their antibiotic sensitivity patterns is
critical for proper management of sepsis in Emergency Department (ED). The goal of the
study was to identify common organisms isolated from blood cultures of patients attended to
ED and their antimicrobial susceptibility. Beginning from 2002, all cases of positive blood
culture collected by the ED, Hospital Universiti Sains Malaysia (HUSM) were recorded and
analysed. Over the period of eight years, we documented 995 cases of positive blood cultures.
Of these samples, 549 (55.2%) were Gram-negative bacteria; 419 (42.1%) were Gram-positive
bacteria; 10 (1.0%) were anaerobic organisms; 10 (1.0%) were fungus; and 7 (0.7%) cases
were mixed organisms. Gram-negative bacteria were observed to develop more resistance to
antimicrobial agents, especially those commonly used in an outpatient setting with less than
80% sensitivity to ampicillin, cotrimoxazole and ciprofloxacin. By contrast, there has been no
marked change in the sensitivity trends of Gram-positive bacteria over the same period. In
conclusion, ED physicians are more equipped to initiate empirical antimicrobial therapy
especially when dealing with possibility of Gram-negative sepsis.
2.Reduced susceptibility of Burkholderia pseudomallei following exposure to carbapenem
Zamani, A. ; Zueter, A.R. ; Muhd Besari, A. ; Hasan, H. ; Harun, A. ; Deris, Z.Z.
Tropical Biomedicine 2020;37(No.3):783-790
Reduced susceptibility in Burkholderia pseudomallei during carbapenem therapy may lead to treatment failure. We isolated a clinical strain that had developed reduced susceptibility to carbapenems while on treatment. After reviewing the patient’s clinical notes, the initial isolate (BUPS01/14) was exposed to carbapenem in vitro to mimic the clinical scenario. The stability of susceptibility of the carbapenem-exposed strain (BUPS01/14R) was examined by serial subculture in antibiotic-free broth. Biochemical and morphological comparison was performed by the VITEK® system and electron microscopy. MICs increased 32-fold following carbapenem exposure and became stable in the antibiotic-free environment. On electron microscopic examination, the BUPS01/14R cells were smoother and less wrinkled compared to BUPS01/14 cells. This report highlights a potential anti-melioidosis treatment failure due to the emergence of resistance while on carbapenem monotherapy. Further study of this strain is necessary to understand the mechanism of resistance at a molecular level.
3.In-vitro activity of β-lactams/trimethoprim-sulfamethoxazole combinations against different strains of Burkholderia pseudomallei
Mohamad, N.I. ; Harun, A. ; Hasan, H. ; Deris, Z.Z.
Tropical Biomedicine 2022;39(No.1):11-16
Trimethoprim-sulfamethoxazole is an active agent against Burkholderia pseudomallei and is
being used in intensive and maintenance phases of melioidosis therapy. In this study, we
evaluated the bactericidal activities of β-lactams (imipenem, ceftazidime and amoxicillinclavulanate) alone and in combinations with trimethoprim-sulfamethoxazole against
B. pseudomallei. Four clinical strains of B. pseudomallei were selected based on different
genotypes that are frequently found in Malaysia. The minimum inhibitory concentrations of
trimethoprim-sulfamethoxazole, ceftazidime, imipenem and amoxicillin-clavulanate were
determined using microdilution broth method. The bactericidal activities and synergy effects
of β-lactams and/or trimethoprim-sulfamethoxazole were evaluated by checkerboard and
static time-kill analyses at 1×MIC concentration of each antibiotic. Using checkerboard
method, the β-lactam/trimethoprim-sulfamethoxazole combinations exhibited ΣFIC of
0.75-4.00. In time-kill analysis, ceftazidime/trimethoprim-sulfamethoxazole combination
demonstrated synergy against three strains (less 2.25-2.41 log10CFU/mL compared to the
most active antibiotic monotherapy) whereas imipenem/trimethoprim-sulfamethoxazole
combination regimen showed synergy against one strain (less 3.32 log10CFU/mL). No
antagonist effect or major re-growth was observed in all combination regimens, whereas 11
out of 12 of β-lactam monotherapy regimens were associated with re-growth of bacteria.
However, all β-lactam monotherapy regimens exhibited rapid and stronger killing activities
against BUPS/07/14, in the initial 12 hours compared to β-lactam/ trimethoprimsulfamethoxazole combination regimens. The combination of β-lactams with trimethoprimsulfamethoxazole demonstrated better killing effect at 24 hours compared to monotherapy
and no major bacterial regrowth was observed. Nevertheless, delay in killing activities of
β-lactam/trimethoprim-sulfamethoxazole combination regimens against BUPS/07/14 need
further examination because this phenomenon can lead to treatment failure in some
patients.