Our findings show that there are many bacterial pathogens carried and harbored by cockroaches residing in the intensive neonatal care unit of Tikur Anbessa Hospital. These pathogens are common causes of neonatal nosocomial sepsis. Most isolated strains were multi-drug resistant. These findings indicate that cockroaches might be potential vectors for multidrug resistant bacteria pathogens in a neonatal intensive care unit set up and that their effective control and extermination is an important addition to infection prevention.
The "batching" of cockroaches used in this study might have hampered the identification of bacterial load of each cockroach in the batch. However, since the main purpose of the study was to identify the possible effect of cockroaches in NICU microbiology, the findings are important indicators of the need for urgent control of these potential vectors.
All cockroaches in this study were identified as Blatella germanica
, a species widely associated with humans. This was also demonstrated by another study in Addis Ababa [6
]. Two Klebsiella
species were found to be the most frequent isolates in the current study. Klebsiella
was also isolated from cockroaches by other researchers elsewhere in ICU and non-ICU settings [11
]. This pathogen is the most common cause of neonatal sepsis in the same neonatal intensive care unit where we conducted our study [29
]. The Klebsiella
species isolated in our study were multidrug resistant; this was similarly documented by a study in TAH-NICU which demonstrated isolation of multidrug resistant Klebsiella
from blood cultures of sick newborns.
] However, the level of resistance of this pathogen for most antimicrobials was higher than most control studies [11
was reported as important cause of neonatal nosocomial infections accounting for more than a third of all the identified infections in a study in Nepal [32
]. The fact that cockroaches carry Citrobacter
spp. has been shown by researchers elsewhere, though isolation was reported to be from house roaches [11
]. In another study, the sources of nosocomial Citrobacter
infection were indicated to be the hands of medical staff, water for injection, face masks, nasal prongs, stethoscopes, etc. [32
]. However, the current study showed that Citrobacter
species was the second most common isolate from cockroaches residing in the NICU. This finding is important as it points to one of the significant vectors for transmission of this emerging neonatal pathogen. The fact that the isolates showed a multi-drug resistant pattern is in agreement with a study by Khadka et al.
]. In that study, the sensitivity of Citrobacter
species to floroquinolones was shown to be higher, which is in agreement with our findings of good sensitivity for Norfloxacin and Ciprofloxacin.
nosocomial infection is one of the devastating gram-negative neonatal infections. There are numerous studies which isolated Pseudomonas
spp. from cockroaches in hospital settings [11
spp. is one of the common blood culture isolates from sick newborns in the TAH-NICU [33
]. Hence, our findings strengthen the evidence that cockroaches may play a vector role for transmission of organisms to newborns. There was a multi-drug resistance pattern among all the isolates of Pseudomonas
spp. Sensitivity for Floroquinolones (Ciprofloxacin and Norfloxacin) was found to be 95% as opposed to a 0%and 21% sensitivity to penicillin and gentamicin respectively. Similarly, resistance was reported to be 71.4%, 57.1% and 14.3% for Ampicillin, Gentamicin and Ciprofloxacin, respectively, by Hsiu-Hua Pai et al.
] couldn't find NICU isolates of Pseudomonas
from cockroaches, preventing comparison with our findings.
. neonatal bacteremia was found to be among the commonly encountered causes of neonatal sepsis by various bacteriologic studies [33
]. Cockroaches as carriers of Enterobacter
spp. were demonstrated by several studies elsewhere [11
]. We showed that the most common Enterobacter
species was Enterobacter cloacae
. Finnstrom et al. [37
] and Hervas et al. [38
] reported outbreaks of Enterobacter cloacae
sepsis in neonatal ICUs. Hence, isolation of a high load of Enterobacter cloacae
from cockroaches sharing a room with neonates in this study is an important finding indicating the possible sources of infection. The current study also demonstrated the multi-drug resistant pattern of Enterobacter spp;
a better sensitivity to floroquinolones (Ciprofloxacin and Norfloxacin) was observed, a pattern in agreement with the findings by Roy et al.
. was isolated from several health facilities in Ethiopia infested by cockroaches, including restraunts and hospitals [6
]. But it has not been reported from the NICU of Tikur Anbessa Hospital. There are a considerable number of studies on the distribution and drug susceptibility pattern of Salmonella
spp. in Ethiopia but there is no consistent finding on the predominant serotype. Salmonella
microbiologic studies by Mache [41
] and Asrat [31
] showed a predominance of Salmonella
serotype B, whereas a similar study by Beyene [42
] revealed a higher number of serotype C isolates. Tachbele et al.
] reported the most commonly isolated serotype from cockroaches as serotype B and didn't demonstrate isolation of serotype C. However, all the salmonella isolates in the current study were serotype C1. To resolve this discrepancy, a larger scale study may be required. There was a 100% sensitivity and resistance to Floroquinolones and Gentamicin, respectively. Resistance was also 100% for Penicillin and Chloramphenicol. A similar pattern was reported by control studies [43
The finding of more resistance to Gentamicin and Trimethoprim-sulfamethoxazole among gut isolates in the current study was not shown in other cockroach researches for comparison.
Other smaller isolates of pathogenic organisms which similarly grew in other studies [6
] included Providencia retegerri, Staphylococcus aureus, E. coli, Acinetobacter spp
. and Shigella flexneri. Non Group A. streptococcus
was isolated from both external and internal samples. This isolate was not described in other cockroach microbiologic studies elsewhere.
Based on the current and previous findings, the link between cockroaches and nosocomial infection has been established warranting provision of an effective and integrated pest management system. Such effective system of environmental control of cockroaches has to be implemented because of their notoriously resilient character and ability to readily infest diverse habitats [47