Nosocomial infections in NICU are one of the most important causes of morbidity and mortality [8, 9]. The mortality rates in NICU of resource constrained countries vary from 11.9 to 14.7%, much higher than the rates in high resource countries (6.1–7.1%) [15,16,17]. Microbial agents constantly inhabit the hospital environment including NICU. Bacterial contamination of NICU is one of the major factors responsible for higher incidences of nosocomial infections.
High bacterial contamination of frequently touched objects/instruments in NICU was recorded. Overall bacterial contamination rate in NICU was 74.6% (109/146) which is higher than other studies [18, 19]. Similar studies have reported contamination rates ranging from 59.2 to 67.8% [10, 19]. Higher bacterial contamination in NICU may be attributed to admission of neonates with variety of clinical conditions, overcrowded units, faecal contamination, easy access to visitors, understaffing and poor compliance to infection control practices. Prolonged NICU stay necessitates frequent visits by mothers and HCW result into increased human activities facilitating exchange of bacterial flora. Bacterial culture yielded wide variety of organisms ranging from opportunistic to potential pathogens. Common potential pathogens isolated were E. coli, Klebsiella species and S. aureus.
Different members of family Enterobacteriaceae colonize NICU and cause neonatal infections . The pathogens most often implicated in neonatal infections in resource constrained countries are Klebsiella species, E. coli, Pseudomonas and S. aureus . In our study findings, potential pathogens isolated from various surfaces were E. coli, Klebsiella species and S. aureus. Majority of the E. coli and Klebsiella species were recovered from incubators and suction tips. E. coli is frequently associated with neonatal sepsis and one of the most common causes of acute pyogenic meningitis among neonates. Surface contamination of NICU by E. coli and Klebsiella species lead to greater risk of systemic infections like neonatal septicemia, pneumonia and meningitis especially among the premature neonates. Contamination of NICU surfaces by Gram-negative bacilli is possibly associated with the faeces of the neonates. Among E. coli and Klebsiella isolates, 70.3% (19/27) and 71.4% (15/21) were ESBL producers respectively. High percentage of ESBL producing organisms limit the treatment choice and may result into treatment failure.
Another notorious nosocomial pathogen isolated was S. aureus. Surfaces of radiant warmers yielded highest number of S. aureus and MRSA. Hands of HCW and visitors are the common source of S. aureus and MRSA in hospital. Previous studies have documented that hands of HCW account for 20 to 40% infections due to cross-transmission within the units [22, 23]. Isolation of S. aureus from the surfaces of radiant warmers, stethoscopes and door handles indicate human hands as important source of S. aureus in NICU. Presence of S. aureus and MRSA on these surfaces increases the risk of transmission and may subsequently result into sepsis and pneumonia. Among S. aureus isolates, 33.3% were MRSA. Neonatal infections with MRSA are difficult to treat, leading to prolonged hospital stay and long term therapy. S. aureus has been identified as an important nosocomial pathogen due to its ability to survive on inanimate objects for several days . Biofilm formation helps long term survival of S. aureus. Majority of MRSA isolates 66.6% (4/6) in our study were biofilm producers. Previous study from Manipal hospital had reported slightly lower percentage (62.5%) of biofilm among MRSA isolates from environmental surfaces . This finding is alarming as MRSA isolates embedded in biofilm can survive longer and are potential source of nosocomial infections. There are limited data available in this field which studied biofilm production among environmental isolates.
Microbial flora of NICU surfaces is not significantly different from other units of the hospital environments. However, the additional challenge in preventing nosocomial infections in NICU is the high susceptibility of premature and immunocompromised neonates. Colonization of NICU surfaces by opportunistic nosocomial pathogens like Acinetobacter species, Coagulase negative Staphylococci, Pseudomonas species and Enterococcus species are important for the high risk neonates such as low birth weight, premature and congenital abnormalities. In this study, we observed high resistance of the bacterial isolates to commonly used antibiotics such as ampicillin, ceftazidime, ceftriaxone and ciprofloxacin. Similar findings have been reported in other studies [10, 25]. High percentage of MDR was observed among both Gram-negative and Gram-positive bacterial isolates. Among Gram-negative bacilli, more than 50% of the isolates were MDR which is alarming. Similarly, 27.7% (5/18) of S. aureus isolates were MDR. High percentage of MDR among bacterial pathogens could be attributed to use of higher generation of antibiotics for empirical treatment and use of prophylactic antibiotics for high risk mothers and neonates. Data of antibiotic resistance patterns of bacterial pathogens would help clinicians to formulate empirical antimicrobial therapy in suspected cases of nosocomial infections in NICU. This may help in reducing duration of NICU stay and neonatal mortality. The long term effect will be promoting antimicrobial stewardship.
Blood culture is one the most common microbiological investigations ordered from NICU. Blood culture data of NICU patients revealed that, S. aureus and Klebsiella species were two most common causes of neonatal sepsis. Similarities in antibiograms were observed among majority of S. aureus and Klebsiella species isolated from blood culture and in this study of NICU environment. This possibly indicates the nosocomial transmission of these pathogens resulting into sepsis. Comparing antibiotic resistance patterns of environmental isolates and blood culture isolates of NICU is one of the easy phenotypic method. This has been achieved in this study but not by other workers.
Many of the hospitals in resource constrained countries like Nepal, either have no NICU or have single NICU. Because of high bed occupancy in NICU, standard guidelines for cleaning/disinfection are poorly implemented. This results into increased bacterial colonization and subsequent spread within NICU. It is practically difficult to maintain sterility in the NICU environment because of high rate of HCW activities and use of equipments. Meticulous cleaning/disinfection protocols are necessary to prevent the retention and spread of virulent microbial pathogens in sensitive environment of NICU. In this study we have included most of the objects/instruments commonly touched by HCWs and objects which frequently come in contact of neonates. This is an attempt to determine relevance of flora on these objects and their role in nosocomial infections. The findings of this study have provided baseline information about the degree of contamination and resistance patterns of environmental isolates.
Findings of this study are important to generate awareness among healthcare professionals of resource constrained countries regarding contamination of NICU and their possible role in neonatal nosocomial infections. This study will stimulate scientists/researchers of resource constrained countries to explore more about neonatal nosocomial infections and devise possible preventive measures.
Limitations of the study
Association of potential pathogens isolated from objects/instruments of NICU in sepsis was demonstrated only based on antibiogram of the isolates. Genotypic characterization of the isolates was not performed. Biofilm property was studied only for S. aureus isolates. This was single center, time limited study conducted in one tertiary care hospital and results may not be generalized.