Antibiotic Sensitivity Pattern among
Serratia marcescens
Isolates from
Blood Specimens in Sanglah Hospital
Lidya Handayani, Ketut Sukardika, I Dewa Made Sukrama, Ida Bagus Putra Dwija, Ni Nyoman Sri Budayanti
Clinical Microbiology Department, Faculty of Medicine, Udayana University
Keywords:Serratia marcescens, bacteremia, antibiotic sensitivity
INTRODUCTION
Bacteremia have serious impacts, especially in the pediatric patients. In Sanglah
Hospital, most blood samples suitable for culture come from pediatric ward and Serratia
marcescenswas the second most bacteria isolated from blood specimens. The most common
bacteria isolated was stillPseudomonas sp.
Serratia marcescens is a gram negative bacilli classified in the family of
Enterobacteriaceae1. This bacteria normally resides human gastrointestinal tract, but they are
also found in the environment and can even survive on the human skin for extended period of
time2. Morever, soap and detergents have been reported as potential sources for Serratia
marcescens outbreak2. This bacteria is also found to contaminate infusion solution3. In
clinical setting, this bacteria was confirmed to be one of the causative agent of hospital
acquired pneumonia, corneal ulcer among contact lenses wearer, bone and joint infection,
bacteremia, and any other infections in patients treated in Intensive Care Unit3. This bacteria
is a opportunistic agent that can rapidly spread in the nosocomial setting2. About 50%
nosocomial infection are caused by aerobic gram negative bacilli, including Serratia
marcescens3.There are several outbreaks ofSerratia marcescens in Neonatal Intensive Care
Unit (NICU) all around the world in recent years that has caused potentially fatal sepsis,
meningitis, or pneumonitis in the very premature and low birth weight infants, with mortality
rates about 44%2. Based on Clinical and Laboratory Standards Institute (CLSI) 2011, the first
antibiotic of choices for infection caused by this bacteria are Ampicillin, followed by
Cefazolin, Gentamycin, Tobramycin, and then Amikacin in relative order of choice4.
MATERIAL AND METHODS
Blood specimens were first incubated into Bactec until positivity observed. The blood
MacConkey agar and incubated at 37°C. After 18-24 hours of incubation period, the growth
of Serratia marcescens was first suspected by its colony morphology. The colony of
suspected Serratia marcescens appears brick red in MacConkey agar plate after 37°C
incubation for about 24 hours and prolonged incubation at room temperature. After
characterization of the colony growth, Gram staining and further identification using
Microgen were done. On Gram staining, it was shown to be gram negative bacilli.
Identification was done using commercial kit (Microgen) to confirm the presence ofSerratia
marcescensin the colony.
On the same day of identification, colony of Serratia marcescens were then cultured
to the Mueller Hinton agar and some antibiotic discs were placed. This agar was then
reincubated for another 24 hours before antibiotic sensitivity pattern examined.
RESULTS
During six months period (January – June 2011) of this observational study, there
were 29 Serratia marcescens isolates identified. For the blood specimens, Serratia
marcescens was the second most common bacteria isolated. All those isolates showed
resistance to Ampicillin/Sulbactam, Amoxicillin/Clavulanic acid, Cephalothin, Cefuroxime,
Ceftazidime, Aztreonam, and Gentamicin. Sensitivity to Chloramphenicol, Ciprofloxacin,
Trimethoprim/Sulfamethoxazole, Amikacin, Meropenem, and Imipenem were shown in
89,7%, 96,3%, 96,6%, 77,3%, 81,2%, and 65,2% isolates, respectively. There was also found
panresistant isolate. Furthermore, Serratia marcescens was not isolated from any other
specimens type.
DISCUSSION
This observational study clearly show that Serratia marcescens still become a
problem in the clinical setting in Sanglah Hospital. Antibiotic sensitivity pattern among
Serratia marcescens isolated from blood specimens in Sanglah hospital show all isolates
resistant to nearly all β-lactam antibiotics and some degree of sensitivity persists to any other
group of antibiotics. However, problems in the management of bacteremia caused by this
bacteria persist since antibiotic choices is quite restricted, especially for Pediatric patients.
Continuing reports in hospitals all around the world regardingSerratia marcescensoutbreaks
should alert all of us about the significance of this bacteria and the importance of preventing
any infection by any measures such as proper hand washing, proper antiseptic use before
REFFERENCES
1. Mahon, C.R., Lehman, D.C., Manuselis, G. (2011), Textbook of Diagnostic
Microbiology, 5thed, Saunders Elsevier, Missouri
2. Pollili, L., Parutti, G., et al, (2011), “Rapidly Control Outbreak of Serratia marcescens
Infection/Colonisations in a Neonatal Intensive Care Unit, Pescara General Hospital,
Pescara, Italy, April 2011”, Rapid Communications, available at:www.surveillance.org
3. Cohen, J., Powderly, W., et al, (2003), Infectious Diseases, 2nded, Mosby, Spain
4. Cockerill, F.R., Wikler, M.A., et al, (2011), Performance Standards for Antimicrobial
